path: root/lib/CodeGen/CGExpr.cpp

//===--- CGExpr.cpp - Emit LLVM Code from Expressions ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Expr nodes as LLVM code.
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "CGCall.h"
#include "CGObjCRuntime.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/Target/TargetData.h"
using namespace clang;
using namespace CodeGen;

//===--------------------------------------------------------------------===//
//                        Miscellaneous Helper Methods
//===--------------------------------------------------------------------===//

/// CreateTempAlloca - This creates a alloca and inserts it into the entry
/// block.
llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(const llvm::Type *Ty,
                                                    const char *Name) {
  return new llvm::AllocaInst(Ty, 0, Name, AllocaInsertPt);
}

/// EvaluateExprAsBool - Perform the usual unary conversions on the specified
/// expression and compare the result against zero, returning an Int1Ty value.
llvm::Value *CodeGenFunction::EvaluateExprAsBool(const Expr *E) {
  QualType BoolTy = getContext().BoolTy;
  if (!E->getType()->isAnyComplexType())
    return EmitScalarConversion(EmitScalarExpr(E), E->getType(), BoolTy);

  return EmitComplexToScalarConversion(EmitComplexExpr(E), E->getType(),BoolTy);
}

/// EmitAnyExpr - Emit code to compute the specified expression which can have
/// any type.  The result is returned as an RValue struct.  If this is an
/// aggregate expression, the aggloc/agglocvolatile arguments indicate where
/// the result should be returned.
RValue CodeGenFunction::EmitAnyExpr(const Expr *E, llvm::Value *AggLoc, 
                                    bool isAggLocVolatile) {
  if (!hasAggregateLLVMType(E->getType()))
    return RValue::get(EmitScalarExpr(E));
  else if (E->getType()->isAnyComplexType())
    return RValue::getComplex(EmitComplexExpr(E));
  
  EmitAggExpr(E, AggLoc, isAggLocVolatile);
  return RValue::getAggregate(AggLoc);
}

/// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result
/// will always be accessible even if no aggregate location is
/// provided.
RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E, llvm::Value *AggLoc, 
                                          bool isAggLocVolatile) {
  if (!AggLoc && hasAggregateLLVMType(E->getType()) && 
      !E->getType()->isAnyComplexType())
    AggLoc = CreateTempAlloca(ConvertType(E->getType()), "agg.tmp");
  return EmitAnyExpr(E, AggLoc, isAggLocVolatile);
}

/// getAccessedFieldNo - Given an encoded value and a result number, return
/// the input field number being accessed.
unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx, 
                                             const llvm::Constant *Elts) {
  if (isa<llvm::ConstantAggregateZero>(Elts))
    return 0;
  
  return cast<llvm::ConstantInt>(Elts->getOperand(Idx))->getZExtValue();
}


//===----------------------------------------------------------------------===//
//                         LValue Expression Emission
//===----------------------------------------------------------------------===//

LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
                                              const char *Name) {
  ErrorUnsupported(E, Name);
  llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
  return LValue::MakeAddr(llvm::UndefValue::get(Ty),
                          E->getType().getCVRQualifiers());
}

/// EmitLValue - Emit code to compute a designator that specifies the location
/// of the expression.
///
/// This can return one of two things: a simple address or a bitfield
/// reference.  In either case, the LLVM Value* in the LValue structure is
/// guaranteed to be an LLVM pointer type.
///
/// If this returns a bitfield reference, nothing about the pointee type of
/// the LLVM value is known: For example, it may not be a pointer to an
/// integer.
///
/// If this returns a normal address, and if the lvalue's C type is fixed
/// size, this method guarantees that the returned pointer type will point to
/// an LLVM type of the same size of the lvalue's type.  If the lvalue has a
/// variable length type, this is not possible.
///
LValue CodeGenFunction::EmitLValue(const Expr *E) {
  switch (E->getStmtClass()) {
  default: return EmitUnsupportedLValue(E, "l-value expression");

  case Expr::BinaryOperatorClass: 
    return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
  case Expr::CallExprClass: 
  case Expr::CXXOperatorCallExprClass:
    return EmitCallExprLValue(cast<CallExpr>(E));
  case Expr::DeclRefExprClass: return EmitDeclRefLValue(cast<DeclRefExpr>(E));
  case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
  case Expr::PredefinedExprClass:
    return EmitPredefinedLValue(cast<PredefinedExpr>(E));
  case Expr::StringLiteralClass:
    return EmitStringLiteralLValue(cast<StringLiteral>(E));

  case Expr::CXXConditionDeclExprClass:
    return EmitCXXConditionDeclLValue(cast<CXXConditionDeclExpr>(E));

  case Expr::ObjCMessageExprClass: