[PATCH] D157187: [InstCombine] Propagate the nsw for instruction neg-sub

[Allen zhong via Phabricator via llvm-commits]

Allen marked an inline comment as done.
Allen added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp:2069
+        // Make sure the sub and neg have the same type flag.
+        if (I.hasNoUnsignedWrap() && Op1Inst->hasNoUnsignedWrap())
+          InstOp1->setHasNoUnsignedWrap();
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nikic wrote:
> You don't seem to have test coverage for the nuw case, and it seems pretty useless to boot. `sub nuw 0, %x` can only be non-poison if `%x` is zero. This is not a useful case to handle.
Thanks, I delete the nuw case.


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  https://reviews.llvm.org/D157187/new/

https://reviews.llvm.org/D157187