[llvm] [VPlan] Compute induction end values in VPlan. (PR #112145)

[via llvm-commits]

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@@ -9718,13 +9711,14 @@ void VPDerivedIVRecipe::execute(VPTransformState &State) {
     State.Builder.setFastMathFlags(FPBinOp->getFastMathFlags());
 
   Value *Step = State.get(getStepValue(), VPLane(0));
-  Value *CanonicalIV = State.get(getOperand(1), VPLane(0));
+  Value *Index = State.get(getOperand(1), VPLane(0));
   Value *DerivedIV = emitTransformedIndex(
-      State.Builder, CanonicalIV, getStartValue()->getLiveInIRValue(), Step,
-      Kind, cast_if_present<BinaryOperator>(FPBinOp));
+      State.Builder, Index, getStartValue()->getLiveInIRValue(), Step, Kind,
+      cast_if_present<BinaryOperator>(FPBinOp));
   DerivedIV->setName(Name);
-  assert(DerivedIV != CanonicalIV && "IV didn't need transforming?");
-
+  // Index may only be set to constant 0 in prepareToExecute.
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ayalz wrote:

I still seem to be missing something here. The fact that prepareToExecute() creates the vector trip count (typically to non zero?) implies that derived IVs that are based on it will miss the opportunity to be folded by simplifyRecipes(), because it's too late.

https://github.com/llvm/llvm-project/pull/112145