[llvm] [VPlan] Implement interleaving as VPlan-to-VPlan transform. (PR #95842)

[via llvm-commits]

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@@ -428,14 +428,15 @@ Value *VPInstruction::generatePerPart(VPTransformState &State, unsigned Part) {
   }
   case VPInstruction::CanonicalIVIncrementForPart: {
     auto *IV = State.get(getOperand(0), VPIteration(0, 0));
-    if (Part == 0)
-      return IV;
-
-    // The canonical IV is incremented by the vectorization factor (num of SIMD
-    // elements) times the unroll part.
-    Value *Step = createStepForVF(Builder, IV->getType(), State.VF, Part);
-    return Builder.CreateAdd(IV, Step, Name, hasNoUnsignedWrap(),
-                             hasNoSignedWrap());
+    if (getNumOperands() == 2) {
+      // The canonical IV is incremented by the vectorization factor (num of
+      // SIMD elements) times the unroll part.
+      Value *Step = createStepForVF(Builder, IV->getType(), State.VF,
+                                    getInterleaveCount());
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ayalz wrote:

Does InterleaveCount here mean unroll part?

https://github.com/llvm/llvm-project/pull/95842