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llvm-6502/lib/Transforms/Vectorize/SLPVectorizer.cpp

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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 "));
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()) {}
~BuilderLocGuard() { if (Loc) Builder.SetInsertPoint(Loc); }
private:
// Prevent copying.
BuilderLocGuard(const BuilderLocGuard &);
BuilderLocGuard &operator=(const BuilderLocGuard &);
IRBuilder<> &Builder;
AssertingVH<Instruction> Loc;
};
/// A helper class for numbering instructions in multible blocks.
/// Numbers starts 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.
std::vector<Instruction *> 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.
void 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.
void buildTree(ArrayRef<Value *> Roots);
/// Clear the internal data structures that are created by 'buildTree'.
void deleteTree() {
VectorizableTree.clear();
ScalarToTreeEntry.clear();
MustGather.clear();
MemBarrierIgnoreList.clear();
}
/// \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 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);
/// Vectorizer a single entry in the tree.
Value *vectorizeTree(TreeEntry *E);
/// Vectorizer a single entry in the tree, starting in \p VL.
Value *vectorizeTree(ArrayRef<Value *> VL);
/// \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 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 Instrucion in the bundle \p VL.
Instruction *getLastInstruction(ArrayRef<Value *> VL);
/// \returns the Instruction at index \p Index which is in Block \p BB.
Instruction *getInstructionForIndex(unsigned Index, BasicBlock *BB);
/// \returns the index of the first User of \p VL.
int getFirstUserIndex(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) {
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;
/// 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.
std::map<BasicBlock *, BlockNumbering> BlocksNumbers;
// 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) {
deleteTree();
if (!getSameType(Roots))
return;
buildTree_rec(Roots, 0);
}
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;
}
// 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);
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();
for (unsigned i = 1, e = VL.size(); i < e; ++i) {
CmpInst *Cmp = cast<CmpInst>(VL[i]);
if (Cmp->getPredicate() != P0) {
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");
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;
}
DEBUG(dbgs() << "SLP: Total Cost " << Cost << ".\n");
return Cost;
}
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;
// Check that A and B are of the same type.
if (PtrA->getType() != PtrB->getType())
return false;
// Calculate the distance.
const SCEV *PtrSCEVA = SE->getSCEV(PtrA);
const SCEV *PtrSCEVB = SE->getSCEV(PtrB);
const SCEV *OffsetSCEV = SE->getMinusSCEV(PtrSCEVA, PtrSCEVB);
const SCEVConstant *ConstOffSCEV = dyn_cast<SCEVConstant>(OffsetSCEV);
// Non constant distance.
if (!ConstOffSCEV)
return false;
int64_t Offset = ConstOffSCEV->getValue()->getSExtValue();
Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
// The Instructions are connsecutive if the size of the first load/store is
// the same as the offset.
int64_t Sz = DL->getTypeStoreSize(Ty);
return ((-Offset) == Sz);
}
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;
}
Instruction *BoUpSLP::getInstructionForIndex(unsigned Index, BasicBlock *BB) {
BlockNumbering &BN = BlocksNumbers[BB];
return BN.getInstruction(Index);
}
int BoUpSLP::getFirstUserIndex(ArrayRef<Value *> VL) {
BasicBlock *BB = getSameBlock(VL);
assert(BB && "All instructions must come from the same block");
BlockNumbering &BN = BlocksNumbers[BB];
// Find the first user of the values.
int FirstUser = BN.getIndex(BB->getTerminator());
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) {
Instruction *Instr = dyn_cast<Instruction>(*U);
if (!Instr || Instr->getParent() != BB)
continue;
FirstUser = std::min(FirstUser, BN.getIndex(Instr));
}
}
return FirstUser;
}
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 *I = dyn_cast<Instruction>(Vec))
GatherSeq.insert(I);
}
return Vec;
}
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;
}
Type *ScalarTy = E->Scalars[0]->getType();
if (StoreInst *SI = dyn_cast<StoreInst>(E->Scalars[0]))
ScalarTy = SI->getValueOperand()->getType();
VectorType *VecTy = VectorType::get(ScalarTy, E->Scalars.size());
if (E->NeedToGather) {
return Gather(E->Scalars, VecTy);
}
Instruction *VL0 = cast<Instruction>(E->Scalars[0]);
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());
PHINode *NewPhi = Builder.CreatePHI(VecTy, PH->getNumIncomingValues());
E->VectorizedValue = NewPhi;
for (unsigned i = 0, e = PH->getNumIncomingValues(); i < e; ++i) {
ValueList Operands;
BasicBlock *IBB = PH->getIncomingBlock(i);
// 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());
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));
Builder.SetInsertPoint(getLastInstruction(E->Scalars));
Value *InVec = vectorizeTree(INVL);
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));
}
Builder.SetInsertPoint(getLastInstruction(E->Scalars));
Value *L = vectorizeTree(LHSV);
Value *R = vectorizeTree(RHSV);
Value *V;
CmpInst::Predicate P0 = dyn_cast<CmpInst>(VL0)->getPredicate();
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));
}
Builder.SetInsertPoint(getLastInstruction(E->Scalars));
Value *Cond = vectorizeTree(CondVec);
Value *True = vectorizeTree(TrueVec);
Value *False = vectorizeTree(FalseVec);
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));
}
Builder.SetInsertPoint(getLastInstruction(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");
}
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.
Builder.SetInsertPoint(getLastInstruction(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());
Builder.SetInsertPoint(getLastInstruction(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;
}
void BoUpSLP::vectorizeTree() {
Builder.SetInsertPoint(F->getEntryBlock().begin());
vectorizeTree(&VectorizableTree[0]);
// 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;
Value *Vec = Entry->VectorizedValue;
assert(Vec && "Can't find vectorizable value");
SmallVector<User*, 16> Users(Scalar->use_begin(), Scalar->use_end());
for (SmallVector<User*, 16>::iterator User = Users.begin(),
UE = Users.end(); User != UE; ++User) {
DEBUG(dbgs() << "SLP: \tupdating user " << **User << ".\n");
bool Gathered = MustGather.count(*User);
// Skip in-tree scalars that become vectors.
if (ScalarToTreeEntry.count(*User) && !Gathered) {
DEBUG(dbgs() << "SLP: \tUser will be removed soon:" <<
**User << ".\n");
int Idx = ScalarToTreeEntry[*User]; (void) Idx;
assert(!VectorizableTree[Idx].NeedToGather && "bad state ?");
continue;
}
if (!isa<Instruction>(*User))
continue;
// Generate extracts for out-of-tree users.
// Find the insertion point for the extractelement lane.
Instruction *Loc = 0;
if (PHINode *PN = dyn_cast<PHINode>(Vec)) {
Loc = PN->getParent()->getFirstInsertionPt();
} else if (Instruction *Iv = dyn_cast<Instruction>(Vec)){
Loc = ++((BasicBlock::iterator)*Iv);
} else {
Loc = F->getEntryBlock().begin();
}
Builder.SetInsertPoint(Loc);
Value *Ex = Builder.CreateExtractElement(Vec, Builder.getInt32(Lane));
(*User)->replaceUsesOfWith(Scalar, Ex);
DEBUG(dbgs() << "SLP: \tupdated user:" << **User << ".\n");
}
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) &&
"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();
}
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) {
InsertElementInst *Insert = dyn_cast<InsertElementInst>(it);
if (!Insert || !GatherSeq.count(Insert))
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 (Insert->isIdenticalTo(*v) &&
DT->dominates((*v)->getParent(), Insert->getParent())) {
Insert->replaceAllUsesWith(*v);
ToRemove.push_back(Insert);
Insert = 0;
break;
}
}
if (Insert)
Visited.insert(Insert);
}
}
// 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;
// Must have DataLayout. We can't require it because some tests run w/o
// triple.
if (!DL)
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 reductions.
Changed |= vectorizeChainsInBlock(BB, R);
// 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);
}
}
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. If \p NeedExtracts is true
/// then we calculate the cost of extracting the scalars from the vector.
/// \returns true if a value was vectorized.
bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R, bool NeedExtracts);
/// \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;
}
}
if (Changed || ChainLen > VF)
return Changed;
// Handle short chains. This helps us catch types such as <3 x float> that
// are smaller than vector size.
R.buildTree(Chain);
int Cost = R.getTreeCost();
if (Cost < CostThreshold) {
DEBUG(dbgs() << "SLP: Found store chain cost = " << Cost
<< " for size = " << ChainLen << "\n");
R.vectorizeTree();
return true;
}
return false;
}
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 loads 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, true);
}
bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
bool NeedExtracts) {
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 0;
unsigned Opcode0 = I0->getOpcode();
for (int i = 0, e = VL.size(); i < e; ++i) {
Type *Ty = VL[i]->getType();
if (Ty->isAggregateType() || Ty->isVectorTy())
return 0;
Instruction *Inst = dyn_cast<Instruction>(VL[i]);
if (!Inst || Inst->getOpcode() != Opcode0)
return 0;
}
R.buildTree(VL);
int Cost = R.getTreeCost();
int ExtrCost = NeedExtracts ? R.getGatherCost(VL) : 0;
DEBUG(dbgs() << "SLP: Cost of pair:" << Cost
<< " Cost of extract:" << ExtrCost << ".\n");
if ((Cost + ExtrCost) >= -SLPCostThreshold)
return false;
DEBUG(dbgs() << "SLP: Vectorizing pair.\n");
R.vectorizeTree();
return true;
}
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;
}
bool SLPVectorizer::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
bool Changed = false;
for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
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;
Value *Inst = BI->getOperand(0);
if (Inst == P)
Inst = BI->getOperand(1);
Changed |= tryToVectorize(dyn_cast<BinaryOperator>(Inst), R);
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;
continue;
}
for (int i = 0; i < 2; ++i)
if (BinaryOperator *BI = dyn_cast<BinaryOperator>(CI->getOperand(i)))
Changed |=
tryToVectorizePair(BI->getOperand(0), BI->getOperand(1), R);
continue;
}
}
// Scan the PHINodes in our successors in search for pairing hints.
for (succ_iterator it = succ_begin(BB), e = succ_end(BB); it != e; ++it) {
BasicBlock *Succ = *it;
SmallVector<Value *, 4> Incoming;
// Collect the incoming values from the PHIs.
for (BasicBlock::iterator instr = Succ->begin(), ie = Succ->end();
instr != ie; ++instr) {
PHINode *P = dyn_cast<PHINode>(instr);
if (!P)
break;
Value *V = P->getIncomingValueForBlock(BB);
if (Instruction *I = dyn_cast<Instruction>(V))
if (I->getParent() == BB)
Incoming.push_back(I);
}
if (Incoming.size() > 1)
Changed |= tryToVectorizeList(Incoming, R, true);
}
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");
Changed |= vectorizeStores(it->second, -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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