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/ASTContext.h"
#include "clang/AST/Builtins.h"
#include "clang/AST/Expr.h"
#include "clang/AST/TargetBuiltins.h"
#include "llvm/Constants.h"
#include "llvm/Function.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 = CFG.ConvertType(E->getType());
  Value *AtomF = CFG.CGM.getIntrinsic(Id, &ResType, 1);
  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) {
  switch (BuiltinID) {
  default: {
    if (getContext().BuiltinInfo.isLibFunction(BuiltinID))
      return EmitCallExpr(CGM.getBuiltinLibFunction(BuiltinID), 
                          E->getCallee()->getType(), E->arg_begin(),
                          E->getNumArgs());
  
    // See if we have a target specific intrinsic.
    Intrinsic::ID IntrinsicID;
    const char *TargetPrefix = Target.getTargetPrefix();
    const char *BuiltinName = getContext().BuiltinInfo.GetName(BuiltinID);
#define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
#include "llvm/Intrinsics.gen"
#undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
    
    if (IntrinsicID != Intrinsic::not_intrinsic) {
      SmallVector<Value*, 16> Args;
      
      Function *F = CGM.getIntrinsic(IntrinsicID);
      const llvm::FunctionType *FTy = F->getFunctionType();
      
      for (unsigned i = 0, e = E->getNumArgs(); i != e; ++i) {
        Value *ArgValue = EmitScalarExpr(E->getArg(i));
  
        // If the intrinsic arg type is different from the builtin arg type
        // we need to do a bit cast.
        const llvm::Type *PTy = FTy->getParamType(i);
        if (PTy != ArgValue->getType()) {
          assert(PTy->canLosslesslyBitCastTo(FTy->getParamType(i)) &&
                 "Must be able to losslessly bit cast to param");
          ArgValue = Builder.CreateBitCast(ArgValue, PTy);
        }

        Args.push_back(ArgValue);
      }
            
      Value *V = Builder.CreateCall(F, &Args[0], &Args[0] + Args.size());
      QualType BuiltinRetType = E->getType();
      
      const llvm::Type *RetTy = llvm::Type::VoidTy;
      if (!BuiltinRetType->isVoidType()) RetTy = ConvertType(BuiltinRetType);

      if (RetTy != V->getType()) {
        assert(V->getType()->canLosslesslyBitCastTo(RetTy) &&
               "Must be able to losslessly bit cast result type");
        V = Builder.CreateBitCast(V, RetTy);
      }
      
      return RValue::get(V);
    }

    // See if we have a target specific builtin that needs to be lowered.
    Value *V = 0;
    
    if (strcmp(TargetPrefix, "x86") == 0)
      V = EmitX86BuiltinExpr(BuiltinID, E);
    else if (strcmp(TargetPrefix, "ppc") == 0)
      V = EmitPPCBuiltinExpr(BuiltinID, E);

    if (V)
      return RValue::get(V);
    
    WarnUnsupported(E, "builtin function");

    // Unknown builtin, for now just dump it out and return undef.
    if (hasAggregateLLVMType(E->getType()))
      return RValue::getAggregate(CreateTempAlloca(ConvertType(E->getType())));
    return RValue::get(UndefValue::get(ConvertType(E->getType())));
  }    
  case Builtin::BI__builtin___CFStringMakeConstantString: {
    const Expr *Arg = E->getArg(0);
    
    while (1) {
      if (const ParenExpr *PE = dyn_cast<ParenExpr>(Arg))
        Arg = PE->getSubExpr();
      else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Arg))
        Arg = CE->getSubExpr();
      else
        break;
    }
    
    const StringLiteral *Literal = cast<StringLiteral>(Arg);
    std::string S(Literal->getStrData(), Literal->getByteLength());
    
    return RValue::get(CGM.GetAddrOfConstantCFString(S));
  }
  case Builtin::BI__builtin_va_start:
  case Builtin::BI__builtin_va_end: {
    Value *ArgValue = EmitScalarExpr(E->getArg(0));
    const llvm::Type *DestType = 
      llvm