luxufan 232698dc17 [Local][InstCombine][GVN] Handle !noundef metadata in combineMetadata ...

Handle !noundef metadata in comhineMetadata. The behavior of violating
!noundef metadata is undefined behavior. So if K dominates J, we can
preserve it uncontionally, otherwise, we preserve it if both K and J
have !noundef metadata been set.

This patch also makes !noundef metadata added in KnownIDs when doing
instruction combine for phi node or global value numbering for loads.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D142801

2023-02-02 14:25:13 +08:00

58 KiB

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