[VPlan] Add Name argument to VPWidenPHIRecipe. NFC (#129527)

This allows a different IR name for the generated phi to be used. This
is split off from #118638 and helps remove some of the diffs in it.

Author: lukel97

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -1932,11 +1932,16 @@ class VPScalarPHIRecipe : public VPHeaderPHIRecipe {
 /// exactly 2 incoming values, the first from the predecessor of the region and
 /// the second from the exiting block of the region.
 class VPWidenPHIRecipe : public VPSingleDefRecipe {
+  /// Name to use for the generated IR instruction for the widened phi.
+  std::string Name;
+
 public:
   /// Create a new VPWidenPHIRecipe for \p Phi with start value \p Start and
   /// debug location \p DL.
-  VPWidenPHIRecipe(PHINode *Phi, VPValue *Start = nullptr, DebugLoc DL = {})
-      : VPSingleDefRecipe(VPDef::VPWidenPHISC, ArrayRef<VPValue *>(), Phi, DL) {
+  VPWidenPHIRecipe(PHINode *Phi, VPValue *Start = nullptr, DebugLoc DL = {},
+                   const Twine &Name = "")
+      : VPSingleDefRecipe(VPDef::VPWidenPHISC, ArrayRef<VPValue *>(), Phi, DL),
+        Name(Name.str()) {
     if (Start)
       addOperand(Start);
   }

llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp

@@ -315,7 +315,7 @@ void PlainCFGBuilder::createVPInstructionsForVPBB(VPBasicBlock *VPBB,
       // Phi node's operands may have not been visited at this point. We create
       // an empty VPInstruction that we will fix once the whole plain CFG has
       // been built.
-      NewR = new VPWidenPHIRecipe(Phi, nullptr, Phi->getDebugLoc());
+      NewR = new VPWidenPHIRecipe(Phi, nullptr, Phi->getDebugLoc(), "vec.phi");
       VPBB->appendRecipe(NewR);
       if (isHeaderBB(Phi->getParent(), LI->getLoopFor(Phi->getParent()))) {
         // Header phis need to be fixed after the VPBB for the latch has been

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -3608,7 +3608,7 @@ void VPWidenPHIRecipe::execute(VPTransformState &State) {
   State.setDebugLocFrom(getDebugLoc());
   Value *Op0 = State.get(getOperand(0));
   Type *VecTy = Op0->getType();
-  Value *VecPhi = State.Builder.CreatePHI(VecTy, 2, "vec.phi");
+  Value *VecPhi = State.Builder.CreatePHI(VecTy, 2, Name);
   State.set(this, VecPhi);
 }