#define DEBUG_TYPE "gvn"
#include "llvm/Transforms/Scalar.h"
#include "llvm/BasicBlock.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Function.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Operator.h"
#include "llvm/Value.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Analysis/PHITransAddr.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
STATISTIC(NumGVNInstr, "Number of instructions deleted");
STATISTIC(NumGVNLoad, "Number of loads deleted");
STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
STATISTIC(NumGVNBlocks, "Number of blocks merged");
STATISTIC(NumPRELoad, "Number of loads PRE'd");
static cl::opt<bool> EnablePRE("enable-pre",
cl::init(true), cl::Hidden);
static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
static cl::opt<bool> EnableFullLoadPRE("enable-full-load-pre", cl::init(false));
namespace {
struct Expression {
enum ExpressionOpcode {
ADD = Instruction::Add,
FADD = Instruction::FAdd,
SUB = Instruction::Sub,
FSUB = Instruction::FSub,
MUL = Instruction::Mul,
FMUL = Instruction::FMul,
UDIV = Instruction::UDiv,
SDIV = Instruction::SDiv,
FDIV = Instruction::FDiv,
UREM = Instruction::URem,
SREM = Instruction::SRem,
FREM = Instruction::FRem,
SHL = Instruction::Shl,
LSHR = Instruction::LShr,
ASHR = Instruction::AShr,
AND = Instruction::And,
OR = Instruction::Or,
XOR = Instruction::Xor,
TRUNC = Instruction::Trunc,
ZEXT = Instruction::ZExt,
SEXT = Instruction::SExt,
FPTOUI = Instruction::FPToUI,
FPTOSI = Instruction::FPToSI,
UITOFP = Instruction::UIToFP,
SITOFP = Instruction::SIToFP,
FPTRUNC = Instruction::FPTrunc,
FPEXT = Instruction::FPExt,
PTRTOINT = Instruction::PtrToInt,
INTTOPTR = Instruction::IntToPtr,
BITCAST = Instruction::BitCast,
ICMPEQ, ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
SHUFFLE, SELECT, GEP, CALL, CONSTANT,
INSERTVALUE, EXTRACTVALUE, EMPTY, TOMBSTONE };
ExpressionOpcode opcode;
const Type* type;
SmallVector<uint32_t, 4> varargs;
Value *function;
Expression() { }
Expression(ExpressionOpcode o) : opcode(o) { }
bool operator==(const Expression &other) const {
if (opcode != other.opcode)
return false;
else if (opcode == EMPTY || opcode == TOMBSTONE)
return true;
else if (type != other.type)
return false;
else if (function != other.function)
return false;
else {
if (varargs.size() != other.varargs.size())
return false;
for (size_t i = 0; i < varargs.size(); ++i)
if (varargs[i] != other.varargs[i])
return false;
return true;
}
}
bool operator!=(const Expression &other) const {
return !(*this == other);
}
};
class ValueTable {
private:
DenseMap<Value*, uint32_t> valueNumbering;
DenseMap<Expression, uint32_t> expressionNumbering;
AliasAnalysis* AA;
MemoryDependenceAnalysis* MD;
DominatorTree* DT;
uint32_t nextValueNumber;
Expression::ExpressionOpcode getOpcode(CmpInst* C);
Expression create_expression(BinaryOperator* BO);
Expression create_expression(CmpInst* C);
Expression create_expression(ShuffleVectorInst* V);
Expression create_expression(ExtractElementInst* C);
Expression create_expression(InsertElementInst* V);
Expression create_expression(SelectInst* V);
Expression create_expression(CastInst* C);
Expression create_expression(GetElementPtrInst* G);
Expression create_expression(CallInst* C);
Expression create_expression(Constant* C);
Expression create_expression(ExtractValueInst* C);
Expression create_expression(InsertValueInst* C);
uint32_t lookup_or_add_call(CallInst* C);
public:
ValueTable() : nextValueNumber(1) { }
uint32_t lookup_or_add(Value *V);
uint32_t lookup(Value *V) const;
void add(Value *V, uint32_t num);
void clear();
void erase(Value *v);
unsigned size();
void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
AliasAnalysis *getAliasAnalysis() const { return AA; }
void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
void setDomTree(DominatorTree* D) { DT = D; }
uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
void verifyRemoved(const Value *) const;
};
}
namespace llvm {
template <> struct DenseMapInfo<Expression> {
static inline Expression getEmptyKey() {
return Expression(Expression::EMPTY);
}
static inline Expression getTombstoneKey() {
return Expression(Expression::TOMBSTONE);
}
static unsigned getHashValue(const Expression e) {
unsigned hash = e.opcode;
hash = ((unsigned)((uintptr_t)e.type >> 4) ^
(unsigned)((uintptr_t)e.type >> 9));
for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
E = e.varargs.end(); I != E; ++I)
hash = *I + hash * 37;
hash = ((unsigned)((uintptr_t)e.function >> 4) ^
(unsigned)((uintptr_t)e.function >> 9)) +
hash * 37;
return hash;
}
static bool isEqual(const Expression &LHS, const Expression &RHS) {
return LHS == RHS;
}
};
template <>
struct isPodLike<Expression> { static const bool value = true; };
}
Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
if (isa<ICmpInst>(C)) {
switch (C->getPredicate()) {
default: llvm_unreachable("Comparison with unknown predicate?");
case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
case ICmpInst::ICMP_NE: return Expression::ICMPNE;
case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
case ICmpInst::ICMP_UGE: return Expression::ICMPUGE;
case ICmpInst::ICMP_ULT: return Expression::ICMPULT;
case ICmpInst::ICMP_ULE: return Expression::ICMPULE;
case ICmpInst::ICMP_SGT: return Expression::ICMPSGT;
case ICmpInst::ICMP_SGE: return Expression::ICMPSGE;
case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
}
} else {
switch (C->getPredicate()) {
default: llvm_unreachable("Comparison with unknown predicate?");
case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
}
}
}
Expression ValueTable::create_expression(CallInst* C) {
Expression e;
e.type = C->getType();
e.function = C->getCalledFunction();
e.opcode = Expression::CALL;
for (CallInst::op_iterator I = C->op_begin()+1, E = C->op_end();
I != E; ++I)
e.varargs.push_back(lookup_or_add(*I));
return e;
}
Expression ValueTable::create_expression(BinaryOperator* BO) {
Expression e;
e.varargs.push_back(lookup_or_add(BO->getOperand(0)));
e.varargs.push_back(lookup_or_add(BO->getOperand(1)));
e.function = 0;
e.type = BO->getType();
e.opcode = static_cast<Expression::ExpressionOpcode>(BO->getOpcode());
return e;
}
Expression ValueTable::create_expression(CmpInst* C) {
Expression e;
e.varargs.push_back(lookup_or_add(C->getOperand(0)));
e.varargs.push_back(lookup_or_add(C->getOperand(1)));
e.function = 0;
e.type = C->getType();
e.opcode = getOpcode(C);
return e;
}
Expression ValueTable::create_expression(CastInst* C) {
Expression e;
e.varargs.push_back(lookup_or_add(C->getOperand(0)));
e.function = 0;
e.type = C->getType();
e.opcode = static_cast<Expression::ExpressionOpcode>(C->getOpcode());
return e;
}
Expression ValueTable::create_expression(ShuffleVectorInst* S) {
Expression e;
e.varargs.push_back(lookup_or_add(S->getOperand(0)));
e.varargs.push_back(lookup_or_add(S->getOperand(1)));
e.varargs.push_back(lookup_or_add(S->getOperand(2)));
e.function = 0;
e.type = S->getType();
e.opcode = Expression::SHUFFLE;
return e;
}
Expression ValueTable::create_expression(ExtractElementInst* E) {
Expression e;
e.varargs.push_back(lookup_or_add(E->getOperand(0)));
e.varargs.push_back(lookup_or_add(E->getOperand(1)));
e.function = 0;
e.type = E->getType();
e.opcode = Expression::EXTRACT;
return e;
}
Expression ValueTable::create_expression(InsertElementInst* I) {
Expression e;
e.varargs.push_back(lookup_or_add(I->getOperand(0)));
e.varargs.push_back(lookup_or_add(I->getOperand(1)));
e.varargs.push_back(lookup_or_add(I->getOperand(2)));
e.function = 0;
e.type = I->getType();
e.opcode = Expression::INSERT;
return e;
}
Expression ValueTable::create_expression(SelectInst* I) {
Expression e;
e.varargs.push_back(lookup_or_add(I->getCondition()));
e.varargs.push_back(lookup_or_add(I->getTrueValue()));
e.varargs.push_back(lookup_or_add(I->getFalseValue()));
e.function = 0;
e.type = I->getType();
e.opcode = Expression::SELECT;
return e;
}
Expression ValueTable::create_expression(GetElementPtrInst* G) {
Expression e;
e.varargs.push_back(lookup_or_add(G->getPointerOperand()));
e.function = 0;
e.type = G->getType();
e.opcode = Expression::GEP;
for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
I != E; ++I)
e.varargs.push_back(lookup_or_add(*I));
return e;
}
Expression ValueTable::create_expression(ExtractValueInst* E) {
Expression e;
e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
II != IE; ++II)
e.varargs.push_back(*II);
e.function = 0;
e.type = E->getType();
e.opcode = Expression::EXTRACTVALUE;
return e;
}
Expression ValueTable::create_expression(InsertValueInst* E) {
Expression e;
e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
e.varargs.push_back(lookup_or_add(E->getInsertedValueOperand()));
for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
II != IE; ++II)
e.varargs.push_back(*II);
e.function = 0;
e.type = E->getType();
e.opcode = Expression::INSERTVALUE;
return e;
}
void ValueTable::add(Value *V, uint32_t num) {
valueNumbering.insert(std::make_pair(V, num));
}
uint32_t ValueTable::lookup_or_add_call(CallInst* C) {
if (AA->doesNotAccessMemory(C)) {
Expression exp = create_expression(C);
uint32_t& e = expressionNumbering[exp];
if (!e) e = nextValueNumber++;
valueNumbering[C] = e;
return e;
} else if (AA->onlyReadsMemory(C)) {
Expression exp = create_expression(C);
uint32_t& e = expressionNumbering[exp];
if (!e) {
e = nextValueNumber++;
valueNumbering[C] = e;
return e;
}
if (!MD) {
e = nextValueNumber++;
valueNumbering[C] = e;
return e;
}
MemDepResult local_dep = MD->getDependency(C);
if (!local_dep.isDef() && !local_dep.isNonLocal()) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
if (local_dep.isDef()) {
CallInst* local_cdep = cast<CallInst>(local_dep.getInst());
if (local_cdep->getNumOperands() != C->getNumOperands()) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
for (unsigned i = 1; i < C->getNumOperands(); ++i) {
uint32_t c_vn = lookup_or_add(C->getOperand(i));
uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
if (c_vn != cd_vn) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
}
uint32_t v = lookup_or_add(local_cdep);
valueNumbering[C] = v;
return v;
}
const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
MD->getNonLocalCallDependency(CallSite(C));
CallInst* cdep = 0;
for (unsigned i = 0, e = deps.size(); i != e; ++i) {
const NonLocalDepEntry *I = &deps[i];
if (I->getResult().isNonLocal())
continue;
if (I->getResult().isClobber() || cdep != 0) {
cdep = 0;
break;
}
CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->getResult().getInst());
if (NonLocalDepCall && DT->properlyDominates(I->getBB(), C->getParent())){
cdep = NonLocalDepCall;
continue;
}
cdep = 0;
break;
}
if (!cdep) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
if (cdep->getNumOperands() != C->getNumOperands()) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
for (unsigned i = 1; i < C->getNumOperands(); ++i) {
uint32_t c_vn = lookup_or_add(C->getOperand(i));
uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
if (c_vn != cd_vn) {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
}
uint32_t v = lookup_or_add(cdep);
valueNumbering[C] = v;
return v;
} else {
valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
}
uint32_t ValueTable::lookup_or_add(Value *V) {
DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
if (VI != valueNumbering.end())
return VI->second;
if (!isa<Instruction>(V)) {
valueNumbering[V] = nextValueNumber;
return nextValueNumber++;
}
Instruction* I = cast<Instruction>(V);
Expression exp;
switch (I->getOpcode()) {
case Instruction::Call:
return lookup_or_add_call(cast<CallInst>(I));
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:
exp = create_expression(cast<BinaryOperator>(I));
break;
case Instruction::ICmp:
case Instruction::FCmp:
exp = create_expression(cast<CmpInst>(I));
break;
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::UIToFP:
case Instruction::SIToFP:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::BitCast:
exp = create_expression(cast<CastInst>(I));
break;
case Instruction::Select:
exp = create_expression(cast<SelectInst>(I));
break;
case Instruction::ExtractElement:
exp = create_expression(cast<ExtractElementInst>(I));
break;
case Instruction::InsertElement:
exp = create_expression(cast<InsertElementInst>(I));
break;
case Instruction::ShuffleVector:
exp = create_expression(cast<ShuffleVectorInst>(I));
break;
case Instruction::ExtractValue:
exp = create_expression(cast<ExtractValueInst>(I));
break;
case Instruction::InsertValue:
exp = create_expression(cast<InsertValueInst>(I));
break;
case Instruction::GetElementPtr:
exp = create_expression(cast<GetElementPtrInst>(I));
break;
default:
valueNumbering[V] = nextValueNumber;
return nextValueNumber++;
}
uint32_t& e = expressionNumbering[exp];
if (!e) e = nextValueNumber++;
valueNumbering[V] = e;
return e;
}
uint32_t ValueTable::lookup(Value *V) const {
DenseMap<Value*, uint32_t>::const_iterator VI = valueNumbering.find(V);
assert(VI != valueNumbering.end() && "Value not numbered?");
return VI->second;
}
void ValueTable::clear() {
valueNumbering.clear();
expressionNumbering.clear();
nextValueNumber = 1;
}
void ValueTable::erase(Value *V) {
valueNumbering.erase(V);
}
void ValueTable::verifyRemoved(const Value *V) const {
for (DenseMap<Value*, uint32_t>::const_iterator
I = valueNumbering.begin(), E = valueNumbering.end(); I != E; ++I) {
assert(I->first != V && "Inst still occurs in value numbering map!");
}
}
namespace {
struct ValueNumberScope {
ValueNumberScope* parent;
DenseMap<uint32_t, Value*> table;
ValueNumberScope(ValueNumberScope* p) : parent(p) { }
};
}
namespace {
class GVN : public FunctionPass {
bool runOnFunction(Function &F);
public:
static char ID; explicit GVN(bool noloads = false)
: FunctionPass(&ID), NoLoads(noloads), MD(0) { }
private:
bool NoLoads;
MemoryDependenceAnalysis *MD;
DominatorTree *DT;
ValueTable VN;
DenseMap<BasicBlock*, ValueNumberScope*> localAvail;
SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
if (!NoLoads)
AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<AliasAnalysis>();
}
bool processLoad(LoadInst* L,
SmallVectorImpl<Instruction*> &toErase);
bool processInstruction(Instruction *I,
SmallVectorImpl<Instruction*> &toErase);
bool processNonLocalLoad(LoadInst* L,
SmallVectorImpl<Instruction*> &toErase);
bool processBlock(BasicBlock *BB);
void dump(DenseMap<uint32_t, Value*>& d);
bool iterateOnFunction(Function &F);
Value *CollapsePhi(PHINode* p);
bool performPRE(Function& F);
Value *lookupNumber(BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
void verifyRemoved(const Instruction *I) const;
bool splitCriticalEdges();
};
char GVN::ID = 0;
}
FunctionPass *llvm::createGVNPass(bool NoLoads) {
return new GVN(NoLoads);
}
static RegisterPass<GVN> X("gvn",
"Global Value Numbering");
void GVN::dump(DenseMap<uint32_t, Value*>& d) {
errs() << "{\n";
for (DenseMap<uint32_t, Value*>::iterator I = d.begin(),
E = d.end(); I != E; ++I) {
errs() << I->first << "\n";
I->second->dump();
}
errs() << "}\n";
}
static bool isSafeReplacement(PHINode* p, Instruction *inst) {
if (!isa<PHINode>(inst))
return true;
for (Instruction::use_iterator UI = p->use_begin(), E = p->use_end();
UI != E; ++UI)
if (PHINode* use_phi = dyn_cast<PHINode>(UI))
if (use_phi->getParent() == inst->getParent())
return false;
return true;
}
Value *GVN::CollapsePhi(PHINode *PN) {
Value *ConstVal = PN->hasConstantValue(DT);
if (!ConstVal) return 0;
Instruction *Inst = dyn_cast<Instruction>(ConstVal);
if (!Inst)
return ConstVal;
if (DT->dominates(Inst, PN))
if (isSafeReplacement(PN, Inst))
return Inst;
return 0;
}
static bool IsValueFullyAvailableInBlock(BasicBlock *BB,
DenseMap<BasicBlock*, char> &FullyAvailableBlocks) {
std::pair<DenseMap<BasicBlock*, char>::iterator, char> IV =
FullyAvailableBlocks.insert(std::make_pair(BB, 2));
if (!IV.second) {
if (IV.first->second == 2)
IV.first->second = 3;
return IV.first->second != 0;
}
pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
if (PI == PE)
goto SpeculationFailure;
for (; PI != PE; ++PI)
if (!IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks))
goto SpeculationFailure;
return true;
SpeculationFailure:
char &BBVal = FullyAvailableBlocks[BB];
if (BBVal == 2) {
BBVal = 0;
return false;
}
SmallVector<BasicBlock*, 32> BBWorklist;
BBWorklist.push_back(BB);
do {
BasicBlock *Entry = BBWorklist.pop_back_val();
char &EntryVal = FullyAvailableBlocks[Entry];
if (EntryVal == 0) continue;
EntryVal = 0;
for (succ_iterator I = succ_begin(Entry), E = succ_end(Entry); I != E; ++I)
BBWorklist.push_back(*I);
} while (!BBWorklist.empty());
return false;
}
static bool CanCoerceMustAliasedValueToLoad(Value *StoredVal,
const Type *LoadTy,
const TargetData &TD) {
if (LoadTy->isStructTy() || LoadTy->isArrayTy() ||
StoredVal->getType()->isStructTy() ||
StoredVal->getType()->isArrayTy())
return false;
if (TD.getTypeSizeInBits(StoredVal->getType()) <
TD.getTypeSizeInBits(LoadTy))
return false;
return true;
}
static Value *CoerceAvailableValueToLoadType(Value *StoredVal,
const Type *LoadedTy,
Instruction *InsertPt,
const TargetData &TD) {
if (!CanCoerceMustAliasedValueToLoad(StoredVal, LoadedTy, TD))
return 0;
const Type *StoredValTy = StoredVal->getType();
uint64_t StoreSize = TD.getTypeSizeInBits(StoredValTy);
uint64_t LoadSize = TD.getTypeSizeInBits(LoadedTy);
if (StoreSize == LoadSize) {
if (StoredValTy->isPointerTy() && LoadedTy->isPointerTy()) {
return new BitCastInst(StoredVal, LoadedTy, "", InsertPt);
}
if (StoredValTy->isPointerTy()) {
StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
}
const Type *TypeToCastTo = LoadedTy;
if (TypeToCastTo->isPointerTy())
TypeToCastTo = TD.getIntPtrType(StoredValTy->getContext());
if (StoredValTy != TypeToCastTo)
StoredVal = new BitCastInst(StoredVal, TypeToCastTo, "", InsertPt);
if (LoadedTy->isPointerTy())
StoredVal = new IntToPtrInst(StoredVal, LoadedTy, "", InsertPt);
return StoredVal;
}
assert(StoreSize >= LoadSize && "CanCoerceMustAliasedValueToLoad fail");
if (StoredValTy->isPointerTy()) {
StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
}
if (!StoredValTy->isIntegerTy()) {
StoredValTy = IntegerType::get(StoredValTy->getContext(), StoreSize);
StoredVal = new BitCastInst(StoredVal, StoredValTy, "", InsertPt);
}
if (TD.isBigEndian()) {
Constant *Val = ConstantInt::get(StoredVal->getType(), StoreSize-LoadSize);
StoredVal = BinaryOperator::CreateLShr(StoredVal, Val, "tmp", InsertPt);
}
const Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadSize);
StoredVal = new TruncInst(StoredVal, NewIntTy, "trunc", InsertPt);
if (LoadedTy == NewIntTy)
return StoredVal;
if (LoadedTy->isPointerTy())
return new IntToPtrInst(StoredVal, LoadedTy, "inttoptr", InsertPt);
return new BitCastInst(StoredVal, LoadedTy, "bitcast", InsertPt);
}
static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
const TargetData &TD) {
Operator *PtrOp = dyn_cast<Operator>(Ptr);
if (PtrOp == 0) return Ptr;
if (PtrOp->getOpcode() == Instruction::BitCast)
return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
gep_type_iterator GTI = gep_type_begin(GEP);
for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
++I, ++GTI) {
ConstantInt *OpC = cast<ConstantInt>(*I);
if (OpC->isZero()) continue;
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
} else {
uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
Offset += OpC->getSExtValue()*Size;
}
}
unsigned PtrSize = TD.getPointerSizeInBits();
if (PtrSize < 64)
Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
}
static int AnalyzeLoadFromClobberingWrite(const Type *LoadTy, Value *LoadPtr,
Value *WritePtr,
uint64_t WriteSizeInBits,
const TargetData &TD) {
if (LoadTy->isStructTy() || LoadTy->isArrayTy())
return -1;
int64_t StoreOffset = 0, LoadOffset = 0;
Value *StoreBase = GetBaseWithConstantOffset(WritePtr, StoreOffset, TD);
Value *LoadBase =
GetBaseWithConstantOffset(LoadPtr, LoadOffset, TD);
if (StoreBase != LoadBase)
return -1;
if (LoadOffset == StoreOffset) {
#if 0
dbgs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *WritePtr << "\n"
<< "Store Offs = " << StoreOffset << "\n"
<< "Load Ptr = " << *LoadPtr << "\n";
abort();
#endif
return -1;
}
uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy);
if ((WriteSizeInBits & 7) | (LoadSize & 7))
return -1;
uint64_t StoreSize = WriteSizeInBits >> 3; LoadSize >>= 3;
bool isAAFailure = false;
if (StoreOffset < LoadOffset) {
isAAFailure = StoreOffset+int64_t(StoreSize) <= LoadOffset;
} else {
isAAFailure = LoadOffset+int64_t(LoadSize) <= StoreOffset;
}
if (isAAFailure) {
#if 0
dbgs() << "STORE LOAD DEP WITH COMMON BASE:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *WritePtr << "\n"
<< "Store Offs = " << StoreOffset << "\n"
<< "Load Ptr = " << *LoadPtr << "\n";
abort();
#endif
return -1;
}
if (StoreOffset > LoadOffset ||
StoreOffset+StoreSize < LoadOffset+LoadSize)
return -1;
return LoadOffset-StoreOffset;
}
static int AnalyzeLoadFromClobberingStore(const Type *LoadTy, Value *LoadPtr,
StoreInst *DepSI,
const TargetData &TD) {
if (DepSI->getOperand(0)->getType()->isStructTy() ||
DepSI->getOperand(0)->getType()->isArrayTy())
return -1;
Value *StorePtr = DepSI->getPointerOperand();
uint64_t StoreSize = TD.getTypeSizeInBits(DepSI->getOperand(0)->getType());
return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
StorePtr, StoreSize, TD);
}
static int AnalyzeLoadFromClobberingMemInst(const Type *LoadTy, Value *LoadPtr,
MemIntrinsic *MI,
const TargetData &TD) {
ConstantInt *SizeCst = dyn_cast<ConstantInt>(MI->getLength());
if (SizeCst == 0) return -1;
uint64_t MemSizeInBits = SizeCst->getZExtValue()*8;
if (MI->getIntrinsicID() == Intrinsic::memset)
return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr, MI->getDest(),
MemSizeInBits, TD);
MemTransferInst *MTI = cast<MemTransferInst>(MI);
Constant *Src = dyn_cast<Constant>(MTI->getSource());
if (Src == 0) return -1;
GlobalVariable *GV = dyn_cast<GlobalVariable>(Src->getUnderlyingObject());
if (GV == 0 || !GV->isConstant()) return -1;
int Offset = AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
MI->getDest(), MemSizeInBits, TD);
if (Offset == -1)
return Offset;
Src = ConstantExpr::getBitCast(Src,
llvm::Type::getInt8PtrTy(Src->getContext()));
Constant *OffsetCst =
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
if (ConstantFoldLoadFromConstPtr(Src, &TD))
return Offset;
return -1;
}
static Value *GetStoreValueForLoad(Value *SrcVal, unsigned Offset,
const Type *LoadTy,
Instruction *InsertPt, const TargetData &TD){
LLVMContext &Ctx = SrcVal->getType()->getContext();
uint64_t StoreSize = TD.getTypeSizeInBits(SrcVal->getType())/8;
uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
if (SrcVal->getType()->isPointerTy())
SrcVal = Builder.CreatePtrToInt(SrcVal, TD.getIntPtrType(Ctx), "tmp");
if (!SrcVal->getType()->isIntegerTy())
SrcVal = Builder.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize*8),
"tmp");
unsigned ShiftAmt;
if (TD.isLittleEndian())
ShiftAmt = Offset*8;
else
ShiftAmt = (StoreSize-LoadSize-Offset)*8;
if (ShiftAmt)
SrcVal = Builder.CreateLShr(SrcVal, ShiftAmt, "tmp");
if (LoadSize != StoreSize)
SrcVal = Builder.CreateTrunc(SrcVal, IntegerType::get(Ctx, LoadSize*8),
"tmp");
return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, TD);
}
static Value *GetMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
const Type *LoadTy, Instruction *InsertPt,
const TargetData &TD){
LLVMContext &Ctx = LoadTy->getContext();
uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
if (MemSetInst *MSI = dyn_cast<MemSetInst>(SrcInst)) {
Value *Val = MSI->getValue();
if (LoadSize != 1)
Val = Builder.CreateZExt(Val, IntegerType::get(Ctx, LoadSize*8));
Value *OneElt = Val;
for (unsigned NumBytesSet = 1; NumBytesSet != LoadSize; ) {
if (NumBytesSet*2 <= LoadSize) {
Value *ShVal = Builder.CreateShl(Val, NumBytesSet*8);
Val = Builder.CreateOr(Val, ShVal);
NumBytesSet <<= 1;
continue;
}
Value *ShVal = Builder.CreateShl(Val, 1*8);
Val = Builder.CreateOr(OneElt, ShVal);
++NumBytesSet;
}
return CoerceAvailableValueToLoadType(Val, LoadTy, InsertPt, TD);
}
MemTransferInst *MTI = cast<MemTransferInst>(SrcInst);
Constant *Src = cast<Constant>(MTI->getSource());
Src = ConstantExpr::getBitCast(Src,
llvm::Type::getInt8PtrTy(Src->getContext()));
Constant *OffsetCst =
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
return ConstantFoldLoadFromConstPtr(Src, &TD);
}
struct AvailableValueInBlock {
BasicBlock *BB;
enum ValType {
SimpleVal, MemIntrin };
PointerIntPair<Value *, 1, ValType> Val;
unsigned Offset;
static AvailableValueInBlock get(BasicBlock *BB, Value *V,
unsigned Offset = 0) {
AvailableValueInBlock Res;
Res.BB = BB;
Res.Val.setPointer(V);
Res.Val.setInt(SimpleVal);
Res.Offset = Offset;
return Res;
}
static AvailableValueInBlock getMI(BasicBlock *BB, MemIntrinsic *MI,
unsigned Offset = 0) {
AvailableValueInBlock Res;
Res.BB = BB;
Res.Val.setPointer(MI);
Res.Val.setInt(MemIntrin);
Res.Offset = Offset;
return Res;
}
bool isSimpleValue() const { return Val.getInt() == SimpleVal; }
Value *getSimpleValue() const {
assert(isSimpleValue() && "Wrong accessor");
return Val.getPointer();
}
MemIntrinsic *getMemIntrinValue() const {
assert(!isSimpleValue() && "Wrong accessor");
return cast<MemIntrinsic>(Val.getPointer());
}
Value *MaterializeAdjustedValue(const Type *LoadTy,
const TargetData *TD) const {
Value *Res;
if (isSimpleValue()) {
Res = getSimpleValue();
if (Res->getType() != LoadTy) {
assert(TD && "Need target data to handle type mismatch case");
Res = GetStoreValueForLoad(Res, Offset, LoadTy, BB->getTerminator(),
*TD);
DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\nOffset: " << Offset << " "
<< *getSimpleValue() << '\n'
<< *Res << '\n' << "\n\n\n");
}
} else {
Res = GetMemInstValueForLoad(getMemIntrinValue(), Offset,
LoadTy, BB->getTerminator(), *TD);
DEBUG(errs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
<< " " << *getMemIntrinValue() << '\n'
<< *Res << '\n' << "\n\n\n");
}
return Res;
}
};
static Value *ConstructSSAForLoadSet(LoadInst *LI,
SmallVectorImpl<AvailableValueInBlock> &ValuesPerBlock,
const TargetData *TD,
const DominatorTree &DT,
AliasAnalysis *AA) {
if (ValuesPerBlock.size() == 1 &&
DT.properlyDominates(ValuesPerBlock[0].BB, LI->getParent()))
return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), TD);
SmallVector<PHINode*, 8> NewPHIs;
SSAUpdater SSAUpdate(&NewPHIs);
SSAUpdate.Initialize(LI);
const Type *LoadTy = LI->getType();
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
const AvailableValueInBlock &AV = ValuesPerBlock[i];
BasicBlock *BB = AV.BB;
if (SSAUpdate.HasValueForBlock(BB))
continue;
SSAUpdate.AddAvailableValue(BB, AV.MaterializeAdjustedValue(LoadTy, TD));
}
Value *V = SSAUpdate.GetValueInMiddleOfBlock(LI->getParent());
if (V->getType()->isPointerTy())
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
AA->copyValue(LI, NewPHIs[i]);
return V;
}
static bool isLifetimeStart(Instruction *Inst) {
if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst))
return II->getIntrinsicID() == Intrinsic::lifetime_start;
return false;
}
bool GVN::processNonLocalLoad(LoadInst *LI,
SmallVectorImpl<Instruction*> &toErase) {
SmallVector<NonLocalDepResult, 64> Deps;
MD->getNonLocalPointerDependency(LI->getOperand(0), true, LI->getParent(),
Deps);
if (Deps.size() > 100)
return false;
if (Deps.size() == 1 && Deps[0].getResult().isClobber()) {
DEBUG(
dbgs() << "GVN: non-local load ";
WriteAsOperand(dbgs(), LI);
dbgs() << " is clobbered by " << *Deps[0].getResult().getInst() << '\n';
);
return false;
}
SmallVector<AvailableValueInBlock, 16> ValuesPerBlock;
SmallVector<BasicBlock*, 16> UnavailableBlocks;
const TargetData *TD = 0;
for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
BasicBlock *DepBB = Deps[i].getBB();
MemDepResult DepInfo = Deps[i].getResult();
if (DepInfo.isClobber()) {
Value *Address = Deps[i].getAddress();
if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
if (TD == 0)
TD = getAnalysisIfAvailable<TargetData>();
if (TD && Address) {
int Offset = AnalyzeLoadFromClobberingStore(LI->getType(), Address,
DepSI, *TD);
if (Offset != -1) {
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
DepSI->getOperand(0),
Offset));
continue;
}
}
}
if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(DepInfo.getInst())) {
if (TD == 0)
TD = getAnalysisIfAvailable<TargetData>();
if (TD && Address) {
int Offset = AnalyzeLoadFromClobberingMemInst(LI->getType(), Address,
DepMI, *TD);
if (Offset != -1) {
ValuesPerBlock.push_back(AvailableValueInBlock::getMI(DepBB, DepMI,
Offset));
continue;
}
}
}
UnavailableBlocks.push_back(DepBB);
continue;
}
Instruction *DepInst = DepInfo.getInst();
if (isa<AllocaInst>(DepInst) || isMalloc(DepInst) ||
isLifetimeStart(DepInst)) {
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
UndefValue::get(LI->getType())));
continue;
}
if (StoreInst *S = dyn_cast<StoreInst>(DepInst)) {
if (S->getOperand(0)->getType() != LI->getType()) {
if (TD == 0)
TD = getAnalysisIfAvailable<TargetData>();
if (TD == 0 || !CanCoerceMustAliasedValueToLoad(S->getOperand(0),
LI->getType(), *TD)) {
UnavailableBlocks.push_back(DepBB);
continue;
}
}
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
S->getOperand(0)));
continue;
}
if (LoadInst *LD = dyn_cast<LoadInst>(DepInst)) {
if (LD->getType() != LI->getType()) {
if (TD == 0)
TD = getAnalysisIfAvailable<TargetData>();
if (TD == 0 || !CanCoerceMustAliasedValueToLoad(LD, LI->getType(),*TD)){
UnavailableBlocks.push_back(DepBB);
continue;
}
}
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB, LD));
continue;
}
UnavailableBlocks.push_back(DepBB);
continue;
}
if (ValuesPerBlock.empty()) return false;
if (UnavailableBlocks.empty()) {
DEBUG(dbgs() << "GVN REMOVING NONLOCAL LOAD: " << *LI << '\n');
Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
VN.getAliasAnalysis());
LI->replaceAllUsesWith(V);
if (isa<PHINode>(V))
V->takeName(LI);
if (V->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
VN.erase(LI);
toErase.push_back(LI);
NumGVNLoad++;
return true;
}
if (!EnablePRE || !EnableLoadPRE)
return false;
SmallPtrSet<BasicBlock *, 4> Blockers;
for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
Blockers.insert(UnavailableBlocks[i]);
BasicBlock *LoadBB = LI->getParent();
BasicBlock *TmpBB = LoadBB;
bool isSinglePred = false;
bool allSingleSucc = true;
while (TmpBB->getSinglePredecessor()) {
isSinglePred = true;
TmpBB = TmpBB->getSinglePredecessor();
if (TmpBB == LoadBB) return false;
if (Blockers.count(TmpBB))
return false;
if (TmpBB->getTerminator()->getNumSuccessors() != 1)
allSingleSucc = false;
}
assert(TmpBB);
LoadBB = TmpBB;
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
if (ValuesPerBlock[i].isSimpleValue() &&
ValuesPerBlock[i].getSimpleValue() == LI) {
if (!EnableFullLoadPRE || e == 1)
return false;
}
}
if (isSinglePred) {
bool isHot = false;
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
const AvailableValueInBlock &AV = ValuesPerBlock[i];
if (AV.isSimpleValue())
if (Instruction *I = dyn_cast<Instruction>(AV.getSimpleValue()))
if (DT->dominates(LI, I)) {
isHot = true;
break;
}
}
if (!isHot)
return false;
}
DenseMap<BasicBlock*, Value*> PredLoads;
DenseMap<BasicBlock*, char> FullyAvailableBlocks;
for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
FullyAvailableBlocks[ValuesPerBlock[i].BB] = true;
for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
FullyAvailableBlocks[UnavailableBlocks[i]] = false;
bool NeedToSplitEdges = false;
for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
PI != E; ++PI) {
BasicBlock *Pred = *PI;
if (IsValueFullyAvailableInBlock(Pred, FullyAvailableBlocks)) {
continue;
}
PredLoads[Pred] = 0;
if (Pred->getTerminator()->getNumSuccessors() != 1) {
if (isa<IndirectBrInst>(Pred->getTerminator())) {
DEBUG(dbgs() << "COULD NOT PRE LOAD BECAUSE OF INDBR CRITICAL EDGE '"
<< Pred->getName() << "': " << *LI << '\n');
return false;
}
unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
toSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
NeedToSplitEdges = true;
}
}
if (NeedToSplitEdges)
return false;
unsigned NumUnavailablePreds = PredLoads.size();
assert(NumUnavailablePreds != 0 &&
"Fully available value should be eliminated above!");
if (!EnableFullLoadPRE) {
if (NumUnavailablePreds != 1)
return false;
}
bool CanDoPRE = true;
SmallVector<Instruction*, 8> NewInsts;
for (DenseMap<BasicBlock*, Value*>::iterator I = PredLoads.begin(),
E = PredLoads.end(); I != E; ++I) {
BasicBlock *UnavailablePred = I->first;
PHITransAddr Address(LI->getOperand(0), TD);
Value *LoadPtr = 0;
if (allSingleSucc) {
LoadPtr = Address.PHITranslateWithInsertion(LoadBB, UnavailablePred,
*DT, NewInsts);
} else {
Address.PHITranslateValue(LoadBB, UnavailablePred, DT);
LoadPtr = Address.getAddr();
}
if (LoadPtr == 0) {
DEBUG(dbgs() << "COULDN'T INSERT PHI TRANSLATED VALUE OF: "
<< *LI->getOperand(0) << "\n");
CanDoPRE = false;
break;
}
if (!allSingleSucc &&
!isSafeToLoadUnconditionally(LoadPtr,
UnavailablePred->getTerminator(),
LI->getAlignment(), TD)) {
CanDoPRE = false;
break;
}
I->second = LoadPtr;
}
if (!CanDoPRE) {
while (!NewInsts.empty())
NewInsts.pop_back_val()->eraseFromParent();
return false;
}
DEBUG(dbgs() << "GVN REMOVING PRE LOAD: " << *LI << '\n');
DEBUG(if (!NewInsts.empty())
dbgs() << "INSERTED " << NewInsts.size() << " INSTS: "
<< *NewInsts.back() << '\n');
for (unsigned i = 0, e = NewInsts.size(); i != e; ++i) {
VN.lookup_or_add(NewInsts[i]);
}
for (DenseMap<BasicBlock*, Value*>::iterator I = PredLoads.begin(),
E = PredLoads.end(); I != E; ++I) {
BasicBlock *UnavailablePred = I->first;
Value *LoadPtr = I->second;
Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
LI->getAlignment(),
UnavailablePred->getTerminator());
ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,
NewLoad));
MD->invalidateCachedPointerInfo(LoadPtr);
DEBUG(dbgs() << "GVN INSERTED " << *NewLoad << '\n');
}
Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
VN.getAliasAnalysis());
LI->replaceAllUsesWith(V);
if (isa<PHINode>(V))
V->takeName(LI);
if (V->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(V);
VN.erase(LI);
toErase.push_back(LI);
NumPRELoad++;
return true;
}
bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {
if (!MD)
return false;
if (L->isVolatile())
return false;
MemDepResult Dep = MD->getDependency(L);
if (Dep.isClobber()) {
Value *AvailVal = 0;
if (StoreInst *DepSI = dyn_cast<StoreInst>(Dep.getInst()))
if (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
int Offset = AnalyzeLoadFromClobberingStore(L->getType(),
L->getPointerOperand(),
DepSI, *TD);
if (Offset != -1)
AvailVal = GetStoreValueForLoad(DepSI->getOperand(0), Offset,
L->getType(), L, *TD);
}
if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(Dep.getInst())) {
if (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
int Offset = AnalyzeLoadFromClobberingMemInst(L->getType(),
L->getPointerOperand(),
DepMI, *TD);
if (Offset != -1)
AvailVal = GetMemInstValueForLoad(DepMI, Offset, L->getType(), L,*TD);
}
}
if (AvailVal) {
DEBUG(dbgs() << "GVN COERCED INST:\n" << *Dep.getInst() << '\n'
<< *AvailVal << '\n' << *L << "\n\n\n");
L->replaceAllUsesWith(AvailVal);
if (AvailVal->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(AvailVal);
VN.erase(L);
toErase.push_back(L);
NumGVNLoad++;
return true;
}
DEBUG(
dbgs() << "GVN: load ";
WriteAsOperand(dbgs(), L);
Instruction *I = Dep.getInst();
dbgs() << " is clobbered by " << *I << '\n';
);
return false;
}
if (Dep.isNonLocal())
return processNonLocalLoad(L, toErase);
Instruction *DepInst = Dep.getInst();
if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInst)) {
Value *StoredVal = DepSI->getOperand(0);
const TargetData *TD = 0;
if (StoredVal->getType() != L->getType()) {
if ((TD = getAnalysisIfAvailable<TargetData>())) {
StoredVal = CoerceAvailableValueToLoadType(StoredVal, L->getType(),
L, *TD);
if (StoredVal == 0)
return false;
DEBUG(dbgs() << "GVN COERCED STORE:\n" << *DepSI << '\n' << *StoredVal
<< '\n' << *L << "\n\n\n");
}
else
return false;
}
L->replaceAllUsesWith(StoredVal);
if (StoredVal->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(StoredVal);
VN.erase(L);
toErase.push_back(L);
NumGVNLoad++;
return true;
}
if (LoadInst *DepLI = dyn_cast<LoadInst>(DepInst)) {
Value *AvailableVal = DepLI;
const TargetData *TD = 0;
if (DepLI->getType() != L->getType()) {
if ((TD = getAnalysisIfAvailable<TargetData>())) {
AvailableVal = CoerceAvailableValueToLoadType(DepLI, L->getType(), L,*TD);
if (AvailableVal == 0)
return false;
DEBUG(dbgs() << "GVN COERCED LOAD:\n" << *DepLI << "\n" << *AvailableVal
<< "\n" << *L << "\n\n\n");
}
else
return false;
}
L->replaceAllUsesWith(AvailableVal);
if (DepLI->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(DepLI);
VN.erase(L);
toErase.push_back(L);
NumGVNLoad++;
return true;
}
if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
VN.erase(L);
toErase.push_back(L);
NumGVNLoad++;
return true;
}
if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
VN.erase(L);
toErase.push_back(L);
NumGVNLoad++;
return true;
}
}
return false;
}
Value *GVN::lookupNumber(BasicBlock *BB, uint32_t num) {
DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
if (I == localAvail.end())
return 0;
ValueNumberScope *Locals = I->second;
while (Locals) {
DenseMap<uint32_t, Value*>::iterator I = Locals->table.find(num);
if (I != Locals->table.end())
return I->second;
Locals = Locals->parent;
}
return 0;
}
bool GVN::processInstruction(Instruction *I,
SmallVectorImpl<Instruction*> &toErase) {
if (isa<DbgInfoIntrinsic>(I))
return false;
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
bool Changed = processLoad(LI, toErase);
if (!Changed) {
unsigned Num = VN.lookup_or_add(LI);
localAvail[I->getParent()]->table.insert(std::make_pair(Num, LI));
}
return Changed;
}
uint32_t NextNum = VN.getNextUnusedValueNumber();
unsigned Num = VN.lookup_or_add(I);
if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
return false;
Value *BranchCond = BI->getCondition();
uint32_t CondVN = VN.lookup_or_add(BranchCond);
BasicBlock *TrueSucc = BI->getSuccessor(0);
BasicBlock *FalseSucc = BI->getSuccessor(1);
if (TrueSucc->getSinglePredecessor())
localAvail[TrueSucc]->table[CondVN] =
ConstantInt::getTrue(TrueSucc->getContext());
if (FalseSucc->getSinglePredecessor())
localAvail[FalseSucc]->table[CondVN] =
ConstantInt::getFalse(TrueSucc->getContext());
return false;
} else if (isa<AllocaInst>(I) || isa<TerminatorInst>(I)) {
localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
return false;
}
if (PHINode* p = dyn_cast<PHINode>(I)) {
Value *constVal = CollapsePhi(p);
if (constVal) {
p->replaceAllUsesWith(constVal);
if (MD && constVal->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(constVal);
VN.erase(p);
toErase.push_back(p);
} else {
localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
}
} else if (Num == NextNum) {
localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
} else if (Value *repl = lookupNumber(I->getParent(), Num)) {
VN.erase(I);
I->replaceAllUsesWith(repl);
if (MD && repl->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(repl);
toErase.push_back(I);
return true;
} else {
localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
}
return false;
}
bool GVN::runOnFunction(Function& F) {
if (!NoLoads)
MD = &getAnalysis<MemoryDependenceAnalysis>();
DT = &getAnalysis<DominatorTree>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
VN.setMemDep(MD);
VN.setDomTree(DT);
bool Changed = false;
bool ShouldContinue = true;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) {
BasicBlock *BB = FI;
++FI;
bool removedBlock = MergeBlockIntoPredecessor(BB, this);
if (removedBlock) NumGVNBlocks++;
Changed |= removedBlock;
}
unsigned Iteration = 0;
while (ShouldContinue) {
DEBUG(dbgs() << "GVN iteration: " << Iteration << "\n");
ShouldContinue = iterateOnFunction(F);
if (splitCriticalEdges())
ShouldContinue = true;
Changed |= ShouldContinue;
++Iteration;
}
if (EnablePRE) {
bool PREChanged = true;
while (PREChanged) {
PREChanged = performPRE(F);
Changed |= PREChanged;
}
}
cleanupGlobalSets();
return Changed;
}
bool GVN::processBlock(BasicBlock *BB) {
SmallVector<Instruction*, 8> toErase;
bool ChangedFunction = false;
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE;) {
ChangedFunction |= processInstruction(BI, toErase);
if (toErase.empty()) {
++BI;
continue;
}
NumGVNInstr += toErase.size();
bool AtStart = BI == BB->begin();
if (!AtStart)
--BI;
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
E = toErase.end(); I != E; ++I) {
DEBUG(dbgs() << "GVN removed: " << **I << '\n');
if (MD) MD->removeInstruction(*I);
(*I)->eraseFromParent();
DEBUG(verifyRemoved(*I));
}
toErase.clear();
if (AtStart)
BI = BB->begin();
else
++BI;
}
return ChangedFunction;
}
bool GVN::performPRE(Function &F) {
bool Changed = false;
DenseMap<BasicBlock*, Value*> predMap;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
BasicBlock *CurrentBlock = *DI;
if (CurrentBlock == &F.getEntryBlock()) continue;
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
Instruction *CurInst = BI++;
if (isa<AllocaInst>(CurInst) ||
isa<TerminatorInst>(CurInst) || isa<PHINode>(CurInst) ||
CurInst->getType()->isVoidTy() ||
CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
isa<DbgInfoIntrinsic>(CurInst))
continue;
uint32_t ValNo = VN.lookup(CurInst);
unsigned NumWith = 0;
unsigned NumWithout = 0;
BasicBlock *PREPred = 0;
predMap.clear();
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI) {
if (*PI == CurrentBlock) {
NumWithout = 2;
break;
} else if (!localAvail.count(*PI)) {
NumWithout = 2;
break;
}
DenseMap<uint32_t, Value*>::iterator predV =
localAvail[*PI]->table.find(ValNo);
if (predV == localAvail[*PI]->table.end()) {
PREPred = *PI;
NumWithout++;
} else if (predV->second == CurInst) {
NumWithout = 2;
} else {
predMap[*PI] = predV->second;
NumWith++;
}
}
if (NumWithout != 1 || NumWith == 0)
continue;
if (isa<IndirectBrInst>(PREPred->getTerminator()))
continue;
unsigned SuccNum = GetSuccessorNumber(PREPred, CurrentBlock);
if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
continue;
}
Instruction *PREInstr = CurInst->clone();
bool success = true;
for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
Value *Op = PREInstr->getOperand(i);
if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
continue;
if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
PREInstr->setOperand(i, V);
} else {
success = false;
break;
}
}
if (!success) {
delete PREInstr;
DEBUG(verifyRemoved(PREInstr));
continue;
}
PREInstr->insertBefore(PREPred->getTerminator());
PREInstr->setName(CurInst->getName() + ".pre");
predMap[PREPred] = PREInstr;
VN.add(PREInstr, ValNo);
NumGVNPRE++;
localAvail[PREPred]->table.insert(std::make_pair(ValNo, PREInstr));
PHINode* Phi = PHINode::Create(CurInst->getType(),
CurInst->getName() + ".pre-phi",
CurrentBlock->begin());
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI)
Phi->addIncoming(predMap[*PI], *PI);
VN.add(Phi, ValNo);
localAvail[CurrentBlock]->table[ValNo] = Phi;
CurInst->replaceAllUsesWith(Phi);
if (MD && Phi->getType()->isPointerTy())
MD->invalidateCachedPointerInfo(Phi);
VN.erase(CurInst);
DEBUG(dbgs() << "GVN PRE removed: " << *CurInst << '\n');
if (MD) MD->removeInstruction(CurInst);
CurInst->eraseFromParent();
DEBUG(verifyRemoved(CurInst));
Changed = true;
}
}
if (splitCriticalEdges())
Changed = true;
return Changed;
}
bool GVN::splitCriticalEdges() {
if (toSplit.empty())
return false;
do {
std::pair<TerminatorInst*, unsigned> Edge = toSplit.pop_back_val();
SplitCriticalEdge(Edge.first, Edge.second, this);
} while (!toSplit.empty());
if (MD) MD->invalidateCachedPredecessors();
return true;
}
bool GVN::iterateOnFunction(Function &F) {
cleanupGlobalSets();
for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
DE = df_end(DT->getRootNode()); DI != DE; ++DI) {
if (DI->getIDom())
localAvail[DI->getBlock()] =
new ValueNumberScope(localAvail[DI->getIDom()->getBlock()]);
else
localAvail[DI->getBlock()] = new ValueNumberScope(0);
}
bool Changed = false;
#if 0
ReversePostOrderTraversal<Function*> RPOT(&F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator RI = RPOT.begin(),
RE = RPOT.end(); RI != RE; ++RI)
Changed |= processBlock(*RI);
#else
for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
DE = df_end(DT->getRootNode()); DI != DE; ++DI)
Changed |= processBlock(DI->getBlock());
#endif
return Changed;
}
void GVN::cleanupGlobalSets() {
VN.clear();
for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
delete I->second;
localAvail.clear();
}
void GVN::verifyRemoved(const Instruction *Inst) const {
VN.verifyRemoved(Inst);
for (DenseMap<BasicBlock*, ValueNumberScope*>::const_iterator
I = localAvail.begin(), E = localAvail.end(); I != E; ++I) {
const ValueNumberScope *VNS = I->second;
while (VNS) {
for (DenseMap<uint32_t, Value*>::const_iterator
II = VNS->table.begin(), IE = VNS->table.end(); II != IE; ++II) {
assert(II->second != Inst && "Inst still in value numbering scope!");
}
VNS = VNS->parent;
}
}
}