[llvm] [InstCombine] Do not fold `shufflevector(select)` if the select condition is a vector (PR #113993)

[Yingwei Zheng via llvm-commits]

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@@ -2902,8 +2902,12 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
 
   if (match(RHS, m_Constant())) {
     if (auto *SI = dyn_cast<SelectInst>(LHS)) {
-      if (Instruction *I = FoldOpIntoSelect(SVI, SI))
-        return I;
+      // We cannot do this fold for elementwise select since ShuffleVector is
+      // not elementwise.
+      if (SI->getCondition()->getType()->isIntegerTy()) {
+        if (Instruction *I = FoldOpIntoSelect(SVI, SI))
+          return I;
+      }
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dtcxzyw wrote:

There is a counterexample: https://alive2.llvm.org/ce/z/s8saCx.


https://github.com/llvm/llvm-project/pull/113993