X86ISelLowering.cpp

//===-- X86ISelLowering.cpp - X86 DAG Lowering Implementation -------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the interfaces that X86 uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "x86-isel"
#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86ISelLowering.h"
#include "X86TargetMachine.h"
#include "X86TargetObjectFile.h"
#include "Utils/X86ShuffleDecode.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalAlias.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/LLVMContext.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/VectorExtras.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace dwarf;

STATISTIC(NumTailCalls, "Number of tail calls");

// Forward declarations.
static SDValue getMOVL(SelectionDAG &DAG, DebugLoc dl, EVT VT, SDValue V1,
                       SDValue V2);

static SDValue Insert128BitVector(SDValue Result,
                                  SDValue Vec,
                                  SDValue Idx,
                                  SelectionDAG &DAG,
                                  DebugLoc dl);

static SDValue Extract128BitVector(SDValue Vec,
                                   SDValue Idx,
                                   SelectionDAG &DAG,
                                   DebugLoc dl);

static SDValue ConcatVectors(SDValue Lower, SDValue Upper, SelectionDAG &DAG);


/// Generate a DAG to grab 128-bits from a vector > 128 bits.  This
/// sets things up to match to an AVX VEXTRACTF128 instruction or a
/// simple subregister reference.  Idx is an index in the 128 bits we
/// want.  It need not be aligned to a 128-bit bounday.  That makes
/// lowering EXTRACT_VECTOR_ELT operations easier.
static SDValue Extract128BitVector(SDValue Vec,
                                   SDValue Idx,
                                   SelectionDAG &DAG,
                                   DebugLoc dl) {
  EVT VT = Vec.getValueType();
  assert(VT.getSizeInBits() == 256 && "Unexpected vector size!");

  EVT ElVT = VT.getVectorElementType();

  int Factor = VT.getSizeInBits() / 128;

  EVT ResultVT = EVT::getVectorVT(*DAG.getContext(),
                                  ElVT,
                                  VT.getVectorNumElements() / Factor);

  // Extract from UNDEF is UNDEF.
  if (Vec.getOpcode() == ISD::UNDEF)
    return DAG.getNode(ISD::UNDEF, dl, ResultVT);

  if (isa<ConstantSDNode>(Idx)) {
    unsigned IdxVal = cast<ConstantSDNode>(Idx)->getZExtValue();

    // Extract the relevant 128 bits.  Generate an EXTRACT_SUBVECTOR
    // we can match to VEXTRACTF128.
    unsigned ElemsPerChunk = 128 / ElVT.getSizeInBits();

    // This is the index of the first element of the 128-bit chunk
    // we want.
    unsigned NormalizedIdxVal = (((IdxVal * ElVT.getSizeInBits()) / 128)
                                 * ElemsPerChunk);

    SDValue VecIdx = DAG.getConstant(NormalizedIdxVal, MVT::i32);

    SDValue Result = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, ResultVT, Vec,
                                 VecIdx);

    return Result;
  }

  return SDValue();
}

/// Generate a DAG to put 128-bits into a vector > 128 bits.  This
/// sets things up to match to an AVX VINSERTF128 instruction or a
/// simple superregister reference.  Idx is an index in the 128 bits
/// we want.  It need not be aligned to a 128-bit bounday.  That makes
/// lowering INSERT_VECTOR_ELT operations easier.
static SDValue Insert128BitVector(SDValue Result,
                                  SDValue Vec,
                                  SDValue Idx,
                                  SelectionDAG &DAG,
                                  DebugLoc dl) {
  if (isa<ConstantSDNode>(Idx)) {
    EVT VT = Vec.getValueType();
    assert(VT.getSizeInBits() == 128 && "Unexpected vector size!");

    EVT ElVT = VT.getVectorElementType();

    unsigned IdxVal = cast<ConstantSDNode>(Idx)->getZExtValue();

    EVT ResultVT = Result.getValueType();

    // Insert the relevant 128 bits.
    unsigned ElemsPerChunk = 128 / ElVT.getSizeInBits();

    // This is the index of the first element of the 128-bit chunk
    // we want.
    unsigned NormalizedIdxVal = (((IdxVal * ElVT.getSizeInBits()) / 128)
                                 * ElemsPerChunk);

    SDValue VecIdx = DAG.getConstant(NormalizedIdxVal, MVT::i32);

    Result = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResultVT, Result, Vec,
                         VecIdx);
    return Result;
  }

  return SDValue();
}

/// Given two vectors, concat them.
static SDValue ConcatVectors(SDValue Lower, SDValue Upper, SelectionDAG &DAG) {
  DebugLoc dl = Lower.getDebugLoc();

  assert(Lower.getValueType() == Upper.getValueType() && "Mismatched vectors!");

  EVT VT = EVT::getVectorVT(*DAG.getContext(),
                            Lower.getValueType().getVectorElementType(),
                            Lower.getValueType().getVectorNumElements() * 2);

  // TODO: Generalize to arbitrary vector length (this assumes 256-bit vectors).
  assert(VT.getSizeInBits() == 256 && "Unsupported vector concat!");

  // Insert the upper subvector.
  SDValue Vec = Insert128BitVector(DAG.getNode(ISD::UNDEF, dl, VT), Upper,
                                   DAG.getConstant(
                                     // This is half the length of the result
                                     // vector.  Start inserting the upper 128
                                     // bits here.
                                     Lower.getValueType().getVectorNumElements(),
                                     MVT::i32),
                                   DAG, dl);

  // Insert the lower subvector.
  Vec = Insert128BitVector(Vec, Lower, DAG.getConstant(0, MVT::i32), DAG, dl);
  return Vec;
}

static TargetLoweringObjectFile *createTLOF(X86TargetMachine &TM) {
  const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
  bool is64Bit = Subtarget->is64Bit();

  if (Subtarget->isTargetEnvMacho()) {
    if (is64Bit)
      return new X8664_MachoTargetObjectFile();
    return new TargetLoweringObjectFileMachO();
  }

  if (Subtarget->isTargetELF()) {