29 lines
1.2 KiB
Markdown
29 lines
1.2 KiB
Markdown
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Scope Hints (No-Op, Design Notes)
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Purpose
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- Provide zero-cost markers from front/macro to MIR builder so later passes can validate/control PHI placement and scope structure without changing semantics.
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Current Hints (src/mir/hints.rs)
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- HintKind::LoopHeader(id): at loop header block begin
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- HintKind::LoopLatch(id): at loop backedge/latch
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- HintKind::ScopeEnter(id), ScopeLeave(id): lexical scope begin/end
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- HintKind::JoinResult(var): for if-join when both branches assign the same var
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Producers (wired, no-op)
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- Loop builder: emits LoopHeader/LoopLatch
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- If builder: emits JoinResult for simple same-var assignments
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Planned Injection Points
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- Macro-normalized If/Match: emit JoinResult when we build branch assignments into the same LHS
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- Statement blocks: on entering/leaving Local groups, emit ScopeEnter/Leave (id may be per-Program statement index)
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- Function bodies: ScopeEnter at entry, ScopeLeave before Return/End
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Policy
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- Hints do not affect codegen; they are purely observational until a validator consumes them.
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- Keep IDs stable within a single compilation unit; no cross-unit meaning required.
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Next
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- Wire ScopeEnter/Leave in MirBuilder for function entry/exit and block constructs.
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- Add a simple debug dump when NYASH_MIR_TRACE_HINTS=1.
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