From ce77ab0c2457389d083a21d498b9ae16dab5dc05 Mon Sep 17 00:00:00 2001 From: Nadav Rotem Date: Wed, 31 Oct 2012 03:31:07 +0000 Subject: LoopVectorize: Do not vectorize loops with tiny constant trip counts. llvm-svn: 167101 --- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'llvm/lib/Transforms/Vectorize/LoopVectorize.cpp') diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index e82dfa2454f..fd728bd6168 100644 --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -1145,6 +1145,14 @@ bool LoopVectorizationLegality::canVectorize() { return false; } + // Do not loop-vectorize loops with a tiny trip count. + unsigned TC = SE->getSmallConstantTripCount(TheLoop, BB); + if (TC > 0 && TC < 16) { + DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " << + "This loop is not worth vectorizing.\n"); + return false; + } + DEBUG(dbgs() << "LV: We can vectorize this loop!\n"); // Okay! We can vectorize. At this point we don't have any other mem analysis -- cgit v1.2.3