Implement target independent TLS compatible with glibc's emutls.c.
The 'common' section TLS is not implemented.
Current C/C++ TLS variables are not placed in common section.
DWARF debug info to get the address of TLS variables is not generated yet.
clang and driver changes in http://reviews.llvm.org/D10524
Added -femulated-tls flag to select the emulated TLS model,
which will be used for old targets like Android that do not
support ELF TLS models.
Added TargetLowering::LowerToTLSEmulatedModel as a target-independent
function to convert a SDNode of TLS variable address to a function call
to __emutls_get_address.
Added into lib/Target/*/*ISelLowering.cpp to call LowerToTLSEmulatedModel
for TLSModel::Emulated. Although all targets supporting ELF TLS models are
enhanced, emulated TLS model has been tested only for Android ELF targets.
Modified AsmPrinter.cpp to print the emutls_v.* and emutls_t.* variables for
emulated TLS variables.
Modified DwarfCompileUnit.cpp to skip some DIE for emulated TLS variabls.
TODO: Add proper DIE for emulated TLS variables.
Added new unit tests with emulated TLS.
Differential Revision: http://reviews.llvm.org/D10522
llvm-svn: 243438
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 8a08546..bf1b628 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -343,8 +343,58 @@
return TM.getSymbol(GV, *Mang);
}
+static MCSymbol *getOrCreateEmuTLSControlSym(MCSymbol *GVSym, MCContext &C) {
+ return C.getOrCreateSymbol(Twine("__emutls_v.") + GVSym->getName());
+}
+
+static MCSymbol *getOrCreateEmuTLSInitSym(MCSymbol *GVSym, MCContext &C) {
+ return C.getOrCreateSymbol(Twine("__emutls_t.") + GVSym->getName());
+}
+
+/// EmitEmulatedTLSControlVariable - Emit the control variable for an emulated TLS variable.
+void AsmPrinter::EmitEmulatedTLSControlVariable(const GlobalVariable *GV,
+ MCSymbol *EmittedSym,
+ bool AllZeroInitValue) {
+ // If there is init value, use .data.rel.local section;
+ // otherwise use the .data section.
+ MCSection *TLSVarSection = const_cast<MCSection*>(
+ (GV->hasInitializer() && !AllZeroInitValue)
+ ? getObjFileLowering().getDataRelLocalSection()
+ : getObjFileLowering().getDataSection());
+ OutStreamer->SwitchSection(TLSVarSection);
+ MCSymbol *GVSym = getSymbol(GV);
+ EmitLinkage(GV, EmittedSym); // same linkage as GV
+ const DataLayout &DL = GV->getParent()->getDataLayout();
+ uint64_t Size = DL.getTypeAllocSize(GV->getType()->getElementType());
+ unsigned AlignLog = getGVAlignmentLog2(GV, DL);
+ unsigned WordSize = DL.getPointerSize();
+ unsigned Alignment = DL.getPointerABIAlignment();
+ EmitAlignment(Log2_32(Alignment));
+ OutStreamer->EmitLabel(EmittedSym);
+ OutStreamer->EmitIntValue(Size, WordSize);
+ OutStreamer->EmitIntValue((1 << AlignLog), WordSize);
+ OutStreamer->EmitIntValue(0, WordSize);
+ if (GV->hasInitializer() && !AllZeroInitValue) {
+ OutStreamer->EmitSymbolValue(
+ getOrCreateEmuTLSInitSym(GVSym, OutContext), WordSize);
+ } else
+ OutStreamer->EmitIntValue(0, WordSize);
+ if (MAI->hasDotTypeDotSizeDirective())
+ OutStreamer->emitELFSize(cast<MCSymbolELF>(EmittedSym),
+ MCConstantExpr::create(4 * WordSize, OutContext));
+ OutStreamer->AddBlankLine(); // End of the __emutls_v.* variable.
+}
+
/// EmitGlobalVariable - Emit the specified global variable to the .s file.
void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
+ bool IsEmuTLSVar =
+ GV->getThreadLocalMode() != llvm::GlobalVariable::NotThreadLocal &&
+ TM.Options.EmulatedTLS;
+ assert((!IsEmuTLSVar || getObjFileLowering().getDataRelLocalSection()) &&
+ "Need relocatable local section for emulated TLS variables");
+ assert(!(IsEmuTLSVar && GV->hasCommonLinkage()) &&
+ "No emulated TLS variables in the common section");
+
if (GV->hasInitializer()) {
// Check to see if this is a special global used by LLVM, if so, emit it.
if (EmitSpecialLLVMGlobal(GV))
@@ -355,7 +405,9 @@
if (GlobalGOTEquivs.count(getSymbol(GV)))
return;
- if (isVerbose()) {
+ if (isVerbose() && !IsEmuTLSVar) {
+ // When printing the control variable __emutls_v.*,
+ // we don't need to print the original TLS variable name.
GV->printAsOperand(OutStreamer->GetCommentOS(),
/*PrintType=*/false, GV->getParent());
OutStreamer->GetCommentOS() << '\n';
@@ -363,7 +415,12 @@
}
MCSymbol *GVSym = getSymbol(GV);
- EmitVisibility(GVSym, GV->getVisibility(), !GV->isDeclaration());
+ MCSymbol *EmittedSym = IsEmuTLSVar ?
+ getOrCreateEmuTLSControlSym(GVSym, OutContext) : GVSym;
+ // getOrCreateEmuTLSControlSym only creates the symbol with name and default attributes.
+ // GV's or GVSym's attributes will be used for the EmittedSym.
+
+ EmitVisibility(EmittedSym, GV->getVisibility(), !GV->isDeclaration());
if (!GV->hasInitializer()) // External globals require no extra code.
return;
@@ -374,7 +431,7 @@
"' is already defined");
if (MAI->hasDotTypeDotSizeDirective())
- OutStreamer->EmitSymbolAttribute(GVSym, MCSA_ELF_TypeObject);
+ OutStreamer->EmitSymbolAttribute(EmittedSym, MCSA_ELF_TypeObject);
SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
@@ -386,6 +443,18 @@
// sections and expected to be contiguous (e.g. ObjC metadata).
unsigned AlignLog = getGVAlignmentLog2(GV, DL);
+ bool AllZeroInitValue = false;
+ const Constant *InitValue = GV->getInitializer();
+ if (isa<ConstantAggregateZero>(InitValue))
+ AllZeroInitValue = true;
+ else {
+ const ConstantInt *InitIntValue = dyn_cast<ConstantInt>(InitValue);
+ if (InitIntValue && InitIntValue->isZero())
+ AllZeroInitValue = true;
+ }
+ if (IsEmuTLSVar)
+ EmitEmulatedTLSControlVariable(GV, EmittedSym, AllZeroInitValue);
+
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerGroupName, TimePassesIsEnabled);
HI.Handler->setSymbolSize(GVSym, Size);
@@ -393,6 +462,8 @@
// Handle common and BSS local symbols (.lcomm).
if (GVKind.isCommon() || GVKind.isBSSLocal()) {
+ assert(!(IsEmuTLSVar && GVKind.isCommon()) &&
+ "No emulated TLS variables in the common section");
if (Size == 0) Size = 1; // .comm Foo, 0 is undefined, avoid it.
unsigned Align = 1 << AlignLog;
@@ -437,12 +508,21 @@
return;
}
- MCSection *TheSection =
+ if (IsEmuTLSVar && AllZeroInitValue)
+ return; // No need of initialization values.
+
+ MCSymbol *EmittedInitSym = IsEmuTLSVar ?
+ getOrCreateEmuTLSInitSym(GVSym, OutContext) : GVSym;
+ // getOrCreateEmuTLSInitSym only creates the symbol with name and default attributes.
+ // GV's or GVSym's attributes will be used for the EmittedInitSym.
+
+ MCSection *TheSection = IsEmuTLSVar ?
+ getObjFileLowering().getReadOnlySection() :
getObjFileLowering().SectionForGlobal(GV, GVKind, *Mang, TM);
// Handle the zerofill directive on darwin, which is a special form of BSS
// emission.
- if (GVKind.isBSSExtern() && MAI->hasMachoZeroFillDirective()) {
+ if (GVKind.isBSSExtern() && MAI->hasMachoZeroFillDirective() && !IsEmuTLSVar) {
if (Size == 0) Size = 1; // zerofill of 0 bytes is undefined.
// .globl _foo
@@ -462,7 +542,7 @@
// TLOF class. This will also make it more obvious that stuff like
// MCStreamer::EmitTBSSSymbol is macho specific and only called from macho
// specific code.
- if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective()) {
+ if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective() && !IsEmuTLSVar) {
// Emit the .tbss symbol
MCSymbol *MangSym =
OutContext.getOrCreateSymbol(GVSym->getName() + Twine("$tlv$init"));
@@ -506,16 +586,18 @@
OutStreamer->SwitchSection(TheSection);
- EmitLinkage(GV, GVSym);
+ // emutls_t.* symbols are only used in the current compilation unit.
+ if (!IsEmuTLSVar)
+ EmitLinkage(GV, EmittedInitSym);
EmitAlignment(AlignLog, GV);
- OutStreamer->EmitLabel(GVSym);
+ OutStreamer->EmitLabel(EmittedInitSym);
EmitGlobalConstant(GV->getParent()->getDataLayout(), GV->getInitializer());
if (MAI->hasDotTypeDotSizeDirective())
// .size foo, 42
- OutStreamer->emitELFSize(cast<MCSymbolELF>(GVSym),
+ OutStreamer->emitELFSize(cast<MCSymbolELF>(EmittedInitSym),
MCConstantExpr::create(Size, OutContext));
OutStreamer->AddBlankLine();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index fc54a29..f29ad65 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -151,28 +151,32 @@
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
const MCSymbol *Sym = Asm->getSymbol(Global);
if (Global->isThreadLocal()) {
- // FIXME: Make this work with -gsplit-dwarf.
- unsigned PointerSize = Asm->getDataLayout().getPointerSize();
- assert((PointerSize == 4 || PointerSize == 8) &&
- "Add support for other sizes if necessary");
- // Based on GCC's support for TLS:
- if (!DD->useSplitDwarf()) {
- // 1) Start with a constNu of the appropriate pointer size
- addUInt(*Loc, dwarf::DW_FORM_data1,
- PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
- // 2) containing the (relocated) offset of the TLS variable
- // within the module's TLS block.
- addExpr(*Loc, dwarf::DW_FORM_udata,
- Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
+ if (Asm->TM.Options.EmulatedTLS) {
+ // TODO: add debug info for emulated thread local mode.
} else {
- addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
- addUInt(*Loc, dwarf::DW_FORM_udata,
- DD->getAddressPool().getIndex(Sym, /* TLS */ true));
+ // FIXME: Make this work with -gsplit-dwarf.
+ unsigned PointerSize = Asm->getDataLayout().getPointerSize();
+ assert((PointerSize == 4 || PointerSize == 8) &&
+ "Add support for other sizes if necessary");
+ // Based on GCC's support for TLS:
+ if (!DD->useSplitDwarf()) {
+ // 1) Start with a constNu of the appropriate pointer size
+ addUInt(*Loc, dwarf::DW_FORM_data1,
+ PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
+ // 2) containing the (relocated) offset of the TLS variable
+ // within the module's TLS block.
+ addExpr(*Loc, dwarf::DW_FORM_udata,
+ Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
+ } else {
+ addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
+ addUInt(*Loc, dwarf::DW_FORM_udata,
+ DD->getAddressPool().getIndex(Sym, /* TLS */ true));
+ }
+ // 3) followed by an OP to make the debugger do a TLS lookup.
+ addUInt(*Loc, dwarf::DW_FORM_data1,
+ DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
+ : dwarf::DW_OP_form_tls_address);
}
- // 3) followed by an OP to make the debugger do a TLS lookup.
- addUInt(*Loc, dwarf::DW_FORM_data1,
- DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
- : dwarf::DW_OP_form_tls_address);
} else {
DD->addArangeLabel(SymbolCU(this, Sym));
addOpAddress(*Loc, Sym);
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index bacf8be..ffffaf0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3044,3 +3044,46 @@
DAG.getConstant(0, dl, NVT), Ret, ISD::SETLT);
return true;
}
+
+//===----------------------------------------------------------------------===//
+// Implementation of Emulated TLS Model
+//===----------------------------------------------------------------------===//
+
+SDValue TargetLowering::LowerToTLSEmulatedModel(const GlobalAddressSDNode *GA,
+ SelectionDAG &DAG) const {
+ // Access to address of TLS varialbe xyz is lowered to a function call:
+ // __emutls_get_address( address of global variable named "__emutls_v.xyz" )
+ EVT PtrVT = getPointerTy(DAG.getDataLayout());
+ PointerType *VoidPtrType = Type::getInt8PtrTy(*DAG.getContext());
+ SDLoc dl(GA);
+
+ ArgListTy Args;
+ ArgListEntry Entry;
+ std::string NameString = ("__emutls_v." + GA->getGlobal()->getName()).str();
+ Module *VariableModule = const_cast<Module*>(GA->getGlobal()->getParent());
+ StringRef EmuTlsVarName(NameString);
+ GlobalVariable *EmuTlsVar = VariableModule->getNamedGlobal(EmuTlsVarName);
+ if (!EmuTlsVar)
+ EmuTlsVar = dyn_cast_or_null<GlobalVariable>(
+ VariableModule->getOrInsertGlobal(EmuTlsVarName, VoidPtrType));
+ Entry.Node = DAG.getGlobalAddress(EmuTlsVar, dl, PtrVT);
+ Entry.Ty = VoidPtrType;
+ Args.push_back(Entry);
+
+ SDValue EmuTlsGetAddr = DAG.getExternalSymbol("__emutls_get_address", PtrVT);
+
+ TargetLowering::CallLoweringInfo CLI(DAG);
+ CLI.setDebugLoc(dl).setChain(DAG.getEntryNode());
+ CLI.setCallee(CallingConv::C, VoidPtrType, EmuTlsGetAddr, std::move(Args), 0);
+ std::pair<SDValue, SDValue> CallResult = LowerCallTo(CLI);
+
+ // TLSADDR will be codegen'ed as call. Inform MFI that function has calls.
+ // At last for X86 targets, maybe good for other targets too?
+ MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
+ MFI->setAdjustsStack(true); // Is this only for X86 target?
+ MFI->setHasCalls(true);
+
+ assert((GA->getOffset() == 0) &&
+ "Emulated TLS must have zero offset in GlobalAddressSDNode");
+ return CallResult.first;
+}