llvm-project/clang/lib/CodeGen/CGDeclCXX.cpp

487 lines
17 KiB
C++

//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with code generation of C++ declarations
//
//===----------------------------------------------------------------------===//
#include "CodeGenFunction.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::Constant *DeclPtr) {
assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
assert(!D.getType()->isReferenceType() &&
"Should not call EmitDeclInit on a reference!");
ASTContext &Context = CGF.getContext();
const Expr *Init = D.getInit();
QualType T = D.getType();
bool isVolatile = Context.getCanonicalType(T).isVolatileQualified();
if (!CGF.hasAggregateLLVMType(T)) {
llvm::Value *V = CGF.EmitScalarExpr(Init);
CGF.EmitStoreOfScalar(V, DeclPtr, isVolatile, T);
} else if (T->isAnyComplexType()) {
CGF.EmitComplexExprIntoAddr(Init, DeclPtr, isVolatile);
} else {
CGF.EmitAggExpr(Init, DeclPtr, isVolatile);
}
}
static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
llvm::Constant *DeclPtr) {
CodeGenModule &CGM = CGF.CGM;
ASTContext &Context = CGF.getContext();
const Expr *Init = D.getInit();
QualType T = D.getType();
if (!CGF.hasAggregateLLVMType(T) || T->isAnyComplexType())
return;
// Avoid generating destructor(s) for initialized objects.
if (!isa<CXXConstructExpr>(Init))
return;
const ConstantArrayType *Array = Context.getAsConstantArrayType(T);
if (Array)
T = Context.getBaseElementType(Array);
const RecordType *RT = T->getAs<RecordType>();
if (!RT)
return;
CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
if (RD->hasTrivialDestructor())
return;
CXXDestructorDecl *Dtor = RD->getDestructor(Context);
llvm::Constant *DtorFn;
if (Array) {
DtorFn =
CodeGenFunction(CGM).GenerateCXXAggrDestructorHelper(Dtor, Array,
DeclPtr);
const llvm::Type *Int8PtrTy =
llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
DeclPtr = llvm::Constant::getNullValue(Int8PtrTy);
} else
DtorFn = CGM.GetAddrOfCXXDestructor(Dtor, Dtor_Complete);
CGF.EmitCXXGlobalDtorRegistration(DtorFn, DeclPtr);
}
void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
llvm::Constant *DeclPtr) {
const Expr *Init = D.getInit();
QualType T = D.getType();
if (!T->isReferenceType()) {
EmitDeclInit(*this, D, DeclPtr);
EmitDeclDestroy(*this, D, DeclPtr);
return;
}
if (Init->isLvalue(getContext()) == Expr::LV_Valid) {
RValue RV = EmitReferenceBindingToExpr(Init, /*IsInitializer=*/true);
EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, T);
return;
}
ErrorUnsupported(Init,
"global variable that binds reference to a non-lvalue");
}
void
CodeGenFunction::EmitCXXGlobalDtorRegistration(llvm::Constant *DtorFn,
llvm::Constant *DeclPtr) {
// Generate a global destructor entry if not using __cxa_atexit.
if (!CGM.getCodeGenOpts().CXAAtExit) {
CGM.AddCXXDtorEntry(DtorFn, DeclPtr);
return;
}
const llvm::Type *Int8PtrTy =
llvm::Type::getInt8Ty(VMContext)->getPointerTo();
std::vector<const llvm::Type *> Params;
Params.push_back(Int8PtrTy);
// Get the destructor function type
const llvm::Type *DtorFnTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext), Params, false);
DtorFnTy = llvm::PointerType::getUnqual(DtorFnTy);
Params.clear();
Params.push_back(DtorFnTy);
Params.push_back(Int8PtrTy);
Params.push_back(Int8PtrTy);
// Get the __cxa_atexit function type
// extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d );
const llvm::FunctionType *AtExitFnTy =
llvm::FunctionType::get(ConvertType(getContext().IntTy), Params, false);
llvm::Constant *AtExitFn = CGM.CreateRuntimeFunction(AtExitFnTy,
"__cxa_atexit");
llvm::Constant *Handle = CGM.CreateRuntimeVariable(Int8PtrTy,
"__dso_handle");
llvm::Value *Args[3] = { llvm::ConstantExpr::getBitCast(DtorFn, DtorFnTy),
llvm::ConstantExpr::getBitCast(DeclPtr, Int8PtrTy),
llvm::ConstantExpr::getBitCast(Handle, Int8PtrTy) };
Builder.CreateCall(AtExitFn, &Args[0], llvm::array_endof(Args));
}
static llvm::Function *
CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
const llvm::FunctionType *FTy,
llvm::StringRef Name) {
llvm::Function *Fn =
llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
Name, &CGM.getModule());
// Set the section if needed.
if (const char *Section =
CGM.getContext().Target.getStaticInitSectionSpecifier())
Fn->setSection(Section);
return Fn;
}
void
CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D) {
const llvm::FunctionType *FTy
= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
false);
// Create a variable initialization function.
llvm::Function *Fn =
CreateGlobalInitOrDestructFunction(*this, FTy, "__cxx_global_var_init");
CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D);
if (D->hasAttr<InitPriorityAttr>()) {
unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority();
OrderGlobalInitsType Key(order, PrioritizedCXXGlobalInits.size());
PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
}
else
CXXGlobalInits.push_back(Fn);
}
void
CodeGenModule::EmitCXXGlobalInitFunc() {
if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
return;
const llvm::FunctionType *FTy
= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
false);
// Create our global initialization function.
llvm::Function *Fn =
CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a");
if (!PrioritizedCXXGlobalInits.empty()) {
llvm::SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits;
llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
PrioritizedCXXGlobalInits.end());
for (unsigned i = 0; i < PrioritizedCXXGlobalInits.size(); i++) {
llvm::Function *Fn = PrioritizedCXXGlobalInits[i].second;
LocalCXXGlobalInits.push_back(Fn);
}
for (unsigned i = 0; i < CXXGlobalInits.size(); i++)
LocalCXXGlobalInits.push_back(CXXGlobalInits[i]);
CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
&LocalCXXGlobalInits[0],
LocalCXXGlobalInits.size());
}
else
CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
&CXXGlobalInits[0],
CXXGlobalInits.size());
AddGlobalCtor(Fn);
}
void CodeGenModule::EmitCXXGlobalDtorFunc() {
if (CXXGlobalDtors.empty())
return;
const llvm::FunctionType *FTy
= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
false);
// Create our global destructor function.
llvm::Function *Fn =
CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a");
CodeGenFunction(*this).GenerateCXXGlobalDtorFunc(Fn, CXXGlobalDtors);
AddGlobalDtor(Fn);
}
void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
const VarDecl *D) {
StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
SourceLocation());
llvm::Constant *DeclPtr = CGM.GetAddrOfGlobalVar(D);
EmitCXXGlobalVarDeclInit(*D, DeclPtr);
FinishFunction();
}
void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
llvm::Constant **Decls,
unsigned NumDecls) {
StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
SourceLocation());
for (unsigned i = 0; i != NumDecls; ++i)
Builder.CreateCall(Decls[i]);
FinishFunction();
}
void CodeGenFunction::GenerateCXXGlobalDtorFunc(llvm::Function *Fn,
const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
&DtorsAndObjects) {
StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
SourceLocation());
// Emit the dtors, in reverse order from construction.
for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
llvm::CallInst *CI = Builder.CreateCall(Callee,
DtorsAndObjects[e - i - 1].second);
// 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();
}
static llvm::Constant *getGuardAcquireFn(CodeGenFunction &CGF) {
// int __cxa_guard_acquire(__int64_t *guard_object);
const llvm::Type *Int64PtrTy =
llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
std::vector<const llvm::Type*> Args(1, Int64PtrTy);
const llvm::FunctionType *FTy =
llvm::FunctionType::get(CGF.ConvertType(CGF.getContext().IntTy),
Args, /*isVarArg=*/false);
return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire");
}
static llvm::Constant *getGuardReleaseFn(CodeGenFunction &CGF) {
// void __cxa_guard_release(__int64_t *guard_object);
const llvm::Type *Int64PtrTy =
llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
std::vector<const llvm::Type*> Args(1, Int64PtrTy);
const llvm::FunctionType *FTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
Args, /*isVarArg=*/false);
return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release");
}
static llvm::Constant *getGuardAbortFn(CodeGenFunction &CGF) {
// void __cxa_guard_abort(__int64_t *guard_object);
const llvm::Type *Int64PtrTy =
llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
std::vector<const llvm::Type*> Args(1, Int64PtrTy);
const llvm::FunctionType *FTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
Args, /*isVarArg=*/false);
return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort");
}
void
CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
llvm::GlobalVariable *GV) {
// Bail out early if this initializer isn't reachable.
if (!Builder.GetInsertBlock()) return;
bool ThreadsafeStatics = getContext().getLangOptions().ThreadsafeStatics;
llvm::SmallString<256> GuardVName;
CGM.getMangleContext().mangleGuardVariable(&D, GuardVName);
// Create the guard variable.
const llvm::Type *Int64Ty = llvm::Type::getInt64Ty(VMContext);
llvm::GlobalValue *GuardVariable =
new llvm::GlobalVariable(CGM.getModule(), Int64Ty,
false, GV->getLinkage(),
llvm::Constant::getNullValue(Int64Ty),
GuardVName.str());
// Load the first byte of the guard variable.
const llvm::Type *PtrTy
= llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext), 0);
llvm::Value *V =
Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy), "tmp");
llvm::BasicBlock *InitCheckBlock = createBasicBlock("init.check");
llvm::BasicBlock *EndBlock = createBasicBlock("init.end");
// Check if the first byte of the guard variable is zero.
Builder.CreateCondBr(Builder.CreateIsNull(V, "tobool"),
InitCheckBlock, EndBlock);
EmitBlock(InitCheckBlock);
// Variables used when coping with thread-safe statics and exceptions.
llvm::BasicBlock *SavedLandingPad = 0;
llvm::BasicBlock *LandingPad = 0;
if (ThreadsafeStatics) {
// Call __cxa_guard_acquire.
V = Builder.CreateCall(getGuardAcquireFn(*this), GuardVariable);
llvm::BasicBlock *InitBlock = createBasicBlock("init");
Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
InitBlock, EndBlock);
if (Exceptions) {
SavedLandingPad = getInvokeDest();
LandingPad = createBasicBlock("guard.lpad");
setInvokeDest(LandingPad);
}
EmitBlock(InitBlock);
}
if (D.getType()->isReferenceType()) {
QualType T = D.getType();
// We don't want to pass true for IsInitializer here, because a static
// reference to a temporary does not extend its lifetime.
RValue RV = EmitReferenceBindingToExpr(D.getInit(),
/*IsInitializer=*/false);
EmitStoreOfScalar(RV.getScalarVal(), GV, /*Volatile=*/false, T);
} else
EmitDeclInit(*this, D, GV);
if (ThreadsafeStatics) {
// Call __cxa_guard_release.
Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);
} else {
llvm::Value *One =
llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), 1);
Builder.CreateStore(One, Builder.CreateBitCast(GuardVariable, PtrTy));
}
// Register the call to the destructor.
if (!D.getType()->isReferenceType())
EmitDeclDestroy(*this, D, GV);
if (ThreadsafeStatics && Exceptions) {
// If an exception is thrown during initialization, call __cxa_guard_abort
// along the exceptional edge.
EmitBranch(EndBlock);
// Construct the landing pad.
EmitBlock(LandingPad);
// Personality function and LLVM intrinsics.
llvm::Constant *Personality =
CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::getInt32Ty
(VMContext),
true),
"__gxx_personality_v0");
Personality = llvm::ConstantExpr::getBitCast(Personality, PtrToInt8Ty);
llvm::Value *llvm_eh_exception =
CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
llvm::Value *llvm_eh_selector =
CGM.getIntrinsic(llvm::Intrinsic::eh_selector);
// Exception object
llvm::Value *Exc = Builder.CreateCall(llvm_eh_exception, "exc");
llvm::Value *RethrowPtr = CreateTempAlloca(Exc->getType(), "_rethrow");
// Call the selector function.
const llvm::PointerType *PtrToInt8Ty
= llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
llvm::Constant *Null = llvm::ConstantPointerNull::get(PtrToInt8Ty);
llvm::Value* SelectorArgs[3] = { Exc, Personality, Null };
Builder.CreateCall(llvm_eh_selector, SelectorArgs, SelectorArgs + 3,
"selector");
Builder.CreateStore(Exc, RethrowPtr);
// Call __cxa_guard_abort along the exceptional edge.
Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
setInvokeDest(SavedLandingPad);
// Rethrow the current exception.
if (getInvokeDest()) {
llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
Builder.CreateInvoke(getUnwindResumeOrRethrowFn(), Cont,
getInvokeDest(),
Builder.CreateLoad(RethrowPtr));
EmitBlock(Cont);
} else
Builder.CreateCall(getUnwindResumeOrRethrowFn(),
Builder.CreateLoad(RethrowPtr));
Builder.CreateUnreachable();
}
EmitBlock(EndBlock);
}
/// GenerateCXXAggrDestructorHelper - Generates a helper function which when
/// invoked, calls the default destructor on array elements in reverse order of
/// construction.
llvm::Function *
CodeGenFunction::GenerateCXXAggrDestructorHelper(const CXXDestructorDecl *D,
const ArrayType *Array,
llvm::Value *This) {
FunctionArgList Args;
ImplicitParamDecl *Dst =
ImplicitParamDecl::Create(getContext(), 0,
SourceLocation(), 0,
getContext().getPointerType(getContext().VoidTy));
Args.push_back(std::make_pair(Dst, Dst->getType()));
const CGFunctionInfo &FI =
CGM.getTypes().getFunctionInfo(getContext().VoidTy, Args,
FunctionType::ExtInfo());
const llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI, false);
llvm::Function *Fn =
CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor");
StartFunction(GlobalDecl(), getContext().VoidTy, Fn, Args, SourceLocation());
QualType BaseElementTy = getContext().getBaseElementType(Array);
const llvm::Type *BasePtr = ConvertType(BaseElementTy)->getPointerTo();
llvm::Value *BaseAddrPtr = Builder.CreateBitCast(This, BasePtr);
EmitCXXAggrDestructorCall(D, Array, BaseAddrPtr);
FinishFunction();
return Fn;
}