[6.3] SILCombine: don't sink forwarding instructions with address operands #86040
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Contributor
eeckstein
commented
Dec 15, 2025
eeckstein
commented
- Explanation: Fixes a SIL verifier crash caused by a wrong peephole optimization in SILCombine. The optimization sinks forwarding instructions down the control flow. However, we don't do memory lifetime analysis for this peephole optimization. Therefore we can't risk sinking instructions with address operands out of the addressed memory's lifetime.
- Risk: Low. It's a simple change which makes the peephole optimization more conservative
- Testing: Tested by a lit test.
- Issue: rdar://166240751
- Reviewer: @atrick
- Main branch PR: SILCombine: don't sink forwarding instructions with address operands #86005
We don't do memory lifetime analysis for this peephole optimization. Therefore we can't risk sinking instructions with address operands out of the addressed memory's lifetime. For example: ``` %3 = mark_dependence %2 on %1 : $*T // must not be moved after the destroy_addr destroy_addr %1 ``` Fixes a verifier crash rdar://166240751
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@swift-ci test |
DougGregor
approved these changes
Dec 16, 2025
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