[llvm] [InstCombine] Extend Fold of Zero-extended Bit Test (PR #102100)

[Nikita Popov via llvm-commits]

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@@ -997,7 +997,8 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
         X = Builder.CreateNot(X);
       Value *Lshr = Builder.CreateLShr(X, ShAmt);
       Value *And1 = Builder.CreateAnd(Lshr, ConstantInt::get(X->getType(), 1));
-      return replaceInstUsesWith(Zext, And1);
+      return replaceInstUsesWith(
+          Zext, Builder.CreateZExtOrTrunc(And1, Zext.getType()));
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nikic wrote:

I think in the ICMP_EQ case, we may also have to check that the shl is one use now? Otherwise we replace zext+icmp+and with not+lshr+and+zext/trunc, which is more instructions.

https://github.com/llvm/llvm-project/pull/102100