[PATCH] D147964: [VPlan] Introduce new entry block to VPlan for early SCEV expansion.

[Ayal Zaks via Phabricator via llvm-commits]

Ayal added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:3261
+       [ ] <-- old preheader - loop iteration number check and SCEVs in Plan's
+     /  |      preheader are expanded here. Eventually all required SCEV
+    /   |      expansion should happen here.
----------------
(post-commit nit): so have we reached this "Eventually" situation?


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Comment at: llvm/lib/Transforms/Vectorize/VPlan.cpp:1139-1140
   else {
-    VPBasicBlock *Preheader = Plan.getEntry();
     Expanded = new VPExpandSCEVRecipe(Expr, SE);
-    Preheader->appendRecipe(Expanded->getDefiningRecipe());
+    Plan.getPreheader()->appendRecipe(Expanded->getDefiningRecipe());
   }
----------------
fhahn wrote:
> Ayal wrote:
> > fhahn wrote:
> > > Ayal wrote:
> > > > nit: can cast instead of getting defined recipe.
> > > Will address separately.
> > All ExpandSCEVRecipes are placed in preheader, rather than vector preheader / entry, right?
> Yep!
(post-commit nit): worth updating documented figure, see above.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147964/new/

https://reviews.llvm.org/D147964