X86ISelLowering.cpp

}

/// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
/// vector.  If it is invalid, don't add anything to Ops.
void X86TargetLowering::LowerAsmOperandForConstraint(SDValue Op,
                                                     char Constraint,
                                                     bool hasMemory,
                                                     std::vector<SDValue>&Ops,
                                                     SelectionDAG &DAG) const {
  SDValue Result(0, 0);

  switch (Constraint) {
  default: break;
  case 'I':
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      if (C->getZExtValue() <= 31) {
        Result = DAG.getTargetConstant(C->getZExtValue(), Op.getValueType());
        break;
      }
    }
    return;
  case 'J':
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      if (C->getZExtValue() <= 63) {
        Result = DAG.getTargetConstant(C->getZExtValue(), Op.getValueType());
        break;
      }
    }
    return;
  case 'K':
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      if ((int8_t)C->getSExtValue() == C->getSExtValue()) {
        Result = DAG.getTargetConstant(C->getZExtValue(), Op.getValueType());
        break;
      }
    }
    return;
  case 'N':
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      if (C->getZExtValue() <= 255) {
        Result = DAG.getTargetConstant(C->getZExtValue(), Op.getValueType());
        break;
      }
    }
    return;
  case 'e': {
    // 32-bit signed value
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      const ConstantInt *CI = C->getConstantIntValue();
      if (CI->isValueValidForType(Type::getInt32Ty(*DAG.getContext()),
                                  C->getSExtValue())) {
        // Widen to 64 bits here to get it sign extended.
        Result = DAG.getTargetConstant(C->getSExtValue(), MVT::i64);
        break;
      }
    // FIXME gcc accepts some relocatable values here too, but only in certain
    // memory models; it's complicated.
    }
    return;
  }
  case 'Z': {
    // 32-bit unsigned value
    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
      const ConstantInt *CI = C->getConstantIntValue();
      if (CI->isValueValidForType(Type::getInt32Ty(*DAG.getContext()),
                                  C->getZExtValue())) {
        Result = DAG.getTargetConstant(C->getZExtValue(), Op.getValueType());
        break;
      }
    }
    // FIXME gcc accepts some relocatable values here too, but only in certain
    // memory models; it's complicated.
    return;
  }
  case 'i': {
    // Literal immediates are always ok.
    if (ConstantSDNode *CST = dyn_cast<ConstantSDNode>(Op)) {
      // Widen to 64 bits here to get it sign extended.
      Result = DAG.getTargetConstant(CST->getSExtValue(), MVT::i64);
      break;
    }

    // If we are in non-pic codegen mode, we allow the address of a global (with
    // an optional displacement) to be used with 'i'.
    GlobalAddressSDNode *GA = 0;
    int64_t Offset = 0;

    // Match either (GA), (GA+C), (GA+C1+C2), etc.
    while (1) {
      if ((GA = dyn_cast<GlobalAddressSDNode>(Op))) {
        Offset += GA->getOffset();
        break;
      } else if (Op.getOpcode() == ISD::ADD) {
        if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
          Offset += C->getZExtValue();
          Op = Op.getOperand(0);
          continue;
        }
      } else if (Op.getOpcode() == ISD::SUB) {
        if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
          Offset += -C->getZExtValue();
          Op = Op.getOperand(0);
          continue;
        }
      }

      // Otherwise, this isn't something we can handle, reject it.
      return;
    }

    GlobalValue *GV = GA->getGlobal();
    // If we require an extra load to get this address, as in PIC mode, we
    // can't accept it.
    if (isGlobalStubReference(Subtarget->ClassifyGlobalReference(GV,
                                                        getTargetMachine())))
      return;

    if (hasMemory)
      Op = LowerGlobalAddress(GV, Op.getDebugLoc(), Offset, DAG);
    else
      Op = DAG.getTargetGlobalAddress(GV, GA->getValueType(0), Offset);
    Result = Op;
    break;
  }
  }

  if (Result.getNode()) {
    Ops.push_back(Result);
    return;
  }
  return TargetLowering::LowerAsmOperandForConstraint(Op, Constraint, hasMemory,
                                                      Ops, DAG);
}

std::vector<unsigned> X86TargetLowering::
getRegClassForInlineAsmConstraint(const std::string &Constraint,
                                  EVT VT) const {
  if (Constraint.size() == 1) {
    // FIXME: not handling fp-stack yet!
    switch (Constraint[0]) {      // GCC X86 Constraint Letters
    default: break;  // Unknown constraint letter
    case 'q':   // GENERAL_REGS in 64-bit mode, Q_REGS in 32-bit mode.
      if (Subtarget->is64Bit()) {
        if (VT == MVT::i32)
          return make_vector<unsigned>(X86::EAX, X86::EDX, X86::ECX, X86::EBX,
                                       X86::ESI, X86::EDI, X86::R8D, X86::R9D,
                                       X86::R10D,X86::R11D,X86::R12D,
                                       X86::R13D,X86::R14D,X86::R15D,
                                       X86::EBP, X86::ESP, 0);
        else if (VT == MVT::i16)
          return make_vector<unsigned>(X86::AX,  X86::DX,  X86::CX, X86::BX,
                                       X86::SI,  X86::DI,  X86::R8W,X86::R9W,
                                       X86::R10W,X86::R11W,X86::R12W,
                                       X86::R13W,X86::R14W,X86::R15W,
                                       X86::BP,  X86::SP, 0);
        else if (VT == MVT::i8)
          return make_vector<unsigned>(X86::AL,  X86::DL,  X86::CL, X86::BL,
                                       X86::SIL, X86::DIL, X86::R8B,X86::R9B,
                                       X86::R10B,X86::R11B,X86::R12B,
                                       X86::R13B,X86::R14B,X86::R15B,
                                       X86::BPL, X86::SPL, 0);

        else if (VT == MVT::i64)
          return make_vector<unsigned>(X86::RAX, X86::RDX, X86::RCX, X86::RBX,
                                       X86::RSI, X86::RDI, X86::R8,  X86::R9,
                                       X86::R10, X86::R11, X86::R12,
                                       X86::R13, X86::R14, X86::R15,
                                       X86::RBP, X86::RSP, 0);

        break;
      }
      // 32-bit fallthrough
    case 'Q':   // Q_REGS
      if (VT == MVT::i32)
        return make_vector<unsigned>(X86::EAX, X86::EDX, X86::ECX, X86::EBX, 0);
      else if (VT == MVT::i16)
        return make_vector<unsigned>(X86::AX, X86::DX, X86::CX, X86::BX, 0);
      else if (VT == MVT::i8)
        return make_vector<unsigned>(X86::AL, X86::DL, X86::CL, X86::BL, 0);
      else if (VT == MVT::i64)
        return make_vector<unsigned>(X86::RAX, X86::RDX, X86::RCX, X86::RBX, 0);
      break;
    }
  }

  return std::vector<unsigned>();
}

std::pair<unsigned, const TargetRegisterClass*>
X86TargetLowering::getRegForInlineAsmConstraint(const std::string &Constraint,
                                                EVT VT) const {
  // First, see if this is a constraint that directly corresponds to an LLVM
  // register class.
  if (Constraint.size() == 1) {
    // GCC Constraint Letters
    switch (Constraint[0]) {
    default: break;
    case 'r':   // GENERAL_REGS
    case 'l':   // INDEX_REGS
      if (VT == MVT::i8)
        return std::make_pair(0U, X86::GR8RegisterClass);
      if (VT == MVT::i16)
        return std::make_pair(0U, X86::GR16RegisterClass);
      if (VT == MVT::i32 || !Subtarget->is64Bit())
        return std::make_pair(0U, X86::GR32RegisterClass);
      return std::make_pair(0U, X86::GR64RegisterClass);
    case 'R':   // LEGACY_REGS
      if (VT == MVT::i8)
        return std::make_pair(0U, X86::GR8_NOREXRegisterClass);
      if (VT == MVT::i16)
        return std::make_pair(0U, X86::GR16_NOREXRegisterClass);
      if (VT == MVT::i32 || !Subtarget->is64Bit())
        return std::make_pair(0U, X86::GR32_NOREXRegisterClass);
      return std::make_pair(0U, X86::GR64_NOREXRegisterClass);
    case 'f':  // FP Stack registers.
      // If SSE is enabled for this VT, use f80 to ensure the isel moves the
      // value to the correct fpstack register class.
      if (VT == MVT::f32 && !isScalarFPTypeInSSEReg(VT))
        return std::make_pair(0U, X86::RFP32RegisterClass);
      if (VT == MVT::f64 && !isScalarFPTypeInSSEReg(VT))
        return std::make_pair(0U, X86::RFP64RegisterClass);
      return std::make_pair(0U, X86::RFP80RegisterClass);
    case 'y':   // MMX_REGS if MMX allowed.
      if (!Subtarget->hasMMX()) break;
      return std::make_pair(0U, X86::VR64RegisterClass);
    case 'Y':   // SSE_REGS if SSE2 allowed
      if (!Subtarget->hasSSE2()) break;
      // FALL THROUGH.
    case 'x':   // SSE_REGS if SSE1 allowed
      if (!Subtarget->hasSSE1()) break;

      switch (VT.getSimpleVT().SimpleTy) {
      default: break;
      // Scalar SSE types.
      case MVT::f32:
      case MVT::i32:
        return std::make_pair(0U, X86::FR32RegisterClass);
      case MVT::f64:
      case MVT::i64:
        return std::make_pair(0U, X86::FR64RegisterClass);
      // Vector types.
      case MVT::v16i8:
      case MVT::v8i16:
      case MVT::v4i32:
      case MVT::v2i64:
      case MVT::v4f32:
      case MVT::v2f64:
        return std::make_pair(0U, X86::VR128RegisterClass);
      }
      break;
    }
  }

  // Use the default implementation in TargetLowering to convert the register
  // constraint into a member of a register class.
  std::pair<unsigned, const TargetRegisterClass*> Res;
  Res = TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);

  // Not found as a standard register?
  if (Res.second == 0) {
    // Map st(0) -> st(7) -> ST0
    if (Constraint.size() == 7 && Constraint[0] == '{' &&
        tolower(Constraint[1]) == 's' &&
        tolower(Constraint[2]) == 't' &&
        Constraint[3] == '(' &&
        (Constraint[4] >= '0' && Constraint[4] <= '7') &&
        Constraint[5] == ')' &&
        Constraint[6] == '}') {

      Res.first = X86::ST0+Constraint[4]-'0';
      Res.second = X86::RFP80RegisterClass;
      return Res;
    }

    // GCC allows "st(0)" to be called just plain "st".
    if (StringRef("{st}").equals_lower(Constraint)) {
      Res.first = X86::ST0;
      Res.second = X86::RFP80RegisterClass;
      return Res;
    }

    // flags -> EFLAGS
    if (StringRef("{flags}").equals_lower(Constraint)) {
      Res.first = X86::EFLAGS;
      Res.second = X86::CCRRegisterClass;
      return Res;
    }

    // 'A' means EAX + EDX.
    if (Constraint == "A") {
      Res.first = X86::EAX;
      Res.second = X86::GR32_ADRegisterClass;
      return Res;
    }
    return Res;
  }

  // Otherwise, check to see if this is a register class of the wrong value
  // type.  For example, we want to map "{ax},i32" -> {eax}, we don't want it to
  // turn into {ax},{dx}.
  if (Res.second->hasType(VT))
    return Res;   // Correct type already, nothing to do.

  // All of the single-register GCC register classes map their values onto
  // 16-bit register pieces "ax","dx","cx","bx","si","di","bp","sp".  If we
  // really want an 8-bit or 32-bit register, map to the appropriate register
  // class and return the appropriate register.
  if (Res.second == X86::GR16RegisterClass) {
    if (VT == MVT::i8) {
      unsigned DestReg = 0;
      switch (Res.first) {
      default: break;
      case X86::AX: DestReg = X86::AL; break;
      case X86::DX: DestReg = X86::DL; break;
      case X86::CX: DestReg = X86::CL; break;
      case X86::BX: DestReg = X86::BL; break;
      }
      if (DestReg) {
        Res.first = DestReg;
        Res.second = X86::GR8RegisterClass;
      }
    } else if (VT == MVT::i32) {
      unsigned DestReg = 0;
      switch (Res.first) {
      default: break;
      case X86::AX: DestReg = X86::EAX; break;
      case X86::DX: DestReg = X86::EDX; break;
      case X86::CX: DestReg = X86::ECX; break;
      case X86::BX: DestReg = X86::EBX; break;
      case X86::SI: DestReg = X86::ESI; break;
      case X86::DI: DestReg = X86::EDI; break;
      case X86::BP: DestReg = X86::EBP; break;
      case X86::SP: DestReg = X86::ESP; break;
      }
      if (DestReg) {
        Res.first = DestReg;
        Res.second = X86::GR32RegisterClass;
      }
    } else if (VT == MVT::i64) {
      unsigned DestReg = 0;
      switch (Res.first) {
      default: break;
      case X86::AX: DestReg = X86::RAX; break;
      case X86::DX: DestReg = X86::RDX; break;
      case X86::CX: DestReg = X86::RCX; break;
      case X86::BX: DestReg = X86::RBX; break;
      case X86::SI: DestReg = X86::RSI; break;
      case X86::DI: DestReg = X86::RDI; break;
      case X86::BP: DestReg = X86::RBP; break;
      case X86::SP: DestReg = X86::RSP; break;
      }
      if (DestReg) {
        Res.first = DestReg;
        Res.second = X86::GR64RegisterClass;
      }
    }
  } else if (Res.second == X86::FR32RegisterClass ||
             Res.second == X86::FR64RegisterClass ||
             Res.second == X86::VR128RegisterClass) {
    // Handle references to XMM physical registers that got mapped into the
    // wrong class.  This can happen with constraints like {xmm0} where the
    // target independent register mapper will just pick the first match it can
    // find, ignoring the required type.
    if (VT == MVT::f32)
      Res.second = X86::FR32RegisterClass;
    else if (VT == MVT::f64)
      Res.second = X86::FR64RegisterClass;
    else if (X86::VR128RegisterClass->hasType(VT))
      Res.second = X86::VR128RegisterClass;
  }

  return Res;
}