path: root/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

//===-------- LegalizeFloatTypes.cpp - Legalization of float types --------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements float type expansion and softening for LegalizeTypes.
// Softening is the act of turning a computation in an illegal floating point
// type into a computation in an integer type of the same size; also known as
// "soft float".  For example, turning f32 arithmetic into operations using i32.
// The resulting integer value is the same as what you would get by performing
// the floating point operation and bitcasting the result to the integer type.
// Expansion is the act of changing a computation in an illegal type to be a
// computation in two identical registers of a smaller type.  For example,
// implementing ppcf128 arithmetic in two f64 registers.
//
//===----------------------------------------------------------------------===//

#include "LegalizeTypes.h"
using namespace llvm;

/// GetFPLibCall - Return the right libcall for the given floating point type.
static RTLIB::Libcall GetFPLibCall(MVT VT,
                                   RTLIB::Libcall Call_F32,
                                   RTLIB::Libcall Call_F64,
                                   RTLIB::Libcall Call_F80,
                                   RTLIB::Libcall Call_PPCF128) {
  return
    VT == MVT::f32 ? Call_F32 :
    VT == MVT::f64 ? Call_F64 :
    VT == MVT::f80 ? Call_F80 :
    VT == MVT::ppcf128 ? Call_PPCF128 :
    RTLIB::UNKNOWN_LIBCALL;
}

//===----------------------------------------------------------------------===//
//  Result Float to Integer Conversion.
//===----------------------------------------------------------------------===//

void DAGTypeLegalizer::SoftenFloatResult(SDNode *N, unsigned ResNo) {
  DEBUG(cerr << "Soften float result " << ResNo << ": "; N->dump(&DAG);
        cerr << "\n");
  SDOperand R = SDOperand();

  switch (N->getOpcode()) {
  default:
#ifndef NDEBUG
    cerr << "SoftenFloatResult #" << ResNo << ": ";
    N->dump(&DAG); cerr << "\n";
#endif
    assert(0 && "Do not know how to soften the result of this operator!");
    abort();

    case ISD::BIT_CONVERT: R = SoftenFloatRes_BIT_CONVERT(N); break;
    case ISD::BUILD_PAIR:  R = SoftenFloatRes_BUILD_PAIR(N); break;
    case ISD::ConstantFP:
      R = SoftenFloatRes_ConstantFP(cast<ConstantFPSDNode>(N));
      break;
    case ISD::FADD:        R = SoftenFloatRes_FADD(N); break;
    case ISD::FCOPYSIGN:   R = SoftenFloatRes_FCOPYSIGN(N); break;
    case ISD::FDIV:        R = SoftenFloatRes_FDIV(N); break;
    case ISD::FMUL:        R = SoftenFloatRes_FMUL(N); break;
    case ISD::FP_EXTEND:   R = SoftenFloatRes_FP_EXTEND(N); break;
    case ISD::FP_ROUND:    R = SoftenFloatRes_FP_ROUND(N); break;
    case ISD::FPOWI:       R = SoftenFloatRes_FPOWI(N); break;
    case ISD::FSUB:        R = SoftenFloatRes_FSUB(N); break;
    case ISD::LOAD:        R = SoftenFloatRes_LOAD(N); break;
    case ISD::SELECT:      R = SoftenFloatRes_SELECT(N); break;
    case ISD::SELECT_CC:   R = SoftenFloatRes_SELECT_CC(N); break;
    case ISD::SINT_TO_FP:  R = SoftenFloatRes_SINT_TO_FP(N); break;
    case ISD::UINT_TO_FP:  R = SoftenFloatRes_UINT_TO_FP(N); break;
  }

  // If R is null, the sub-method took care of registering the result.
  if (R.Val)
    SetSoftenedFloat(SDOperand(N, ResNo), R);
}

SDOperand DAGTypeLegalizer::SoftenFloatRes_BIT_CONVERT(SDNode *N) {
  return BitConvertToInteger(N->getOperand(0));
}

SDOperand DAGTypeLegalizer::SoftenFloatRes_BUILD_PAIR(SDNode *N) {
  // Convert the inputs to integers, and build a new pair out of them.
  return DAG.getNode(ISD::BUILD_PAIR,
                     TLI.getTypeToTransformTo(N->getValueType(0)),
                     BitConvertToInteger(N->getOperand(0)),
                     BitConvertToInteger(N->getOperand(1)));
}

SDOperand DAGTypeLegalizer::SoftenFloatRes_ConstantFP(ConstantFPSDNode *N) {
  return DAG.getConstant(N->getValueAPF().convertToAPInt(),
                         TLI.getTypeToTransformTo(N->getValueType(0)));
}

SDOperand DAGTypeLegalizer::SoftenFloatRes_FADD(SDNode *N) {
  MVT NVT = TLI.getTypeToTransformTo(N->getValueType(0));
  SDOperand Ops[2] = { GetSoftenedFloat(N->getOperand(0)),
                       GetSoftenedFloat(N->getOperand(1)) };
  return MakeLibCall(GetFPLibCall(N->getValueType(0),
                                  RTLIB::ADD_F32,
                                  RTLIB::ADD_F64,
                                  RTLIB::ADD_F80,
                                  RTLIB::ADD_PPCF128),
                     NVT, Ops, 2