lib/CodeGen/CGTemporaries.cpp

//===--- CGTemporaries.cpp - Emit LLVM Code for C++ temporaries -----------===//
//
//                     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 of temporaries
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
using namespace clang;
using namespace CodeGen;

static void EmitTemporaryCleanup(CodeGenFunction &CGF,
                                 const CXXTemporary *Temporary,
                                 llvm::Value *Addr,
                                 llvm::Value *CondPtr) {
  llvm::BasicBlock *CondEnd = 0;
    
  // If this is a conditional temporary, we need to check the condition
  // boolean and only call the destructor if it's true.
  if (CondPtr) {
    llvm::BasicBlock *CondBlock = CGF.createBasicBlock("temp.cond-dtor.call");
    CondEnd = CGF.createBasicBlock("temp.cond-dtor.cont");

    llvm::Value *Cond = CGF.Builder.CreateLoad(CondPtr);
    CGF.Builder.CreateCondBr(Cond, CondBlock, CondEnd);
    CGF.EmitBlock(CondBlock);
  }

  CGF.EmitCXXDestructorCall(Temporary->getDestructor(),
                            Dtor_Complete, /*ForVirtualBase=*/false,
                            Addr);

  if (CondPtr) {
    // Reset the condition to false.
    CGF.Builder.CreateStore(llvm::ConstantInt::getFalse(CGF.getLLVMContext()),
                            CondPtr);
    CGF.EmitBlock(CondEnd);
  }
}                                 

/// Emits all the code to cause the given temporary to be cleaned up.
void CodeGenFunction::EmitCXXTemporary(const CXXTemporary *Temporary,
                                       llvm::Value *Ptr) {
  llvm::AllocaInst *CondPtr = 0;

  // Check if temporaries need to be conditional. If so, we'll create a
  // condition boolean, initialize it to 0 and
  if (ConditionalBranchLevel != 0) {
    CondPtr = CreateTempAlloca(llvm::Type::getInt1Ty(VMContext), "cond");

    // Initialize it to false. This initialization takes place right after
    // the alloca insert point.
    InitTempAlloca(CondPtr, llvm::ConstantInt::getFalse(VMContext));

    // Now set it to true.
    Builder.CreateStore(llvm::ConstantInt::getTrue(VMContext), CondPtr);
  }

  CleanupBlock Cleanup(*this, NormalCleanup);
  EmitTemporaryCleanup(*this, Temporary, Ptr, CondPtr);

  if (Exceptions) {
    Cleanup.beginEHCleanup();
    EmitTemporaryCleanup(*this, Temporary, Ptr, CondPtr);
  }
}

RValue
CodeGenFunction::EmitCXXExprWithTemporaries(const CXXExprWithTemporaries *E,
                                            llvm::Value *AggLoc,
                                            bool IsAggLocVolatile,
                                            bool IsInitializer) {
  RValue RV;
  {
    RunCleanupsScope Scope(*this);

    RV = EmitAnyExpr(E->getSubExpr(), AggLoc, IsAggLocVolatile,
                     /*IgnoreResult=*/false, IsInitializer);
  }
  return RV;
}

LValue CodeGenFunction::EmitCXXExprWithTemporariesLValue(
                                              const CXXExprWithTemporaries *E) {
  LValue LV;
  {
    RunCleanupsScope Scope(*this);

    LV = EmitLValue(E->getSubExpr());
  }
  return LV;
}