[PATCH] D114528: [LV] Make sure VF doesn't exceed compile time known TC

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

Sounds sensible to me.



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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:1747
+                                           ElementCount UserVF,
+                                           bool foldTailByMasking);
 
----------------
foldTailByMasking -> FoldTailByMasking


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:6078
+      (!foldTailByMasking || isPowerOf2_32(ConstTripCount))) {
     // We need to clamp the VF to be the ConstTripCount. There is no point in
     // choosing a higher viable VF as done in the loop below. If
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Can you update this comment..


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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:6083
     LLVM_DEBUG(dbgs() << "LV: Clamping the MaxVF to the constant trip count: "
                       << ConstTripCount << "\n");
+    return ElementCount::getFixed(PowerOf2Floor(ConstTripCount));
----------------
.. and this debug message.


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Comment at: llvm/test/Transforms/LoopVectorize/X86/known_TC.ll:7
 
 ; TODO: Make sure selected VF for the main loop doesn't exceed TC.
 ; TODO: Make sure selected VF for the epilog loop doesn't exceed remaining TC.
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This can be removed now?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D114528/new/

https://reviews.llvm.org/D114528