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SLPVectorizer: Bring back the insertelement patch (r205965) with fixes

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When can't assume a vectorized tree is rooted in an instruction. The IRBuilder
could have constant folded it. When we rebuild the build_vector (the series of
InsertElement instructions) use the last original InsertElement instruction. The
vectorized tree root is guaranteed to be before it.

Also, we can't assume that the n-th InsertElement inserts the n-th element into
a vector.

This reverts r207746 which reverted the revert of the revert of r205018 or so.

Fixes the test case in PR19621.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207939 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer
2014-05-04 17:10:15 +00:00
parent 8a3751f813
commit 28a739b4dc
3 changed files with 210 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

99
lib/Transforms/Vectorize/SLPVectorizer.cpp
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@ -31,6 +31,7 @@
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/Verifier.h"
@ -357,13 +358,13 @@ public:
/// A negative number means that this is profitable.
int getTreeCost();
/// Construct a vectorizable tree that starts at \p Roots and is possibly
/// used by a reduction of \p RdxOps.
void buildTree(ArrayRef<Value *> Roots, ValueSet *RdxOps = 0);
/// Construct a vectorizable tree that starts at \p Roots, ignoring users for
/// the purpose of scheduling and extraction in the \p UserIgnoreLst.
void buildTree(ArrayRef<Value *> Roots,
ArrayRef<Value *> UserIgnoreLst = None);
/// Clear the internal data structures that are created by 'buildTree'.
void deleteTree() {
RdxOps = 0;
VectorizableTree.clear();
ScalarToTreeEntry.clear();
MustGather.clear();
@ -526,8 +527,8 @@ private:
return I.first->second;
}
/// Reduction operators.
ValueSet *RdxOps;
/// List of users to ignore during scheduling and that don't need extracting.
ArrayRef<Value *> UserIgnoreList;
// Analysis and block reference.
Function *F;
@ -542,9 +543,10 @@ private:
IRBuilder<> Builder;
};
void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
void BoUpSLP::buildTree(ArrayRef<Value *> Roots,
ArrayRef<Value *> UserIgnoreLst) {
deleteTree();
RdxOps = Rdx;
UserIgnoreList = UserIgnoreLst;
if (!getSameType(Roots))
return;
buildTree_rec(Roots, 0);
@ -576,8 +578,9 @@ void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
if (!UserInst)
continue;
// Ignore uses that are part of the reduction.
if (Rdx && std::find(Rdx->begin(), Rdx->end(), UserInst) != Rdx->end())
// Ignore users in the user ignore list.
if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(), UserInst) !=
UserIgnoreList.end())
continue;
DEBUG(dbgs() << "SLP: Need to extract:" << *U << " from lane " <<
@ -708,8 +711,9 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth) {
continue;
}
// This user is part of the reduction.
if (RdxOps && RdxOps->count(UI))
// Ignore users in the user ignore list.
if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(), UI) !=
UserIgnoreList.end())
continue;
// Make sure that we can schedule this unknown user.
@ -1747,8 +1751,9 @@ Value *BoUpSLP::vectorizeTree() {
DEBUG(dbgs() << "SLP: \tvalidating user:" << *U << ".\n");
assert((ScalarToTreeEntry.count(U) ||
// It is legal to replace the reduction users by undef.
(RdxOps && RdxOps->count(U))) &&
// It is legal to replace users in the ignorelist by undef.
(std::find(UserIgnoreList.begin(), UserIgnoreList.end(), U) !=
UserIgnoreList.end())) &&
"Replacing out-of-tree value with undef");
}
#endif
@ -1954,8 +1959,11 @@ private:
bool tryToVectorizePair(Value *A, Value *B, BoUpSLP &R);
/// \brief Try to vectorize a list of operands.
/// \@param BuildVector A list of users to ignore for the purpose of
/// scheduling and that don't need extracting.
/// \returns true if a value was vectorized.
bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R);
bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
ArrayRef<Value *> BuildVector = None);
/// \brief Try to vectorize a chain that may start at the operands of \V;
bool tryToVectorize(BinaryOperator *V, BoUpSLP &R);
@ -2128,7 +2136,8 @@ bool SLPVectorizer::tryToVectorizePair(Value *A, Value *B, BoUpSLP &R) {
return tryToVectorizeList(VL, R);
}
bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R) {
bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
ArrayRef<Value *> BuildVector) {
if (VL.size() < 2)
return false;
@ -2178,13 +2187,38 @@ bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R) {
<< "\n");
ArrayRef<Value *> Ops = VL.slice(i, OpsWidth);
R.buildTree(Ops);
ArrayRef<Value *> BuildVectorSlice;
if (!BuildVector.empty())
BuildVectorSlice = BuildVector.slice(i, OpsWidth);
R.buildTree(Ops, BuildVectorSlice);
int Cost = R.getTreeCost();
if (Cost < -SLPCostThreshold) {
DEBUG(dbgs() << "SLP: Vectorizing list at cost:" << Cost << ".\n");
R.vectorizeTree();
Value *VectorizedRoot = R.vectorizeTree();
// Reconstruct the build vector by extracting the vectorized root. This
// way we handle the case where some elements of the vector are undefined.
// (return (inserelt <4 xi32> (insertelt undef (opd0) 0) (opd1) 2))
if (!BuildVectorSlice.empty()) {
// The insert point is the last build vector instruction. The vectorized
// root will precede it. This guarantees that we get an instruction. The
// vectorized tree could have been constant folded.
Instruction *InsertAfter = cast<Instruction>(BuildVectorSlice.back());
unsigned VecIdx = 0;
for (auto &V : BuildVectorSlice) {
IRBuilder<true, NoFolder> Builder(
++BasicBlock::iterator(InsertAfter));
InsertElementInst *IE = cast<InsertElementInst>(V);
Instruction *Extract = cast<Instruction>(Builder.CreateExtractElement(
VectorizedRoot, Builder.getInt32(VecIdx++)));
IE->setOperand(1, Extract);
IE->removeFromParent();
IE->insertAfter(Extract);
InsertAfter = IE;
}
}
// Move to the next bundle.
i += VF - 1;
Changed = true;
@ -2293,7 +2327,7 @@ static Value *createRdxShuffleMask(unsigned VecLen, unsigned NumEltsToRdx,
/// *p =
///
class HorizontalReduction {
SmallPtrSet<Value *, 16> ReductionOps;
SmallVector<Value *, 16> ReductionOps;
SmallVector<Value *, 32> ReducedVals;
BinaryOperator *ReductionRoot;
@ -2387,7 +2421,7 @@ public:
// We need to be able to reassociate the adds.
if (!TreeN->isAssociative())
return false;
ReductionOps.insert(TreeN);
ReductionOps.push_back(TreeN);
}
// Retract.
Stack.pop_back();
@ -2424,7 +2458,7 @@ public:
for (; i < NumReducedVals - ReduxWidth + 1; i += ReduxWidth) {
ArrayRef<Value *> ValsToReduce(&ReducedVals[i], ReduxWidth);
V.buildTree(ValsToReduce, &ReductionOps);
V.buildTree(ValsToReduce, ReductionOps);
// Estimate cost.
int Cost = V.getTreeCost() + getReductionCost(TTI, ReducedVals[i]);
@ -2543,13 +2577,16 @@ private:
///
/// Returns true if it matches
///
static bool findBuildVector(InsertElementInst *IE,
SmallVectorImpl<Value *> &Ops) {
if (!isa<UndefValue>(IE->getOperand(0)))
static bool findBuildVector(InsertElementInst *FirstInsertElem,
SmallVectorImpl<Value *> &BuildVector,
SmallVectorImpl<Value *> &BuildVectorOpds) {
if (!isa<UndefValue>(FirstInsertElem->getOperand(0)))
return false;
InsertElementInst *IE = FirstInsertElem;
while (true) {
Ops.push_back(IE->getOperand(1));
BuildVector.push_back(IE);
BuildVectorOpds.push_back(IE->getOperand(1));
if (IE->use_empty())
return false;
@ -2720,12 +2757,16 @@ bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
}
// Try to vectorize trees that start at insertelement instructions.
if (InsertElementInst *IE = dyn_cast<InsertElementInst>(it)) {
SmallVector<Value *, 8> Ops;
if (!findBuildVector(IE, Ops))
if (InsertElementInst *FirstInsertElem = dyn_cast<InsertElementInst>(it)) {
SmallVector<Value *, 16> BuildVector;
SmallVector<Value *, 16> BuildVectorOpds;
if (!findBuildVector(FirstInsertElem, BuildVector, BuildVectorOpds))
continue;
if (tryToVectorizeList(Ops, R)) {
// Vectorize starting with the build vector operands ignoring the
// BuildVector instructions for the purpose of scheduling and user
// extraction.
if (tryToVectorizeList(BuildVectorOpds, R, BuildVector)) {
Changed = true;
it = BB->begin();
e = BB->end();