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LateLowerGCFrame: honor the "julia.safepoint" call-site marker - #63462
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This would also be useful for Enzyme, since it annotates calls more aggressively than Julia base. |
Calls tagged "julia.safepoint" are Julia calls whose memory effects codegen narrowed from inferred effects. They can still reach a GC safepoint, so LocalScan must treat them as safepoints regardless of what the memory effects claim, and the effects must be stripped before any post-lowering pass could use them against the now-explicit GC frame stores. This is the rooting half of re-landing #61394 (reverted in #62697, see #62613): rooting no longer depends on pass ordering having stripped the attributes first. Assisted-by: Claude Code (Fable 5.1)
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First of a 4-PR stack re-landing #61394 (reverted in #62697 because of #62613): #63462 → #63463 → #63464 → #63465.
Calls tagged with the string attribute
"julia.safepoint"are Julia calls whose memory effects codegen narrowed from inferred effects (that emission lands in #63464). They can still reach a GC safepoint, so:LocalScantreats tagged calls as safepoints regardless of what their memory effects claim, so rooting never depends on pass ordering having stripped the attributes first (the failure mode identified inadd_fn_attrs_for_effectsmarks calls that can write memory asmemory(read: argmem)#62613).runOnFunctionstrips the memory effects (and anyreadnoneon the gcstack argument) from tagged calls before any post-lowering pass could use them against the now-explicit GC frame stores.On master nothing emits the marker yet, so this is a pure hardening change with no behavioral effect; it exists so the safety net is in place before #63464 relies on it. Subsumes the
LocalScangate from #62698.Tests: five new cases in
test/llvmpasses/late-lower-gc.ll(argmem-only, readonly, indirect call, gcstackreadnonestripping, and a negative control for a genuinely readonly helper).🤖 Generated with Claude Code