[PATCH] D67805: [LV] Allow vectorization of hot short trip count loops with epilog.

[Evgeniy via Phabricator via llvm-commits]

ebrevnov created this revision.
Herald added subscribers: llvm-commits, rkruppe, zzheng, hiraditya.
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Currently we reject to vectorize loops with epilog if trip count less than 16 (as defined by TinyTripCountVectorThreshold) and loop is cold accoriding to profile. Thus in absence of profile summary information we will never vectorize such loops even if cost model can prove profitability. With this change we try to improve the situation by using block execution count information (if available) to judge if loop is hot relativly to function entry.

Idealy we should be using loop size and expected perf gain from  cost model in addition to loop hotness to make the decicion but that would be much bigger change and can be a follow up step.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D67805

Files:
  llvm/include/llvm/Transforms/Utils/SizeOpts.h
  llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
  llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
  llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
  llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
  llvm/lib/Transforms/Utils/SizeOpts.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/hot_short_tc_loop.ll

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