[PATCH] D75961: [InstCombine] reduce demand-limited bool math to logic

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp:457
   case Instruction::Add:
+    if (DemandedMask.isSignMask()) {
+      // Try to convert bool math to logic:
----------------
Wouldn't it be sufficient to check that the LSB is not demanded? I don't think we care that specifically the MSB is demanded, any of the top bits could be.


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  https://reviews.llvm.org/D75961/new/

https://reviews.llvm.org/D75961