path: root/lib/CodeGen/CGBuiltin.cpp

//===---- CGBuiltin.cpp - Emit LLVM Code for builtins ---------------------===//
//
//                     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 Builtin calls as LLVM code.
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/TargetBuiltins.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
using namespace llvm;

/// Utility to insert an atomic instruction based Instrinsic::ID and
// the expression node
static RValue EmitBinaryAtomic(CodeGenFunction& CFG, 
                               Intrinsic::ID Id, const CallExpr *E) {
  const llvm::Type *ResType[2];
  ResType[0] = CFG.ConvertType(E->getType());
  ResType[1] = CFG.ConvertType(E->getArg(0)->getType());
  Value *AtomF = CFG.CGM.getIntrinsic(Id, ResType, 2);
  return RValue::get(CFG.Builder.CreateCall2(AtomF,
                                             CFG.EmitScalarExpr(E->getArg(0)),
                                             CFG.EmitScalarExpr(E->getArg(1))));
}

RValue CodeGenFunction::EmitBuiltinExpr(unsigned BuiltinID, const CallExpr *E) {
  // See if we can constant fold this builtin.  If so, don't emit it at all.
  APValue Result;
  if (E->Evaluate(Result, CGM.getContext())) {
    if (Result.isInt())
      return RValue::get(llvm::ConstantInt::get(Result.getInt()));
    assert(Result.isFloat() && "Unsupported constant type");
    return RValue::get(llvm::ConstantFP::get(Result.getFloat()));
  }
      
  switch (BuiltinID) {
  default: break;  // Handle intrinsics and libm functions below.
  case Builtin::BI__builtin___CFStringMakeConstantString:
    return RValue::get(CGM.EmitConstantExpr(E, 0));
  case Builtin::BI__builtin_stdarg_start:
  case Builtin::BI__builtin_va_start:
  case Builtin::BI__builtin_va_end: {
    Value *ArgValue = EmitLValue(E->getArg(0)).getAddress();
    const llvm::Type *DestType = 
      llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
    if (ArgValue->getType() != DestType)
      ArgValue = Builder.CreateBitCast(ArgValue, DestType, 
                                       ArgValue->getNameStart());

    Intrinsic::ID inst = (BuiltinID == Builtin::BI__builtin_va_end) ? 
      Intrinsic::vaend : Intrinsic::vastart;
    return RValue::get(Builder.CreateCall(CGM.getIntrinsic(inst), ArgValue));
  }
  case Builtin::BI__builtin_va_copy: {
    // FIXME: This does not yet handle architectures where va_list is a struct.
    Value *DstPtr = EmitLValue(E->getArg(0)).getAddress();
    Value *SrcValue = EmitScalarExpr(E->getArg(1));
    
    Value *SrcPtr = CreateTempAlloca(SrcValue->getType(), "dst_ptr");
    
    Builder.CreateStore(SrcValue, SrcPtr, false);

    const llvm::Type *Type = 
      llvm::PointerType::getUnqual(llvm::Type::Int8Ty);

    DstPtr = Builder.CreateBitCast(DstPtr, Type);
    SrcPtr = Builder.CreateBitCast(SrcPtr, Type);
    return RValue::get(Builder.CreateCall2(CGM.getIntrinsic(Intrinsic::vacopy), 
                                           DstPtr, SrcPtr));
  }
  case Builtin::BI__builtin_abs: {
    Value *ArgValue = EmitScalarExpr(E->getArg(0));   
    
    Value *NegOp = Builder.CreateNeg(ArgValue, "neg");
    Value *CmpResult = 
    Builder.CreateICmpSGE(ArgValue, Constant::getNullValue(ArgValue->getType()),
                                                            "abscond");
    Value *Result = 
      Builder.CreateSelect(CmpResult, ArgValue, NegOp, "abs");
    
    return RValue::get(Result);
  }
  case Builtin::BI__builtin_ctz:
  case Builtin::BI__builtin_ctzl:
  case Builtin::BI__builtin_ctzll: {
    Value *ArgValue = EmitScalarExpr(E->getArg(0));
    
    const llvm::Type *ArgType = ArgValue->getType();
    Value *F = CGM.getIntrinsic(Intrinsic::cttz, &ArgType, 1);

    const llvm::Type *ResultType = ConvertType(E->getType());    
    Value *Result = Builder.CreateCall(F, ArgValue, "tmp");
    if