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

[Florian Hahn via llvm-commits]

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@@ -1215,24 +1221,32 @@ void VPWidenIntOrFpInductionRecipe::execute(VPTransformState &State) {
     MulOp = Instruction::FMul;
   }
 
-  // Multiply the vectorization factor by the step using integer or
-  // floating-point arithmetic as appropriate.
-  Type *StepType = Step->getType();
-  Value *RuntimeVF;
-  if (Step->getType()->isFloatingPointTy())
-    RuntimeVF = getRuntimeVFAsFloat(Builder, StepType, State.VF);
-  else
-    RuntimeVF = getRuntimeVF(Builder, StepType, State.VF);
-  Value *Mul = Builder.CreateBinOp(MulOp, Step, RuntimeVF);
-
-  // Create a vector splat to use in the induction update.
-  //
-  // FIXME: If the step is non-constant, we create the vector splat with
-  //        IRBuilder. IRBuilder can constant-fold the multiply, but it doesn't
-  //        handle a constant vector splat.
-  Value *SplatVF = isa<Constant>(Mul)
-                       ? ConstantVector::getSplat(State.VF, cast<Constant>(Mul))
-                       : Builder.CreateVectorSplat(State.VF, Mul);
+  Value *SplatVF;
+  if (getNumOperands() == 4) {
+    // Need to create stuff in PH.
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fhahn wrote:

Yep I'll see if this can be done separately.

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