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ARM Cost model: Use the size of vector registers and widest vectorizable instruction to determine the max vectorization factor.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172010 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2013-01-09 22:29:00 +00:00
parent d2f8216ba4
commit 14925e6b88
9 changed files with 153 additions and 5 deletions
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51
lib/Transforms/Vectorize/LoopVectorize.cpp
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@@ -113,9 +113,6 @@ static const unsigned MaxLoopSizeThreshold = 32;
/// number of pointers. Notice that the check is quadratic!
static const unsigned RuntimeMemoryCheckThreshold = 4;
/// This is the highest vector width that we try to generate.
static const unsigned MaxVectorSize = 8;
namespace {
// Forward declarations.
@@ -523,6 +520,10 @@ public:
/// possible.
unsigned selectVectorizationFactor(bool OptForSize, unsigned UserVF);
/// \returns 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();
/// \return The most profitable unroll factor.
/// If UserUF is non-zero then this method finds the best unroll-factor
@@ -2621,6 +2622,20 @@ LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
unsigned TC = SE->getSmallConstantTripCount(TheLoop, TheLoop->getLoopLatch());
DEBUG(dbgs() << "LV: Found trip count:"<<TC<<"\n");
unsigned WidestType = getWidestType();
unsigned WidestRegister = TTI.getRegisterBitWidth(true);
unsigned MaxVectorSize = WidestRegister / WidestType;
DEBUG(dbgs() << "LV: The Widest type: " << WidestType << " bits.\n");
DEBUG(dbgs() << "LV: The Widest register is:" << WidestRegister << "bits.\n");
if (MaxVectorSize == 0) {
DEBUG(dbgs() << "LV: The target has no vector registers.\n");
return 1;
}
assert(MaxVectorSize <= 32 && "Did not expect to pack so many elements"
" into one vector.");
unsigned VF = MaxVectorSize;
// If we optimize the program for size, avoid creating the tail loop.
@@ -2672,6 +2687,36 @@ LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
return Width;
}
unsigned LoopVectorizationCostModel::getWidestType() {
unsigned MaxWidth = 8;
// For each block.
for (Loop::block_iterator bb = TheLoop->block_begin(),
be = TheLoop->block_end(); bb != be; ++bb) {
BasicBlock *BB = *bb;
// For each instruction in the loop.
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
if (Legal->isUniformAfterVectorization(it))
continue;
Type *T = it->getType();
if (StoreInst *ST = dyn_cast<StoreInst>(it))
T = ST->getValueOperand()->getType();
// PHINodes and pointers are difficult to analyze, but we catch all other
// uses of the types in other instructions.
if (isa<PHINode>(it) || T->isPointerTy() || T->isVoidTy())
continue;
MaxWidth = std::max(MaxWidth, T->getScalarSizeInBits());
}
}
return MaxWidth;
}
unsigned
LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
unsigned UserUF) {