Put the threshold magic number in a variable.

llvm-svn: 167134

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 40235ef1043..94e56a17131 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -75,6 +75,9 @@ static cl::opt<unsigned>
 VectorizationFactor("force-vector-width", cl::init(0), cl::Hidden,
           cl::desc("Set the default vectorization width. Zero is autoselect."));
 
+/// We don't vectorize loops with a known constant trip count below this number.
+const int TinyTripCountThreshold = 16;
+
 namespace {
 
 // Forward declarations.
@@ -1147,7 +1150,7 @@ bool LoopVectorizationLegality::canVectorize() {
 
   // Do not loop-vectorize loops with a tiny trip count.
   unsigned TC = SE->getSmallConstantTripCount(TheLoop, BB);
-  if (TC > 0 && TC < 16) {
+  if (TC > 0 && TC < TinyTripCountThreshold) {
     DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " <<
           "This loop is not worth vectorizing.\n");
     return false;