[llvm] [VPlan] Verify dominance for incoming values of phi-like recipes. (PR #124838)

[via llvm-commits]

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@@ -175,6 +175,12 @@ bool VPlanVerifier::verifyEVLRecipe(const VPInstruction &EVL) const {
   });
 }
 
+/// Return true if \p R is a VPIRInstruction wrapping a phi.
+static bool isVPIRInstructionPhi(const VPRecipeBase &R) {
+  auto *VPIRI = dyn_cast<VPIRInstruction>(&R);
+  return VPIRI && isa<PHINode>(VPIRI->getInstruction());
+}
+
 bool VPlanVerifier::verifyVPBasicBlock(const VPBasicBlock *VPBB) {
   if (!verifyPhiRecipes(VPBB))
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ayalz wrote:

```
  // Verify that defs in VPBB dominate all their uses. The current
  // implementation is still incomplete.
```
does the above second sentence from below still hold?

https://github.com/llvm/llvm-project/pull/124838