[llvm] [VPlan] Use VPlan predecessors in VPWidenPHIRecipe (NFC). (PR #126388)

[via llvm-commits]

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@@ -1991,19 +1990,8 @@ class VPWidenPHIRecipe : public VPSingleDefRecipe {
              VPSlotTracker &SlotTracker) const override;
 #endif
 
-  /// Adds a pair (\p IncomingV, \p IncomingBlock) to the phi.
-  void addIncoming(VPValue *IncomingV, VPBasicBlock *IncomingBlock) {
-    addOperand(IncomingV);
-    IncomingBlocks.push_back(IncomingBlock);
-  }
-
   /// Returns the \p I th incoming VPBasicBlock.
-  VPBasicBlock *getIncomingBlock(unsigned I) { return IncomingBlocks[I]; }
-
-  /// Set the \p I th incoming VPBasicBlock to \p IncomingBlock.
-  void setIncomingBlock(unsigned I, VPBasicBlock *IncomingBlock) {
-    IncomingBlocks[I] = IncomingBlock;
-  }
+  VPBasicBlock *getIncomingBlock(unsigned I);
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ayalz wrote:

Making VPWidenPHIRecipe be a VPInstruction would simplify "buildLoop" VPlan produced by HCFGBuilder, making it more consistent ("Widen"? All recipes are scalar at this point) and aligned with "wrapInput" VPlan/Region/Blocks which consist of VPIRInstructions - for phi's and non-phi's alike (with the option of introducing other recipes between them).

https://github.com/llvm/llvm-project/pull/126388