[PATCH] D64275: [InstCombine] Generalize InstCombiner::foldAndOrOfICmpsOfAndWithPow2().

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:908-910
+        B = Builder.CreateLShr(
+            ConstantInt::get(Ty, APInt::getSignMask(Ty->getScalarSizeInBits())),
+            B2);
----------------
lebedev.ri wrote:
> To be pointed out, this indeed creates an instruction while we don't know yet whether we will be able to do the fold,
> not great, but i think this is the smallest evil, the alternative solution would indeed be uglier..
Hmm...do we have a test where the temporary instruction is created, but the fold fails?
Last time I made that mistake, we infinite looped: the temporary instruction gets created and deleted triggering another round of combining and repeat forever.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D64275/new/

https://reviews.llvm.org/D64275