src/IceTargetLoweringX8632.cpp

//===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
//
//                        The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the TargetLoweringX8632 class, which
/// consists almost entirely of the lowering sequence for each
/// high-level instruction.
///
//===----------------------------------------------------------------------===//

#include "IceTargetLoweringX8632.h"

#include "IceTargetLoweringX8632Traits.h"
#include "IceTargetLoweringX86Base.h"

namespace Ice {

//------------------------------------------------------------------------------
//      ______   ______     ______     __     ______   ______
//     /\__  _\ /\  == \   /\  __ \   /\ \   /\__  _\ /\  ___\
//     \/_/\ \/ \ \  __<   \ \  __ \  \ \ \  \/_/\ \/ \ \___  \
//        \ \_\  \ \_\ \_\  \ \_\ \_\  \ \_\    \ \_\  \/\_____\
//         \/_/   \/_/ /_/   \/_/\/_/   \/_/     \/_/   \/_____/
//
//------------------------------------------------------------------------------
namespace X86Internal {
const MachineTraits<TargetX8632>::TableFcmpType
    MachineTraits<TargetX8632>::TableFcmp[] = {
#define X(val, dflt, swapS, C1, C2, swapV, pred)                               \
  {                                                                            \
    dflt, swapS, X8632::Traits::Cond::C1, X8632::Traits::Cond::C2, swapV,      \
        X8632::Traits::Cond::pred                                              \
  }                                                                            \
  ,
        FCMPX8632_TABLE
#undef X
};

const size_t MachineTraits<TargetX8632>::TableFcmpSize =
    llvm::array_lengthof(TableFcmp);

const MachineTraits<TargetX8632>::TableIcmp32Type
    MachineTraits<TargetX8632>::TableIcmp32[] = {
#define X(val, C_32, C1_64, C2_64, C3_64)                                      \
  { X8632::Traits::Cond::C_32 }                                                \
  ,
        ICMPX8632_TABLE
#undef X
};

const size_t MachineTraits<TargetX8632>::TableIcmp32Size =
    llvm::array_lengthof(TableIcmp32);

const MachineTraits<TargetX8632>::TableIcmp64Type
    MachineTraits<TargetX8632>::TableIcmp64[] = {
#define X(val, C_32, C1_64, C2_64, C3_64)                                      \
  {                                                                            \
    X8632::Traits::Cond::C1_64, X8632::Traits::Cond::C2_64,                    \
        X8632::Traits::Cond::C3_64                                             \
  }                                                                            \
  ,
        ICMPX8632_TABLE
#undef X
};

const size_t MachineTraits<TargetX8632>::TableIcmp64Size =
    llvm::array_lengthof(TableIcmp64);

const MachineTraits<TargetX8632>::TableTypeX8632AttributesType
    MachineTraits<TargetX8632>::TableTypeX8632Attributes[] = {
#define X(tag, elementty, cvt, sdss, pack, width, fld)                         \
  { elementty }                                                                \
  ,
        ICETYPEX8632_TABLE
#undef X
};

const size_t MachineTraits<TargetX8632>::TableTypeX8632AttributesSize =
    llvm::array_lengthof(TableTypeX8632Attributes);

const uint32_t MachineTraits<TargetX8632>::X86_STACK_ALIGNMENT_BYTES = 16;
const char *MachineTraits<TargetX8632>::TargetName = "X8632";

} // end of namespace X86Internal

TargetDataX8632::TargetDataX8632(GlobalContext *Ctx)
    : TargetDataLowering(Ctx) {}

namespace {
template <typename T> struct PoolTypeConverter {};

template <> struct PoolTypeConverter<float> {
  typedef uint32_t PrimitiveIntType;
  typedef ConstantFloat IceType;
  static const Type Ty = IceType_f32;
  static const char *TypeName;
  static const char *AsmTag;
  static const char *PrintfString;
};
const char *PoolTypeConverter<float>::TypeName = "float";
const char *PoolTypeConverter<float>::AsmTag = ".long";
const char *PoolTypeConverter<float>::PrintfString = "0x%x";

template <> struct PoolTypeConverter<double> {
  typedef uint64_t PrimitiveIntType;
  typedef ConstantDouble IceType;
  static const Type Ty = IceType_f64;
  static const char *TypeName;
  static const char *AsmTag;
  static const char *PrintfString;
};
const char *PoolTypeConverter<double>::TypeName = "double";
const char *PoolTypeConverter<double>::AsmTag = ".quad";
const char *PoolTypeConverter<double>::PrintfString = "0x%llx";

// Add converter for int type constant pooling
template <> struct PoolTypeConverter<uint32_t> {
  typedef uint32_t PrimitiveIntType;
  typedef ConstantInteger32 IceType;
  static const Type Ty = IceType_i32;
  static const char *TypeName;
  static const char *AsmTag;
  static const char *PrintfString;
};
const char *PoolTypeConverter<uint32_t>::TypeName = "i32";
const char *PoolTypeConverter<uint32_t>::AsmTag = ".long";
const char *PoolTypeConverter<uint32_t>::PrintfString = "0x%x";

// Add converter for int type constant pooling
template <> struct PoolTypeConverter<uint16_t> {
  typedef uint32_t PrimitiveIntType;
  typedef ConstantInteger32 IceType;
  static const Type Ty = IceType_i16;
  static const char *TypeName;
  static const char *AsmTag;
  static const char *PrintfString;
};
const char *PoolTypeConverter<uint16_t>::TypeName = "i16";
const char *PoolTypeConverter<uint16_t>::AsmTag = ".short";
const char *PoolTypeConverter<uint16_t>::PrintfString = "0x%x";

// Add converter for int type constant pooling
template <> struct PoolTypeConverter<uint8_t> {
  typedef uint32_t PrimitiveIntType;
  typedef ConstantInteger32 IceType;
  static const Type Ty = IceType_i8;
  static const char *TypeName;
  static const char *AsmTag;
  static const char *PrintfString;
};
const char *PoolTypeConverter<uint8_t>::TypeName = "i8";
const char *PoolTypeConverter<uint8_t>::AsmTag = ".byte";
const char *PoolTypeConverter<uint8_t>::PrintfString = "0x%x";
} // end of anonymous namespace

void TargetX8632::emitJumpTable(const Cfg *Func,
                                const InstJumpTable *JumpTable) const {
  if (!BuildDefs::dump())
    return;
  Ostream &Str = Ctx->getStrEmit();
  IceString MangledName = Ctx->mangleName(Func->getFunctionName());
  Str << "\t.section\t.rodata." << MangledName
      << "$jumptable,\"a\",@progbits\n";
  Str << "\t.align\t" << typeWidthInBytes(getPointerType()) << "\n";
  Str << InstJumpTable::makeName(MangledName, JumpTable->getId()) << ":";

  // On X8632 pointers are 32-bit hence the use of .long
  for (SizeT I = 0; I < JumpTable->getNumTargets(); ++I)
    Str << "\n\t.long\t" << JumpTable->getTarget(I)->getAsmName();
  Str << "\n";
}

template <typename T>
void TargetDataX8632::emitConstantPool(GlobalContext *Ctx) {
  if (!BuildDefs::dump())
    return;
  Ostream &Str = Ctx->getStrEmit();
  Type Ty = T::Ty;
  SizeT Align = typeAlignInBytes(Ty);
  ConstantList Pool = Ctx->getConstantPool(Ty);

  Str << "\t.section\t.rodata.cst" << Align << ",\"aM\",@progbits," << Align
      << "\n";
  Str << "\t.align\t" << Align << "\n";

  // If reorder-pooled-constants option is set to true, we need to shuffle the
  // constant pool before emitting it.
  if (Ctx->getFlags().shouldReorderPooledConstants())
    RandomShuffle(Pool.begin(), Pool.end(), [Ctx](uint64_t N) {
      return (uint32_t)Ctx->getRNG().next(N);
    });

  for (Constant *C : Pool) {
    if (!C->getShouldBePooled())
      continue;
    typename T::IceType *Const = llvm::cast<typename T::IceType>(C);
    typename T::IceType::PrimType Value = Const->getValue();
    // Use memcpy() to copy bits from Value into RawValue in a way
    // that avoids breaking strict-aliasing rules.
    typename T::PrimitiveIntType RawValue;
    memcpy(&RawValue, &Value, sizeof(Value));
    char buf[30];
    int CharsPrinted =
        snprintf(buf, llvm::array_lengthof(buf), T::PrintfString, RawValue);
    assert(CharsPrinted >= 0 &&
           (size_t)CharsPrinted < llvm::array_lengthof(buf));
    (void)CharsPrinted; // avoid warnings if asserts are disabled
    Const->emitPoolLabel(Str);
    Str << ":\n\t" << T::AsmTag << "\t" << buf << "\t# " << T::TypeName << " "
        << Value << "\n";
  }
}

void TargetDataX8632::lowerConstants() {
  if (Ctx->getFlags().getDisableTranslation())
    return;
  // No need to emit constants from the int pool since (for x86) they
  // are embedded as immediates in the instructions, just emit float/double.
  switch (Ctx->getFlags().getOutFileType()) {
  case FT_Elf: {
    ELFObjectWriter *Writer = Ctx->getObjectWriter();

    Writer->writeConstantPool<ConstantInteger32>(IceType_i8);
    Writer->writeConstantPool<ConstantInteger32>(IceType_i16);
    Writer->writeConstantPool<ConstantInteger32>(IceType_i32);

    Writer->writeConstantPool<ConstantFloat>(IceType_f32);
    Writer->writeConstantPool<ConstantDouble>(IceType_f64);
  } break;
  case FT_Asm:
  case FT_Iasm: {
    OstreamLocker L(Ctx);

    emitConstantPool<PoolTypeConverter<uint8_t>>(Ctx);
    emitConstantPool<PoolTypeConverter<uint16_t>>(Ctx);
    emitConstantPool<PoolTypeConverter<uint32_t>>(Ctx);

    emitConstantPool<PoolTypeConverter<float>>(Ctx);
    emitConstantPool<PoolTypeConverter<double>>(Ctx);
  } break;
  }
}

void TargetDataX8632::lowerJumpTables() {
  switch (Ctx->getFlags().getOutFileType()) {
  case FT_Elf: {
    ELFObjectWriter *Writer = Ctx->getObjectWriter();
    for (const JumpTableData &JT : Ctx->getJumpTables())
      Writer->writeJumpTable(JT, llvm::ELF::R_386_32);
  } break;
  case FT_Asm:
    // Already emitted from Cfg
    break;
  case FT_Iasm: {
    if (!BuildDefs::dump())
      return;
    Ostream &Str = Ctx->getStrEmit();
    for (const JumpTableData &JT : Ctx->getJumpTables()) {
      Str << "\t.section\t.rodata." << JT.getFunctionName()
          << "$jumptable,\"a\",@progbits\n";
      Str << "\t.align\t" << typeWidthInBytes(getPointerType()) << "\n";
      Str << InstJumpTable::makeName(JT.getFunctionName(), JT.getId()) << ":";

      // On X8632 pointers are 32-bit hence the use of .long
      for (intptr_t TargetOffset : JT.getTargetOffsets())
        Str << "\n\t.long\t" << JT.getFunctionName() << "+" << TargetOffset;
      Str << "\n";
    }
  } break;
  }
}

void TargetDataX8632::lowerGlobals(const VariableDeclarationList &Vars,
                                   const IceString &SectionSuffix) {
  switch (Ctx->getFlags().getOutFileType()) {
  case FT_Elf: {
    ELFObjectWriter *Writer = Ctx->getObjectWriter();
    Writer->writeDataSection(Vars, llvm::ELF::R_386_32, SectionSuffix);
  } break;
  case FT_Asm:
  case FT_Iasm: {
    const IceString &TranslateOnly = Ctx->getFlags().getTranslateOnly();
    OstreamLocker L(Ctx);
    for (const VariableDeclaration *Var : Vars) {
      if (GlobalContext::matchSymbolName(Var->getName(), TranslateOnly)) {
        emitGlobal(*Var, SectionSuffix);
      }
    }
  } break;
  }
}

TargetHeaderX8632::TargetHeaderX8632(GlobalContext *Ctx)
    : TargetHeaderLowering(Ctx) {}

// In some cases, there are x-macros tables for both high-level and
// low-level instructions/operands that use the same enum key value.
// The tables are kept separate to maintain a proper separation
// between abstraction layers.  There is a risk that the tables could
// get out of sync if enum values are reordered or if entries are
// added or deleted.  The following dummy namespaces use
// static_asserts to ensure everything is kept in sync.

namespace {
// Validate the enum values in FCMPX8632_TABLE.
namespace dummy1 {
// Define a temporary set of enum values based on low-level table
// entries.
enum _tmp_enum {
#define X(val, dflt, swapS, C1, C2, swapV, pred) _tmp_##val,
  FCMPX8632_TABLE
#undef X
      _num
};
// Define a set of constants based on high-level table entries.
#define X(tag, str) static const int _table1_##tag = InstFcmp::tag;
ICEINSTFCMP_TABLE
#undef X
// Define a set of constants based on low-level table entries, and
// ensure the table entry keys are consistent.
#define X(val, dflt, swapS, C1, C2, swapV, pred)                               \
  static const int _table2_##val = _tmp_##val;                                 \
  static_assert(                                                               \
      _table1_##val == _table2_##val,                                          \
      "Inconsistency between FCMPX8632_TABLE and ICEINSTFCMP_TABLE");
FCMPX8632_TABLE
#undef X
// Repeat the static asserts with respect to the high-level table
// entries in case the high-level table has extra entries.
#define X(tag, str)                                                            \
  static_assert(                                                               \
      _table1_##tag == _table2_##tag,                                          \
      "Inconsistency between FCMPX8632_TABLE and ICEINSTFCMP_TABLE");
ICEINSTFCMP_TABLE
#undef X
} // end of namespace dummy1

// Validate the enum values in ICMPX8632_TABLE.
namespace dummy2 {
// Define a temporary set of enum values based on low-level table
// entries.
enum _tmp_enum {
#define X(val, C_32, C1_64, C2_64, C3_64) _tmp_##val,
  ICMPX8632_TABLE
#undef X
      _num
};
// Define a set of constants based on high-level table entries.
#define X(tag, str) static const int _table1_##tag = InstIcmp::tag;
ICEINSTICMP_TABLE
#undef X
// Define a set of constants based on low-level table entries, and
// ensure the table entry keys are consistent.
#define X(val, C_32, C1_64, C2_64, C3_64)                                      \
  static const int _table2_##val = _tmp_##val;                                 \
  static_assert(                                                               \
      _table1_##val == _table2_##val,                                          \
      "Inconsistency between ICMPX8632_TABLE and ICEINSTICMP_TABLE");
ICMPX8632_TABLE
#undef X
// Repeat the static asserts with respect to the high-level table
// entries in case the high-level table has extra entries.
#define X(tag, str)                                                            \
  static_assert(                                                               \
      _table1_##tag == _table2_##tag,                                          \
      "Inconsistency between ICMPX8632_TABLE and ICEINSTICMP_TABLE");
ICEINSTICMP_TABLE
#undef X
} // end of namespace dummy2

// Validate the enum values in ICETYPEX8632_TABLE.
namespace dummy3 {
// Define a temporary set of enum values based on low-level table
// entries.
enum _tmp_enum {
#define X(tag, elementty, cvt, sdss, pack, width, fld) _tmp_##tag,
  ICETYPEX8632_TABLE
#undef X
      _num
};
// Define a set of constants based on high-level table entries.
#define X(tag, sizeLog2, align, elts, elty, str)                               \
  static const int _table1_##tag = tag;
ICETYPE_TABLE
#undef X
// Define a set of constants based on low-level table entries, and
// ensure the table entry keys are consistent.
#define X(tag, elementty, cvt, sdss, pack, width, fld)                         \
  static const int _table2_##tag = _tmp_##tag;                                 \
  static_assert(_table1_##tag == _table2_##tag,                                \
                "Inconsistency between ICETYPEX8632_TABLE and ICETYPE_TABLE");
ICETYPEX8632_TABLE
#undef X
// Repeat the static asserts with respect to the high-level table
// entries in case the high-level table has extra entries.
#define X(tag, sizeLog2, align, elts, elty, str)                               \
  static_assert(_table1_##tag == _table2_##tag,                                \
                "Inconsistency between ICETYPEX8632_TABLE and ICETYPE_TABLE");
ICETYPE_TABLE
#undef X
} // end of namespace dummy3
} // end of anonymous namespace

//------------------------------------------------------------------------------
//     __      ______  __     __  ______  ______  __  __   __  ______
//    /\ \    /\  __ \/\ \  _ \ \/\  ___\/\  == \/\ \/\ "-.\ \/\  ___\
//    \ \ \___\ \ \/\ \ \ \/ ".\ \ \  __\\ \  __<\ \ \ \ \-.  \ \ \__ \
//     \ \_____\ \_____\ \__/".~\_\ \_____\ \_\ \_\ \_\ \_\\"\_\ \_____\
//      \/_____/\/_____/\/_/   \/_/\/_____/\/_/ /_/\/_/\/_/ \/_/\/_____/
//
//------------------------------------------------------------------------------
void TargetX8632::lowerCall(const InstCall *Instr) {
  // x86-32 calling convention:
  //
  // * At the point before the call, the stack must be aligned to 16
  // bytes.
  //
  // * The first four arguments of vector type, regardless of their
  // position relative to the other arguments in the argument list, are
  // placed in registers xmm0 - xmm3.
  //
  // * Other arguments are pushed onto the stack in right-to-left order,
  // such that the left-most argument ends up on the top of the stack at
  // the lowest memory address.
  //
  // * Stack arguments of vector type are aligned to start at the next
  // highest multiple of 16 bytes.  Other stack arguments are aligned to
  // 4 bytes.
  //
  // This intends to match the section "IA-32 Function Calling
  // Convention" of the document "OS X ABI Function Call Guide" by
  // Apple.
  NeedsStackAlignment = true;

  typedef std::vector<Operand *> OperandList;
  OperandList XmmArgs;
  OperandList StackArgs, StackArgLocations;
  uint32_t ParameterAreaSizeBytes = 0;

  // Classify each argument operand according to the location where the
  // argument is passed.
  for (SizeT i = 0, NumArgs = Instr->getNumArgs(); i < NumArgs; ++i) {
    Operand *Arg = Instr->getArg(i);
    Type Ty = Arg->getType();
    // The PNaCl ABI requires the width of arguments to be at least 32 bits.
    assert(typeWidthInBytes(Ty) >= 4);
    if (isVectorType(Ty) && XmmArgs.size() < Traits::X86_MAX_XMM_ARGS) {
      XmmArgs.push_back(Arg);
    } else {
      StackArgs.push_back(Arg);
      if (isVectorType(Arg->getType())) {
        ParameterAreaSizeBytes =
            Traits::applyStackAlignment(ParameterAreaSizeBytes);
      }
      Variable *esp =
          Func->getTarget()->getPhysicalRegister(Traits::RegisterSet::Reg_esp);
      Constant *Loc = Ctx->getConstantInt32(ParameterAreaSizeBytes);
      StackArgLocations.push_back(
          Traits::X86OperandMem::create(Func, Ty, esp, Loc));
      ParameterAreaSizeBytes += typeWidthInBytesOnStack(Arg->getType());
    }
  }

  // Adjust the parameter area so that the stack is aligned.  It is
  // assumed that the stack is already aligned at the start of the
  // calling sequence.
  ParameterAreaSizeBytes = Traits::applyStackAlignment(ParameterAreaSizeBytes);

  // Subtract the appropriate amount for the argument area.  This also
  // takes care of setting the stack adjustment during emission.
  //
  // TODO: If for some reason the call instruction gets dead-code
  // eliminated after lowering, we would need to ensure that the
  // pre-call and the post-call esp adjustment get eliminated as well.
  if (ParameterAreaSizeBytes) {
    _adjust_stack(ParameterAreaSizeBytes);
  }

  // Copy arguments that are passed on the stack to the appropriate
  // stack locations.
  for (SizeT i = 0, e = StackArgs.size(); i < e; ++i) {
    lowerStore(InstStore::create(Func, StackArgs[i], StackArgLocations[i]));
  }

  // Copy arguments to be passed in registers to the appropriate
  // registers.
  // TODO: Investigate the impact of lowering arguments passed in
  // registers after lowering stack arguments as opposed to the other
  // way around.  Lowering register arguments after stack arguments may
  // reduce register pressure.  On the other hand, lowering register
  // arguments first (before stack arguments) may result in more compact
  // code, as the memory operand displacements may end up being smaller
  // before any stack adjustment is done.
  for (SizeT i = 0, NumXmmArgs = XmmArgs.size(); i < NumXmmArgs; ++i) {
    Variable *Reg =
        legalizeToReg(XmmArgs[i], Traits::RegisterSet::Reg_xmm0 + i);
    // Generate a FakeUse of register arguments so that they do not get
    // dead code eliminated as a result of the FakeKill of scratch
    // registers after the call.
    Context.insert(InstFakeUse::create(Func, Reg));
  }
  // Generate the call instruction.  Assign its result to a temporary
  // with high register allocation weight.
  Variable *Dest = Instr->getDest();
  // ReturnReg doubles as ReturnRegLo as necessary.
  Variable *ReturnReg = nullptr;
  Variable *ReturnRegHi = nullptr;
  if (Dest) {
    switch (Dest->getType()) {
    case IceType_NUM:
      llvm_unreachable("Invalid Call dest type");
      break;
    case IceType_void:
      break;
    case IceType_i1:
    case IceType_i8:
    case IceType_i16:
    case IceType_i32:
      ReturnReg = makeReg(Dest->getType(), Traits::RegisterSet::Reg_eax);
      break;
    case IceType_i64:
      ReturnReg = makeReg(IceType_i32, Traits::RegisterSet::Reg_eax);
      ReturnRegHi = makeReg(IceType_i32, Traits::RegisterSet::Reg_edx);
      break;
    case IceType_f32:
    case IceType_f64:
      // Leave ReturnReg==ReturnRegHi==nullptr, and capture the result with
      // the fstp instruction.
      break;
    case IceType_v4i1:
    case IceType_v8i1:
    case IceType_v16i1:
    case IceType_v16i8:
    case IceType_v8i16:
    case IceType_v4i32:
    case IceType_v4f32:
      ReturnReg = makeReg(Dest->getType(), Traits::RegisterSet::Reg_xmm0);
      break;
    }
  }
  Operand *CallTarget = legalize(Instr->getCallTarget());
  const bool NeedSandboxing = Ctx->getFlags().getUseSandboxing();
  if (NeedSandboxing) {
    if (llvm::isa<Constant>(CallTarget)) {
      _bundle_lock(InstBundleLock::Opt_AlignToEnd);
    } else {
      Variable *CallTargetVar = nullptr;
      _mov(CallTargetVar, CallTarget);
      _bundle_lock(InstBundleLock::Opt_AlignToEnd);
      const SizeT BundleSize =
          1 << Func->getAssembler<>()->getBundleAlignLog2Bytes();
      _and(CallTargetVar, Ctx->getConstantInt32(~(BundleSize - 1)));
      CallTarget = CallTargetVar;
    }
  }
  Inst *NewCall = Traits::Insts::Call::create(Func, ReturnReg, CallTarget);
  Context.insert(NewCall);
  if (NeedSandboxing)
    _bundle_unlock();
  if (ReturnRegHi)
    Context.insert(InstFakeDef::create(Func, ReturnRegHi));

  // Add the appropriate offset to esp.  The call instruction takes care
  // of resetting the stack offset during emission.
  if (ParameterAreaSizeBytes) {
    Variable *esp =
        Func->getTarget()->getPhysicalRegister(Traits::RegisterSet::Reg_esp);
    _add(esp, Ctx->getConstantInt32(ParameterAreaSizeBytes));
  }

  // Insert a register-kill pseudo instruction.
  Context.insert(InstFakeKill::create(Func, NewCall));

  // Generate a FakeUse to keep the call live if necessary.
  if (Instr->hasSideEffects() && ReturnReg) {
    Inst *FakeUse = InstFakeUse::create(Func, ReturnReg);
    Context.insert(FakeUse);
  }

  if (!Dest)
    return;

  // Assign the result of the call to Dest.
  if (ReturnReg) {
    if (ReturnRegHi) {
      assert(Dest->getType() == IceType_i64);
      split64(Dest);
      Variable *DestLo = Dest->getLo();
      Variable *DestHi = Dest->getHi();
      _mov(DestLo, ReturnReg);
      _mov(DestHi, ReturnRegHi);
    } else {
      assert(Dest->getType() == IceType_i32 || Dest->getType() == IceType_i16 ||
             Dest->getType() == IceType_i8 || Dest->getType() == IceType_i1 ||
             isVectorType(Dest->getType()));
      if (isVectorType(Dest->getType())) {
        _movp(Dest, ReturnReg);
      } else {
        _mov(Dest, ReturnReg);
      }
    }
  } else if (isScalarFloatingType(Dest->getType())) {
    // Special treatment for an FP function which returns its result in
    // st(0).
    // If Dest ends up being a physical xmm register, the fstp emit code
    // will route st(0) through a temporary stack slot.
    _fstp(Dest);
    // Create a fake use of Dest in case it actually isn't used,
    // because st(0) still needs to be popped.
    Context.insert(InstFakeUse::create(Func, Dest));
  }
}

} // end of namespace Ice