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4a39ab8078
they're unreachable. This matters because (if they're POD, or if this is C) the scope containing the variable might be reachable even if the variable isn't. Fixes PR7044. llvm-svn: 103052
354 lines
12 KiB
C++
354 lines
12 KiB
C++
//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with code generation of C++ declarations
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenFunction.h"
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#include "clang/CodeGen/CodeGenOptions.h"
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using namespace clang;
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using namespace CodeGen;
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static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
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llvm::Constant *DeclPtr) {
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assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
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assert(!D.getType()->isReferenceType() &&
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"Should not call EmitDeclInit on a reference!");
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CodeGenModule &CGM = CGF.CGM;
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ASTContext &Context = CGF.getContext();
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const Expr *Init = D.getInit();
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QualType T = D.getType();
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bool isVolatile = Context.getCanonicalType(T).isVolatileQualified();
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if (!CGF.hasAggregateLLVMType(T)) {
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llvm::Value *V = CGF.EmitScalarExpr(Init);
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CGF.EmitStoreOfScalar(V, DeclPtr, isVolatile, T);
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} else if (T->isAnyComplexType()) {
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CGF.EmitComplexExprIntoAddr(Init, DeclPtr, isVolatile);
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} else {
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CGF.EmitAggExpr(Init, DeclPtr, isVolatile);
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// Avoid generating destructor(s) for initialized objects.
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if (!isa<CXXConstructExpr>(Init))
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return;
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const ConstantArrayType *Array = Context.getAsConstantArrayType(T);
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if (Array)
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T = Context.getBaseElementType(Array);
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const RecordType *RT = T->getAs<RecordType>();
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if (!RT)
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return;
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CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
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if (RD->hasTrivialDestructor())
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return;
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CXXDestructorDecl *Dtor = RD->getDestructor(Context);
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llvm::Constant *DtorFn;
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if (Array) {
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DtorFn =
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CodeGenFunction(CGM).GenerateCXXAggrDestructorHelper(Dtor,
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Array,
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DeclPtr);
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const llvm::Type *Int8PtrTy =
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llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
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DeclPtr = llvm::Constant::getNullValue(Int8PtrTy);
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} else
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DtorFn = CGM.GetAddrOfCXXDestructor(Dtor, Dtor_Complete);
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CGF.EmitCXXGlobalDtorRegistration(DtorFn, DeclPtr);
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}
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}
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void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
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llvm::Constant *DeclPtr) {
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const Expr *Init = D.getInit();
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QualType T = D.getType();
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if (!T->isReferenceType()) {
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EmitDeclInit(*this, D, DeclPtr);
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return;
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}
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if (Init->isLvalue(getContext()) == Expr::LV_Valid) {
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RValue RV = EmitReferenceBindingToExpr(Init, /*IsInitializer=*/true);
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EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, T);
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return;
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}
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ErrorUnsupported(Init,
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"global variable that binds reference to a non-lvalue");
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}
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void
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CodeGenFunction::EmitCXXGlobalDtorRegistration(llvm::Constant *DtorFn,
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llvm::Constant *DeclPtr) {
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// Generate a global destructor entry if not using __cxa_atexit.
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if (!CGM.getCodeGenOpts().CXAAtExit) {
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CGM.AddCXXDtorEntry(DtorFn, DeclPtr);
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return;
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}
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const llvm::Type *Int8PtrTy =
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llvm::Type::getInt8Ty(VMContext)->getPointerTo();
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std::vector<const llvm::Type *> Params;
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Params.push_back(Int8PtrTy);
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// Get the destructor function type
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const llvm::Type *DtorFnTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext), Params, false);
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DtorFnTy = llvm::PointerType::getUnqual(DtorFnTy);
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Params.clear();
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Params.push_back(DtorFnTy);
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Params.push_back(Int8PtrTy);
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Params.push_back(Int8PtrTy);
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// Get the __cxa_atexit function type
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// extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d );
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const llvm::FunctionType *AtExitFnTy =
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llvm::FunctionType::get(ConvertType(getContext().IntTy), Params, false);
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llvm::Constant *AtExitFn = CGM.CreateRuntimeFunction(AtExitFnTy,
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"__cxa_atexit");
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llvm::Constant *Handle = CGM.CreateRuntimeVariable(Int8PtrTy,
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"__dso_handle");
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llvm::Value *Args[3] = { llvm::ConstantExpr::getBitCast(DtorFn, DtorFnTy),
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llvm::ConstantExpr::getBitCast(DeclPtr, Int8PtrTy),
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llvm::ConstantExpr::getBitCast(Handle, Int8PtrTy) };
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Builder.CreateCall(AtExitFn, &Args[0], llvm::array_endof(Args));
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}
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void
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CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D) {
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const llvm::FunctionType *FTy
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= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
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false);
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// Create a variable initialization function.
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llvm::Function *Fn =
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llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
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"__cxx_global_var_init", &TheModule);
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CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D);
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CXXGlobalInits.push_back(Fn);
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}
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void
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CodeGenModule::EmitCXXGlobalInitFunc() {
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if (CXXGlobalInits.empty())
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return;
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const llvm::FunctionType *FTy
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= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
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false);
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// Create our global initialization function.
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llvm::Function *Fn =
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llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
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"_GLOBAL__I_a", &TheModule);
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CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
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&CXXGlobalInits[0],
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CXXGlobalInits.size());
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AddGlobalCtor(Fn);
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}
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void CodeGenModule::AddCXXDtorEntry(llvm::Constant *DtorFn,
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llvm::Constant *Object) {
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CXXGlobalDtors.push_back(std::make_pair(DtorFn, Object));
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}
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void CodeGenModule::EmitCXXGlobalDtorFunc() {
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if (CXXGlobalDtors.empty())
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return;
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const llvm::FunctionType *FTy
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= llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
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false);
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// Create our global destructor function.
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llvm::Function *Fn =
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llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
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"_GLOBAL__D_a", &TheModule);
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CodeGenFunction(*this).GenerateCXXGlobalDtorFunc(Fn, CXXGlobalDtors);
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AddGlobalDtor(Fn);
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}
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void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
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const VarDecl *D) {
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StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
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SourceLocation());
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llvm::Constant *DeclPtr = CGM.GetAddrOfGlobalVar(D);
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EmitCXXGlobalVarDeclInit(*D, DeclPtr);
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FinishFunction();
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}
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void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
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llvm::Constant **Decls,
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unsigned NumDecls) {
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StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
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SourceLocation());
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for (unsigned i = 0; i != NumDecls; ++i)
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Builder.CreateCall(Decls[i]);
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FinishFunction();
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}
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void CodeGenFunction::GenerateCXXGlobalDtorFunc(llvm::Function *Fn,
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const std::vector<std::pair<llvm::Constant*, llvm::Constant*> >
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&DtorsAndObjects) {
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StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
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SourceLocation());
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// Emit the dtors, in reverse order from construction.
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for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
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llvm::Constant *Callee = DtorsAndObjects[e - i - 1].first;
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llvm::CallInst *CI = Builder.CreateCall(Callee,
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DtorsAndObjects[e - i - 1].second);
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// Make sure the call and the callee agree on calling convention.
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if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
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CI->setCallingConv(F->getCallingConv());
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}
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FinishFunction();
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}
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static llvm::Constant *getGuardAcquireFn(CodeGenFunction &CGF) {
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// int __cxa_guard_acquire(__int64_t *guard_object);
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const llvm::Type *Int64PtrTy =
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llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
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std::vector<const llvm::Type*> Args(1, Int64PtrTy);
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(CGF.ConvertType(CGF.getContext().IntTy),
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Args, /*isVarArg=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire");
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}
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static llvm::Constant *getGuardReleaseFn(CodeGenFunction &CGF) {
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// void __cxa_guard_release(__int64_t *guard_object);
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const llvm::Type *Int64PtrTy =
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llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
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std::vector<const llvm::Type*> Args(1, Int64PtrTy);
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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Args, /*isVarArg=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release");
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}
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static llvm::Constant *getGuardAbortFn(CodeGenFunction &CGF) {
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// void __cxa_guard_abort(__int64_t *guard_object);
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const llvm::Type *Int64PtrTy =
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llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
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std::vector<const llvm::Type*> Args(1, Int64PtrTy);
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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Args, /*isVarArg=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort");
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}
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void
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CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
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llvm::GlobalVariable *GV) {
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// Bail out early if this initializer isn't reachable.
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if (!Builder.GetInsertBlock()) return;
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bool ThreadsafeStatics = getContext().getLangOptions().ThreadsafeStatics;
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llvm::SmallString<256> GuardVName;
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CGM.getMangleContext().mangleGuardVariable(&D, GuardVName);
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// Create the guard variable.
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const llvm::Type *Int64Ty = llvm::Type::getInt64Ty(VMContext);
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llvm::GlobalValue *GuardVariable =
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new llvm::GlobalVariable(CGM.getModule(), Int64Ty,
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false, GV->getLinkage(),
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llvm::Constant::getNullValue(Int64Ty),
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GuardVName.str());
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// Load the first byte of the guard variable.
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const llvm::Type *PtrTy
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= llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext), 0);
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llvm::Value *V =
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Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy), "tmp");
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llvm::BasicBlock *InitCheckBlock = createBasicBlock("init.check");
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llvm::BasicBlock *EndBlock = createBasicBlock("init.end");
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// Check if the first byte of the guard variable is zero.
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Builder.CreateCondBr(Builder.CreateIsNull(V, "tobool"),
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InitCheckBlock, EndBlock);
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EmitBlock(InitCheckBlock);
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if (ThreadsafeStatics) {
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// Call __cxa_guard_acquire.
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V = Builder.CreateCall(getGuardAcquireFn(*this), GuardVariable);
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llvm::BasicBlock *InitBlock = createBasicBlock("init");
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Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
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InitBlock, EndBlock);
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EmitBlock(InitBlock);
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if (Exceptions) {
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EHCleanupBlock Cleanup(*this);
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// Call __cxa_guard_abort.
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Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
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}
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}
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if (D.getType()->isReferenceType()) {
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QualType T = D.getType();
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// We don't want to pass true for IsInitializer here, because a static
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// reference to a temporary does not extend its lifetime.
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RValue RV = EmitReferenceBindingToExpr(D.getInit(),
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/*IsInitializer=*/false);
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EmitStoreOfScalar(RV.getScalarVal(), GV, /*Volatile=*/false, T);
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} else
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EmitDeclInit(*this, D, GV);
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if (ThreadsafeStatics) {
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// Call __cxa_guard_release.
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Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);
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} else {
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llvm::Value *One =
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llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), 1);
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Builder.CreateStore(One, Builder.CreateBitCast(GuardVariable, PtrTy));
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}
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EmitBlock(EndBlock);
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}
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