From 0afd0bc5facb63a96c706dc8a2468327ee3161da Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Mon, 27 Jan 2014 08:17:58 +0000 Subject: [PATCH] [vectorizer] Clean up the handling of unvectorized loop unrolling in the LoopVectorize pass. The logic here doesn't make much sense. We *only* unrolled if the unvectorized loop was a reduction loop with a single basic block *and* small loop body. The reduction part in particular doesn't make much sense. Instead, if we just fall through to the vectorized unroll logic it makes more sense of unrolling if there is a vectorized reduction that could be hacked on by the SLP vectorizer *or* if the loop is small. This is mostly a cleanup and nothing in the test suite really exercises this, but I did run benchmarks across this change and saw no really significant changes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200198 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Vectorize/LoopVectorize.cpp | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp index 9db66e7e693..66134bd95d0 100644 --- a/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -4995,19 +4995,9 @@ LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize, else if (UF < 1) UF = 1; - bool HasReductions = Legal->getReductionVars()->size(); - - // Decide if we want to unroll if we decided that it is legal to vectorize - // but not profitable. - if (VF == 1) { - if (TheLoop->getNumBlocks() > 1 || !HasReductions || - LoopCost > SmallLoopCost) - return 1; - - return UF; - } - - if (HasReductions) { + // Unroll if we vectorized this loop and there is a reduction that could + // benefit from unrolling. + if (VF > 1 && Legal->getReductionVars()->size()) { DEBUG(dbgs() << "LV: Unrolling because of reductions.\n"); return UF; }