[llvm] [InstCombine] Mark as unknown the branch weights of packed integer selecting shifts (PR #162726)

[Mircea Trofin via llvm-commits]

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@@ -108,6 +109,11 @@ static Value *simplifyShiftSelectingPackedElement(Instruction *I,
       IC.Builder.CreateICmpEQ(ShrAmt, Constant::getNullValue(ShrAmt->getType()),
                               ShrAmt->getName() + ".z");
   Value *Select = IC.Builder.CreateSelect(ShrAmtZ, Lower, Upper);
+  // There is no existing !prof metadata we can derive the !prof metadata for
+  // this select.
+  if (auto *SI = dyn_cast<SelectInst>(Select))
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mtrofin wrote:

It may produce a Value, not an Instruction, because of folding.

https://github.com/llvm/llvm-project/pull/162726