[llvm] [LV] Remove common extends and selects in CSE (PR #147731)

[Sander de Smalen via llvm-commits]

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@@ -920,6 +920,8 @@ bool Instruction::hasSameSpecialState(const Instruction *I2,
   if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I1))
     return GEP->getSourceElementType() ==
            cast<GetElementPtrInst>(I2)->getSourceElementType();
+  if (const CastInst *Cast = dyn_cast<CastInst>(I1))
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sdesmalen-arm wrote:

FWIW, I couldn't find any dedicated tests for `Instruction::isSameOperationAs`, so perhaps the changes to existing tests would be sufficient?

https://github.com/llvm/llvm-project/pull/147731