[PATCH] D144492: [InstCombine] Support multiple comparisons in foldAllocaCmp()

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:925
+      // have other contributions from a select/phi operand.
+      // TODO: We could check whether getUnderlyingObjects() reduces to one
+      // object.
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goldstein.w.n wrote:
> I don't understand this TODO, isn't `getUnderlyingObject(*U) == Alloca` doing just that?
getUnderlyingObject() does not look through phi nodes.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:956
+      eraseInstFromFunction(*ICmp);
+      Changed = true;
+      break;
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goldstein.w.n wrote:
> Is there a reason this isn't in `InstructionSimplify`?
This can't be in InstSimplify because it is a correctness requirement that *all* comparisons of the alloca are replaced at the same time, something that InstSimplify cannot guarantee.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D144492/new/

https://reviews.llvm.org/D144492