[PATCH] D113223: [VPlan] Add VPCanonicalIVRecipe, partly retire createInductionVariable.

[Florian Hahn via Phabricator via llvm-commits]

fhahn marked an inline comment as done.
fhahn added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/VPlan.cpp:919
+      auto *ICmp = cast<Instruction>(
+          State->Builder.CreateICmpEQ(Next, State->VectorTripCount));
+      TermBr->setCondition(ICmp);
----------------
fhahn wrote:
> Ayal wrote:
> > Ayal wrote:
> > > fhahn wrote:
> > > > Ayal wrote:
> > > > > Introducing the ICmpEQ feeding TermBr should ideally be done by an appropriate (BCT) recipe in the normal course of VPlan::execute() stage 2 above, rather than during this backedge-rewiring stage 3.
> > > > I added a TODO and this should be addressed soon in a follow-up patch. Or should those changes also be pulled in here?
> > > > I added a TODO and this should be addressed soon in a follow-up patch. Or should those changes also be pulled in here?
> > > 
> > > As you prefer. A BranchOnCount recipe could potentially take care of the Increment[NUW]-feeding-the-ICmpEQ-feeding-the-branch better, while defining the single VPValue to feed back the CanonicalIVPHI. It could be introduced here instead of Increment[NUW] et al., or replace them in the TODO follow-up patch.
> > If the ICmpEQ is to be generated here/now connected to InductionIncrement and branch, suggest to do so separately rather than inside a loop taking care of rewiring header phis. The InductionIncrement can be located directly at the end of the Exit, analogous to getCanonicalIV(), conceptually as part of a terminating inc-cmp-br idiom.
> Moved outside the loop.
I put up D116479 to add a `cmp-and-branch` VPInstruction opcode as a follow-up.


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https://reviews.llvm.org/D113223