codegen: fix bitcast of union values with inline_roots#61027
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vtjnash
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Look correct, though not very DRY
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When a union type contains members with mixed GC-pointer and non-pointer fields (e.g. a struct with both Vector and Int64 fields), codegen uses "split representation" where non-pointer data lives in v.V and GC roots are stored separately in v.inline_roots. The generic_bitcast codegen handler called ispointer()/data_pointer() which assert inline_roots.empty(), causing an assertion failure. Handle the inline_roots case before falling through to ispointer() by loading directly from v.V via maybe_decay_tracked(). This is correct because the dynamic runtime checks emitted earlier in the function (isprimitivetype + size match) guarantee that only primitive types with no GC pointers reach the load. Co-Authored-By: Claude Opus 4.6 <[email protected]>
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does this need backport? |
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Summary
inline_roots).generic_bitcastcalledispointer()/data_pointer()which assertinline_roots.empty(), causing an assertion failure.inline_rootscase by loading directly fromv.Vbefore falling through toispointer(). The dynamic runtime checks (isprimitivetype + size match) already guarantee only primitive types reach the load.Test plan
test/intrinsics.jlthat exercisesCore.Intrinsics.bitcaston a union containing a struct with GC-pointer fields (split representation).This PR was written with the assistance of generative AI (Claude).
🤖 Generated with Claude Code