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//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with code generation of C++ declarations
//
//===----------------------------------------------------------------------===//
#include "CGCXXABI.h"
#include "CGObjCRuntime.h"
#include "CGOpenMPRuntime.h"
#include "CodeGenFunction.h"
#include "TargetInfo.h"
#include "clang/AST/Attr.h"
#include "clang/Basic/LangOptions.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/Path.h"
using namespace clang;
using namespace CodeGen;
static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
ConstantAddress DeclPtr) {
assert(
(D.hasGlobalStorage() ||
(D.hasLocalStorage() && CGF.getContext().getLangOpts().OpenCLCPlusPlus)) &&
"VarDecl must have global or local (in the case of OpenCL) storage!");
assert(!D.getType()->isReferenceType() &&
"Should not call EmitDeclInit on a reference!");
QualType type = D.getType();
LValue lv = CGF.MakeAddrLValue(DeclPtr, type);
const Expr *Init = D.getInit();
switch (CGF.getEvaluationKind(type)) {
case TEK_Scalar: {
CodeGenModule &CGM = CGF.CGM;
if (lv.isObjCStrong())
CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
DeclPtr, D.getTLSKind());
else if (lv.isObjCWeak())
CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
DeclPtr);
else
CGF.EmitScalarInit(Init, &D, lv, false);
return;
}
case TEK_Complex:
CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true);
return;
case TEK_Aggregate:
CGF.EmitAggExpr(Init,
AggValueSlot::forLValue(lv, CGF, AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
AggValueSlot::DoesNotOverlap));
return;
}
llvm_unreachable("bad evaluation kind");
}
/// Emit code to cause the destruction of the given variable with
/// static storage duration.
static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
ConstantAddress Addr) {
// Honor __attribute__((no_destroy)) and bail instead of attempting
// to emit a reference to a possibly nonexistent destructor, which
// in turn can cause a crash. This will result in a global constructor
// that isn't balanced out by a destructor call as intended by the
// attribute. This also checks for -fno-c++-static-destructors and
// bails even if the attribute is not present.
QualType::DestructionKind DtorKind = D.needsDestruction(CGF.getContext());
// FIXME: __attribute__((cleanup)) ?
switch (DtorKind) {
case QualType::DK_none:
return;
case QualType::DK_cxx_destructor:
break;
case QualType::DK_objc_strong_lifetime:
case QualType::DK_objc_weak_lifetime:
case QualType::DK_nontrivial_c_struct:
// We don't care about releasing objects during process teardown.
assert(!D.getTLSKind() && "should have rejected this");
return;
}
llvm::FunctionCallee Func;
llvm::Constant *Argument;
CodeGenModule &CGM = CGF.CGM;
QualType Type = D.getType();
// Special-case non-array C++ destructors, if they have the right signature.
// Under some ABIs, destructors return this instead of void, and cannot be
// passed directly to __cxa_atexit if the target does not allow this
// mismatch.
const CXXRecordDecl *Record = Type->getAsCXXRecordDecl();
bool CanRegisterDestructor =
Record && (!CGM.getCXXABI().HasThisReturn(
GlobalDecl(Record->getDestructor(), Dtor_Complete)) ||
CGM.getCXXABI().canCallMismatchedFunctionType());
// If __cxa_atexit is disabled via a flag, a different helper function is
// generated elsewhere which uses atexit instead, and it takes the destructor
// directly.
bool UsingExternalHelper = !CGM.getCodeGenOpts().CXAAtExit;
if (Record && (CanRegisterDestructor || UsingExternalHelper)) {
assert(!Record->hasTrivialDestructor());
CXXDestructorDecl *Dtor = Record->getDestructor();
Func = CGM.getAddrAndTypeOfCXXStructor(GlobalDecl(Dtor, Dtor_Complete));
if (CGF.getContext().getLangOpts().OpenCL) {
auto DestAS =
CGM.getTargetCodeGenInfo().getAddrSpaceOfCxaAtexitPtrParam();
auto DestTy = CGF.getTypes().ConvertType(Type)->getPointerTo(
CGM.getContext().getTargetAddressSpace(DestAS));
auto SrcAS = D.getType().getQualifiers().getAddressSpace();
if (DestAS == SrcAS)
Argument = llvm::ConstantExpr::getBitCast(Addr.getPointer(), DestTy);
else
// FIXME: On addr space mismatch we are passing NULL. The generation
// of the global destructor function should be adjusted accordingly.
Argument = llvm::ConstantPointerNull::get(DestTy);
} else {
Argument = llvm::ConstantExpr::getBitCast(
Addr.getPointer(), CGF.getTypes().ConvertType(Type)->getPointerTo());
}
// Otherwise, the standard logic requires a helper function.
} else {
Addr = Addr.getElementBitCast(CGF.ConvertTypeForMem(Type));
Func = CodeGenFunction(CGM)
.generateDestroyHelper(Addr, Type, CGF.getDestroyer(DtorKind),
CGF.needsEHCleanup(DtorKind), &D);
Argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
}
CGM.getCXXABI().registerGlobalDtor(CGF, D, Func, Argument);
}
/// Emit code to cause the variable at the given address to be considered as
/// constant from this point onwards.
static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
llvm::Constant *Addr) {
return CGF.EmitInvariantStart(
Addr, CGF.getContext().getTypeSizeInChars(D.getType()));
}
void CodeGenFunction::EmitInvariantStart(llvm::Constant *Addr, CharUnits Size) {
// Do not emit the intrinsic if we're not optimizing.
if (!CGM.getCodeGenOpts().OptimizationLevel)
return;
// Grab the llvm.invariant.start intrinsic.
llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
// Overloaded address space type.
llvm::Type *ObjectPtr[1] = {Int8PtrTy};
llvm::Function *InvariantStart = CGM.getIntrinsic(InvStartID, ObjectPtr);
// Emit a call with the size in bytes of the object.
uint64_t Width = Size.getQuantity();
llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(Int64Ty, Width),
llvm::ConstantExpr::getBitCast(Addr, Int8PtrTy)};
Builder.CreateCall(InvariantStart, Args);
}
void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
llvm::GlobalVariable *GV,
bool PerformInit) {
const Expr *Init = D.getInit();
QualType T = D.getType();
// The address space of a static local variable (DeclPtr) may be different
// from the address space of the "this" argument of the constructor. In that
// case, we need an addrspacecast before calling the constructor.
//
// struct StructWithCtor {
// __device__ StructWithCtor() {...}
// };
// __device__ void foo() {
// __shared__ StructWithCtor s;
// ...
// }
//
// For example, in the above CUDA code, the static local variable s has a
// "shared" address space qualifier, but the constructor of StructWithCtor
// expects "this" in the "generic" address space.
unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T);
unsigned ActualAddrSpace = GV->getAddressSpace();
llvm::Constant *DeclPtr = GV;
if (ActualAddrSpace != ExpectedAddrSpace) {
llvm::PointerType *PTy = llvm::PointerType::getWithSamePointeeType(
GV->getType(), ExpectedAddrSpace);
DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
}
ConstantAddress DeclAddr(
DeclPtr, GV->getValueType(), getContext().getDeclAlign(&D));
if (!T->isReferenceType()) {
if (getLangOpts().OpenMP && !getLangOpts().OpenMPSimd &&
D.hasAttr<OMPThreadPrivateDeclAttr>()) {
(void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
&D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
PerformInit, this);
}
if (PerformInit)
EmitDeclInit(*this, D, DeclAddr);
if (CGM.isTypeConstant(D.getType(), true))
EmitDeclInvariant(*this, D, DeclPtr);
else
EmitDeclDestroy(*this, D, DeclAddr);
return;
}
assert(PerformInit && "cannot have constant initializer which needs "
"destruction for reference");
RValue RV = EmitReferenceBindingToExpr(Init);
EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T);
}
/// Create a stub function, suitable for being passed to atexit,
/// which passes the given address to the given destructor function.
llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD,
llvm::FunctionCallee dtor,
llvm::Constant *addr) {
// Get the destructor function type, void(*)(void).
llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
SmallString<256> FnName;
{
llvm::raw_svector_ostream Out(FnName);
CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
}
const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
ty, FnName.str(), FI, VD.getLocation());
CodeGenFunction CGF(CGM);
CGF.StartFunction(GlobalDecl(&VD, DynamicInitKind::AtExit),
CGM.getContext().VoidTy, fn, FI, FunctionArgList(),
VD.getLocation(), VD.getInit()->getExprLoc());
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(CGF);
llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
// Make sure the call and the callee agree on calling convention.
if (auto *dtorFn = dyn_cast<llvm::Function>(
dtor.getCallee()->stripPointerCastsAndAliases()))
call->setCallingConv(dtorFn->getCallingConv());
CGF.FinishFunction();
return fn;
}
/// Create a stub function, suitable for being passed to __pt_atexit_np,
/// which passes the given address to the given destructor function.
llvm::Function *CodeGenFunction::createTLSAtExitStub(
const VarDecl &D, llvm::FunctionCallee Dtor, llvm::Constant *Addr,
llvm::FunctionCallee &AtExit) {
SmallString<256> FnName;
{
llvm::raw_svector_ostream Out(FnName);
CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&D, Out);
}
const CGFunctionInfo &FI = CGM.getTypes().arrangeLLVMFunctionInfo(
getContext().IntTy, /*instanceMethod=*/false, /*chainCall=*/false,
{getContext().IntTy}, FunctionType::ExtInfo(), {}, RequiredArgs::All);
// Get the stub function type, int(*)(int,...).
llvm::FunctionType *StubTy =
llvm::FunctionType::get(CGM.IntTy, {CGM.IntTy}, true);
llvm::Function *DtorStub = CGM.CreateGlobalInitOrCleanUpFunction(
StubTy, FnName.str(), FI, D.getLocation());
CodeGenFunction CGF(CGM);
FunctionArgList Args;
ImplicitParamDecl IPD(CGM.getContext(), CGM.getContext().IntTy,
ImplicitParamDecl::Other);
Args.push_back(&IPD);
QualType ResTy = CGM.getContext().IntTy;
CGF.StartFunction(GlobalDecl(&D, DynamicInitKind::AtExit), ResTy, DtorStub,
FI, Args, D.getLocation(), D.getInit()->getExprLoc());
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(CGF);
llvm::CallInst *call = CGF.Builder.CreateCall(Dtor, Addr);
// Make sure the call and the callee agree on calling convention.
if (auto *DtorFn = dyn_cast<llvm::Function>(
Dtor.getCallee()->stripPointerCastsAndAliases()))
call->setCallingConv(DtorFn->getCallingConv());
// Return 0 from function
CGF.Builder.CreateStore(llvm::Constant::getNullValue(CGM.IntTy),
CGF.ReturnValue);
CGF.FinishFunction();
return DtorStub;
}
/// Register a global destructor using the C atexit runtime function.
void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
llvm::FunctionCallee dtor,
llvm::Constant *addr) {
// Create a function which calls the destructor.
llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);
registerGlobalDtorWithAtExit(dtorStub);
}
void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtorStub) {
// extern "C" int atexit(void (*f)(void));
assert(dtorStub->getType() ==
llvm::PointerType::get(
llvm::FunctionType::get(CGM.VoidTy, false),
dtorStub->getType()->getPointerAddressSpace()) &&
"Argument to atexit has a wrong type.");
llvm::FunctionType *atexitTy =
llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
llvm::FunctionCallee atexit =
CGM.CreateRuntimeFunction(atexitTy, "atexit", llvm::AttributeList(),
/*Local=*/true);
if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit.getCallee()))
atexitFn->setDoesNotThrow();
EmitNounwindRuntimeCall(atexit, dtorStub);
}
llvm::Value *
CodeGenFunction::unregisterGlobalDtorWithUnAtExit(llvm::Constant *dtorStub) {
// The unatexit subroutine unregisters __dtor functions that were previously
// registered by the atexit subroutine. If the referenced function is found,
// it is removed from the list of functions that are called at normal program
// termination and the unatexit returns a value of 0, otherwise a non-zero
// value is returned.
//
// extern "C" int unatexit(void (*f)(void));
assert(dtorStub->getType() ==
llvm::PointerType::get(
llvm::FunctionType::get(CGM.VoidTy, false),
dtorStub->getType()->getPointerAddressSpace()) &&
"Argument to unatexit has a wrong type.");
llvm::FunctionType *unatexitTy =
llvm::FunctionType::get(IntTy, {dtorStub->getType()}, /*isVarArg=*/false);
llvm::FunctionCallee unatexit =
CGM.CreateRuntimeFunction(unatexitTy, "unatexit", llvm::AttributeList());
cast<llvm::Function>(unatexit.getCallee())->setDoesNotThrow();
return EmitNounwindRuntimeCall(unatexit, dtorStub);
}
void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit) {
// If we've been asked to forbid guard variables, emit an error now.
// This diagnostic is hard-coded for Darwin's use case; we can find
// better phrasing if someone else needs it.
if (CGM.getCodeGenOpts().ForbidGuardVariables)
CGM.Error(D.getLocation(),
"this initialization requires a guard variable, which "
"the kernel does not support");
CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
}
void CodeGenFunction::EmitCXXGuardedInitBranch(llvm::Value *NeedsInit,
llvm::BasicBlock *InitBlock,
llvm::BasicBlock *NoInitBlock,
GuardKind Kind,
const VarDecl *D) {
assert((Kind == GuardKind::TlsGuard || D) && "no guarded variable");
// A guess at how many times we will enter the initialization of a
// variable, depending on the kind of variable.
static const uint64_t InitsPerTLSVar = 1024;
static const uint64_t InitsPerLocalVar = 1024 * 1024;
llvm::MDNode *Weights;
if (Kind == GuardKind::VariableGuard && !D->isLocalVarDecl()) {
// For non-local variables, don't apply any weighting for now. Due to our
// use of COMDATs, we expect there to be at most one initialization of the
// variable per DSO, but we have no way to know how many DSOs will try to
// initialize the variable.
Weights = nullptr;
} else {
uint64_t NumInits;
// FIXME: For the TLS case, collect and use profiling information to
// determine a more accurate brach weight.
if (Kind == GuardKind::TlsGuard || D->getTLSKind())
NumInits = InitsPerTLSVar;
else
NumInits = InitsPerLocalVar;
// The probability of us entering the initializer is
// 1 / (total number of times we attempt to initialize the variable).
llvm::MDBuilder MDHelper(CGM.getLLVMContext());
Weights = MDHelper.createBranchWeights(1, NumInits - 1);
}
Builder.CreateCondBr(NeedsInit, InitBlock, NoInitBlock, Weights);
}
llvm::Function *CodeGenModule::CreateGlobalInitOrCleanUpFunction(
llvm::FunctionType *FTy, const Twine &Name, const CGFunctionInfo &FI,
SourceLocation Loc, bool TLS, llvm::GlobalVariable::LinkageTypes Linkage) {
llvm::Function *Fn = llvm::Function::Create(FTy, Linkage, Name, &getModule());
if (!getLangOpts().AppleKext && !TLS) {
// Set the section if needed.
if (const char *Section = getTarget().getStaticInitSectionSpecifier())
Fn->setSection(Section);
}
if (Linkage == llvm::GlobalVariable::InternalLinkage)
SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
Fn->setCallingConv(getRuntimeCC());
if (!getLangOpts().Exceptions)
Fn->setDoesNotThrow();
if (getLangOpts().Sanitize.has(SanitizerKind::Address) &&
!isInNoSanitizeList(SanitizerKind::Address, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
if (getLangOpts().Sanitize.has(SanitizerKind::KernelAddress) &&
!isInNoSanitizeList(SanitizerKind::KernelAddress, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
if (getLangOpts().Sanitize.has(SanitizerKind::HWAddress) &&
!isInNoSanitizeList(SanitizerKind::HWAddress, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
if (getLangOpts().Sanitize.has(SanitizerKind::KernelHWAddress) &&
!isInNoSanitizeList(SanitizerKind::KernelHWAddress, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
if (getLangOpts().Sanitize.has(SanitizerKind::MemtagStack) &&
!isInNoSanitizeList(SanitizerKind::MemtagStack, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeMemTag);
if (getLangOpts().Sanitize.has(SanitizerKind::Thread) &&
!isInNoSanitizeList(SanitizerKind::Thread, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeThread);
if (getLangOpts().Sanitize.has(SanitizerKind::Memory) &&
!isInNoSanitizeList(SanitizerKind::Memory, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
if (getLangOpts().Sanitize.has(SanitizerKind::KernelMemory) &&
!isInNoSanitizeList(SanitizerKind::KernelMemory, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack) &&
!isInNoSanitizeList(SanitizerKind::SafeStack, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::SafeStack);
if (getLangOpts().Sanitize.has(SanitizerKind::ShadowCallStack) &&
!isInNoSanitizeList(SanitizerKind::ShadowCallStack, Fn, Loc))
Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
return Fn;
}
/// Create a global pointer to a function that will initialize a global
/// variable. The user has requested that this pointer be emitted in a specific
/// section.
void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
llvm::GlobalVariable *GV,
llvm::Function *InitFunc,
InitSegAttr *ISA) {
llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
TheModule, InitFunc->getType(), /*isConstant=*/true,
llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
PtrArray->setSection(ISA->getSection());
addUsedGlobal(PtrArray);
// If the GV is already in a comdat group, then we have to join it.
if (llvm::Comdat *C = GV->getComdat())
PtrArray->setComdat(C);
}
void
CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
llvm::GlobalVariable *Addr,
bool PerformInit) {
// According to E.2.3.1 in CUDA-7.5 Programming guide: __device__,
// __constant__ and __shared__ variables defined in namespace scope,
// that are of class type, cannot have a non-empty constructor. All
// the checks have been done in Sema by now. Whatever initializers
// are allowed are empty and we just need to ignore them here.
if (getLangOpts().CUDAIsDevice && !getLangOpts().GPUAllowDeviceInit &&
(D->hasAttr<CUDADeviceAttr>() || D->hasAttr<CUDAConstantAttr>() ||
D->hasAttr<CUDASharedAttr>()))
return;
if (getLangOpts().OpenMP &&
getOpenMPRuntime().emitDeclareTargetVarDefinition(D, Addr, PerformInit))
return;
// Check if we've already initialized this decl.
auto I = DelayedCXXInitPosition.find(D);
if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
return;
llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
SmallString<256> FnName;
{
llvm::raw_svector_ostream Out(FnName);
getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
}
// Create a variable initialization function.
llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
FTy, FnName.str(), getTypes().arrangeNullaryFunction(), D->getLocation());
auto *ISA = D->getAttr<InitSegAttr>();
CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
PerformInit);
llvm::GlobalVariable *COMDATKey =
supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
if (D->getTLSKind()) {
// FIXME: Should we support init_priority for thread_local?
// FIXME: We only need to register one __cxa_thread_atexit function for the
// entire TU.
CXXThreadLocalInits.push_back(Fn);
CXXThreadLocalInitVars.push_back(D);
} else if (PerformInit && ISA) {
EmitPointerToInitFunc(D, Addr, Fn, ISA);
} else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
OrderGlobalInitsOrStermFinalizers Key(IPA->getPriority(),
PrioritizedCXXGlobalInits.size());
PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
} else if (isTemplateInstantiation(D->getTemplateSpecializationKind()) ||
getContext().GetGVALinkageForVariable(D) == GVA_DiscardableODR ||
D->hasAttr<SelectAnyAttr>()) {
// C++ [basic.start.init]p2:
// Definitions of explicitly specialized class template static data
// members have ordered initialization. Other class template static data
// members (i.e., implicitly or explicitly instantiated specializations)
// have unordered initialization.
//
// As a consequence, we can put them into their own llvm.global_ctors entry.
//
// If the global is externally visible, put the initializer into a COMDAT
// group with the global being initialized. On most platforms, this is a
// minor startup time optimization. In the MS C++ ABI, there are no guard
// variables, so this COMDAT key is required for correctness.
//
// SelectAny globals will be comdat-folded. Put the initializer into a
// COMDAT group associated with the global, so the initializers get folded
// too.
AddGlobalCtor(Fn, 65535, COMDATKey);
if (COMDATKey && (getTriple().isOSBinFormatELF() ||
getTarget().getCXXABI().isMicrosoft())) {
// When COMDAT is used on ELF or in the MS C++ ABI, the key must be in
// llvm.used to prevent linker GC.
addUsedGlobal(COMDATKey);
}
// If we used a COMDAT key for the global ctor, the init function can be
// discarded if the global ctor entry is discarded.
// FIXME: Do we need to restrict this to ELF and Wasm?
llvm::Comdat *C = Addr->getComdat();
if (COMDATKey && C &&
(getTarget().getTriple().isOSBinFormatELF() ||
getTarget().getTriple().isOSBinFormatWasm())) {
Fn->setComdat(C);
}
} else {
I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
if (I == DelayedCXXInitPosition.end()) {
CXXGlobalInits.push_back(Fn);
} else if (I->second != ~0U) {
assert(I->second < CXXGlobalInits.size() &&
CXXGlobalInits[I->second] == nullptr);
CXXGlobalInits[I->second] = Fn;
}
}
// Remember that we already emitted the initializer for this global.
DelayedCXXInitPosition[D] = ~0U;
}
void CodeGenModule::EmitCXXThreadLocalInitFunc() {
getCXXABI().EmitThreadLocalInitFuncs(
*this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
CXXThreadLocalInits.clear();
CXXThreadLocalInitVars.clear();
CXXThreadLocals.clear();
}
static SmallString<128> getTransformedFileName(llvm::Module &M) {
SmallString<128> FileName = llvm::sys::path::filename(M.getName());
if (FileName.empty())
FileName = "<null>";
for (size_t i = 0; i < FileName.size(); ++i) {
// Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
// to be the set of C preprocessing numbers.
if (!isPreprocessingNumberBody(FileName[i]))
FileName[i] = '_';
}
return FileName;
}
static std::string getPrioritySuffix(unsigned int Priority) {
assert(Priority <= 65535 && "Priority should always be <= 65535.");
// Compute the function suffix from priority. Prepend with zeroes to make
// sure the function names are also ordered as priorities.
std::string PrioritySuffix = llvm::utostr(Priority);
PrioritySuffix = std::string(6 - PrioritySuffix.size(), '0') + PrioritySuffix;
return PrioritySuffix;
}
void
CodeGenModule::EmitCXXGlobalInitFunc() {
while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
CXXGlobalInits.pop_back();
if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
return;
llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
// Create our global prioritized initialization function.
if (!PrioritizedCXXGlobalInits.empty()) {
SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
PrioritizedCXXGlobalInits.end());
// Iterate over "chunks" of ctors with same priority and emit each chunk
// into separate function. Note - everything is sorted first by priority,
// second - by lex order, so we emit ctor functions in proper order.
for (SmallVectorImpl<GlobalInitData >::iterator
I = PrioritizedCXXGlobalInits.begin(),
E = PrioritizedCXXGlobalInits.end(); I != E; ) {
SmallVectorImpl<GlobalInitData >::iterator
PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
LocalCXXGlobalInits.clear();
unsigned int Priority = I->first.priority;
llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
FTy, "_GLOBAL__I_" + getPrioritySuffix(Priority), FI);
for (; I < PrioE; ++I)
LocalCXXGlobalInits.push_back(I->second);
CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
AddGlobalCtor(Fn, Priority);
}
PrioritizedCXXGlobalInits.clear();
}
if (getCXXABI().useSinitAndSterm() && CXXGlobalInits.empty())
return;
// Include the filename in the symbol name. Including "sub_" matches gcc
// and makes sure these symbols appear lexicographically behind the symbols
// with priority emitted above.
llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
FTy, llvm::Twine("_GLOBAL__sub_I_", getTransformedFileName(getModule())),
FI);
CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
AddGlobalCtor(Fn);
// In OpenCL global init functions must be converted to kernels in order to
// be able to launch them from the host.
// FIXME: Some more work might be needed to handle destructors correctly.
// Current initialization function makes use of function pointers callbacks.
// We can't support function pointers especially between host and device.
// However it seems global destruction has little meaning without any
// dynamic resource allocation on the device and program scope variables are
// destroyed by the runtime when program is released.
if (getLangOpts().OpenCL) {
GenKernelArgMetadata(Fn);
Fn->setCallingConv(llvm::CallingConv::SPIR_KERNEL);
}
assert(!getLangOpts().CUDA || !getLangOpts().CUDAIsDevice ||
getLangOpts().GPUAllowDeviceInit);
if (getLangOpts().HIP && getLangOpts().CUDAIsDevice) {
Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
Fn->addFnAttr("device-init");
}
CXXGlobalInits.clear();
}
void CodeGenModule::EmitCXXGlobalCleanUpFunc() {
if (CXXGlobalDtorsOrStermFinalizers.empty() &&
PrioritizedCXXStermFinalizers.empty())
return;
llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
// Create our global prioritized cleanup function.
if (!PrioritizedCXXStermFinalizers.empty()) {
SmallVector<CXXGlobalDtorsOrStermFinalizer_t, 8> LocalCXXStermFinalizers;
llvm::array_pod_sort(PrioritizedCXXStermFinalizers.begin(),
PrioritizedCXXStermFinalizers.end());
// Iterate over "chunks" of dtors with same priority and emit each chunk
// into separate function. Note - everything is sorted first by priority,
// second - by lex order, so we emit dtor functions in proper order.
for (SmallVectorImpl<StermFinalizerData>::iterator
I = PrioritizedCXXStermFinalizers.begin(),
E = PrioritizedCXXStermFinalizers.end();
I != E;) {
SmallVectorImpl<StermFinalizerData>::iterator PrioE =
std::upper_bound(I + 1, E, *I, StermFinalizerPriorityCmp());
LocalCXXStermFinalizers.clear();
unsigned int Priority = I->first.priority;
llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
FTy, "_GLOBAL__a_" + getPrioritySuffix(Priority), FI);
for (; I < PrioE; ++I) {
llvm::FunctionCallee DtorFn = I->second;
LocalCXXStermFinalizers.emplace_back(DtorFn.getFunctionType(),
DtorFn.getCallee(), nullptr);
}
CodeGenFunction(*this).GenerateCXXGlobalCleanUpFunc(
Fn, LocalCXXStermFinalizers);
AddGlobalDtor(Fn, Priority);
}
PrioritizedCXXStermFinalizers.clear();
}
if (CXXGlobalDtorsOrStermFinalizers.empty())
return;
// Create our global cleanup function.
llvm::Function *Fn =
CreateGlobalInitOrCleanUpFunction(FTy, "_GLOBAL__D_a", FI);
CodeGenFunction(*this).GenerateCXXGlobalCleanUpFunc(
Fn, CXXGlobalDtorsOrStermFinalizers);
AddGlobalDtor(Fn);
CXXGlobalDtorsOrStermFinalizers.clear();
}
/// Emit the code necessary to initialize the given global variable.
void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
const VarDecl *D,
llvm::GlobalVariable *Addr,
bool PerformInit) {
// Check if we need to emit debug info for variable initializer.
if (D->hasAttr<NoDebugAttr>())
DebugInfo = nullptr; // disable debug info indefinitely for this function
CurEHLocation = D->getBeginLoc();
StartFunction(GlobalDecl(D, DynamicInitKind::Initializer),
getContext().VoidTy, Fn, getTypes().arrangeNullaryFunction(),
FunctionArgList());
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(*this);
// Use guarded initialization if the global variable is weak. This
// occurs for, e.g., instantiated static data members and
// definitions explicitly marked weak.
//
// Also use guarded initialization for a variable with dynamic TLS and
// unordered initialization. (If the initialization is ordered, the ABI
// layer will guard the whole-TU initialization for us.)
if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage() ||
(D->getTLSKind() == VarDecl::TLS_Dynamic &&
isTemplateInstantiation(D->getTemplateSpecializationKind()))) {
EmitCXXGuardedInit(*D, Addr, PerformInit);
} else {
EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
}
FinishFunction();
}
void
CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
ArrayRef<llvm::Function *> Decls,
ConstantAddress Guard) {
{
auto NL = ApplyDebugLocation::CreateEmpty(*this);
StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
getTypes().arrangeNullaryFunction(), FunctionArgList());
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(*this);
llvm::BasicBlock *ExitBlock = nullptr;
if (Guard.isValid()) {
// If we have a guard variable, check whether we've already performed
// these initializations. This happens for TLS initialization functions.
llvm::Value *GuardVal = Builder.CreateLoad(Guard);
llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
"guard.uninitialized");
llvm::BasicBlock *InitBlock = createBasicBlock("init");
ExitBlock = createBasicBlock("exit");
EmitCXXGuardedInitBranch(Uninit, InitBlock, ExitBlock,
GuardKind::TlsGuard, nullptr);
EmitBlock(InitBlock);
// Mark as initialized before initializing anything else. If the
// initializers use previously-initialized thread_local vars, that's
// probably supposed to be OK, but the standard doesn't say.
Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
// The guard variable can't ever change again.
EmitInvariantStart(
Guard.getPointer(),
CharUnits::fromQuantity(
CGM.getDataLayout().getTypeAllocSize(GuardVal->getType())));
}
RunCleanupsScope Scope(*this);
// When building in Objective-C++ ARC mode, create an autorelease pool
// around the global initializers.
if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
llvm::Value *token = EmitObjCAutoreleasePoolPush();
EmitObjCAutoreleasePoolCleanup(token);
}
for (unsigned i = 0, e = Decls.size(); i != e; ++i)
if (Decls[i])
EmitRuntimeCall(Decls[i]);
Scope.ForceCleanup();
if (ExitBlock) {
Builder.CreateBr(ExitBlock);
EmitBlock(ExitBlock);
}
}
FinishFunction();
}
void CodeGenFunction::GenerateCXXGlobalCleanUpFunc(
llvm::Function *Fn,
ArrayRef<std::tuple<llvm::FunctionType *, llvm::WeakTrackingVH,
llvm::Constant *>>
DtorsOrStermFinalizers) {
{
auto NL = ApplyDebugLocation::CreateEmpty(*this);
StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
getTypes().arrangeNullaryFunction(), FunctionArgList());
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(*this);
// Emit the cleanups, in reverse order from construction.
for (unsigned i = 0, e = DtorsOrStermFinalizers.size(); i != e; ++i) {
llvm::FunctionType *CalleeTy;
llvm::Value *Callee;
llvm::Constant *Arg;
std::tie(CalleeTy, Callee, Arg) = DtorsOrStermFinalizers[e - i - 1];
llvm::CallInst *CI = nullptr;
if (Arg == nullptr) {
assert(
CGM.getCXXABI().useSinitAndSterm() &&
"Arg could not be nullptr unless using sinit and sterm functions.");
CI = Builder.CreateCall(CalleeTy, Callee);
} else
CI = Builder.CreateCall(CalleeTy, Callee, Arg);
// Make sure the call and the callee agree on calling convention.
if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
CI->setCallingConv(F->getCallingConv());
}
}
FinishFunction();
}
/// generateDestroyHelper - Generates a helper function which, when
/// invoked, destroys the given object. The address of the object
/// should be in global memory.
llvm::Function *CodeGenFunction::generateDestroyHelper(
Address addr, QualType type, Destroyer *destroyer,
bool useEHCleanupForArray, const VarDecl *VD) {
FunctionArgList args;
ImplicitParamDecl Dst(getContext(), getContext().VoidPtrTy,
ImplicitParamDecl::Other);
args.push_back(&Dst);
const CGFunctionInfo &FI =
CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, args);
llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
FTy, "__cxx_global_array_dtor", FI, VD->getLocation());
CurEHLocation = VD->getBeginLoc();
StartFunction(GlobalDecl(VD, DynamicInitKind::GlobalArrayDestructor),
getContext().VoidTy, fn, FI, args);
// Emit an artificial location for this function.
auto AL = ApplyDebugLocation::CreateArtificial(*this);
emitDestroy(addr, type, destroyer, useEHCleanupForArray);
FinishFunction();
return fn;
}