M2compiler-V3/compiler/src/M2.atg

COMPILER M2
(* Step 1 — minimal integer pipeline (m2compiler-V3).
   Subset: program MODULE + CONST (literal) + VAR INTEGER +
   assignment + integer expressions (+ - * DIV MOD, leading sign,
   parens). Fresh QBE backend (QbeGen) to gen_ssa/<Module>.ssa;
   assemble with qbe, link with cc.

   Test convention: a global VAR ExitCode : INTEGER makes generated
   $main return its value as the process exit code, else return 0.

   Semantic errors reuse the V1/V2/Test2 family: 200 duplicate,
   201 undeclared, 202 module name mismatch, 210 bad assignment,
   211 bad arithmetic, 221 not a type, 230 not supported yet,
   231 opaque type outside definition.
   Scalar-phase TYPEs (named, integer subrange, enum) check fully;
   composite forms wait for step 3.    Procedure headings (formals,
   result, FORWARD) enter scopes now; bodies parse + check with one
   230 at END (lowering = step 4).
   Statements: assignment, IF/ELSIF/ELSE, WHILE, REPEAT/UNTIL,
   LOOP/EXIT (230 outside LOOP), FOR/TO/static-sign-BY, full CASE
   (labels, ranges, ELSE; compare-chain), RETURN with 232 checks
   (outside proc / value mismatch / missing value). WITH waits for
   records (step 3). Boolean connectives are eager (or/and/xor);
   relations yield 0/1 via cXXw.
   Clarion-form classes (docs/OOP.txt): CLASS decl + single
   inheritance + CLASS IMPLEMENTATION blocks, methods with ";"
   (per the Table example, not the sketch's ","), VIRTUAL flagged.
   Scopes and member checks now; lowering later (one 230 per
   class/impl block). Classic identifiers: no underscores, so the
   Table example's _names stay lexically out of reach.
   Step 3.1 arrays: "ARRAY [lo..hi, ...] OF T" (folded literal
   bounds, int/char) and open "ARRAY OF T" formals; index suffixes
   with per-level checks (217/218, trap on breach via $abort);
   whole-array ":=" with runtime count check + blit; string
   literals lower as descriptors (1-char stays CHAR, empty works);
   array/string "=" is 213 (no built-in whole comparison).
   Step 3.3 sets: multi-word masks (no header, static words) over
   bases ≤ 256 values; literals are SET OF [0..255] (222 on
   out-of-span); + - * / as or/and/xor-not, IN with span trap,
   =/# word-wise (lenient cross-base); CASE labels reject sets.
   Step 3.4 records: flat blobs; array fields are pointers to static
   descriptors (locked amendment — one layout per type); nested
   records inline; static declaration-order offsets; field chains
   mix with indexes; WITH pushes fields + bases (215/216);
   whole-record deep copy; record/set/class "=" is 213.
   Step 3.6 pointers: vars (l), NIL as a real type (FNil — assignment
   and =/# work, everything else 210-214/222), ^ deref with sfx
   discipline (address flows, load at use; chains compose),
   pointer =/# via ceql/cnel (< > etc. are 213), NEW/DISPOSE as
   builtin statements via extern malloc/free (recursive skeleton
   init; DISPOSE shallow and nils, deviating from Wirth-undefined);
   nil-deref is raw (no check). *)

IMPORT SymTab, QbeGen, AST, Lower;

VAR
  (* Two-phase parse (docs/plan-two-phase-parse.md), milestone 1.  When
     TRUE each outermost procedure/method body is shadow-skipped at the
     token level and the skip verified before the body parses normally.
     Set by the driver (-notwophase turns it off); default on.
     Blocks being parsed so only outermost bodies probe. *)
  twoPhaseParse: BOOLEAN;

  (* Two-phase parse spans (milestone 2a): one entry per outermost body
     shadow-skipped while twoPhaseParse is on — procedure name and the
     buffer offset its body starts at (the lookahead token's nextPos).
     Per-parse; nothing consumes the table yet. *)
  nSpans: CARDINAL;
  spanName: ARRAY [0 .. 1023] OF SymTab.Name;
  spanStart: ARRAY [0 .. 1023] OF M2S.INT32;
  spanIdx: ARRAY [0 .. 1023] OF CARDINAL;
  spanTy: ARRAY [0 .. 1023] OF INTEGER;
  spanNode: ARRAY [0 .. 1023] OF AST.Node;

  (* Two-phase parse (milestone 2c): phase-1 skips a module-level proc
     body (DeferSkip) and phase 2 re-parses it at unit end (RepassAll).
     `deferredBody` reports the skip to ProcDecl's close choice;
     `repassing` disables deferral during phase 2; `allowDefer` limits
     deferral to plain ProcDecls (methods stay inline); `curProcNode` is
     the NkProcDecl whose body is about to be parsed. *)
  deferredBody: BOOLEAN;
  repassing: BOOLEAN;
  allowDefer: BOOLEAN;
  curProcNode: AST.Node;

  (* Result slot for the expression-AST builder (slice 2).  Every
     Expr/SimExpr/Term/Fact leaves its node here; the combination
     productions save it into locals before parsing the next operand.
     `astIsLit` in Fact is per-invocation, so a nested Fact cannot make
     an outer non-literal Fact look literal. *)
  astCur: AST.Node;

  (* Actual-argument nodes collected by ActParam for the call being
     parsed by ArgList (slice 4).  Fact resets the count before the
     optional ArgList and then folds the nodes into an NkCall. *)
  astNArgs: CARDINAL;
  astArgs: ARRAY [0 .. 31] OF AST.Node;

  (* Statement-AST result slot (slice 5): the most recently parsed
     statement.  StatSeq folds these into an NkBlock. *)
  astStmt: AST.Node;

  (* Declaration-AST result slot (slice 6): the most recently built
     declaration; DeclSeq folds these into an NkDeclSeq. *)
  astDecl: AST.Node;

  (* The local declarations of the most recent Block (a procedure body);
     ProcDecl stores them as the proc node's child 2. *)
  astBlkDecls: AST.Node;

  (* Unit-AST root (slice 7): NkUnit(name, decls, body). *)
  astUnit: AST.Node;

  (* Import accumulator (slice 11): `{ Import }` appends NkImport
     nodes here; each unit stores them as NkUnit child[3]. *)
  astImp, astImpTail: AST.Node;

  (* Class-AST accumulators (slice 13): the class node currently being
     parsed and its parent/field/method lists.  Classes are not nested
     inside one another, so module-level state is safe. *)
  astCls, astClsP, astClsPTail, astClsF, astClsFTail,
  astClsM, astClsMTail, astMethod: AST.Node;

  (* Class of the method named by the last `obj.Method` designator
     (InvalidType when the callee is an ordinary procedure). Set by
     Design, consumed by the following ArgList. *)
  methCls: SymTab.TypeIndex;
  (* Class of the type of the innermost `TypeName{...}` brace
     constructor (ClSet or ClArray); dispatches BraceElem. *)
  braceCls: INTEGER;
  (* Module-level VAR declarations whose type was still an unresolved
     forward alias at declaration time; emitted once the TYPE block
     completes (module scope only). *)
  nPendVar: CARDINAL;
  pendVarName: ARRAY [0 .. 255] OF SymTab.Name;
  pendVarT: ARRAY [0 .. 255] OF SymTab.TypeIndex;
  (* Forward module-level variables referenced from a procedure body. *)
  (* GOTO/labels: the label and goto names of the procedure being parsed,
     reset per procedure and checked at its END. *)
  nLab, nGot: CARDINAL;
  labNm, gotNm: ARRAY [0 .. 255] OF SymTab.Name;

  (* Generics (Increment 1): the last refining module seen — instance
     name, generic name, and the actual type parameters. *)
  refInst, refGen: SymTab.Name;
  refN: CARDINAL;
  refActual: ARRAY [0 .. 15] OF SymTab.TypeIndex;
  isGen: BOOLEAN;

  (* Generics (Increment 2): instantiation re-parse context.  When the
     driver re-parses a generic's source to instantiate it as `instName`,
     instActive is TRUE, the module is renamed, and each type formal is
     bound to the corresponding instActual entry. *)
  instActive: BOOLEAN;
  instName: SymTab.Name;
  instActual: ARRAY [0 .. 15] OF SymTab.TypeIndex;
  instN: CARDINAL;
  instFk: CARDINAL;   (* formal cursor while binding during re-parse *)

  (* Identity of the last-parsed unit and refinement, for the driver's
     generic registry and its re-parse decision. *)
  unitName: SymTab.Name;
  unitWasGen: BOOLEAN;
  unitWasDef: BOOLEAN;
  refSeen: BOOLEAN;
  refIsDef: BOOLEAN;


PROCEDURE CopyNm (src: ARRAY OF CHAR; VAR dst: SymTab.Name);
  VAR i: CARDINAL;
  BEGIN
    i := 0;
    WHILE (i <= HIGH(dst)) AND (i <= HIGH(src)) AND (src[i] # CHR(0)) DO
      dst[i] := src[i]; INC(i)
    END;
    IF i <= HIGH(dst) THEN dst[i] := CHR(0) END
  END CopyNm;

PROCEDURE InInst () : BOOLEAN;
  BEGIN RETURN instActive END InInst;

PROCEDURE InstNameGet (VAR nm: SymTab.Name);
  BEGIN CopyNm(instName, nm) END InstNameGet;

PROCEDURE InstActualGet (i: CARDINAL) : SymTab.TypeIndex;
  BEGIN
    IF i >= instN THEN RETURN SymTab.InvalidType END;
    RETURN instActual[i]
  END InstActualGet;

PROCEDURE InstBegin (name: ARRAY OF CHAR);
  BEGIN instActive := TRUE; CopyNm(name, instName); instN := 0;
    instFk := 0 END InstBegin;

PROCEDURE InstAddActual (t: SymTab.TypeIndex);
  BEGIN
    IF instN <= HIGH(instActual) THEN instActual[instN] := t; INC(instN) END
  END InstAddActual;

PROCEDURE InstEnd;
  BEGIN instActive := FALSE; instN := 0 END InstEnd;

PROCEDURE UnitNameGet (VAR nm: SymTab.Name);
  BEGIN CopyNm(unitName, nm) END UnitNameGet;

PROCEDURE UnitIsGeneric () : BOOLEAN;
  BEGIN RETURN unitWasGen END UnitIsGeneric;

PROCEDURE UnitIsDefModule () : BOOLEAN;
  BEGIN RETURN unitWasDef END UnitIsDefModule;

PROCEDURE RefineSeen () : BOOLEAN;
  BEGIN RETURN refSeen END RefineSeen;

PROCEDURE RefineIsDef () : BOOLEAN;
  BEGIN RETURN refIsDef END RefineIsDef;

PROCEDURE RefineInst (VAR nm: SymTab.Name);
  BEGIN CopyNm(refInst, nm) END RefineInst;

PROCEDURE RefineGen (VAR nm: SymTab.Name);
  BEGIN CopyNm(refGen, nm) END RefineGen;

PROCEDURE RefineActualCount () : CARDINAL;
  BEGIN RETURN refN END RefineActualCount;

PROCEDURE RefineActualGet (i: CARDINAL) : SymTab.TypeIndex;
  BEGIN
    IF i >= refN THEN RETURN SymTab.InvalidType END;
    RETURN refActual[i]
  END RefineActualGet;

PROCEDURE NoteLabel (nm: ARRAY OF CHAR);
(* Record a statement label; duplicate is 200. *)
  VAR i: CARDINAL;
  BEGIN
    i := 0;
    WHILE i < nLab DO
      IF SymTab.Equal(labNm[i], nm) THEN SemError(200); RETURN END;
      INC(i)
    END;
    IF nLab <= HIGH(labNm) THEN
      CopyNm(nm, labNm[nLab]); INC(nLab)
    END
  END NoteLabel;

PROCEDURE NoteGoto (nm: ARRAY OF CHAR);
  VAR i: CARDINAL;
  BEGIN
    i := 0;
    WHILE i < nGot DO
      IF SymTab.Equal(gotNm[i], nm) THEN RETURN END;
      INC(i)
    END;
    IF nGot <= HIGH(gotNm) THEN
      CopyNm(nm, gotNm[nGot]); INC(nGot)
    END
  END NoteGoto;

PROCEDURE CheckGotos;
(* At a procedure's END: every GOTO must name a label in that procedure. *)
  VAR i, j: CARDINAL; found: BOOLEAN;
  BEGIN
    i := 0;
    WHILE i < nGot DO
      found := FALSE; j := 0;
      WHILE (j < nLab) AND NOT found DO
        IF SymTab.Equal(labNm[j], gotNm[i]) THEN found := TRUE END;
        INC(j)
      END;
      IF NOT found THEN SemError(201) END;
      INC(i)
    END
  END CheckGotos;

PROCEDURE FlushPend;
(* Emit module-level globals whose forward type is now resolved. *)
  VAR k: CARDINAL;
  BEGIN
    k := 0;
    WHILE k < nPendVar DO
      INC(k)
    END;
    nPendVar := 0
  END FlushPend;

PROCEDURE AstAppend (kind: INTEGER; VAR head, tail: AST.Node;
                     item: AST.Node);
(* Appends `item` to a chunked sequence: each node holds up to
   AST.MaxChild-1 items; child[MaxChild-1] continues into the next
   chunk.  Unbounded, so blocks/decl sequences are not capped at 8. *)
  VAR n: AST.Node;
  BEGIN
    IF item = AST.NoNode THEN RETURN END;
    IF head = AST.NoNode THEN
      head := AST.MakeNode(kind); tail := head
    END;
    IF AST.NChild(tail) >= AST.MaxChild - 1 THEN
      n := AST.MakeNode(kind);
      AST.SetChild(tail, AST.MaxChild - 1, n);
      tail := n
    END;
    AST.SetChild(tail, AST.NChild(tail), item)
  END AstAppend;

PROCEDURE AstCallNode (callee: AST.Node) : AST.Node;
(* Builds NkCall(callee, actuals...) from astArgs/astNArgs.  The actuals
   are a chunked sequence (AstAppend): a call can have more than
   MaxChild-1 arguments (the generic ArgList has 9), and SetChild would
   silently drop the tail.  NkBlock marks the continuation chunks. *)
  VAR n, tail: AST.Node; j: CARDINAL;
  BEGIN
    n := AST.MakeNode(AST.NkCall);
    AST.SetChild(n, 0, callee);
    tail := n;
    j := 0;
    WHILE j < astNArgs DO
      AstAppend(AST.NkBlock, n, tail, astArgs[j]);
      INC(j)
    END;
    RETURN n
  END AstCallNode;



PROCEDURE GetUnit (): AST.Node;
(* The most recently parsed unit's AST root (for the Lower comparison). *)
  BEGIN
    RETURN astUnit
  END GetUnit;

PROCEDURE SetTwoPhase (b: BOOLEAN);
(* Driver switch for the two-phase parse probe (milestone 1). *)
  BEGIN
    twoPhaseParse := b
  END SetTwoPhase;

PROCEDURE TokIs (kw: ARRAY OF CHAR): BOOLEAN;
(* The current lookahead token's source text equals kw.  Compares text,
   not token codes, so grammar renumbering cannot desync the skipper. *)
  VAR tok: ARRAY [0 .. 63] OF CHAR;
  BEGIN
    M2S.GetName(M2S.nextPos, M2S.nextLen, tok);
    RETURN SymTab.Equal(tok, kw)
  END TokIs;

PROCEDURE Adv;
(* Advance one token: exactly the parser frame's Get for a grammar
   without pragmas (its pragma branch is empty and the scanner never
   returns a token above maxT, so the repeat loop runs once).  A
   separate name because the frame's Get is declared later in this
   module: a bare Get here would bind the imported M2S.Get (which takes
   a parameter) under single-pass compilers. *)
  BEGIN
    M2S.Get(sym);
    INC(errDist)
  END Adv;

PROCEDURE NoteSpan (pn: SymTab.Name; start: M2S.INT32);
(* Records an outermost body span for the re-parse pass (milestone 2).
   Diagnostic only for now: nothing consumes the table yet.  Declared
   before its caller: V3 resolves single-pass (declaration before use),
   with no forward tolerance for procedure calls. *)
  BEGIN
    IF nSpans > HIGH(spanName) THEN RETURN END;
    CopyNm(pn, spanName[nSpans]);
    spanStart[nSpans] := start;
    spanIdx[nSpans] := SymTab.DeferBody();
    INC(nSpans)
  END NoteSpan;

PROCEDURE Openers (): BOOLEAN;
(* TRUE when the current token opens a block that must be closed by an
   END (BEGIN is excluded: a block's BEGIN shares the declaration END;
   REPEAT..UNTIL and EXIT/RETURN need no END). *)
  BEGIN
    RETURN TokIs("MODULE") OR TokIs("PROCEDURE") OR TokIs("CLASS")
       OR TokIs("RECORD") OR TokIs("IF") OR TokIs("CASE")
       OR TokIs("WHILE") OR TokIs("FOR") OR TokIs("LOOP")
       OR TokIs("WITH")
  END Openers;

PROCEDURE DeferSkip (pn: SymTab.Name): BOOLEAN;
(* Phase 1 of the deferral: skip the body starting at the current token
   (the first token after the heading's ';') up to the matching END,
   verify the END's name, and LEAVE the scanner positioned exactly at
   that END (so Block's trailing "END" ident consumes it for real), with
   the span recorded for the re-parse pass.  On any inconsistency,
   restore the scanner and return FALSE so the caller parses normally. *)
  VAR depth, guard: CARDINAL;
    nm: SymTab.Name;
    ok: BOOLEAN;
    start, endPos: M2S.INT32;
  BEGIN
    deferredBody := FALSE;
    start := M2S.nextPos;
    M2S.PushPos;
    depth := 0; guard := 0; ok := TRUE;
    LOOP
      IF sym = 0 THEN ok := FALSE; EXIT END;
      IF TokIs("END") THEN
        IF depth = 0 THEN EXIT END;
        DEC(depth)
      ELSIF Openers() THEN
        INC(depth)
      END;
      Adv;
      INC(guard);
      IF guard > 1000000 THEN ok := FALSE; EXIT END
    END;
    IF ok THEN
      (* sym is the matching END; check the name after it, then seek back
         so Block sees END (its "END" ident then consumes it for real). *)
      endPos := M2S.nextPos;
      Adv;
      M2S.GetName(M2S.nextPos, M2S.nextLen, nm);
      IF (sym = 0) OR NOT SymTab.Equal(nm, pn) THEN ok := FALSE END;
      IF ok THEN
        M2S.SeekTo(endPos); Adv
      END
    END;
    IF ok THEN
      NoteSpan(pn, start);
      spanTy[nSpans - 1] := Lower.CurScopeProc();
      spanNode[nSpans - 1] := curProcNode;
      M2S.DropPos;   (* keep the scanner at END; discard the snapshot *)
      deferredBody := TRUE;
      RETURN TRUE
    ELSE
      M2S.PopPos;
      FileIO.WriteString(FileIO.StdOut, "twophase defer mismatch in ");
      FileIO.WriteString(FileIO.StdOut, pn);
      FileIO.WriteLn(FileIO.StdOut);
      RETURN FALSE
    END
  END DeferSkip;

CHARACTERS
  eol      = CHR(13) .
  lf       = CHR(10) .
  letter   = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" .
  digit    = "0123456789" .
  hexDigit = digit + "ABCDEFabcdef" .
  noQuote1 = ANY - "'" - eol .
  noQuote2 = ANY - '"' - eol .

IGNORE CHR(9) .. CHR(13)

COMMENTS FROM "(*" TO "*)" NESTED
COMMENTS FROM "//" TO lf

TOKENS
  ident   = letter { letter | digit | "_" } .
  integer = digit { digit }
          | digit { digit } CONTEXT("..")
          | "0x" hexDigit { hexDigit }
          | "0X" hexDigit { hexDigit } .
  real    = digit { digit } "." { digit }
            [ ( "E" | "e" ) [ "+" | "-" ] digit { digit } ] .
  string  = "'" { noQuote1 } "'"
          | '"' { noQuote2 } '"' .
  charConst = digit { digit } ( "C" | "c" ) .
  ustring = ( "U" | "u" ) ( "'" { noQuote1 } "'" | '"' { noQuote2 } '"' ) .

PRODUCTIONS
  M2
    = (. astCur := AST.NoNode; astStmt := AST.NoNode; astDecl := AST.NoNode; astImp := AST.NoNode; astImpTail := AST.NoNode;
                                           astImp := AST.NoNode;
                                           astImpTail := AST.NoNode;
                                           nSpans := 0;
                                           SymTab.DeferReset; .)
      Unit "." .
  (* Units: program modules compile fully; DEFINITION and
     IMPLEMENTATION modules parse + check now but lower in step 4
     (each ends with one 230); same for nested local modules. *)
  (* Generics (Increment 1): formal and actual parameters.  Formals are
     TYPE parameters only; actuals are type identifiers. *)
  GenericFormals
    = "(" GenericFormal { ";" GenericFormal } ")" .
  GenericFormal                         (. VAR nm: SymTab.Name; .)
    = GetIdent<nm>                      (. IF instActive THEN
                                             IF NOT SymTab.EnterTypeParamBound(nm,
                                                InstActualGet(instFk)) THEN
                                               SemError(200) END
                                           ELSIF NOT SymTab.EnterTypeParam(nm) THEN
                                             SemError(200) END;
                                           INC(instFk); .)
      { "," GetIdent<nm>                (. IF instActive THEN
                                             IF NOT SymTab.EnterTypeParamBound(nm,
                                                InstActualGet(instFk)) THEN
                                               SemError(200) END
                                           ELSIF NOT SymTab.EnterTypeParam(nm) THEN
                                             SemError(200) END;
                                           INC(instFk); .) }
      ":" "TYPE" .
  Actuals
    = Actual { "," Actual } .
  Actual                                (. VAR at: SymTab.TypeIndex; .)
    = TypeIdent<at>                     (. IF refN <= HIGH(refActual) THEN
                                             refActual[refN] := at; INC(refN)
                                           END; .) .
  Unit
    =                                   (. isGen := FALSE;
                                           allowDefer := FALSE;
                                           repassing := FALSE; .)
      [ "GENERIC"                       (. isGen := TRUE; .) ]
      ( DefUnit | ImplUnit | ProgModule ) .
  (* Step 4.3: one session compiles DEFINITION, its IMPLEMENTATION
     and one program (last) into one image. Units share the symbol
     table; imports materialize exported names. *)
  DefUnit                               (. VAR m1, m2, pn: SymTab.Name;
                                             g: SymTab.Name;
                                             astSeq, astTail, astProc: AST.Node; .)
    =                                   (. refN := 0; refSeen := FALSE; .)
      "DEFINITION" "MODULE"
      GetIdent<m1>                      (. IF instActive THEN InstNameGet(m1) END;
                                           IF instActive THEN
                                             IF NOT SymTab.Reenter(m1,
                                                    SymTab.UnitDef) THEN
                                               SemError(200) END
                                           ELSIF NOT SymTab.BeginDef(m1) THEN
                                             SemError(200) END;
                                           QbeGen.SetModule(m1);
                                           CopyNm(m1, unitName);
                                           unitWasGen := isGen
                                             AND NOT instActive;
                                           unitWasDef := TRUE; .)
      [ GenericFormals ]
      ( ";"
      { Import                        (. AstAppend(AST.NkDeclSeq,
                                             astImp, astImpTail, astDecl); .) }
      [ "EXPORT" [ "QUALIFIED" ]        (. (* definition-module export
                                              list: parsed, and the
                                              names are already exported
                                              by the module scope *) .)
        GetIdent<pn> { "," GetIdent<pn> } ";" ]
                                        (. astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      { ConstBlock                      (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .)
      | TypeBlock<TRUE>                 (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .)
      | VarBlock                        (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .)
      | ProcHeading<pn, SymTab.InvalidType> ";"
                                        (. (* a heading only: record it so
                                              Lower can replay it *)
                                           astProc := AST.MakeNode(AST.NkProcDecl);
                                           AST.SetOp(astProc, 0);
                                           AST.SetChild(astProc, 0,
                                             AST.MakeLeaf(AST.NkIdent, pn));
                                           AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astProc);
                                           Lower.NoteProcNode(astProc);
                                           Lower.ScopeLeave;
                                           SymTab.CloseProc;
                                           QbeGen.AbortFunc; .) }
                                        (. astUnit := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astUnit, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           AST.SetChild(astUnit, 1, astSeq);
                                           AST.SetChild(astUnit, 3, astImp);
                                           astDecl := AST.NoNode;
                                           astStmt := AST.NoNode; .)
      "END"
      GetIdent<m2>                      (. IF instActive THEN InstNameGet(m2) END;
                                           IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           SymTab.EndUnit; .)
      | "=" GetIdent<g> [ "(" Actuals ")" ] ";"
                                        (. CopyNm(m1, refInst);
                                           CopyNm(g, refGen);
                                           refSeen := TRUE; refIsDef := TRUE;
                                           astUnit := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astUnit, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           astDecl := AST.NoNode;
                                           astStmt := AST.NoNode; .)
        "END"
        GetIdent<m2>                    (. IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           SymTab.EndUnit; .) ) .
  ImplUnit                              (. VAR m1, m2: SymTab.Name;
                                             g: SymTab.Name;
                                             k: CARDINAL;
                                             rp: CARDINAL;
                                             rpOk: BOOLEAN;
                                             rErrs: INTEGER;
                                             rDecl, rStmt: AST.Node;
                                             rnm: SymTab.Name;
                                             rSym, rErr: CARDINAL;
                                             fname: SymTab.Name;
                                             unres: BOOLEAN;
                                             astNode: AST.Node; .)
    =                                   (. refN := 0; refSeen := FALSE; .)
      "IMPLEMENTATION" "MODULE"
      GetIdent<m1> (. IF instActive THEN InstNameGet(m1) END;
                     IF instActive THEN
                       IF NOT SymTab.Reenter(m1,
                              SymTab.UnitImpl) THEN
                         SemError(201) END
                     ELSIF NOT SymTab.BeginImpl(m1) THEN
                       SemError(201) END;
                     astStmt := AST.NoNode;
                     astDecl := AST.NoNode;
                     astImp := AST.NoNode;
                     astImpTail := AST.NoNode;
                     nPendVar := 0;
                     CopyNm(m1, unitName);
                     unitWasGen := isGen AND NOT instActive;
                     unitWasDef := FALSE;
                     QbeGen.SetModule(m1); .)
      [ GenericFormals ]
      ( ";"
      { Import                        (. AstAppend(AST.NkDeclSeq,
                                             astImp, astImpTail, astDecl); .) }
      DeclSeq                           (. astStmt := AST.NoNode; .)
      [ "BEGIN"                         (. FlushPend;
                                           k := 0;
                                           WHILE k < SymTab.FwdPending() DO
                                             SymTab.FwdInfo(k, fname, unres);
                                             IF unres THEN SemError(201) END;
                                             INC(k)
                                           END;
                                           SymTab.FwdClear;

                                           nLab := 0; nGot := 0; .)
        [ StatSeq ] ]
                                        (. IF twoPhaseParse THEN
                                             rSym := sym; rErr := errDist;
                                             rDecl := astDecl; rStmt := astStmt;
                                             M2S.PushPos;
                                             repassing := TRUE;
                                             rp := 0;
                                             WHILE rp < nSpans DO
                                               k := 0;
                                               WHILE (k <= HIGH(rnm))
                                                 AND (spanName[rp][k] # CHR(0)) DO
                                                 rnm[k] := spanName[rp][k]; INC(k)
                                               END;
                                               rnm[k] := CHR(0);
                                               M2S.SeekTo(spanStart[rp]);
                                               Adv;
                                               rpOk := SymTab.ReenterDeferred(spanIdx[rp]);
                                               IF NOT rpOk THEN
                                                 FileIO.WriteString(FileIO.StdOut,
                                                   "twophase reenter failed");
                                                 FileIO.WriteLn(FileIO.StdOut)
                                               END;
                                               Lower.ReenterScopeProc(spanTy[rp]);
                                               QbeGen.BeginFunc("");
                                               Block(rnm);
                                               AST.SetChild(spanNode[rp], 1, astStmt);
                                               AST.SetChild(spanNode[rp], 2, astBlkDecls);
                                               Lower.ScopeLeave;
                                               SymTab.CloseProc;
                                               QbeGen.EndFunc(SymTab.ProcRes(rnm));
                                               INC(rp)
                                             END;
                                             rErrs := M2S.errors;
                                             repassing := FALSE;
                                             M2S.PopPos;
                                             sym := rSym; errDist := rErr;
                                             M2S.errors := rErrs;

                                             astDecl := rDecl; astStmt := rStmt
                                           END; .)
      "END"
      GetIdent<m2>                      (. IF instActive THEN InstNameGet(m2) END;
                                           FlushPend;
                                           k := 0;
                                           WHILE k < SymTab.FwdPending() DO
                                             SymTab.FwdInfo(k, fname, unres);
                                             IF unres THEN SemError(201) END;
                                             INC(k)
                                           END;
                                           SymTab.FwdClear;

                                           astNode := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           AST.SetChild(astNode, 1, astDecl);
                                           AST.SetChild(astNode, 2, astStmt);
                                           AST.SetChild(astNode, 3, astImp);
                                           astUnit := astNode;
                                           IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           CheckGotos;
                                           SymTab.EndUnit; .)
      | "=" GetIdent<g> [ "(" Actuals ")" ] ";"
                                        (. CopyNm(m1, refInst);
                                           CopyNm(g, refGen);
                                           refSeen := TRUE; refIsDef := FALSE;
                                           astNode := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           astDecl := AST.NoNode;
                                           astStmt := AST.NoNode; .)
        "END"
        GetIdent<m2>                    (. IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           SymTab.EndUnit; .) ) .
  ProgModule                            (. VAR m1, m2: SymTab.Name;
                                             k: CARDINAL;
                                             rp: CARDINAL;
                                             rpOk: BOOLEAN;
                                             rErrs: INTEGER;
                                             rDecl, rStmt: AST.Node;
                                             rnm: SymTab.Name;
                                             rSym, rErr: CARDINAL;
                                             fname: SymTab.Name;
                                             unres: BOOLEAN;
                                             astNode: AST.Node; .)
    = "MODULE"
      GetIdent<m1> (. IF NOT SymTab.BeginProg(m1) THEN
                                             SemError(200) END;
                                           astStmt := AST.NoNode;
                                           astDecl := AST.NoNode;
                                           astImp := AST.NoNode;
                                           astImpTail := AST.NoNode;
                                           nPendVar := 0;
                                           QbeGen.SetModule(m1); .)
      [ Priority ]
      ";"
      { Import                        (. AstAppend(AST.NkDeclSeq,
                                             astImp, astImpTail, astDecl); .) }
      DeclSeq                           (. astStmt := AST.NoNode; .)
      [ "BEGIN"                         (. FlushPend;
                                           k := 0;
                                           WHILE k < SymTab.FwdPending() DO
                                             SymTab.FwdInfo(k, fname, unres);
                                             IF unres THEN SemError(201) END;
                                             INC(k)
                                           END;
                                           SymTab.FwdClear;

                                           nLab := 0; nGot := 0; .)
        [ StatSeq ] ]
                                        (. IF twoPhaseParse THEN
                                             rSym := sym; rErr := errDist;
                                             rDecl := astDecl; rStmt := astStmt;
                                             M2S.PushPos;
                                             repassing := TRUE;
                                             rp := 0;
                                             WHILE rp < nSpans DO
                                               k := 0;
                                               WHILE (k <= HIGH(rnm))
                                                 AND (spanName[rp][k] # CHR(0)) DO
                                                 rnm[k] := spanName[rp][k]; INC(k)
                                               END;
                                               rnm[k] := CHR(0);
                                               M2S.SeekTo(spanStart[rp]);
                                               Adv;
                                               rpOk := SymTab.ReenterDeferred(spanIdx[rp]);
                                               IF NOT rpOk THEN
                                                 FileIO.WriteString(FileIO.StdOut,
                                                   "twophase reenter failed");
                                                 FileIO.WriteLn(FileIO.StdOut)
                                               END;
                                               Lower.ReenterScopeProc(spanTy[rp]);
                                               QbeGen.BeginFunc("");
                                               Block(rnm);
                                               AST.SetChild(spanNode[rp], 1, astStmt);
                                               AST.SetChild(spanNode[rp], 2, astBlkDecls);
                                               Lower.ScopeLeave;
                                               SymTab.CloseProc;
                                               QbeGen.EndFunc(SymTab.ProcRes(rnm));
                                               INC(rp)
                                             END;
                                             rErrs := M2S.errors;
                                             repassing := FALSE;
                                             M2S.PopPos;
                                             sym := rSym; errDist := rErr;
                                             M2S.errors := rErrs;

                                             astDecl := rDecl; astStmt := rStmt
                                           END; .)
      "END"
      GetIdent<m2>                      (. IF instActive THEN InstNameGet(m2) END;
                                           FlushPend;
                                           k := 0;
                                           WHILE k < SymTab.FwdPending() DO
                                             SymTab.FwdInfo(k, fname, unres);
                                             IF unres THEN SemError(201) END;
                                             INC(k)
                                           END;
                                           SymTab.FwdClear;

                                           IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           astNode := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           AST.SetChild(astNode, 1, astDecl);
                                           AST.SetChild(astNode, 2, astStmt);
                                           AST.SetChild(astNode, 3, astImp);
                                           astUnit := astNode;
                                           CheckGotos;
                                           SymTab.EndUnit; .) .
  DeclSeq                               (. VAR astSeq, astTail: AST.Node; .)
    =                                   (. astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      { (. astDecl := AST.NoNode; .)
        ( ConstBlock | TypeBlock<FALSE> | VarBlock | ProcDecl ";"
        | NestedModule ";" | ClassItem ";" )
                                        (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .) }
                                        (. astDecl := astSeq; .) .
  (* Local module, Wirth form. Declarations lower like top-level ones
     (same QBE module prefix); a BEGIN body becomes an init function
     that main calls; the EXPORT list is hoisted into the enclosing
     scope at END. *)
  NestedModule                          (. VAR m1, m2: SymTab.Name;
                                             expNames: ARRAY [0 .. 63] OF SymTab.Name;
                                             expCount, k: CARDINAL;
                                             astNode, nImp, nImpTail:
                                               AST.Node; .)
    = "MODULE"
      GetIdent<m1>                      (. IF NOT SymTab.Enter(m1,
                                             SymTab.KindModule) THEN
                                             SemError(200) END;
                                           SymTab.PushScope;
                                           expCount := 0;
                                           astNode := AST.MakeNode(AST.NkUnit);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, m1));
                                           astStmt := AST.NoNode;
                                           astDecl := AST.NoNode;
                                           nImp := AST.NoNode;
                                           nImpTail := AST.NoNode; .)
      [ Priority ]
      ";"
      { Import                        (. AstAppend(AST.NkDeclSeq,
                                             nImp, nImpTail, astDecl); .) }
      [ "EXPORT" [ "QUALIFIED" ]
        GetIdent<expNames[expCount]>    (. INC(expCount); .)
        { "," GetIdent<expNames[expCount]>
                                        (. INC(expCount); .) }
        ";" ]
      DeclSeq                           (. astStmt := AST.NoNode; .)
      [ "BEGIN"                         (. astStmt := AST.NoNode;
                                           .)
        [ StatSeq ] ]
      "END"
      GetIdent<m2>                      (. AST.SetChild(astNode, 1, astDecl);
                                           AST.SetChild(astNode, 2, astStmt);
                                           AST.SetChild(astNode, 3, nImp);
                                           astDecl := astNode;
                                           IF NOT SymTab.Equal(m1, m2) THEN
                                             SemError(202) END;
                                           k := 0;
                                           WHILE k < expCount DO
                                             SymTab.ExportUp(expNames[k]);
                                             INC(k)
                                           END;
                                           SymTab.PopScope; .) .
  Priority
    = "[" integer "]"                   (. SemError(230); .) .
  (* Imports (4.3): FROM materializes the names (unqualified use);
     plain IMPORT only demands the module exists — qualified `L.x`
     materializes on first use (Design). *)
  (* Unknown modules stay unchecked stubs (legacy, so hand-written
     import lines don't fail); a known module's missing export is
     201. *)
  Import                                (. VAR n: SymTab.Name;
                                             astImport: AST.Node; .)
    = "FROM"
      GetIdent<n>                       (. astImport := AST.MakeNode(AST.NkImport);
                                           AST.SetChild(astImport, 0,
                                             AST.MakeLeaf(AST.NkIdent, n)); .)
      "IMPORT"
      ImpList<n, astImport> ";"         (. astDecl := astImport; .)
    | "IMPORT"                          (. astImport := AST.MakeNode(AST.NkImport); .)
      ImpModList<astImport> ";"         (. astDecl := astImport; .) .
  ImpList<mod: SymTab.Name; node: AST.Node>
                                        (. VAR n: SymTab.Name; .)
    = ImpName<mod, node>
      { "," ImpName<mod, node> } .
  (* Pervasive built-ins imported from SYSTEM (e.g. TSIZE) are
     accepted and ignored: the built-in applies regardless. *)
  ImpName<mod: SymTab.Name; node: AST.Node>
                                        (. VAR n: SymTab.Name; .)
    = GetIdent<n> (. AST.SetChild(node, AST.NChild(node),
                                             AST.MakeLeaf(AST.NkIdent, n));
                                           IF SymTab.Equal(mod, "libc") THEN
                                             (* intrinsic C library:
                                                permissive external *)
                                             IF NOT SymTab.DeclareCProc(n) THEN
                                               SemError(201) END;
                                             Lower.NoteCProc(n)
                                           ELSIF SymTab.ModKnown(mod) THEN
                                             IF NOT SymTab.ImportFrom(mod, n) THEN
                                               SemError(201)
                                             ELSE Lower.NoteImportedProc(n)
                                             END
                                           END; .)
    | ( "TSIZE" | "SIZE" | "ADR" | "HIGH" | "LEN"
      | "CHR" | "ORD" | "ORDL" | "VAL" | "ABS" | "CAP"
      | "UCHR" | "CHR8" | "UORD"
      | "INC" | "DEC" ) .
  ImpModList<node: AST.Node>            (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. AST.SetChild(node, AST.NChild(node),
                                             AST.MakeLeaf(AST.NkIdent, n)); .)
      { "," GetIdent<n>                 (. AST.SetChild(node, AST.NChild(node),
                                             AST.MakeLeaf(AST.NkIdent, n)); .) } .
  (* Opaque TYPE declarations (definition modules). The targetless
     alias resolves to InvalidType until step 4 completes it. *)
  (* Scalar-phase TYPEs: named types, integer subranges, enumerations.
     Opaque "TYPE T;" needs isDef (definition units); elsewhere 231.
     Composite forms (ARRAY/RECORD/SET/POINTER) arrive with step 3. *)
  TypeBlock<isDef: BOOLEAN>             (. VAR astSeq, astTail: AST.Node; .)
    = "TYPE"                            (. SymTab.BeginTypeBlock;
                                           astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      { (. astDecl := AST.NoNode; .)
        ( TypeItem<isDef> ";" | ClassItem ";" )
                                        (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .) }
                                        (. SymTab.EndTypeBlock;
                                           astDecl := astSeq; .) .
  TypeItem<isDef: BOOLEAN>              (. VAR n: SymTab.Name;
                                             t, op: SymTab.TypeIndex;
                                             astNode: AST.Node; .)
    = GetIdent<n>                       (. op := SymTab.OpaqueBase(n);
                                           IF op = SymTab.InvalidType THEN
                                             IF NOT SymTab.Enter(n,
                                                SymTab.KindType) THEN
                                               SemError(200) END
                                           END; .)
      ( "=" Type<t, FALSE> (. astNode := AST.MakeNode(AST.NkTypeDecl);
                                             AST.SetChild(astNode, 0,
                                               AST.MakeLeaf(AST.NkIdent, n));
                                             AST.SetTy(astNode, t);
                                             astDecl := astNode;
                                             IF op # SymTab.InvalidType THEN
                                             SymTab.SetTarget(op, t)
                                           ELSE SymTab.SetSymType(n, t)
                                           END; .)
      |                                 (. IF op # SymTab.InvalidType THEN
                                             (* stays opaque *)
                                           ELSIF NOT isDef THEN
                                             SemError(231)
                                           ELSE SymTab.SetSymType(n,
                                             SymTab.NewAlias()) END; .) ) .
  Type<VAR t: SymTab.TypeIndex; allowOpen: BOOLEAN>
    = TypeIdent<t> [ Subrange<t> ]     (* anchored subrange: T[lo..hi] *)
    | Subrange<t>
    | Enum<t>
    | ArrayType<t, allowOpen>
    | SetType<t>
    | RecordType<t>
    | PointerType<t>
    | ProcType<t> .
  PointerType<VAR t: SymTab.TypeIndex>  (. VAR base: SymTab.TypeIndex; .)
    = "POINTER" "TO" Type<base, FALSE>(. t := SymTab.NewPtr(base); .) .
  (* Procedure types (step 8.5): PROCEDURE (params): result. Values
     are code pointers; params are collected into the descriptor. *)
  ProcType<VAR t: SymTab.TypeIndex>     (. VAR res, pt: SymTab.TypeIndex;
                                             isV: BOOLEAN; .)
    = "PROCEDURE"                       (. res := SymTab.InvalidType;
                                           t := SymTab.NewProcType(res); .)
      [ "(" [ ProcTypeSection<t> { ";" ProcTypeSection<t> } ] ")" ]
      [ ":" TypeIdent<res>              (. SymTab.SetProcTypeRes(t, res); .) ] .
  ProcTypeSection<t: SymTab.TypeIndex>  (. VAR pt: SymTab.TypeIndex;
                                             isV: BOOLEAN;
                                             cnt, k: CARDINAL;
                                             names: ARRAY [0 .. 15] OF SymTab.Name; .)
    =                                   (. isV := FALSE; cnt := 0; .)
      [ "VAR"                           (. isV := TRUE; .) ]
      ( GetIdent<names[cnt]>            (. INC(cnt); .)
        { "," GetIdent<names[cnt]>      (. INC(cnt); .) }
        ( ":" Type<pt, TRUE>           (. k := 0;
                                           WHILE k < cnt DO
                                             SymTab.ProcTypeAdd(t, isV, pt);
                                             INC(k)
                                           END; .)
        |                               (. (* type-only parameter list:
                                              each name is a type (GNU
                                              shorthand used by the
                                              Coco/R scanner frame) *)
                                           k := 0;
                                           WHILE k < cnt DO
                                             IF SymTab.Lookup(names[k])
                                                AND ((SymTab.SymKind(names[k]) = SymTab.KindType)
  OR (SymTab.SymKind(names[k]) = SymTab.KindPredef)) THEN
                                               pt := SymTab.SymType(names[k])
                                             ELSE SemError(201);
                                               pt := SymTab.InvalidType
                                             END;
                                             SymTab.ProcTypeAdd(t, isV, pt);
                                             INC(k)
                                           END; .) )
      | Type<pt, TRUE>                 (. (* unnamed parameter (PIM):
                                              e.g. PROCEDURE (VAR ARRAY OF REAL) *)
                                           SymTab.ProcTypeAdd(t, isV, pt); .) ) .
  (* Arrays: "OF" without bounds is an open formal (allowed only
     where allowOpen); "[lo..hi, ...]" nests bounded levels inside
     out. Bounds are folded literals (int/char); anything else 230.
     Bare-type indices ("ARRAY Color OF") wait for enum ordinals. *)
  ArrayType<VAR t: SymTab.TypeIndex; allowOpen: BOOLEAN>
                                        (. VAR elem: SymTab.TypeIndex;
                                             ok: BOOLEAN;
                                             bnds, bndh: ARRAY [0 .. 7] OF INTEGER;
                                             nb, k: CARDINAL;
                                             idx: SymTab.TypeIndex;
                                             ilo, ihi: INTEGER; .)
    = "ARRAY"
      ( "OF" Type<elem, FALSE>          (. IF NOT allowOpen THEN
                                             SemError(230) END;
                                           t := SymTab.NewOpenArray(elem); .)
      | TypeIdent<idx> [ Subrange<idx> ]
        "OF" Type<elem, FALSE>          (. (* index-type array: the index
                                              type's ordinal bounds give the
                                              [lo..hi] pair *)
                                           IF SymTab.TypeBounds(idx, ilo,
                                              ihi)
                                           THEN t := SymTab.NewArrayB(elem,
                                                  ilo, ihi)
                                           ELSE SemError(230);
                                             t := SymTab.InvalidType
                                           END; .)
      | "["                             (. SymTab.BoundBegin; ok := TRUE; .)
        BoundPair<ok>
        { "," BoundPair<ok> }
        "]"                             (. (* snapshot before the element
                                              type, which reuses the bound
                                              buffer for a nested ARRAY *)
                                           nb := SymTab.BoundCount();
                                           k := 0;
                                           WHILE k < nb DO
                                             bnds[k] := SymTab.BoundLo(k);
                                             bndh[k] := SymTab.BoundHi(k);
                                             INC(k)
                                           END; .)
        "OF" Type<elem, FALSE>
                                        (. IF ok THEN
                                             k := nb;
                                             WHILE k > 0 DO
                                               DEC(k);
                                               elem := SymTab.NewArrayB(
                                                 elem, bnds[k], bndh[k])
                                             END;
                                             t := elem
                                           ELSE t := SymTab.InvalidType
                                           END; .) ) .
  BoundPair<VAR ok: BOOLEAN>            (. VAR tlo, thi: SymTab.TypeIndex;
                                             qlo, qhi: QbeGen.QVal;
                                             lo, hi: INTEGER;
                                             cl, cl2: INTEGER; .)
    = Expr<tlo, qlo> ".." Expr<thi, qhi>
                                        (. IF (tlo = SymTab.InvalidType)
                                            OR (thi = SymTab.InvalidType) THEN
                                           ok := FALSE
                                         ELSE cl := SymTab.ClassOf(tlo);
                                           cl2 := SymTab.ClassOf(thi);
                                           IF ((cl # SymTab.ClInt)
 AND (cl # SymTab.ClChar))
                                              OR ((cl2 # SymTab.ClInt)
 AND (cl2 # SymTab.ClChar)) THEN
                                             SemError(230); ok := FALSE
                                           ELSIF NOT SymTab.ConstInt(qlo, lo)
                                              OR NOT SymTab.ConstInt(qhi, hi)
                                              OR (lo > hi) THEN
                                             SemError(230); ok := FALSE
                                            ELSIF NOT SymTab.BoundAdd(lo, hi) THEN
                                              SemError(230); ok := FALSE
                                            END;
                                          END; .) .
  (* Sets: multi-word masks over bases ≤ 256 values (bool, char,
     bounded subranges; enums wait for ordinals, INTEGER is
     unbounded). Literals are SET OF [0..255]; assignment and
     comparison across suitable bases are lenient (masks over min
     words + zero-check extras), out-of-span literals are 222. *)
  SetType<VAR t: SymTab.TypeIndex>      (. VAR base: SymTab.TypeIndex;
                                             blo, bhi, bspan: INTEGER;
                                             bcls: INTEGER; .)
    = "SET" "OF" Type<base, FALSE>
                                        (. IF base = SymTab.InvalidType THEN
                                             t := SymTab.InvalidType
                                           ELSE bcls :=
                                                  SymTab.ClassOf(base);
                                             IF bcls = SymTab.ClBool THEN
                                               blo := 0; bspan := 2
                                             ELSIF bcls = SymTab.ClChar THEN
                                               blo := 0; bspan := 256
                                             ELSIF bcls = SymTab.ClEnum THEN
                                               blo := 0;
                                               bspan := VAL(INTEGER,
                                                 SymTab.EnumCount(base))
                                             ELSIF SymTab.SubBounds(base,
                                                     blo, bhi) THEN
                                               bspan := bhi - blo + 1
                                             ELSE bspan := 0 END;
                                             IF (bspan <= 0)
                                                OR (bspan > 65536) THEN
                                               SemError(230);
                                               t := SymTab.InvalidType
                                             ELSE t := SymTab.NewSet(base)
                                             END
                                           END; .) .
  (* Records: flat blobs; array fields are pointers to static
     descriptors (locked amendment), nested records inline. Field
     offsets static and declaration-ordered. *)
  (* Field list: plain fields and (optionally) one variant part.  The
     variant part is a `CASE ... END` item; because it starts with the
     CASE keyword it is unambiguously distinguishable from a field
     (which starts with an identifier). *)
  RecordType<VAR t: SymTab.TypeIndex>   (. VAR t2: SymTab.TypeIndex;
                                             tagOk: BOOLEAN; .)
    = "RECORD"                          (. t := SymTab.NewRecord(); .)
      [ RecItem<t> { ";" [ RecItem<t> ] } ]
      "END"                             (. SymTab.LayoutRecord(t); .) .
  RecItem<rec: SymTab.TypeIndex>        (. VAR tt: SymTab.TypeIndex; .)
    = RecField<rec>
    | CaseField<rec>                    (. SymTab.MarkVariant(rec); .) .
  (* A variant part: CASE tag : Type OF variants.  The layout overlays
     every branch from the tag slot (see SymTab.ComputeOffsets). *)
  CaseField<rec: SymTab.TypeIndex>      (. VAR tagT: SymTab.TypeIndex;
                                             tagN: SymTab.Name; .)
    = "CASE"                            (. SymTab.ResetFields(rec); .)
      GetIdent<tagN>                    (. IF NOT SymTab.FieldPending(rec,
                                             tagN) THEN
                                             SemError(200) END; .)
      ":" Type<tagT, FALSE>             (. IF (tagT # SymTab.InvalidType)
  AND NOT SymTab.IsOrdinal(tagT) THEN
                                             SemError(224)
                                           END;
                                           SymTab.FixPendingF(rec, tagT);
                                           SymTab.SetVariantTag(rec, tagN); .)
      "OF"
      RecFieldList<rec>
      { "|"                             (. SymTab.ResetFields(rec); .)
        RecFieldList<rec> }
      "END" .
  RecFieldList<rec: SymTab.TypeIndex>   (. VAR lt, lq: SymTab.TypeIndex;
                                             lv1, lv2: QbeGen.QVal; .)
    = VarLabel<lt, lv1> [ ".." VarLabel<lq, lv2> ] ":"
      RecField<rec> { ";" [ RecField<rec> ] } .
  (* Variant case label: a constant (or a constant range).  Values are
     not interpreted (the layout overlays regardless). *)
  VarLabel<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR lname: SymTab.Name; .)
    = ( ident                         (. LexName(lname);
                                           QbeGen.CopyOp("0", q);
                                           t := SymTab.IntType(); .)
      | integer                       (. LexString(lname);
                                           QbeGen.CopyOp("0", q);
                                           t := SymTab.IntType(); .)
      | charConst                     (. LexString(lname);
                                           QbeGen.CopyOp("0", q);
                                           t := SymTab.CharType(); .) ) .
  RecField<rec: SymTab.TypeIndex>       (. VAR n: SymTab.Name;
                                             t2: SymTab.TypeIndex; .)
    = RecIdents<rec> ":" Type<t2, FALSE>(. SymTab.FixPendingF(rec, t2); .) .
  RecIdents<rec: SymTab.TypeIndex>      (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF NOT SymTab.FieldPending(rec,
                                             n) THEN
                                             SemError(200) END; .)
      { "," GetIdent<n>                 (. IF NOT SymTab.FieldPending(rec,
                                             n) THEN
                                             SemError(200) END; .) } .
  TypeIdent<VAR t: SymTab.TypeIndex>    (. VAR n, qid: SymTab.Name;
                                             k: INTEGER;
                                             dotted: BOOLEAN; .)
    = GetIdent<n>                       (. dotted := FALSE;
                                           IF NOT SymTab.Lookup(n) THEN
                                             k := -1;
                                             t := SymTab.ForwardType(n);
                                             IF t = SymTab.InvalidType THEN
                                               SemError(201)
                                             END
                                           ELSE k := SymTab.SymKind(n);
                                             IF (k = SymTab.KindType)
                                                OR (k = SymTab.KindPredef) THEN
                                               t := SymTab.SymType(n)
                                             ELSE t := SymTab.InvalidType
                                             END
                                           END; .)
      [ "." GetIdent<qid>               (. dotted := TRUE;
                                           IF k = SymTab.KindModule THEN
                                             t := SymTab.QualType(n, qid);
                                             IF t = SymTab.InvalidType THEN
                                               SemError(201)
                                             END
                                           ELSE SemError(221);
                                             t := SymTab.InvalidType
                                           END; .) ]
                                        (. IF NOT dotted THEN
                                             IF (k = SymTab.KindModule)
                                                OR ((k # SymTab.KindType)
  AND (k # SymTab.KindPredef)
  AND (k # SymTab.KindImport)
  AND (k # -1)) THEN
                                               SemError(221)
                                             END
                                           END; .) .
  Subrange<VAR t: SymTab.TypeIndex>     (. VAR tlo, thi: SymTab.TypeIndex;
                                             qlo, qhi: QbeGen.QVal;
                                             lo, hi: INTEGER; .)
    = "[" Expr<tlo, qlo> ".." Expr<thi, qhi>
                                        (. IF (tlo = SymTab.InvalidType)
                                            OR (thi = SymTab.InvalidType) THEN
                                           t := SymTab.InvalidType
                                         ELSIF NOT SymTab.IsOrdinal(tlo)
                                            OR NOT SymTab.IsOrdinal(thi) THEN
                                           SemError(230);
                                           t := SymTab.InvalidType
                                         ELSIF NOT SymTab.ConstInt(qlo, lo)
                                            OR NOT SymTab.ConstInt(qhi, hi)
                                            OR (lo > hi) THEN
                                           SemError(230);
                                           t := SymTab.InvalidType
                                         ELSE t := SymTab.NewSubR(lo, hi)
                                         END; .)
      "]" .
  Enum<VAR t: SymTab.TypeIndex>         (. VAR n: SymTab.Name;
                                             ord: INTEGER;
                                             qv: QbeGen.QVal; .)
    = "("                               (. t := SymTab.NewEnum();
                                           ord := 0; .)
      GetIdent<n>                       (. IF NOT SymTab.Enter(n,
                                             SymTab.KindConst) THEN
                                             SemError(200) END;
                                           SymTab.SetSymType(n, t);
                                           QbeGen.IntStr(ord, qv);
                                           SymTab.SetSymVal(n, qv);
                                           Lower.NoteVar(n,
                                             SymTab.KindConst, t);
                                           Lower.NoteConstVal(qv);
                                           INC(ord); .)
      { "," GetIdent<n>                 (. IF NOT SymTab.Enter(n,
                                             SymTab.KindConst) THEN
                                             SemError(200) END;
                                           SymTab.SetSymType(n, t);
                                           QbeGen.IntStr(ord, qv);
                                           SymTab.SetSymVal(n, qv);
                                           Lower.NoteVar(n,
                                             SymTab.KindConst, t);
                                           Lower.NoteConstVal(qv);
                                           INC(ord); .) }
      ")"                               (. SymTab.SetEnumCount(t,
                                             VAL(CARDINAL, ord)); .) .
  (* Clarion-form classes (docs/OOP.txt): declaration + single
     inheritance + IMPLEMENTATION blocks. Scopes and member checks
     now; lowering (vtable, dispatch, THIS) later — one 230 per
     class/impl block. Methods end with ";" per the Table example
     (not "," as in the sketch). No underscores in identifiers. *)
  (* Single CLASS item in both loops: separating declaration from
     IMPLEMENTATION at the loop level needs 2-token lookahead
     (CLASS ident vs CLASS IMPLEMENTATION), which LL(1) cannot do.
     The second token decides after CLASS is consumed. A misplaced
     CLASS IMPLEMENTATION inside TYPE still parses (harmless: the
     whole unit ends 230 until lowering). *)
  ClassItem
    = "CLASS" ( "IMPLEMENTATION" ClassImplRest | ClassRest ) .
  ClassRest                             (. VAR cn, m2, pn: SymTab.Name;
                                             ct: SymTab.TypeIndex; .)
    = GetIdent<cn>                      (. IF NOT SymTab.Enter(cn,
                                             SymTab.KindType) THEN
                                             SemError(200) END;
                                           ct := SymTab.NewClass();
                                           SymTab.SetSymType(cn, ct);
                                           SymTab.PushClassScope(ct);
                                           astCls := AST.MakeNode(AST.NkClassDecl);
                                           AST.SetChild(astCls, 0,
                                             AST.MakeLeaf(AST.NkIdent, cn));
                                           astClsP := AST.NoNode;
                                           astClsPTail := AST.NoNode;
                                           astClsF := AST.NoNode;
                                           astClsFTail := AST.NoNode;
                                           astClsM := AST.NoNode;
                                           astClsMTail := AST.NoNode; .)
      [ Parents<ct> ]
      ";"
      { ClassField<ct> ";" }
      { MethodHeading<pn, SymTab.InvalidType> ";"
                                        (. Lower.ScopeLeave;
                                           SymTab.CloseProc;
                                           QbeGen.AbortFunc; .) }
      "END"
      GetIdent<m2>                      (. IF NOT SymTab.Equal(cn, m2) THEN
                                             SemError(202) END;
                                           SymTab.LayoutClass(ct);
                                           SymTab.PopScope;
                                           AST.SetChild(astCls, 1, astClsP);
                                           AST.SetChild(astCls, 2, astClsF);
                                           AST.SetChild(astCls, 3, astClsM);
                                           astDecl := astCls; .) .
  Parents<ct: SymTab.TypeIndex>         (. VAR p: SymTab.Name; .)
    = "(" Parent1<ct>
      { "," GetIdent<p>                 (. SemError(230); .) }
      ")" .
  Parent1<ct: SymTab.TypeIndex>         (. VAR p: SymTab.Name;
                                             pt: SymTab.TypeIndex; .)
    = GetIdent<p>                       (. IF NOT SymTab.Lookup(p) THEN
                                             SemError(201)
                                           ELSE pt := SymTab.SymType(p);
                                             IF SymTab.ClassOf(pt) #
                                                SymTab.ClClass THEN
                                               SemError(230)
                                             ELSE SymTab.SetParent(ct, pt)
                                             END
                                           END;
                                           AstAppend(AST.NkFieldDecl,
                                             astClsP, astClsPTail,
                                             AST.MakeLeaf(AST.NkIdent, p)); .) .
  ClassField<ct: SymTab.TypeIndex>      (. VAR n, rhs: SymTab.Name;
                                             t: SymTab.TypeIndex;
                                             astNode: AST.Node; .)
    = GetIdent<n>
      ( "=" GetIdent<rhs>               (. IF NOT SymTab.Enter(n,
                                             SymTab.KindConst) THEN
                                             SemError(200) END;
                                           astNode := AST.MakeNode(AST.NkConstDecl);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, n));
                                           AST.SetChild(astNode, 1,
                                             AST.MakeLeaf(AST.NkIdent, rhs));
                                           AstAppend(AST.NkFieldDecl,
                                             astClsF, astClsFTail, astNode);
                                           IF SymTab.Lookup(rhs) THEN
                                             SymTab.SetSymType(n,
                                               SymTab.SymType(rhs))
                                           END; .)
      |                                 (. IF NOT SymTab.FieldPending(ct,
                                             n) THEN
                                             SemError(200) END;
                                           astNode := AST.MakeNode(AST.NkVarDecl);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, n)); .)
        { "," GetIdent<n>               (. IF NOT SymTab.FieldPending(ct,
                                             n) THEN
                                             SemError(200) END;
                                           AST.SetChild(astNode,
                                             AST.NChild(astNode),
                                             AST.MakeLeaf(AST.NkIdent, n)); .) }
        ":" Type<t, FALSE>              (. SymTab.FixPendingF(ct, t);
                                           AST.SetTy(astNode, t);
                                           AstAppend(AST.NkFieldDecl,
                                             astClsF, astClsFTail, astNode); .) ) .
  MethodHeading<VAR pn: SymTab.Name; ct: SymTab.TypeIndex>
                                        (. VAR wantVirt: BOOLEAN; .)
    =                                   (. wantVirt := FALSE; .)
      [ "VIRTUAL"                       (. wantVirt := TRUE; .) ]
      ProcHeading<pn, ct>               (. IF wantVirt THEN
                                             SymTab.MarkVirtual END;
                                           astMethod := AST.MakeNode(AST.NkProcDecl);
                                           AST.SetChild(astMethod, 0,
                                             AST.MakeLeaf(AST.NkIdent, pn));
                                           IF wantVirt THEN
                                             AST.SetOp(astMethod, 3)
                                           ELSE AST.SetOp(astMethod, 0)
                                           END;
                                           AstAppend(AST.NkFieldDecl,
                                             astClsM, astClsMTail, astMethod); .) .
  ClassImplRest                         (. VAR cn, m2: SymTab.Name;
                                             ct: SymTab.TypeIndex; .)
    = GetIdent<cn>                      (. IF NOT SymTab.Lookup(cn) THEN
                                             SemError(201);
                                             ct := SymTab.InvalidType
                                           ELSE ct := SymTab.SymType(cn);
                                             IF SymTab.ClassOf(ct) #
                                                SymTab.ClClass THEN
                                               SemError(230);
                                               ct := SymTab.InvalidType
                                             END
                                           END;
                                           astCls := AST.MakeNode(AST.NkClassDecl);
                                           AST.SetOp(astCls, 1);
                                           AST.SetChild(astCls, 0,
                                             AST.MakeLeaf(AST.NkIdent, cn));
                                           astClsM := AST.NoNode;
                                           astClsMTail := AST.NoNode;
                                           astStmt := AST.NoNode;
                                           IF ct #
                                              SymTab.InvalidType THEN
                                             IF NOT SymTab.PushClassMembers(
                                                    ct) THEN
                                               SemError(230) END;
                                             SymTab.PushImplClass(ct)
                                           END; .)
      ";" { MethodImpl<ct> ";" }
                                        (. astStmt := AST.NoNode; .)
      [ "BEGIN"                         (. astStmt := AST.MakeNode(AST.NkBlock);
                                           .)
        [ StatSeq ] ]
      "END"
      GetIdent<m2>                      (. IF NOT SymTab.Equal(cn, m2) THEN
                                             SemError(202) END;
                                           SymTab.PopImplClass;
                                           SymTab.PopScope;
                                           AST.SetChild(astCls, 1, AST.NoNode);
                                           AST.SetChild(astCls, 2, astStmt);
                                           AST.SetChild(astCls, 3, astClsM);
                                           astDecl := astCls; .) .
  MethodImpl<ct: SymTab.TypeIndex>      (. VAR pn: SymTab.Name;
                                             thisQ: QbeGen.QVal;
                                             methRes: SymTab.TypeIndex; .)
    = MethodHeading<pn, ct> ";"
                                        (. IF (ct #
                                              SymTab.InvalidType)
 AND NOT SymTab.MethodExists(ct,
                                                  pn) THEN
                                             SemError(201) END; .)
      ( "FORWARD"                       (. AST.SetOp(astMethod, 1);
                                           SymTab.MarkFwd;
                                           QbeGen.AbortFunc;
                                           Lower.ScopeLeave;
                                           SymTab.CloseProc; .)
      |                                 (.
                                           (* bind the receiver: bare
                                              field names resolve
                                              against THIS *)
                                            QbeGen.CopyOp("@", thisQ);
                                           QbeGen.PushWith(thisQ); .)
        Block<pn>                       (. AST.SetChild(astMethod, 1, astStmt);
                                           AST.SetChild(astMethod, 2, astBlkDecls);
                                           QbeGen.PopWith;
                                           methRes := SymTab.CurRes();
                                           Lower.ScopeLeave;
                                           SymTab.CloseProc;
                                           QbeGen.EndFunc(methRes); .) ) .
  ConstBlock                            (. VAR astSeq, astTail: AST.Node; .)
    = "CONST"                           (. astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      { ConstDecl ";"                   (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .) }
                                        (. astDecl := astSeq; .) .
  ConstDecl                             (. VAR n: SymTab.Name;
                                             t: SymTab.TypeIndex;
                                             qv: QbeGen.QVal;
                                             cls: INTEGER;
                                             astNode: AST.Node; .)
    = GetIdent<n>                       (. IF NOT SymTab.Enter(n,
                                             SymTab.KindConst) THEN
                                             SemError(200) END; .)
      "="
      Expr<t, qv> (. astNode := AST.MakeNode(AST.NkConstDecl);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, n));
                                           AST.SetChild(astNode, 1, astCur);
                                           AST.SetTy(astNode, t);
                                           astDecl := astNode;
                                           Lower.NoteVar(n, SymTab.KindConst, t);
                                           Lower.NoteConstVal(qv);
                                           SymTab.SetSymType(n, t);
                                           cls := SymTab.ClassOf(t);
                                           IF (cls = SymTab.ClArray)
                                              OR (cls = SymTab.ClRecord)
                                              OR (cls = SymTab.ClClass)
                                              OR (cls = SymTab.ClStr)
                                              OR (cls = SymTab.ClUStr) THEN
                                             (* an aggregate/string
                                                constant: qv is its
                                                descriptor address; no
                                                scalar data *)
                                             SymTab.SetSymVal(n, qv)
                                           ELSIF NOT QbeGen.IsImm(qv) THEN
                                             SemError(230)
                                           ELSE
                                             SymTab.SetSymVal(n, qv);
                                           END; .) .
  VarBlock                              (. VAR astSeq, astTail: AST.Node; .)
    = "VAR"                             (. astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      { VarDecl ";"                     (. AstAppend(AST.NkDeclSeq,
                                             astSeq, astTail, astDecl); .) }
                                        (. astDecl := astSeq; .) .
  VarDecl                               (. VAR nm: SymTab.Name;
                                             t: SymTab.TypeIndex;
                                             i: CARDINAL;
                                             cls: INTEGER;
                                             astNode, astTail: AST.Node; .)
    = VarIdents ":"
      Type<t, FALSE> (. astNode := AST.MakeNode(AST.NkVarDecl);
                                           astTail := astNode;
                                           i := 0;
                                           WHILE i < SymTab.PendCount() DO
                                             SymTab.PendName(i, nm);
                                             Lower.NoteVar(nm, SymTab.KindVar, t);
                                             (* chunked: a VAR list can
                                                exceed AST.MaxChild *)
                                             AstAppend(AST.NkBlock,
                                               astNode, astTail,
                                               AST.MakeLeaf(AST.NkIdent, nm));
                                             INC(i)
                                           END;
                                           AST.SetTy(astNode, t);
                                           astDecl := astNode;
                                           cls := SymTab.ClassOf(t);
                                           IF (t # SymTab.InvalidType)
 AND NOT SymTab.IsUnresolved(t)
 AND (cls # SymTab.ClInt)
 AND (cls # SymTab.ClBool)
 AND (cls # SymTab.ClChar)
 AND (cls # SymTab.ClReal)
 AND (cls # SymTab.ClArray)
 AND (cls # SymTab.ClSet)
 AND (cls # SymTab.ClRecord)
 AND (cls # SymTab.ClPtr)
 AND (cls # SymTab.ClLong)
 AND (cls # SymTab.ClProc)
 AND (cls # SymTab.ClUChar)
 AND (cls # SymTab.ClUStr)
 AND (cls # SymTab.ClEnum)
 AND (cls # SymTab.ClClass) THEN
                                             SemError(230) END;
                                           IF QbeGen.LocFull() THEN
                                             SemError(233) END;
                                           i := 0;
                                           IF SymTab.IsUnresolved(t)
                                              AND NOT SymTab.InProc() THEN
                                             (* a forward-typed global:
                                                defer emission until the
                                                TYPE block completes *)
                                             AST.SetOp(astNode, 1);
                                             WHILE i < SymTab.PendCount() DO
                                               SymTab.PendName(i, nm);
                                               IF nPendVar <=
                                                  HIGH(pendVarName) THEN
                                                 pendVarName[nPendVar] := nm;
                                                 pendVarT[nPendVar] := t;
                                                 INC(nPendVar)
                                               END;
                                               INC(i)
                                             END
                                           ELSE
                                             WHILE i < SymTab.PendCount() DO
                                               SymTab.PendName(i, nm);
                                               INC(i)
                                             END
                                           END;
                                           (* a plain VAR list, not a
                                              heading: the signature
                                              result is discarded *)
                                           IF NOT SymTab.FixPending(t) THEN
                                           END; .) .
  VarIdents                             (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF NOT SymTab.EnterPending(n,
                                             SymTab.KindVar) THEN
                                             SemError(200) END; .)
      { ","
        GetIdent<n>                     (. IF NOT SymTab.EnterPending(n,
                                             SymTab.KindVar) THEN
                                             SemError(200) END; .) } .
  ParIdents<isV: BOOLEAN>               (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF NOT SymTab.EnterParam(n, isV) THEN
                                             SemError(200) END; .)
      { "," GetIdent<n>                 (. IF NOT SymTab.EnterParam(n, isV) THEN
                                             SemError(200) END; .) } .
  (* Procedure headings enter scopes/params/result and buffer the
     QBE header; bodies lower to functions (4.1, module level only).
     FORWARD marks; the body heading re-enters (signature compare
     deferred). Nested procedures parse + check, lowering = 4.2. *)
  ProcHeading<VAR pn: SymTab.Name; methCls: SymTab.TypeIndex>
                                        (. VAR t: SymTab.TypeIndex;
                                             mg: QbeGen.QVal; .)
    = "PROCEDURE"
      GetIdent<pn>                      (. IF methCls #
                                              SymTab.InvalidType THEN
                                           (* a method: resume the
                                              declared symbol (reuse
                                              its uid) *)
                                           IF NOT SymTab.ResumeMethod(
                                                methCls, pn) THEN
                                             SemError(200) END
                                           ELSIF NOT SymTab.EnterProc(pn) THEN
                                           IF NOT SymTab.ReenterProc(pn) THEN
                                             IF NOT SymTab.ResumeProc(pn) THEN
                                               SemError(200) END
                                             END
                                           END;
                                           Lower.ScopeEnter;
                                           Lower.NoteProc(pn,
                                             SymTab.ProcUid(pn),
                                             SymTab.InvalidType,
                                             SymTab.ProcDepthOf(pn),
                                             FALSE);
                                           QbeGen.BeginFunc("");
                                           IF methCls #
                                              SymTab.InvalidType THEN
                                             (* hidden THIS receiver:
                                                a VAR param of the
                                                class type, pushed as
                                                the WITH base *)
                                             IF NOT SymTab.EnterThisParam(
                                                  methCls) THEN
                                               SemError(200) END;
                                             IF NOT QbeGen.FuncParam(
                                                  "THIS", TRUE,
                                                  methCls) THEN
                                               SemError(233) END
                                           END; .)
      [ FormalParams ]
      [ ":" TypeIdent<t>                (. IF NOT SymTab.SetProcRes(t) THEN
                                             SemError(235) END;
                                           Lower.SetProcRes(t); .) ] .
  FormalParams
    = "(" [ ParamSection { ";" ParamSection } ] ")" .
  ParamSection                          (. VAR t: SymTab.TypeIndex;
                                             nm: SymTab.Name;
                                             i: CARDINAL;
                                             isV: BOOLEAN; .)
    =                                   (. isV := FALSE; .)
      [ "VAR"                           (. isV := TRUE; .) ]
      ParIdents<isV> ":" Type<t, TRUE>  (. i := 0;
                                           WHILE i < SymTab.PendCount() DO
                                             SymTab.PendName(i, nm);
                                             Lower.NoteParam(nm, t, isV);
                                             Lower.NoteVar(nm, SymTab.KindParam, t);
                                             (* value open arrays are
                                                passed as descriptor
                                                addresses (no copy):
                                                same representation as
                                                VAR formals *)
                                             IF NOT QbeGen.FuncParam(nm,
                                                  isV
                                                  OR SymTab.IsOpenArray(t),
                                                  t) THEN
                                               SemError(233) END;
                                             INC(i)
                                           END;
                                           IF NOT SymTab.FixPending(t) THEN
                                             SemError(235) END; .) .
  (* Nested procedures lower like top-level ones (4.2): the
     static link gives them their parent's frame. Methods keep
     parse-now/230-later. *)
  ProcDecl                              (. VAR pn: SymTab.Name;
                                             astNode: AST.Node; .)
    = ProcHeading<pn, SymTab.InvalidType> ";"
                                        (. astNode := AST.MakeNode(AST.NkProcDecl);
                                           AST.SetOp(astNode, 0);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, pn));
                                           Lower.NoteProcNode(astNode); .)
      ( "FORWARD"                       (. AST.SetOp(astNode, 1);
                                           astDecl := astNode;
                                           Lower.ScopeLeave;
                                           SymTab.MarkFwd;
                                           SymTab.CloseProc;
                                           QbeGen.AbortFunc; .)
      | "EXTERNAL"                      (. AST.SetOp(astNode, 2);
                                           astDecl := astNode;
                                           Lower.MarkProcExternal;
                                           Lower.ScopeLeave;
                                           SymTab.MarkExternal("");
                                           SymTab.CloseProc;
                                           QbeGen.AbortFunc; .)
      |                                 
        (. allowDefer := TRUE; deferredBody := FALSE;
                                           curProcNode := astNode; .)
        Block<pn>                       (. IF deferredBody THEN
                                             (* body skipped: close like
                                                FORWARD (no body node) *)
                                             astDecl := astNode;
                                             Lower.ScopeLeave;
                                             SymTab.CloseProc;
                                             QbeGen.AbortFunc
                                           ELSE
                                             AST.SetChild(astNode, 1, astStmt);
                                             AST.SetChild(astNode, 2, astBlkDecls);
                                             astDecl := astNode;
                                             Lower.ScopeLeave;
                                             SymTab.CloseProc;
                                             QbeGen.EndFunc(
                                               SymTab.ProcRes(pn))
                                           END; .) ) .
  Block<pn: SymTab.Name>                (. VAR m2: SymTab.Name; dfr: BOOLEAN; .)
    =                                   (. dfr := FALSE;
                                           IF allowDefer AND twoPhaseParse
                                              AND NOT repassing THEN
                                             dfr := DeferSkip(pn)
                                           END;
                                           allowDefer := FALSE;
                                           .)
      DeclSeq                           (. astBlkDecls := astDecl;
                                           astStmt := AST.NoNode;
                                           nLab := 0; nGot := 0; .)
      [ "BEGIN"                         (. (* an empty body is still a
                                             body: mark it so Lower
                                             does not read it as a
                                             definition heading *)
                                           IF NOT dfr THEN
                                             IF astStmt = AST.NoNode THEN
                                               astStmt :=
                                                 AST.MakeNode(AST.NkBlock)
                                             END
                                           END; .)
        [ StatSeq ] ]
      "END"
      GetIdent<m2>                      (. IF NOT SymTab.Equal(pn, m2) THEN
                                             SemError(202) END;
                                           CheckGotos; .) .
  (* Two-phase, phase 2 (milestone 2c): re-parse every deferred module-
     level body once the unit's declarations are complete.  Inlined at
     both call sites because a stand-alone epsilon production is
     "unreachable" to Coco/R (referenced only from actions). *)
  StatSeq                               (. VAR astSeq, astTail: AST.Node; .)
    =                                   (. astSeq := AST.NoNode;
                                           astTail := AST.NoNode; .)
      Statement                         (. AstAppend(AST.NkBlock,
                                             astSeq, astTail, astStmt); .)
      { ";" [ Statement                 (. AstAppend(AST.NkBlock,
                                             astSeq, astTail, astStmt); .) ] }
                                        (. astStmt := astSeq; .) .
  (* Trailing/empty statements (`a; ; b`, Coco/R's generated `;;`)
     are accepted: the statement after ';' is optional. *)
  Statement                             (. VAR lx: QbeGen.QVal; lxnm: SymTab.Name; .)
    = (. astStmt := AST.NoNode; .)
      ( AssOrCall
    | IfStat
    | WhileStat
    | RepeatStat
    | LoopStat
    | ForStat
    | CaseStat
    | WithStat
    | ReturnStat
    | HaltStat
    | NewStat
    | DisposeStat
    | IncDecStat
    | InclExclStat
    | "EXIT"                            (. IF NOT QbeGen.TopLoop(lx) THEN
                                             SemError(230) END;
                                           astStmt := AST.MakeNode(AST.NkExit); .)
    | "GOTO" GetIdent<lxnm>             (. NoteGoto(lxnm);
                                           astStmt := AST.MakeNode(AST.NkGoto);
                                           AST.SetChild(astStmt, 0,
                                             AST.MakeLeaf(AST.NkIdent, lxnm)); .) ) .
  (* INCL(set, elem) / EXCL(set, elem): PIM set-element builtins. *)
  InclExclStat                          (. VAR at, et2: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qe: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx, isInc: BOOLEAN;
                                             astNode, astD: AST.Node; .)
    = ( "INCL"                          (. isInc := TRUE; .)
      | "EXCL"                          (. isInc := FALSE; .) )
      "(" Design<at, dk, qd, qn, sfx> (. astD := astCur; .) ","
      Expr<et2, qe> ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
                                           IF isInc THEN
                                             AST.SetChild(astNode, 0,
                                               AST.MakeLeaf(AST.NkIdent, "INCL"))
                                           ELSE AST.SetChild(astNode, 0,
                                               AST.MakeLeaf(AST.NkIdent, "EXCL"))
                                           END;
                                           IF astD # AST.NoNode THEN
                                             AST.SetChild(astNode, 1, astD) END;
                                           IF astCur # AST.NoNode THEN
                                             AST.SetChild(astNode, 2, astCur) END;
                                           astStmt := astNode; .)
                                        (. IF (at # SymTab.InvalidType)
  AND (SymTab.ClassOf(at) # SymTab.ClSet) THEN
                                             SemError(222)
                                           END; .) .
  (* INC(v [,step]) / DEC(v [,step]) as builtin statements over an
     integer designator. *)
  IncDecStat                            (. VAR dt, et2: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qv, qn2, qstep:
                                               QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx, isInc: BOOLEAN;
                                             astNode, astD, astStep:
                                               AST.Node; .)
    =                                   (. isInc := TRUE; .)
      ( "INC"                           (. isInc := TRUE; .)
      | "DEC"                           (. isInc := FALSE; .) )
      "("                               (. astStep := AST.NoNode; .)
      Design<dt, dk, qd, qn, sfx> (. astD := astCur; .)
      [ "," Expr<et2, qstep> (. astStep := astCur; .) ]
      ")"                               (. astNode := AST.MakeNode(AST.NkCall);
                                           IF isInc THEN
                                             AST.SetChild(astNode, 0,
                                               AST.MakeLeaf(AST.NkIdent, "INC"))
                                           ELSE AST.SetChild(astNode, 0,
                                               AST.MakeLeaf(AST.NkIdent, "DEC"))
                                           END;
                                           IF astD # AST.NoNode THEN
                                             AST.SetChild(astNode, 1, astD) END;
                                           IF astStep # AST.NoNode THEN
                                             AST.SetChild(astNode, 2, astStep) END;
                                           astStmt := astNode; .)                               (. IF dt = SymTab.InvalidType THEN
                                           ELSIF (dk # SymTab.KindVar)
 AND (dk # SymTab.KindParam)
 AND (dk # SymTab.KindField) THEN
                                             SemError(210)
                                           ELSIF NOT SymTab.IsIntFamily(dt) THEN
                                             SemError(211)
                                           END; .) .
  (* NEW/DISPOSE as builtin statements (no call syntax until step 4).
     Targets are pointer designators; DISPOSE nils afterwards (safer
     than Wirth-undefined; documented). DISPOSE is shallow. *)
  NewStat                               (. VAR dt: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qm: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx: BOOLEAN;
                                             bt: SymTab.TypeIndex;
                                             astNode, astD: AST.Node; .)
    = "NEW" "(" Design<dt, dk, qd, qn, sfx> (. astD := astCur; .) ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, "NEW"));
                                           IF astD # AST.NoNode THEN
                                             AST.SetChild(astNode, 1, astD) END;
                                           astStmt := astNode; .)
                                         (. IF dt = SymTab.InvalidType THEN
                                            ELSIF (dk # SymTab.KindVar)
  AND (dk # SymTab.KindParam)
  AND (dk # SymTab.KindField) THEN
                                              SemError(210)
                                            ELSIF SymTab.ClassOf(dt) #
                                                  SymTab.ClPtr THEN
                                              SemError(219)
                                            END; .) .
  DisposeStat                           (. VAR dt: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qv: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx: BOOLEAN;
                                             astNode, astD: AST.Node; .)
    = "DISPOSE" "(" Design<dt, dk, qd, qn, sfx> (. astD := astCur; .) ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, "DISPOSE"));
                                           IF astD # AST.NoNode THEN
                                             AST.SetChild(astNode, 1, astD) END;
                                           astStmt := astNode; .)
                                         (. IF dt = SymTab.InvalidType THEN
                                            ELSIF (dk # SymTab.KindVar)
  AND (dk # SymTab.KindParam)
  AND (dk # SymTab.KindField) THEN
                                              SemError(210)
                                            ELSIF SymTab.ClassOf(dt) #
                                                  SymTab.ClPtr THEN
                                              SemError(219)
                                            END; .) .
  (* WITH pushes each record's fields (inner wins) plus its base
     address; field designators resolve through both stacks. *)
  WithStat                              (. VAR nW: CARDINAL;
                                             astNode: AST.Node; .)
    = "WITH"                            (. nW := 0;
                                           astNode := AST.MakeNode(AST.NkWith); .)
      WithItem<nW, astNode> { "," WithItem<nW, astNode> }
      "DO"                              (. astStmt := AST.NoNode; .)
      [ StatSeq ] "END"                 (. AST.SetChild(astNode,
                                           AST.NChild(astNode), astStmt);
                                           astStmt := astNode;
                                           WHILE nW > 0 DO
                                             SymTab.PopScope;
                                             QbeGen.PopWith;
                                             DEC(nW)
                                           END; .) .
  WithItem<VAR nW: CARDINAL; wnode: AST.Node>
                                        (. VAR dt: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qe: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx: BOOLEAN; .)
    = Design<dt, dk, qd, qn, sfx>
                                        (. IF astCur # AST.NoNode THEN
                                             AST.SetChild(wnode,
                                               AST.NChild(wnode), astCur) END;
                                           IF dt = SymTab.InvalidType THEN
                                           ELSIF (SymTab.ClassOf(dt) #
                                                  SymTab.ClRecord)
 AND (SymTab.ClassOf(dt) #
                                                 SymTab.ClClass) THEN
                                             SemError(215)
                                           ELSIF SymTab.PushRecord(dt) THEN
                                             QbeGen.PushWith(qd);
                                             INC(nW)
                                           END; .) .
  (* Assignment or procedure-statement call (4.1, module level).
     Bare `P;` is a syntax error; function-as-statement is 233. *)
  AssOrCall                             (. VAR dt, et: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qe, qt, ql: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             ct2, res0: SymTab.TypeIndex;
                                             q2, mg0: QbeGen.QVal;
                                             isR, conv, wconv: BOOLEAN;
                                             called, sfx: BOOLEAN;
                                             astLhs, astRes: AST.Node; mname: SymTab.Name; isM: BOOLEAN;
                                             n: SymTab.Name; astLab, astNode: AST.Node; .)
    = GetIdent<n>
      ( ":"                             (. NoteLabel(n);
                                           astNode := AST.MakeNode(AST.NkLabel);
                                           AST.SetChild(astNode, 0,
                                             AST.MakeLeaf(AST.NkIdent, n));
                                           astLab := AST.MakeNode(AST.NkBlock);
                                           AST.SetChild(astLab, 0, astNode); .)
        Statement                       (. IF astStmt # AST.NoNode THEN
                                             AST.SetChild(astLab, 1, astStmt) END;
                                           astStmt := astLab; .)
      | DesignTail<n, dt, dk, qd, qn, sfx>
      (. astLhs := astCur; astNArgs := 0; .)
      ( ":="
        Expr<et, qe>                    (. astStmt := AST.MakeBin(
                                             AST.NkAssign, 0, astLhs, astCur);
                                           IF (dt # SymTab.InvalidType)
 AND (dk # SymTab.KindVar)
 AND (dk # SymTab.KindParam)
 AND (dk # SymTab.KindField) THEN
                                           SemError(210)
                                         ELSIF NOT SymTab.Assignable(et,
                                                  dt) THEN
                                           SemError(210)
                                         ELSIF (dt # SymTab.InvalidType)
 AND (SymTab.ClassOf(dt) =
                                               SymTab.ClClass) THEN
                                           SemError(230) END;
                                         isR := (dt #
                                                 SymTab.InvalidType)
 AND (SymTab.ClassOf(dt)
                                                   = SymTab.ClReal);
                                         conv := isR
 AND SymTab.IsIntFamily(et);
                                         wconv := (dt #
                                                   SymTab.InvalidType)
 AND SymTab.IsLongFamily(dt)
 AND SymTab.IsIntFamily(et);
                                         IF ((dk = SymTab.KindVar)
                                             OR (dk = SymTab.KindParam)
                                             OR (dk = SymTab.KindField))
 AND (dt # SymTab.InvalidType)
 AND (et # SymTab.InvalidType)
 AND (SymTab.ClassOf(dt) #
                                               SymTab.ClClass) THEN
                                         END; .)
      | ArgList<qn, dt, qd, TRUE, TRUE, methCls, ct2, q2, called>
                                        (. astRes := AstCallNode(astLhs);
                                           sfx := FALSE; .)
        ( { ResultComp<ct2, q2, sfx, astRes, mname, methCls, isM> }
          ":=" Expr<et, qe>             (. astStmt := AST.MakeBin(
                                             AST.NkAssign, 0, astRes, astCur);
                                           IF NOT sfx THEN
                                             SemError(233)
                                           ELSIF (ct2 # SymTab.InvalidType)
  AND NOT SymTab.Assignable(et, ct2) THEN
                                             SemError(210)
                                           END; .)
        |                               (. IF ct2 #
                                             SymTab.InvalidType THEN
                                             SemError(233) END;
                                           astStmt := astRes; .) )
      |                                 (* bare `P;`: proper parameterless
                                            procedure call; anything else
                                            here is 233 (was a bare syntax
                                            error before 4.2) *)
                                        (. astStmt := AstCallNode(astLhs);
                                            IF (dk = SymTab.KindProc)
 AND NOT sfx THEN
                                             res0 := SymTab.ProcRes(qn);
                                             IF res0 #
                                                SymTab.InvalidType THEN
                                               SemError(233)
                                             ELSIF SymTab.ProcNPar(qn) #
                                                     0 THEN
                                               SemError(233)
                                             END
                                           ELSE SemError(233)
                                            END; .) ) ) .
  (* Actual-parameter list shared by statement and expression calls.
     want selects CallEnd's result handling; t/q carry the call
     value (statement calls discard). Arity/type failures are 233;
     evaluation code still emits so the .ssa stays assembleable. *)
  ArgList<pn: SymTab.Name; pt: SymTab.TypeIndex; callee: QbeGen.QVal;
          want: BOOLEAN; soft: BOOLEAN; methCls: SymTab.TypeIndex;
          VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal;
          VAR called: BOOLEAN>          (. VAR i, np: CARDINAL;
                                             vs: INTEGER;
                                             res: SymTab.TypeIndex;
                                             mg: QbeGen.QVal;
                                             ok, ind, isMeth, va: BOOLEAN; .)
    = "("                               (. called := TRUE;
                                           ok := TRUE;
                                           ind := FALSE;
                                           isMeth := methCls #
                                             SymTab.InvalidType;
                                           IF isMeth THEN
                                             res := SymTab.ClassMethodRes(methCls, pn)
                                           ELSIF SymTab.SymKind(pn) = SymTab.KindProc THEN
                                             res := SymTab.ProcRes(pn)
                                           ELSIF (pt # SymTab.InvalidType)
  AND (SymTab.ClassOf(pt) = SymTab.ClProc) THEN
                                             ind := TRUE;
                                             res := SymTab.ProcTypeRes(pt)
                                           ELSE SemError(233);
                                             ok := FALSE;
                                             res := SymTab.InvalidType
                                           END;
                                           i := 0; .)
      [ ActParam<pn, pt, ind, methCls, i>        (. INC(i); .)
        { "," ActParam<pn, pt, ind, methCls, i>  (. INC(i); .) } ]
      ")"                               (. IF ok THEN
                                             IF isMeth THEN
                                               np := SymTab.ClassMethodNPar(
                                                 methCls, pn)
                                             ELSIF ind THEN
                                               np := SymTab.ProcTypeNPar(pt)
                                             ELSE np := SymTab.ProcNPar(pn)
                                             END;
                                             va := (NOT isMeth) AND (NOT ind)
                                               AND (SymTab.SymKind(pn) =
                                                    SymTab.KindProc)
                                               AND SymTab.Varargs(pn);
                                             IF (i # np) AND NOT va THEN
                                               SemError(233); ok := FALSE
                                             END
                                           END;
                                           IF NOT ok THEN
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           ELSIF want THEN
                                             IF res =
                                                SymTab.InvalidType THEN
                                               IF NOT soft THEN SemError(233) END;
                                               t := SymTab.InvalidType;
                                               QbeGen.CopyOp("0", q)
                                             ELSE t := res;
                                                QbeGen.CopyOp("@", q)
                                             END
                                           ELSE
                                             IF res #
                                                SymTab.InvalidType THEN
                                               SemError(233)
                                             END;
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q);
                                           END; .) .
  (* One actual: VAR formals take recorded designator addresses
     (233 otherwise); value formals take converted expressions. *)
  ActParam<pn: SymTab.Name; pt: SymTab.TypeIndex; ind: BOOLEAN;
           methCls: SymTab.TypeIndex; i: CARDINAL>
                                        (. VAR at, ft: SymTab.TypeIndex;
                                             qe, qa, qt: QbeGen.QVal;
                                             isV, conv, va: BOOLEAN;
                                             cl: CHAR;
                                             savedN, aj: CARDINAL;
                                             savedArgs: ARRAY [0 .. 31]
                                               OF AST.Node;
                                             astActual: AST.Node; .)
    =                                   (. (* Parsing the actual can clobber
                                             the enclosing call's argument
                                             list (Factor resets astNArgs),
                                             so save/restore it. *)
                                           savedN := astNArgs; aj := 0;
                                           WHILE aj <= HIGH(astArgs) DO
                                             savedArgs[aj] := astArgs[aj];
                                             INC(aj)
                                           END; .)
      Expr<at, qe>                      (. astActual := astCur;
                                           astNArgs := savedN; aj := 0;
                                           WHILE aj <= HIGH(astArgs) DO
                                             astArgs[aj] := savedArgs[aj];
                                             INC(aj)
                                           END;
                                           IF astNArgs <= HIGH(astArgs) THEN
                                             astArgs[astNArgs] := astCur;
                                             INC(astNArgs)
                                           END;
                                           va := (NOT ind)
                                             AND (methCls =
                                                SymTab.InvalidType)
                                             AND (SymTab.SymKind(pn) =
                                                SymTab.KindProc)
                                             AND SymTab.Varargs(pn);
                                           IF ind THEN
                                             ft :=
                                               SymTab.ProcTypeParamType(pt,
                                                 i);
                                             isV :=
                                               SymTab.ProcTypeParamIsVar(pt,
                                                 i)
                                           ELSIF methCls #
                                              SymTab.InvalidType THEN
                                             ft :=
                                               SymTab.ClassMethodParamType(
                                               methCls, pn, i);
                                             isV :=
                                               SymTab.ClassMethodParamIsVar(
                                               methCls, pn, i)
                                           ELSE
                                             ft := SymTab.ParamType(pn, i);
                                             isV := SymTab.ParamIsVar(pn, i)
                                           END;
                                           IF (at = SymTab.InvalidType) THEN
                                           ELSIF ft = SymTab.InvalidType THEN
                                           ELSIF isV THEN
                                             IF (SymTab.ClassOf(at) = SymTab.ClChar)
  AND (SymTab.ClassOf(ft) = SymTab.ClArray)
  AND (SymTab.ClassOf(SymTab.ArrayElem(ft)) = SymTab.ClChar)
  AND QbeGen.IsImm(qe) THEN
                                             ELSIF (AST.Kind(astActual) #
                                                    AST.NkDesignator)
  AND (AST.Kind(astActual) # AST.NkStrLit) THEN
                                               SemError(233)
                                             ELSIF NOT SymTab.VarParamOk(at, ft) THEN
                                               SemError(233)
                                             END
                                           ELSE
                                             IF (SymTab.ClassOf(at) = SymTab.ClChar)
  AND (SymTab.ClassOf(ft) = SymTab.ClArray)
  AND (SymTab.ClassOf(SymTab.ArrayElem(ft)) = SymTab.ClChar)
  AND QbeGen.IsImm(qe) THEN
                                             ELSIF NOT SymTab.Assignable(at, ft) THEN
                                               SemError(233)
                                             END
                                           END; .) .
  IfStat                                (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             hasElse: BOOLEAN;
                                             astCond, astIf, astLast,
                                             astNode: AST.Node; .)
    = "IF" (. hasElse := FALSE; .)
      Expr<t, q> (. astCond := astCur; astStmt := AST.NoNode;
                                           IF NOT SymTab.BoolCheck(t) THEN
                                             SemError(214) END; .)
      "THEN" [ StatSeq ]                (. astNode := AST.MakeNode(AST.NkIf);
                                           AST.SetChild(astNode, 0, astCond);
                                           AST.SetChild(astNode, 1, astStmt);
                                           astIf := astNode;
                                           astLast := astNode; .)
      { "ELSIF"
        Expr<t, q> (. astCond := astCur; astStmt := AST.NoNode;
                                           IF NOT SymTab.BoolCheck(t) THEN
                                             SemError(214) END; .)
        "THEN" [ StatSeq ]              (. astNode := AST.MakeNode(AST.NkIf);
                                           AST.SetChild(astNode, 0, astCond);
                                           AST.SetChild(astNode, 1, astStmt);
                                           AST.SetChild(astLast, 2, astNode);
                                           astLast := astNode; .) }
      [ "ELSE"                          (. hasElse := TRUE;
                                           astStmt := AST.NoNode; .)
        [ StatSeq ] (. AST.SetChild(astLast, 2, astStmt); .) ]
      "END" (. astStmt := astIf; .) .
  WhileStat                             (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             astCond, astNode: AST.Node; .)
    = "WHILE" (. astStmt := AST.NoNode; .)
      Expr<t, q> (. astCond := astCur;
                                           IF NOT SymTab.BoolCheck(t) THEN
                                             SemError(214) END; .)
      "DO" [ StatSeq ]                  (. astNode := AST.MakeNode(AST.NkWhile);
                                           AST.SetChild(astNode, 0, astCond);
                                           AST.SetChild(astNode, 1, astStmt);
                                           astStmt := astNode; .)
      "END" .
  RepeatStat                            (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             astCond, astBody, astNode:
                                               AST.Node; .)
    = "REPEAT" (. astStmt := AST.NoNode; .)
      [ StatSeq ] (. astBody := astStmt; .)
      "UNTIL" Expr<t, q> (. astCond := astCur;
                                           astNode := AST.MakeNode(AST.NkRepeat);
                                           AST.SetChild(astNode, 0, astBody);
                                           AST.SetChild(astNode, 1, astCond);
                                           astStmt := astNode;
                                           IF NOT SymTab.BoolCheck(t) THEN
                                             SemError(214) END; .) .
  LoopStat                              (. VAR lEnd: QbeGen.QVal; astNode: AST.Node; .)
    = "LOOP"                            (. astStmt := AST.NoNode;
                                           QbeGen.NewLabel(lEnd);
                                           QbeGen.PushLoop(lEnd); .)
      [ StatSeq ]
      "END"                             (. astNode := AST.MakeNode(AST.NkLoop);
                                           AST.SetChild(astNode, 0, astStmt);
                                           astStmt := astNode;
                                           QbeGen.PopLoop; .) .
  (* FOR with static-sign BY (literal, non-zero; 220 otherwise).
     Runtime direction would need a compare-select; the literal
     sign picks cslew/csegew at "DO" time. *)
  ForStat                               (. VAR lv: SymTab.Name;
                                             tlo, thi, tby:
                                               SymTab.TypeIndex;
                                             qlo, qhi, qby, qt, qk, qb:
                                               QbeGen.QVal;
                                             lTop, lBody, lEnd:
                                               QbeGen.QVal;
                                             by: INTEGER;
                                             ok: BOOLEAN;
                                             astVar, astLo, astHi, astBy,
                                             astNode: AST.Node; .)
    = "FOR"                             (. by := 1; .)
      GetIdent<lv> (. astVar := AST.MakeLeaf(AST.NkIdent, lv);
                                           astStmt := AST.NoNode;
                                           astBy := AST.NoNode;
                                           ok := SymTab.Lookup(lv);
                                           IF NOT ok THEN
                                             SemError(201)
                                           ELSIF (SymTab.SymKind(lv) #
                                                  SymTab.KindVar)
 AND (SymTab.SymKind(lv) #
                                                 SymTab.KindParam) THEN
                                             SemError(220); ok := FALSE
                                           ELSIF NOT SymTab.IsIntFamily(
                                                   SymTab.SymType(lv)) THEN
                                             SemError(220); ok := FALSE
                                           END; .)
      ":=" Expr<tlo, qlo> (. astLo := astCur;
                                           IF NOT SymTab.IsIntFamily(tlo) THEN
                                             SemError(220); ok := FALSE
                                           END; .)
      "TO" Expr<thi, qhi> (. astHi := astCur;
                                           IF NOT SymTab.IsIntFamily(thi) THEN
                                             SemError(220); ok := FALSE
                                           END; .)
      [ "BY" Expr<tby, qby> (. astBy := astCur;
                                           IF (tby #
                                             SymTab.InvalidType)
 AND NOT SymTab.IsIntFamily(tby) THEN
                                             SemError(220); ok := FALSE
                                           END;
                                           IF NOT SymTab.ConstInt(qby, by) THEN
                                             SemError(230); by := 1
                                           ELSIF by = 0 THEN
                                             SemError(220); by := 1
                                           END; .) ]
      "DO"
      [ StatSeq ]
      "END" (. astNode := AST.MakeNode(AST.NkFor);
                                           AST.SetChild(astNode, 0, astVar);
                                           AST.SetChild(astNode, 1, astLo);
                                           AST.SetChild(astNode, 2, astHi);
                                           AST.SetChild(astNode, 3, astBy);
                                           AST.SetChild(astNode, 4, astStmt);
                                           astStmt := astNode;
                                           .) .
  CaseStat                              (. VAR tsel: SymTab.TypeIndex;
                                             qsel, lEnd: QbeGen.QVal;
                                             arm, astNode, astArms,
                                             astArmsTail: AST.Node; .)
    = "CASE" Expr<tsel, qsel>           (. astNode := AST.MakeNode(AST.NkCase);
                                           AST.SetChild(astNode, 0, astCur);
                                           astArms := AST.NoNode;
                                           astArmsTail := AST.NoNode;
                                           .)
      "OF" CaseAlt<tsel, qsel, lEnd, astArms, astArmsTail>
      { "|" CaseAlt<tsel, qsel, lEnd, astArms, astArmsTail> }
      [ "ELSE"                          (. astStmt := AST.NoNode; .)
        [ StatSeq ]                     (. arm := AST.MakeNode(AST.NkCaseArm);
                                           AST.SetOp(arm, 1);
                                           AST.SetChild(arm, 0, astStmt);
                                           AstAppend(AST.NkBlock,
                                             astArms, astArmsTail, arm); .) ]
      "END"                             (. AST.SetChild(astNode, 1, astArms);
                                           astStmt := astNode;
                                           .) .
  (* Compare-chain lowering: each alternative ends its match-tests
     with "jmp lAfter", so the no-match fallthrough skips the body:
     "cmp; jnz(lBody,lF); lF: ... ; jmp lAfter; lBody: S; jmp lEnd;
     lAfter:". Falls into the next alternative, ELSE, or END. *)
  CaseAlt<tsel: SymTab.TypeIndex; qsel: QbeGen.QVal;
          lEnd: QbeGen.QVal; VAR arms, armsTail: AST.Node>
                                        (. VAR arm: AST.Node; .)
    =                                   (. arm := AST.MakeNode(AST.NkCaseArm); .)
      CaseLabel<tsel, qsel, arm>
      { "," CaseLabel<tsel, qsel, arm> }
      ":"                               (. astStmt := AST.NoNode; .)
      [ StatSeq ]                       (. AST.SetChild(arm, AST.NChild(arm),
                                           astStmt);
                                           AstAppend(AST.NkBlock,
                                             arms, armsTail, arm);
                                           .) .
  CaseLabel<tsel: SymTab.TypeIndex; qsel: QbeGen.QVal;
            arm: AST.Node>
                                        (. VAR t2, t3: SymTab.TypeIndex;
                                             q2, q3, qc, qd, qe:
                                               QbeGen.QVal;
                                             astLab: AST.Node;
                                             lNext: QbeGen.QVal; .)
    = Expr<t2, q2> (. astLab := astCur;
                                           IF (t2 #
                                             SymTab.InvalidType)
 AND (tsel #
                                               SymTab.InvalidType)
 AND ((SymTab.ClassOf(t2) =
                                                SymTab.ClSet)
                                               OR (SymTab.ClassOf(tsel) =
                                                   SymTab.ClSet)) THEN
                                             SemError(230)
                                           ELSIF (t2 #
                                             SymTab.InvalidType)
 AND (tsel #
                                               SymTab.InvalidType)
 AND NOT SymTab.EqCheck(t2,
                                                 tsel) THEN
                                             SemError(213) END;
                                               IF NOT QbeGen.IsImm(q2) THEN
                                                 SemError(230)
                                               END; .)
      [ ".." Expr<t3, q3>               (. astLab := AST.MakeBin(
                                             AST.NkSubrange, 0, astLab, astCur);
                                           IF (t3 #
                                             SymTab.InvalidType)
 AND (tsel #
                                               SymTab.InvalidType)
 AND NOT SymTab.EqCheck(t3,
                                                 tsel) THEN
                                             SemError(213) END;
                                               IF NOT QbeGen.IsImm(q3) THEN
                                                 SemError(230)
                                               END; .) ]
                                        (. AST.SetChild(arm,
                                             AST.NChild(arm), astLab); .) .
  ReturnStat                            (. VAR t: SymTab.TypeIndex;
                                             q, qt: QbeGen.QVal;
                                             res: SymTab.TypeIndex;
                                             hadE, conv: BOOLEAN;
                                             astVal, astNode: AST.Node; .)
    = "RETURN"                          (. hadE := FALSE; astStmt := AST.NoNode; .)
      [ Expr<t, q> (. hadE := TRUE; astVal := astCur; .) ]
                                        (. astNode := AST.MakeNode(AST.NkReturn);
                                           IF hadE THEN
                                             AST.SetChild(astNode, 0, astVal)
                                           END;
                                           astStmt := astNode;
                                           conv := FALSE;
                                           IF NOT SymTab.InProc() THEN
                                             SemError(232)
                                           ELSE res := SymTab.CurRes();
                                             IF NOT hadE THEN
                                               IF res #
                                                  SymTab.InvalidType THEN
                                                 SemError(232)
                                               END
                                             ELSIF (res =
                                                    SymTab.InvalidType)
                                                OR (t #
                                                    SymTab.InvalidType)
 AND NOT SymTab.Assignable(t,
                                                     res) THEN
                                               SemError(232)
                                           END
                                           END; .) .
  HaltStat                              (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             astVal, astNode: AST.Node; .)
    = "HALT" (. astVal := AST.NoNode; .)
      [ "(" Expr<t, q> (. astVal := astCur; .) ")" ]
                                        (. astNode := AST.MakeNode(AST.NkHalt);
                                           IF astVal # AST.NoNode THEN
                                             AST.SetChild(astNode, 0, astVal)
                                           END;
                                           astStmt := astNode;
                                           .) .
  (* Designator: scalar loads, array addresses, and index suffixes.
     Each index descends one level (bounds-checked, trap on breach);
     nested levels reload the inner descriptor address. q ends as the
     value (scalars), the descriptor address (plain arrays), or the
     element address (indexed); sfx marks the indexed form. *)
  Design<VAR t: SymTab.TypeIndex; VAR k: INTEGER;
         VAR q: QbeGen.QVal; VAR qn: SymTab.Name; VAR sfx: BOOLEAN>
                                        (. VAR n: SymTab.Name; .)
    = GetIdent<n> DesignTail<n, t, k, q, qn, sfx> .
  (* The part of Design after the identifier: resolve it and walk the
     selectors.  Split out so a statement can decide between a label
     (`ident :`) and a designator (`ident := ...`) with one token. *)
  DesignTail<VAR n: SymTab.Name; VAR t: SymTab.TypeIndex; VAR k: INTEGER;
         VAR q: QbeGen.QVal; VAR qn: SymTab.Name; VAR sfx: BOOLEAN>
                                        (. VAR fn, mal: SymTab.Name;
                                             cls: INTEGER;
                                             ic: SymTab.TypeIndex;
                                             curT, it, eT, bt:
                                               SymTab.TypeIndex;
                                             iq, ql, qlo, qhi, qe:
                                               QbeGen.QVal;
                                             lo, hi: INTEGER;
                                             fo: INTEGER;
                                             isOpen: BOOLEAN;
                                             qb, cv: QbeGen.QVal;
                                             r: BOOLEAN;
                                              astDes, astSel: AST.Node; .)
    =                                   (. methCls := SymTab.InvalidType;
                                           QbeGen.CopyOp(n, qn);
                                           sfx := FALSE;
                                           IF NOT SymTab.Lookup(n) THEN
                                             (* a bare method name inside
                                                a CLASS IMPLEMENTATION
                                                is a sibling call on
                                                THIS *)
                                             ic := SymTab.CurImplClass();
                                             IF (ic #
                                                SymTab.InvalidType)
  AND SymTab.MethodExists(ic, n) THEN
                                               sfx := FALSE;
                                                QbeGen.CopyOp("@", q);
                                               methCls := ic;
                                               k := SymTab.KindProc;
                                               t := SymTab.InvalidType
                                             ELSIF SymTab.InProc() THEN
                                               (* not declared anywhere
                                                  in scope: with bodies
                                                  parsed at unit end this
                                                  is a genuine 201 (a
                                                  nested-local forward is
                                                  no longer tolerated). *)
                                               SemError(201);
                                               t := SymTab.InvalidType;
                                               k := -1;
                                               QbeGen.CopyOp("0", q)
                                             ELSE
                                               SemError(201);
                                               t :=
                                                 SymTab.InvalidType;
                                               k := -1;
                                               QbeGen.CopyOp("0", q)
                                             END
                                           ELSE
                                             t := SymTab.SymType(n);
                                             k := SymTab.SymKind(n);
                                             IF k = SymTab.KindConst THEN
                                               IF SymTab.Equal(n,
                                                  "TRUE") THEN
                                                 t := SymTab.BoolType();
                                                 QbeGen.CopyOp("1", q)
                                               ELSIF SymTab.Equal(n,
                                                  "FALSE") THEN
                                                 t := SymTab.BoolType();
                                                 QbeGen.CopyOp("0", q)
                                               ELSIF SymTab.Equal(n,
                                                  "NIL") THEN
                                                 QbeGen.CopyOp("0", q)
                                               ELSE
                                                 cls :=
                                                   SymTab.ClassOf(t);
                                                 IF (t #
                                                     SymTab.InvalidType)
 AND ((cls = SymTab.ClInt)
                                                    OR (cls
                                                        = SymTab.ClChar)
                                                    OR (cls
                                                        = SymTab.ClEnum)
                                                    OR (cls
                                                        = SymTab.ClReal)
                                                    OR (cls
                                                        = SymTab.ClLong)
                                                    OR (cls
                                                        = SymTab.ClNil)) THEN
                                                   IF cls = SymTab.ClNil THEN
                                                     QbeGen.CopyOp("0", q)
                                                   ELSIF ((cls
                                                       = SymTab.ClInt)
                                                     OR (cls
                                                       = SymTab.ClChar)
                                                     OR (cls
                                                       = SymTab.ClEnum)
                                                     OR (cls
                                                       = SymTab.ClLong))
  AND SymTab.GetSymVal(n, cv)
  AND QbeGen.IsImm(cv) THEN
                                                     QbeGen.CopyOp(cv, q)
                                                   ELSE
                                                     QbeGen.LoadVar(n,
                                                       cls = SymTab.ClReal,
                                                       q)
                                                   END
                                                 ELSIF (cls = SymTab.ClArray)
                                                    OR (cls = SymTab.ClRecord)
                                                    OR (cls = SymTab.ClClass)
                                                    OR (cls = SymTab.ClStr)
                                                    OR (cls = SymTab.ClUStr) THEN
                                                   (* aggregate constant:
                                                      its value IS the
                                                      descriptor address *)
                                                   IF SymTab.GetSymVal(n, cv) THEN
                                                     QbeGen.CopyOp(cv, q)
                                                   ELSE
                                                     QbeGen.CopyOp("0", q)
                                                   END
                                                 ELSE
                                                   IF t #
                                                      SymTab.InvalidType THEN
                                                     SemError(230)
                                                   END;
                                                   QbeGen.CopyOp("0", q)
                                                 END
                                               END
                                             ELSIF (k = SymTab.KindVar)
                                                OR (k = SymTab.KindParam) THEN
                                               cls := SymTab.ClassOf(t);
                                               IF (cls # SymTab.ClInt)
                                                  AND (cls # SymTab.ClBool)
                                                  AND (cls # SymTab.ClChar)
                                                  AND (cls # SymTab.ClUChar)
                                                  AND (cls # SymTab.ClEnum)
                                                  AND (cls # SymTab.ClReal)
                                                  AND (cls # SymTab.ClPtr)
                                                  AND (cls # SymTab.ClProc)
                                                  AND (cls # SymTab.ClLong)
                                                  AND (cls # SymTab.ClArray)
                                                  AND (cls # SymTab.ClSet)
                                                  AND (cls # SymTab.ClRecord)
                                                  AND (cls # SymTab.ClUStr)
                                                  AND (cls # SymTab.ClClass) THEN
                                                 SemError(230);
                                                 QbeGen.CopyOp("0", q)
                                               ELSE QbeGen.CopyOp("@", q)
                                               END
                                             ELSE QbeGen.CopyOp("0", q);
                                               IF k = SymTab.KindImport THEN
                                                 SemError(230)
                                               ELSIF k =
                                                  SymTab.KindProc THEN
                                                 (* bare procedure name:
                                                    a following ArgList
                                                    makes it a call;
                                                    otherwise Fact
                                                    reports 230 *)
                                               ELSE
                                                  IF k = SymTab.KindField THEN
                                                    IF QbeGen.TopWith(qb) THEN
                                                      sfx := TRUE
                                                    ELSE SemError(230);
                                                      QbeGen.CopyOp("0", q)
                                                    END
                                                  END
                                               END
                                             END
                                           END; .)
      (. astDes := AST.MakeNode(AST.NkDesignator);
         AST.SetChild(astDes, AST.NChild(astDes), AST.MakeLeaf(AST.NkIdent, n)); .)
      { "[" Expr<it, iq>
                                        (. AST.SetChild(astDes, AST.NChild(astDes),
             AST.MakeUn(AST.NkSelector, AST.SelIndex, astCur)); IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClArray THEN
                                             SemError(217);
                                             t := SymTab.InvalidType
                                           ELSIF NOT SymTab.IsIntFamily(it)
 AND (SymTab.ClassOf(it) #
                                                 SymTab.ClChar)
 AND (SymTab.ClassOf(it) #
                                                 SymTab.ClEnum) THEN
                                             SemError(218);
                                             t := SymTab.InvalidType
                                            ELSE
                                              eT := SymTab.ArrayElem(t);
                                              t := eT; sfx := TRUE
                                            END; .)
        { "," Expr<it, iq>
                                        (. AST.SetChild(astDes, AST.NChild(astDes),
             AST.MakeUn(AST.NkSelector, AST.SelIndex, astCur)); IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClArray THEN
                                             SemError(217);
                                             t := SymTab.InvalidType
                                           ELSIF NOT SymTab.IsIntFamily(it)
 AND (SymTab.ClassOf(it) #
                                                 SymTab.ClChar)
 AND (SymTab.ClassOf(it) #
                                                 SymTab.ClEnum) THEN
                                             SemError(218);
                                             t := SymTab.InvalidType
                                            ELSE
                                              eT := SymTab.ArrayElem(t);
                                              t := eT; sfx := TRUE
                                            END; .) }
        "]"
      | "." GetIdent<fn>
                                        (. astSel := AST.MakeNode(AST.NkSelector);
             AST.SetOp(astSel, AST.SelField);
             AST.SetChild(astSel, 0, AST.MakeLeaf(AST.NkIdent, fn));
             AST.SetChild(astDes, AST.NChild(astDes), astSel); IF k = SymTab.KindModule THEN
                                             (* qualified L.x: materialize
                                                the export, then load it *)
                                             IF NOT SymTab.MaterializeAlias(n,
                                                  fn, mal) THEN
                                               SemError(201);
                                               t := SymTab.InvalidType;
                                               QbeGen.CopyOp("0", q)
                                             ELSE
                                               QbeGen.CopyOp(mal, qn);
                                               t := SymTab.SymType(mal);
                                               k := SymTab.SymKind(mal);
                                               sfx := FALSE;
                                               IF k = SymTab.KindProc THEN
                                                 (* call: ArgList supplies
                                                    the value *)
                                                 QbeGen.CopyOp("0", q)
                                                END
                                             END
                                           ELSIF t = SymTab.InvalidType THEN
                                           ELSIF (SymTab.ClassOf(t) #
                                                  SymTab.ClRecord)
 AND (SymTab.ClassOf(t) #
                                                 SymTab.ClClass) THEN
                                             SemError(215);
                                             t := SymTab.InvalidType
                                           ELSIF (SymTab.ClassOf(t) =
                                                  SymTab.ClClass)
  AND SymTab.MethodExists(t, fn) THEN
                                             (* obj.Method: bind the
                                                method and pass obj as
                                                the hidden receiver; q
                                                already holds the
                                                object's address *)
                                             QbeGen.CopyOp(fn, n);
                                             QbeGen.CopyOp(fn, qn);
                                             methCls := t;
                                             k := SymTab.KindProc;
                                             t := SymTab.InvalidType
                                           ELSIF NOT SymTab.FieldExists(t,
                                                    fn) THEN
                                             SemError(216);
                                             t := SymTab.InvalidType
                                            ELSE
                                              t := SymTab.FieldType(t, fn);
                                              sfx := TRUE
                                            END; .)
      | "^"
                                        (. astSel := AST.MakeNode(AST.NkSelector);
             AST.SetOp(astSel, AST.SelDeref);
             AST.SetChild(astDes, AST.NChild(astDes), astSel); IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClPtr THEN
                                             SemError(219);
                                             t := SymTab.InvalidType
                                           ELSE
                                             bt := SymTab.PtrBase(t);
                                             IF bt = SymTab.InvalidType THEN
                                             ELSE
                                                t := bt;
                                                sfx := TRUE
                                              END
                                           END; .) } (. astCur := astDes; .) .
  (* Result suffix (ISO component after a function call): `F()^`,
     `F()[i]`, `F().field`.  The call result is in t/q with sfx FALSE
     (a value, or a descriptor address for aggregates); each component
     descends one level exactly like the Design components. *)
  ResultComp<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal;
             VAR sfx: BOOLEAN; VAR node: AST.Node;
             VAR mname: SymTab.Name; VAR methCls: SymTab.TypeIndex;
             VAR isM: BOOLEAN>          (. VAR it, eT, bt: SymTab.TypeIndex;
                                             iq, ql, qlo, qhi, qe, qb:
                                               QbeGen.QVal;
                                             lo, hi, fo: INTEGER;
                                             isOpen: BOOLEAN;
                                             fname: SymTab.Name;
                                             astWrap, astSel: AST.Node; .)
    = "[" Expr<it, iq>
                                        (. isM := FALSE;
                                           IF AST.Kind(node) # AST.NkDesignator THEN
                                             astWrap := AST.MakeNode(
                                               AST.NkDesignator);
                                             AST.SetChild(astWrap, 0, node);
                                             node := astWrap
                                           END;
                                           AST.SetChild(node, AST.NChild(node),
                                             AST.MakeUn(AST.NkSelector,
                                               AST.SelIndex, astCur)); IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClArray THEN
                                             SemError(217);
                                             t := SymTab.InvalidType
                                           ELSIF NOT SymTab.IsIntFamily(it)
  AND (SymTab.ClassOf(it) # SymTab.ClChar)
  AND (SymTab.ClassOf(it) # SymTab.ClEnum) THEN
                                             SemError(218);
                                             t := SymTab.InvalidType
                                            ELSE
                                              eT := SymTab.ArrayElem(t);
                                              t := eT; sfx := TRUE
                                            END; .)
      "]"
    | "." GetIdent<fname>
                                        (. isM := FALSE;
                                           IF AST.Kind(node) # AST.NkDesignator THEN
                                             astWrap := AST.MakeNode(
                                               AST.NkDesignator);
                                             AST.SetChild(astWrap, 0, node);
                                             node := astWrap
                                           END;
                                           AST.SetChild(node, AST.NChild(node),
                                             AST.MakeUn(AST.NkSelector,
                                               AST.SelField,
                                               AST.MakeLeaf(AST.NkIdent,
                                                 fname))); IF t = SymTab.InvalidType THEN
                                           ELSIF (SymTab.ClassOf(t) #
                                                  SymTab.ClRecord)
  AND (SymTab.ClassOf(t) # SymTab.ClClass) THEN
                                             SemError(215);
                                             t := SymTab.InvalidType
                                            ELSIF (SymTab.ClassOf(t) =
                                                   SymTab.ClClass)
  AND SymTab.MethodExists(t, fname) THEN
                                              (* a method on the call result:
                                                 a following ArgList makes
                                                 the call *)
                                              mname := fname;
                                              methCls := t; isM := TRUE;
                                              t := SymTab.InvalidType
                                           ELSIF NOT SymTab.FieldExists(t,
                                                    fname) THEN
                                             SemError(216);
                                             t := SymTab.InvalidType
                                            ELSE
                                              t := SymTab.FieldType(t, fname);
                                              sfx := TRUE
                                            END; .)
    | "^"                               (. isM := FALSE;
                                           IF AST.Kind(node) # AST.NkDesignator THEN
                                             astWrap := AST.MakeNode(
                                               AST.NkDesignator);
                                             AST.SetChild(astWrap, 0, node);
                                             node := astWrap
                                           END;
                                           astSel := AST.MakeNode(AST.NkSelector);
                                           AST.SetOp(astSel, AST.SelDeref);
                                           AST.SetChild(node,
                                             AST.NChild(node), astSel); IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClPtr THEN
                                             SemError(219);
                                             t := SymTab.InvalidType
                                           ELSE
                                             bt := SymTab.PtrBase(t);
                                             IF bt # SymTab.InvalidType THEN
                                                t := bt; sfx := TRUE
                                             END
                                           END; .) .
  Expr<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR t2: SymTab.TypeIndex;
                                             op: INTEGER;
                                             q2, qt, wl: QbeGen.QVal;
                                              astA, astB: AST.Node;
                                              astOp: INTEGER;
                                              astMade: BOOLEAN;
                                             isR: BOOLEAN; .)
    = SimExpr<t, q>                     (. astA := astCur; astMade := FALSE; .)
      [ Rel<op> SimExpr<t2, q2>
        (. astB := astCur; astMade := TRUE;
            astOp := AST.OpEq;
            IF op = SymTab.OpNeq1 THEN astOp := AST.OpNe
            ELSIF op = SymTab.OpNeq2 THEN astOp := AST.OpNe
            ELSIF op = SymTab.OpLt THEN astOp := AST.OpLt
            ELSIF op = SymTab.OpLe THEN astOp := AST.OpLe
            ELSIF op = SymTab.OpGt THEN astOp := AST.OpGt
            ELSIF op = SymTab.OpGe THEN astOp := AST.OpGe
            ELSIF op = SymTab.OpIn THEN astOp := AST.OpIn
            END;
            IF op = SymTab.OpIn THEN
             IF SymTab.InCheck(t, t2) THEN
               IF (t = SymTab.InvalidType)
                  OR (t2 = SymTab.InvalidType) THEN
                 t := SymTab.BoolType(); QbeGen.CopyOp("0", q)
               ELSE
                  t := SymTab.BoolType(); QbeGen.CopyOp("@", q)
               END
             ELSE SemError(222); t := SymTab.InvalidType;
               QbeGen.CopyOp("0", q)
             END
           ELSIF SymTab.RelCheck(t, t2, op) THEN
             IF (t = SymTab.InvalidType)
                OR (t2 = SymTab.InvalidType) THEN
               t := SymTab.BoolType(); QbeGen.CopyOp("0", q)
             ELSIF (SymTab.ClassOf(t) = SymTab.ClPtr)
                OR (SymTab.ClassOf(t2) = SymTab.ClPtr) THEN
               IF (op # SymTab.OpEq) AND (op # SymTab.OpNeq1)
 AND (op # SymTab.OpNeq2) THEN
                 SemError(213); t := SymTab.InvalidType;
                 QbeGen.CopyOp("0", q)
                ELSE
                  t := SymTab.BoolType(); QbeGen.CopyOp("@", q)
                END
              ELSIF (SymTab.ClassOf(t) = SymTab.ClSet)
                 OR (SymTab.ClassOf(t2) = SymTab.ClSet) THEN
                t := SymTab.BoolType(); QbeGen.CopyOp("@", q)
             ELSIF SymTab.StrCompat(t, t2) THEN
               QbeGen.StrEq(op, q, q2, qt);
               t := SymTab.BoolType(); QbeGen.CopyOp(qt, q)
             ELSIF SymTab.IsLongFamily(t)
                OR SymTab.IsLongFamily(t2) THEN
                t := SymTab.BoolType(); QbeGen.CopyOp("@", q)
              ELSE
                t := SymTab.BoolType();
                QbeGen.CopyOp("@", q)
              END
           ELSE SemError(213); t := SymTab.InvalidType;
              QbeGen.CopyOp("0", q)
            END;
            astCur := AST.MakeBin(AST.NkBinExpr, astOp, astA, astB); .) ]
       (. IF NOT astMade THEN astCur := astA END; .)
           (. IF astCur # AST.NoNode THEN AST.SetTy(astCur, t) END; .) .
  Rel<VAR op: INTEGER>
    = "="                               (. op := SymTab.OpEq; .)
    | "#"                               (. op := SymTab.OpNeq1; .)
    | "<"                               (. op := SymTab.OpLt; .)
    | "<="                              (. op := SymTab.OpLe; .)
    | ">"                               (. op := SymTab.OpGt; .)
    | ">="                              (. op := SymTab.OpGe; .)
    | "IN"                              (. op := SymTab.OpIn; .) .
  SimExpr<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR t2, res2, lt, rt:
                                               SymTab.TypeIndex;
                                             op: INTEGER;
                                             q2, qt, wq, qf, q2a, q2b:
                                               QbeGen.QVal;
                                             neg, isR, isL, folded:
                                               BOOLEAN;
                                             fok: BOOLEAN;
                                             lw, rw, mw: CARDINAL;
                                             lTrue, lNext, lDone, qr, qs: QbeGen.QVal;
                                              astA, astB: AST.Node;
                                              astSign, astOp: INTEGER; .)
    =                                   (. neg := FALSE; astSign := 0; .)
      [ "+"                         (. neg := TRUE; astSign := 1; .)
      | "-"                         (. neg := TRUE; astSign := -1; .) ]
      Term<t, q> (. astA := astCur;
                                          IF neg AND QbeGen.IsImm(q) THEN
                                            QbeGen.NegFold(q, q)
                                          END;
                                         IF astSign < 0 THEN
                                           astCur := AST.MakeUn(
                                             AST.NkUnary, AST.OpSub, astA);
                                           astA := astCur
                                         END; .)
       { AddOp<op>
         Term<t2, q2> (. astB := astCur; .)
        (. astOp := AST.OpAdd;
           IF op = SymTab.OpSub THEN astOp := AST.OpSub
           ELSIF op = SymTab.OpOr THEN astOp := AST.OpOr END;
           astA := AST.MakeBin(AST.NkBinExpr, astOp, astA, astB);
           astCur := astA;
           IF op = SymTab.OpOr THEN
             (* short-circuit: if q is true the RHS is skipped *)
             IF SymTab.BoolCheck(t) AND SymTab.BoolCheck(t2) THEN
               t := SymTab.BoolType()
             ELSE SemError(212); t := SymTab.InvalidType END;
              IF t # SymTab.InvalidType THEN
                QbeGen.CopyOp("@", q)
              ELSE QbeGen.CopyOp("0", q)
              END
           ELSIF (op = SymTab.OpAdd)
             AND (SymTab.UStrCompat(t, t2)
               OR ((SymTab.ClassOf(t) = SymTab.ClUChar)
                 AND (SymTab.ClassOf(t2) = SymTab.ClUStr))
               OR ((SymTab.ClassOf(t) = SymTab.ClUStr)
                 AND (SymTab.ClassOf(t2) = SymTab.ClUChar))
               OR ((SymTab.ClassOf(t) = SymTab.ClUChar)
                 AND (SymTab.ClassOf(t2) = SymTab.ClUChar))) THEN
             (* UString concatenation: a UCHAR operand becomes a
                1-codepoint UString; the result is a descriptor in the
                shim's concat buffer.  Work on copies so neither
                operand is clobbered. *)
              t := SymTab.NewUStr();
              QbeGen.CopyOp("@", q)
           ELSIF (op = SymTab.OpAdd)
             AND (SymTab.StrCompat(t, t2)
               OR (SymTab.IsStrType(t)
                 AND (SymTab.ClassOf(t2) = SymTab.ClChar))
               OR ((SymTab.ClassOf(t) = SymTab.ClChar)
                 AND SymTab.IsStrType(t2))) THEN
             (* string concatenation; a CHAR operand becomes a
                1-character string literal.  When both operands are
                constants, fold to a single string literal so a
                constructor element stays compile-time. *)
              QbeGen.StrFold(q, q2, SymTab.ClassOf(t), SymTab.ClassOf(t2),
                qt, fok);
              IF fok THEN QbeGen.CopyOp(qt, q)
              ELSE QbeGen.CopyOp("@", q)
              END;
              t := SymTab.NewStr()
           ELSIF (t # SymTab.InvalidType) AND (t2 # SymTab.InvalidType)
 AND (SymTab.ClassOf(t) = SymTab.ClSet)
 AND (SymTab.ClassOf(t2) = SymTab.ClSet) THEN
              lw := SymTab.SetWords(t); rw := SymTab.SetWords(t2);
              mw := lw;
              IF rw > mw THEN mw := rw END;
              t := SymTab.NewSet(
                     SymTab.NewSubR(0,
                       VAL(INTEGER, mw) * 32 - 1));
              QbeGen.CopyOp("@", q)
           ELSE
             IF SymTab.ArithCheck(t, t2, FALSE, res2) THEN
               lt := t; rt := t2; t := res2
             ELSE SemError(211); t := SymTab.InvalidType END;
             IF t # SymTab.InvalidType THEN
               isL := SymTab.IsLongFamily(t);
               isR := SymTab.ClassOf(t) = SymTab.ClReal;
               folded := FALSE;
               IF (NOT isL) AND (NOT isR)
  AND QbeGen.IsImm(q) AND QbeGen.IsImm(q2) THEN
                 IF op = SymTab.OpAdd THEN
                   folded := QbeGen.Fold2(0, q, q2, qf)
                 ELSE
                   folded := QbeGen.Fold2(1, q, q2, qf)
                 END
               END;
               IF folded THEN QbeGen.CopyOp(qf, q)
                ELSE
                QbeGen.CopyOp("@", q)
                END
             ELSE QbeGen.CopyOp("0", q)
             END
           END; .) }
           (. IF astCur # AST.NoNode THEN AST.SetTy(astCur, t) END; .) .
  AddOp<VAR op: INTEGER>
    = "+"                               (. op := SymTab.OpAdd; .)
    | "-"                               (. op := SymTab.OpSub; .)
    | "OR"                              (. op := SymTab.OpOr; .) .
  Term<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR t2, res2, lt, rt:
                                               SymTab.TypeIndex;
                                             op: INTEGER;
                                             q2, qt, wq, qf:
                                               QbeGen.QVal;
                                             isR, isL, folded: BOOLEAN;
                                             lw, rw, mw: CARDINAL;
                                             lNext, lFalse, lDone, qr, qs: QbeGen.QVal;
                                              astA, astB: AST.Node;
                                              astOp: INTEGER; .)
    = Fact<t, q> (. astA := astCur; .) { MulOp<op>
        Fact<t2, q2> (. astB := astCur; .)
      (. astOp := AST.OpMul;
         IF op = SymTab.OpSlash THEN astOp := AST.OpDiv
         ELSIF op = SymTab.OpDiv THEN astOp := AST.OpDiv
         ELSIF op = SymTab.OpMod THEN astOp := AST.OpMod
         ELSIF op = SymTab.OpAnd THEN astOp := AST.OpAnd END;
         astA := AST.MakeBin(AST.NkBinExpr, astOp, astA, astB);
         astCur := astA;
         IF op = SymTab.OpAnd THEN
           (* short-circuit: if q is false the RHS is skipped *)
           IF SymTab.BoolCheck(t) AND SymTab.BoolCheck(t2) THEN
             t := SymTab.BoolType()
           ELSE SemError(212); t := SymTab.InvalidType END;
            IF t # SymTab.InvalidType THEN QbeGen.CopyOp("@", q)
            ELSE QbeGen.CopyOp("0", q)
            END
         ELSIF (t # SymTab.InvalidType) AND (t2 # SymTab.InvalidType)
 AND (SymTab.ClassOf(t) = SymTab.ClSet)
 AND (SymTab.ClassOf(t2) = SymTab.ClSet) THEN
            lw := SymTab.SetWords(t); rw := SymTab.SetWords(t2);
            mw := lw;
            IF rw > mw THEN mw := rw END;
            t := SymTab.NewSet(
                   SymTab.NewSubR(0,
                     VAL(INTEGER, mw) * 32 - 1));
            QbeGen.CopyOp("@", q)
         ELSE
           IF SymTab.ArithCheck(t, t2,
                (op = SymTab.OpDiv) OR (op = SymTab.OpMod),
                res2) THEN
             lt := t; rt := t2; t := res2
           ELSE SemError(211); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             isL := SymTab.IsLongFamily(t);
             isR := SymTab.ClassOf(t) = SymTab.ClReal;
             folded := FALSE;
             IF (NOT isL) AND (NOT isR)
  AND QbeGen.IsImm(q) AND QbeGen.IsImm(q2) THEN
               IF op = SymTab.OpTimes THEN
                 folded := QbeGen.Fold2(2, q, q2, qf)
               ELSIF op = SymTab.OpDiv THEN
                 folded := QbeGen.Fold2(3, q, q2, qf)
               ELSIF op = SymTab.OpMod THEN
                 folded := QbeGen.Fold2(4, q, q2, qf)
               END
             END;
             IF folded THEN QbeGen.CopyOp(qf, q)
              ELSE
              QbeGen.CopyOp("@", q)
              END
           ELSE QbeGen.CopyOp("0", q)
           END
         END; .) }
           (. IF astCur # AST.NoNode THEN AST.SetTy(astCur, t) END; .) .
  MulOp<VAR op: INTEGER>
    = "*"                               (. op := SymTab.OpTimes; .)
    | "/"                               (. op := SymTab.OpSlash; .)
    | "DIV"                             (. op := SymTab.OpDiv; .)
    | "MOD"                             (. op := SymTab.OpMod; .)
    | ( "AND" | "&" )                   (. op := SymTab.OpAnd; .) .
  Fact<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR s: ARRAY [0 .. 255] OF CHAR;
                                             et, dt, t2, st, ct2, et2:
                                               SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, q2, sq, qa, qm0, qr, qt:
                                               QbeGen.QVal;
                                             qn, vn: SymTab.Name;
                                             vt: SymTab.TypeIndex;
                                             c1, c2: INTEGER;
                                             lo, hi: INTEGER;
                                             isMax: BOOLEAN;
                                             called, isHigh, sfx, isCh,
                                             isU, uok, isStr: BOOLEAN;
                                             ucp: INTEGER; astIsLit: BOOLEAN;
                                              astD: AST.Node;
                                              astCall: BOOLEAN;
                                              astNode, astNot: AST.Node;
                                              j: CARDINAL;
                                              astArg2: AST.Node;
                                              astBrace: AST.Node;
                                              astRes: AST.Node; mname: SymTab.Name; isM: BOOLEAN; .)
    = (. astIsLit := FALSE; .)
    ( integer                           (. LexString(s);
                                           QbeGen.NormInt(s, q); astIsLit := TRUE; astCur := AST.MakeLeaf(AST.NkIntLit, s);
                                           t := SymTab.IntType(); .)
    | charConst                         (. LexString(s);
                                           QbeGen.NormLit(s, q, isCh);
                                           astIsLit := TRUE;
                                           astCur := AST.MakeLeaf(
                                             AST.NkCharLit, s);
                                           t := SymTab.CharType(); .)
    | real                              (. LexString(s);
                                           QbeGen.NormReal(s, q);
                                           astIsLit := TRUE;
                                           astCur := AST.MakeLeaf(
                                             AST.NkRealLit, s);
                                           t := SymTab.RealType(); .)
    | string                            (. LexString(s);
                                           astIsLit := TRUE;
                                           astCur := AST.MakeLeaf(
                                             AST.NkStrLit, s);
                                           IF SymTab.StrLen(s) = 3 THEN
                                             t := SymTab.CharType();
                                             QbeGen.IntStr(
                                               QbeGen.CharVal(s), q)
                                           ELSE t := SymTab.NewStr();
                                             QbeGen.DeclStr(s, q);
                                             (* a literal's value IS its
                                                static descriptor address *)
                                           END; .)
    | ustring                           (. LexString(s);
                                           astIsLit := TRUE;
                                           astCur := AST.MakeLeaf(
                                             AST.NkStrLit, s);
                                           QbeGen.DeclUStr(s, q, isU, ucp,
                                             uok);
                                           IF NOT uok THEN
                                             SemError(234);
                                             t := SymTab.InvalidType
                                           ELSIF isU THEN
                                             t := SymTab.UCharType();
                                             QbeGen.IntStr(ucp, q)
                                           ELSE
                                             t := SymTab.NewUStr();
                                           END; .)
    | Design<dt, dk, qd, qn, sfx>       (. astD := astCur; astCall := FALSE; astBrace := AST.NoNode;
                                           astNArgs := 0; called := FALSE;
                                           t := dt;
                                           IF dk = SymTab.KindConst THEN
                                             QbeGen.CopyOp(qd, q)
                                           ELSE QbeGen.CopyOp("@", q)
                                           END; .)
      [ TypedBraceLit<dt, q>            (. t := dt; astCall := TRUE;
                                             astBrace := astCur; .) ]
      [ ArgList<qn, dt, qd, TRUE, FALSE, methCls, ct2, q2, called>
                                        (. astCall := TRUE;
                                           astNode := AstCallNode(astD);
                                           astRes := astNode;
                                           t := ct2;
                                           QbeGen.CopyOp(q2, q);
                                           sfx := FALSE; .)
        { ResultComp<t, q, sfx, astRes, mname, methCls, isM>
          [ (. astNArgs := 0; .)
            ArgList<mname, t, q, TRUE, FALSE, methCls, ct2, q2, called>
                                        (. astNode := AstCallNode(astRes);
                                           astRes := astNode;
                                           t := ct2;
                                           QbeGen.CopyOp(q2, q);
                                           sfx := FALSE; .) ] }
                                        (. IF sfx THEN
                                             IF t = SymTab.InvalidType THEN
                                               QbeGen.CopyOp("0", q)
                                             ELSIF (SymTab.ClassOf(t) #
                                                    SymTab.ClRecord)
  AND (SymTab.ClassOf(t) # SymTab.ClSet)
  AND (SymTab.ClassOf(t) # SymTab.ClArray)
  AND (SymTab.ClassOf(t) # SymTab.ClClass) THEN
                                                QbeGen.CopyOp("@", q)
                                             END
                                           END; .) ]
                                        (. IF called THEN
                                             astCur := astRes
                                           ELSIF astCall THEN
                                             astCur := astBrace
                                           ELSE astCur := astD
                                           END;
                                            astIsLit := TRUE;
                                            IF NOT called
 AND (dk = SymTab.KindProc) THEN
                                             (* bare zero-arg function
                                                call (parentheses may be
                                                omitted); a proper or
                                                parameterised proc here
                                                is 230 *)
                                              IF (SymTab.ProcNPar(qn) = 0)
 AND (SymTab.ProcRes(qn) # SymTab.InvalidType) THEN
                                                t := SymTab.ProcRes(qn);
                                                QbeGen.CopyOp("@", q);
                                                astCur := AST.MakeNode(AST.NkCall);
                                                AST.SetChild(astCur, 0, astD)
                                              ELSE
                                                t := SymTab.ProcTypeOf(qn);
                                                QbeGen.CopyOp("@", q)
                                              END
                                           END; .)
    | ( "HIGH"                          (. isHigh := TRUE; .)
      | ( "LEN" | "LENGTH" )            (. isHigh := FALSE; .) )
      "(" ( Design<dt, dk, qd, qn, sfx> (. isStr := FALSE;
                                            isU := FALSE; .)
          | string                       (. LexString(s); astCur := AST.MakeLeaf(AST.NkStrLit, s);
                                            isStr := TRUE;
                                            isU := FALSE;
                                            IF SymTab.StrLen(s) = 3 THEN
                                              dt := SymTab.CharType();
                                              QbeGen.IntStr(QbeGen.CharVal(s),
                                                qd)
                                            ELSE
                                              dt := SymTab.NewStr();
                                              QbeGen.DeclStr(s, qd);
                                            END;
                                            dk := -1;
                                            qn[0] := CHR(0); .)
          | ustring                      (. LexString(s); astCur := AST.MakeLeaf(AST.NkStrLit, s);
                                            QbeGen.DeclUStr(s, qd, isU, ucp,
                                              uok);
                                            isStr := FALSE;
                                            IF NOT uok THEN
                                              SemError(234);
                                              dt := SymTab.InvalidType
                                            ELSIF isU THEN
                                              (* one codepoint: a UCHAR;
                                                 LEN is 1, HIGH is 0 *)
                                              dt := SymTab.UCharType();
                                              QbeGen.IntStr(ucp, qd)
                                            ELSE
                                              dt := SymTab.NewUStr();
                                            END;
                                            dk := -1;
                                            qn[0] := CHR(0); .) )
      ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
   IF isHigh THEN AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "HIGH"))
   ELSE AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "LEN")) END;
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE;
                                           IF (dt # SymTab.InvalidType)
  AND (SymTab.ClassOf(dt) = SymTab.ClUStr) THEN
                                             (* UString: the count is
                                                the descriptor header *)
                                              t := SymTab.IntType();
                                              QbeGen.CopyOp("@", q)
                                           ELSIF (dt # SymTab.InvalidType)
  AND (SymTab.ClassOf(dt) = SymTab.ClUChar) THEN
                                             (* single UCHAR codepoint *)
                                             IF isHigh THEN
                                               QbeGen.CopyOp("0", qr)
                                             ELSE
                                               QbeGen.CopyOp("1", qr)
                                             END;
                                             t := SymTab.IntType();
                                             QbeGen.CopyOp(qr, q)
                                           ELSIF isStr THEN
                                             (* fold: content length at
                                                compile time *)
                                             IF SymTab.StrLen(s) = 3 THEN
                                               c1 := 1
                                             ELSE
                                               c1 :=
                                                 SymTab.StrLen(s) - 2
                                             END;
                                             IF isHigh THEN
                                               DEC(c1)
                                             END;
                                             QbeGen.IntStr(c1, qr);
                                             t := SymTab.IntType();
                                             QbeGen.CopyOp(qr, q)
                                           ELSIF dt = SymTab.InvalidType THEN
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           ELSIF SymTab.ClassOf(dt) #
                                                 SymTab.ClArray THEN
                                             SemError(217);
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           ELSE
                                              IF SymTab.IsOpenArray(dt) THEN
                                                t := SymTab.IntType();
                                                QbeGen.CopyOp("@", q)
                                              ELSE
                                                IF isHigh THEN
                                                  QbeGen.IntStr(
                                                    SymTab.ArrayHi(dt), qr)
                                                ELSE
                                                  QbeGen.IntStr(VAL(
                                                    INTEGER,
                                                    SymTab.ArrayLen(dt)),
                                                    qr)
                                                END;
                                                t := SymTab.IntType();
                                                QbeGen.CopyOp(qr, q)
                                              END
                                            END; .)
    | ( "SIZE" | "TSIZE" ) "(" Design<dt, dk, qd, qn, sfx> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "SIZE"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF dt = SymTab.InvalidType THEN
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           ELSE
                                             QbeGen.IntStr(VAL(INTEGER,
                                               SymTab.ObjectSize(dt)), q);
                                             t := SymTab.IntType()
                                           END; .)
    | ( "SHIFT"                         (. isMax := FALSE; .)
      | "ROTATE"                        (. isMax := TRUE; .) )
      "(" Expr<et, q> (. astArg2 := astCur; .) "," Expr<et2, q2> ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
   IF isMax THEN AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "ROTATE"))
   ELSE AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "SHIFT")) END;
   IF astArg2 # AST.NoNode THEN AST.SetChild(astNode, 1, astArg2) END;
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 2, astCur) END;
   astCur := astNode; astIsLit := TRUE;
                                           (* set shift/rotate: isMax
                                              doubles as "rotate" *)
                                           IF (et # SymTab.InvalidType)
                                              AND (SymTab.ClassOf(et) =
                                                 SymTab.ClSet) THEN
                                              t := et;
                                              QbeGen.CopyOp("@", q)
                                           ELSE SemError(230);
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           END; .)
    | ( "MIN"                           (. isMax := FALSE; .)
      | "MAX"                           (. isMax := TRUE; .) )
      "(" Design<dt, dk, qd, qn, sfx> ")"
                                        (. astNode := AST.MakeNode(AST.NkCall);
   IF isMax THEN AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "MAX"))
   ELSE AST.SetChild(astNode, 0,
     AST.MakeLeaf(AST.NkIdent, "MIN")) END;
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE;
                                           IF (dt # SymTab.InvalidType)
 AND (SymTab.ClassOf(dt) = SymTab.ClReal) THEN
                                             (* REAL/LONGREAL: the
                                                implementation bounds *)
                                             IF isMax THEN
                                               QbeGen.NormReal(
                                                 "3.402823e38", q)
                                             ELSE QbeGen.NormReal(
                                                 "-3.402823e38", q)
                                             END;
                                             t := SymTab.RealType()
                                           ELSIF (dt #
                                              SymTab.InvalidType)
 AND (SymTab.ClassOf(dt) =
                                                 SymTab.ClLong) THEN
                                             IF isMax THEN
                                               QbeGen.CopyOp(
                                                 "9223372036854775807", q)
                                             ELSE QbeGen.CopyOp(
                                                 "-9223372036854775808", q)
                                             END;
                                             t := SymTab.LongType()
                                           ELSIF SymTab.TypeBounds(dt, lo,
                                                    hi) THEN
                                             IF isMax THEN
                                               QbeGen.IntStr(hi, q)
                                             ELSE QbeGen.IntStr(lo, q)
                                             END;
                                             t := SymTab.IntType()
                                           ELSE SemError(230);
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           END; .)
    | "ADR" "(" Design<dt, dk, qd, qn, sfx> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "ADR"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF dt = SymTab.InvalidType THEN
                                             t := SymTab.InvalidType;
                                             QbeGen.CopyOp("0", q)
                                           ELSE
                                              IF sfx
                                                 OR (dk = SymTab.KindVar)
                                                 OR (dk = SymTab.KindParam) THEN
                                                QbeGen.CopyOp("@", q)
                                              ELSE SemError(230);
                                                QbeGen.CopyOp("0", q)
                                              END;
                                             t := SymTab.AddrType()
                                           END; .)
    | "CHR" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "CHR"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF (et # SymTab.InvalidType)
 AND NOT SymTab.IsIntFamily(et) THEN
                                             SemError(211) END;
                                           t := SymTab.CharType(); .)
    | ( "ORD" | "ORDL" ) "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "ORD"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF et # SymTab.InvalidType THEN
                                             IF (SymTab.ClassOf(et) #
                                                 SymTab.ClChar)
 AND (SymTab.ClassOf(et) #
                                                   SymTab.ClBool)
 AND (SymTab.ClassOf(et) #
                                                   SymTab.ClEnum)
 AND NOT SymTab.IsIntFamily(et) THEN
                                               SemError(211) END
                                           END;
                                           t := SymTab.IntType(); .)
    | "CAP" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "CAP"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                         (. QbeGen.CopyOp("@", q);
                                           t := SymTab.CharType(); .)
    | "UCHR" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "UCHR"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. (* UCHR: the UCHAR constructor.
                                              CHAR -> UCHAR (identity);
                                              INTEGER familly -> UCHAR
                                              (codepoint value). *)
                                           IF (et # SymTab.InvalidType)
  AND (SymTab.ClassOf(et) # SymTab.ClChar)
  AND NOT SymTab.IsIntFamily(et) THEN
                                             SemError(211) END;
                                           t := SymTab.UCharType(); .)
    | "CHR8" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "CHR8"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF (et # SymTab.InvalidType)
  AND (SymTab.ClassOf(et) # SymTab.ClUChar) THEN
                                             SemError(211) END;
                                           t := SymTab.CharType(); .)
    | "UORD" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "UORD"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. (* UORD(u): the codepoint as a
                                              32-bit ordinal (INTEGER),
                                              cf. ORD for CHAR. *)
                                           IF (et # SymTab.InvalidType)
  AND (SymTab.ClassOf(et) # SymTab.ClUChar) THEN
                                             SemError(211) END;
                                           t := SymTab.IntType(); .)
    | "ABS" "(" Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "ABS"));
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 1, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF (et # SymTab.InvalidType)
 AND NOT SymTab.IsIntFamily(et)
 AND (SymTab.ClassOf(et) #
                                                SymTab.ClReal) THEN
                                             SemError(211)
                                            ELSE QbeGen.CopyOp("@", q)
                                           END;
                                           t := et; .)
    | "VAL" "(" GetIdent<vn> (. astArg2 := AST.MakeLeaf(AST.NkIdent, vn); .) "," Expr<et, q> ")"
    (. astNode := AST.MakeNode(AST.NkCall);
   AST.SetChild(astNode, 0, AST.MakeLeaf(AST.NkIdent, "VAL"));
   IF astArg2 # AST.NoNode THEN AST.SetChild(astNode, 1, astArg2) END;
   IF astCur # AST.NoNode THEN AST.SetChild(astNode, 2, astCur) END;
   astCur := astNode; astIsLit := TRUE; .)
                                        (. IF NOT SymTab.Lookup(vn) THEN
                                             SemError(201);
                                             t := SymTab.InvalidType
                                           ELSE vt := SymTab.SymType(vn);
                                             IF vt = SymTab.InvalidType THEN
                                               t := SymTab.InvalidType
                                             ELSIF et =
                                                SymTab.InvalidType THEN
                                               t := vt
                                             ELSE
                                               c1 := SymTab.ClassOf(et);
                                               c2 := SymTab.ClassOf(vt);
                                               IF (c1 = SymTab.ClInt)
  AND (c2 = SymTab.ClLong) THEN
                                                 QbeGen.WidenLong(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClLong)
  AND (c2 = SymTab.ClInt) THEN
                                                 QbeGen.NarrowLong(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClInt)
  AND (c2 = SymTab.ClReal) THEN
                                                 QbeGen.ConvIR(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClLong)
  AND (c2 = SymTab.ClReal) THEN
                                                 QbeGen.ConvLR(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClReal)
  AND (c2 = SymTab.ClInt) THEN
                                                 QbeGen.ConvRI(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClReal)
  AND (c2 = SymTab.ClLong) THEN
                                                 QbeGen.ConvRL(q, qa);
                                                 QbeGen.CopyOp(qa, q);
                                                 t := vt
                                               ELSIF ((c1 = SymTab.ClInt)
                                                   OR (c1 =
                                                      SymTab.ClChar)
                                                   OR (c1 =
                                                      SymTab.ClBool)
                                                   OR (c1 =
                                                      SymTab.ClEnum))
 AND ((c2 = SymTab.ClInt)
                                                   OR (c2 =
                                                      SymTab.ClChar)
                                                   OR (c2 =
                                                      SymTab.ClBool)
                                                   OR (c2 =
                                                      SymTab.ClEnum)) THEN
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClPtr)
 AND (c2 = SymTab.ClPtr) THEN
                                                 t := vt
                                               ELSIF (c1 = SymTab.ClReal)
 AND (c2 = SymTab.ClReal) THEN
                                                 t := vt
                                               ELSE SemError(230);
                                                 t := SymTab.InvalidType
                                               END
                                             END
                                           END; .)
    | "(" Expr<et, q> ")"               (. t := et; astIsLit := TRUE; .)
    | SetLit<st, sq>                    (. astIsLit := TRUE; t := st;
                                           QbeGen.CopyOp(sq, q); .)
    | ( "NOT" | "~" ) Fact<t2, q2>      (. astNot := astCur;
                                           IF SymTab.BoolCheck(t2) THEN
                                             t := SymTab.BoolType()
                                           ELSE SemError(212);
                                             t := SymTab.InvalidType END;
                                           IF t # SymTab.InvalidType THEN
                                              QbeGen.CopyOp("@", q)
                                           ELSE QbeGen.CopyOp("0", q)
                                           END;
                                           astIsLit := TRUE;
                                           astCur := AST.MakeUn(
                                             AST.NkUnary, AST.OpNot, astNot); .)
    )
    (. IF NOT astIsLit THEN astCur := AST.NoNode END; .)
           (. IF astCur # AST.NoNode THEN AST.SetTy(astCur, t) END; .) .
  (* Set literals are SET OF [0..255] (8 words); elements validated
     0..255 statically when foldable (222 otherwise), runtime trap
     for computed elements. Ranges always lower via SetRange. *)
  SetLit<VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR astNode: AST.Node; .)
    = "{"                               (. t := SymTab.NewSet(
                                             SymTab.NewSubR(0, 255));
                                           astNode := AST.MakeNode(AST.NkSetLit);
                                           QbeGen.NewSetTemp(8, q);
                                           QbeGen.SetZero(q, 8); .)
      [ SetElem<t, q, astNode> { "," SetElem<t, q, astNode> } ]
      "}"                               (. astCur := astNode; .) .
  (* Typed brace constructor: TypeName{ elems } — BITSET{0} (a set)
     or ArrayName{...} (an array constructor, GNU Modula-2).  The
     declared type sets the width (set) or element type (array). *)
  TypedBraceLit<vt: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR nw: CARDINAL;
                                             astNode, astTail: AST.Node;
                                             savedCls: INTEGER; .)
    = "{"                               (. savedCls := braceCls;
                                           astNode := AST.MakeNode(AST.NkBraceLit);
                                           AST.SetTy(astNode, vt);
                                           astTail := astNode;
                                           IF vt = SymTab.InvalidType THEN
                                             braceCls := -1
                                           ELSE braceCls :=
                                                  SymTab.ClassOf(vt)
                                           END;
                                           IF braceCls = SymTab.ClSet THEN
                                             IF vt = SymTab.InvalidType THEN
                                               nw := 8
                                             ELSE nw := SymTab.SetWords(vt);
                                               IF nw = 0 THEN nw := 8 END
                                             END;
                                             QbeGen.NewSetTemp(nw, q);
                                             QbeGen.SetZero(q, nw)
                                           ELSIF (braceCls =
                                                  SymTab.ClArray)
                                              OR (braceCls =
                                                  SymTab.ClRecord)
                                              OR (braceCls =
                                                  SymTab.ClClass) THEN
                                             QbeGen.CtorBegin(vt)
                                           ELSE
                                             IF vt # SymTab.InvalidType THEN
                                               SemError(230) END;
                                             braceCls := -1
                                           END; .)
      [ BraceElem<vt, q, astNode, astTail>
        { "," BraceElem<vt, q, astNode, astTail> } ]
      "}"                               (. IF (braceCls = SymTab.ClArray)
                                              OR (braceCls =
                                                 SymTab.ClRecord)
                                              OR (braceCls =
                                                 SymTab.ClClass) THEN
                                             QbeGen.CtorEnd(q)
                                           ELSIF braceCls # SymTab.ClSet THEN
                                             QbeGen.CopyOp("0", q)
                                           END;
                                           braceCls := savedCls; .)
                                        (. astCur := astNode; .) .
  BraceElem<vt: SymTab.TypeIndex; VAR sq: QbeGen.QVal;
            VAR node, tail: AST.Node>
                                        (. VAR et, et2: SymTab.TypeIndex;
                                             qe, q2: QbeGen.QVal;
                                             v, v2, reps, k: INTEGER;
                                             elem: SymTab.TypeIndex;
                                             lo: INTEGER;
                                             span: CARDINAL;
                                             cl, cl2: INTEGER;
                                             hasR, hasB: BOOLEAN;
                                             astEl: AST.Node; .)
    =                                   (. hasR := FALSE; hasB := FALSE;
                                           reps := 1; .)
      Expr<et, qe> (. astEl := astCur; .)
      [ ".." Expr<et2, q2>              (. astEl := AST.MakeBin(
                                             AST.NkSubrange, 0, astEl, astCur);
                                           hasR := TRUE; .) ]
      [ "BY" Expr<et2, q2>              (. hasB := TRUE; .) ]
                                        (. IF braceCls = SymTab.ClSet THEN
                                             IF hasB THEN SemError(230) END;
                                             lo := SymTab.SetBaseLo(vt);
                                             span := SymTab.SetCount(vt);
                                             IF (et = SymTab.InvalidType)
                                                OR (hasR AND (et2 =
                                                   SymTab.InvalidType)) THEN
                                             ELSE cl :=
                                                    SymTab.ClassOf(et);
                                               IF hasR THEN
                                                 cl2 :=
                                                   SymTab.ClassOf(et2)
                                               ELSE cl2 := SymTab.ClInt
                                               END;
                                               IF NOT SymTab.SetElemClassOk(cl)
                                                  OR (hasR AND NOT
                                                     SymTab.SetElemClassOk(cl2))
                                               THEN
                                                 SemError(222)
                                               ELSIF hasR
 AND SymTab.ConstInt(qe, v)
 AND SymTab.ConstInt(q2,
                                                     v2)
 AND ((v < lo)
                                                     OR (v2 < lo)
                                                     OR (v >= lo +
                                                        VAL(INTEGER, span))
                                                     OR (v2 >= lo +
                                                        VAL(INTEGER, span))
                                                     OR (v > v2)) THEN
                                                 SemError(222)
                                                ELSIF hasR THEN
                                                  QbeGen.SetRange(sq, qe, q2,
                                                    lo, span)
                                                ELSIF SymTab.ConstInt(qe,
                                                        v)
 AND ((v < lo)
                                                      OR (v >= lo +
                                                         VAL(INTEGER,
                                                           span))) THEN
                                                  SemError(222)
                                                ELSE QbeGen.SetBit(sq, qe,
                                                  lo, span)
                                               END
                                             END
                                           ELSIF (braceCls = SymTab.ClArray)
                                              OR (braceCls =
                                                 SymTab.ClRecord)
                                              OR (braceCls =
                                                 SymTab.ClClass) THEN
                                             IF hasR THEN SemError(230) END;
                                             reps := 1;
                                             IF hasB THEN
                                               IF SymTab.ConstInt(q2, v2)
 AND (v2 >= 1) THEN
                                                 reps := v2
                                               ELSE SemError(230)
                                               END
                                             END;
                                             k := 0;
                                             WHILE k < reps DO
                                               QbeGen.CtorElem(qe);
                                               INC(k)
                                             END
                                           END; .)
                                        (. (* the BY form repeats the
                                             element; keep the AST in
                                             step with CtorElem *)
                                           k := 0;
                                           WHILE k < reps DO
                                             AstAppend(AST.NkBlock,
                                               node, tail, astEl);
                                             INC(k)
                                           END; .) .
  SetElem<st: SymTab.TypeIndex; sq: QbeGen.QVal; node: AST.Node>         (. VAR et, et2: SymTab.TypeIndex;
                                             qe, q2: QbeGen.QVal;
                                             v, v2: INTEGER;
                                             lo: INTEGER;
                                             span: CARDINAL;
                                             cl, cl2: INTEGER;
                                             hasR: BOOLEAN;
                                             astEl: AST.Node; .)
    =                                   (. hasR := FALSE; .)
      Expr<et, qe> (. astEl := astCur; .)
      [ ".." Expr<et2, q2>              (. astEl := AST.MakeBin(
                                             AST.NkSubrange, 0, astEl, astCur);
                                           hasR := TRUE; .) ]
                                        (. lo := SymTab.SetBaseLo(st);
                                           span := SymTab.SetCount(st);
                                           IF (et = SymTab.InvalidType)
                                              OR (hasR AND (et2 =
                                                 SymTab.InvalidType)) THEN
                                           ELSE cl :=
                                                  SymTab.ClassOf(et);
                                             IF hasR THEN
                                               cl2 :=
                                                 SymTab.ClassOf(et2)
                                             ELSE cl2 := SymTab.ClInt
                                             END;
                                             IF NOT SymTab.SetElemClassOk(cl)
                                                OR (hasR AND NOT
                                                   SymTab.SetElemClassOk(cl2))
                                             THEN
                                               SemError(222)
                                             ELSIF hasR
 AND SymTab.ConstInt(qe, v)
 AND SymTab.ConstInt(q2,
                                                   v2)
 AND ((v < lo)
                                                   OR (v2 < lo)
                                                   OR (v >= lo +
                                                      VAL(INTEGER, span))
                                                   OR (v2 >= lo +
                                                      VAL(INTEGER, span))
                                                   OR (v > v2)) THEN
                                               SemError(222)
                                              ELSIF hasR THEN
                                                QbeGen.SetRange(sq, qe, q2,
                                                  lo, span)
                                              ELSIF SymTab.ConstInt(qe,
                                                      v)
 AND ((v < lo)
                                                    OR (v >= lo +
                                                       VAL(INTEGER,
                                                         span))) THEN
                                                SemError(222)
                                              ELSE QbeGen.SetBit(sq, qe,
                                                lo, span)
                                             END
                                           END; .)
                                        (. AST.SetChild(node,
                                             AST.NChild(node), astEl); .) .
  GetIdent<VAR n: SymTab.Name>
    = ident                             (. LexName(n); .) .

END M2.