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9660ebb398
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
Arnold Schwaighofer 9660ebb398 SLPVectorize: Put horizontal reductions feeding a store under separate flag 
Put them under a separate flag for experimentation. They are more likely to
interfere with loop vectorization which happens later in the pass pipeline.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191371 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-25 14:02:32 +00:00

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//===- SLPVectorizer.cpp - A bottom up SLP Vectorizer ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// This pass implements the Bottom Up SLP vectorizer. It detects consecutive
// stores that can be put together into vector-stores. Next, it attempts to
// construct vectorizable tree using the use-def chains. If a profitable tree
// was found, the SLP vectorizer performs vectorization on the tree.
//
// The pass is inspired by the work described in the paper:
// "Loop-Aware SLP in GCC" by Ira Rosen, Dorit Nuzman, Ayal Zaks.
//
//===----------------------------------------------------------------------===//
#define SV_NAME "slp-vectorizer"
#define DEBUG_TYPE "SLP"
#include "llvm/Transforms/Vectorize.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <map>
using namespace llvm;
static cl::opt<int>
SLPCostThreshold("slp-threshold", cl::init(0), cl::Hidden,
cl::desc("Only vectorize if you gain more than this "
"number "));
static cl::opt<bool>
ShouldVectorizeHor("slp-vectorize-hor", cl::init(false), cl::Hidden,
cl::desc("Attempt to vectorize horizontal reductions"));
static cl::opt<bool> ShouldStartVectorizeHorAtStore(
"slp-vectorize-hor-store", cl::init(false), cl::Hidden,
cl::desc(
"Attempt to vectorize horizontal reductions feeding into a store"));
namespace {
static const unsigned MinVecRegSize = 128;
static const unsigned RecursionMaxDepth = 12;
/// RAII pattern to save the insertion point of the IR builder.
class BuilderLocGuard {
public:
BuilderLocGuard(IRBuilder<> &B) : Builder(B), Loc(B.GetInsertPoint()),
DbgLoc(B.getCurrentDebugLocation()) {}
~BuilderLocGuard() {
Builder.SetCurrentDebugLocation(DbgLoc);
if (Loc)
Builder.SetInsertPoint(Loc);
}
private:
// Prevent copying.
BuilderLocGuard(const BuilderLocGuard &);
BuilderLocGuard &operator=(const BuilderLocGuard &);
IRBuilder<> &Builder;
AssertingVH<Instruction> Loc;
DebugLoc DbgLoc;
};
/// A helper class for numbering instructions in multiple blocks.
/// Numbers start at zero for each basic block.
struct BlockNumbering {
BlockNumbering(BasicBlock *Bb) : BB(Bb), Valid(false) {}
BlockNumbering() : BB(0), Valid(false) {}
void numberInstructions() {
unsigned Loc = 0;
InstrIdx.clear();
InstrVec.clear();
// Number the instructions in the block.
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
InstrIdx[it] = Loc++;
InstrVec.push_back(it);
assert(InstrVec[InstrIdx[it]] == it && "Invalid allocation");
}
Valid = true;
}
int getIndex(Instruction *I) {
assert(I->getParent() == BB && "Invalid instruction");
if (!Valid)
numberInstructions();
assert(InstrIdx.count(I) && "Unknown instruction");
return InstrIdx[I];
}
Instruction *getInstruction(unsigned loc) {
if (!Valid)
numberInstructions();
assert(InstrVec.size() > loc && "Invalid Index");
return InstrVec[loc];
}
void forget() { Valid = false; }
private:
/// The block we are numbering.
BasicBlock *BB;
/// Is the block numbered.
bool Valid;
/// Maps instructions to numbers and back.
SmallDenseMap<Instruction *, int> InstrIdx;
/// Maps integers to Instructions.
SmallVector<Instruction *, 32> InstrVec;
};
/// \returns the parent basic block if all of the instructions in \p VL
/// are in the same block or null otherwise.
static BasicBlock *getSameBlock(ArrayRef<Value *> VL) {
Instruction *I0 = dyn_cast<Instruction>(VL[0]);
if (!I0)
return 0;
BasicBlock *BB = I0->getParent();
for (int i = 1, e = VL.size(); i < e; i++) {
Instruction *I = dyn_cast<Instruction>(VL[i]);
if (!I)
return 0;
if (BB != I->getParent())
return 0;
}
return BB;
}
/// \returns True if all of the values in \p VL are constants.
static bool allConstant(ArrayRef<Value *> VL) {
for (unsigned i = 0, e = VL.size(); i < e; ++i)
if (!isa<Constant>(VL[i]))
return false;
return true;
}
/// \returns True if all of the values in \p VL are identical.
static bool isSplat(ArrayRef<Value *> VL) {
for (unsigned i = 1, e = VL.size(); i < e; ++i)
if (VL[i] != VL[0])
return false;
return true;
}
/// \returns The opcode if all of the Instructions in \p VL have the same
/// opcode, or zero.
static unsigned getSameOpcode(ArrayRef<Value *> VL) {
Instruction *I0 = dyn_cast<Instruction>(VL[0]);
if (!I0)
return 0;
unsigned Opcode = I0->getOpcode();
for (int i = 1, e = VL.size(); i < e; i++) {
Instruction *I = dyn_cast<Instruction>(VL[i]);
if (!I || Opcode != I->getOpcode())
return 0;
}
return Opcode;
}
/// \returns The type that all of the values in \p VL have or null if there
/// are different types.
static Type* getSameType(ArrayRef<Value *> VL) {
Type *Ty = VL[0]->getType();
for (int i = 1, e = VL.size(); i < e; i++)
if (VL[i]->getType() != Ty)
return 0;
return Ty;
}
/// \returns True if the ExtractElement instructions in VL can be vectorized
/// to use the original vector.
static bool CanReuseExtract(ArrayRef<Value *> VL) {
assert(Instruction::ExtractElement == getSameOpcode(VL) && "Invalid opcode");
// Check if all of the extracts come from the same vector and from the
// correct offset.
Value *VL0 = VL[0];
ExtractElementInst *E0 = cast<ExtractElementInst>(VL0);
Value *Vec = E0->getOperand(0);
// We have to extract from the same vector type.
unsigned NElts = Vec->getType()->getVectorNumElements();
if (NElts != VL.size())
return false;
// Check that all of the indices extract from the correct offset.
ConstantInt *CI = dyn_cast<ConstantInt>(E0->getOperand(1));
if (!CI || CI->getZExtValue())
return false;
for (unsigned i = 1, e = VL.size(); i < e; ++i) {
ExtractElementInst *E = cast<ExtractElementInst>(VL[i]);
ConstantInt *CI = dyn_cast<ConstantInt>(E->getOperand(1));
if (!CI || CI->getZExtValue() != i || E->getOperand(0) != Vec)
return false;
}
return true;
}
/// Bottom Up SLP Vectorizer.
class BoUpSLP {
public:
typedef SmallVector<Value *, 8> ValueList;
typedef SmallVector<Instruction *, 16> InstrList;
typedef SmallPtrSet<Value *, 16> ValueSet;
typedef SmallVector<StoreInst *, 8> StoreList;
BoUpSLP(Function *Func, ScalarEvolution *Se, DataLayout *Dl,
TargetTransformInfo *Tti, AliasAnalysis *Aa, LoopInfo *Li,
DominatorTree *Dt) :
F(Func), SE(Se), DL(Dl), TTI(Tti), AA(Aa), LI(Li), DT(Dt),
Builder(Se->getContext()) {
// Setup the block numbering utility for all of the blocks in the
// function.
for (Function::iterator it = F->begin(), e = F->end(); it != e; ++it) {
BasicBlock *BB = it;
BlocksNumbers[BB] = BlockNumbering(BB);
}
}
/// \brief Vectorize the tree that starts with the elements in \p VL.
/// Returns the vectorized root.
Value *vectorizeTree();
/// \returns the vectorization cost of the subtree that starts at \p VL.
/// 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);
/// Clear the internal data structures that are created by 'buildTree'.
void deleteTree() {
RdxOps = 0;
VectorizableTree.clear();
ScalarToTreeEntry.clear();
MustGather.clear();
ExternalUses.clear();
MemBarrierIgnoreList.clear();
}
/// \returns true if the memory operations A and B are consecutive.
bool isConsecutiveAccess(Value *A, Value *B);
/// \brief Perform LICM and CSE on the newly generated gather sequences.
void optimizeGatherSequence();
private:
struct TreeEntry;
/// \returns the cost of the vectorizable entry.
int getEntryCost(TreeEntry *E);
/// This is the recursive part of buildTree.
void buildTree_rec(ArrayRef<Value *> Roots, unsigned Depth);
/// Vectorize a single entry in the tree.
Value *vectorizeTree(TreeEntry *E);
/// Vectorize a single entry in the tree, starting in \p VL.
Value *vectorizeTree(ArrayRef<Value *> VL);
/// \returns the pointer to the vectorized value if \p VL is already
/// vectorized, or NULL. They may happen in cycles.
Value *alreadyVectorized(ArrayRef<Value *> VL) const;
/// \brief Take the pointer operand from the Load/Store instruction.
/// \returns NULL if this is not a valid Load/Store instruction.
static Value *getPointerOperand(Value *I);
/// \brief Take the address space operand from the Load/Store instruction.
/// \returns -1 if this is not a valid Load/Store instruction.
static unsigned getAddressSpaceOperand(Value *I);
/// \returns the scalarization cost for this type. Scalarization in this
/// context means the creation of vectors from a group of scalars.
int getGatherCost(Type *Ty);
/// \returns the scalarization cost for this list of values. Assuming that
/// this subtree gets vectorized, we may need to extract the values from the
/// roots. This method calculates the cost of extracting the values.
int getGatherCost(ArrayRef<Value *> VL);
/// \returns the AA location that is being access by the instruction.
AliasAnalysis::Location getLocation(Instruction *I);
/// \brief Checks if it is possible to sink an instruction from
/// \p Src to \p Dst.
/// \returns the pointer to the barrier instruction if we can't sink.
Value *getSinkBarrier(Instruction *Src, Instruction *Dst);
/// \returns the index of the last instrucion in the BB from \p VL.
int getLastIndex(ArrayRef<Value *> VL);
/// \returns the Instruction in the bundle \p VL.
Instruction *getLastInstruction(ArrayRef<Value *> VL);
/// \brief Set the Builder insert point to one after the last instruction in
/// the bundle
void setInsertPointAfterBundle(ArrayRef<Value *> VL);
/// \returns a vector from a collection of scalars in \p VL.
Value *Gather(ArrayRef<Value *> VL, VectorType *Ty);
struct TreeEntry {
TreeEntry() : Scalars(), VectorizedValue(0), LastScalarIndex(0),
NeedToGather(0) {}
/// \returns true if the scalars in VL are equal to this entry.
bool isSame(ArrayRef<Value *> VL) const {
assert(VL.size() == Scalars.size() && "Invalid size");
for (int i = 0, e = VL.size(); i != e; ++i)
if (VL[i] != Scalars[i])
return false;
return true;
}
/// A vector of scalars.
ValueList Scalars;
/// The Scalars are vectorized into this value. It is initialized to Null.
Value *VectorizedValue;
/// The index in the basic block of the last scalar.
int LastScalarIndex;
/// Do we need to gather this sequence ?
bool NeedToGather;
};
/// Create a new VectorizableTree entry.
TreeEntry *newTreeEntry(ArrayRef<Value *> VL, bool Vectorized) {
VectorizableTree.push_back(TreeEntry());
int idx = VectorizableTree.size() - 1;
TreeEntry *Last = &VectorizableTree[idx];
Last->Scalars.insert(Last->Scalars.begin(), VL.begin(), VL.end());
Last->NeedToGather = !Vectorized;
if (Vectorized) {
Last->LastScalarIndex = getLastIndex(VL);
for (int i = 0, e = VL.size(); i != e; ++i) {
assert(!ScalarToTreeEntry.count(VL[i]) && "Scalar already in tree!");
ScalarToTreeEntry[VL[i]] = idx;
}
} else {
Last->LastScalarIndex = 0;
MustGather.insert(VL.begin(), VL.end());
}
return Last;
}
/// -- Vectorization State --
/// Holds all of the tree entries.
std::vector<TreeEntry> VectorizableTree;
/// Maps a specific scalar to its tree entry.
SmallDenseMap<Value*, int> ScalarToTreeEntry;
/// A list of scalars that we found that we need to keep as scalars.
ValueSet MustGather;
/// This POD struct describes one external user in the vectorized tree.
struct ExternalUser {
ExternalUser (Value *S, llvm::User *U, int L) :
Scalar(S), User(U), Lane(L){};
// Which scalar in our function.
Value *Scalar;
// Which user that uses the scalar.
llvm::User *User;
// Which lane does the scalar belong to.
int Lane;
};
typedef SmallVector<ExternalUser, 16> UserList;
/// A list of values that need to extracted out of the tree.
/// This list holds pairs of (Internal Scalar : External User).
UserList ExternalUses;
/// A list of instructions to ignore while sinking
/// memory instructions. This map must be reset between runs of getCost.
ValueSet MemBarrierIgnoreList;
/// Holds all of the instructions that we gathered.
SetVector<Instruction *> GatherSeq;
/// Numbers instructions in different blocks.
DenseMap<BasicBlock *, BlockNumbering> BlocksNumbers;
/// Reduction operators.
ValueSet *RdxOps;
// Analysis and block reference.
Function *F;
ScalarEvolution *SE;
DataLayout *DL;
TargetTransformInfo *TTI;
AliasAnalysis *AA;
LoopInfo *LI;
DominatorTree *DT;
/// Instruction builder to construct the vectorized tree.
IRBuilder<> Builder;
};
void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
deleteTree();
RdxOps = Rdx;
if (!getSameType(Roots))
return;
buildTree_rec(Roots, 0);
// Collect the values that we need to extract from the tree.
for (int EIdx = 0, EE = VectorizableTree.size(); EIdx < EE; ++EIdx) {
TreeEntry *Entry = &VectorizableTree[EIdx];
// For each lane:
for (int Lane = 0, LE = Entry->Scalars.size(); Lane != LE; ++Lane) {
Value *Scalar = Entry->Scalars[Lane];
// No need to handle users of gathered values.
if (Entry->NeedToGather)
continue;
for (Value::use_iterator User = Scalar->use_begin(),
UE = Scalar->use_end(); User != UE; ++User) {
DEBUG(dbgs() << "SLP: Checking user:" << **User << ".\n");
bool Gathered = MustGather.count(*User);
// Skip in-tree scalars that become vectors.
if (ScalarToTreeEntry.count(*User) && !Gathered) {
DEBUG(dbgs() << "SLP: \tInternal user will be removed:" <<
**User << ".\n");
int Idx = ScalarToTreeEntry[*User]; (void) Idx;
assert(!VectorizableTree[Idx].NeedToGather && "Bad state");
continue;
}
Instruction *UserInst = dyn_cast<Instruction>(*User);
if (!UserInst)
continue;
// Ignore uses that are part of the reduction.
if (Rdx && std::find(Rdx->begin(), Rdx->end(), UserInst) != Rdx->end())
continue;
DEBUG(dbgs() << "SLP: Need to extract:" << **User << " from lane " <<
Lane << " from " << *Scalar << ".\n");
ExternalUses.push_back(ExternalUser(Scalar, *User, Lane));
}
}
}
}
void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth) {
bool SameTy = getSameType(VL); (void)SameTy;
assert(SameTy && "Invalid types!");
if (Depth == RecursionMaxDepth) {
DEBUG(dbgs() << "SLP: Gathering due to max recursion depth.\n");
newTreeEntry(VL, false);
return;
}
// Don't handle vectors.
if (VL[0]->getType()->isVectorTy()) {
DEBUG(dbgs() << "SLP: Gathering due to vector type.\n");
newTreeEntry(VL, false);
return;
}
if (StoreInst *SI = dyn_cast<StoreInst>(VL[0]))
if (SI->getValueOperand()->getType()->isVectorTy()) {
DEBUG(dbgs() << "SLP: Gathering due to store vector type.\n");
newTreeEntry(VL, false);
return;
}
// If all of the operands are identical or constant we have a simple solution.
if (allConstant(VL) || isSplat(VL) || !getSameBlock(VL) ||
!getSameOpcode(VL)) {
DEBUG(dbgs() << "SLP: Gathering due to C,S,B,O. \n");
newTreeEntry(VL, false);
return;
}
// We now know that this is a vector of instructions of the same type from
// the same block.
// Check if this is a duplicate of another entry.
if (ScalarToTreeEntry.count(VL[0])) {
int Idx = ScalarToTreeEntry[VL[0]];
TreeEntry *E = &VectorizableTree[Idx];
for (unsigned i = 0, e = VL.size(); i != e; ++i) {
DEBUG(dbgs() << "SLP: \tChecking bundle: " << *VL[i] << ".\n");
if (E->Scalars[i] != VL[i]) {
DEBUG(dbgs() << "SLP: Gathering due to partial overlap.\n");
newTreeEntry(VL, false);
return;
}
}
DEBUG(dbgs() << "SLP: Perfect diamond merge at " << *VL[0] << ".\n");
return;
}
// Check that none of the instructions in the bundle are already in the tree.
for (unsigned i = 0, e = VL.size(); i != e; ++i) {
if (ScalarToTreeEntry.count(VL[i])) {
DEBUG(dbgs() << "SLP: The instruction (" << *VL[i] <<
") is already in tree.\n");
newTreeEntry(VL, false);
return;
}
}
// If any of the scalars appears in the table OR it is marked as a value that
// needs to stat scalar then we need to gather the scalars.
for (unsigned i = 0, e = VL.size(); i != e; ++i) {
if (ScalarToTreeEntry.count(VL[i]) || MustGather.count(VL[i])) {
DEBUG(dbgs() << "SLP: Gathering due to gathered scalar. \n");
newTreeEntry(VL, false);
return;
}
}
// Check that all of the users of the scalars that we want to vectorize are
// schedulable.
Instruction *VL0 = cast<Instruction>(VL[0]);
int MyLastIndex = getLastIndex(VL);
BasicBlock *BB = cast<Instruction>(VL0)->getParent();
for (unsigned i = 0, e = VL.size(); i != e; ++i) {
Instruction *Scalar = cast<Instruction>(VL[i]);
DEBUG(dbgs() << "SLP: Checking users of " << *Scalar << ". \n");
for (Value::use_iterator U = Scalar->use_begin(), UE = Scalar->use_end();
U != UE; ++U) {
DEBUG(dbgs() << "SLP: \tUser " << **U << ". \n");
Instruction *User = dyn_cast<Instruction>(*U);
if (!User) {
DEBUG(dbgs() << "SLP: Gathering due unknown user. \n");
newTreeEntry(VL, false);
return;
}
// We don't care if the user is in a different basic block.
BasicBlock *UserBlock = User->getParent();
if (UserBlock != BB) {
DEBUG(dbgs() << "SLP: User from a different basic block "
<< *User << ". \n");
continue;
}
// If this is a PHINode within this basic block then we can place the
// extract wherever we want.
if (isa<PHINode>(*User)) {
DEBUG(dbgs() << "SLP: \tWe can schedule PHIs:" << *User << ". \n");
continue;
}
// Check if this is a safe in-tree user.
if (ScalarToTreeEntry.count(User)) {
int Idx = ScalarToTreeEntry[User];
int VecLocation = VectorizableTree[Idx].LastScalarIndex;
if (VecLocation <= MyLastIndex) {
DEBUG(dbgs() << "SLP: Gathering due to unschedulable vector. \n");
newTreeEntry(VL, false);
return;
}
DEBUG(dbgs() << "SLP: In-tree user (" << *User << ") at #" <<
VecLocation << " vector value (" << *Scalar << ") at #"
<< MyLastIndex << ".\n");
continue;
}
// This user is part of the reduction.
if (RdxOps && RdxOps->count(User))
continue;
// Make sure that we can schedule this unknown user.
BlockNumbering &BN = BlocksNumbers[BB];
int UserIndex = BN.getIndex(User);
if (UserIndex < MyLastIndex) {
DEBUG(dbgs() << "SLP: Can't schedule extractelement for "
<< *User << ". \n");
newTreeEntry(VL, false);
return;
}
}
}
// Check that every instructions appears once in this bundle.
for (unsigned i = 0, e = VL.size(); i < e; ++i)
for (unsigned j = i+1; j < e; ++j)
if (VL[i] == VL[j]) {
DEBUG(dbgs() << "SLP: Scalar used twice in bundle.\n");
newTreeEntry(VL, false);
return;
}
// Check that instructions in this bundle don't reference other instructions.
// The runtime of this check is O(N * N-1 * uses(N)) and a typical N is 4.
for (unsigned i = 0, e = VL.size(); i < e; ++i) {
for (Value::use_iterator U = VL[i]->use_begin(), UE = VL[i]->use_end();
U != UE; ++U) {
for (unsigned j = 0; j < e; ++j) {
if (i != j && *U == VL[j]) {
DEBUG(dbgs() << "SLP: Intra-bundle dependencies!" << **U << ". \n");
newTreeEntry(VL, false);
return;
}
}
}
}
DEBUG(dbgs() << "SLP: We are able to schedule this bundle.\n");
unsigned Opcode = getSameOpcode(VL);
// Check if it is safe to sink the loads or the stores.
if (Opcode == Instruction::Load || Opcode == Instruction::Store) {
Instruction *Last = getLastInstruction(VL);
for (unsigned i = 0, e = VL.size(); i < e; ++i) {
if (VL[i] == Last)
continue;
Value *Barrier = getSinkBarrier(cast<Instruction>(VL[i]), Last);
if (Barrier) {
DEBUG(dbgs() << "SLP: Can't sink " << *VL[i] << "\n down to " << *Last
<< "\n because of " << *Barrier << ". Gathering.\n");
newTreeEntry(VL, false);
return;
}
}
}
switch (Opcode) {
case Instruction::PHI: {
PHINode *PH = dyn_cast<PHINode>(VL0);
// Check for terminator values (e.g. invoke).
for (unsigned j = 0; j < VL.size(); ++j)
for (unsigned i = 0, e = PH->getNumIncomingValues(); i < e; ++i) {
TerminatorInst *Term = dyn_cast<TerminatorInst>(cast<PHINode>(VL[j])->getIncomingValue(i));
if (Term) {
DEBUG(dbgs() << "SLP: Need to swizzle PHINodes (TerminatorInst use).\n");
newTreeEntry(VL, false);
return;
}
}
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of PHINodes.\n");
for (unsigned i = 0, e = PH->getNumIncomingValues(); i < e; ++i) {
ValueList Operands;
// Prepare the operand vector.
for (unsigned j = 0; j < VL.size(); ++j)
Operands.push_back(cast<PHINode>(VL[j])->getIncomingValue(i));
buildTree_rec(Operands, Depth + 1);
}
return;
}
case Instruction::ExtractElement: {
bool Reuse = CanReuseExtract(VL);
if (Reuse) {
DEBUG(dbgs() << "SLP: Reusing extract sequence.\n");
}
newTreeEntry(VL, Reuse);
return;
}
case Instruction::Load: {
// Check if the loads are consecutive or of we need to swizzle them.
for (unsigned i = 0, e = VL.size() - 1; i < e; ++i)
if (!isConsecutiveAccess(VL[i], VL[i + 1])) {
newTreeEntry(VL, false);
DEBUG(dbgs() << "SLP: Need to swizzle loads.\n");
return;
}
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of loads.\n");
return;
}
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::FPExt:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::SIToFP:
case Instruction::UIToFP:
case Instruction::Trunc:
case Instruction::FPTrunc:
case Instruction::BitCast: {
Type *SrcTy = VL0->getOperand(0)->getType();
for (unsigned i = 0; i < VL.size(); ++i) {
Type *Ty = cast<Instruction>(VL[i])->getOperand(0)->getType();
if (Ty != SrcTy || Ty->isAggregateType() || Ty->isVectorTy()) {
newTreeEntry(VL, false);
DEBUG(dbgs() << "SLP: Gathering casts with different src types.\n");
return;
}
}
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of casts.\n");
for (unsigned i = 0, e = VL0->getNumOperands(); i < e; ++i) {
ValueList Operands;
// Prepare the operand vector.
for (unsigned j = 0; j < VL.size(); ++j)
Operands.push_back(cast<Instruction>(VL[j])->getOperand(i));
buildTree_rec(Operands, Depth+1);
}
return;
}
case Instruction::ICmp:
case Instruction::FCmp: {
// Check that all of the compares have the same predicate.
CmpInst::Predicate P0 = dyn_cast<CmpInst>(VL0)->getPredicate();
Type *ComparedTy = cast<Instruction>(VL[0])->getOperand(0)->getType();
for (unsigned i = 1, e = VL.size(); i < e; ++i) {
CmpInst *Cmp = cast<CmpInst>(VL[i]);
if (Cmp->getPredicate() != P0 ||
Cmp->getOperand(0)->getType() != ComparedTy) {
newTreeEntry(VL, false);
DEBUG(dbgs() << "SLP: Gathering cmp with different predicate.\n");
return;
}
}
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of compares.\n");
for (unsigned i = 0, e = VL0->getNumOperands(); i < e; ++i) {
ValueList Operands;
// Prepare the operand vector.
for (unsigned j = 0; j < VL.size(); ++j)
Operands.push_back(cast<Instruction>(VL[j])->getOperand(i));
buildTree_rec(Operands, Depth+1);
}
return;
}
case Instruction::Select:
case Instruction::Add:
case Instruction::FAdd:
case Instruction::Sub:
case Instruction::FSub:
case Instruction::Mul:
case Instruction::FMul:
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::FDiv:
case Instruction::URem:
case Instruction::SRem:
case Instruction::FRem:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor: {
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of bin op.\n");
for (unsigned i = 0, e = VL0->getNumOperands(); i < e; ++i) {
ValueList Operands;
// Prepare the operand vector.
for (unsigned j = 0; j < VL.size(); ++j)
Operands.push_back(cast<Instruction>(VL[j])->getOperand(i));
buildTree_rec(Operands, Depth+1);
}
return;
}
case Instruction::Store: {
// Check if the stores are consecutive or of we need to swizzle them.
for (unsigned i = 0, e = VL.size() - 1; i < e; ++i)
if (!isConsecutiveAccess(VL[i], VL[i + 1])) {
newTreeEntry(VL, false);
DEBUG(dbgs() << "SLP: Non consecutive store.\n");
return;
}
newTreeEntry(VL, true);
DEBUG(dbgs() << "SLP: added a vector of stores.\n");
ValueList Operands;
for (unsigned j = 0; j < VL.size(); ++j)
Operands.push_back(cast<Instruction>(VL[j])->getOperand(0));
// We can ignore these values because we are sinking them down.
MemBarrierIgnoreList.insert(VL.begin(), VL.end());
buildTree_rec(Operands, Depth + 1);
return;
}
default:
newTreeEntry(VL, false);
DEBUG(dbgs() << "SLP: Gathering unknown instruction.\n");
return;
}
}
int BoUpSLP::getEntryCost(TreeEntry *E) {
ArrayRef<Value*> VL = E->Scalars;
Type *ScalarTy = VL[0]->getType();
if (StoreInst *SI = dyn_cast<StoreInst>(VL[0]))
ScalarTy = SI->getValueOperand()->getType();
VectorType *VecTy = VectorType::get(ScalarTy, VL.size());
if (E->NeedToGather) {
if (allConstant(VL))
return 0;
if (isSplat(VL)) {
return TTI->getShuffleCost(TargetTransformInfo::SK_Broadcast, VecTy, 0);
}
return getGatherCost(E->Scalars);
}
assert(getSameOpcode(VL) && getSameType(VL) && getSameBlock(VL) &&
"Invalid VL");
Instruction *VL0 = cast<Instruction>(VL[0]);
unsigned Opcode = VL0->getOpcode();
switch (Opcode) {
case Instruction::PHI: {
return 0;
}
case Instruction::ExtractElement: {
if (CanReuseExtract(VL))
return 0;
return getGatherCost(VecTy);
}
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::FPExt:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::SIToFP:
case Instruction::UIToFP:
case Instruction::Trunc:
case Instruction::FPTrunc:
case Instruction::BitCast: {
Type *SrcTy = VL0->getOperand(0)->getType();
// Calculate the cost of this instruction.
int ScalarCost = VL.size() * TTI->getCastInstrCost(VL0->getOpcode(),
VL0->getType(), SrcTy);
VectorType *SrcVecTy = VectorType::get(SrcTy, VL.size());
int VecCost = TTI->getCastInstrCost(VL0->getOpcode(), VecTy, SrcVecTy);
return VecCost - ScalarCost;
}
case Instruction::FCmp:
case Instruction::ICmp:
case Instruction::Select:
case Instruction::Add:
case Instruction::FAdd:
case Instruction::Sub:
case Instruction::FSub:
case Instruction::Mul:
case Instruction::FMul:
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::FDiv:
case Instruction::URem:
case Instruction::SRem:
case Instruction::FRem:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor: {
// Calculate the cost of this instruction.
int ScalarCost = 0;
int VecCost = 0;
if (Opcode == Instruction::FCmp || Opcode == Instruction::ICmp ||
Opcode == Instruction::Select) {
VectorType *MaskTy = VectorType::get(Builder.getInt1Ty(), VL.size());
ScalarCost = VecTy->getNumElements() *
TTI->getCmpSelInstrCost(Opcode, ScalarTy, Builder.getInt1Ty());
VecCost = TTI->getCmpSelInstrCost(Opcode, VecTy, MaskTy);
} else {
ScalarCost = VecTy->getNumElements() *
TTI->getArithmeticInstrCost(Opcode, ScalarTy);
VecCost = TTI->getArithmeticInstrCost(Opcode, VecTy);
}
return VecCost - ScalarCost;
}
case Instruction::Load: {
// Cost of wide load - cost of scalar loads.
int ScalarLdCost = VecTy->getNumElements() *
TTI->getMemoryOpCost(Instruction::Load, ScalarTy, 1, 0);
int VecLdCost = TTI->getMemoryOpCost(Instruction::Load, ScalarTy, 1, 0);
return VecLdCost - ScalarLdCost;
}
case Instruction::Store: {
// We know that we can merge the stores. Calculate the cost.
int ScalarStCost = VecTy->getNumElements() *
TTI->getMemoryOpCost(Instruction::Store, ScalarTy, 1, 0);
int VecStCost = TTI->getMemoryOpCost(Instruction::Store, ScalarTy, 1, 0);
return VecStCost - ScalarStCost;
}
default:
llvm_unreachable("Unknown instruction");
}
}
int BoUpSLP::getTreeCost() {
int Cost = 0;
DEBUG(dbgs() << "SLP: Calculating cost for tree of size " <<
VectorizableTree.size() << ".\n");
// Don't vectorize tiny trees. Small load/store chains or consecutive stores
// of constants will be vectoried in SelectionDAG in MergeConsecutiveStores.
// The SelectionDAG vectorizer can only handle pairs (trees of height = 2).
if (VectorizableTree.size() < 3) {
if (!VectorizableTree.size()) {
assert(!ExternalUses.size() && "We should not have any external users");
}
return INT_MAX;
}
unsigned BundleWidth = VectorizableTree[0].Scalars.size();
for (unsigned i = 0, e = VectorizableTree.size(); i != e; ++i) {
int C = getEntryCost(&VectorizableTree[i]);
DEBUG(dbgs() << "SLP: Adding cost " << C << " for bundle that starts with "
<< *VectorizableTree[i].Scalars[0] << " .\n");
Cost += C;
}
int ExtractCost = 0;
for (UserList::iterator I = ExternalUses.begin(), E = ExternalUses.end();
I != E; ++I) {
VectorType *VecTy = VectorType::get(I->Scalar->getType(), BundleWidth);
ExtractCost += TTI->getVectorInstrCost(Instruction::ExtractElement, VecTy,
I->Lane);
}
DEBUG(dbgs() << "SLP: Total Cost " << Cost + ExtractCost<< ".\n");
return Cost + ExtractCost;
}
int BoUpSLP::getGatherCost(Type *Ty) {
int Cost = 0;
for (unsigned i = 0, e = cast<VectorType>(Ty)->getNumElements(); i < e; ++i)
Cost += TTI->getVectorInstrCost(Instruction::InsertElement, Ty, i);
return Cost;
}
int BoUpSLP::getGatherCost(ArrayRef<Value *> VL) {
// Find the type of the operands in VL.
Type *ScalarTy = VL[0]->getType();
if (StoreInst *SI = dyn_cast<StoreInst>(VL[0]))
ScalarTy = SI->getValueOperand()->getType();
VectorType *VecTy = VectorType::get(ScalarTy, VL.size());
// Find the cost of inserting/extracting values from the vector.
return getGatherCost(VecTy);
}
AliasAnalysis::Location BoUpSLP::getLocation(Instruction *I) {
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return AA->getLocation(SI);
if (LoadInst *LI = dyn_cast<LoadInst>(I))
return AA->getLocation(LI);
return AliasAnalysis::Location();
}
Value *BoUpSLP::getPointerOperand(Value *I) {
if (LoadInst *LI = dyn_cast<LoadInst>(I))
return LI->getPointerOperand();
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return SI->getPointerOperand();
return 0;
}
unsigned BoUpSLP::getAddressSpaceOperand(Value *I) {
if (LoadInst *L = dyn_cast<LoadInst>(I))
return L->getPointerAddressSpace();
if (StoreInst *S = dyn_cast<StoreInst>(I))
return S->getPointerAddressSpace();
return -1;
}
bool BoUpSLP::isConsecutiveAccess(Value *A, Value *B) {
Value *PtrA = getPointerOperand(A);
Value *PtrB = getPointerOperand(B);
unsigned ASA = getAddressSpaceOperand(A);
unsigned ASB = getAddressSpaceOperand(B);
// Check that the address spaces match and that the pointers are valid.
if (!PtrA || !PtrB || (ASA != ASB))
return false;
// Make sure that A and B are different pointers of the same type.
if (PtrA == PtrB || PtrA->getType() != PtrB->getType())
return false;
unsigned PtrBitWidth = DL->getPointerSizeInBits(ASA);
Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
APInt Size(PtrBitWidth, DL->getTypeStoreSize(Ty));
APInt OffsetA(PtrBitWidth, 0), OffsetB(PtrBitWidth, 0);
PtrA = PtrA->stripAndAccumulateInBoundsConstantOffsets(*DL, OffsetA);
PtrB = PtrB->stripAndAccumulateInBoundsConstantOffsets(*DL, OffsetB);
APInt OffsetDelta = OffsetB - OffsetA;
// Check if they are based on the same pointer. That makes the offsets
// sufficient.
if (PtrA == PtrB)
return OffsetDelta == Size;
// Compute the necessary base pointer delta to have the necessary final delta
// equal to the size.
APInt BaseDelta = Size - OffsetDelta;
// Otherwise compute the distance with SCEV between the base pointers.
const SCEV *PtrSCEVA = SE->getSCEV(PtrA);
const SCEV *PtrSCEVB = SE->getSCEV(PtrB);
const SCEV *C = SE->getConstant(BaseDelta);
const SCEV *X = SE->getAddExpr(PtrSCEVA, C);
return X == PtrSCEVB;
}
Value *BoUpSLP::getSinkBarrier(Instruction *Src, Instruction *Dst) {
assert(Src->getParent() == Dst->getParent() && "Not the same BB");
BasicBlock::iterator I = Src, E = Dst;
/// Scan all of the instruction from SRC to DST and check if
/// the source may alias.
for (++I; I != E; ++I) {
// Ignore store instructions that are marked as 'ignore'.
if (MemBarrierIgnoreList.count(I))
continue;
if (Src->mayWriteToMemory()) /* Write */ {
if (!I->mayReadOrWriteMemory())
continue;
} else /* Read */ {
if (!I->mayWriteToMemory())
continue;
}
AliasAnalysis::Location A = getLocation(&*I);
AliasAnalysis::Location B = getLocation(Src);
if (!A.Ptr || !B.Ptr || AA->alias(A, B))
return I;
}
return 0;
}
int BoUpSLP::getLastIndex(ArrayRef<Value *> VL) {
BasicBlock *BB = cast<Instruction>(VL[0])->getParent();
assert(BB == getSameBlock(VL) && BlocksNumbers.count(BB) && "Invalid block");
BlockNumbering &BN = BlocksNumbers[BB];
int MaxIdx = BN.getIndex(BB->getFirstNonPHI());
for (unsigned i = 0, e = VL.size(); i < e; ++i)
MaxIdx = std::max(MaxIdx, BN.getIndex(cast<Instruction>(VL[i])));
return MaxIdx;
}
Instruction *BoUpSLP::getLastInstruction(ArrayRef<Value *> VL) {
BasicBlock *BB = cast<Instruction>(VL[0])->getParent();
assert(BB == getSameBlock(VL) && BlocksNumbers.count(BB) && "Invalid block");
BlockNumbering &BN = BlocksNumbers[BB];
int MaxIdx = BN.getIndex(cast<Instruction>(VL[0]));
for (unsigned i = 1, e = VL.size(); i < e; ++i)
MaxIdx = std::max(MaxIdx, BN.getIndex(cast<Instruction>(VL[i])));
Instruction *I = BN.getInstruction(MaxIdx);
assert(I && "bad location");
return I;
}
void BoUpSLP::setInsertPointAfterBundle(ArrayRef<Value *> VL) {
Instruction *VL0 = cast<Instruction>(VL[0]);
Instruction *LastInst = getLastInstruction(VL);
BasicBlock::iterator NextInst = LastInst;
++NextInst;
Builder.SetInsertPoint(VL0->getParent(), NextInst);
Builder.SetCurrentDebugLocation(VL0->getDebugLoc());
}
Value *BoUpSLP::Gather(ArrayRef<Value *> VL, VectorType *Ty) {
Value *Vec = UndefValue::get(Ty);
// Generate the 'InsertElement' instruction.
for (unsigned i = 0; i < Ty->getNumElements(); ++i) {
Vec = Builder.CreateInsertElement(Vec, VL[i], Builder.getInt32(i));
if (Instruction *Insrt = dyn_cast<Instruction>(Vec)) {
GatherSeq.insert(Insrt);
// Add to our 'need-to-extract' list.
if (ScalarToTreeEntry.count(VL[i])) {
int Idx = ScalarToTreeEntry[VL[i]];
TreeEntry *E = &VectorizableTree[Idx];
// Find which lane we need to extract.
int FoundLane = -1;
for (unsigned Lane = 0, LE = VL.size(); Lane != LE; ++Lane) {
// Is this the lane of the scalar that we are looking for ?
if (E->Scalars[Lane] == VL[i]) {
FoundLane = Lane;
break;
}
}
assert(FoundLane >= 0 && "Could not find the correct lane");
ExternalUses.push_back(ExternalUser(VL[i], Insrt, FoundLane));
}
}
}
return Vec;
}
Value *BoUpSLP::alreadyVectorized(ArrayRef<Value *> VL) const {
SmallDenseMap<Value*, int>::const_iterator Entry
= ScalarToTreeEntry.find(VL[0]);
if (Entry != ScalarToTreeEntry.end()) {
int Idx = Entry->second;
const TreeEntry *En = &VectorizableTree[Idx];
if (En->isSame(VL) && En->VectorizedValue)
return En->VectorizedValue;
}
return 0;
}
Value *BoUpSLP::vectorizeTree(ArrayRef<Value *> VL) {
if (ScalarToTreeEntry.count(VL[0])) {
int Idx = ScalarToTreeEntry[VL[0]];
TreeEntry *E = &VectorizableTree[Idx];
if (E->isSame(VL))
return vectorizeTree(E);
}
Type *ScalarTy = VL[0]->getType();
if (StoreInst *SI = dyn_cast<StoreInst>(VL[0]))
ScalarTy = SI->getValueOperand()->getType();
VectorType *VecTy = VectorType::get(ScalarTy, VL.size());
return Gather(VL, VecTy);
}
Value *BoUpSLP::vectorizeTree(TreeEntry *E) {
BuilderLocGuard Guard(Builder);
if (E->VectorizedValue) {
DEBUG(dbgs() << "SLP: Diamond merged for " << *E->Scalars[0] << ".\n");
return E->VectorizedValue;
}
Instruction *VL0 = cast<Instruction>(E->Scalars[0]);
Type *ScalarTy = VL0->getType();
if (StoreInst *SI = dyn_cast<StoreInst>(VL0))
ScalarTy = SI->getValueOperand()->getType();
VectorType *VecTy = VectorType::get(ScalarTy, E->Scalars.size());
if (E->NeedToGather) {
setInsertPointAfterBundle(E->Scalars);
return Gather(E->Scalars, VecTy);
}
unsigned Opcode = VL0->getOpcode();
assert(Opcode == getSameOpcode(E->Scalars) && "Invalid opcode");
switch (Opcode) {
case Instruction::PHI: {
PHINode *PH = dyn_cast<PHINode>(VL0);
Builder.SetInsertPoint(PH->getParent()->getFirstInsertionPt());
Builder.SetCurrentDebugLocation(PH->getDebugLoc());
PHINode *NewPhi = Builder.CreatePHI(VecTy, PH->getNumIncomingValues());
E->VectorizedValue = NewPhi;
// PHINodes may have multiple entries from the same block. We want to
// visit every block once.
SmallSet<BasicBlock*, 4> VisitedBBs;
for (unsigned i = 0, e = PH->getNumIncomingValues(); i < e; ++i) {
ValueList Operands;
BasicBlock *IBB = PH->getIncomingBlock(i);
if (!VisitedBBs.insert(IBB)) {
NewPhi->addIncoming(NewPhi->getIncomingValueForBlock(IBB), IBB);
continue;
}
// Prepare the operand vector.
for (unsigned j = 0; j < E->Scalars.size(); ++j)
Operands.push_back(cast<PHINode>(E->Scalars[j])->
getIncomingValueForBlock(IBB));
Builder.SetInsertPoint(IBB->getTerminator());
Builder.SetCurrentDebugLocation(PH->getDebugLoc());
Value *Vec = vectorizeTree(Operands);
NewPhi->addIncoming(Vec, IBB);
}
assert(NewPhi->getNumIncomingValues() == PH->getNumIncomingValues() &&
"Invalid number of incoming values");
return NewPhi;
}
case Instruction::ExtractElement: {
if (CanReuseExtract(E->Scalars)) {
Value *V = VL0->getOperand(0);
E->VectorizedValue = V;
return V;
}
return Gather(E->Scalars, VecTy);
}
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::FPExt:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::SIToFP:
case Instruction::UIToFP:
case Instruction::Trunc:
case Instruction::FPTrunc:
case Instruction::BitCast: {
ValueList INVL;
for (int i = 0, e = E->Scalars.size(); i < e; ++i)
INVL.push_back(cast<Instruction>(E->Scalars[i])->getOperand(0));
setInsertPointAfterBundle(E->Scalars);
Value *InVec = vectorizeTree(INVL);
if (Value *V = alreadyVectorized(E->Scalars))
return V;
CastInst *CI = dyn_cast<CastInst>(VL0);
Value *V = Builder.CreateCast(CI->getOpcode(), InVec, VecTy);
E->VectorizedValue = V;
return V;
}
case Instruction::FCmp:
case Instruction::ICmp: {
ValueList LHSV, RHSV;
for (int i = 0, e = E->Scalars.size(); i < e; ++i) {
LHSV.push_back(cast<Instruction>(E->Scalars[i])->getOperand(0));
RHSV.push_back(cast<Instruction>(E->Scalars[i])->getOperand(1));
}
setInsertPointAfterBundle(E->Scalars);
Value *L = vectorizeTree(LHSV);
Value *R = vectorizeTree(RHSV);
if (Value *V = alreadyVectorized(E->Scalars))
return V;
CmpInst::Predicate P0 = dyn_cast<CmpInst>(VL0)->getPredicate();
Value *V;
if (Opcode == Instruction::FCmp)
V = Builder.CreateFCmp(P0, L, R);
else
V = Builder.CreateICmp(P0, L, R);
E->VectorizedValue = V;
return V;
}
case Instruction::Select: {
ValueList TrueVec, FalseVec, CondVec;
for (int i = 0, e = E->Scalars.size(); i < e; ++i) {
CondVec.push_back(cast<Instruction>(E->Scalars[i])->getOperand(0));
TrueVec.push_back(cast<Instruction>(E->Scalars[i])->getOperand(1));
FalseVec.push_back(cast<Instruction>(E->Scalars[i])->getOperand(2));
}
setInsertPointAfterBundle(E->Scalars);
Value *Cond = vectorizeTree(CondVec);
Value *True = vectorizeTree(TrueVec);
Value *False = vectorizeTree(FalseVec);
if (Value *V = alreadyVectorized(E->Scalars))
return V;
Value *V = Builder.CreateSelect(Cond, True, False);
E->VectorizedValue = V;
return V;
}
case Instruction::Add:
case Instruction::FAdd:
case Instruction::Sub:
case Instruction::FSub:
case Instruction::Mul:
case Instruction::FMul:
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::FDiv:
case Instruction::URem:
case Instruction::SRem:
case Instruction::FRem:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor: {
ValueList LHSVL, RHSVL;
for (int i = 0, e = E->Scalars.size(); i < e; ++i) {
LHSVL.push_back(cast<Instruction>(E->Scalars[i])->getOperand(0));
RHSVL.push_back(cast<Instruction>(E->Scalars[i])->getOperand(1));
}
setInsertPointAfterBundle(E->Scalars);
Value *LHS = vectorizeTree(LHSVL);
Value *RHS = vectorizeTree(RHSVL);
if (LHS == RHS && isa<Instruction>(LHS)) {
assert((VL0->getOperand(0) == VL0->getOperand(1)) && "Invalid order");
}
if (Value *V = alreadyVectorized(E->Scalars))
return V;
BinaryOperator *BinOp = cast<BinaryOperator>(VL0);
Value *V = Builder.CreateBinOp(BinOp->getOpcode(), LHS, RHS);
E->VectorizedValue = V;
return V;
}
case Instruction::Load: {
// Loads are inserted at the head of the tree because we don't want to
// sink them all the way down past store instructions.
setInsertPointAfterBundle(E->Scalars);
LoadInst *LI = cast<LoadInst>(VL0);
Value *VecPtr =
Builder.CreateBitCast(LI->getPointerOperand(), VecTy->getPointerTo());
unsigned Alignment = LI->getAlignment();
LI = Builder.CreateLoad(VecPtr);
LI->setAlignment(Alignment);
E->VectorizedValue = LI;
return LI;
}
case Instruction::Store: {
StoreInst *SI = cast<StoreInst>(VL0);
unsigned Alignment = SI->getAlignment();
ValueList ValueOp;
for (int i = 0, e = E->Scalars.size(); i < e; ++i)
ValueOp.push_back(cast<StoreInst>(E->Scalars[i])->getValueOperand());
setInsertPointAfterBundle(E->Scalars);
Value *VecValue = vectorizeTree(ValueOp);
Value *VecPtr =
Builder.CreateBitCast(SI->getPointerOperand(), VecTy->getPointerTo());
StoreInst *S = Builder.CreateStore(VecValue, VecPtr);
S->setAlignment(Alignment);
E->VectorizedValue = S;
return S;
}
default:
llvm_unreachable("unknown inst");
}
return 0;
}
Value *BoUpSLP::vectorizeTree() {
Builder.SetInsertPoint(F->getEntryBlock().begin());
vectorizeTree(&VectorizableTree[0]);
DEBUG(dbgs() << "SLP: Extracting " << ExternalUses.size() << " values .\n");
// Extract all of the elements with the external uses.
for (UserList::iterator it = ExternalUses.begin(), e = ExternalUses.end();
it != e; ++it) {
Value *Scalar = it->Scalar;
llvm::User *User = it->User;
// Skip users that we already RAUW. This happens when one instruction
// has multiple uses of the same value.
if (std::find(Scalar->use_begin(), Scalar->use_end(), User) ==
Scalar->use_end())
continue;
assert(ScalarToTreeEntry.count(Scalar) && "Invalid scalar");
int Idx = ScalarToTreeEntry[Scalar];
TreeEntry *E = &VectorizableTree[Idx];
assert(!E->NeedToGather && "Extracting from a gather list");
Value *Vec = E->VectorizedValue;
assert(Vec && "Can't find vectorizable value");
Value *Lane = Builder.getInt32(it->Lane);
// Generate extracts for out-of-tree users.
// Find the insertion point for the extractelement lane.
if (PHINode *PN = dyn_cast<PHINode>(Vec)) {
Builder.SetInsertPoint(PN->getParent()->getFirstInsertionPt());
Value *Ex = Builder.CreateExtractElement(Vec, Lane);
User->replaceUsesOfWith(Scalar, Ex);
} else if (isa<Instruction>(Vec)){
if (PHINode *PH = dyn_cast<PHINode>(User)) {
for (int i = 0, e = PH->getNumIncomingValues(); i != e; ++i) {
if (PH->getIncomingValue(i) == Scalar) {
Builder.SetInsertPoint(PH->getIncomingBlock(i)->getTerminator());
Value *Ex = Builder.CreateExtractElement(Vec, Lane);
PH->setOperand(i, Ex);
}
}
} else {
Builder.SetInsertPoint(cast<Instruction>(User));
Value *Ex = Builder.CreateExtractElement(Vec, Lane);
User->replaceUsesOfWith(Scalar, Ex);
}
} else {
Builder.SetInsertPoint(F->getEntryBlock().begin());
Value *Ex = Builder.CreateExtractElement(Vec, Lane);
User->replaceUsesOfWith(Scalar, Ex);
}
DEBUG(dbgs() << "SLP: Replaced:" << *User << ".\n");
}
// For each vectorized value:
for (int EIdx = 0, EE = VectorizableTree.size(); EIdx < EE; ++EIdx) {
TreeEntry *Entry = &VectorizableTree[EIdx];
// For each lane:
for (int Lane = 0, LE = Entry->Scalars.size(); Lane != LE; ++Lane) {
Value *Scalar = Entry->Scalars[Lane];
// No need to handle users of gathered values.
if (Entry->NeedToGather)
continue;
assert(Entry->VectorizedValue && "Can't find vectorizable value");
Type *Ty = Scalar->getType();
if (!Ty->isVoidTy()) {
for (Value::use_iterator User = Scalar->use_begin(),
UE = Scalar->use_end(); User != UE; ++User) {
DEBUG(dbgs() << "SLP: \tvalidating user:" << **User << ".\n");
assert(!MustGather.count(*User) &&
"Replacing gathered value with undef");
assert((ScalarToTreeEntry.count(*User) ||
// It is legal to replace the reduction users by undef.
(RdxOps && RdxOps->count(*User))) &&
"Replacing out-of-tree value with undef");
}
Value *Undef = UndefValue::get(Ty);
Scalar->replaceAllUsesWith(Undef);
}
DEBUG(dbgs() << "SLP: \tErasing scalar:" << *Scalar << ".\n");
cast<Instruction>(Scalar)->eraseFromParent();
}
}
for (Function::iterator it = F->begin(), e = F->end(); it != e; ++it) {
BlocksNumbers[it].forget();
}
Builder.ClearInsertionPoint();
return VectorizableTree[0].VectorizedValue;
}
void BoUpSLP::optimizeGatherSequence() {
DEBUG(dbgs() << "SLP: Optimizing " << GatherSeq.size()
<< " gather sequences instructions.\n");
// LICM InsertElementInst sequences.
for (SetVector<Instruction *>::iterator it = GatherSeq.begin(),
e = GatherSeq.end(); it != e; ++it) {
InsertElementInst *Insert = dyn_cast<InsertElementInst>(*it);
if (!Insert)
continue;
// Check if this block is inside a loop.
Loop *L = LI->getLoopFor(Insert->getParent());
if (!L)
continue;
// Check if it has a preheader.
BasicBlock *PreHeader = L->getLoopPreheader();
if (!PreHeader)
continue;
// If the vector or the element that we insert into it are
// instructions that are defined in this basic block then we can't
// hoist this instruction.
Instruction *CurrVec = dyn_cast<Instruction>(Insert->getOperand(0));
Instruction *NewElem = dyn_cast<Instruction>(Insert->getOperand(1));
if (CurrVec && L->contains(CurrVec))
continue;
if (NewElem && L->contains(NewElem))
continue;
// We can hoist this instruction. Move it to the pre-header.
Insert->moveBefore(PreHeader->getTerminator());
}
// Perform O(N^2) search over the gather sequences and merge identical
// instructions. TODO: We can further optimize this scan if we split the
// instructions into different buckets based on the insert lane.
SmallPtrSet<Instruction*, 16> Visited;
SmallVector<Instruction*, 16> ToRemove;
ReversePostOrderTraversal<Function*> RPOT(F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
E = RPOT.end(); I != E; ++I) {
BasicBlock *BB = *I;
// For all instructions in the function:
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
Instruction *In = it;
if ((!isa<InsertElementInst>(In) && !isa<ExtractElementInst>(In)) ||
!GatherSeq.count(In))
continue;
// Check if we can replace this instruction with any of the
// visited instructions.
for (SmallPtrSet<Instruction*, 16>::iterator v = Visited.begin(),
ve = Visited.end(); v != ve; ++v) {
if (In->isIdenticalTo(*v) &&
DT->dominates((*v)->getParent(), In->getParent())) {
In->replaceAllUsesWith(*v);
ToRemove.push_back(In);
In = 0;
break;
}
}
if (In)
Visited.insert(In);
}
}
// Erase all of the instructions that we RAUWed.
for (SmallVectorImpl<Instruction *>::iterator v = ToRemove.begin(),
ve = ToRemove.end(); v != ve; ++v) {
assert((*v)->getNumUses() == 0 && "Can't remove instructions with uses");
(*v)->eraseFromParent();
}
}
/// The SLPVectorizer Pass.
struct SLPVectorizer : public FunctionPass {
typedef SmallVector<StoreInst *, 8> StoreList;
typedef MapVector<Value *, StoreList> StoreListMap;
/// Pass identification, replacement for typeid
static char ID;
explicit SLPVectorizer() : FunctionPass(ID) {
initializeSLPVectorizerPass(*PassRegistry::getPassRegistry());
}
ScalarEvolution *SE;
DataLayout *DL;
TargetTransformInfo *TTI;
AliasAnalysis *AA;
LoopInfo *LI;
DominatorTree *DT;
virtual bool runOnFunction(Function &F) {
SE = &getAnalysis<ScalarEvolution>();
DL = getAnalysisIfAvailable<DataLayout>();
TTI = &getAnalysis<TargetTransformInfo>();
AA = &getAnalysis<AliasAnalysis>();
LI = &getAnalysis<LoopInfo>();
DT = &getAnalysis<DominatorTree>();
StoreRefs.clear();
bool Changed = false;
// If the target claims to have no vector registers don't attempt
// vectorization.
if (!TTI->getNumberOfRegisters(true))
return false;
// Must have DataLayout. We can't require it because some tests run w/o
// triple.
if (!DL)
return false;
// Don't vectorize when the attribute NoImplicitFloat is used.
if (F.hasFnAttribute(Attribute::NoImplicitFloat))
return false;
DEBUG(dbgs() << "SLP: Analyzing blocks in " << F.getName() << ".\n");
// Use the bollom up slp vectorizer to construct chains that start with
// he store instructions.
BoUpSLP R(&F, SE, DL, TTI, AA, LI, DT);
// Scan the blocks in the function in post order.
for (po_iterator<BasicBlock*> it = po_begin(&F.getEntryBlock()),
e = po_end(&F.getEntryBlock()); it != e; ++it) {
BasicBlock *BB = *it;
// Vectorize trees that end at stores.
if (unsigned count = collectStores(BB, R)) {
(void)count;
DEBUG(dbgs() << "SLP: Found " << count << " stores to vectorize.\n");
Changed |= vectorizeStoreChains(R);
}
// Vectorize trees that end at reductions.
Changed |= vectorizeChainsInBlock(BB, R);
}
if (Changed) {
R.optimizeGatherSequence();
DEBUG(dbgs() << "SLP: vectorized \"" << F.getName() << "\"\n");
DEBUG(verifyFunction(F));
}
return Changed;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
FunctionPass::getAnalysisUsage(AU);
AU.addRequired<ScalarEvolution>();
AU.addRequired<AliasAnalysis>();
AU.addRequired<TargetTransformInfo>();
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorTree>();
AU.addPreserved<LoopInfo>();
AU.addPreserved<DominatorTree>();
AU.setPreservesCFG();
}
private:
/// \brief Collect memory references and sort them according to their base
/// object. We sort the stores to their base objects to reduce the cost of the
/// quadratic search on the stores. TODO: We can further reduce this cost
/// if we flush the chain creation every time we run into a memory barrier.
unsigned collectStores(BasicBlock *BB, BoUpSLP &R);
/// \brief Try to vectorize a chain that starts at two arithmetic instrs.
bool tryToVectorizePair(Value *A, Value *B, BoUpSLP &R);
/// \brief Try to vectorize a list of operands.
/// \returns true if a value was vectorized.
bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R);
/// \brief Try to vectorize a chain that may start at the operands of \V;
bool tryToVectorize(BinaryOperator *V, BoUpSLP &R);
/// \brief Vectorize the stores that were collected in StoreRefs.
bool vectorizeStoreChains(BoUpSLP &R);
/// \brief Scan the basic block and look for patterns that are likely to start
/// a vectorization chain.
bool vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R);
bool vectorizeStoreChain(ArrayRef<Value *> Chain, int CostThreshold,
BoUpSLP &R);
bool vectorizeStores(ArrayRef<StoreInst *> Stores, int costThreshold,
BoUpSLP &R);
private:
StoreListMap StoreRefs;
};
bool SLPVectorizer::vectorizeStoreChain(ArrayRef<Value *> Chain,
int CostThreshold, BoUpSLP &R) {
unsigned ChainLen = Chain.size();
DEBUG(dbgs() << "SLP: Analyzing a store chain of length " << ChainLen
<< "\n");
Type *StoreTy = cast<StoreInst>(Chain[0])->getValueOperand()->getType();
unsigned Sz = DL->getTypeSizeInBits(StoreTy);
unsigned VF = MinVecRegSize / Sz;
if (!isPowerOf2_32(Sz) || VF < 2)
return false;
bool Changed = false;
// Look for profitable vectorizable trees at all offsets, starting at zero.
for (unsigned i = 0, e = ChainLen; i < e; ++i) {
if (i + VF > e)
break;
DEBUG(dbgs() << "SLP: Analyzing " << VF << " stores at offset " << i
<< "\n");
ArrayRef<Value *> Operands = Chain.slice(i, VF);
R.buildTree(Operands);
int Cost = R.getTreeCost();
DEBUG(dbgs() << "SLP: Found cost=" << Cost << " for VF=" << VF << "\n");
if (Cost < CostThreshold) {
DEBUG(dbgs() << "SLP: Decided to vectorize cost=" << Cost << "\n");
R.vectorizeTree();
// Move to the next bundle.
i += VF - 1;
Changed = true;
}
}
return Changed;
}
bool SLPVectorizer::vectorizeStores(ArrayRef<StoreInst *> Stores,
int costThreshold, BoUpSLP &R) {
SetVector<Value *> Heads, Tails;
SmallDenseMap<Value *, Value *> ConsecutiveChain;
// We may run into multiple chains that merge into a single chain. We mark the
// stores that we vectorized so that we don't visit the same store twice.
BoUpSLP::ValueSet VectorizedStores;
bool Changed = false;
// Do a quadratic search on all of the given stores and find
// all of the pairs of stores that follow each other.
for (unsigned i = 0, e = Stores.size(); i < e; ++i) {
for (unsigned j = 0; j < e; ++j) {
if (i == j)
continue;
if (R.isConsecutiveAccess(Stores[i], Stores[j])) {
Tails.insert(Stores[j]);
Heads.insert(Stores[i]);
ConsecutiveChain[Stores[i]] = Stores[j];
}
}
}
// For stores that start but don't end a link in the chain:
for (SetVector<Value *>::iterator it = Heads.begin(), e = Heads.end();
it != e; ++it) {
if (Tails.count(*it))
continue;
// We found a store instr that starts a chain. Now follow the chain and try
// to vectorize it.
BoUpSLP::ValueList Operands;
Value *I = *it;
// Collect the chain into a list.
while (Tails.count(I) || Heads.count(I)) {
if (VectorizedStores.count(I))
break;
Operands.push_back(I);
// Move to the next value in the chain.
I = ConsecutiveChain[I];
}
bool Vectorized = vectorizeStoreChain(Operands, costThreshold, R);
// Mark the vectorized stores so that we don't vectorize them again.
if (Vectorized)
VectorizedStores.insert(Operands.begin(), Operands.end());
Changed |= Vectorized;
}
return Changed;
}
unsigned SLPVectorizer::collectStores(BasicBlock *BB, BoUpSLP &R) {
unsigned count = 0;
StoreRefs.clear();
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
StoreInst *SI = dyn_cast<StoreInst>(it);
if (!SI)
continue;
// Check that the pointer points to scalars.
Type *Ty = SI->getValueOperand()->getType();
if (Ty->isAggregateType() || Ty->isVectorTy())
return 0;
// Find the base of the GEP.
Value *Ptr = SI->getPointerOperand();
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
Ptr = GEP->getPointerOperand();
// Save the store locations.
StoreRefs[Ptr].push_back(SI);
count++;
}
return count;
}
bool SLPVectorizer::tryToVectorizePair(Value *A, Value *B, BoUpSLP &R) {
if (!A || !B)
return false;
Value *VL[] = { A, B };
return tryToVectorizeList(VL, R);
}
bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R) {
if (VL.size() < 2)
return false;
DEBUG(dbgs() << "SLP: Vectorizing a list of length = " << VL.size() << ".\n");
// Check that all of the parts are scalar instructions of the same type.
Instruction *I0 = dyn_cast<Instruction>(VL[0]);
if (!I0)
return false;
unsigned Opcode0 = I0->getOpcode();
Type *Ty0 = I0->getType();
unsigned Sz = DL->getTypeSizeInBits(Ty0);
unsigned VF = MinVecRegSize / Sz;
for (int i = 0, e = VL.size(); i < e; ++i) {
Type *Ty = VL[i]->getType();
if (Ty->isAggregateType() || Ty->isVectorTy())
return false;
Instruction *Inst = dyn_cast<Instruction>(VL[i]);
if (!Inst || Inst->getOpcode() != Opcode0)
return false;
}
bool Changed = false;
for (unsigned i = 0, e = VL.size(); i < e; ++i) {
unsigned OpsWidth = 0;
if (i + VF > e)
OpsWidth = e - i;
else
OpsWidth = VF;
if (!isPowerOf2_32(OpsWidth) || OpsWidth < 2)
break;
DEBUG(dbgs() << "SLP: Analyzing " << OpsWidth << " operations " << "\n");
ArrayRef<Value *> Ops = VL.slice(i, OpsWidth);
R.buildTree(Ops);
int Cost = R.getTreeCost();
if (Cost < -SLPCostThreshold) {
DEBUG(dbgs() << "SLP: Vectorizing pair at cost:" << Cost << ".\n");
R.vectorizeTree();
// Move to the next bundle.
i += VF - 1;
Changed = true;
}
}
return Changed;
}
bool SLPVectorizer::tryToVectorize(BinaryOperator *V, BoUpSLP &R) {
if (!V)
return false;
// Try to vectorize V.
if (tryToVectorizePair(V->getOperand(0), V->getOperand(1), R))
return true;
BinaryOperator *A = dyn_cast<BinaryOperator>(V->getOperand(0));
BinaryOperator *B = dyn_cast<BinaryOperator>(V->getOperand(1));
// Try to skip B.
if (B && B->hasOneUse()) {
BinaryOperator *B0 = dyn_cast<BinaryOperator>(B->getOperand(0));
BinaryOperator *B1 = dyn_cast<BinaryOperator>(B->getOperand(1));
if (tryToVectorizePair(A, B0, R)) {
B->moveBefore(V);
return true;
}
if (tryToVectorizePair(A, B1, R)) {
B->moveBefore(V);
return true;
}
}
// Try to skip A.
if (A && A->hasOneUse()) {
BinaryOperator *A0 = dyn_cast<BinaryOperator>(A->getOperand(0));
BinaryOperator *A1 = dyn_cast<BinaryOperator>(A->getOperand(1));
if (tryToVectorizePair(A0, B, R)) {
A->moveBefore(V);
return true;
}
if (tryToVectorizePair(A1, B, R)) {
A->moveBefore(V);
return true;
}
}
return 0;
}
/// \brief Generate a shuffle mask to be used in a reduction tree.
///
/// \param VecLen The length of the vector to be reduced.
/// \param NumEltsToRdx The number of elements that should be reduced in the
/// vector.
/// \param IsPairwise Whether the reduction is a pairwise or splitting
/// reduction. A pairwise reduction will generate a mask of
/// <0,2,...> or <1,3,..> while a splitting reduction will generate
/// <2,3, undef,undef> for a vector of 4 and NumElts = 2.
/// \param IsLeft True will generate a mask of even elements, odd otherwise.
static Value *createRdxShuffleMask(unsigned VecLen, unsigned NumEltsToRdx,
bool IsPairwise, bool IsLeft,
IRBuilder<> &Builder) {
assert((IsPairwise || !IsLeft) && "Don't support a <0,1,undef,...> mask");
SmallVector<Constant *, 32> ShuffleMask(
VecLen, UndefValue::get(Builder.getInt32Ty()));
if (IsPairwise)
// Build a mask of 0, 2, ... (left) or 1, 3, ... (right).
for (unsigned i = 0; i != NumEltsToRdx; ++i)
ShuffleMask[i] = Builder.getInt32(2 * i + !IsLeft);
else
// Move the upper half of the vector to the lower half.
for (unsigned i = 0; i != NumEltsToRdx; ++i)
ShuffleMask[i] = Builder.getInt32(NumEltsToRdx + i);
return ConstantVector::get(ShuffleMask);
}
/// Model horizontal reductions.
///
/// A horizontal reduction is a tree of reduction operations (currently add and
/// fadd) that has operations that can be put into a vector as its leaf.
/// For example, this tree:
///
/// mul mul mul mul
/// \ / \ /
/// + +
/// \ /
/// +
/// This tree has "mul" as its reduced values and "+" as its reduction
/// operations. A reduction might be feeding into a store or a binary operation
/// feeding a phi.
/// ...
/// \ /
/// +
/// |
/// phi +=
///
/// Or:
/// ...
/// \ /
/// +
/// |
/// *p =
///
class HorizontalReduction {
SmallPtrSet<Value *, 16> ReductionOps;
SmallVector<Value *, 32> ReducedVals;
BinaryOperator *ReductionRoot;
PHINode *ReductionPHI;
/// The opcode of the reduction.
unsigned ReductionOpcode;
/// The opcode of the values we perform a reduction on.
unsigned ReducedValueOpcode;
/// The width of one full horizontal reduction operation.
unsigned ReduxWidth;
/// Should we model this reduction as a pairwise reduction tree or a tree that
/// splits the vector in halves and adds those halves.
bool IsPairwiseReduction;
public:
HorizontalReduction()
: ReductionRoot(0), ReductionPHI(0), ReductionOpcode(0),
ReducedValueOpcode(0), ReduxWidth(0), IsPairwiseReduction(false) {}
/// \brief Try to find a reduction tree.
bool matchAssociativeReduction(PHINode *Phi, BinaryOperator *B,
DataLayout *DL) {
assert((!Phi ||
std::find(Phi->op_begin(), Phi->op_end(), B) != Phi->op_end()) &&
"Thi phi needs to use the binary operator");
// We could have a initial reductions that is not an add.
// r *= v1 + v2 + v3 + v4
// In such a case start looking for a tree rooted in the first '+'.
if (Phi) {
if (B->getOperand(0) == Phi) {
Phi = 0;
B = dyn_cast<BinaryOperator>(B->getOperand(1));
} else if (B->getOperand(1) == Phi) {
Phi = 0;
B = dyn_cast<BinaryOperator>(B->getOperand(0));
}
}
if (!B)
return false;
Type *Ty = B->getType();
if (Ty->isVectorTy())
return false;
ReductionOpcode = B->getOpcode();
ReducedValueOpcode = 0;
ReduxWidth = MinVecRegSize / DL->getTypeSizeInBits(Ty);
ReductionRoot = B;
ReductionPHI = Phi;
if (ReduxWidth < 4)
return false;
// We currently only support adds.
if (ReductionOpcode != Instruction::Add &&
ReductionOpcode != Instruction::FAdd)
return false;
// Post order traverse the reduction tree starting at B. We only handle true
// trees containing only binary operators.
SmallVector<std::pair<BinaryOperator *, unsigned>, 32> Stack;
Stack.push_back(std::make_pair(B, 0));
while (!Stack.empty()) {
BinaryOperator *TreeN = Stack.back().first;
unsigned EdgeToVist = Stack.back().second++;
bool IsReducedValue = TreeN->getOpcode() != ReductionOpcode;
// Only handle trees in the current basic block.
if (TreeN->getParent() != B->getParent())
return false;
// Each tree node needs to have one user except for the ultimate
// reduction.
if (!TreeN->hasOneUse() && TreeN != B)
return false;
// Postorder vist.
if (EdgeToVist == 2 || IsReducedValue) {
if (IsReducedValue) {
// Make sure that the opcodes of the operations that we are going to
// reduce match.
if (!ReducedValueOpcode)
ReducedValueOpcode = TreeN->getOpcode();
else if (ReducedValueOpcode != TreeN->getOpcode())
return false;
ReducedVals.push_back(TreeN);
} else {
// We need to be able to reassociate the adds.
if (!TreeN->isAssociative())
return false;
ReductionOps.insert(TreeN);
}
// Retract.
Stack.pop_back();
continue;
}
// Visit left or right.
Value *NextV = TreeN->getOperand(EdgeToVist);
BinaryOperator *Next = dyn_cast<BinaryOperator>(NextV);
if (Next)
Stack.push_back(std::make_pair(Next, 0));
else if (NextV != Phi)
return false;
}
return true;
}
/// \brief Attempt to vectorize the tree found by
/// matchAssociativeReduction.
bool tryToReduce(BoUpSLP &V, TargetTransformInfo *TTI) {
if (ReducedVals.empty())
return false;
unsigned NumReducedVals = ReducedVals.size();
if (NumReducedVals < ReduxWidth)
return false;
Value *VectorizedTree = 0;
IRBuilder<> Builder(ReductionRoot);
FastMathFlags Unsafe;
Unsafe.setUnsafeAlgebra();
Builder.SetFastMathFlags(Unsafe);
unsigned i = 0;
for (; i < NumReducedVals - ReduxWidth + 1; i += ReduxWidth) {
ArrayRef<Value *> ValsToReduce(&ReducedVals[i], ReduxWidth);
V.buildTree(ValsToReduce, &ReductionOps);
// Estimate cost.
int Cost = V.getTreeCost() + getReductionCost(TTI, ReducedVals[i]);
if (Cost >= -SLPCostThreshold)
break;
DEBUG(dbgs() << "SLP: Vectorizing horizontal reduction at cost:" << Cost
<< ". (HorRdx)\n");
// Vectorize a tree.
DebugLoc Loc = cast<Instruction>(ReducedVals[i])->getDebugLoc();
Value *VectorizedRoot = V.vectorizeTree();
// Emit a reduction.
Value *ReducedSubTree = emitReduction(VectorizedRoot, Builder);
if (VectorizedTree) {
Builder.SetCurrentDebugLocation(Loc);
VectorizedTree = createBinOp(Builder, ReductionOpcode, VectorizedTree,
ReducedSubTree, "bin.rdx");
} else
VectorizedTree = ReducedSubTree;
}
if (VectorizedTree) {
// Finish the reduction.
for (; i < NumReducedVals; ++i) {
Builder.SetCurrentDebugLocation(
cast<Instruction>(ReducedVals[i])->getDebugLoc());
VectorizedTree = createBinOp(Builder, ReductionOpcode, VectorizedTree,
ReducedVals[i]);
}
// Update users.
if (ReductionPHI) {
assert(ReductionRoot != NULL && "Need a reduction operation");
ReductionRoot->setOperand(0, VectorizedTree);
ReductionRoot->setOperand(1, ReductionPHI);
} else
ReductionRoot->replaceAllUsesWith(VectorizedTree);
}
return VectorizedTree != 0;
}
private:
/// \brief Calcuate the cost of a reduction.
int getReductionCost(TargetTransformInfo *TTI, Value *FirstReducedVal) {
Type *ScalarTy = FirstReducedVal->getType();
Type *VecTy = VectorType::get(ScalarTy, ReduxWidth);
int PairwiseRdxCost = TTI->getReductionCost(ReductionOpcode, VecTy, true);
int SplittingRdxCost = TTI->getReductionCost(ReductionOpcode, VecTy, false);
IsPairwiseReduction = PairwiseRdxCost < SplittingRdxCost;
int VecReduxCost = IsPairwiseReduction ? PairwiseRdxCost : SplittingRdxCost;
int ScalarReduxCost =
ReduxWidth * TTI->getArithmeticInstrCost(ReductionOpcode, VecTy);
DEBUG(dbgs() << "SLP: Adding cost " << VecReduxCost - ScalarReduxCost
<< " for reduction that starts with " << *FirstReducedVal
<< " (It is a "
<< (IsPairwiseReduction ? "pairwise" : "splitting")
<< " reduction)\n");
return VecReduxCost - ScalarReduxCost;
}
static Value *createBinOp(IRBuilder<> &Builder, unsigned Opcode, Value *L,
Value *R, const Twine &Name = "") {
if (Opcode == Instruction::FAdd)
return Builder.CreateFAdd(L, R, Name);
return Builder.CreateBinOp((Instruction::BinaryOps)Opcode, L, R, Name);
}
/// \brief Emit a horizontal reduction of the vectorized value.
Value *emitReduction(Value *VectorizedValue, IRBuilder<> &Builder) {
assert(VectorizedValue && "Need to have a vectorized tree node");
Instruction *ValToReduce = dyn_cast<Instruction>(VectorizedValue);
assert(isPowerOf2_32(ReduxWidth) &&
"We only handle power-of-two reductions for now");
SmallVector<Constant *, 32> ShuffleMask(ReduxWidth, 0);
Value *TmpVec = ValToReduce;
for (unsigned i = ReduxWidth / 2; i != 0; i >>= 1) {
if (IsPairwiseReduction) {
Value *LeftMask =
createRdxShuffleMask(ReduxWidth, i, true, true, Builder);
Value *RightMask =
createRdxShuffleMask(ReduxWidth, i, true, false, Builder);
Value *LeftShuf = Builder.CreateShuffleVector(
TmpVec, UndefValue::get(TmpVec->getType()), LeftMask, "rdx.shuf.l");
Value *RightShuf = Builder.CreateShuffleVector(
TmpVec, UndefValue::get(TmpVec->getType()), (RightMask),
"rdx.shuf.r");
TmpVec = createBinOp(Builder, ReductionOpcode, LeftShuf, RightShuf,
"bin.rdx");
} else {
Value *UpperHalf =
createRdxShuffleMask(ReduxWidth, i, false, false, Builder);
Value *Shuf = Builder.CreateShuffleVector(
TmpVec, UndefValue::get(TmpVec->getType()), UpperHalf, "rdx.shuf");
TmpVec = createBinOp(Builder, ReductionOpcode, TmpVec, Shuf, "bin.rdx");
}
}
// The result is in the first element of the vector.
return Builder.CreateExtractElement(TmpVec, Builder.getInt32(0));
}
};
/// \brief Recognize construction of vectors like
/// %ra = insertelement <4 x float> undef, float %s0, i32 0
/// %rb = insertelement <4 x float> %ra, float %s1, i32 1
/// %rc = insertelement <4 x float> %rb, float %s2, i32 2
/// %rd = insertelement <4 x float> %rc, float %s3, i32 3
///
/// Returns true if it matches
///
static bool findBuildVector(InsertElementInst *IE,
SmallVectorImpl<Value *> &Ops) {
if (!isa<UndefValue>(IE->getOperand(0)))
return false;
while (true) {
Ops.push_back(IE->getOperand(1));
if (IE->use_empty())
return false;
InsertElementInst *NextUse = dyn_cast<InsertElementInst>(IE->use_back());
if (!NextUse)
return true;
// If this isn't the final use, make sure the next insertelement is the only
// use. It's OK if the final constructed vector is used multiple times
if (!IE->hasOneUse())
return false;
IE = NextUse;
}
return false;
}
bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
bool Changed = false;
SmallVector<Value *, 4> Incoming;
SmallSet<Instruction *, 16> VisitedInstrs;
// Collect the incoming values from the PHIs.
for (BasicBlock::iterator instr = BB->begin(), ie = BB->end(); instr != ie;
++instr) {
PHINode *P = dyn_cast<PHINode>(instr);
if (!P)
break;
// We may go through BB multiple times so skip the one we have checked.
if (!VisitedInstrs.insert(instr))
continue;
// Stop constructing the list when you reach a different type.
if (Incoming.size() && P->getType() != Incoming[0]->getType()) {
if (tryToVectorizeList(Incoming, R)) {
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
Changed = true;
instr = BB->begin();
ie = BB->end();
}
Incoming.clear();
}
Incoming.push_back(P);
}
if (Incoming.size() > 1)
Changed |= tryToVectorizeList(Incoming, R);
VisitedInstrs.clear();
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; it++) {
// We may go through BB multiple times so skip the one we have checked.
if (!VisitedInstrs.insert(it))
continue;
if (isa<DbgInfoIntrinsic>(it))
continue;
// Try to vectorize reductions that use PHINodes.
if (PHINode *P = dyn_cast<PHINode>(it)) {
// Check that the PHI is a reduction PHI.
if (P->getNumIncomingValues() != 2)
return Changed;
Value *Rdx =
(P->getIncomingBlock(0) == BB
? (P->getIncomingValue(0))
: (P->getIncomingBlock(1) == BB ? P->getIncomingValue(1) : 0));
// Check if this is a Binary Operator.
BinaryOperator *BI = dyn_cast_or_null<BinaryOperator>(Rdx);
if (!BI)
continue;
// Try to match and vectorize a horizontal reduction.
HorizontalReduction HorRdx;
if (ShouldVectorizeHor &&
HorRdx.matchAssociativeReduction(P, BI, DL) &&
HorRdx.tryToReduce(R, TTI)) {
Changed = true;
it = BB->begin();
e = BB->end();
continue;
}
Value *Inst = BI->getOperand(0);
if (Inst == P)
Inst = BI->getOperand(1);
if (tryToVectorize(dyn_cast<BinaryOperator>(Inst), R)) {
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
Changed = true;
it = BB->begin();
e = BB->end();
continue;
}
continue;
}
// Try to vectorize horizontal reductions feeding into a store.
if (ShouldStartVectorizeHorAtStore)
if (StoreInst *SI = dyn_cast<StoreInst>(it))
if (BinaryOperator *BinOp =
dyn_cast<BinaryOperator>(SI->getValueOperand())) {
HorizontalReduction HorRdx;
if (((HorRdx.matchAssociativeReduction(0, BinOp, DL) &&
HorRdx.tryToReduce(R, TTI)) ||
tryToVectorize(BinOp, R))) {
Changed = true;
it = BB->begin();
e = BB->end();
continue;
}
}
// Try to vectorize trees that start at compare instructions.
if (CmpInst *CI = dyn_cast<CmpInst>(it)) {
if (tryToVectorizePair(CI->getOperand(0), CI->getOperand(1), R)) {
Changed = true;
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
it = BB->begin();
e = BB->end();
continue;
}
for (int i = 0; i < 2; ++i) {
if (BinaryOperator *BI = dyn_cast<BinaryOperator>(CI->getOperand(i))) {
if (tryToVectorizePair(BI->getOperand(0), BI->getOperand(1), R)) {
Changed = true;
// We would like to start over since some instructions are deleted
// and the iterator may become invalid value.
it = BB->begin();
e = BB->end();
}
}
}
continue;
}
// Try to vectorize trees that start at insertelement instructions.
if (InsertElementInst *IE = dyn_cast<InsertElementInst>(it)) {
SmallVector<Value *, 8> Ops;
if (!findBuildVector(IE, Ops))
continue;
if (tryToVectorizeList(Ops, R)) {
Changed = true;
it = BB->begin();
e = BB->end();
}
continue;
}
}
return Changed;
}
bool SLPVectorizer::vectorizeStoreChains(BoUpSLP &R) {
bool Changed = false;
// Attempt to sort and vectorize each of the store-groups.
for (StoreListMap::iterator it = StoreRefs.begin(), e = StoreRefs.end();
it != e; ++it) {
if (it->second.size() < 2)
continue;
DEBUG(dbgs() << "SLP: Analyzing a store chain of length "
<< it->second.size() << ".\n");
// Process the stores in chunks of 16.
for (unsigned CI = 0, CE = it->second.size(); CI < CE; CI+=16) {
unsigned Len = std::min<unsigned>(CE - CI, 16);
ArrayRef<StoreInst *> Chunk(&it->second[CI], Len);
Changed |= vectorizeStores(Chunk, -SLPCostThreshold, R);
}
}
return Changed;
}
} // end anonymous namespace
char SLPVectorizer::ID = 0;
static const char lv_name[] = "SLP Vectorizer";
INITIALIZE_PASS_BEGIN(SLPVectorizer, SV_NAME, lv_name, false, false)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_END(SLPVectorizer, SV_NAME, lv_name, false, false)
namespace llvm {
Pass *createSLPVectorizerPass() { return new SLPVectorizer(); }
}
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