path: root/lib/CodeGen/CGCXX.cpp

//===--- CGDecl.cpp - Emit LLVM Code for 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 C++ code generation.
//
//===----------------------------------------------------------------------===//

// We might split this into multiple files if it gets too unwieldy 

#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "Mangle.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/ADT/StringExtras.h"
using namespace clang;
using namespace CodeGen;

void 
CodeGenFunction::EmitCXXGlobalDtorRegistration(const CXXDestructorDecl *Dtor,
                                               llvm::Constant *DeclPtr) {
  // FIXME: This is ABI dependent and we use the Itanium ABI.
  
  const llvm::Type *Int8PtrTy = 
    llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
  
  std::vector<const llvm::Type *> Params;
  Params.push_back(Int8PtrTy);
  
  // Get the destructor function type
  const llvm::Type *DtorFnTy = 
    llvm::FunctionType::get(llvm::Type::VoidTy, 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::Constant *DtorFn = CGM.GetAddrOfCXXDestructor(Dtor, Dtor_Complete);
  
  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));
}

void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D, 
                                               llvm::Constant *DeclPtr) {
  assert(D.hasGlobalStorage() &&
         "VarDecl must have global storage!");
  
  const Expr *Init = D.getInit();
  QualType T = D.getType();
  
  if (T->isReferenceType()) {
    ErrorUnsupported(Init, "Global variable that binds to a reference");
  } else if (!hasAggregateLLVMType(T)) {
    llvm::Value *V = EmitScalarExpr(Init);
    EmitStoreOfScalar(V, DeclPtr, T.isVolatileQualified(), T);
  } else if (T->isAnyComplexType()) {
    EmitComplexExprIntoAddr(Init, DeclPtr, T.isVolatileQualified());
  } else {
    EmitAggExpr(Init, DeclPtr, T.isVolatileQualified());
    
    if (const RecordType *RT = T->getAs<RecordType>()) {
      CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
      if (!RD->hasTrivialDestructor())
        EmitCXXGlobalDtorRegistration(RD->getDestructor(getContext()), DeclPtr);
    }
  }
}

void 
CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D, 
                                               llvm::GlobalVariable *GV) {
  // FIXME: This should use __cxa_guard_{acquire,release}?

  assert(!getContext().getLangOptions().ThreadsafeStatics &&
         "thread safe statics are currently not supported!");

  llvm::SmallString<256> GuardVName;
  llvm::raw_svector_ostream GuardVOut(GuardVName);
  mangleGuardVariable(&D, getContext(), GuardVOut);
  
  // Create the guard variable.
  llvm::GlobalValue *GuardV = 
    new llvm::GlobalVariable(CGM.getModule(), llvm::Type::Int64Ty, false,
                             GV->getLinkage(),
                             llvm::Constant::getNullValue(llvm::Type::Int64Ty),
                             GuardVName.c_str());
  
  // Load the first byte of the guard variable.
  const llvm::Type *PtrTy = llvm::PointerType::get(llvm::Type::Int8Ty, 0);
  llvm::Value *V = Builder.CreateLoad(Builder.CreateBitCast(GuardV, PtrTy), 
                                      "tmp");
  
  // Compare it against 0.
  llvm::Value *nullValue = llvm::Constant::getNullValue(llvm::Type::Int8Ty);
  llvm::Value *ICmp = Builder.CreateICmpEQ(V, nullValue , "tobool");
  
  llvm::BasicBlock *InitBlock = createBasicBlock("init");
  llvm::BasicBlock *EndBlock = createBasicBlock("init.end");

  // If the guard variable is 0, jump to the initializer code.
  Builder.CreateCondBr(ICmp, InitBlock, EndBlock);
                         
  EmitBlock(InitBlock