[PATCH] D105806: [LV] Print remark when loop cannot be vectorized due to invalid costs.

Mon Jul 12 13:34:43 PDT 2021

fhahn added inline comments.

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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:1680
   /// the factor width.
-  VectorizationCostTy expectedCost(ElementCount VF);

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Could you extend the doc-comment here to include the new argument?

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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:6132
+          OS << ")\n";
+        OS << "\t" << *InstructionVFPair.first << "\t(";
+        Current = InstructionVFPair.first;
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Ideally remarks should be easy to understand for end-users, who do not know about LLVM IR (they specifically are not only targeted at LLVM developers). Instead of printing IR directly, it might be more user-friendly to just say something like `call to function sin` instead of the plain LLVM IR call. Not sure if we have such pretty-printing anywhere else already though.

Including the file/line info where the instruction appears might be a good first step.

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Comment at: llvm/test/Transforms/LoopVectorize/AArch64/scalable-call.ll:100

+; CHECK-REMARKS: UserVF ignored because of invalid costs.
+; CHECK-REMARKS-NEXT: Instructions with invalid costs prevent vectorization for certain VFs:
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could you add debug locations to the test and also check that the correct locations are used for the remark?

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105806/new/

https://reviews.llvm.org/D105806