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+# Lower phase — L7 complete (2026-10-08)
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+
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+Branch **`ast-stage-c`**. Tag **`v3-lower7-complete`**.
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+
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+This closes L7: **`Lower` is the only emitter**, the inline emit that
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+could be removed cleanly is gone, the `-lower` scaffold is retired, and
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+dead code is swept. Verified with `compiler/run_tests.sh`
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+(**181/181**) and `bootstrap/fixpoint.sh` (**FIXPOINT OK**) after every
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+step.
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+
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+## What happened, in order
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+
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+### 1. The switch is flipped (`857c221`)
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+
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+The driver (`compiler/src/compiler.frm`) always runs the per-unit
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+`Lower` emit (`BeginSession`/`BeginUnit`/`LowerUnitNow`/`EndSession`);
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+the grammar's inline emit runs suppressed (`SetNoEmit`) and is
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+discarded. A no-op flip, because `Lower` had been verified
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+byte-identical to the legacy inline emit on every single-file test and
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+every session.
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+
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+### 2. Inline emit deleted from statements and declarations
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+
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+`e5830b2` (builtin statements), `ce37247` (control flow), `acc4e91`
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+(declarations/lifecycle). Not mechanical: `TopLoop`/`PushLoop`/
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+`TopWith`/`PushWith`/`IsImm`/`Fold2`/`LocFull`/`ConstInt` are checks or
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+parser state and stay.
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+
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+### 3. A real bug found and fixed (`7de78bb`)
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+
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+Removing the grammar's `QbeGen.DeclVar` exposed a latent mis-resolution
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+(`Strings.Replace`'s `src` VAR actual became `$Strings_nl`).
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+`QbeGen.AddrOfVal` scans the whole VAR-actual note ring, and
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+`RestoreSession` restored `nn` but never cleared the ring — so the
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+grammar's suppressed parse-time `NoteAddr` entries survived into
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+`Lower` and a stale key could false-match. Fix: clear the ring in
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+`RestoreSession`. Output-neutral on `Showcase11`; corrected some latent
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+resolutions in the compiler's own image.
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+
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+### 4. Dead-code sweep
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+
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+`d730e80` (the `Can*` family, `LowerSession`/`LowerUnit`,
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+`SetLower`/`lowerRequested`), `e269828` (QbeGen orphans), `241c2c9`
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+(SymTab/QbeGen orphans), `b0ef2bf` (`AST.TxtLen`/`SetKind`),
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+`b4d9e25` (post-decoupling orphans: `SetOutName`, `FwdDesignator`,
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+`FwdAddrOper`, `IsExternal`, `MethUid`, `FieldOwner`). A tree-wide
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+scan (tests included) now reports **0** unreferenced procs.
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+
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+### 5. Value/emit decoupling
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+
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+The expression value is also the front-end constant evaluator
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+(`Expr`'s `q` feeds `SetSymVal`/`NoteConstVal`/`IsImm`/`ConstInt`), so
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+it could not just be dropped. Runtime results are marked with the
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+non-constant sentinel `"@"` (which `IsImm`/`ConstInt` reject);
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+constant folding (`NegFold`/`Fold2`/`StrFold`) and every check stay.
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+
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+- `6001af6` `SimExpr`, `5fb26e7` `Term`, `4f2afa0` `Expr`,
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+ `d469c78` `Fact` runtime builtins/calls.
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+- `90d2529` the **coupled change**: `Design`/`Fact`/`ArgList`/`ActParam`
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+ together, dropping the `NoteAddr`/`AddrOfVal` note chain from the
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+ grammar (kept for `Lower`) and replacing VAR-actual addressability
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+ with an AST-kind check (`NkDesignator`, or `NkStrLit`).
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+- `0667290` `Design`/`ResultComp`, `0ebe92e` assignment, `f59b784`
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+ remaining runtime value ops, `02f2526` `ProcHeading`'s output.
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+
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+### 6. `-lower` retired (`bcb93a5`)
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+
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+With one emitter, `-lower` no longer changed what was emitted — only
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+the image name for a byte-compare that compared `Lower` against itself.
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+`IsLowerParam`/`lowerTest`/`EndSession`'s `testSuffix` and the 23
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+`lower_ok`/`lower_ok_files` cases are gone; the covered programs are
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+still exercised by the `expect_run`/session cases. Suite 204 → 181.
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+
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+## Traps worth remembering
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+
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+- **`ArgList` alone can't be decoupled:** dropping its `CallBegin`
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+ (fewer `NewTemp`s) shifts the note-ring keys and breaks calls — 75
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+ suite failures. `Design`→`Fact`→`ArgList`→`ActParam` is one unit.
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+- **An empty `(. .)` action** in `ProcDecl` generated a bare `;` empty
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+ statement that **gm2 accepts but the V3 self-host grammar rejects** —
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+ the suite passed while the fixpoint failed.
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+
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+## What remains
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+
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+The grammar's remaining `QbeGen` calls are not removable emit:
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+
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+- the **value layer** (`CopyOp`, `IsImm`, `IntStr`, `Fold2`, `Norm*`,
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+ `Conv*`, `CharVal`, `StrFold`/`StrEq`, `CapQ`/`AbsQ`/`NotQ`,
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+ `UStrLen`) — computes constants and the `q` `Lower.NoteConstVal`
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+ consumes; and
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+- the **parser-state / lifecycle** (`SetModule`, `BeginFunc`/
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+ `FuncParam`/`EndFunc`/`AbortFunc`, `PushWith`/`PopWith`/`PushLoop`/
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+ `PopLoop`, `TopWith`/`TopLoop`/`LocFull`, `DeclStr`/`DeclUStr`,
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+ `SetLit`/`Ctor*`).
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+
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+Deleting `SaveSession`/`RestoreSession`/`SetNoEmit` (the last item)
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+requires the grammar to stop writing entirely, which means
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+reimplementing the parameter-scope bookkeeping (`FuncParam` needs
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+`BeginFunc`'s `nPar` reset) and the `WITH`/`EXIT` stacks outside
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+`QbeGen` — a reimplementation, not cleanup.
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+
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+## Fixpoint sizes across the work
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+
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+| step | bytes |
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+|---|---|
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+| flip | 3,553,701 |
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+| statements + declarations + bug fix | 3,538,557 |
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+| dead-code sweep | 3,420,733 |
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+| decoupling (expr layer) | 3,406,951 |
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+| decoupling complete (Design/Fact/calls/assignment/ProcHeading) | 3,377,935 |
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+| `-lower` retired + orphan cleanup | 3,367,634 |
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+
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+~186 KB smaller than at the flip, all green.
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