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+# Lower phase — L7 (the flip): status and plan (2026-10-05)
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+
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+Branch **`ast-stage-c`**. L7 = "flip: lower from the AST instead of
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+inline; delete the inline emit + `Fwd*` machinery".
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+
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+## Why L7 is not incremental
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+
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+The flip makes `Lower` the sole emitter. The obstacle is that `QbeGen`
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+holds **one** session state, used by the inline emit *during* parse; a
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+per-unit `Lower` emit would be clobbered by the next unit's inline emit.
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+So the flip is a **big-bang**: either remove/suppress the grammar's 533
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+`QbeGen.*` call sites, or give `QbeGen` two states — neither is a
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+byte-verifiable step.
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+
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+The pragmatic path is therefore a **session re-emit**: collect every
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+unit's AST and re-emit the whole session with `Lower` after parsing.
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+That is byte-comparable against the legacy session image and becomes the
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+flip once the inline emit is removed.
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+
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+## Started (`d30abfd`, tag `v3-lower7-scaffold`)
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+
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+- `Lower.LowerSession/LowerOneUnit/MaterializeGlobals`.
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+- Driver (`compiler.frm`) collects `GetUnit()` per file and calls
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+ `Lower.LowerSession` under `-lower`.
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+- `SymTab.Materialize` makes a unit's own VAR/CONST visible in
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+ `globScope`, so `GlobalRef` resolves `"<unit>_<name>"` at session end
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+ (the unit scopes are closed by then).
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+- Removed `Lower.Reset` from the `M2` root so the owned tables persist
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+ across a session.
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+
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+Still scaffolding (inline emit untouched); suite **200/200**, FIXPOINT OK
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+(3,401,129 bytes).
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+
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+## Gaps found (all fixable, all required for the flip)
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+
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+1. **`DefUnit` builds no AST.** Its `ConstBlock/TypeBlock/VarBlock/
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+ ProcHeading` loop never `AstAppend`s, so a definition module's AST has
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+ no decls; its proc *headings* (which consume backend temps) cannot be
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+ replayed. Fix: append to `astDecl` in `DefUnit`.
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+2. **Owned-table size.** `MaxProc=64` / `MaxSym=512` are sized for one
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+ unit; a full-session re-emit needs every module's procs/vars. Growing
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+ them grows the compiler image (watch the 4 MiB `sessBuf`).
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+3. **Nested-module globals.** `QualNode(outer, name)` does not see a
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+ nested scope's non-exported globals; `ReenterGlobals` re-enters them
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+ but with `curMod = -1` (empty `mod`), so `GlobalRef` falls back to
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+ `$name` instead of `$<outer>_<name>`.
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+4. **Definition-module proc replay** must emit only the heading
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+ (`BeginFunc`/`FuncParam`/`AbortFunc`), like `LowerMethodHeadings`.
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+5. Possibly more, revealed once a full session is compared.
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+
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+## Plan
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+
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+1. Fix (1) and (4); grow tables (2) within the image budget.
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+2. Compare `Lower.LowerSession`'s image against the legacy session image
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+ for the compiler's own sources (the real test).
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+3. Fix the remaining gaps until the session image byte-matches.
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+4. Flip: remove the inline emit; keep `Lower` per unit; the fixpoint
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+ becomes the gate.
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