[llvm-commits] [llvm] r173691 - Vectorization Factor clarification
Renato Golin
renato.golin at linaro.org
Mon Jan 28 08:02:45 PST 2013
Author: rengolin
Date: Mon Jan 28 10:02:45 2013
New Revision: 173691
URL: http://llvm.org/viewvc/llvm-project?rev=173691&view=rev
Log:
Vectorization Factor clarification
Modified:
llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=173691&r1=173690&r2=173691&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Mon Jan 28 10:02:45 2013
@@ -516,14 +516,18 @@ public:
const TargetTransformInfo &TTI)
: TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI) {}
+ /// Information about vectorization costs
+ struct VectorizationFactor {
+ unsigned Width; // Vector width with best cost
+ unsigned Cost; // Cost of the loop with that width
+ };
/// \return The most profitable vectorization factor and the cost of that VF.
/// This method checks every power of two up to VF. If UserVF is not ZERO
/// then this vectorization factor will be selected if vectorization is
/// possible.
- std::pair<unsigned, unsigned>
- selectVectorizationFactor(bool OptForSize, unsigned UserVF);
+ VectorizationFactor selectVectorizationFactor(bool OptForSize, unsigned UserVF);
- /// \returns The size (in bits) of the widest type in the code that
+ /// \return The size (in bits) of the widest type in the code that
/// needs to be vectorized. We ignore values that remain scalar such as
/// 64 bit loop indices.
unsigned getWidestType();
@@ -633,24 +637,23 @@ struct LoopVectorize : public LoopPass {
}
// Select the optimal vectorization factor.
- std::pair<unsigned, unsigned> VFPair;
- VFPair = CM.selectVectorizationFactor(OptForSize, VectorizationFactor);
+ LoopVectorizationCostModel::VectorizationFactor VF;
+ VF = CM.selectVectorizationFactor(OptForSize, VectorizationFactor);
// Select the unroll factor.
unsigned UF = CM.selectUnrollFactor(OptForSize, VectorizationUnroll,
- VFPair.first, VFPair.second);
- unsigned VF = VFPair.first;
+ VF.Width, VF.Cost);
- if (VF == 1) {
+ if (VF.Width == 1) {
DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial.\n");
return false;
}
- DEBUG(dbgs() << "LV: Found a vectorizable loop ("<< VF << ") in "<<
+ DEBUG(dbgs() << "LV: Found a vectorizable loop ("<< VF.Width << ") in "<<
F->getParent()->getModuleIdentifier()<<"\n");
DEBUG(dbgs() << "LV: Unroll Factor is " << UF << "\n");
// If we decided that it is *legal* to vectorizer the loop then do it.
- InnerLoopVectorizer LB(L, SE, LI, DT, DL, VF, UF);
+ InnerLoopVectorizer LB(L, SE, LI, DT, DL, VF.Width, UF);
LB.vectorize(&LVL);
DEBUG(verifyFunction(*L->getHeader()->getParent()));
@@ -2675,12 +2678,14 @@ bool LoopVectorizationLegality::hasCompu
return AR->isAffine();
}
-std::pair<unsigned, unsigned>
+LoopVectorizationCostModel::VectorizationFactor
LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
unsigned UserVF) {
+ // Width 1 means no vectorize
+ VectorizationFactor Factor = { 1U, 0U };
if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
DEBUG(dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n");
- return std::make_pair(1U, 0U);
+ return Factor;
}
// Find the trip count.
@@ -2708,7 +2713,7 @@ LoopVectorizationCostModel::selectVector
// If we are unable to calculate the trip count then don't try to vectorize.
if (TC < 2) {
DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
- return std::make_pair(1U, 0U);
+ return Factor;
}
// Find the maximum SIMD width that can fit within the trip count.
@@ -2721,7 +2726,7 @@ LoopVectorizationCostModel::selectVector
// zero then we require a tail.
if (VF < 2) {
DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
- return std::make_pair(1U, 0U);
+ return Factor;
}
}
@@ -2729,7 +2734,8 @@ LoopVectorizationCostModel::selectVector
assert(isPowerOf2_32(UserVF) && "VF needs to be a power of two");
DEBUG(dbgs() << "LV: Using user VF "<<UserVF<<".\n");
- return std::make_pair(UserVF, 0U);
+ Factor.Width = UserVF;
+ return Factor;
}
float Cost = expectedCost(1);
@@ -2749,8 +2755,9 @@ LoopVectorizationCostModel::selectVector
}
DEBUG(dbgs() << "LV: Selecting VF = : "<< Width << ".\n");
- unsigned LoopCost = VF * Cost;
- return std::make_pair(Width, LoopCost);
+ Factor.Width = Width;
+ Factor.Cost = Width * Cost;
+ return Factor;
}
unsigned LoopVectorizationCostModel::getWidestType() {
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