#include "llvm/Pass.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/STLExtras.h"
#include <algorithm>
-#include <set>
using namespace llvm;
STATISTIC(NumMarked , "Number of globals marked constant");
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");
namespace {
struct VISIBILITY_HIDDEN GlobalOpt : public ModulePass {
AU.addRequired<TargetData>();
}
static char ID; // Pass identification, replacement for typeid
- GlobalOpt() : ModulePass((intptr_t)&ID) {}
+ GlobalOpt() : ModulePass(&ID) {}
bool runOnModule(Module &M);
GlobalVariable *FindGlobalCtors(Module &M);
bool OptimizeFunctions(Module &M);
bool OptimizeGlobalVars(Module &M);
+ bool ResolveAliases(Module &M);
bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
};
-
- char GlobalOpt::ID = 0;
- RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
}
+char GlobalOpt::ID = 0;
+static RegisterPass<GlobalOpt> X("globalopt", "Global Variable Optimizer");
+
ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); }
+namespace {
+
/// GlobalStatus - As we analyze each global, keep track of some information
/// about it. If we find out that the address of the global is taken, none of
/// this info will be accurate.
/// HasPHIUser - Set to true if this global has a user that is a PHI node.
bool HasPHIUser;
- /// isNotSuitableForSRA - Keep track of whether any SRA preventing users of
- /// the global exist. Such users include GEP instruction with variable
- /// indexes, and non-gep/load/store users like constant expr casts.
- bool isNotSuitableForSRA;
-
GlobalStatus() : isLoaded(false), StoredType(NotStored), StoredOnceValue(0),
AccessingFunction(0), HasMultipleAccessingFunctions(false),
- HasNonInstructionUser(false), HasPHIUser(false),
- isNotSuitableForSRA(false) {}
+ HasNonInstructionUser(false), HasPHIUser(false) {}
};
-
+}
/// ConstantIsDead - Return true if the specified constant is (transitively)
-/// dead. The constant may be used by other constants (e.g. constant arrays and
-/// constant exprs) as long as they are dead, but it cannot be used by anything
-/// else.
-static bool ConstantIsDead(Constant *C) {
+/// dead. The constant may be used by other constants (e.g. constant arrays,
+/// constant exprs, constant global variables) as long as they are dead,
+/// but it cannot be used by anything else. If DeadGVs is not null then
+/// record dead constant GV users.
+static bool ConstantIsDead(Constant *C,
+ SmallPtrSet<GlobalVariable *, 4> *DeadGVs = false) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
+ if (GV->hasLocalLinkage() && GV->use_empty()) {
+ if (DeadGVs)
+ DeadGVs->insert(GV);
+ return true;
+ }
if (isa<GlobalValue>(C)) return false;
for (Value::use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
if (Constant *CU = dyn_cast<Constant>(*UI)) {
- if (!ConstantIsDead(CU)) return false;
+ if (!ConstantIsDead(CU, DeadGVs)) return false;
} else
return false;
return true;
/// can't do anything with it.
///
static bool AnalyzeGlobal(Value *V, GlobalStatus &GS,
- std::set<PHINode*> &PHIUsers) {
+ SmallPtrSet<PHINode*, 16> &PHIUsers) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
GS.HasNonInstructionUser = true;
if (AnalyzeGlobal(CE, GS, PHIUsers)) return true;
- if (CE->getOpcode() != Instruction::GetElementPtr)
- GS.isNotSuitableForSRA = true;
- else if (!GS.isNotSuitableForSRA) {
- // Check to see if this ConstantExpr GEP is SRA'able. In particular, we
- // don't like < 3 operand CE's, and we don't like non-constant integer
- // indices.
- if (CE->getNumOperands() < 3 || !CE->getOperand(1)->isNullValue())
- GS.isNotSuitableForSRA = true;
- else {
- for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
- if (!isa<ConstantInt>(CE->getOperand(i))) {
- GS.isNotSuitableForSRA = true;
- break;
- }
- }
- }
} else if (Instruction *I = dyn_cast<Instruction>(*UI)) {
if (!GS.HasMultipleAccessingFunctions) {
else if (GS.AccessingFunction != F)
GS.HasMultipleAccessingFunctions = true;
}
- if (isa<LoadInst>(I)) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
GS.isLoaded = true;
+ if (LI->isVolatile()) return true; // Don't hack on volatile loads.
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
// Don't allow a store OF the address, only stores TO the address.
if (SI->getOperand(0) == V) return true;
+ if (SI->isVolatile()) return true; // Don't hack on volatile stores.
+
// If this is a direct store to the global (i.e., the global is a scalar
// value, not an aggregate), keep more specific information about
// stores.
- if (GS.StoredType != GlobalStatus::isStored)
+ if (GS.StoredType != GlobalStatus::isStored) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(SI->getOperand(1))){
Value *StoredVal = SI->getOperand(0);
if (StoredVal == GV->getInitializer()) {
} else {
GS.StoredType = GlobalStatus::isStored;
}
+ }
} else if (isa<GetElementPtrInst>(I)) {
if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
-
- // If the first two indices are constants, this can be SRA'd.
- if (isa<GlobalVariable>(I->getOperand(0))) {
- if (I->getNumOperands() < 3 || !isa<Constant>(I->getOperand(1)) ||
- !cast<Constant>(I->getOperand(1))->isNullValue() ||
- !isa<ConstantInt>(I->getOperand(2)))
- GS.isNotSuitableForSRA = true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I->getOperand(0))){
- if (CE->getOpcode() != Instruction::GetElementPtr ||
- CE->getNumOperands() < 3 || I->getNumOperands() < 2 ||
- !isa<Constant>(I->getOperand(0)) ||
- !cast<Constant>(I->getOperand(0))->isNullValue())
- GS.isNotSuitableForSRA = true;
- } else {
- GS.isNotSuitableForSRA = true;
- }
} else if (isa<SelectInst>(I)) {
if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
- GS.isNotSuitableForSRA = true;
} else if (PHINode *PN = dyn_cast<PHINode>(I)) {
// PHI nodes we can check just like select or GEP instructions, but we
// have to be careful about infinite recursion.
- if (PHIUsers.insert(PN).second) // Not already visited.
+ if (PHIUsers.insert(PN)) // Not already visited.
if (AnalyzeGlobal(I, GS, PHIUsers)) return true;
- GS.isNotSuitableForSRA = true;
GS.HasPHIUser = true;
} else if (isa<CmpInst>(I)) {
- GS.isNotSuitableForSRA = true;
} else if (isa<MemCpyInst>(I) || isa<MemMoveInst>(I)) {
if (I->getOperand(1) == V)
GS.StoredType = GlobalStatus::isStored;
if (I->getOperand(2) == V)
GS.isLoaded = true;
- GS.isNotSuitableForSRA = true;
} else if (isa<MemSetInst>(I)) {
assert(I->getOperand(1) == V && "Memset only takes one pointer!");
GS.StoredType = GlobalStatus::isStored;
- GS.isNotSuitableForSRA = true;
} else {
return true; // Any other non-load instruction might take address!
}
} else if (Constant *C = dyn_cast<Constant>(U)) {
// If we have a chain of dead constantexprs or other things dangling from
// us, and if they are all dead, nuke them without remorse.
- if (ConstantIsDead(C)) {
+ SmallPtrSet<GlobalVariable *, 4> DeadGVs;
+ if (ConstantIsDead(C, &DeadGVs)) {
+ for (SmallPtrSet<GlobalVariable *, 4>::iterator TI = DeadGVs.begin(),
+ TE = DeadGVs.end(); TI != TE; ) {
+ GlobalVariable *TGV = *TI; ++TI;
+ TGV->eraseFromParent();
+ }
C->destroyConstant();
// This could have invalidated UI, start over from scratch.
CleanupConstantGlobalUsers(V, Init);
return Changed;
}
+/// isSafeSROAElementUse - Return true if the specified instruction is a safe
+/// user of a derived expression from a global that we want to SROA.
+static bool isSafeSROAElementUse(Value *V) {
+ // We might have a dead and dangling constant hanging off of here.
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantIsDead(C);
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ // Loads are ok.
+ if (isa<LoadInst>(I)) return true;
+
+ // Stores *to* the pointer are ok.
+ if (StoreInst *SI = dyn_cast<StoreInst>(I))
+ return SI->getOperand(0) != V;
+
+ // Otherwise, it must be a GEP.
+ GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I);
+ if (GEPI == 0) return false;
+
+ if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) ||
+ !cast<Constant>(GEPI->getOperand(1))->isNullValue())
+ return false;
+
+ for (Value::use_iterator I = GEPI->use_begin(), E = GEPI->use_end();
+ I != E; ++I)
+ if (!isSafeSROAElementUse(*I))
+ return false;
+ return true;
+}
+
-/// UsersSafeToSRA - Look at all uses of the global and decide whether it is
-/// safe for us to perform this transformation.
+/// IsUserOfGlobalSafeForSRA - U is a direct user of the specified global value.
+/// Look at it and its uses and decide whether it is safe to SROA this global.
///
-static bool UsersSafeToSRA(Value *V) {
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
- if (CE->getOpcode() != Instruction::GetElementPtr)
- return false;
+static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) {
+ // The user of the global must be a GEP Inst or a ConstantExpr GEP.
+ if (!isa<GetElementPtrInst>(U) &&
+ (!isa<ConstantExpr>(U) ||
+ cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr))
+ return false;
+
+ // Check to see if this ConstantExpr GEP is SRA'able. In particular, we
+ // don't like < 3 operand CE's, and we don't like non-constant integer
+ // indices. This enforces that all uses are 'gep GV, 0, C, ...' for some
+ // value of C.
+ if (U->getNumOperands() < 3 || !isa<Constant>(U->getOperand(1)) ||
+ !cast<Constant>(U->getOperand(1))->isNullValue() ||
+ !isa<ConstantInt>(U->getOperand(2)))
+ return false;
- // Check to see if this ConstantExpr GEP is SRA'able. In particular, we
- // don't like < 3 operand CE's, and we don't like non-constant integer
- // indices.
- if (CE->getNumOperands() < 3 || !CE->getOperand(1)->isNullValue())
- return false;
-
- for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
- if (!isa<ConstantInt>(CE->getOperand(i)))
- return false;
-
- if (!UsersSafeToSRA(CE)) return false;
- continue;
- }
+ gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U);
+ ++GEPI; // Skip over the pointer index.
+
+ // If this is a use of an array allocation, do a bit more checking for sanity.
+ if (const ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) {
+ uint64_t NumElements = AT->getNumElements();
+ ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2));
- if (Instruction *I = dyn_cast<Instruction>(*UI)) {
- if (isa<LoadInst>(I)) continue;
+ // Check to make sure that index falls within the array. If not,
+ // something funny is going on, so we won't do the optimization.
+ //
+ if (Idx->getZExtValue() >= NumElements)
+ return false;
- if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
- // Don't allow a store OF the address, only stores TO the address.
- if (SI->getOperand(0) == V) return false;
- continue;
- }
+ // We cannot scalar repl this level of the array unless any array
+ // sub-indices are in-range constants. In particular, consider:
+ // A[0][i]. We cannot know that the user isn't doing invalid things like
+ // allowing i to index an out-of-range subscript that accesses A[1].
+ //
+ // Scalar replacing *just* the outer index of the array is probably not
+ // going to be a win anyway, so just give up.
+ for (++GEPI; // Skip array index.
+ GEPI != E && (isa<ArrayType>(*GEPI) || isa<VectorType>(*GEPI));
+ ++GEPI) {
+ uint64_t NumElements;
+ if (const ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI))
+ NumElements = SubArrayTy->getNumElements();
+ else
+ NumElements = cast<VectorType>(*GEPI)->getNumElements();
- if (isa<GetElementPtrInst>(I)) {
- if (!UsersSafeToSRA(I)) return false;
-
- // If the first two indices are constants, this can be SRA'd.
- if (isa<GlobalVariable>(I->getOperand(0))) {
- if (I->getNumOperands() < 3 || !isa<Constant>(I->getOperand(1)) ||
- !cast<Constant>(I->getOperand(1))->isNullValue() ||
- !isa<ConstantInt>(I->getOperand(2)))
- return false;
- continue;
- }
-
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I->getOperand(0))){
- if (CE->getOpcode() != Instruction::GetElementPtr ||
- CE->getNumOperands() < 3 || I->getNumOperands() < 2 ||
- !isa<Constant>(I->getOperand(0)) ||
- !cast<Constant>(I->getOperand(0))->isNullValue())
- return false;
- continue;
- }
+ ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand());
+ if (!IdxVal || IdxVal->getZExtValue() >= NumElements)
return false;
- }
- return false; // Any other instruction is not safe.
}
- if (Constant *C = dyn_cast<Constant>(*UI)) {
- // We might have a dead and dangling constant hanging off of here.
- if (!ConstantIsDead(C))
- return false;
- continue;
- }
- // Otherwise must be some other user.
- return false;
}
-
+
+ for (Value::use_iterator I = U->use_begin(), E = U->use_end(); I != E; ++I)
+ if (!isSafeSROAElementUse(*I))
+ return false;
return true;
}
+/// GlobalUsersSafeToSRA - Look at all uses of the global and decide whether it
+/// is safe for us to perform this transformation.
+///
+static bool GlobalUsersSafeToSRA(GlobalValue *GV) {
+ for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end();
+ UI != E; ++UI) {
+ if (!IsUserOfGlobalSafeForSRA(*UI, GV))
+ return false;
+ }
+ return true;
+}
+
+
/// SRAGlobal - Perform scalar replacement of aggregates on the specified global
/// variable. This opens the door for other optimizations by exposing the
/// behavior of the program in a more fine-grained way. We have determined that
/// this transformation is safe already. We return the first global variable we
/// insert so that the caller can reprocess it.
-static GlobalVariable *SRAGlobal(GlobalVariable *GV) {
+static GlobalVariable *SRAGlobal(GlobalVariable *GV, const TargetData &TD) {
// Make sure this global only has simple uses that we can SRA.
- if (!UsersSafeToSRA(GV))
+ if (!GlobalUsersSafeToSRA(GV))
return 0;
- assert(GV->hasInternalLinkage() && !GV->isConstant());
+ assert(GV->hasLocalLinkage() && !GV->isConstant());
Constant *Init = GV->getInitializer();
const Type *Ty = Init->getType();
std::vector<GlobalVariable*> NewGlobals;
Module::GlobalListType &Globals = GV->getParent()->getGlobalList();
+ // Get the alignment of the global, either explicit or target-specific.
+ unsigned StartAlignment = GV->getAlignment();
+ if (StartAlignment == 0)
+ StartAlignment = TD.getABITypeAlignment(GV->getType());
+
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
NewGlobals.reserve(STy->getNumElements());
+ const StructLayout &Layout = *TD.getStructLayout(STy);
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Constant *In = getAggregateConstantElement(Init,
ConstantInt::get(Type::Int32Ty, i));
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+utostr(i),
(Module *)NULL,
- GV->isThreadLocal());
+ GV->isThreadLocal(),
+ GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
+
+ // Calculate the known alignment of the field. If the original aggregate
+ // had 256 byte alignment for example, something might depend on that:
+ // propagate info to each field.
+ uint64_t FieldOffset = Layout.getElementOffset(i);
+ unsigned NewAlign = (unsigned)MinAlign(StartAlignment, FieldOffset);
+ if (NewAlign > TD.getABITypeAlignment(STy->getElementType(i)))
+ NGV->setAlignment(NewAlign);
}
} else if (const SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
unsigned NumElements = 0;
if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
NumElements = ATy->getNumElements();
- else if (const VectorType *PTy = dyn_cast<VectorType>(STy))
- NumElements = PTy->getNumElements();
else
- assert(0 && "Unknown aggregate sequential type!");
+ NumElements = cast<VectorType>(STy)->getNumElements();
if (NumElements > 16 && GV->hasNUsesOrMore(16))
return 0; // It's not worth it.
NewGlobals.reserve(NumElements);
+
+ uint64_t EltSize = TD.getTypePaddedSize(STy->getElementType());
+ unsigned EltAlign = TD.getABITypeAlignment(STy->getElementType());
for (unsigned i = 0, e = NumElements; i != e; ++i) {
Constant *In = getAggregateConstantElement(Init,
ConstantInt::get(Type::Int32Ty, i));
GlobalVariable::InternalLinkage,
In, GV->getName()+"."+utostr(i),
(Module *)NULL,
- GV->isThreadLocal());
+ GV->isThreadLocal(),
+ GV->getType()->getAddressSpace());
Globals.insert(GV, NGV);
NewGlobals.push_back(NGV);
+
+ // Calculate the known alignment of the field. If the original aggregate
+ // had 256 byte alignment for example, something might depend on that:
+ // propagate info to each field.
+ unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i);
+ if (NewAlign > EltAlign)
+ NGV->setAlignment(NewAlign);
}
}
Value *NewPtr = NewGlobals[Val];
// Form a shorter GEP if needed.
- if (GEP->getNumOperands() > 3)
+ if (GEP->getNumOperands() > 3) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP)) {
SmallVector<Constant*, 8> Idxs;
Idxs.push_back(NullInt);
Idxs.push_back(NullInt);
for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i)
Idxs.push_back(GEPI->getOperand(i));
- NewPtr = new GetElementPtrInst(NewPtr, Idxs.begin(), Idxs.end(),
- GEPI->getName()+"."+utostr(Val), GEPI);
+ NewPtr = GetElementPtrInst::Create(NewPtr, Idxs.begin(), Idxs.end(),
+ GEPI->getName()+"."+utostr(Val), GEPI);
}
+ }
GEP->replaceAllUsesWith(NewPtr);
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(GEP))
// Should handle GEP here.
SmallVector<Constant*, 8> Idxs;
Idxs.reserve(GEPI->getNumOperands()-1);
- for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
- if (Constant *C = dyn_cast<Constant>(GEPI->getOperand(i)))
+ 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 the loaded value is dynamically null, then we know that they cannot be
/// reachable with a null optimize away the load.
static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV) {
- std::vector<LoadInst*> Loads;
bool Changed = false;
+ // Keep track of whether we are able to remove all the uses of the global
+ // other than the store that defines it.
+ bool AllNonStoreUsesGone = true;
+
// Replace all uses of loads with uses of uses of the stored value.
- for (Value::use_iterator GUI = GV->use_begin(), E = GV->use_end();
- GUI != E; ++GUI)
- if (LoadInst *LI = dyn_cast<LoadInst>(*GUI)) {
- Loads.push_back(LI);
+ for (Value::use_iterator GUI = GV->use_begin(), E = GV->use_end(); GUI != E;){
+ User *GlobalUser = *GUI++;
+ if (LoadInst *LI = dyn_cast<LoadInst>(GlobalUser)) {
Changed |= OptimizeAwayTrappingUsesOfValue(LI, LV);
+ // If we were able to delete all uses of the loads
+ if (LI->use_empty()) {
+ LI->eraseFromParent();
+ Changed = true;
+ } else {
+ AllNonStoreUsesGone = false;
+ }
+ } else if (isa<StoreInst>(GlobalUser)) {
+ // Ignore the store that stores "LV" to the global.
+ assert(GlobalUser->getOperand(1) == GV &&
+ "Must be storing *to* the global");
} else {
- // If we get here we could have stores, selects, or phi nodes whose values
- // are loaded.
- assert((isa<StoreInst>(*GUI) || isa<PHINode>(*GUI) ||
- isa<SelectInst>(*GUI) || isa<ConstantExpr>(*GUI)) &&
- "Only expect load and stores!");
+ AllNonStoreUsesGone = false;
+
+ // If we get here we could have other crazy uses that are transitively
+ // loaded.
+ assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) ||
+ isa<ConstantExpr>(GlobalUser)) && "Only expect load and stores!");
}
+ }
if (Changed) {
DOUT << "OPTIMIZED LOADS FROM STORED ONCE POINTER: " << *GV;
++NumGlobUses;
}
- // Delete all of the loads we can, keeping track of whether we nuked them all!
- bool AllLoadsGone = true;
- while (!Loads.empty()) {
- LoadInst *L = Loads.back();
- if (L->use_empty()) {
- L->eraseFromParent();
- Changed = true;
- } else {
- AllLoadsGone = false;
- }
- Loads.pop_back();
- }
-
// If we nuked all of the loads, then none of the stores are needed either,
// nor is the global.
- if (AllLoadsGone) {
+ if (AllNonStoreUsesGone) {
DOUT << " *** GLOBAL NOW DEAD!\n";
CleanupConstantGlobalUsers(GV, 0);
if (GV->use_empty()) {
MI->getAlignment(), MI->getName(), MI);
Value* Indices[2];
Indices[0] = Indices[1] = Constant::getNullValue(Type::Int32Ty);
- Value *NewGEP = new GetElementPtrInst(NewMI, Indices, Indices + 2,
- NewMI->getName()+".el0", MI);
+ Value *NewGEP = GetElementPtrInst::Create(NewMI, Indices, Indices + 2,
+ NewMI->getName()+".el0", MI);
MI->replaceAllUsesWith(NewGEP);
MI->eraseFromParent();
MI = NewMI;
GV->getName()+".body",
(Module *)NULL,
GV->isThreadLocal());
+ // FIXME: This new global should have the alignment returned by malloc. Code
+ // could depend on malloc returning large alignment (on the mac, 16 bytes) but
+ // this would only guarantee some lower alignment.
GV->getParent()->getGlobalList().insert(GV, NewGV);
// Anything that used the malloc now uses the global directly.
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE:
case ICmpInst::ICMP_EQ:
- LV = BinaryOperator::createNot(LV, "notinit", CI);
+ LV = BinaryOperator::CreateNot(LV, "notinit", CI);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGE:
static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
GlobalVariable *GV,
SmallPtrSet<PHINode*, 8> &PHIs) {
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
- if (isa<LoadInst>(*UI) || isa<CmpInst>(*UI)) {
- // Fine, ignore.
- } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
+ Instruction *Inst = dyn_cast<Instruction>(*UI);
+ if (Inst == 0) return false;
+
+ if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) {
+ continue; // Fine, ignore.
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (SI->getOperand(0) == V && SI->getOperand(1) != GV)
return false; // Storing the pointer itself... bad.
- // Otherwise, storing through it, or storing into GV... fine.
- } else if (isa<GetElementPtrInst>(*UI)) {
- if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(cast<Instruction>(*UI),
- GV, PHIs))
+ continue; // Otherwise, storing through it, or storing into GV... fine.
+ }
+
+ if (isa<GetElementPtrInst>(Inst)) {
+ if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs))
return false;
- } else if (PHINode *PN = dyn_cast<PHINode>(*UI)) {
+ continue;
+ }
+
+ if (PHINode *PN = dyn_cast<PHINode>(Inst)) {
// PHIs are ok if all uses are ok. Don't infinitely recurse through PHI
// cycles.
if (PHIs.insert(PN))
if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(PN, GV, PHIs))
return false;
- } else {
- return false;
+ continue;
+ }
+
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) {
+ if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs))
+ return false;
+ continue;
}
+
+ return false;
+ }
return true;
}
} else if (PHINode *PN = dyn_cast<PHINode>(U)) {
// Insert the load in the corresponding predecessor, not right before the
// PHI.
- unsigned PredNo = Alloc->use_begin().getOperandNo()/2;
- InsertPt = PN->getIncomingBlock(PredNo)->getTerminator();
+ InsertPt = PN->getIncomingBlock(Alloc->use_begin())->getTerminator();
+ } else if (isa<BitCastInst>(U)) {
+ // Must be bitcast between the malloc and store to initialize the global.
+ ReplaceUsesOfMallocWithGlobal(U, GV);
+ U->eraseFromParent();
+ continue;
+ } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) {
+ // If this is a "GEP bitcast" and the user is a store to the global, then
+ // just process it as a bitcast.
+ if (GEPI->hasAllZeroIndices() && GEPI->hasOneUse())
+ if (StoreInst *SI = dyn_cast<StoreInst>(GEPI->use_back()))
+ if (SI->getOperand(1) == GV) {
+ // Must be bitcast GEP between the malloc and store to initialize
+ // the global.
+ ReplaceUsesOfMallocWithGlobal(GEPI, GV);
+ GEPI->eraseFromParent();
+ continue;
+ }
}
-
+
// Insert a load from the global, and use it instead of the malloc.
Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt);
U->replaceUsesOfWith(Alloc, NL);
}
}
-/// GlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from
+/// LoadUsesSimpleEnoughForHeapSRA - Verify that all uses of V (a load, or a phi
+/// of a load) are simple enough to perform heap SRA on. This permits GEP's
+/// that index through the array and struct field, icmps of null, and PHIs.
+static bool LoadUsesSimpleEnoughForHeapSRA(Value *V,
+ SmallPtrSet<PHINode*, 32> &LoadUsingPHIs) {
+ // We permit two users of the load: setcc comparing against the null
+ // pointer, and a getelementptr of a specific form.
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
+ Instruction *User = cast<Instruction>(*UI);
+
+ // Comparison against null is ok.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(User)) {
+ if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
+ return false;
+ continue;
+ }
+
+ // getelementptr is also ok, but only a simple form.
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
+ // Must index into the array and into the struct.
+ if (GEPI->getNumOperands() < 3)
+ return false;
+
+ // Otherwise the GEP is ok.
+ continue;
+ }
+
+ if (PHINode *PN = dyn_cast<PHINode>(User)) {
+ // If we have already recursively analyzed this PHI, then it is safe.
+ if (LoadUsingPHIs.insert(PN))
+ continue;
+
+ // Make sure all uses of the PHI are simple enough to transform.
+ if (!LoadUsesSimpleEnoughForHeapSRA(PN, LoadUsingPHIs))
+ return false;
+
+ continue;
+ }
+
+ // Otherwise we don't know what this is, not ok.
+ return false;
+ }
+
+ return true;
+}
+
+
+/// AllGlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from
/// GV are simple enough to perform HeapSRA, return true.
-static bool GlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
- MallocInst *MI) {
+static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(GlobalVariable *GV,
+ MallocInst *MI) {
+ SmallPtrSet<PHINode*, 32> LoadUsingPHIs;
for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;
++UI)
- if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
- // We permit two users of the load: setcc comparing against the null
- // pointer, and a getelementptr of a specific form.
- for (Value::use_iterator UI = LI->use_begin(), E = LI->use_end(); UI != E;
- ++UI) {
- // Comparison against null is ok.
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) {
- if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
- return false;
- continue;
- }
-
- // getelementptr is also ok, but only a simple form.
- if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) {
- // Must index into the array and into the struct.
- if (GEPI->getNumOperands() < 3)
- return false;
-
- // Otherwise the GEP is ok.
+ if (LoadInst *LI = dyn_cast<LoadInst>(*UI))
+ if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs))
+ return false;
+
+ // If we reach here, we know that all uses of the loads and transitive uses
+ // (through PHI nodes) are simple enough to transform. However, we don't know
+ // that all inputs the to the PHI nodes are in the same equivalence sets.
+ // Check to verify that all operands of the PHIs are either PHIS that can be
+ // transformed, loads from GV, or MI itself.
+ for (SmallPtrSet<PHINode*, 32>::iterator I = LoadUsingPHIs.begin(),
+ E = LoadUsingPHIs.end(); I != E; ++I) {
+ PHINode *PN = *I;
+ for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) {
+ Value *InVal = PN->getIncomingValue(op);
+
+ // PHI of the stored value itself is ok.
+ if (InVal == MI) continue;
+
+ if (PHINode *InPN = dyn_cast<PHINode>(InVal)) {
+ // One of the PHIs in our set is (optimistically) ok.
+ if (LoadUsingPHIs.count(InPN))
continue;
- }
-
- if (PHINode *PN = dyn_cast<PHINode>(*UI)) {
- // We have a phi of a load from the global. We can only handle this
- // if the other PHI'd values are actually the same. In this case,
- // the rewriter will just drop the phi entirely.
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- Value *IV = PN->getIncomingValue(i);
- if (IV == LI) continue; // Trivial the same.
-
- // If the phi'd value is from the malloc that initializes the value,
- // we can xform it.
- if (IV == MI) continue;
-
- // Otherwise, we don't know what it is.
- return false;
- }
- return true;
- }
-
- // Otherwise we don't know what this is, not ok.
return false;
}
+
+ // Load from GV is ok.
+ if (LoadInst *LI = dyn_cast<LoadInst>(InVal))
+ if (LI->getOperand(0) == GV)
+ continue;
+
+ // UNDEF? NULL?
+
+ // Anything else is rejected.
+ return false;
}
+ }
+
return true;
}
-/// GetHeapSROALoad - Return the load for the specified field of the HeapSROA'd
-/// value, lazily creating it on demand.
-static Value *GetHeapSROALoad(Instruction *Load, unsigned FieldNo,
- const std::vector<GlobalVariable*> &FieldGlobals,
- std::vector<Value *> &InsertedLoadsForPtr) {
- if (InsertedLoadsForPtr.size() <= FieldNo)
- InsertedLoadsForPtr.resize(FieldNo+1);
- if (InsertedLoadsForPtr[FieldNo] == 0)
- InsertedLoadsForPtr[FieldNo] = new LoadInst(FieldGlobals[FieldNo],
- Load->getName()+".f" +
- utostr(FieldNo), Load);
- return InsertedLoadsForPtr[FieldNo];
+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 we already have this value, just reuse the previously scalarized
+ // version.
+ if (Value *FieldVal = FieldVals[FieldNo])
+ return FieldVal;
+
+ // Depending on what instruction this is, we have several cases.
+ Value *Result;
+ if (LoadInst *LI = dyn_cast<LoadInst>(V)) {
+ // This is a scalarized version of the load from the global. Just create
+ // a new Load of the scalarized global.
+ Result = new LoadInst(GetHeapSROAValue(LI->getOperand(0), FieldNo,
+ InsertedScalarizedValues,
+ PHIsToRewrite),
+ LI->getName()+".f" + utostr(FieldNo), LI);
+ } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
+ // PN's type is pointer to struct. Make a new PHI of pointer to struct
+ // field.
+ const StructType *ST =
+ cast<StructType>(cast<PointerType>(PN->getType())->getElementType());
+
+ Result =PHINode::Create(PointerType::getUnqual(ST->getElementType(FieldNo)),
+ PN->getName()+".f"+utostr(FieldNo), PN);
+ PHIsToRewrite.push_back(std::make_pair(PN, FieldNo));
+ } else {
+ assert(0 && "Unknown usable value");
+ Result = 0;
+ }
+
+ return FieldVals[FieldNo] = Result;
}
/// RewriteHeapSROALoadUser - Given a load instruction and a value derived from
/// the load, rewrite the derived value to use the HeapSRoA'd load.
-static void RewriteHeapSROALoadUser(LoadInst *Load, Instruction *LoadUser,
- const std::vector<GlobalVariable*> &FieldGlobals,
- std::vector<Value *> &InsertedLoadsForPtr) {
+static void RewriteHeapSROALoadUser(Instruction *LoadUser,
+ DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
+ std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
// If this is a comparison against null, handle it.
if (ICmpInst *SCI = dyn_cast<ICmpInst>(LoadUser)) {
assert(isa<ConstantPointerNull>(SCI->getOperand(1)));
// If we have a setcc of the loaded pointer, we can use a setcc of any
// field.
- Value *NPtr;
- if (InsertedLoadsForPtr.empty()) {
- NPtr = GetHeapSROALoad(Load, 0, FieldGlobals, InsertedLoadsForPtr);
- } else {
- NPtr = InsertedLoadsForPtr.back();
- }
+ Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0,
+ InsertedScalarizedValues, PHIsToRewrite);
Value *New = new ICmpInst(SCI->getPredicate(), NPtr,
Constant::getNullValue(NPtr->getType()),
return;
}
- // Handle 'getelementptr Ptr, Idx, uint FieldNo ...'
+ // Handle 'getelementptr Ptr, Idx, i32 FieldNo ...'
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) {
assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2))
&& "Unexpected GEPI!");
// Load the pointer for this field.
unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
- Value *NewPtr = GetHeapSROALoad(Load, FieldNo,
- FieldGlobals, InsertedLoadsForPtr);
+ Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo,
+ InsertedScalarizedValues, PHIsToRewrite);
// Create the new GEP idx vector.
SmallVector<Value*, 8> GEPIdx;
GEPIdx.push_back(GEPI->getOperand(1));
GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end());
- Value *NGEPI = new GetElementPtrInst(NewPtr, GEPIdx.begin(), GEPIdx.end(),
- GEPI->getName(), GEPI);
+ Value *NGEPI = GetElementPtrInst::Create(NewPtr,
+ GEPIdx.begin(), GEPIdx.end(),
+ GEPI->getName(), GEPI);
GEPI->replaceAllUsesWith(NGEPI);
GEPI->eraseFromParent();
return;
}
-
- // Handle PHI nodes. PHI nodes must be merging in the same values, plus
- // potentially the original malloc. Insert phi nodes for each field, then
- // process uses of the PHI.
+
+ // Recursively transform the users of PHI nodes. This will lazily create the
+ // PHIs that are needed for individual elements. Keep track of what PHIs we
+ // see in InsertedScalarizedValues so that we don't get infinite loops (very
+ // antisocial). If the PHI is already in InsertedScalarizedValues, it has
+ // already been seen first by another load, so its uses have already been
+ // processed.
PHINode *PN = cast<PHINode>(LoadUser);
- std::vector<Value *> PHIsForField;
- PHIsForField.resize(FieldGlobals.size());
- for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
- Value *LoadV = GetHeapSROALoad(Load, i, FieldGlobals, InsertedLoadsForPtr);
-
- PHINode *FieldPN = new PHINode(LoadV->getType(),
- PN->getName()+"."+utostr(i), PN);
- // Fill in the predecessor values.
- for (unsigned pred = 0, e = PN->getNumIncomingValues(); pred != e; ++pred) {
- // Each predecessor either uses the load or the original malloc.
- Value *InVal = PN->getIncomingValue(pred);
- BasicBlock *BB = PN->getIncomingBlock(pred);
- Value *NewVal;
- if (isa<MallocInst>(InVal)) {
- // Insert a reload from the global in the predecessor.
- NewVal = GetHeapSROALoad(BB->getTerminator(), i, FieldGlobals,
- PHIsForField);
- } else {
- NewVal = InsertedLoadsForPtr[i];
- }
- FieldPN->addIncoming(NewVal, BB);
- }
- PHIsForField[i] = FieldPN;
- }
+ bool Inserted;
+ DenseMap<Value*, std::vector<Value*> >::iterator InsertPos;
+ tie(InsertPos, Inserted) =
+ InsertedScalarizedValues.insert(std::make_pair(PN, std::vector<Value*>()));
+ if (!Inserted) return;
- // Since PHIsForField specifies a phi for every input value, the lazy inserter
- // will never insert a load.
- while (!PN->use_empty())
- RewriteHeapSROALoadUser(Load, PN->use_back(), FieldGlobals, PHIsForField);
- PN->eraseFromParent();
+ // If this is the first time we've seen this PHI, recursively process all
+ // users.
+ for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E; ) {
+ Instruction *User = cast<Instruction>(*UI++);
+ RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
+ }
}
/// RewriteUsesOfLoadForHeapSRoA - We are performing Heap SRoA on a global. Ptr
/// is a value loaded from the global. Eliminate all uses of Ptr, making them
/// use FieldGlobals instead. All uses of loaded values satisfy
-/// GlobalLoadUsesSimpleEnoughForHeapSRA.
+/// AllGlobalLoadUsesSimpleEnoughForHeapSRA.
static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load,
- const std::vector<GlobalVariable*> &FieldGlobals) {
- std::vector<Value *> InsertedLoadsForPtr;
- //InsertedLoadsForPtr.resize(FieldGlobals.size());
- while (!Load->use_empty())
- RewriteHeapSROALoadUser(Load, Load->use_back(),
- FieldGlobals, InsertedLoadsForPtr);
+ DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues,
+ std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) {
+ for (Value::use_iterator UI = Load->use_begin(), E = Load->use_end();
+ UI != E; ) {
+ Instruction *User = cast<Instruction>(*UI++);
+ RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite);
+ }
+
+ if (Load->use_empty()) {
+ Load->eraseFromParent();
+ InsertedScalarizedValues.erase(Load);
+ }
}
/// PerformHeapAllocSRoA - MI is an allocation of an array of structures. Break
// Okay, at this point, there are no users of the malloc. Insert N
// new mallocs at the same place as MI, and N globals.
- std::vector<GlobalVariable*> FieldGlobals;
+ std::vector<Value*> FieldGlobals;
std::vector<MallocInst*> FieldMallocs;
for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){
if (!RunningOr)
RunningOr = Cond; // First seteq
else
- RunningOr = BinaryOperator::createOr(RunningOr, Cond, "tmp", MI);
+ RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", MI);
}
// Split the basic block at the old malloc.
// Create the block to check the first condition. Put all these blocks at the
// end of the function as they are unlikely to be executed.
- BasicBlock *NullPtrBlock = new BasicBlock("malloc_ret_null",
- OrigBB->getParent());
+ BasicBlock *NullPtrBlock = BasicBlock::Create("malloc_ret_null",
+ OrigBB->getParent());
// Remove the uncond branch from OrigBB to ContBB, turning it into a cond
// branch on RunningOr.
OrigBB->getTerminator()->eraseFromParent();
- new BranchInst(NullPtrBlock, ContBB, RunningOr, OrigBB);
+ BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB);
// Within the NullPtrBlock, we need to emit a comparison and branch for each
// pointer, because some may be null while others are not.
Value *Cmp = new ICmpInst(ICmpInst::ICMP_NE, GVVal,
Constant::getNullValue(GVVal->getType()),
"tmp", NullPtrBlock);
- BasicBlock *FreeBlock = new BasicBlock("free_it", OrigBB->getParent());
- BasicBlock *NextBlock = new BasicBlock("next", OrigBB->getParent());
- new BranchInst(FreeBlock, NextBlock, Cmp, NullPtrBlock);
+ BasicBlock *FreeBlock = BasicBlock::Create("free_it", OrigBB->getParent());
+ BasicBlock *NextBlock = BasicBlock::Create("next", OrigBB->getParent());
+ BranchInst::Create(FreeBlock, NextBlock, Cmp, NullPtrBlock);
// Fill in FreeBlock.
new FreeInst(GVVal, FreeBlock);
new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i],
FreeBlock);
- new BranchInst(NextBlock, FreeBlock);
+ BranchInst::Create(NextBlock, FreeBlock);
NullPtrBlock = NextBlock;
}
- new BranchInst(ContBB, NullPtrBlock);
-
+ BranchInst::Create(ContBB, NullPtrBlock);
// MI is no longer needed, remove it.
MI->eraseFromParent();
+ /// InsertedScalarizedLoads - As we process loads, if we can't immediately
+ /// update all uses of the load, keep track of what scalarized loads are
+ /// inserted for a given load.
+ DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues;
+ InsertedScalarizedValues[GV] = FieldGlobals;
+
+ std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite;
// Okay, the malloc site is completely handled. All of the uses of GV are now
// loads, and all uses of those loads are simple. Rewrite them to use loads
// of the per-field globals instead.
- while (!GV->use_empty()) {
- if (LoadInst *LI = dyn_cast<LoadInst>(GV->use_back())) {
- RewriteUsesOfLoadForHeapSRoA(LI, FieldGlobals);
- LI->eraseFromParent();
- } else {
- // Must be a store of null.
- StoreInst *SI = cast<StoreInst>(GV->use_back());
- assert(isa<Constant>(SI->getOperand(0)) &&
- cast<Constant>(SI->getOperand(0))->isNullValue() &&
- "Unexpected heap-sra user!");
-
- // Insert a store of null into each global.
- for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
- Constant *Null =
- Constant::getNullValue(FieldGlobals[i]->getType()->getElementType());
- new StoreInst(Null, FieldGlobals[i], SI);
- }
- // Erase the original store.
- SI->eraseFromParent();
+ for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI != E;) {
+ Instruction *User = cast<Instruction>(*UI++);
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
+ RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite);
+ continue;
+ }
+
+ // Must be a store of null.
+ StoreInst *SI = cast<StoreInst>(User);
+ assert(isa<ConstantPointerNull>(SI->getOperand(0)) &&
+ "Unexpected heap-sra user!");
+
+ // Insert a store of null into each global.
+ for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) {
+ const PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType());
+ Constant *Null = Constant::getNullValue(PT->getElementType());
+ new StoreInst(Null, FieldGlobals[i], SI);
}
+ // Erase the original store.
+ SI->eraseFromParent();
}
+ // While we have PHIs that are interesting to rewrite, do it.
+ 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");
+
+ // Add all the incoming values. This can materialize more phis.
+ 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));
+ }
+ }
+
+ // Drop all inter-phi links and any loads that made it this far.
+ 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();
+ }
+
+ // Delete all the phis and loads now that inter-references are dead.
+ 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();
+ }
+
// The old global is now dead, remove it.
GV->eraseFromParent();
++NumHeapSRA;
- return FieldGlobals[0];
+ return cast<GlobalVariable>(FieldGlobals[0]);
}
+/// TryToOptimizeStoreOfMallocToGlobal - This function is called when we see a
+/// pointer global variable with a single value stored it that is a malloc or
+/// cast of malloc.
+static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
+ MallocInst *MI,
+ Module::global_iterator &GVI,
+ TargetData &TD) {
+ // If this is a malloc of an abstract type, don't touch it.
+ if (!MI->getAllocatedType()->isSized())
+ return false;
+
+ // We can't optimize this global unless all uses of it are *known* to be
+ // of the malloc value, not of the null initializer value (consider a use
+ // that compares the global's value against zero to see if the malloc has
+ // been reached). To do this, we check to see if all uses of the global
+ // would trap if the global were null: this proves that they must all
+ // happen after the malloc.
+ if (!AllUsesOfLoadedValueWillTrapIfNull(GV))
+ return false;
+
+ // We can't optimize this if the malloc itself is used in a complex way,
+ // for example, being stored into multiple globals. This allows the
+ // malloc to be stored into the specified global, loaded setcc'd, and
+ // GEP'd. These are all things we could transform to using the global
+ // for.
+ {
+ SmallPtrSet<PHINode*, 8> PHIs;
+ if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV, PHIs))
+ return false;
+ }
+
+
+ // If we have a global that is only initialized with a fixed size malloc,
+ // transform the program to use global memory instead of malloc'd memory.
+ // This eliminates dynamic allocation, avoids an indirection accessing the
+ // data, and exposes the resultant global to further GlobalOpt.
+ if (ConstantInt *NElements = dyn_cast<ConstantInt>(MI->getArraySize())) {
+ // Restrict this transformation to only working on small allocations
+ // (2048 bytes currently), as we don't want to introduce a 16M global or
+ // something.
+ if (NElements->getZExtValue()*
+ TD.getTypePaddedSize(MI->getAllocatedType()) < 2048) {
+ GVI = OptimizeGlobalAddressOfMalloc(GV, MI);
+ return true;
+ }
+ }
+
+ // If the allocation is an array of structures, consider transforming this
+ // into multiple malloc'd arrays, one for each field. This is basically
+ // SRoA for malloc'd memory.
+ const Type *AllocTy = MI->getAllocatedType();
+
+ // If this is an allocation of a fixed size array of structs, analyze as a
+ // variable size array. malloc [100 x struct],1 -> malloc struct, 100
+ if (!MI->isArrayAllocation())
+ if (const ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
+ AllocTy = AT->getElementType();
+
+ if (const StructType *AllocSTy = dyn_cast<StructType>(AllocTy)) {
+ // This the structure has an unreasonable number of fields, leave it
+ // alone.
+ if (AllocSTy->getNumElements() <= 16 && AllocSTy->getNumElements() != 0 &&
+ AllGlobalLoadUsesSimpleEnoughForHeapSRA(GV, MI)) {
+
+ // If this is a fixed size array, transform the Malloc to be an alloc of
+ // structs. malloc [100 x struct],1 -> malloc struct, 100
+ if (const ArrayType *AT = dyn_cast<ArrayType>(MI->getAllocatedType())) {
+ MallocInst *NewMI =
+ new MallocInst(AllocSTy,
+ ConstantInt::get(Type::Int32Ty, AT->getNumElements()),
+ "", MI);
+ NewMI->takeName(MI);
+ Value *Cast = new BitCastInst(NewMI, MI->getType(), "tmp", MI);
+ MI->replaceAllUsesWith(Cast);
+ MI->eraseFromParent();
+ MI = NewMI;
+ }
+
+ GVI = PerformHeapAllocSRoA(GV, MI);
+ return true;
+ }
+ }
+
+ return false;
+}
// OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge
// that only one value (besides its initializer) is ever stored to the global.
static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
Module::global_iterator &GVI,
TargetData &TD) {
- if (CastInst *CI = dyn_cast<CastInst>(StoredOnceVal))
- StoredOnceVal = CI->getOperand(0);
- else if (GetElementPtrInst *GEPI =dyn_cast<GetElementPtrInst>(StoredOnceVal)){
- // "getelementptr Ptr, 0, 0, 0" is really just a cast.
- bool IsJustACast = true;
- for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
- if (!isa<Constant>(GEPI->getOperand(i)) ||
- !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
- IsJustACast = false;
- break;
- }
- if (IsJustACast)
- StoredOnceVal = GEPI->getOperand(0);
- }
+ // Ignore no-op GEPs and bitcasts.
+ StoredOnceVal = StoredOnceVal->stripPointerCasts();
// If we are dealing with a pointer global that is initialized to null and
// only has one (non-null) value stored into it, then we can optimize any
if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC))
return true;
} else if (MallocInst *MI = dyn_cast<MallocInst>(StoredOnceVal)) {
- // If this is a malloc of an abstract type, don't touch it.
- if (!MI->getAllocatedType()->isSized())
- return false;
-
- // We can't optimize this global unless all uses of it are *known* to be
- // of the malloc value, not of the null initializer value (consider a use
- // that compares the global's value against zero to see if the malloc has
- // been reached). To do this, we check to see if all uses of the global
- // would trap if the global were null: this proves that they must all
- // happen after the malloc.
- if (!AllUsesOfLoadedValueWillTrapIfNull(GV))
- return false;
-
- // We can't optimize this if the malloc itself is used in a complex way,
- // for example, being stored into multiple globals. This allows the
- // malloc to be stored into the specified global, loaded setcc'd, and
- // GEP'd. These are all things we could transform to using the global
- // for.
- {
- SmallPtrSet<PHINode*, 8> PHIs;
- if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(MI, GV, PHIs))
- return false;
- }
-
-
- // If we have a global that is only initialized with a fixed size malloc,
- // transform the program to use global memory instead of malloc'd memory.
- // This eliminates dynamic allocation, avoids an indirection accessing the
- // data, and exposes the resultant global to further GlobalOpt.
- if (ConstantInt *NElements = dyn_cast<ConstantInt>(MI->getArraySize())) {
- // Restrict this transformation to only working on small allocations
- // (2048 bytes currently), as we don't want to introduce a 16M global or
- // something.
- if (NElements->getZExtValue()*
- TD.getABITypeSize(MI->getAllocatedType()) < 2048) {
- GVI = OptimizeGlobalAddressOfMalloc(GV, MI);
- return true;
- }
- }
-
- // If the allocation is an array of structures, consider transforming this
- // into multiple malloc'd arrays, one for each field. This is basically
- // SRoA for malloc'd memory.
- if (const StructType *AllocTy =
- dyn_cast<StructType>(MI->getAllocatedType())) {
- // This the structure has an unreasonable number of fields, leave it
- // alone.
- if (AllocTy->getNumElements() <= 16 && AllocTy->getNumElements() > 0 &&
- GlobalLoadUsesSimpleEnoughForHeapSRA(GV, MI)) {
- GVI = PerformHeapAllocSRoA(GV, MI);
- return true;
- }
- }
+ if (TryToOptimizeStoreOfMallocToGlobal(GV, MI, GVI, TD))
+ return true;
}
}
if (IsOneZero)
NSI = new ZExtInst(NLI, LI->getType(), "", LI);
else
- NSI = new SelectInst(NLI, OtherVal, InitVal, "", LI);
+ NSI = SelectInst::Create(NLI, OtherVal, InitVal, "", LI);
NSI->takeName(LI);
LI->replaceAllUsesWith(NSI);
}
/// it if possible. If we make a change, return true.
bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
Module::global_iterator &GVI) {
- std::set<PHINode*> PHIUsers;
+ SmallPtrSet<PHINode*, 16> PHIUsers;
GlobalStatus GS;
GV->removeDeadConstantUsers();
cerr << " HasMultipleAccessingFunctions = "
<< GS.HasMultipleAccessingFunctions << "\n";
cerr << " HasNonInstructionUser = " << GS.HasNonInstructionUser<<"\n";
- cerr << " isNotSuitableForSRA = " << GS.isNotSuitableForSRA << "\n";
cerr << "\n";
#endif
// this global a local variable) we replace the global with a local alloca
// in this function.
//
- // NOTE: It doesn't make sense to promote non first class types since we
+ // NOTE: It doesn't make sense to promote non single-value types since we
// are just replacing static memory to stack memory.
if (!GS.HasMultipleAccessingFunctions &&
GS.AccessingFunction && !GS.HasNonInstructionUser &&
- GV->getType()->getElementType()->isFirstClassType() &&
+ GV->getType()->getElementType()->isSingleValueType() &&
GS.AccessingFunction->getName() == "main" &&
GS.AccessingFunction->hasExternalLinkage()) {
DOUT << "LOCALIZING GLOBAL: " << *GV;
++NumMarked;
return true;
- } else if (!GV->getInitializer()->getType()->isFirstClassType()) {
- if (GlobalVariable *FirstNewGV = SRAGlobal(GV)) {
+ } else if (!GV->getInitializer()->getType()->isSingleValueType()) {
+ if (GlobalVariable *FirstNewGV = SRAGlobal(GV,
+ getAnalysis<TargetData>())) {
GVI = FirstNewGV; // Don't skip the newly produced globals!
return true;
}
} else if (GS.StoredType == GlobalStatus::isStoredOnce) {
// If the initial value for the global was an undef value, and if only
// one other value was stored into it, we can just change the
- // initializer to be an undef value, then delete all stores to the
+ // initializer to be the stored value, then delete all stores to the
// global. This allows us to mark it constant.
if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
if (isa<UndefValue>(GV->getInitializer())) {
if (!isa<CallInst>(User) && !isa<InvokeInst>(User)) return false;
// See if the function address is passed as an argument.
- for (unsigned i = 1, e = User->getNumOperands(); i != e; ++i)
- if (User->getOperand(i) == F) return false;
+ for (User::op_iterator i = User->op_begin() + 1, e = User->op_end();
+ i != e; ++i)
+ if (*i == F) return false;
}
return true;
}
/// function, changing them to FastCC.
static void ChangeCalleesToFastCall(Function *F) {
for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
- Instruction *User = cast<Instruction>(*UI);
- if (CallInst *CI = dyn_cast<CallInst>(User))
- CI->setCallingConv(CallingConv::Fast);
- else
- cast<InvokeInst>(User)->setCallingConv(CallingConv::Fast);
+ CallSite User(cast<Instruction>(*UI));
+ User.setCallingConv(CallingConv::Fast);
+ }
+}
+
+static AttrListPtr StripNest(const AttrListPtr &Attrs) {
+ for (unsigned i = 0, e = Attrs.getNumSlots(); i != e; ++i) {
+ if ((Attrs.getSlot(i).Attrs & Attribute::Nest) == 0)
+ continue;
+
+ // There can be only one.
+ return Attrs.removeAttr(Attrs.getSlot(i).Index, Attribute::Nest);
+ }
+
+ return Attrs;
+}
+
+static void RemoveNestAttribute(Function *F) {
+ F->setAttributes(StripNest(F->getAttributes()));
+ for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
+ CallSite User(cast<Instruction>(*UI));
+ User.setAttributes(StripNest(User.getAttributes()));
}
}
for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
Function *F = FI++;
F->removeDeadConstantUsers();
- if (F->use_empty() && (F->hasInternalLinkage() ||
+ if (F->use_empty() && (F->hasLocalLinkage() ||
F->hasLinkOnceLinkage())) {
M.getFunctionList().erase(F);
Changed = true;
++NumFnDeleted;
- } else if (F->hasInternalLinkage() &&
- F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
- OnlyCalledDirectly(F)) {
- // If this function has C calling conventions, is not a varargs
- // function, and is only called directly, promote it to use the Fast
- // calling convention.
- F->setCallingConv(CallingConv::Fast);
- ChangeCalleesToFastCall(F);
- ++NumFastCallFns;
- Changed = true;
+ } else if (F->hasLocalLinkage()) {
+ if (F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
+ OnlyCalledDirectly(F)) {
+ // If this function has C calling conventions, is not a varargs
+ // function, and is only called directly, promote it to use the Fast
+ // calling convention.
+ F->setCallingConv(CallingConv::Fast);
+ ChangeCalleesToFastCall(F);
+ ++NumFastCallFns;
+ Changed = true;
+ }
+
+ if (F->getAttributes().hasAttrSomewhere(Attribute::Nest) &&
+ OnlyCalledDirectly(F)) {
+ // The function is not used by a trampoline intrinsic, so it is safe
+ // to remove the 'nest' attribute.
+ RemoveNestAttribute(F);
+ ++NumNestRemoved;
+ Changed = true;
+ }
}
}
return Changed;
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
- if (!GV->isConstant() && GV->hasInternalLinkage() &&
+ if (!GV->isConstant() && GV->hasLocalLinkage() &&
GV->hasInitializer())
Changed |= ProcessInternalGlobal(GV, GVI);
}
if (!I->hasInitializer()) return 0;
ConstantArray *CA = dyn_cast<ConstantArray>(I->getInitializer());
if (!CA) return 0;
- for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
- if (ConstantStruct *CS = dyn_cast<ConstantStruct>(CA->getOperand(i))) {
+ for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(*i)) {
if (isa<ConstantPointerNull>(CS->getOperand(1)))
continue;
ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
std::vector<Function*> Result;
Result.reserve(CA->getNumOperands());
- for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
- ConstantStruct *CS = cast<ConstantStruct>(CA->getOperand(i));
+ for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
+ ConstantStruct *CS = cast<ConstantStruct>(*i);
Result.push_back(dyn_cast<Function>(CS->getOperand(1)));
}
return Result;
}
-static Constant *getVal(std::map<Value*, Constant*> &ComputedValues,
+static Constant *getVal(DenseMap<Value*, Constant*> &ComputedValues,
Value *V) {
if (Constant *CV = dyn_cast<Constant>(V)) return CV;
Constant *R = ComputedValues[V];
/// globals. This should be kept up to date with CommitValueTo.
static bool isSimpleEnoughPointerToCommit(Constant *C) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
- if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
+ if (!GV->hasExternalLinkage() && !GV->hasLocalLinkage())
return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
return !GV->isDeclaration(); // reject external globals.
}
if (CE->getOpcode() == Instruction::GetElementPtr &&
isa<GlobalVariable>(CE->getOperand(0))) {
GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
- if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
+ if (!GV->hasExternalLinkage() && !GV->hasLocalLinkage())
return false; // do not allow weak/linkonce/dllimport/dllexport linkage.
return GV->hasInitializer() &&
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
// Break up the constant into its elements.
if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
- for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i)
- Elts.push_back(CS->getOperand(i));
+ for (User::op_iterator i = CS->op_begin(), e = CS->op_end(); i != e; ++i)
+ Elts.push_back(cast<Constant>(*i));
} else if (isa<ConstantAggregateZero>(Init)) {
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
Elts.push_back(Constant::getNullValue(STy->getElementType(i)));
// Break up the array into elements.
std::vector<Constant*> Elts;
if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
- for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
- Elts.push_back(CA->getOperand(i));
+ for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i)
+ Elts.push_back(cast<Constant>(*i));
} else if (isa<ConstantAggregateZero>(Init)) {
Constant *Elt = Constant::getNullValue(ATy->getElementType());
Elts.assign(ATy->getNumElements(), Elt);
/// P after the stores reflected by 'memory' have been performed. If we can't
/// decide, return null.
static Constant *ComputeLoadResult(Constant *P,
- const std::map<Constant*, Constant*> &Memory) {
+ const DenseMap<Constant*, Constant*> &Memory) {
// If this memory location has been recently stored, use the stored value: it
// is the most up-to-date.
- std::map<Constant*, Constant*>::const_iterator I = Memory.find(P);
+ DenseMap<Constant*, Constant*>::const_iterator I = Memory.find(P);
if (I != Memory.end()) return I->second;
// Access it.
static bool EvaluateFunction(Function *F, Constant *&RetVal,
const std::vector<Constant*> &ActualArgs,
std::vector<Function*> &CallStack,
- std::map<Constant*, Constant*> &MutatedMemory,
+ DenseMap<Constant*, Constant*> &MutatedMemory,
std::vector<GlobalVariable*> &AllocaTmps) {
// Check to see if this function is already executing (recursion). If so,
// bail out. TODO: we might want to accept limited recursion.
CallStack.push_back(F);
/// Values - As we compute SSA register values, we store their contents here.
- std::map<Value*, Constant*> Values;
+ DenseMap<Value*, Constant*> Values;
// Initialize arguments to the incoming values specified.
unsigned ArgNo = 0;
/// ExecutedBlocks - We only handle non-looping, non-recursive code. As such,
/// we can only evaluate any one basic block at most once. This set keeps
/// track of what we have executed so we can detect recursive cases etc.
- std::set<BasicBlock*> ExecutedBlocks;
+ SmallPtrSet<BasicBlock*, 32> ExecutedBlocks;
// CurInst - The current instruction we're evaluating.
BasicBlock::iterator CurInst = F->begin()->begin();
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
Constant *P = getVal(Values, GEP->getOperand(0));
SmallVector<Constant*, 8> GEPOps;
- for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
- GEPOps.push_back(getVal(Values, GEP->getOperand(i)));
+ for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end();
+ i != e; ++i)
+ GEPOps.push_back(getVal(Values, *i));
InstResult = ConstantExpr::getGetElementPtr(P, &GEPOps[0], GEPOps.size());
} else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
if (LI->isVolatile()) return false; // no volatile accesses.
if (!Callee) return false; // Cannot resolve.
std::vector<Constant*> Formals;
- for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
- Formals.push_back(getVal(Values, CI->getOperand(i)));
+ for (User::op_iterator i = CI->op_begin() + 1, e = CI->op_end();
+ i != e; ++i)
+ Formals.push_back(getVal(Values, *i));
if (Callee->isDeclaration()) {
// If this is a function we can constant fold, do it.
// Okay, we succeeded in evaluating this control flow. See if we have
// executed the new block before. If so, we have a looping function,
// which we cannot evaluate in reasonable time.
- if (!ExecutedBlocks.insert(NewBB).second)
+ if (!ExecutedBlocks.insert(NewBB))
return false; // looped!
// Okay, we have never been in this block before. Check to see if there
/// MutatedMemory - For each store we execute, we update this map. Loads
/// check this to get the most up-to-date value. If evaluation is successful,
/// this state is committed to the process.
- std::map<Constant*, Constant*> MutatedMemory;
+ DenseMap<Constant*, Constant*> MutatedMemory;
/// AllocaTmps - To 'execute' an alloca, we create a temporary global variable
/// to represent its body. This vector is needed so we can delete the
DOUT << "FULLY EVALUATED GLOBAL CTOR FUNCTION '"
<< F->getName() << "' to " << MutatedMemory.size()
<< " stores.\n";
- for (std::map<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
+ for (DenseMap<Constant*, Constant*>::iterator I = MutatedMemory.begin(),
E = MutatedMemory.end(); I != E; ++I)
CommitValueTo(I->second, I->first);
}
return true;
}
+bool GlobalOpt::ResolveAliases(Module &M) {
+ bool Changed = false;
+
+ for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
+ I != E;) {
+ Module::alias_iterator J = I++;
+ // If the aliasee may change at link time, nothing can be done - bail out.
+ if (J->mayBeOverridden())
+ continue;
+
+ Constant *Aliasee = J->getAliasee();
+ GlobalValue *Target = cast<GlobalValue>(Aliasee->stripPointerCasts());
+ Target->removeDeadConstantUsers();
+ bool hasOneUse = Target->hasOneUse() && Aliasee->hasOneUse();
+
+ // Make all users of the alias use the aliasee instead.
+ if (!J->use_empty()) {
+ J->replaceAllUsesWith(Aliasee);
+ ++NumAliasesResolved;
+ Changed = true;
+ }
+
+ // If the aliasee has internal linkage, give it the name and linkage
+ // of the alias, and delete the alias. This turns:
+ // define internal ... @f(...)
+ // @a = alias ... @f
+ // into:
+ // define ... @a(...)
+ if (!Target->hasLocalLinkage())
+ continue;
+
+ // The transform is only useful if the alias does not have internal linkage.
+ if (J->hasLocalLinkage())
+ continue;
+
+ // Do not perform the transform if multiple aliases potentially target the
+ // aliasee. This check also ensures that it is safe to replace the section
+ // and other attributes of the aliasee with those of the alias.
+ if (!hasOneUse)
+ continue;
+
+ // Give the aliasee the name, linkage and other attributes of the alias.
+ Target->takeName(J);
+ Target->setLinkage(J->getLinkage());
+ Target->GlobalValue::copyAttributesFrom(J);
+
+ // Delete the alias.
+ M.getAliasList().erase(J);
+ ++NumAliasesRemoved;
+ Changed = true;
+ }
+
+ return Changed;
+}
bool GlobalOpt::runOnModule(Module &M) {
bool Changed = false;
// Optimize non-address-taken globals.
LocalChange |= OptimizeGlobalVars(M);
+
+ // Resolve aliases, when possible.
+ LocalChange |= ResolveAliases(M);
Changed |= LocalChange;
}
projects / oota-llvm.git / blobdiff