[PATCH] D111300: [VPlan] Keep induction recipes in header.

[Ayal Zaks via Phabricator via llvm-commits]

Ayal added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:9333
 
         RecipeBuilder.setRecipe(Instr, Recipe);
+        if (isa<VPWidenIntOrFpInductionRecipe>(Recipe)) {
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Worth a comment why VPWidenIntOrFpInductionRecipe deserves special displacement.

(Easiest to handle here; just raising some related thoughts:
This is somewhat reminiscent of SinkAfter, in that recipes created next to their triggering ingredient need to be placed elsewhere; but SinkAfter is quite cumbersome. Other conceptual approaches may be to search for Trunc's when processing an IV Phi and produce a recipe for each (but current scheme produces a single recipe per triggering ingredient), and first hoisting the Trunc to appear in the header (i.e., cleaning up SinkAfter - perhaps once VPlan starts by representing the original scalar loop).)


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:9339
+          else
+            Header->appendRecipe(Recipe);
+        } else
----------------
Suffice to have  `Header->insert(Recipe, Header->getFirstNonPhi())` for both cases?

May be worth wrapping within an insertPhi() method.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D111300/new/

https://reviews.llvm.org/D111300