bool GlobalMerge::doInitialization(Module &M) {
DenseMap<unsigned, SmallVector<GlobalVariable*, 16> > Globals, ConstGlobals,
BSSGlobals;
const DataLayout *TD = TLI->getDataLayout();
unsigned MaxOffset = TLI->getMaximalGlobalOffset();
bool Changed = false;
// Grab all non-const globals.
for (Module::global_iterator I = M.global_begin(),
E = M.global_end(); I != E; ++I) {
// Merge is safe for "normal" internal globals only
if (!I->hasLocalLinkage() || I->isThreadLocal() || I->hasSection())
continue;
PointerType *PT = dyn_cast<PointerType>(I->getType());
assert(PT && "Global variable is not a pointer!");
unsigned AddressSpace = PT->getAddressSpace();
// Ignore fancy-aligned globals for now.
unsigned Alignment = TD->getPreferredAlignment(I);
Type *Ty = I->getType()->getElementType();
if (Alignment > TD->getABITypeAlignment(Ty))
continue;
// Ignore all 'special' globals.
if (I->getName().startswith("llvm.") ||
I->getName().startswith(".llvm."))
continue;
if (TD->getTypeAllocSize(Ty) < MaxOffset) {
if (TargetLoweringObjectFile::getKindForGlobal(I, TLI->getTargetMachine())
.isBSSLocal())
BSSGlobals[AddressSpace].push_back(I);
else if (I->isConstant())
ConstGlobals[AddressSpace].push_back(I);
else
Globals[AddressSpace].push_back(I);
}
}
for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
I = Globals.begin(), E = Globals.end(); I != E; ++I)
if (I->second.size() > 1)
Changed |= doMerge(I->second, M, false, I->first);
for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
I = BSSGlobals.begin(), E = BSSGlobals.end(); I != E; ++I)
if (I->second.size() > 1)
Changed |= doMerge(I->second, M, false, I->first);
// FIXME: This currently breaks the EH processing due to way how the
// typeinfo detection works. We might want to detect the TIs and ignore
// them in the future.
// if (ConstGlobals.size() > 1)
// Changed |= doMerge(ConstGlobals, M, true);
return Changed;
}
bool ARMGlobalMerge::doInitialization(Module &M) {
SmallVector<GlobalVariable*, 16> Globals, ConstGlobals, BSSGlobals;
const TargetData *TD = TLI->getTargetData();
unsigned MaxOffset = TLI->getMaximalGlobalOffset();
bool Changed = false;
// Disable this pass on darwin. The debugger is not yet ready to extract
// variable's info from a merged global.
if (TLI->getTargetMachine().getSubtarget<ARMSubtarget>().isTargetDarwin())
return false;
// Grab all non-const globals.
for (Module::global_iterator I = M.global_begin(),
E = M.global_end(); I != E; ++I) {
// Merge is safe for "normal" internal globals only
if (!I->hasLocalLinkage() || I->isThreadLocal() || I->hasSection())
continue;
// Ignore fancy-aligned globals for now.
if (I->getAlignment() != 0)
continue;
// Ignore all 'special' globals.
if (I->getName().startswith("llvm.") ||
I->getName().startswith(".llvm."))
continue;
if (TD->getTypeAllocSize(I->getType()->getElementType()) < MaxOffset) {
const TargetLoweringObjectFile &TLOF = TLI->getObjFileLowering();
if (TLOF.getKindForGlobal(I, TLI->getTargetMachine()).isBSSLocal())
BSSGlobals.push_back(I);
else if (I->isConstant())
ConstGlobals.push_back(I);
else
Globals.push_back(I);
}
}
if (Globals.size() > 1)
Changed |= doMerge(Globals, M, false);
if (BSSGlobals.size() > 1)
Changed |= doMerge(BSSGlobals, M, false);
// FIXME: This currently breaks the EH processing due to way how the
// typeinfo detection works. We might want to detect the TIs and ignore
// them in the future.
// if (ConstGlobals.size() > 1)
// Changed |= doMerge(ConstGlobals, M, true);
return Changed;
}
bool ARMGlobalMerge::doInitialization(Module &M) {
SmallVector<GlobalVariable*, 16> Globals, ConstGlobals;
const TargetData *TD = TLI->getTargetData();
unsigned MaxOffset = TLI->getMaximalGlobalOffset();
bool Changed = false;
// Grab all non-const globals.
for (Module::global_iterator I = M.global_begin(),
E = M.global_end(); I != E; ++I) {
// Merge is safe for "normal" internal globals only
if (!I->hasLocalLinkage() || I->isThreadLocal() || I->hasSection())
continue;
// Ignore fancy-aligned globals for now.
if (I->getAlignment() != 0)
continue;
// Ignore all 'special' globals.
if (I->getName().startswith("llvm.") ||
I->getName().startswith(".llvm."))
continue;
if (TD->getTypeAllocSize(I->getType()) < MaxOffset) {
if (I->isConstant())
ConstGlobals.push_back(I);
else
Globals.push_back(I);
}
}
if (Globals.size() > 1)
Changed |= doMerge(Globals, M, false);
// FIXME: This currently breaks the EH processing due to way how the
// typeinfo detection works. We might want to detect the TIs and ignore
// them in the future.
// if (ConstGlobals.size() > 1)
// Changed |= doMerge(ConstGlobals, M, true);
return Changed;
}
bool GlobalMerge::doInitialization(Module &M) {
if (!EnableGlobalMerge)
return false;
auto &DL = M.getDataLayout();
DenseMap<unsigned, SmallVector<GlobalVariable*, 16> > Globals, ConstGlobals,
BSSGlobals;
bool Changed = false;
setMustKeepGlobalVariables(M);
// Grab all non-const globals.
for (Module::global_iterator I = M.global_begin(),
E = M.global_end(); I != E; ++I) {
// Merge is safe for "normal" internal or external globals only
if (I->isDeclaration() || I->isThreadLocal() || I->hasSection())
continue;
if (!(EnableGlobalMergeOnExternal && I->hasExternalLinkage()) &&
!I->hasInternalLinkage())
continue;
PointerType *PT = dyn_cast<PointerType>(I->getType());
assert(PT && "Global variable is not a pointer!");
unsigned AddressSpace = PT->getAddressSpace();
// Ignore fancy-aligned globals for now.
unsigned Alignment = DL.getPreferredAlignment(I);
Type *Ty = I->getType()->getElementType();
if (Alignment > DL.getABITypeAlignment(Ty))
continue;
// Ignore all 'special' globals.
if (I->getName().startswith("llvm.") ||
I->getName().startswith(".llvm."))
continue;
// Ignore all "required" globals:
if (isMustKeepGlobalVariable(I))
continue;
if (DL.getTypeAllocSize(Ty) < MaxOffset) {
if (TargetLoweringObjectFile::getKindForGlobal(I, *TM).isBSSLocal())
BSSGlobals[AddressSpace].push_back(I);
else if (I->isConstant())
ConstGlobals[AddressSpace].push_back(I);
else
Globals[AddressSpace].push_back(I);
}
}
for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
I = Globals.begin(), E = Globals.end(); I != E; ++I)
if (I->second.size() > 1)
Changed |= doMerge(I->second, M, false, I->first);
for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
I = BSSGlobals.begin(), E = BSSGlobals.end(); I != E; ++I)
if (I->second.size() > 1)
Changed |= doMerge(I->second, M, false, I->first);
if (EnableGlobalMergeOnConst)
for (DenseMap<unsigned, SmallVector<GlobalVariable*, 16> >::iterator
I = ConstGlobals.begin(), E = ConstGlobals.end(); I != E; ++I)
if (I->second.size() > 1)
Changed |= doMerge(I->second, M, true, I->first);
return Changed;
}
static PointerType *buildTlsTemplate(Module &M, std::vector<VarInfo> *TlsVars) {
std::vector<Type*> FieldBssTypes;
std::vector<Type*> FieldInitTypes;
std::vector<Constant*> FieldInitValues;
PassState State(&M);
for (Module::global_iterator GV = M.global_begin();
GV != M.global_end();
++GV) {
if (GV->isThreadLocal()) {
if (!GV->hasInitializer()) {
// Since this is a whole-program transformation, "extern" TLS
// variables are not allowed at this point.
report_fatal_error(std::string("TLS variable without an initializer: ")
+ GV->getName());
}
if (!GV->getInitializer()->isNullValue()) {
addVarToTlsTemplate(&State, &FieldInitTypes,
&FieldInitValues, GV);
VarInfo Info;
Info.TlsVar = GV;
Info.IsBss = false;
Info.TemplateIndex = FieldInitTypes.size() - 1;
TlsVars->push_back(Info);
}
}
}
// Handle zero-initialized TLS variables in a second pass, because
// these should follow non-zero-initialized TLS variables.
for (Module::global_iterator GV = M.global_begin();
GV != M.global_end();
++GV) {
if (GV->isThreadLocal() && GV->getInitializer()->isNullValue()) {
addVarToTlsTemplate(&State, &FieldBssTypes, NULL, GV);
VarInfo Info;
Info.TlsVar = GV;
Info.IsBss = true;
Info.TemplateIndex = FieldBssTypes.size() - 1;
TlsVars->push_back(Info);
}
}
// Add final alignment padding so that
// (struct tls_struct *) __nacl_read_tp() - 1
// gives the correct, aligned start of the TLS variables given the
// x86-style layout we are using. This requires some more bytes to
// be memset() to zero at runtime. This wastage doesn't seem
// important gives that we're not trying to optimize packing by
// reordering to put similarly-aligned variables together.
padToAlignment(&State, &FieldBssTypes, NULL, State.Alignment);
// We create the TLS template structs as "packed" because we insert
// alignment padding ourselves, and LLVM's implicit insertion of
// padding would interfere with ours. tls_bss_template can start at
// a non-aligned address immediately following the last field in
// tls_init_template.
StructType *InitTemplateType =
StructType::create(M.getContext(), "tls_init_template");
InitTemplateType->setBody(FieldInitTypes, /*isPacked=*/true);
StructType *BssTemplateType =
StructType::create(M.getContext(), "tls_bss_template");
BssTemplateType->setBody(FieldBssTypes, /*isPacked=*/true);
StructType *TemplateType = StructType::create(M.getContext(), "tls_struct");
SmallVector<Type*, 2> TemplateTopFields;
TemplateTopFields.push_back(InitTemplateType);
TemplateTopFields.push_back(BssTemplateType);
TemplateType->setBody(TemplateTopFields, /*isPacked=*/true);
PointerType *TemplatePtrType = PointerType::get(TemplateType, 0);
// We define the following symbols, which are the same as those
// defined by NaCl's original customized binutils linker scripts:
// __tls_template_start
// __tls_template_tdata_end
// __tls_template_end
// We also define __tls_template_alignment, which was not defined by
// the original linker scripts.
const char *StartSymbol = "__tls_template_start";
Constant *TemplateData = ConstantStruct::get(InitTemplateType,
FieldInitValues);
GlobalVariable *TemplateDataVar =
new GlobalVariable(M, InitTemplateType, /*isConstant=*/true,
GlobalValue::InternalLinkage, TemplateData);
setGlobalVariableValue(M, StartSymbol, TemplateDataVar);
TemplateDataVar->setName(StartSymbol);
Constant *TdataEnd = ConstantExpr::getGetElementPtr(
TemplateDataVar,
ConstantInt::get(M.getContext(), APInt(32, 1)));
setGlobalVariableValue(M, "__tls_template_tdata_end", TdataEnd);
Constant *TotalEnd = ConstantExpr::getGetElementPtr(
ConstantExpr::getBitCast(TemplateDataVar, TemplatePtrType),
ConstantInt::get(M.getContext(), APInt(32, 1)));
setGlobalVariableValue(M, "__tls_template_end", TotalEnd);
const char *AlignmentSymbol = "__tls_template_alignment";
Type *i32 = Type::getInt32Ty(M.getContext());
GlobalVariable *AlignmentVar = new GlobalVariable(
M, i32, /*isConstant=*/true,
GlobalValue::InternalLinkage,
ConstantInt::get(M.getContext(), APInt(32, State.Alignment)));
setGlobalVariableValue(M, AlignmentSymbol, AlignmentVar);
AlignmentVar->setName(AlignmentSymbol);
return TemplatePtrType;
}