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/Basic/TargetBuiltins.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
using namespace llvm;

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

/// Utility to insert an atomic instruction based Instrinsic::ID and
// the expression node, where the return value is the result of the
// operation.
static RValue EmitBinaryAtomicPost(CodeGenFunction& CGF,
                                   Intrinsic::ID Id, const CallExpr *E,
                                   Instruction::BinaryOps Op) {
  const llvm::Type *ResType[2];
  ResType[0] = CGF.ConvertType(E->getType());
  ResType[1] = CGF.ConvertType(E->getArg(0)->getType());
  Value *AtomF = CGF.CGM.getIntrinsic(Id, ResType, 2);
  Value *Ptr = CGF.EmitScalarExpr(E->getArg(0));
  Value *Operand = CGF.EmitScalarExpr(E->getArg(1));
  Value *Result = CGF.Builder.CreateCall2(AtomF, Ptr, Operand);

  if (Id == Intrinsic::atomic_load_nand)
    Result = CGF.Builder.CreateNot(Result);


  return RValue::get(CGF.Builder.CreateBinOp(Op, Result, Operand));
}

RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
                                        unsigned BuiltinID, const CallExpr *E) {
  // See if we can constant fold this builtin.  If so, don't emit it at all.
  Expr::EvalResult Result;
  if (E->Evaluate(Result, CGM.getContext())) {
    if (Result.Val.isInt())
      return RValue::get(llvm::ConstantInt::get(VMContext,
                                                Result.Val.getInt()));
    else if (Result.Val.isFloat())
      return RValue::get(ConstantFP::get(VMContext, Result.Val.getFloat()));
  }

  switch (BuiltinID) {
  default: break;  // Handle intrinsics and libm functions below.
  case Builtin::BI__builtin___CFStringMakeConstantString:
  case Builtin::BI__builtin___NSStringMakeConstantString:
    return RValue::get(CGM.EmitConstantExpr(E, E->getType(), 0));
  case Builtin::BI__builtin_stdarg_start:
  case Builtin::BI__builtin_va_start:
  case Builtin::BI__builtin_va_end: {
    Value *ArgValue = EmitVAListRef(E->getArg(0));
    const llvm::Type *DestType = llvm::Type::getInt8PtrTy(VMContext);
    if (ArgValue->getType() != DestType)
      ArgValue = Builder.CreateBitCast(ArgValue, DestType,
                                       ArgValue->getName().data());

    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: {
    Value *DstPtr = EmitVAListRef(E->getArg(0));
    Value *SrcPtr = EmitVAListRef(E->getArg(1));

    const llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext);

    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,
                          llvm::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