[llvm] [VPlan] Remove non-reductions after simplifications. (PR #176795)

[via llvm-commits]

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@@ -1510,6 +1510,11 @@ static void simplifyRecipe(VPSingleDefRecipe *Def, VPTypeAnalysis &TypeInfo) {
     return;
   }
 
+  VPIRValue *IRV;
+  if (Def->getNumOperands() == 1 &&
+      match(Def, m_ComputeReductionResult(m_VPIRValue(IRV))))
+    return Def->replaceAllUsesWith(IRV);
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ayalz wrote:

Worth a comment, essentially checking if the operand of ComputeReductionResult is scalar, and relying on the underlying assumption that all IRValues are scalar.

https://github.com/llvm/llvm-project/pull/176795