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LoopVectorize: Do not vectorize loops with tiny constant trip counts.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167101 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2012-10-31 03:31:07 +00:00
parent 42d43351b2
commit 5b2c4dc5f8
2 changed files with 41 additions and 0 deletions
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8
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -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