/// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
/// M1 has all of the global variables. If M2 contains any functions that are
/// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
/// prune appropriate entries out of M1s list.
static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
DenseMap<const Value*, Value*> ValueMap) {
GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
!GV->use_empty()) return;
std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
if (!InitList) return;
for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
if (CS->getOperand(1)->isNullValue())
break; // Found a null terminator, stop here.
ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
int Priority = CI ? CI->getSExtValue() : 0;
Constant *FP = CS->getOperand(1);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
if (CE->isCast())
FP = CE->getOperand(0);
if (Function *F = dyn_cast<Function>(FP)) {
if (!F->isDeclaration())
M1Tors.push_back(std::make_pair(F, Priority));
else {
// Map to M2's version of the function.
F = cast<Function>(ValueMap[F]);
M2Tors.push_back(std::make_pair(F, Priority));
}
}
}
}
GV->eraseFromParent();
if (!M1Tors.empty()) {
Constant *M1Init = GetTorInit(M1Tors);
new GlobalVariable(*M1, M1Init->getType(), false,
GlobalValue::AppendingLinkage,
M1Init, GlobalName);
}
GV = M2->getNamedGlobal(GlobalName);
assert(GV && "Not a clone of M1?");
assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
GV->eraseFromParent();
if (!M2Tors.empty()) {
Constant *M2Init = GetTorInit(M2Tors);
new GlobalVariable(*M2, M2Init->getType(), false,
GlobalValue::AppendingLinkage,
M2Init, GlobalName);
}
}
bool StripDeadPrototypesPass::runOnModule(Module &M) {
bool MadeChange = false;
// Erase dead function prototypes.
for (Module::iterator I = M.begin(), E = M.end(); I != E; ) {
Function *F = I++;
// Function must be a prototype and unused.
if (F->isDeclaration() && F->use_empty()) {
F->eraseFromParent();
++NumDeadPrototypes;
MadeChange = true;
}
}
// Erase dead global var prototypes.
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ) {
GlobalVariable *GV = I++;
// Global must be a prototype and unused.
if (GV->isDeclaration() && GV->use_empty())
GV->eraseFromParent();
}
// Return an indication of whether we changed anything or not.
return MadeChange;
}
static void rewriteTlsVars(Module &M, std::vector<VarInfo> *TlsVars,
PointerType *TemplatePtrType) {
// Set up the intrinsic that reads the thread pointer.
Function *ReadTpFunc = Intrinsic::getDeclaration(&M, Intrinsic::nacl_read_tp);
for (std::vector<VarInfo>::iterator VarInfo = TlsVars->begin();
VarInfo != TlsVars->end();
++VarInfo) {
GlobalVariable *Var = VarInfo->TlsVar;
while (!Var->use_empty()) {
Use *U = &Var->use_begin().getUse();
Instruction *InsertPt = PhiSafeInsertPt(U);
Value *RawThreadPtr = CallInst::Create(ReadTpFunc, "tls_raw", InsertPt);
Value *TypedThreadPtr = new BitCastInst(RawThreadPtr, TemplatePtrType,
"tls_struct", InsertPt);
SmallVector<Value*, 3> Indexes;
// We use -1 because we use the x86-style TLS layout in which
// the TLS data is stored at addresses below the thread pointer.
// This is largely because a check in nacl_irt_thread_create()
// in irt/irt_thread.c requires the thread pointer to be a
// self-pointer on x86-32.
// TODO(mseaborn): I intend to remove that check because it is
// non-portable. In the mean time, we want PNaCl pexes to work
// in older Chromium releases when translated to nexes.
Indexes.push_back(ConstantInt::get(
M.getContext(), APInt(32, -1)));
Indexes.push_back(ConstantInt::get(
M.getContext(), APInt(32, VarInfo->IsBss ? 1 : 0)));
Indexes.push_back(ConstantInt::get(
M.getContext(), APInt(32, VarInfo->TemplateIndex)));
Value *TlsField = GetElementPtrInst::Create(TypedThreadPtr, Indexes,
"field", InsertPt);
PhiSafeReplaceUses(U, TlsField);
}
VarInfo->TlsVar->eraseFromParent();
}
}
bool ConstantMerge::runOnModule(Module &M) {
TD = getAnalysisIfAvailable<TargetData>();
// Find all the globals that are marked "used". These cannot be merged.
SmallPtrSet<const GlobalValue*, 8> UsedGlobals;
FindUsedValues(M.getGlobalVariable("llvm.used"), UsedGlobals);
FindUsedValues(M.getGlobalVariable("llvm.compiler.used"), UsedGlobals);
// Map unique <constants, has-unknown-alignment> pairs to globals. We don't
// want to merge globals of unknown alignment with those of explicit
// alignment. If we have TargetData, we always know the alignment.
DenseMap<PointerIntPair<Constant*, 1, bool>, GlobalVariable*> CMap;
// Replacements - This vector contains a list of replacements to perform.
SmallVector<std::pair<GlobalVariable*, GlobalVariable*>, 32> Replacements;
bool MadeChange = false;
// Iterate constant merging while we are still making progress. Merging two
// constants together may allow us to merge other constants together if the
// second level constants have initializers which point to the globals that
// were just merged.
while (1) {
// First: Find the canonical constants others will be merged with.
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
// If this GV is dead, remove it.
GV->removeDeadConstantUsers();
if (GV->use_empty() && GV->hasLocalLinkage()) {
GV->eraseFromParent();
continue;
}
// Only process constants with initializers in the default address space.
if (!GV->isConstant() || !GV->hasDefinitiveInitializer() ||
GV->getType()->getAddressSpace() != 0 || GV->hasSection() ||
// Don't touch values marked with attribute(used).
UsedGlobals.count(GV))
continue;
// This transformation is legal for weak ODR globals in the sense it
// doesn't change semantics, but we really don't want to perform it
// anyway; it's likely to pessimize code generation, and some tools
// (like the Darwin linker in cases involving CFString) don't expect it.
if (GV->isWeakForLinker())
continue;
Constant *Init = GV->getInitializer();
// Check to see if the initializer is already known.
PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV));
GlobalVariable *&Slot = CMap[Pair];
// If this is the first constant we find or if the old one is local,
// replace with the current one. If the current is externally visible
// it cannot be replace, but can be the canonical constant we merge with.
if (Slot == 0 || IsBetterCannonical(*GV, *Slot))
Slot = GV;
}
// Second: identify all globals that can be merged together, filling in
// the Replacements vector. We cannot do the replacement in this pass
// because doing so may cause initializers of other globals to be rewritten,
// invalidating the Constant* pointers in CMap.
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
// Only process constants with initializers in the default address space.
if (!GV->isConstant() || !GV->hasDefinitiveInitializer() ||
GV->getType()->getAddressSpace() != 0 || GV->hasSection() ||
// Don't touch values marked with attribute(used).
UsedGlobals.count(GV))
continue;
// We can only replace constant with local linkage.
if (!GV->hasLocalLinkage())
continue;
Constant *Init = GV->getInitializer();
// Check to see if the initializer is already known.
PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV));
GlobalVariable *Slot = CMap[Pair];
if (!Slot || Slot == GV)
continue;
if (!Slot->hasUnnamedAddr() && !GV->hasUnnamedAddr())
continue;
if (!GV->hasUnnamedAddr())
Slot->setUnnamedAddr(false);
// Make all uses of the duplicate constant use the canonical version.
Replacements.push_back(std::make_pair(GV, Slot));
}
if (Replacements.empty())
return MadeChange;
CMap.clear();
// Now that we have figured out which replacements must be made, do them all
// now. This avoid invalidating the pointers in CMap, which are unneeded
// now.
for (unsigned i = 0, e = Replacements.size(); i != e; ++i) {
// Bump the alignment if necessary.
if (Replacements[i].first->getAlignment() ||
Replacements[i].second->getAlignment()) {
Replacements[i].second->setAlignment(std::max(
Replacements[i].first->getAlignment(),
Replacements[i].second->getAlignment()));
}
// Eliminate any uses of the dead global.
Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
// Delete the global value from the module.
assert(Replacements[i].first->hasLocalLinkage() &&
"Refusing to delete an externally visible global variable.");
Replacements[i].first->eraseFromParent();
}
NumMerged += Replacements.size();
Replacements.clear();
}
}
bool ConstantMerge::runOnModule(Module &M) {
// Find all the globals that are marked "used". These cannot be merged.
SmallPtrSet<const GlobalValue*, 8> UsedGlobals;
FindUsedValues(M.getGlobalVariable("llvm.used"), UsedGlobals);
FindUsedValues(M.getGlobalVariable("llvm.compiler.used"), UsedGlobals);
// Map unique constant/section pairs to globals. We don't want to merge
// globals in different sections.
DenseMap<Constant*, GlobalVariable*> CMap;
// Replacements - This vector contains a list of replacements to perform.
SmallVector<std::pair<GlobalVariable*, GlobalVariable*>, 32> Replacements;
bool MadeChange = false;
// Iterate constant merging while we are still making progress. Merging two
// constants together may allow us to merge other constants together if the
// second level constants have initializers which point to the globals that
// were just merged.
while (1) {
// First pass: identify all globals that can be merged together, filling in
// the Replacements vector. We cannot do the replacement in this pass
// because doing so may cause initializers of other globals to be rewritten,
// invalidating the Constant* pointers in CMap.
//
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
// If this GV is dead, remove it.
GV->removeDeadConstantUsers();
if (GV->use_empty() && GV->hasLocalLinkage()) {
GV->eraseFromParent();
continue;
}
// Only process constants with initializers in the default addres space.
if (!GV->isConstant() ||!GV->hasDefinitiveInitializer() ||
GV->getType()->getAddressSpace() != 0 || !GV->getSection().empty() ||
// Don't touch values marked with attribute(used).
UsedGlobals.count(GV))
continue;
Constant *Init = GV->getInitializer();
// Check to see if the initializer is already known.
GlobalVariable *&Slot = CMap[Init];
if (Slot == 0) { // Nope, add it to the map.
Slot = GV;
} else if (GV->hasLocalLinkage()) { // Yup, this is a duplicate!
// Make all uses of the duplicate constant use the canonical version.
Replacements.push_back(std::make_pair(GV, Slot));
}
}
if (Replacements.empty())
return MadeChange;
CMap.clear();
// Now that we have figured out which replacements must be made, do them all
// now. This avoid invalidating the pointers in CMap, which are unneeded
// now.
for (unsigned i = 0, e = Replacements.size(); i != e; ++i) {
// Eliminate any uses of the dead global.
Replacements[i].first->replaceAllUsesWith(Replacements[i].second);
// Delete the global value from the module.
Replacements[i].first->eraseFromParent();
}
NumMerged += Replacements.size();
Replacements.clear();
}
}