[llvm] [InstCombine] Fold zext(icmp ne X, C) to X - C when X is in (C, C+1) (PR #208914)

[Andreas Jonson via llvm-commits]

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@@ -1407,6 +1407,28 @@ Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp,
         return replaceInstUsesWith(Zext, IntCast);
       }
     }
+
+    ConstantRange CR = computeConstantRange(Cmp->getOperand(0), false, SQ);
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andjo403 wrote:

computeConstantRange (is recursive so kind of slow) is done for all cmp instructions only needed for EQ/NE

https://github.com/llvm/llvm-project/pull/208914