CocoR/Test2/SimpleQ.atg

COMPILER SimpleQ
(* Simplified Modula-2 without PROCEDURE / FUNCTION, with a QBE backend
   for the scalar subset (see QbeGen for details).

   - program module only, no DEFINITION / IMPLEMENTATION split
   - no local modules, no EXPORT, no PRIORITY
   - no ProcedureDeclaration, FormalParameters, ProcedureType,
     ProcedureCall, ActualParameters, FORWARD, RETURN
   - statements: assignment, IF, CASE, WHILE, REPEAT, LOOP/EXIT, FOR, WITH
   - symbol table (SymTab) with static type checking: same error codes
     200/201/202 and 210-224 as SimpleMod2 (Test1), same lenient rules
     (single pass, declare-before-use; INTEGER, CARDINAL and subranges
     form one integer family; no mixed INTEGER/REAL arithmetic; INTEGER
     assigns to REAL; 1-character literal is CHAR; InvalidType suppresses
     follow-on errors)
   - backend (QbeGen): emits QBE SSA to gen_qbe/<ModName>.ssa
     (directory gen_qbe/ must exist), assembled with "qbe" and linked
     with "cc" into a native binary. Only scalar data is lowered:
     INTEGER/CARDINAL/SHORTINT/LONGINT/BOOLEAN/CHAR/enumerations as
     QBE "w", REAL/LONGREAL as QBE "d". Everything else parses and
     type-checks but gets error 230 (qbe backend: construct not
     supported in scalar subset): ARRAY/RECORD/SET/POINTER variables,
     string variables, WITH, IN, set literals, non-literal CONST
     expressions and BY steps, EXIT outside LOOP, imported names used
     as values.
   - test convention (the language has no I/O): a global
       VAR ExitCode : INTEGER;
     makes the generated main return its value as the process exit
     code; otherwise the program returns 0. *)

IMPORT SymTab, QbeGen;

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

IGNORE CHR(9) .. CHR(13)

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

TOKENS
  ident   = letter { letter | digit } .
  integer = digit { digit }
          | digit { digit } CONTEXT("..")
          | digit { hexDigit } "H" .
  real    = digit { digit } "." { digit }
            [ "E" [ "+" | "-" ] digit { digit } ] .
  string  = "'" { noQuote1 } "'"
          | '"' { noQuote2 } '"' .

PRODUCTIONS
  SimpleQ                               (. VAR m1, m2: SymTab.Name; .)
    = "MODULE"
      GetIdent<m1>                      (. SymTab.Init; QbeGen.OpenModule(m1);
                                           IF ~SymTab.Enter(m1, SymTab.KindModule)
                                           THEN SemError(200) END .)
      ";"
      { Import } Block GetIdent<m2>     (. IF ~SymTab.Equal(m1, m2)
                                           THEN SemError(202) END .)
      "."                               (. QbeGen.EndModule;
                                           SymTab.PrintTable; .) .
  Import                                (. VAR n: SymTab.Name; .)
    = "FROM"
      GetIdent<n>                       (. IF ~SymTab.Enter(n, SymTab.KindImport)
                                           THEN SemError(200) END .)
      "IMPORT"
      ImportList ";"
    | "IMPORT"
      ImportList ";" .
  ImportList                            (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF ~SymTab.Enter(n, SymTab.KindImport)
                                           THEN SemError(200) END .)
      { ","
        GetIdent<n>                     (. IF ~SymTab.Enter(n, SymTab.KindImport)
                                           THEN SemError(200) END .) } .
  Block      = { Declaration }
               [ "BEGIN"                (. QbeGen.BeginBody; .)
                 StatSeq ]
               "END" .
  Declaration = "CONST"
                          {
                            ConstDecl ";" }
              | "TYPE"
                          {
                            TypeDecl ";" }
              | "VAR"
                          {
                            VarDecl ";" } .
  ConstDecl                             (. VAR n: SymTab.Name;
                                             t: SymTab.TypeIndex;
                                             qv: QbeGen.QVal;
                                             cls: INTEGER; .)
    = GetIdent<n>                       (. IF ~SymTab.Enter(n, SymTab.KindConst)
                                           THEN SemError(200) END .)
      "="
      ConstExpr<t, qv>                  (. SymTab.SetSymType(n, t);
                                           cls := SymTab.ClassOf(t);
                                           IF cls = SymTab.ClStr THEN
                                             SemError(230)
                                           ELSIF ~QbeGen.IsImm(qv) THEN
                                             SemError(230)
                                           END;
                                           QbeGen.DeclConst(n, qv, t); .) .
  ConstExpr <VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
    = Expr<t, q> .
  TypeDecl                              (. VAR n: SymTab.Name;
                                             t0, t1: SymTab.TypeIndex; .)
    = GetIdent<n>                       (. IF ~SymTab.Enter(n, SymTab.KindType)
                                           THEN SemError(200) END;
                                           t0 := SymTab.NewAlias();
                                           SymTab.SetSymType(n, t0); .)
      "="
      Type<t1>                          (. IF t1 = t0 THEN SemError(223);
                                             SymTab.SetTarget(t0,
                                               SymTab.InvalidType)
                                           ELSE SymTab.SetTarget(t0, t1) END; .) .
  VarDecl                               (. VAR t: SymTab.TypeIndex;
                                             i: CARDINAL;
                                             nm: SymTab.Name;
                                             cls: INTEGER; .)
    = VarIdents ":"
      Type<t>                           (. cls := SymTab.ClassOf(t);
                                           IF (cls # SymTab.ClInt)
                                              & (cls # SymTab.ClReal)
                                              & (cls # SymTab.ClBool)
                                              & (cls # SymTab.ClChar)
                                              & (cls # SymTab.ClEnum) THEN
                                             SemError(230)
                                           END;
                                           i := 0;
                                           WHILE i < SymTab.PendCount() DO
                                             SymTab.PendName(i, nm);
                                             QbeGen.DeclVar(nm, t);
                                             INC(i)
                                           END;
                                           SymTab.FixPending(t); .) .
  VarIdents                             (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF ~SymTab.EnterPending(n,
                                             SymTab.KindVar)
                                           THEN SemError(200) END .)
      { ","
        GetIdent<n>                     (. IF ~SymTab.EnterPending(n,
                                             SymTab.KindVar)
                                           THEN SemError(200) END .) } .
  QualIdent <VAR t: SymTab.TypeIndex>
                                        (. VAR n, m: SymTab.Name; .)
    = GetIdent<n>                       (. IF ~SymTab.Lookup(n) THEN
                                             SemError(201);
                                             t := SymTab.InvalidType
                                           ELSIF (SymTab.SymKind(n) #
                                                  SymTab.KindType)
                                             & (SymTab.SymKind(n) #
                                                SymTab.KindPredef)
                                             & (SymTab.SymKind(n) #
                                                SymTab.KindImport) THEN
                                             SemError(221);
                                             t := SymTab.InvalidType
                                           ELSE t := SymTab.SymType(n) END; .)
      { "."
        GetIdent<m>                     (. t := SymTab.InvalidType; .) } .

  (* Types: ProcedureType removed; subrange factored for LL(1) *)
  Type <VAR t: SymTab.TypeIndex>
    = SimpleType<t> | ArrayType<t> | RecordType<t>
    | SetType<t> | PointerType<t> .
  SimpleType <VAR t: SymTab.TypeIndex>
                                        (. VAR t1, t2: SymTab.TypeIndex;
                                             q1, q2: QbeGen.QVal; .)
    = QualIdent<t> [ "["
                      ConstExpr<t1, q1>  (. IF (t1 # SymTab.InvalidType)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .)
                      ".."
                      ConstExpr<t2, q2>  (. IF (t2 # SymTab.InvalidType)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .)
                      "]"
                                     (. t := SymTab.NewSub(t1); .) ]
    | "["
      ConstExpr<t1, q1>                  (. IF (t1 # SymTab.InvalidType)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(t1) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .)
      ".."
      ConstExpr<t2, q2>                  (. IF (t2 # SymTab.InvalidType)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(t2) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .)
      "]"                                (. t := SymTab.NewSub(t1); .)
    | Enum<t> .
  Enum <VAR t: SymTab.TypeIndex>
                                        (. VAR n: SymTab.Name;
                                             qs: QbeGen.QVal;
                                             ord: INTEGER; .)
    = "("                               (. t := SymTab.NewEnum();
                                           ord := 0; .)
      GetIdent<n>                       (. IF ~SymTab.Enter(n,
                                             SymTab.KindConst)
                                           THEN SemError(200) END;
                                           SymTab.SetSymType(n, t);
                                           QbeGen.IntStr(ord, qs);
                                           QbeGen.DeclConst(n, qs, t);
                                           INC(ord); .)
      { ","
        GetIdent<n>                     (. IF ~SymTab.Enter(n,
                                             SymTab.KindConst)
                                           THEN SemError(200) END;
                                           SymTab.SetSymType(n, t);
                                           QbeGen.IntStr(ord, qs);
                                           QbeGen.DeclConst(n, qs, t);
                                           INC(ord); .) }
      ")" .
  ArrayType <VAR t: SymTab.TypeIndex>
                                        (. VAR s, s2, e: SymTab.TypeIndex;
                                             qs: QbeGen.QVal; .)
    = "ARRAY"
      SimpleType<s>                     (. IF (s # SymTab.InvalidType)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .)
      { ","
        SimpleType<s2>                  (. IF (s2 # SymTab.InvalidType)
                                            & (SymTab.ClassOf(s2) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(s2) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(s2) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END; .) }
      "OF"
      Type<e>                           (. t := SymTab.NewArray(e); .) .
  RecordType <VAR t: SymTab.TypeIndex>
    = "RECORD"                          (. t := SymTab.NewRecord(); .)
      FieldSeq<t>
      "END" .
  FieldSeq <rt: SymTab.TypeIndex>
    = Field<rt> { ";"
                  Field<rt> } .
  Field <rt: SymTab.TypeIndex>
                                        (. VAR et: SymTab.TypeIndex; .)
    = [ FieldIdents<rt> ":"
        Type<et>                       (. SymTab.FixPendingF(rt, et); .) ] .
  FieldIdents <rt: SymTab.TypeIndex>
                                        (. VAR n: SymTab.Name; .)
    = GetIdent<n>                       (. IF ~SymTab.FieldPending(rt, n)
                                           THEN SemError(200) END .)
      { ","
        GetIdent<n>                     (. IF ~SymTab.FieldPending(rt, n)
                                           THEN SemError(200) END .) } .
  SetType <VAR t: SymTab.TypeIndex>
                                        (. VAR s: SymTab.TypeIndex; .)
    = "SET"
      "OF"
      SimpleType<s>                     (. IF (s # SymTab.InvalidType)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClInt)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClChar)
                                            & (SymTab.ClassOf(s) #
                                               SymTab.ClEnum) THEN
                                            SemError(224) END;
                                           t := SymTab.NewSet(s); .) .
  PointerType <VAR t: SymTab.TypeIndex>
                                        (. VAR b: SymTab.TypeIndex; .)
    = "POINTER"
      "TO"
      Type<b>                           (. t := SymTab.NewPtr(b); .) .

  (* Statements: ProcedureCall and RETURN removed *)
  StatSeq    = Stat { ";"
                     Stat } .
  Stat                                  (. VAR lx: QbeGen.QVal; .)
    = [ Assign | IfStat | CaseStat | WhileStat
      | RepeatStat | LoopStat | ForStat | WithStat
      | "EXIT"                 (. IF QbeGen.TopLoop(lx) THEN
                                    QbeGen.Jmp(lx)
                                  ELSE SemError(230) END; .) ] .
  Assign                                (. VAR dt, et: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, qe, qt: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx: BOOLEAN;
                                             isR, conv: BOOLEAN; .)
    = Design<dt, dk, qd, qn, sfx> ":="
      Expr<et, qe>                      (. IF (dt # SymTab.InvalidType)
                                           & (dk # SymTab.KindVar)
                                           & (dk # SymTab.KindField)
                                           & (dk # SymTab.KindImport) THEN
                                           SemError(210)
                                         ELSIF ~SymTab.Assignable(et, dt) THEN
                                           SemError(210) END;
                                         IF dk = SymTab.KindImport THEN
                                           SemError(230)
                                         END;
                                         isR := (dt # SymTab.InvalidType)
                                                & (SymTab.ClassOf(dt)
                                                   = SymTab.ClReal);
                                         conv := isR
                                                 & SymTab.IsIntFamily(et);
                                         IF ~sfx
                                            & (dk = SymTab.KindVar) THEN
                                           IF conv THEN
                                             QbeGen.ConvIR(qe, qt);
                                             QbeGen.StoreVar(qn, qt, TRUE)
                                           ELSE
                                             QbeGen.StoreVar(qn, qe, isR)
                                           END
                                         END; .) .
  IfStat                                (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             lThen, lElse, lEnd: QbeGen.QVal;
                                             hasElse: BOOLEAN; .)
    = "IF"
      Expr<t, q>                        (. IF ~SymTab.BoolCheck(t) THEN
                                           SemError(214) END;
                                           QbeGen.NewLabel(lThen);
                                           QbeGen.NewLabel(lElse);
                                           QbeGen.NewLabel(lEnd);
                                           QbeGen.Jnz(q, lThen, lElse);
                                           QbeGen.EmitLabel(lThen);
                                           hasElse := FALSE; .)
      "THEN"
      StatSeq
      { "ELSIF"                         (. QbeGen.Jmp(lEnd);
                                           QbeGen.EmitLabel(lElse); .)
        Expr<t, q>                      (. IF ~SymTab.BoolCheck(t) THEN
                                           SemError(214) END;
                                           QbeGen.NewLabel(lThen);
                                           QbeGen.NewLabel(lElse);
                                           QbeGen.Jnz(q, lThen, lElse);
                                           QbeGen.EmitLabel(lThen); .)
        "THEN"
        StatSeq }
      [ "ELSE"                          (. QbeGen.Jmp(lEnd);
                                           QbeGen.EmitLabel(lElse);
                                           hasElse := TRUE; .)
        StatSeq ]
      "END"                             (. IF ~hasElse THEN
                                           QbeGen.EmitLabel(lElse)
                                         END;
                                         QbeGen.EmitLabel(lEnd); .) .
  CaseStat                              (. VAR st: SymTab.TypeIndex;
                                             sq: QbeGen.QVal;
                                             lEnd: QbeGen.QVal; .)
    = "CASE"
      Expr<st, sq>
      "OF"                              (. QbeGen.NewLabel(lEnd); .)
      Case<st, sq, lEnd> { "|"
                 Case<st, sq, lEnd> }
      [ "ELSE"
        StatSeq ]
      "END"                             (. QbeGen.EmitLabel(lEnd); .) .
  Case <sel: SymTab.TypeIndex; sq: QbeGen.QVal; endL: QbeGen.QVal>
                                        (. VAR lB, lN: QbeGen.QVal; .)
    = [ LabelList<sel, sq, lB, lN> ":" (. QbeGen.EmitLabel(lB); .)
        StatSeq                         (. QbeGen.Jmp(endL);
                                           QbeGen.EmitLabel(lN); .) ] .
  LabelList <sel: SymTab.TypeIndex; sq: QbeGen.QVal;
             VAR lB: QbeGen.QVal; VAR lN: QbeGen.QVal>
    =                                   (. QbeGen.NewLabel(lB);
                                           QbeGen.NewLabel(lN); .)
      Labels<sel, sq, lB> { ","
                    Labels<sel, sq, lB> }
                                        (. QbeGen.Jmp(lN); .) .
  Labels <sel: SymTab.TypeIndex; sq: QbeGen.QVal; lB: QbeGen.QVal>
                                        (. VAR t, t2: SymTab.TypeIndex;
                                             q, q2, qk, qg, ql, qb: QbeGen.QVal;
                                             lC: QbeGen.QVal;
                                             r, hasRange: BOOLEAN; .)
    = ConstExpr<t, q>                   (. IF ~SymTab.EqCheck(t, sel) THEN
                                           SemError(213) END;
                                           r := (SymTab.ClassOf(sel)
                                                 = SymTab.ClReal)
                                                & (SymTab.ClassOf(t)
                                                   = SymTab.ClReal);
                                           hasRange := FALSE; .)
      [ ".."
        ConstExpr<t2, q2>               (. IF ~SymTab.EqCheck(t2, sel) THEN
                                           SemError(213) END;
                                           hasRange := TRUE; .) ]
                                        (. IF hasRange THEN
                                             QbeGen.Cmp(SymTab.OpGe,
                                               sq, q, qg, r);
                                             QbeGen.Cmp(SymTab.OpLe,
                                               sq, q2, ql, r);
                                             QbeGen.NewTemp(qb);
                                             QbeGen.Op3("and", qb, qg, ql,
                                               FALSE)
                                           ELSE
                                             QbeGen.Cmp(SymTab.OpEq,
                                               sq, q, qb, r)
                                           END;
                                           QbeGen.NewLabel(lC);
                                           QbeGen.Jnz(qb, lB, lC);
                                           QbeGen.EmitLabel(lC); .) .
  WhileStat                             (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             lC, lB, lE: QbeGen.QVal; .)
    = "WHILE"                           (. QbeGen.NewLabel(lC);
                                           QbeGen.NewLabel(lB);
                                           QbeGen.NewLabel(lE);
                                           QbeGen.EmitLabel(lC); .)
      Expr<t, q>                        (. IF ~SymTab.BoolCheck(t) THEN
                                           SemError(214) END;
                                           QbeGen.Jnz(q, lB, lE);
                                           QbeGen.EmitLabel(lB); .)
      "DO"
      StatSeq
      "END"                             (. QbeGen.Jmp(lC);
                                           QbeGen.EmitLabel(lE); .) .
  RepeatStat                            (. VAR t: SymTab.TypeIndex;
                                             q: QbeGen.QVal;
                                             lTop, lE: QbeGen.QVal; .)
    = "REPEAT"                          (. QbeGen.NewLabel(lTop);
                                           QbeGen.NewLabel(lE);
                                           QbeGen.EmitLabel(lTop); .)
      StatSeq
      "UNTIL"
      Expr<t, q>                        (. IF ~SymTab.BoolCheck(t) THEN
                                           SemError(214) END;
                                           QbeGen.Jnz(q, lE, lTop);
                                           QbeGen.EmitLabel(lE); .) .
  LoopStat                              (. VAR lTop, lE: QbeGen.QVal; .)
    = "LOOP"                            (. QbeGen.NewLabel(lTop);
                                           QbeGen.NewLabel(lE);
                                           QbeGen.EmitLabel(lTop);
                                           QbeGen.PushLoop(lE); .)
      StatSeq
      "END"                             (. QbeGen.Jmp(lTop);
                                           QbeGen.EmitLabel(lE);
                                           QbeGen.PopLoop; .) .
  ForStat                               (. VAR n, lv: SymTab.Name;
                                             lo, hi, by: SymTab.TypeIndex;
                                             qlo, qhi, qby, hiS, byS: QbeGen.QVal;
                                             qt, qk: QbeGen.QVal;
                                             lTop, lChk, lEnd: QbeGen.QVal;
                                             neg: BOOLEAN; .)
    = "FOR"
      GetIdent<n>                       (. IF ~SymTab.Lookup(n) THEN
                                            SemError(201)
                                          ELSIF (SymTab.SymKind(n) #
                                                 SymTab.KindVar)
                                            & (SymTab.SymKind(n) #
                                               SymTab.KindField) THEN
                                            SemError(220)
                                          ELSIF (SymTab.SymType(n) #
                                                 SymTab.InvalidType)
                                            & ~SymTab.IsIntFamily(
                                                SymTab.SymType(n)) THEN
                                            SemError(220) END;
                                            QbeGen.CopyOp(n, lv); .)
      ":="
      Expr<lo, qlo>                     (. IF (lo # SymTab.InvalidType)
                                           & ~SymTab.IsIntFamily(lo) THEN
                                           SemError(220) END;
                                           IF (lo # SymTab.InvalidType)
                                              & SymTab.IsIntFamily(lo) THEN
                                             QbeGen.StoreVar(lv, qlo, FALSE)
                                           ELSE
                                             QbeGen.StoreVar(lv, "0", FALSE)
                                           END; .)
      "TO"
      Expr<hi, qhi>                     (. IF (hi # SymTab.InvalidType)
                                           & ~SymTab.IsIntFamily(hi) THEN
                                           SemError(220) END;
                                           QbeGen.CopyOp(qhi, hiS);
                                           QbeGen.CopyOp("1", byS);
                                           neg := FALSE;
                                           by := SymTab.IntType(); .)
      [ "BY"
        ConstExpr<by, qby>              (. IF (by # SymTab.InvalidType)
                                           & ~SymTab.IsIntFamily(by) THEN
                                           SemError(220) END;
                                           IF QbeGen.IsImm(qby) THEN
                                             QbeGen.CopyOp(qby, byS);
                                             neg := QbeGen.IsNeg(qby)
                                           ELSE SemError(230);
                                             QbeGen.CopyOp("1", byS);
                                             neg := FALSE
                                           END; .) ]
      "DO"                              (. QbeGen.NewLabel(lTop);
                                           QbeGen.NewLabel(lChk);
                                           QbeGen.NewLabel(lEnd);
                                           QbeGen.Jmp(lChk);
                                           QbeGen.EmitLabel(lTop); .)
      StatSeq
      "END"                             (. QbeGen.LoadVar(lv, FALSE, qt);
                                           QbeGen.NewTemp(qk);
                                           QbeGen.Op3("add", qk, qt, byS,
                                             FALSE);
                                           QbeGen.StoreVar(lv, qk, FALSE);
                                           QbeGen.EmitLabel(lChk);
                                           QbeGen.LoadVar(lv, FALSE, qt);
                                           QbeGen.NewTemp(qk);
                                           IF neg THEN
                                             QbeGen.Op3("csgew", qk, qt, hiS,
                                               FALSE)
                                           ELSE
                                             QbeGen.Op3("cslew", qk, qt, hiS,
                                               FALSE)
                                           END;
                                           QbeGen.Jnz(qk, lTop, lEnd);
                                           QbeGen.EmitLabel(lEnd); .) .
  WithStat                              (. VAR dt: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             dq: QbeGen.QVal;
                                             qn: SymTab.Name;
                                             sfx: BOOLEAN;
                                             pushed: BOOLEAN; .)
    = "WITH"
      Design<dt, dk, dq, qn, sfx>       (. pushed := FALSE;
                                           IF dt # SymTab.InvalidType THEN
                                             pushed :=
                                               SymTab.PushRecord(dt);
                                             IF ~pushed THEN
                                               SemError(215)
                                             END
                                           END;
                                           IF pushed THEN
                                             QbeGen.NoQbeEnter;
                                             SemError(230)
                                           END; .)
      "DO"
      StatSeq
      "END"                             (. IF pushed THEN
                                             SymTab.PopScope;
                                             QbeGen.NoQbeExit
                                           END; .) .

  (* Expressions: Designator without ActualParameters.
     Only record fields resolve qualified access; WITH pushes an
     inner scope so field names also work unqualified in its body
     (both report 230 in the scalar subset). Each expression
     synthesizes its SymTab type in t and its QBE operand in q
     (an immediate or a fresh %temporary holding the value). *)
  Design <VAR t: SymTab.TypeIndex; VAR k: INTEGER;
          VAR q: QbeGen.QVal; VAR qn: SymTab.Name; VAR sfx: BOOLEAN>
                                        (. VAR n, m: SymTab.Name;
                                             it: SymTab.TypeIndex;
                                             qr: QbeGen.QVal;
                                             cls: INTEGER; .)
    = GetIdent<n>                       (. QbeGen.CopyOp(n, qn);
                                           sfx := FALSE;
                                           IF ~SymTab.Lookup(n) THEN
                                             SemError(201);
                                             t := SymTab.InvalidType; k := -1;
                                             QbeGen.CopyOp("0", q)
                                           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)
                                               ELSE
                                                 cls :=
                                                   SymTab.ClassOf(t);
                                                 IF (t #
                                                     SymTab.InvalidType)
                                                    & (cls # SymTab.ClStr)
                                                    & ((cls = SymTab.ClInt)
                                                    OR (cls = SymTab.ClReal)
                                                    OR (cls = SymTab.ClBool)
                                                    OR (cls = SymTab.ClChar)
                                                    OR (cls
                                                        = SymTab.ClEnum)) THEN
                                                   QbeGen.LoadVar(n,
                                                     cls = SymTab.ClReal, q)
                                                 ELSE
                                                   QbeGen.CopyOp("0", q)
                                                 END
                                               END
                                             ELSIF k = SymTab.KindVar THEN
                                               cls := SymTab.ClassOf(t);
                                               IF (cls = SymTab.ClInt)
                                                  OR (cls = SymTab.ClReal)
                                                  OR (cls = SymTab.ClBool)
                                                  OR (cls = SymTab.ClChar)
                                                  OR (cls
                                                      = SymTab.ClEnum) THEN
                                                 QbeGen.LoadVar(n,
                                                   cls = SymTab.ClReal, q)
                                               ELSE SemError(230);
                                                 QbeGen.CopyOp("0", q)
                                               END
                                             ELSE QbeGen.CopyOp("0", q);
                                               IF k = SymTab.KindField THEN
                                                 IF ~QbeGen.NoQbe() THEN
                                                   SemError(230)
                                                 END
                                               ELSIF k
                                                     = SymTab.KindImport THEN
                                                 SemError(230)
                                               END
                                             END
                                           END; .)
      { "."                             (. sfx := TRUE; .)
        GetIdent<m>                     (. IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClRecord THEN
                                             SemError(215);
                                             t := SymTab.InvalidType
                                           ELSIF ~SymTab.FieldExists(t, m) THEN
                                             SemError(216);
                                             t := SymTab.InvalidType
                                           ELSE t := SymTab.FieldType(t, m);
                                             SemError(230)
                                           END;
                                           QbeGen.CopyOp("0", q); .)
      | "["                             (. sfx := TRUE; .)
        Expr<it, qr>                    (. IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClArray THEN
                                             SemError(217);
                                             t := SymTab.InvalidType
                                           ELSIF (it #
                                                  SymTab.InvalidType)
                                             & ~SymTab.IsIntFamily(it) THEN
                                             SemError(218);
                                             t := SymTab.InvalidType
                                           ELSE t :=
                                             SymTab.ArrayElem(t);
                                             SemError(230)
                                           END;
                                           QbeGen.CopyOp("0", q); .)
        { ","
          Expr<it, qr>                  (. IF (it # SymTab.InvalidType)
                                           & ~SymTab.IsIntFamily(it) THEN
                                           SemError(218) END; .) }
        "]"
      | "^"                             (. sfx := TRUE;
                                           IF t = SymTab.InvalidType THEN
                                           ELSIF SymTab.ClassOf(t) #
                                                 SymTab.ClPtr THEN
                                             SemError(219);
                                             t := SymTab.InvalidType
                                           ELSE t := SymTab.PtrBase(t);
                                             SemError(230)
                                           END;
                                           QbeGen.CopyOp("0", q); .) } .
  Expr <VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR t2: SymTab.TypeIndex;
                                             tc, op: INTEGER;
                                             q2, qk: QbeGen.QVal;
                                             r: BOOLEAN; .)
    = SimExpr<t, q> [ Rel<op> SimExpr<t2, q2>
      (. IF op = SymTab.OpIn THEN
           IF SymTab.InCheck(t, t2) THEN
             t := SymTab.BoolType();
             SemError(230)
           ELSE SemError(222);
             t := SymTab.InvalidType
           END;
           QbeGen.CopyOp("0", q)
         ELSE
           tc := SymTab.ClassOf(t);
           IF SymTab.RelCheck(t, t2, op) THEN
             t := SymTab.BoolType()
           ELSE SemError(213); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             r := tc = SymTab.ClReal;
             QbeGen.Cmp(op, q, q2, qk, r);
             QbeGen.CopyOp(qk, q)
           ELSE QbeGen.CopyOp("0", q)
           END
         END; .) ] .
  Rel <VAR op: INTEGER>
    = "="                     (. op := SymTab.OpEq; .)
    | "#"                     (. op := SymTab.OpNeq1; .)
    | "<>"                    (. op := SymTab.OpNeq2; .)
    | "<"                     (. 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: SymTab.TypeIndex;
                                             op: INTEGER;
                                             q2, qt: QbeGen.QVal;
                                             neg, isR: BOOLEAN; .)
    =                                   (. neg := FALSE; .)
      [ "+" | "-"                       (. neg := TRUE; .) ]
      Term<t, q>                        (. IF neg THEN
                                           IF QbeGen.IsImm(q) THEN
                                             QbeGen.NegFold(q, q)
                                           ELSE QbeGen.NewTemp(qt);
                                             QbeGen.NegQ(q, qt,
                                               SymTab.ClassOf(t)
                                               = SymTab.ClReal);
                                             QbeGen.CopyOp(qt, q)
                                           END
                                         END; .)
      { AddOp<op> Term<t2, q2>
      (. IF op = SymTab.OpOr THEN
           IF SymTab.BoolCheck(t) & SymTab.BoolCheck(t2) THEN
             t := SymTab.BoolType()
           ELSE SemError(212); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             QbeGen.NewTemp(qt);
             QbeGen.Op3("or", qt, q, q2, FALSE);
             QbeGen.CopyOp(qt, q)
           ELSE QbeGen.CopyOp("0", q)
           END
         ELSE
           IF SymTab.ArithCheck(t, t2, FALSE, res2) THEN t := res2
           ELSE SemError(211); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             isR := SymTab.ClassOf(t) = SymTab.ClReal;
             QbeGen.NewTemp(qt);
             IF op = SymTab.OpAdd THEN
               QbeGen.Op3("add", qt, q, q2, isR)
             ELSE
               QbeGen.Op3("sub", qt, q, q2, isR)
             END;
             QbeGen.CopyOp(qt, q)
           ELSE QbeGen.CopyOp("0", q)
           END
         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: SymTab.TypeIndex;
                                             op: INTEGER;
                                             q2, qt: QbeGen.QVal;
                                             isR: BOOLEAN; .)
    = Fact<t, q> { MulOp<op> Fact<t2, q2>
      (. IF op = SymTab.OpAnd THEN
           IF SymTab.BoolCheck(t) & SymTab.BoolCheck(t2) THEN
             t := SymTab.BoolType()
           ELSE SemError(212); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             QbeGen.NewTemp(qt);
             QbeGen.Op3("and", qt, q, q2, FALSE);
             QbeGen.CopyOp(qt, q)
           ELSE QbeGen.CopyOp("0", q)
           END
         ELSE
           IF SymTab.ArithCheck(t, t2,
                (op = SymTab.OpDiv) OR (op = SymTab.OpMod),
                res2) THEN t := res2
           ELSE SemError(211); t := SymTab.InvalidType END;
           IF t # SymTab.InvalidType THEN
             isR := SymTab.ClassOf(t) = SymTab.ClReal;
             QbeGen.NewTemp(qt);
             IF op = SymTab.OpTimes THEN
               QbeGen.Op3("mul", qt, q, q2, isR)
             ELSIF op = SymTab.OpSlash THEN
               QbeGen.Op3("div", qt, q, q2, isR)
             ELSIF op = SymTab.OpDiv THEN
               QbeGen.Op3("div", qt, q, q2, FALSE)
             ELSE
               QbeGen.Op3("rem", qt, q, q2, FALSE)
             END;
             QbeGen.CopyOp(qt, q)
           ELSE QbeGen.CopyOp("0", q)
           END
         END; .) } .
  MulOp <VAR op: INTEGER>
    = "*"                     (. op := SymTab.OpTimes; .)
    | "/"                     (. op := SymTab.OpSlash; .)
    | "DIV"                   (. op := SymTab.OpDiv; .)
    | "MOD"                   (. op := SymTab.OpMod; .)
    | "AND"                   (. op := SymTab.OpAnd; .)
    | "&"                     (. op := SymTab.OpAnd; .) .
  Fact <VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR s: ARRAY [0 .. 255] OF CHAR;
                                             t2, et, dt, st: SymTab.TypeIndex;
                                             dk: INTEGER;
                                             qd, q2: QbeGen.QVal;
                                             qnF: SymTab.Name;
                                             sfxF: BOOLEAN; .)
    = integer                         (. LexString(s);
                                         QbeGen.NormInt(s, q);
                                         t := SymTab.IntType(); .)
    | real                            (. LexString(s);
                                         QbeGen.NormReal(s, q);
                                         t := SymTab.RealType(); .)
    | string                          (. LexString(s);
                                         IF SymTab.StrLen(s) <= 3 THEN
                                           t := SymTab.CharType();
                                           QbeGen.IntStr(
                                             QbeGen.CharVal(s), q)
                                         ELSE t := SymTab.NewStr();
                                           SemError(230);
                                           QbeGen.CopyOp("0", q)
                                         END; .)
    | Design<dt, dk, qd, qnF, sfxF>    (. t := dt;
                                         QbeGen.CopyOp(qd, q); .)
    | "("
      Expr<et, q> ")"                 (. t := et; .)
    | ( "NOT" | "~" )
      Fact<t2, q2>                    (. IF SymTab.BoolCheck(t2) THEN
                                           t := SymTab.BoolType()
                                         ELSE SemError(212);
                                           t := SymTab.InvalidType END;
                                         IF t # SymTab.InvalidType THEN
                                           QbeGen.NotQ(q2, q)
                                         ELSE QbeGen.CopyOp("0", q)
                                         END; .)
    | SetLit<st>                      (. t := st;
                                         SemError(230);
                                         QbeGen.CopyOp("0", q); .) .
  SetLit <VAR t: SymTab.TypeIndex>
                                        (. VAR first, et: SymTab.TypeIndex;
                                             qe: QbeGen.QVal; .)
    = "{"
                                (. t := SymTab.SetFor(SymTab.IntType()); .)
      [ Elem<et, qe>            (. first := et; t := SymTab.SetFor(et); .)
        { ","
          Elem<et, qe>          (. IF ~SymTab.SetElemCheck(first, et) THEN
                                SemError(222) END; .) } ]
      "}" .
  Elem <VAR t: SymTab.TypeIndex; VAR q: QbeGen.QVal>
                                        (. VAR t2: SymTab.TypeIndex;
                                             q2: QbeGen.QVal; .)
    = Expr<t, q> [ ".."
                Expr<t2, q2>    (. IF ~SymTab.SetElemCheck(t, t2) THEN
                                SemError(222) END; .) ] .

  GetIdent <VAR n: SymTab.Name>
    = ident                           (. LexName(n); .) .

END SimpleQ.