#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/CtorUtils.h"
#include "llvm/Transforms/Utils/GlobalStatus.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include <algorithm>
#include <deque>
using namespace llvm;
#define DEBUG_TYPE "globalopt"
STATISTIC(NumMarked , "Number of globals marked constant");
STATISTIC(NumUnnamed , "Number of globals marked unnamed_addr");
STATISTIC(NumSRA , "Number of aggregate globals broken into scalars");
STATISTIC(NumHeapSRA , "Number of heap objects SRA'd");
STATISTIC(NumSubstitute,"Number of globals with initializers stored into them");
STATISTIC(NumDeleted , "Number of globals deleted");
STATISTIC(NumFnDeleted , "Number of functions deleted");
STATISTIC(NumGlobUses , "Number of global uses devirtualized");
STATISTIC(NumLocalized , "Number of globals localized");
STATISTIC(NumShrunkToBool , "Number of global vars shrunk to booleans");
STATISTIC(NumFastCallFns , "Number of functions converted to fastcc");
STATISTIC(NumCtorsEvaluated, "Number of static ctors evaluated");
STATISTIC(NumNestRemoved , "Number of nest attributes removed");
STATISTIC(NumAliasesResolved, "Number of global aliases resolved");
STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated");
STATISTIC(NumCXXDtorsRemoved, "Number of global C++ destructors removed");
namespace {
struct GlobalOpt : public ModulePass {
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
static char ID; GlobalOpt() : ModulePass(ID) {
initializeGlobalOptPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override;
private:
bool OptimizeFunctions(Module &M);
bool OptimizeGlobalVars(Module &M);
bool OptimizeGlobalAliases(Module &M);
bool ProcessGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI,
const GlobalStatus &GS);
bool OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn);
TargetLibraryInfo *TLI;
SmallSet<const Comdat *, 8> NotDiscardableComdats;
};
}
char GlobalOpt::ID = 0;
INITIALIZE_PASS_BEGIN(GlobalOpt, "globalopt",
"Global Variable Optimizer", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(GlobalOpt, "globalopt",
"Global Variable Optimizer", false, false)
ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
static bool isLeakCheckerRoot(GlobalVariable *GV) {
if (GV->hasPrivateLinkage())
return false;
SmallVector<Type *, 4> Types;
Types.push_back(cast<PointerType>(GV->getType())->getElementType());
unsigned Limit = 20;
do {
Type *Ty = Types.pop_back_val();
switch (Ty->getTypeID()) {
default: break;
case Type::PointerTyID: return true;
case Type::ArrayTyID:
case Type::VectorTyID: {
SequentialType *STy = cast<SequentialType>(Ty);
Types.push_back(STy->getElementType());
break;
}
case Type::StructTyID: {
StructType *STy = cast<StructType>(Ty);
if (STy->isOpaque()) return true;
for (StructType::element_iterator I = STy->element_begin(),
E = STy->element_end(); I != E; ++I) {
Type *InnerTy = *I;
if (isa<PointerType>(InnerTy)) return true;
if (isa<CompositeType>(InnerTy))
Types.push_back(InnerTy);
}
break;
}
}
if (--Limit == 0) return true;
} while (!Types.empty());
return false;
}
static bool IsSafeComputationToRemove(Value *V, const TargetLibraryInfo *TLI) {
do {
if (isa<Constant>(V))
return true;
if (!V->hasOneUse())
return false;
if (isa<LoadInst>(V) || isa<InvokeInst>(V) || isa<Argument>(V) ||
isa<GlobalValue>(V))
return false;
if (isAllocationFn(V, TLI))
return true;
Instruction *I = cast<Instruction>(V);
if (I->mayHaveSideEffects())
return false;
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
if (!GEP->hasAllConstantIndices())
return false;
} else if (I->getNumOperands() != 1) {
return false;
}
V = I->getOperand(0);
} while (1);
}
static bool CleanupPointerRootUsers(GlobalVariable *GV,
const TargetLibraryInfo *TLI) {
bool Changed = false;
SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead;
for (Value::user_iterator UI = GV->user_begin(), E = GV->user_end();
UI != E;) {
User *U = *UI++;
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
Value *V = SI->getValueOperand();
if (isa<Constant>(V)) {
Changed = true;
SI->eraseFromParent();
} else if (Instruction *I = dyn_cast<Instruction>(V)) {
if (I->hasOneUse())
Dead.push_back(std::make_pair(I, SI));
}
} else if (MemSetInst *MSI = dyn_cast<MemSetInst>(U)) {
if (isa<Constant>(MSI->getValue())) {
Changed = true;
MSI->eraseFromParent();
} else if (Instruction *I = dyn_cast<Instruction>(MSI->getValue())) {
if (I->hasOneUse())
Dead.push_back(std::make_pair(I, MSI));
}
} else if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U)) {
GlobalVariable *MemSrc = dyn_cast<GlobalVariable>(MTI->getSource());
if (MemSrc && MemSrc->isConstant()) {
Changed = true;
MTI->eraseFromParent();
} else if (Instruction *I = dyn_cast<Instruction>(MemSrc)) {
if (I->hasOneUse())
Dead.push_back(std::make_pair(I, MTI));
}
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->use_empty()) {
CE->destroyConstant();
Changed = true;
}
} else if (Constant *C = dyn_cast<Constant>(U)) {
if (isSafeToDestroyConstant(C)) {
C->destroyConstant();
Dead.clear();
CleanupPointerRootUsers(GV, TLI);
return true;
}
}
}
for (int i = 0, e = Dead.size(); i != e; ++i) {
if (IsSafeComputationToRemove(Dead[i].first, TLI)) {
Dead[i].second->eraseFromParent();
Instruction *I = Dead[i].first;
do {
if (isAllocationFn(I, TLI))
break;
Instruction *J = dyn_cast<Instruction>(I->getOperand(0));
if (!J)
break;
I->eraseFromParent();
I = J;
} while (1);
I->eraseFromParent();
}
}
return Changed;
}
static bool CleanupConstantGlobalUsers(Value *V, Constant *Init,
const DataLayout &DL,
TargetLibraryInfo *TLI) {
bool Changed = false;
SmallVector<WeakVH, 8> WorkList(V->user_begin(), V->user_end());
while (!WorkList.empty()) {
Value *UV = WorkList.pop_back_val();
if (!UV)
continue;
User *U = cast<User>(UV);
if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
if (Init) {
LI->replaceAllUsesWith(Init);
LI->eraseFromParent();
Changed = true;
}
} else if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
SI->eraseFromParent();
Changed = true;
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
Constant *SubInit = nullptr;
if (Init)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
Changed |= CleanupConstantGlobalUsers(CE, SubInit, DL, TLI);
} else if ((CE->getOpcode() == Instruction::BitCast &&
CE->getType()->isPointerTy()) ||
CE->getOpcode() == Instruction::AddrSpaceCast) {
Changed |= CleanupConstantGlobalUsers(CE, nullptr, DL, TLI);
}
if (CE->use_empty()) {
CE->destroyConstant();
Changed = true;
}
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
Constant *SubInit = nullptr;
if (!isa<ConstantExpr>(GEP->getOperand(0))) {
ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(
ConstantFoldInstruction(GEP, DL, TLI));
if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr)
SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE);
if (Init && isa<ConstantAggregateZero>(Init) && GEP->isInBounds())
SubInit = Constant::getNullValue(GEP->getType()->getElementType());
}
Changed |= CleanupConstantGlobalUsers(GEP, SubInit, DL, TLI);
if (GEP->use_empty()) {
GEP->eraseFromParent();
Changed = true;
}
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U)) { if (MI->getRawDest() == V) {
MI->eraseFromParent();
Changed = true;
}
} else if (Constant *C = dyn_cast<Constant>(U)) {
if (isSafeToDestroyConstant(C)) {
C->destroyConstant();
CleanupConstantGlobalUsers(V, Init, DL, TLI);
return true;
}
}
}
return Changed;
}
static bool isSafeSROAElementUse(Value *V) {
if (Constant *C = dyn_cast<Constant>(V))
return isSafeToDestroyConstant(C);
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false;
if (isa<LoadInst>(I)) return true;
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return SI->getOperand(0) != V;
GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I);
if (!GEPI) return false;
if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) ||
!cast<Constant>(GEPI->getOperand(1))->isNullValue())
return false;
for (User *U : GEPI->users())
if (!isSafeSROAElementUse(U))
return false;
return true;
}
static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) {
if (!isa<GetElementPtrInst>(U) &&
(!isa<ConstantExpr>(U) ||
cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr))
return false;
if (U->getNumOperands() < 3 || !isa<Constant>(U->getOperand(1)) ||
!cast<Constant>(U->getOperand(1))->isNullValue() ||
!isa<ConstantInt>(U->getOperand(2)))
return false;
gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U);
++GEPI;
if (ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) {
uint64_t NumElements = AT->getNumElements();
ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2));
if (Idx->getZExtValue() >= NumElements)
return false;
for (++GEPI; GEPI != E;
++GEPI) {
uint64_t NumElements;
if (ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI))
NumElements = SubArrayTy->getNumElements();
else if (VectorType *SubVectorTy = dyn_cast<VectorType>(*GEPI))
NumElements = SubVectorTy->getNumElements();
else {
assert((*GEPI)->isStructTy() &&
"Indexed GEP type is not array, vector, or struct!");
continue;
}
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand());
if (!IdxVal || IdxVal->getZExtValue() >= NumElements)
return false;
}
}
for (User *UU : U->users())
if (!isSafeSROAElementUse(UU))
return false;
return true;
}
static bool GlobalUsersSafeToSRA(GlobalValue *GV) {
for (User *U : GV->users())
if (!IsUserOfGlobalSafeForSRA(U, GV))
return false;
return true;
}
static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
if (!GlobalUsersSafeToSRA(GV))
return nullptr;
assert(GV->hasLocalLinkage() && !GV->isConstant());
Constant *Init = GV->getInitializer();
Type *Ty = Init->getType();
std::vector<GlobalVariable*> NewGlobals;
Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
unsigned StartAlignment = GV->getAlignment();
if (StartAlignment == 0)
StartAlignment = DL.getABITypeAlignment(GV->getType());
if (StructType *STy = dyn_cast<StructType>(Ty)) {
NewGlobals.reserve(STy->getNumElements());
const StructLayout &Layout = *DL.getStructLayout(STy);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Constant *In = Init->getAggregateElement(i);
assert(In && "Couldn't get element of initializer?");
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+Twine(i),
GV->getThreadLocalMode(),
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
uint64_t FieldOffset = Layout.getElementOffset(i);
unsigned NewAlign = (unsigned)MinAlign(StartAlignment, FieldOffset);
if (NewAlign > DL.getABITypeAlignment(STy->getElementType(i)))
NGV->setAlignment(NewAlign);
}
} else if (SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
unsigned NumElements = 0;
if (ArrayType *ATy = dyn_cast<ArrayType>(STy))
NumElements = ATy->getNumElements();
else
NumElements = cast<VectorType>(STy)->getNumElements();
if (NumElements > 16 && GV->hasNUsesOrMore(16))
return nullptr; NewGlobals.reserve(NumElements);
uint64_t EltSize = DL.getTypeAllocSize(STy->getElementType());
unsigned EltAlign = DL.getABITypeAlignment(STy->getElementType());
for (unsigned i = 0, e = NumElements; i != e; ++i) {
Constant *In = Init->getAggregateElement(i);
assert(In && "Couldn't get element of initializer?");
GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false,
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+Twine(i),
GV->getThreadLocalMode(),
GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i);
if (NewAlign > EltAlign)
NGV->setAlignment(NewAlign);
}
}
if (NewGlobals.empty())
return nullptr;
DEBUG(dbgs() << "PERFORMING GLOBAL SRA ON: " << *GV);
Constant *NullInt =Constant::getNullValue(Type::getInt32Ty(GV->getContext()));
while (!GV->use_empty()) {
User *GEP = GV->user_back();
assert(((isa<ConstantExpr>(GEP) &&
cast<ConstantExpr>(GEP)->getOpcode()==Instruction::GetElementPtr)||
isa<GetElementPtrInst>(GEP)) && "NonGEP CE's are not SRAable!");
unsigned Val = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
if (Val >= NewGlobals.size()) Val = 0;
Value *NewPtr = NewGlobals[Val];
if (GEP->getNumOperands() > 3) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP)) {
SmallVector<Constant*, 8> Idxs;
Idxs.push_back(NullInt);
for (unsigned i = 3, e = CE->getNumOperands(); i != e; ++i)
Idxs.push_back(CE->getOperand(i));
NewPtr = ConstantExpr::getGetElementPtr(cast<Constant>(NewPtr), Idxs);
} else {
GetElementPtrInst *GEPI = cast<GetElementPtrInst>(GEP);
SmallVector<Value*, 8> Idxs;
Idxs.push_back(NullInt);
for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i)
Idxs.push_back(GEPI->getOperand(i));
NewPtr = GetElementPtrInst::Create(NewPtr, Idxs,
GEPI->getName()+"."+Twine(Val),GEPI);
}
}
GEP->replaceAllUsesWith(NewPtr);
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(GEP))
GEPI->eraseFromParent();
else
cast<ConstantExpr>(GEP)->destroyConstant();
}
Globals.erase(GV);
++NumSRA;
unsigned FirstGlobal = 0;
for (unsigned i = 0, e = NewGlobals.size(); i != e; ++i)
if (NewGlobals[i]->use_empty()) {
Globals.erase(NewGlobals[i]);
if (FirstGlobal == i) ++FirstGlobal;
}
return FirstGlobal != NewGlobals.size() ? NewGlobals[FirstGlobal] : nullptr;
}
static bool AllUsesOfValueWillTrapIfNull(const Value *V,
SmallPtrSetImpl<const PHINode*> &PHIs) {
for (const User *U : V->users())
if (isa<LoadInst>(U)) {
} else if (const StoreInst *SI = dyn_cast<StoreInst>(U)) {
if (SI->getOperand(0) == V) {
return false; }
} else if (const CallInst *CI = dyn_cast<CallInst>(U)) {
if (CI->getCalledValue() != V) {
return false; }
} else if (const InvokeInst *II = dyn_cast<InvokeInst>(U)) {
if (II->getCalledValue() != V) {
return false; }
} else if (const BitCastInst *CI = dyn_cast<BitCastInst>(U)) {
if (!AllUsesOfValueWillTrapIfNull(CI, PHIs)) return false;
} else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) {
if (!AllUsesOfValueWillTrapIfNull(GEPI, PHIs)) return false;
} else if (const PHINode *PN = dyn_cast<PHINode>(U)) {
if (PHIs.insert(PN).second && !AllUsesOfValueWillTrapIfNull(PN, PHIs))
return false;
} else if (isa<ICmpInst>(U) &&
isa<ConstantPointerNull>(U->getOperand(1))) {
} else {
return false;
}
return true;
}
static bool AllUsesOfLoadedValueWillTrapIfNull(const GlobalVariable *GV) {
for (const User *U : GV->users())
if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {
SmallPtrSet<const PHINode*, 8> PHIs;
if (!AllUsesOfValueWillTrapIfNull(LI, PHIs))
return false;
} else if (isa<StoreInst>(U)) {
} else {
return false;
}
return true;
}
static bool OptimizeAwayTrappingUsesOfValue(Value *V, Constant *NewV) {
bool Changed = false;
for (auto UI = V->user_begin(), E = V->user_end(); UI != E; ) {
Instruction *I = cast<Instruction>(*UI++);
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
LI->setOperand(0, NewV);
Changed = true;
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (SI->getOperand(1) == V) {
SI->setOperand(1, NewV);
Changed = true;
}
} else if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
CallSite CS(I);
if (CS.getCalledValue() == V) {
CS.setCalledFunction(NewV);
Changed = true;
bool PassedAsArg = false;
for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
if (CS.getArgument(i) == V) {
PassedAsArg = true;
CS.setArgument(i, NewV);
}
if (PassedAsArg) {
UI = V->user_begin();
}
}
} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
Changed |= OptimizeAwayTrappingUsesOfValue(CI,
ConstantExpr::getCast(CI->getOpcode(),
NewV, CI->getType()));
if (CI->use_empty()) {
Changed = true;
CI->eraseFromParent();
}
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
SmallVector<Constant*, 8> Idxs;
Idxs.reserve(GEPI->getNumOperands()-1);
for (User::op_iterator i = GEPI->op_begin() + 1, e = GEPI->op_end();
i != e; ++i)
if (Constant *C = dyn_cast<Constant>(*i))
Idxs.push_back(C);
else
break;
if (Idxs.size() == GEPI->getNumOperands()-1)
Changed |= OptimizeAwayTrappingUsesOfValue(GEPI,
ConstantExpr::getGetElementPtr(NewV, Idxs));
if (GEPI->use_empty()) {
Changed = true;
GEPI->eraseFromParent();
}
}
}
return Changed;
}
static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV,
const DataLayout &DL,
TargetLibraryInfo *TLI) {
bool Changed = false;
bool AllNonStoreUsesGone = true;
for (Value::user_iterator GUI = GV->user_begin(), E = GV->user_end(); GUI != E;){
User *GlobalUser = *GUI++;
if (LoadInst *LI = dyn_cast<LoadInst>(GlobalUser)) {
Changed |= OptimizeAwayTrappingUsesOfValue(LI, LV);
if (LI->use_empty()) {
LI->eraseFromParent();
Changed = true;
} else {
AllNonStoreUsesGone = false;
}
} else if (isa<StoreInst>(GlobalUser)) {
assert(GlobalUser->getOperand(1) == GV &&
"Must be storing *to* the global");
} else {
AllNonStoreUsesGone = false;
assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser) ||
isa<BitCastInst>(GlobalUser) ||
isa<GetElementPtrInst>(GlobalUser)) &&
"Only expect load and stores!");
}
}
if (Changed) {
DEBUG(dbgs() << "OPTIMIZED LOADS FROM STORED ONCE POINTER: " << *GV);
++NumGlobUses;
}
if (AllNonStoreUsesGone) {
if (isLeakCheckerRoot(GV)) {
Changed |= CleanupPointerRootUsers(GV, TLI);
} else {
Changed = true;
CleanupConstantGlobalUsers(GV, nullptr, DL, TLI);
}
if (GV->use_empty()) {
DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
Changed = true;
GV->eraseFromParent();
++NumDeleted;
}
}
return Changed;
}
static void ConstantPropUsersOf(Value *V, const DataLayout &DL,
TargetLibraryInfo *TLI) {
for (Value::user_iterator UI = V->user_begin(), E = V->user_end(); UI != E; )
if (Instruction *I = dyn_cast<Instruction>(*UI++))
if (Constant *NewC = ConstantFoldInstruction(I, DL, TLI)) {
I->replaceAllUsesWith(NewC);
while (UI != E && *UI == I)
++UI;
I->eraseFromParent();
}
}
static GlobalVariable *
OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, CallInst *CI, Type *AllocTy,
ConstantInt *NElements, const DataLayout &DL,
TargetLibraryInfo *TLI) {
DEBUG(errs() << "PROMOTING GLOBAL: " << *GV << " CALL = " << *CI << '\n');
Type *GlobalType;
if (NElements->getZExtValue() == 1)
GlobalType = AllocTy;
else
GlobalType = ArrayType::get(AllocTy, NElements->getZExtValue());
GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(),
GlobalType, false,
GlobalValue::InternalLinkage,
UndefValue::get(GlobalType),
GV->getName()+".body",
GV,
GV->getThreadLocalMode());
BitCastInst *TheBC = nullptr;
while (!CI->use_empty()) {
Instruction *User = cast<Instruction>(CI->user_back());
if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
if (BCI->getType() == NewGV->getType()) {
BCI->replaceAllUsesWith(NewGV);
BCI->eraseFromParent();
} else {
BCI->setOperand(0, NewGV);
}
} else {
if (!TheBC)
TheBC = new BitCastInst(NewGV, CI->getType(), "newgv", CI);
User->replaceUsesOfWith(CI, TheBC);
}
}
Constant *RepValue = NewGV;
if (NewGV->getType() != GV->getType()->getElementType())
RepValue = ConstantExpr::getBitCast(RepValue,
GV->getType()->getElementType());
GlobalVariable *InitBool =
new GlobalVariable(Type::getInt1Ty(GV->getContext()), false,
GlobalValue::InternalLinkage,
ConstantInt::getFalse(GV->getContext()),
GV->getName()+".init", GV->getThreadLocalMode());
bool InitBoolUsed = false;
while (!GV->use_empty()) {
if (StoreInst *SI = dyn_cast<StoreInst>(GV->user_back())) {
new StoreInst(ConstantInt::getTrue(GV->getContext()), InitBool, false, 0,
SI->getOrdering(), SI->getSynchScope(), SI);
SI->eraseFromParent();
continue;
}
LoadInst *LI = cast<LoadInst>(GV->user_back());
while (!LI->use_empty()) {
Use &LoadUse = *LI->use_begin();
ICmpInst *ICI = dyn_cast<ICmpInst>(LoadUse.getUser());
if (!ICI) {
LoadUse = RepValue;
continue;
}
Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", false, 0,
LI->getOrdering(), LI->getSynchScope(),
LI->isUnordered() ? (Instruction*)ICI : LI);
InitBoolUsed = true;
switch (ICI->getPredicate()) {
default: llvm_unreachable("Unknown ICmp Predicate!");
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT: LV = ConstantInt::getFalse(GV->getContext());
break;
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE:
case ICmpInst::ICMP_EQ:
LV = BinaryOperator::CreateNot(LV, "notinit", ICI);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT:
break; }
ICI->replaceAllUsesWith(LV);
ICI->eraseFromParent();
}
LI->eraseFromParent();
}
if (!InitBoolUsed) {
while (!InitBool->use_empty()) cast<StoreInst>(InitBool->user_back())->eraseFromParent();
delete InitBool;
} else
GV->getParent()->getGlobalList().insert(GV, InitBool);
GV->eraseFromParent();
CI->eraseFromParent();
ConstantPropUsersOf(NewGV, DL, TLI);
if (RepValue != NewGV)
ConstantPropUsersOf(RepValue, DL, TLI);
return NewGV;
}
static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(const Instruction *V,
const GlobalVariable *GV,
SmallPtrSetImpl<const PHINode*> &PHIs) {
for (const User *U : V->users()) {
const Instruction *Inst = cast<Instruction>(U);
if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) {
continue; }
if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
return false; continue; }
if (isa<GetElementPtrInst>(Inst) && Inst->getNumOperands() >= 3) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs))
return false;
continue;
}
if (const PHINode *PN = dyn_cast<PHINode>(Inst)) {
if (PHIs.insert(PN).second)
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(PN, GV, PHIs))
return false;
continue;
}
if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) {
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs))
return false;
continue;
}
return false;
}
return true;
}
static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
GlobalVariable *GV) {
while (!Alloc->use_empty()) {
Instruction *U = cast<Instruction>(*Alloc->user_begin());
Instruction *InsertPt = U;
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
if (SI->getOperand(1) == GV) {
SI->eraseFromParent();
continue;
}
} else if (PHINode *PN = dyn_cast<PHINode>(U)) {
InsertPt = PN->getIncomingBlock(*Alloc->use_begin())->getTerminator();
} else if (isa<BitCastInst>(U)) {
ReplaceUsesOfMallocWithGlobal(U, GV);
U->eraseFromParent();
continue;
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) {
if (GEPI->hasAllZeroIndices() && GEPI->hasOneUse())
if (StoreInst *SI = dyn_cast<StoreInst>(GEPI->user_back()))
if (SI->getOperand(1) == GV) {
ReplaceUsesOfMallocWithGlobal(GEPI, GV);
GEPI->eraseFromParent();
continue;
}
}
Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt);
U->replaceUsesOfWith(Alloc, NL);
}
}
static bool LoadUsesSimpleEnoughForHeapSRA(const Value *V,
SmallPtrSetImpl<const PHINode*> &LoadUsingPHIs,
SmallPtrSetImpl<const PHINode*> &LoadUsingPHIsPerLoad) {
for (const User *U : V->users()) {
const Instruction *UI = cast<Instruction>(U);
if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UI)) {
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
return false;
continue;
}
if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(UI)) {
if (GEPI->getNumOperands() < 3)
return false;
continue;
}
if (const PHINode *PN = dyn_cast<PHINode>(UI)) {
if (!LoadUsingPHIsPerLoad.insert(PN).second)
return false;
if (!LoadUsingPHIs.insert(PN).second)
continue;
if (!LoadUsesSimpleEnoughForHeapSRA(PN,
LoadUsingPHIs, LoadUsingPHIsPerLoad))
return false;
continue;
}
return false;
}
return true;
}
static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(const GlobalVariable *GV,
Instruction *StoredVal) {
SmallPtrSet<const PHINode*, 32> LoadUsingPHIs;
SmallPtrSet<const PHINode*, 32> LoadUsingPHIsPerLoad;
for (const User *U : GV->users())
if (const LoadInst *LI = dyn_cast<LoadInst>(U)) {
if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs,
LoadUsingPHIsPerLoad))
return false;
LoadUsingPHIsPerLoad.clear();
}
for (const PHINode *PN : LoadUsingPHIs) {
for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) {
Value *InVal = PN->getIncomingValue(op);
if (InVal == StoredVal) continue;
if (const PHINode *InPN = dyn_cast<PHINode>(InVal)) {
if (LoadUsingPHIs.count(InPN))
continue;
return false;
}
if (const LoadInst *LI = dyn_cast<LoadInst>(InVal))
if (LI->getOperand(0) == GV)
continue;
return false;
}
}
return true;
}
static Value *GetHeapSROAValue(Value *V, unsigned FieldNo,
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
std::vector<Value*> &FieldVals = InsertedScalarizedValues[V];
if (FieldNo >= FieldVals.size())
FieldVals.resize(FieldNo+1);
if (Value *FieldVal = FieldVals[FieldNo])
return FieldVal;
Value *Result;
if (LoadInst *LI = dyn_cast<LoadInst>(V)) {
Result = new LoadInst(GetHeapSROAValue(LI->getOperand(0), FieldNo,
InsertedScalarizedValues,
PHIsToRewrite),
LI->getName()+".f"+Twine(FieldNo), LI);
} else if (PHINode *PN = dyn_cast<PHINode>(V)) {
PointerType *PTy = cast<PointerType>(PN->getType());
StructType *ST = cast<StructType>(PTy->getElementType());
unsigned AS = PTy->getAddressSpace();
PHINode *NewPN =
PHINode::Create(PointerType::get(ST->getElementType(FieldNo), AS),
PN->getNumIncomingValues(),
PN->getName()+".f"+Twine(FieldNo), PN);
Result = NewPN;
PHIsToRewrite.push_back(std::make_pair(PN, FieldNo));
} else {
llvm_unreachable("Unknown usable value");
}
return FieldVals[FieldNo] = Result;
}
static void RewriteHeapSROALoadUser(Instruction *LoadUser,
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
if (ICmpInst *SCI = dyn_cast<ICmpInst>(LoadUser)) {
assert(isa<ConstantPointerNull>(SCI->getOperand(1)));
Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0,
InsertedScalarizedValues, PHIsToRewrite);
Value *New = new ICmpInst(SCI, SCI->getPredicate(), NPtr,
Constant::getNullValue(NPtr->getType()),
SCI->getName());
SCI->replaceAllUsesWith(New);
SCI->eraseFromParent();
return;
}
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) {
assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2))
&& "Unexpected GEPI!");
unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo,
InsertedScalarizedValues, PHIsToRewrite);
SmallVector<Value*, 8> GEPIdx;
GEPIdx.push_back(GEPI->getOperand(1));
GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end());
Value *NGEPI = GetElementPtrInst::Create(NewPtr, GEPIdx,
GEPI->getName(), GEPI);
GEPI->replaceAllUsesWith(NGEPI);
GEPI->eraseFromParent();
return;
}
PHINode *PN = cast<PHINode>(LoadUser);
if (!InsertedScalarizedValues.insert(std::make_pair(PN,
std::vector<Value*>())).second)
return;
for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
}
}
static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load,
DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
for (auto UI = Load->user_begin(), E = Load->user_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
}
if (Load->use_empty()) {
Load->eraseFromParent();
InsertedScalarizedValues.erase(Load);
}
}
static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI,
Value *NElems, const DataLayout &DL,
const TargetLibraryInfo *TLI) {
DEBUG(dbgs() << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *CI << '\n');
Type *MAT = getMallocAllocatedType(CI, TLI);
StructType *STy = cast<StructType>(MAT);
ReplaceUsesOfMallocWithGlobal(CI, GV);
std::vector<Value*> FieldGlobals;
std::vector<Value*> FieldMallocs;
unsigned AS = GV->getType()->getPointerAddressSpace();
for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){
Type *FieldTy = STy->getElementType(FieldNo);
PointerType *PFieldTy = PointerType::get(FieldTy, AS);
GlobalVariable *NGV =
new GlobalVariable(*GV->getParent(),
PFieldTy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(PFieldTy),
GV->getName() + ".f" + Twine(FieldNo), GV,
GV->getThreadLocalMode());
FieldGlobals.push_back(NGV);
unsigned TypeSize = DL.getTypeAllocSize(FieldTy);
if (StructType *ST = dyn_cast<StructType>(FieldTy))
TypeSize = DL.getStructLayout(ST)->getSizeInBytes();
Type *IntPtrTy = DL.getIntPtrType(CI->getType());
Value *NMI = CallInst::CreateMalloc(CI, IntPtrTy, FieldTy,
ConstantInt::get(IntPtrTy, TypeSize),
NElems, nullptr,
CI->getName() + ".f" + Twine(FieldNo));
FieldMallocs.push_back(NMI);
new StoreInst(NMI, NGV, CI);
}
Constant *ConstantZero = ConstantInt::get(CI->getArgOperand(0)->getType(), 0);
Value *RunningOr = new ICmpInst(CI, ICmpInst::ICMP_SLT, CI->getArgOperand(0),
ConstantZero, "isneg");
for (unsigned i = 0, e = FieldMallocs.size(); i != e; ++i) {
Value *Cond = new ICmpInst(CI, ICmpInst::ICMP_EQ, FieldMallocs[i],
Constant::getNullValue(FieldMallocs[i]->getType()),
"isnull");
RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", CI);
}
BasicBlock *OrigBB = CI->getParent();
BasicBlock *ContBB = OrigBB->splitBasicBlock(CI, "malloc_cont");
BasicBlock *NullPtrBlock = BasicBlock::Create(OrigBB->getContext(),
"malloc_ret_null",
OrigBB->getParent());
OrigBB->getTerminator()->eraseFromParent();
BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB);
for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
Value *GVVal = new LoadInst(FieldGlobals[i], "tmp", NullPtrBlock);
Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal,
Constant::getNullValue(GVVal->getType()));
BasicBlock *FreeBlock = BasicBlock::Create(Cmp->getContext(), "free_it",
OrigBB->getParent());
BasicBlock *NextBlock = BasicBlock::Create(Cmp->getContext(), "next",
OrigBB->getParent());
Instruction *BI = BranchInst::Create(FreeBlock, NextBlock,
Cmp, NullPtrBlock);
CallInst::CreateFree(GVVal, BI);
new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i],
FreeBlock);
BranchInst::Create(NextBlock, FreeBlock);
NullPtrBlock = NextBlock;
}
BranchInst::Create(ContBB, NullPtrBlock);
CI->eraseFromParent();
DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues;
InsertedScalarizedValues[GV] = FieldGlobals;
std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite;
for (auto UI = GV->user_begin(), E = GV->user_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite);
continue;
}
StoreInst *SI = cast<StoreInst>(User);
assert(isa<ConstantPointerNull>(SI->getOperand(0)) &&
"Unexpected heap-sra user!");
for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType());
Constant *Null = Constant::getNullValue(PT->getElementType());
new StoreInst(Null, FieldGlobals[i], SI);
}
SI->eraseFromParent();
}
while (!PHIsToRewrite.empty()) {
PHINode *PN = PHIsToRewrite.back().first;
unsigned FieldNo = PHIsToRewrite.back().second;
PHIsToRewrite.pop_back();
PHINode *FieldPN = cast<PHINode>(InsertedScalarizedValues[PN][FieldNo]);
assert(FieldPN->getNumIncomingValues() == 0 &&"Already processed this phi");
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *InVal = PN->getIncomingValue(i);
InVal = GetHeapSROAValue(InVal, FieldNo, InsertedScalarizedValues,
PHIsToRewrite);
FieldPN->addIncoming(InVal, PN->getIncomingBlock(i));
}
}
for (DenseMap<Value*, std::vector<Value*> >::iterator
I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
I != E; ++I) {
if (PHINode *PN = dyn_cast<PHINode>(I->first))
PN->dropAllReferences();
else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
LI->dropAllReferences();
}
for (DenseMap<Value*, std::vector<Value*> >::iterator
I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end();
I != E; ++I) {
if (PHINode *PN = dyn_cast<PHINode>(I->first))
PN->eraseFromParent();
else if (LoadInst *LI = dyn_cast<LoadInst>(I->first))
LI->eraseFromParent();
}
GV->eraseFromParent();
++NumHeapSRA;
return cast<GlobalVariable>(FieldGlobals[0]);
}
static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV, CallInst *CI,
Type *AllocTy,
AtomicOrdering Ordering,
Module::global_iterator &GVI,
const DataLayout &DL,
TargetLibraryInfo *TLI) {
if (!AllocTy->isSized())
return false;
if (!AllUsesOfLoadedValueWillTrapIfNull(GV))
return false;
SmallPtrSet<const PHINode*, 8> PHIs;
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(CI, GV, PHIs))
return false;
Value *NElems = getMallocArraySize(CI, DL, TLI, true);
if (!NElems)
return false;
if (ConstantInt *NElements = dyn_cast<ConstantInt>(NElems))
if (NElements->getZExtValue() * DL.getTypeAllocSize(AllocTy) < 2048) {
GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, DL, TLI);
return true;
}
if (Ordering != NotAtomic)
return false;
if (NElems == ConstantInt::get(CI->getArgOperand(0)->getType(), 1))
if (ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
AllocTy = AT->getElementType();
StructType *AllocSTy = dyn_cast<StructType>(AllocTy);
if (!AllocSTy)
return false;
if (AllocSTy->getNumElements() <= 16 && AllocSTy->getNumElements() != 0 &&
AllGlobalLoadUsesSimpleEnoughForHeapSRA(GV, CI)) {
if (ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI, TLI))) {
Type *IntPtrTy = DL.getIntPtrType(CI->getType());
unsigned TypeSize = DL.getStructLayout(AllocSTy)->getSizeInBytes();
Value *AllocSize = ConstantInt::get(IntPtrTy, TypeSize);
Value *NumElements = ConstantInt::get(IntPtrTy, AT->getNumElements());
Instruction *Malloc = CallInst::CreateMalloc(CI, IntPtrTy, AllocSTy,
AllocSize, NumElements,
nullptr, CI->getName());
Instruction *Cast = new BitCastInst(Malloc, CI->getType(), "tmp", CI);
CI->replaceAllUsesWith(Cast);
CI->eraseFromParent();
if (BitCastInst *BCI = dyn_cast<BitCastInst>(Malloc))
CI = cast<CallInst>(BCI->getOperand(0));
else
CI = cast<CallInst>(Malloc);
}
GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, DL, TLI, true),
DL, TLI);
return true;
}
return false;
}
static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
AtomicOrdering Ordering,
Module::global_iterator &GVI,
const DataLayout &DL,
TargetLibraryInfo *TLI) {
StoredOnceVal = StoredOnceVal->stripPointerCasts();
if (GV->getInitializer()->getType()->isPointerTy() &&
GV->getInitializer()->isNullValue()) {
if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) {
if (GV->getInitializer()->getType() != SOVC->getType())
SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType());
if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC, DL, TLI))
return true;
} else if (CallInst *CI = extractMallocCall(StoredOnceVal, TLI)) {
Type *MallocType = getMallocAllocatedType(CI, TLI);
if (MallocType &&
TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, Ordering, GVI,
DL, TLI))
return true;
}
}
return false;
}
static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
Type *GVElType = GV->getType()->getElementType();
if (GVElType == Type::getInt1Ty(GV->getContext()) ||
GVElType->isFloatingPointTy() ||
GVElType->isPointerTy() || GVElType->isVectorTy())
return false;
for (User *U : GV->users())
if (!isa<LoadInst>(U) && !isa<StoreInst>(U))
return false;
DEBUG(dbgs() << " *** SHRINKING TO BOOL: " << *GV);
GlobalVariable *NewGV = new GlobalVariable(Type::getInt1Ty(GV->getContext()),
false,
GlobalValue::InternalLinkage,
ConstantInt::getFalse(GV->getContext()),
GV->getName()+".b",
GV->getThreadLocalMode(),
GV->getType()->getAddressSpace());
GV->getParent()->getGlobalList().insert(GV, NewGV);
Constant *InitVal = GV->getInitializer();
assert(InitVal->getType() != Type::getInt1Ty(GV->getContext()) &&
"No reason to shrink to bool!");
bool IsOneZero = false;
if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal))
IsOneZero = InitVal->isNullValue() && CI->isOne();
while (!GV->use_empty()) {
Instruction *UI = cast<Instruction>(GV->user_back());
if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
bool StoringOther = SI->getOperand(0) == OtherVal;
Value *StoreVal;
if (StoringOther || SI->getOperand(0) == InitVal) {
StoreVal = ConstantInt::get(Type::getInt1Ty(GV->getContext()),
StoringOther);
} else {
Instruction *StoredVal = cast<Instruction>(SI->getOperand(0));
if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) {
assert(LI->getOperand(0) == GV && "Not a copy!");
StoreVal = new LoadInst(NewGV, LI->getName()+".b", false, 0,
LI->getOrdering(), LI->getSynchScope(), LI);
} else {
assert((isa<CastInst>(StoredVal) || isa<SelectInst>(StoredVal)) &&
"This is not a form that we understand!");
StoreVal = StoredVal->getOperand(0);
assert(isa<LoadInst>(StoreVal) && "Not a load of NewGV!");
}
}
new StoreInst(StoreVal, NewGV, false, 0,
SI->getOrdering(), SI->getSynchScope(), SI);
} else {
LoadInst *LI = cast<LoadInst>(UI);
LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", false, 0,
LI->getOrdering(), LI->getSynchScope(), LI);
Value *NSI;
if (IsOneZero)
NSI = new ZExtInst(NLI, LI->getType(), "", LI);
else
NSI = SelectInst::Create(NLI, OtherVal, InitVal, "", LI);
NSI->takeName(LI);
LI->replaceAllUsesWith(NSI);
}
UI->eraseFromParent();
}
NewGV->takeName(GV);
GV->eraseFromParent();
return true;
}
bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
Module::global_iterator &GVI) {
GV->removeDeadConstantUsers();
if (GV->use_empty()) {
DEBUG(dbgs() << "GLOBAL DEAD: " << *GV);
GV->eraseFromParent();
++NumDeleted;
return true;
}
if (!GV->hasLocalLinkage())
return false;
GlobalStatus GS;
if (GlobalStatus::analyzeGlobal(GV, GS))
return false;
if (!GS.IsCompared && !GV->hasUnnamedAddr()) {
GV->setUnnamedAddr(true);
NumUnnamed++;
}
if (GV->isConstant() || !GV->hasInitializer())
return false;
return ProcessInternalGlobal(GV, GVI, GS);
}
bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
Module::global_iterator &GVI,
const GlobalStatus &GS) {
auto &DL = GV->getParent()->getDataLayout();
if (!GS.HasMultipleAccessingFunctions &&
GS.AccessingFunction && !GS.HasNonInstructionUser &&
GV->getType()->getElementType()->isSingleValueType() &&
GS.AccessingFunction->getName() == "main" &&
GS.AccessingFunction->hasExternalLinkage() &&
GV->getType()->getAddressSpace() == 0) {
DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV);
Instruction &FirstI = const_cast<Instruction&>(*GS.AccessingFunction
->getEntryBlock().begin());
Type *ElemTy = GV->getType()->getElementType();
AllocaInst *Alloca = new AllocaInst(ElemTy, nullptr,
GV->getName(), &FirstI);
if (!isa<UndefValue>(GV->getInitializer()))
new StoreInst(GV->getInitializer(), Alloca, &FirstI);
GV->replaceAllUsesWith(Alloca);
GV->eraseFromParent();
++NumLocalized;
return true;
}
if (!GS.IsLoaded) {
DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV);
bool Changed;
if (isLeakCheckerRoot(GV)) {
Changed = CleanupPointerRootUsers(GV, TLI);
} else {
Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI);
}
if (GV->use_empty()) {
GV->eraseFromParent();
++NumDeleted;
Changed = true;
}
return Changed;
} else if (GS.StoredType <= GlobalStatus::InitializerStored) {
DEBUG(dbgs() << "MARKING CONSTANT: " << *GV << "\n");
GV->setConstant(true);
CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI);
if (GV->use_empty()) {
DEBUG(dbgs() << " *** Marking constant allowed us to simplify "
<< "all users and delete global!\n");
GV->eraseFromParent();
++NumDeleted;
}
++NumMarked;
return true;
} else if (!GV->getInitializer()->getType()->isSingleValueType()) {
const DataLayout &DL = GV->getParent()->getDataLayout();
if (GlobalVariable *FirstNewGV = SRAGlobal(GV, DL)) {
GVI = FirstNewGV; return true;
}
} else if (GS.StoredType == GlobalStatus::StoredOnce) {
if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
if (isa<UndefValue>(GV->getInitializer())) {
GV->setInitializer(SOVConstant);
CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI);
if (GV->use_empty()) {
DEBUG(dbgs() << " *** Substituting initializer allowed us to "
<< "simplify all users and delete global!\n");
GV->eraseFromParent();
++NumDeleted;
} else {
GVI = GV;
}
++NumSubstitute;
return true;
}
if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GS.Ordering, GVI,
DL, TLI))
return true;
if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) {
if (GS.Ordering == NotAtomic) {
if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) {
++NumShrunkToBool;
return true;
}
}
}
}
return false;
}
static void ChangeCalleesToFastCall(Function *F) {
for (User *U : F->users()) {
if (isa<BlockAddress>(U))
continue;
CallSite CS(cast<Instruction>(U));
CS.setCallingConv(CallingConv::Fast);
}
}
static AttributeSet StripNest(LLVMContext &C, const AttributeSet &Attrs) {
for (unsigned i = 0, e = Attrs.getNumSlots(); i != e; ++i) {
unsigned Index = Attrs.getSlotIndex(i);
if (!Attrs.getSlotAttributes(i).hasAttribute(Index, Attribute::Nest))
continue;
return Attrs.removeAttribute(C, Index, Attribute::Nest);
}
return Attrs;
}
static void RemoveNestAttribute(Function *F) {
F->setAttributes(StripNest(F->getContext(), F->getAttributes()));
for (User *U : F->users()) {
if (isa<BlockAddress>(U))
continue;
CallSite CS(cast<Instruction>(U));
CS.setAttributes(StripNest(F->getContext(), CS.getAttributes()));
}
}
static bool isProfitableToMakeFastCC(Function *F) {
CallingConv::ID CC = F->getCallingConv();
return CC == CallingConv::C || CC == CallingConv::X86_ThisCall;
}
bool GlobalOpt::OptimizeFunctions(Module &M) {
bool Changed = false;
for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
Function *F = FI++;
if (!F->hasName() && !F->isDeclaration() && !F->hasLocalLinkage())
F->setLinkage(GlobalValue::InternalLinkage);
const Comdat *C = F->getComdat();
bool inComdat = C && NotDiscardableComdats.count(C);
F->removeDeadConstantUsers();
if ((!inComdat || F->hasLocalLinkage()) && F->isDefTriviallyDead()) {
F->eraseFromParent();
Changed = true;
++NumFnDeleted;
} else if (F->hasLocalLinkage()) {
if (isProfitableToMakeFastCC(F) && !F->isVarArg() &&
!F->hasAddressTaken()) {
F->setCallingConv(CallingConv::Fast);
ChangeCalleesToFastCall(F);
++NumFastCallFns;
Changed = true;
}
if (F->getAttributes().hasAttrSomewhere(Attribute::Nest) &&
!F->hasAddressTaken()) {
RemoveNestAttribute(F);
++NumNestRemoved;
Changed = true;
}
}
}
return Changed;
}
bool GlobalOpt::OptimizeGlobalVars(Module &M) {
bool Changed = false;
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
if (!GV->hasName() && !GV->isDeclaration() && !GV->hasLocalLinkage())
GV->setLinkage(GlobalValue::InternalLinkage);
if (GV->hasInitializer())
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) {
auto &DL = M.getDataLayout();
Constant *New = ConstantFoldConstantExpression(CE, DL, TLI);
if (New && New != CE)
GV->setInitializer(New);
}
if (GV->isDiscardableIfUnused()) {
if (const Comdat *C = GV->getComdat())
if (NotDiscardableComdats.count(C) && !GV->hasLocalLinkage())
continue;
Changed |= ProcessGlobal(GV, GVI);
}
}
return Changed;
}
static inline bool
isSimpleEnoughValueToCommit(Constant *C,
SmallPtrSetImpl<Constant *> &SimpleConstants,
const DataLayout &DL);
static bool
isSimpleEnoughValueToCommitHelper(Constant *C,
SmallPtrSetImpl<Constant *> &SimpleConstants,
const DataLayout &DL) {
if (auto *GV = dyn_cast<GlobalValue>(C))
return !GV->hasDLLImportStorageClass() && !GV->isThreadLocal();
if (C->getNumOperands() == 0 || isa<BlockAddress>(C))
return true;
if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
isa<ConstantVector>(C)) {
for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
Constant *Op = cast<Constant>(C->getOperand(i));
if (!isSimpleEnoughValueToCommit(Op, SimpleConstants, DL))
return false;
}
return true;
}
ConstantExpr *CE = cast<ConstantExpr>(C);
switch (CE->getOpcode()) {
case Instruction::BitCast:
return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL);
case Instruction::IntToPtr:
case Instruction::PtrToInt:
if (DL.getTypeSizeInBits(CE->getType()) !=
DL.getTypeSizeInBits(CE->getOperand(0)->getType()))
return false;
return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL);
case Instruction::GetElementPtr:
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
if (!isa<ConstantInt>(CE->getOperand(i)))
return false;
return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL);
case Instruction::Add:
if (!isa<ConstantInt>(CE->getOperand(1)))
return false;
return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL);
}
return false;
}
static inline bool
isSimpleEnoughValueToCommit(Constant *C,
SmallPtrSetImpl<Constant *> &SimpleConstants,
const DataLayout &DL) {
if (!SimpleConstants.insert(C).second)
return true;
return isSimpleEnoughValueToCommitHelper(C, SimpleConstants, DL);
}
static bool isSimpleEnoughPointerToCommit(Constant *C) {
if (!cast<PointerType>(C->getType())->getElementType()->isSingleValueType())
return false;
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
return GV->hasUniqueInitializer();
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::GetElementPtr &&
isa<GlobalVariable>(CE->getOperand(0)) &&
cast<GEPOperator>(CE)->isInBounds()) {
GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
if (!GV->hasUniqueInitializer())
return false;
ConstantInt *CI = dyn_cast<ConstantInt>(*std::next(CE->op_begin()));
if (!CI || !CI->isZero()) return false;
if (!CE->isGEPWithNoNotionalOverIndexing())
return false;
return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
} else if (CE->getOpcode() == Instruction::BitCast &&
isa<GlobalVariable>(CE->getOperand(0))) {
return cast<GlobalVariable>(CE->getOperand(0))->hasUniqueInitializer();
}
}
return false;
}
static Constant *EvaluateStoreInto(Constant *Init, Constant *Val,
ConstantExpr *Addr, unsigned OpNo) {
if (OpNo == Addr->getNumOperands()) {
assert(Val->getType() == Init->getType() && "Type mismatch!");
return Val;
}
SmallVector<Constant*, 32> Elts;
if (StructType *STy = dyn_cast<StructType>(Init->getType())) {
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
Elts.push_back(Init->getAggregateElement(i));
ConstantInt *CU = cast<ConstantInt>(Addr->getOperand(OpNo));
unsigned Idx = CU->getZExtValue();
assert(Idx < STy->getNumElements() && "Struct index out of range!");
Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1);
return ConstantStruct::get(STy, Elts);
}
ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo));
SequentialType *InitTy = cast<SequentialType>(Init->getType());
uint64_t NumElts;
if (ArrayType *ATy = dyn_cast<ArrayType>(InitTy))
NumElts = ATy->getNumElements();
else
NumElts = InitTy->getVectorNumElements();
for (uint64_t i = 0, e = NumElts; i != e; ++i)
Elts.push_back(Init->getAggregateElement(i));
assert(CI->getZExtValue() < NumElts);
Elts[CI->getZExtValue()] =
EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1);
if (Init->getType()->isArrayTy())
return ConstantArray::get(cast<ArrayType>(InitTy), Elts);
return ConstantVector::get(Elts);
}
static void CommitValueTo(Constant *Val, Constant *Addr) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
assert(GV->hasInitializer());
GV->setInitializer(Val);
return;
}
ConstantExpr *CE = cast<ConstantExpr>(Addr);
GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
GV->setInitializer(EvaluateStoreInto(GV->getInitializer(), Val, CE, 2));
}
namespace {
class Evaluator {
public:
Evaluator(const DataLayout &DL, const TargetLibraryInfo *TLI)
: DL(DL), TLI(TLI) {
ValueStack.emplace_back();
}
~Evaluator() {
for (auto &Tmp : AllocaTmps)
if (!Tmp->use_empty())
Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType()));
}
bool EvaluateFunction(Function *F, Constant *&RetVal,
const SmallVectorImpl<Constant*> &ActualArgs);
bool EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB);
Constant *getVal(Value *V) {
if (Constant *CV = dyn_cast<Constant>(V)) return CV;
Constant *R = ValueStack.back().lookup(V);
assert(R && "Reference to an uncomputed value!");
return R;
}
void setVal(Value *V, Constant *C) {
ValueStack.back()[V] = C;
}
const DenseMap<Constant*, Constant*> &getMutatedMemory() const {
return MutatedMemory;
}
const SmallPtrSetImpl<GlobalVariable*> &getInvariants() const {
return Invariants;
}
private:
Constant *ComputeLoadResult(Constant *P);
std::deque<DenseMap<Value*, Constant*>> ValueStack;
SmallVector<Function*, 4> CallStack;
DenseMap<Constant*, Constant*> MutatedMemory;
SmallVector<std::unique_ptr<GlobalVariable>, 32> AllocaTmps;
SmallPtrSet<GlobalVariable*, 8> Invariants;
SmallPtrSet<Constant*, 8> SimpleConstants;
const DataLayout &DL;
const TargetLibraryInfo *TLI;
};
}
Constant *Evaluator::ComputeLoadResult(Constant *P) {
DenseMap<Constant*, Constant*>::const_iterator I = MutatedMemory.find(P);
if (I != MutatedMemory.end()) return I->second;
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) {
if (GV->hasDefinitiveInitializer())
return GV->getInitializer();
return nullptr;
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P))
if (CE->getOpcode() == Instruction::GetElementPtr &&
isa<GlobalVariable>(CE->getOperand(0))) {
GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
if (GV->hasDefinitiveInitializer())
return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
}
return nullptr; }
bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
BasicBlock *&NextBB) {
while (1) {
Constant *InstResult = nullptr;
DEBUG(dbgs() << "Evaluating Instruction: " << *CurInst << "\n");
if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
if (!SI->isSimple()) {
DEBUG(dbgs() << "Store is not simple! Can not evaluate.\n");
return false; }
Constant *Ptr = getVal(SI->getOperand(1));
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
DEBUG(dbgs() << "Folding constant ptr expression: " << *Ptr);
Ptr = ConstantFoldConstantExpression(CE, DL, TLI);
DEBUG(dbgs() << "; To: " << *Ptr << "\n");
}
if (!isSimpleEnoughPointerToCommit(Ptr)) {
DEBUG(dbgs() << "Pointer is too complex for us to evaluate store.");
return false;
}
Constant *Val = getVal(SI->getOperand(0));
if (!isSimpleEnoughValueToCommit(Val, SimpleConstants, DL)) {
DEBUG(dbgs() << "Store value is too complex to evaluate store. " << *Val
<< "\n");
return false;
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
if (CE->getOpcode() == Instruction::BitCast) {
DEBUG(dbgs() << "Attempting to resolve bitcast on constant ptr.\n");
Ptr = CE->getOperand(0);
Type *NewTy = cast<PointerType>(Ptr->getType())->getElementType();
while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) {
if (StructType *STy = dyn_cast<StructType>(NewTy)) {
NewTy = STy->getTypeAtIndex(0U);
IntegerType *IdxTy = IntegerType::get(NewTy->getContext(), 32);
Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
Ptr = ConstantFoldConstantExpression(CE, DL, TLI);
} else {
DEBUG(dbgs() << "Failed to bitcast constant ptr, can not "
"evaluate.\n");
return false;
}
}
Val = ConstantExpr::getBitCast(Val, NewTy);
DEBUG(dbgs() << "Evaluated bitcast: " << *Val << "\n");
}
}
MutatedMemory[Ptr] = Val;
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) {
InstResult = ConstantExpr::get(BO->getOpcode(),
getVal(BO->getOperand(0)),
getVal(BO->getOperand(1)));
DEBUG(dbgs() << "Found a BinaryOperator! Simplifying: " << *InstResult
<< "\n");
} else if (CmpInst *CI = dyn_cast<CmpInst>(CurInst)) {
InstResult = ConstantExpr::getCompare(CI->getPredicate(),
getVal(CI->getOperand(0)),
getVal(CI->getOperand(1)));
DEBUG(dbgs() << "Found a CmpInst! Simplifying: " << *InstResult
<< "\n");
} else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) {
InstResult = ConstantExpr::getCast(CI->getOpcode(),
getVal(CI->getOperand(0)),
CI->getType());
DEBUG(dbgs() << "Found a Cast! Simplifying: " << *InstResult
<< "\n");
} else if (SelectInst *SI = dyn_cast<SelectInst>(CurInst)) {
InstResult = ConstantExpr::getSelect(getVal(SI->getOperand(0)),
getVal(SI->getOperand(1)),
getVal(SI->getOperand(2)));
DEBUG(dbgs() << "Found a Select! Simplifying: " << *InstResult
<< "\n");
} else if (auto *EVI = dyn_cast<ExtractValueInst>(CurInst)) {
InstResult = ConstantExpr::getExtractValue(
getVal(EVI->getAggregateOperand()), EVI->getIndices());
DEBUG(dbgs() << "Found an ExtractValueInst! Simplifying: " << *InstResult
<< "\n");
} else if (auto *IVI = dyn_cast<InsertValueInst>(CurInst)) {
InstResult = ConstantExpr::getInsertValue(
getVal(IVI->getAggregateOperand()),
getVal(IVI->getInsertedValueOperand()), IVI->getIndices());
DEBUG(dbgs() << "Found an InsertValueInst! Simplifying: " << *InstResult
<< "\n");
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
Constant *P = getVal(GEP->getOperand(0));
SmallVector<Constant*, 8> GEPOps;
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end();
i != e; ++i)
GEPOps.push_back(getVal(*i));
InstResult =
ConstantExpr::getGetElementPtr(P, GEPOps,
cast<GEPOperator>(GEP)->isInBounds());
DEBUG(dbgs() << "Found a GEP! Simplifying: " << *InstResult
<< "\n");
} else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
if (!LI->isSimple()) {
DEBUG(dbgs() << "Found a Load! Not a simple load, can not evaluate.\n");
return false; }
Constant *Ptr = getVal(LI->getOperand(0));
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
Ptr = ConstantFoldConstantExpression(CE, DL, TLI);
DEBUG(dbgs() << "Found a constant pointer expression, constant "
"folding: " << *Ptr << "\n");
}
InstResult = ComputeLoadResult(Ptr);
if (!InstResult) {
DEBUG(dbgs() << "Failed to compute load result. Can not evaluate load."
"\n");
return false; }
DEBUG(dbgs() << "Evaluated load: " << *InstResult << "\n");
} else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
if (AI->isArrayAllocation()) {
DEBUG(dbgs() << "Found an array alloca. Can not evaluate.\n");
return false; }
Type *Ty = AI->getType()->getElementType();
AllocaTmps.push_back(
make_unique<GlobalVariable>(Ty, false, GlobalValue::InternalLinkage,
UndefValue::get(Ty), AI->getName()));
InstResult = AllocaTmps.back().get();
DEBUG(dbgs() << "Found an alloca. Result: " << *InstResult << "\n");
} else if (isa<CallInst>(CurInst) || isa<InvokeInst>(CurInst)) {
CallSite CS(CurInst);
if (isa<DbgInfoIntrinsic>(CS.getInstruction())) {
DEBUG(dbgs() << "Ignoring debug info.\n");
++CurInst;
continue;
}
if (isa<InlineAsm>(CS.getCalledValue())) {
DEBUG(dbgs() << "Found inline asm, can not evaluate.\n");
return false;
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
if (MemSetInst *MSI = dyn_cast<MemSetInst>(II)) {
if (MSI->isVolatile()) {
DEBUG(dbgs() << "Can not optimize a volatile memset " <<
"intrinsic.\n");
return false;
}
Constant *Ptr = getVal(MSI->getDest());
Constant *Val = getVal(MSI->getValue());
Constant *DestVal = ComputeLoadResult(getVal(Ptr));
if (Val->isNullValue() && DestVal && DestVal->isNullValue()) {
DEBUG(dbgs() << "Ignoring no-op memset.\n");
++CurInst;
continue;
}
}
if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
II->getIntrinsicID() == Intrinsic::lifetime_end) {
DEBUG(dbgs() << "Ignoring lifetime intrinsic.\n");
++CurInst;
continue;
}
if (II->getIntrinsicID() == Intrinsic::invariant_start) {
if (!II->use_empty()) {
DEBUG(dbgs() << "Found unused invariant_start. Can't evaluate.\n");
return false;
}
ConstantInt *Size = cast<ConstantInt>(II->getArgOperand(0));
Value *PtrArg = getVal(II->getArgOperand(1));
Value *Ptr = PtrArg->stripPointerCasts();
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) {
Type *ElemTy = cast<PointerType>(GV->getType())->getElementType();
if (!Size->isAllOnesValue() &&
Size->getValue().getLimitedValue() >=
DL.getTypeStoreSize(ElemTy)) {
Invariants.insert(GV);
DEBUG(dbgs() << "Found a global var that is an invariant: " << *GV
<< "\n");
} else {
DEBUG(dbgs() << "Found a global var, but can not treat it as an "
"invariant.\n");
}
}
++CurInst;
continue;
}
DEBUG(dbgs() << "Unknown intrinsic. Can not evaluate.\n");
return false;
}
Function *Callee = dyn_cast<Function>(getVal(CS.getCalledValue()));
if (!Callee || Callee->mayBeOverridden()) {
DEBUG(dbgs() << "Can not resolve function pointer.\n");
return false; }
SmallVector<Constant*, 8> Formals;
for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end(); i != e; ++i)
Formals.push_back(getVal(*i));
if (Callee->isDeclaration()) {
if (Constant *C = ConstantFoldCall(Callee, Formals, TLI)) {
InstResult = C;
DEBUG(dbgs() << "Constant folded function call. Result: " <<
*InstResult << "\n");
} else {
DEBUG(dbgs() << "Can not constant fold function call.\n");
return false;
}
} else {
if (Callee->getFunctionType()->isVarArg()) {
DEBUG(dbgs() << "Can not constant fold vararg function call.\n");
return false;
}
Constant *RetVal = nullptr;
ValueStack.emplace_back();
if (!EvaluateFunction(Callee, RetVal, Formals)) {
DEBUG(dbgs() << "Failed to evaluate function.\n");
return false;
}
ValueStack.pop_back();
InstResult = RetVal;
if (InstResult) {
DEBUG(dbgs() << "Successfully evaluated function. Result: " <<
InstResult << "\n\n");
} else {
DEBUG(dbgs() << "Successfully evaluated function. Result: 0\n\n");
}
}
} else if (isa<TerminatorInst>(CurInst)) {
DEBUG(dbgs() << "Found a terminator instruction.\n");
if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
if (BI->isUnconditional()) {
NextBB = BI->getSuccessor(0);
} else {
ConstantInt *Cond =
dyn_cast<ConstantInt>(getVal(BI->getCondition()));
if (!Cond) return false;
NextBB = BI->getSuccessor(!Cond->getZExtValue());
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
ConstantInt *Val =
dyn_cast<ConstantInt>(getVal(SI->getCondition()));
if (!Val) return false; NextBB = SI->findCaseValue(Val).getCaseSuccessor();
} else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) {
Value *Val = getVal(IBI->getAddress())->stripPointerCasts();
if (BlockAddress *BA = dyn_cast<BlockAddress>(Val))
NextBB = BA->getBasicBlock();
else
return false; } else if (isa<ReturnInst>(CurInst)) {
NextBB = nullptr;
} else {
DEBUG(dbgs() << "Can not handle terminator.");
return false; }
DEBUG(dbgs() << "Successfully evaluated block.\n");
return true;
} else {
DEBUG(dbgs() << "Failed to evaluate block due to unhandled instruction."
"\n");
return false;
}
if (!CurInst->use_empty()) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(InstResult))
InstResult = ConstantFoldConstantExpression(CE, DL, TLI);
setVal(CurInst, InstResult);
}
if (InvokeInst *II = dyn_cast<InvokeInst>(CurInst)) {
NextBB = II->getNormalDest();
DEBUG(dbgs() << "Found an invoke instruction. Finished Block.\n\n");
return true;
}
++CurInst;
}
}
bool Evaluator::EvaluateFunction(Function *F, Constant *&RetVal,
const SmallVectorImpl<Constant*> &ActualArgs) {
if (std::find(CallStack.begin(), CallStack.end(), F) != CallStack.end())
return false;
CallStack.push_back(F);
unsigned ArgNo = 0;
for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E;
++AI, ++ArgNo)
setVal(AI, ActualArgs[ArgNo]);
SmallPtrSet<BasicBlock*, 32> ExecutedBlocks;
BasicBlock *CurBB = F->begin();
BasicBlock::iterator CurInst = CurBB->begin();
while (1) {
BasicBlock *NextBB = nullptr; DEBUG(dbgs() << "Trying to evaluate BB: " << *CurBB << "\n");
if (!EvaluateBlock(CurInst, NextBB))
return false;
if (!NextBB) {
ReturnInst *RI = cast<ReturnInst>(CurBB->getTerminator());
if (RI->getNumOperands())
RetVal = getVal(RI->getOperand(0));
CallStack.pop_back();
return true;
}
if (!ExecutedBlocks.insert(NextBB).second)
return false;
PHINode *PN = nullptr;
for (CurInst = NextBB->begin();
(PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
setVal(PN, getVal(PN->getIncomingValueForBlock(CurBB)));
CurBB = NextBB;
}
}
static bool EvaluateStaticConstructor(Function *F, const DataLayout &DL,
const TargetLibraryInfo *TLI) {
Evaluator Eval(DL, TLI);
Constant *RetValDummy;
bool EvalSuccess = Eval.EvaluateFunction(F, RetValDummy,
SmallVector<Constant*, 0>());
if (EvalSuccess) {
++NumCtorsEvaluated;
DEBUG(dbgs() << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
<< F->getName() << "' to " << Eval.getMutatedMemory().size()
<< " stores.\n");
for (DenseMap<Constant*, Constant*>::const_iterator I =
Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end();
I != E; ++I)
CommitValueTo(I->second, I->first);
for (GlobalVariable *GV : Eval.getInvariants())
GV->setConstant(true);
}
return EvalSuccess;
}
static int compareNames(Constant *const *A, Constant *const *B) {
return (*A)->getName().compare((*B)->getName());
}
static void setUsedInitializer(GlobalVariable &V,
const SmallPtrSet<GlobalValue *, 8> &Init) {
if (Init.empty()) {
V.eraseFromParent();
return;
}
PointerType *Int8PtrTy = Type::getInt8PtrTy(V.getContext(), 0);
SmallVector<llvm::Constant *, 8> UsedArray;
for (GlobalValue *GV : Init) {
Constant *Cast
= ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, Int8PtrTy);
UsedArray.push_back(Cast);
}
array_pod_sort(UsedArray.begin(), UsedArray.end(), compareNames);
ArrayType *ATy = ArrayType::get(Int8PtrTy, UsedArray.size());
Module *M = V.getParent();
V.removeFromParent();
GlobalVariable *NV =
new GlobalVariable(*M, ATy, false, llvm::GlobalValue::AppendingLinkage,
llvm::ConstantArray::get(ATy, UsedArray), "");
NV->takeName(&V);
NV->setSection("llvm.metadata");
delete &V;
}
namespace {
class LLVMUsed {
SmallPtrSet<GlobalValue *, 8> Used;
SmallPtrSet<GlobalValue *, 8> CompilerUsed;
GlobalVariable *UsedV;
GlobalVariable *CompilerUsedV;
public:
LLVMUsed(Module &M) {
UsedV = collectUsedGlobalVariables(M, Used, false);
CompilerUsedV = collectUsedGlobalVariables(M, CompilerUsed, true);
}
typedef SmallPtrSet<GlobalValue *, 8>::iterator iterator;
typedef iterator_range<iterator> used_iterator_range;
iterator usedBegin() { return Used.begin(); }
iterator usedEnd() { return Used.end(); }
used_iterator_range used() {
return used_iterator_range(usedBegin(), usedEnd());
}
iterator compilerUsedBegin() { return CompilerUsed.begin(); }
iterator compilerUsedEnd() { return CompilerUsed.end(); }
used_iterator_range compilerUsed() {
return used_iterator_range(compilerUsedBegin(), compilerUsedEnd());
}
bool usedCount(GlobalValue *GV) const { return Used.count(GV); }
bool compilerUsedCount(GlobalValue *GV) const {
return CompilerUsed.count(GV);
}
bool usedErase(GlobalValue *GV) { return Used.erase(GV); }
bool compilerUsedErase(GlobalValue *GV) { return CompilerUsed.erase(GV); }
bool usedInsert(GlobalValue *GV) { return Used.insert(GV).second; }
bool compilerUsedInsert(GlobalValue *GV) {
return CompilerUsed.insert(GV).second;
}
void syncVariablesAndSets() {
if (UsedV)
setUsedInitializer(*UsedV, Used);
if (CompilerUsedV)
setUsedInitializer(*CompilerUsedV, CompilerUsed);
}
};
}
static bool hasUseOtherThanLLVMUsed(GlobalAlias &GA, const LLVMUsed &U) {
if (GA.use_empty()) return false;
assert((!U.usedCount(&GA) || !U.compilerUsedCount(&GA)) &&
"We should have removed the duplicated "
"element from llvm.compiler.used");
if (!GA.hasOneUse())
return true;
return !U.usedCount(&GA) && !U.compilerUsedCount(&GA);
}
static bool hasMoreThanOneUseOtherThanLLVMUsed(GlobalValue &V,
const LLVMUsed &U) {
unsigned N = 2;
assert((!U.usedCount(&V) || !U.compilerUsedCount(&V)) &&
"We should have removed the duplicated "
"element from llvm.compiler.used");
if (U.usedCount(&V) || U.compilerUsedCount(&V))
++N;
return V.hasNUsesOrMore(N);
}
static bool mayHaveOtherReferences(GlobalAlias &GA, const LLVMUsed &U) {
if (!GA.hasLocalLinkage())
return true;
return U.usedCount(&GA) || U.compilerUsedCount(&GA);
}
static bool hasUsesToReplace(GlobalAlias &GA, const LLVMUsed &U,
bool &RenameTarget) {
RenameTarget = false;
bool Ret = false;
if (hasUseOtherThanLLVMUsed(GA, U))
Ret = true;
if (!mayHaveOtherReferences(GA, U))
return Ret;
Constant *Aliasee = GA.getAliasee();
GlobalValue *Target = cast<GlobalValue>(Aliasee->stripPointerCasts());
if (!Target->hasLocalLinkage())
return Ret;
if (hasMoreThanOneUseOtherThanLLVMUsed(*Target, U))
return Ret;
RenameTarget = true;
return true;
}
bool GlobalOpt::OptimizeGlobalAliases(Module &M) {
bool Changed = false;
LLVMUsed Used(M);
for (GlobalValue *GV : Used.used())
Used.compilerUsedErase(GV);
for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
I != E;) {
Module::alias_iterator J = I++;
if (!J->hasName() && !J->isDeclaration() && !J->hasLocalLinkage())
J->setLinkage(GlobalValue::InternalLinkage);
if (J->mayBeOverridden())
continue;
Constant *Aliasee = J->getAliasee();
GlobalValue *Target = dyn_cast<GlobalValue>(Aliasee->stripPointerCasts());
if (!Target)
continue;
Target->removeDeadConstantUsers();
bool RenameTarget;
if (!hasUsesToReplace(*J, Used, RenameTarget))
continue;
J->replaceAllUsesWith(ConstantExpr::getBitCast(Aliasee, J->getType()));
++NumAliasesResolved;
Changed = true;
if (RenameTarget) {
Target->takeName(J);
Target->setLinkage(J->getLinkage());
Target->setVisibility(J->getVisibility());
Target->setDLLStorageClass(J->getDLLStorageClass());
if (Used.usedErase(J))
Used.usedInsert(Target);
if (Used.compilerUsedErase(J))
Used.compilerUsedInsert(Target);
} else if (mayHaveOtherReferences(*J, Used))
continue;
M.getAliasList().erase(J);
++NumAliasesRemoved;
Changed = true;
}
Used.syncVariablesAndSets();
return Changed;
}
static Function *FindCXAAtExit(Module &M, TargetLibraryInfo *TLI) {
if (!TLI->has(LibFunc::cxa_atexit))
return nullptr;
Function *Fn = M.getFunction(TLI->getName(LibFunc::cxa_atexit));
if (!Fn)
return nullptr;
FunctionType *FTy = Fn->getFunctionType();
if (!FTy->getReturnType()->isIntegerTy() ||
FTy->getNumParams() != 3 ||
!FTy->getParamType(0)->isPointerTy() ||
!FTy->getParamType(1)->isPointerTy() ||
!FTy->getParamType(2)->isPointerTy())
return nullptr;
return Fn;
}
static bool cxxDtorIsEmpty(const Function &Fn,
SmallPtrSet<const Function *, 8> &CalledFunctions) {
if (Fn.isDeclaration())
return false;
if (++Fn.begin() != Fn.end())
return false;
const BasicBlock &EntryBlock = Fn.getEntryBlock();
for (BasicBlock::const_iterator I = EntryBlock.begin(), E = EntryBlock.end();
I != E; ++I) {
if (const CallInst *CI = dyn_cast<CallInst>(I)) {
if (isa<DbgInfoIntrinsic>(CI))
continue;
const Function *CalledFn = CI->getCalledFunction();
if (!CalledFn)
return false;
SmallPtrSet<const Function *, 8> NewCalledFunctions(CalledFunctions);
if (!NewCalledFunctions.insert(CalledFn).second)
return false;
if (!cxxDtorIsEmpty(*CalledFn, NewCalledFunctions))
return false;
} else if (isa<ReturnInst>(*I))
return true; else if (I->mayHaveSideEffects())
return false; }
return false;
}
bool GlobalOpt::OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn) {
bool Changed = false;
for (auto I = CXAAtExitFn->user_begin(), E = CXAAtExitFn->user_end();
I != E;) {
CallInst *CI = dyn_cast<CallInst>(*I++);
if (!CI)
continue;
Function *DtorFn =
dyn_cast<Function>(CI->getArgOperand(0)->stripPointerCasts());
if (!DtorFn)
continue;
SmallPtrSet<const Function *, 8> CalledFunctions;
if (!cxxDtorIsEmpty(*DtorFn, CalledFunctions))
continue;
CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
CI->eraseFromParent();
++NumCXXDtorsRemoved;
Changed |= true;
}
return Changed;
}
bool GlobalOpt::runOnModule(Module &M) {
bool Changed = false;
auto &DL = M.getDataLayout();
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
bool LocalChange = true;
while (LocalChange) {
LocalChange = false;
NotDiscardableComdats.clear();
for (const GlobalVariable &GV : M.globals())
if (const Comdat *C = GV.getComdat())
if (!GV.isDiscardableIfUnused() || !GV.use_empty())
NotDiscardableComdats.insert(C);
for (Function &F : M)
if (const Comdat *C = F.getComdat())
if (!F.isDefTriviallyDead())
NotDiscardableComdats.insert(C);
for (GlobalAlias &GA : M.aliases())
if (const Comdat *C = GA.getComdat())
if (!GA.isDiscardableIfUnused() || !GA.use_empty())
NotDiscardableComdats.insert(C);
LocalChange |= OptimizeFunctions(M);
LocalChange |= optimizeGlobalCtorsList(M, [&](Function *F) {
return EvaluateStaticConstructor(F, DL, TLI);
});
LocalChange |= OptimizeGlobalVars(M);
LocalChange |= OptimizeGlobalAliases(M);
Function *CXAAtExitFn = FindCXAAtExit(M, TLI);
if (CXAAtExitFn)
LocalChange |= OptimizeEmptyGlobalCXXDtors(CXAAtExitFn);
Changed |= LocalChange;
}
return Changed;
}