path: root/js/src/jit/IonTypes.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jit_IonTypes_h
#define jit_IonTypes_h

#include "mozilla/HashFunctions.h"

#include <algorithm>

#include "jsfriendapi.h"
#include "jstypes.h"

#include "js/GCAPI.h"
#include "js/Value.h"
#include "vm/String.h"

namespace js {
namespace jit {

typedef uint32_t RecoverOffset;
typedef uint32_t SnapshotOffset;
typedef uint32_t BailoutId;

// The maximum size of any buffer associated with an assembler or code object.
// This is chosen to not overflow a signed integer, leaving room for an extra
// bit on offsets.
static const uint32_t MAX_BUFFER_SIZE = (1 << 30) - 1;

// Maximum number of scripted arg slots.
static const uint32_t SNAPSHOT_MAX_NARGS = 127;

static const SnapshotOffset INVALID_RECOVER_OFFSET = uint32_t(-1);
static const SnapshotOffset INVALID_SNAPSHOT_OFFSET = uint32_t(-1);

// Different kinds of bailouts. When extending this enum, make sure to check
// the bits reserved for bailout kinds in Bailouts.h
enum BailoutKind
{
    // Normal bailouts, that don't need to be handled specially when restarting
    // in baseline.

    // An inevitable bailout (MBail instruction or type barrier that always bails)
    Bailout_Inevitable,

    // Bailing out during a VM call. Many possible causes that are hard
    // to distinguish statically at snapshot construction time.
    // We just lump them together.
    Bailout_DuringVMCall,

    // Call to a non-JSFunction (problem for |apply|)
    Bailout_NonJSFunctionCallee,

    // Dynamic scope chain lookup produced |undefined|
    Bailout_DynamicNameNotFound,

    // Input string contains 'arguments' or 'eval'
    Bailout_StringArgumentsEval,

    // Bailout on overflow, but don't immediately invalidate.
    // Used for abs, sub and LoadUnboxedScalar (when loading a uint32 that
    // doesn't fit in an int32).
    Bailout_Overflow,

    // floor, ceiling and round bail if input is NaN, if output would be -0 or
    // doesn't fit in int32 range
    Bailout_Round,

    // Non-primitive value used as input for ToDouble, ToInt32, ToString, etc.
    // For ToInt32, can also mean that input can't be converted without precision
    // loss (e.g. 5.5).
    Bailout_NonPrimitiveInput,

    // For ToInt32, would lose precision when converting (e.g. 5.5).
    Bailout_PrecisionLoss,

    // We tripped a type barrier (object was not in the expected TypeSet)
    Bailout_TypeBarrierO,
    // We tripped a type barrier (value was not in the expected TypeSet)
    Bailout_TypeBarrierV,
    // We tripped a type monitor (wrote an unexpected type in a property)
    Bailout_MonitorTypes,

    // We hit a hole in an array.
    Bailout_Hole,

    // Array access with negative index
    Bailout_NegativeIndex,

    // Pretty specific case:
    //  - need a type barrier on a property write
    //  - all but one of the observed types have property types that reflect the value
    //  - we need to guard that we're not given an object of that one other type
    // also used for the unused GuardClass instruction
    Bailout_ObjectIdentityOrTypeGuard,

    // Unbox expects a given type, bails out if it doesn't get it.
    Bailout_NonInt32Input,
    Bailout_NonNumericInput, // unboxing a double works with int32 too
    Bailout_NonBooleanInput,
    Bailout_NonObjectInput,
    Bailout_NonStringInput,
    Bailout_NonSymbolInput,

    // SIMD Unbox expects a given type, bails out if it doesn't match.
    Bailout_UnexpectedSimdInput,

    // Atomic operations require shared memory, bail out if the typed array
    // maps unshared memory.
    Bailout_NonSharedTypedArrayInput,

    // We hit a |debugger;| statement.
    Bailout_Debugger,

    // |this| used uninitialized in a derived constructor
    Bailout_UninitializedThis,

    // Derived constructors must return object or undefined
    Bailout_BadDerivedConstructorReturn,

    // We hit this code for the first time.
    Bailout_FirstExecution,

    // END Normal bailouts

    // Bailouts caused by invalid assumptions based on Baseline code.
    // Causes immediate invalidation.

    // Like Bailout_Overflow, but causes immediate invalidation.
    Bailout_OverflowInvalidate,

    // Like NonStringInput, but should cause immediate invalidation.
    // Used for jsop_iternext.
    Bailout_NonStringInputInvalidate,

    // Used for integer division, multiplication and modulo.
    // If there's a remainder, bails to return a double.
    // Can also signal overflow or result of -0.
    // Can also signal division by 0 (returns inf, a double).
    Bailout_DoubleOutput,

    // END Invalid assumptions bailouts


    // A bailout at the very start of a function indicates that there may be
    // a type mismatch in the arguments that necessitates a reflow.
    Bailout_ArgumentCheck,

    // A bailout triggered by a bounds-check failure.
    Bailout_BoundsCheck,
    // A bailout triggered by a typed object whose backing buffer was detached.
    Bailout_Detached,

    // A shape guard based on TI information failed.
    // (We saw an object whose shape does not match that / any of those observed
    // by the baseline IC.)
    Bailout_ShapeGuard,

    // When we're trying to use an uninitialized lexical.
    Bailout_UninitializedLexical,

    // A bailout to baseline from Ion on exception to handle Debugger hooks.
    Bailout_IonExceptionDebugMode
};

inline const char*
BailoutKindString(BailoutKind kind)
{
    switch (kind) {
      // Normal bailouts.
      case Bailout_Inevitable:
        return "Bailout_Inevitable";
      case Bailout_DuringVMCall:
        return "Bailout_DuringVMCall";
      case Bailout_NonJSFunctionCallee:
        return "Bailout_NonJSFunctionCallee";
      case Bailout_DynamicNameNotFound:
        return "Bailout_DynamicNameNotFound";
      case Bailout_StringArgumentsEval:
        return "Bailout_StringArgumentsEval";
      case Bailout_Overflow:
        return "Bailout_Overflow";
      case Bailout_Round:
        return "Bailout_Round";
      case Bailout_NonPrimitiveInput:
        return "Bailout_NonPrimitiveInput";
      case Bailout_PrecisionLoss:
        return "Bailout_PrecisionLoss";
      case Bailout_TypeBarrierO:
        return "Bailout_TypeBarrierO";
      case Bailout_TypeBarrierV:
        return "Bailout_TypeBarrierV";
      case Bailout_MonitorTypes:
        return "Bailout_MonitorTypes";
      case Bailout_Hole:
        return "Bailout_Hole";
      case Bailout_NegativeIndex:
        return "Bailout_NegativeIndex";
      case Bailout_ObjectIdentityOrTypeGuard:
        return "Bailout_ObjectIdentityOrTypeGuard";
      case Bailout_NonInt32Input:
        return "Bailout_NonInt32Input";
      case Bailout_NonNumericInput:
        return "Bailout_NonNumericInput";
      case Bailout_NonBooleanInput:
        return "Bailout_NonBooleanInput";
      case Bailout_NonObjectInput:
        return "Bailout_NonObjectInput";
      case Bailout_NonStringInput:
        return "Bailout_NonStringInput";
      case Bailout_NonSymbolInput:
        return "Bailout_NonSymbolInput";
      case Bailout_UnexpectedSimdInput:
        return "Bailout_UnexpectedSimdInput";
      case Bailout_NonSharedTypedArrayInput:
        return "Bailout_NonSharedTypedArrayInput";
      case Bailout_Debugger:
        return "Bailout_Debugger";
      case Bailout_UninitializedThis:
        return "Bailout_UninitializedThis";
      case Bailout_BadDerivedConstructorReturn:
        return "Bailout_BadDerivedConstructorReturn";
      case Bailout_FirstExecution:
        return "Bailout_FirstExecution";

      // Bailouts caused by invalid assumptions.
      case Bailout_OverflowInvalidate:
        return "Bailout_OverflowInvalidate";
      case Bailout_NonStringInputInvalidate:
        return "Bailout_NonStringInputInvalidate";
      case Bailout_DoubleOutput:
        return "Bailout_DoubleOutput";

      // Other bailouts.
      case Bailout_ArgumentCheck:
        return "Bailout_ArgumentCheck";
      case Bailout_BoundsCheck:
        return "Bailout_BoundsCheck";
      case Bailout_Detached:
        return "Bailout_Detached";
      case Bailout_ShapeGuard:
        return "Bailout_ShapeGuard";
      case Bailout_UninitializedLexical:
        return "Bailout_UninitializedLexical";
      case Bailout_IonExceptionDebugMode:
        return "Bailout_IonExceptionDebugMode";
      default:
        MOZ_CRASH("Invalid BailoutKind");
    }
}

static const uint32_t ELEMENT_TYPE_BITS = 5;
static const uint32_t ELEMENT_TYPE_SHIFT = 0;
static const uint32_t ELEMENT_TYPE_MASK = (1 << ELEMENT_TYPE_BITS) - 1;
static const uint32_t VECTOR_SCALE_BITS = 3;
static const uint32_t VECTOR_SCALE_SHIFT = ELEMENT_TYPE_BITS + ELEMENT_TYPE_SHIFT;
static const uint32_t VECTOR_SCALE_MASK = (1 << VECTOR_SCALE_BITS) - 1;

class SimdConstant {
  public:
    enum Type {
        Int8x16,
        Int16x8,
        Int32x4,
        Float32x4,
        Undefined = -1
    };

    typedef int8_t I8x16[16];
    typedef int16_t I16x8[8];
    typedef int32_t I32x4[4];
    typedef float F32x4[4];

  private:
    Type type_;
    union {
        I8x16 i8x16;
        I16x8 i16x8;
        I32x4 i32x4;
        F32x4 f32x4;
    } u;

    bool defined() const {
        return type_ != Undefined;
    }

  public:
    // Doesn't have a default constructor, as it would prevent it from being
    // included in unions.

    static SimdConstant CreateX16(const int8_t* array) {
        SimdConstant cst;
        cst.type_ = Int8x16;
        memcpy(cst.u.i8x16, array, sizeof(cst.u));
        return cst;
    }
    static SimdConstant SplatX16(int8_t v) {
        SimdConstant cst;
        cst.type_ = Int8x16;
        std::fill_n(cst.u.i8x16, 16, v);
        return cst;
    }
    static SimdConstant CreateX8(const int16_t* array) {
        SimdConstant cst;
        cst.type_ = Int16x8;
        memcpy(cst.u.i16x8, array, sizeof(cst.u));
        return cst;
    }
    static SimdConstant SplatX8(int16_t v) {
        SimdConstant cst;
        cst.type_ = Int16x8;
        std::fill_n(cst.u.i16x8, 8, v);
        return cst;
    }
    static SimdConstant CreateX4(const int32_t* array) {
        SimdConstant cst;
        cst.type_ = Int32x4;
        memcpy(cst.u.i32x4, array, sizeof(cst.u));
        return cst;
    }
    static SimdConstant SplatX4(int32_t v) {
        SimdConstant cst;
        cst.type_ = Int32x4;
        std::fill_n(cst.u.i32x4, 4, v);
        return cst;
    }
    static SimdConstant CreateX4(const float* array) {
        SimdConstant cst;
        cst.type_ = Float32x4;
        memcpy(cst.u.f32x4, array, sizeof(cst.u));
        return cst;
    }
    static SimdConstant SplatX4(float v) {
        SimdConstant cst;
        cst.type_ = Float32x4;
        std::fill_n(cst.u.f32x4, 4, v);
        return cst;
    }

    // Overloads for use by templates.
    static SimdConstant CreateSimd128(const int8_t* array) { return CreateX16(array); }
    static SimdConstant CreateSimd128(const int16_t* array) { return CreateX8(array); }
    static SimdConstant CreateSimd128(const int32_t* array) { return CreateX4(array); }
    static SimdConstant CreateSimd128(const float* array) { return CreateX4(array); }

    Type type() const {
        MOZ_ASSERT(defined());
        return type_;
    }

    // Get the raw bytes of the constant.
    const void* bytes() const {
        return u.i8x16;
    }

    const I8x16& asInt8x16() const {
        MOZ_ASSERT(defined() && type_ == Int8x16);
        return u.i8x16;
    }

    const I16x8& asInt16x8() const {
        MOZ_ASSERT(defined() && type_ == Int16x8);
        return u.i16x8;
    }

    const I32x4& asInt32x4() const {
        MOZ_ASSERT(defined() && type_ == Int32x4);
        return u.i32x4;
    }

    const F32x4& asFloat32x4() const {
        MOZ_ASSERT(defined() && type_ == Float32x4);
        return u.f32x4;
    }

    bool operator==(const SimdConstant& rhs) const {
        MOZ_ASSERT(defined() && rhs.defined());
        if (type() != rhs.type())
            return false;
        // Takes negative zero into accuont, as it's a bit comparison.
        return memcmp(&u, &rhs.u, sizeof(u)) == 0;
    }
    bool operator!=(const SimdConstant& rhs) const {
        return !operator==(rhs);
    }

    // SimdConstant is a HashPolicy
    typedef SimdConstant Lookup;
    static HashNumber hash(const SimdConstant& val) {
        uint32_t hash = mozilla::HashBytes(&val.u, sizeof(val.u));
        return mozilla::AddToHash(hash, val.type_);
    }
    static bool match(const SimdConstant& lhs, const SimdConstant& rhs) {
        return lhs == rhs;
    }
};

// The ordering of this enumeration is important: Anything < Value is a
// specialized type. Furthermore, anything < String has trivial conversion to
// a number.
enum class MIRType
{
    Undefined,
    Null,
    Boolean,
    Int32,
    Int64,
    Double,
    Float32,
    // Types above have trivial conversion to a number.
    String,
    Symbol,
    // Types above are primitive (including undefined and null).
    Object,
    MagicOptimizedArguments,   // JS_OPTIMIZED_ARGUMENTS magic value.
    MagicOptimizedOut,         // JS_OPTIMIZED_OUT magic value.
    MagicHole,                 // JS_ELEMENTS_HOLE magic value.
    MagicIsConstructing,       // JS_IS_CONSTRUCTING magic value.
    MagicUninitializedLexical, // JS_UNINITIALIZED_LEXICAL magic value.
    // Types above are specialized.
    Value,
    SinCosDouble,              // Optimizing a sin/cos to sincos.
    ObjectOrNull,
    None,                      // Invalid, used as a placeholder.
    Slots,                     // A slots vector
    Elements,                  // An elements vector
    Pointer,                   // An opaque pointer that receives no special treatment
    Shape,                     // A Shape pointer.
    ObjectGroup,               // An ObjectGroup pointer.
    Last = ObjectGroup,
    // Representing both SIMD.IntBxN and SIMD.UintBxN.
    Int8x16   = Int32   | (4 << VECTOR_SCALE_SHIFT),
    Int16x8   = Int32   | (3 << VECTOR_SCALE_SHIFT),
    Int32x4   = Int32   | (2 << VECTOR_SCALE_SHIFT),
    Float32x4 = Float32 | (2 << VECTOR_SCALE_SHIFT),
    Bool8x16  = Boolean | (4 << VECTOR_SCALE_SHIFT),
    Bool16x8  = Boolean | (3 << VECTOR_SCALE_SHIFT),
    Bool32x4  = Boolean | (2 << VECTOR_SCALE_SHIFT),
    Doublex2  = Double  | (1 << VECTOR_SCALE_SHIFT)
};

static inline bool
IsSimdType(MIRType type)
{
    return ((unsigned(type) >> VECTOR_SCALE_SHIFT) & VECTOR_SCALE_MASK) != 0;
}

// Returns the number of vector elements (hereby called "length") for a given
// SIMD kind. It is the Y part of the name "Foo x Y".
static inline unsigned
SimdTypeToLength(MIRType type)
{
    MOZ_ASSERT(IsSimdType(type));
    return 1 << ((unsigned(type) >> VECTOR_SCALE_SHIFT) & VECTOR_SCALE_MASK);
}

// Get the type of the individual lanes in a SIMD type.
// For example, Int32x4 -> Int32, Float32x4 -> Float32 etc.
static inline MIRType
SimdTypeToLaneType(MIRType type)
{
    MOZ_ASSERT(IsSimdType(type));
    static_assert(unsigned(MIRType::Last) <= ELEMENT_TYPE_MASK,
                  "ELEMENT_TYPE_MASK should be larger than the last MIRType");
    return MIRType((unsigned(type) >> ELEMENT_TYPE_SHIFT) & ELEMENT_TYPE_MASK);
}

// Get the type expected when inserting a lane into a SIMD type.
// This is the argument type expected by the MSimdValue constructors as well as
// MSimdSplat and MSimdInsertElement.
static inline MIRType
SimdTypeToLaneArgumentType(MIRType type)
{
    MIRType laneType = SimdTypeToLaneType(type);

    // Boolean lanes should be pre-converted to an Int32 with the values 0 or -1.
    // All other lane types are inserted directly.
    return laneType == MIRType::Boolean ? MIRType::Int32 : laneType;
}

static inline MIRType
MIRTypeFromValueType(JSValueType type)
{
    // This function does not deal with magic types. Magic constants should be
    // filtered out in MIRTypeFromValue.
    switch (type) {
      case JSVAL_TYPE_DOUBLE:
        return MIRType::Double;
      case JSVAL_TYPE_INT32:
        return MIRType::Int32;
      case JSVAL_TYPE_UNDEFINED:
        return MIRType::Undefined;
      case JSVAL_TYPE_STRING:
        return MIRType::String;
      case JSVAL_TYPE_SYMBOL:
        return MIRType::Symbol;
      case JSVAL_TYPE_BOOLEAN:
        return MIRType::Boolean;
      case JSVAL_TYPE_NULL:
        return MIRType::Null;
      case JSVAL_TYPE_OBJECT:
        return MIRType::Object;
      case JSVAL_TYPE_UNKNOWN:
        return MIRType::Value;
      default:
        MOZ_CRASH("unexpected jsval type");
    }
}

static inline JSValueType
ValueTypeFromMIRType(MIRType type)
{
  switch (type) {
    case MIRType::Undefined:
      return JSVAL_TYPE_UNDEFINED;
    case MIRType::Null:
      return JSVAL_TYPE_NULL;
    case MIRType::Boolean:
      return JSVAL_TYPE_BOOLEAN;
    case MIRType::Int32:
      return JSVAL_TYPE_INT32;
    case MIRType::Float32: // Fall through, there's no JSVAL for Float32
    case MIRType::Double:
      return JSVAL_TYPE_DOUBLE;
    case MIRType::String:
      return JSVAL_TYPE_STRING;
    case MIRType::Symbol:
      return JSVAL_TYPE_SYMBOL;
    case MIRType::MagicOptimizedArguments:
    case MIRType::MagicOptimizedOut:
    case MIRType::MagicHole:
    case MIRType::MagicIsConstructing:
    case MIRType::MagicUninitializedLexical:
      return JSVAL_TYPE_MAGIC;
    default:
      MOZ_ASSERT(type == MIRType::Object);
      return JSVAL_TYPE_OBJECT;
  }
}

static inline JSValueTag
MIRTypeToTag(MIRType type)
{
    return JSVAL_TYPE_TO_TAG(ValueTypeFromMIRType(type));
}

static inline const char*
StringFromMIRType(MIRType type)
{
  switch (type) {
    case MIRType::Undefined:
      return "Undefined";
    case MIRType::Null:
      return "Null";
    case MIRType::Boolean:
      return "Bool";
    case MIRType::Int32:
      return "Int32";
    case MIRType::Int64:
      return "Int64";
    case MIRType::Double:
      return "Double";
    case MIRType::Float32:
      return "Float32";
    case MIRType::String:
      return "String";
    case MIRType::Symbol:
      return "Symbol";
    case MIRType::Object:
      return "Object";
    case MIRType::MagicOptimizedArguments:
      return "MagicOptimizedArguments";
    case MIRType::MagicOptimizedOut:
      return "MagicOptimizedOut";
    case MIRType::MagicHole:
      return "MagicHole";
    case MIRType::MagicIsConstructing:
      return "MagicIsConstructing";
    case MIRType::MagicUninitializedLexical:
      return "MagicUninitializedLexical";
    case MIRType::Value:
      return "Value";
    case MIRType::SinCosDouble:
      return "SinCosDouble";
    case MIRType::ObjectOrNull:
      return "ObjectOrNull";
    case MIRType::None:
      return "None";
    case MIRType::Slots:
      return "Slots";
    case MIRType::Elements:
      return "Elements";
    case MIRType::Pointer:
      return "Pointer";
    case MIRType::Shape:
      return "Shape";
    case MIRType::ObjectGroup:
      return "ObjectGroup";
    case MIRType::Int32x4:
      return "Int32x4";
    case MIRType::Int16x8:
      return "Int16x8";
    case MIRType::Int8x16:
      return "Int8x16";
    case MIRType::Float32x4:
      return "Float32x4";
    case MIRType::Bool32x4:
      return "Bool32x4";
    case MIRType::Bool16x8:
      return "Bool16x8";
    case MIRType::Bool8x16:
      return "Bool8x16";
    case MIRType::Doublex2:
      return "Doublex2";
  }
  MOZ_CRASH("Unknown MIRType.");
}

static inline bool
IsIntType(MIRType type)
{
    return type == MIRType::Int32 ||
           type == MIRType::Int64;
}

static inline bool
IsNumberType(MIRType type)
{
    return type == MIRType::Int32 ||
           type == MIRType::Double ||
           type == MIRType::Float32 ||
           type == MIRType::Int64;
}

static inline bool
IsTypeRepresentableAsDouble(MIRType type)
{
    return type == MIRType::Int32 ||
           type == MIRType::Double ||
           type == MIRType::Float32;
}

static inline bool
IsFloatType(MIRType type)
{
    return type == MIRType::Int32 || type == MIRType::Float32;
}

static inline bool
IsFloatingPointType(MIRType type)
{
    return type == MIRType::Double || type == MIRType::Float32;
}

static inline bool
IsNullOrUndefined(MIRType type)
{
    return type == MIRType::Null || type == MIRType::Undefined;
}

static inline bool
IsFloatingPointSimdType(MIRType type)
{
    return type == MIRType::Float32x4;
}

static inline bool
IsIntegerSimdType(MIRType type)
{
    return IsSimdType(type) && SimdTypeToLaneType(type) == MIRType::Int32;
}

static inline bool
IsBooleanSimdType(MIRType type)
{
    return IsSimdType(type) && SimdTypeToLaneType(type) == MIRType::Boolean;
}

static inline bool
IsMagicType(MIRType type)
{
    return type == MIRType::MagicHole ||
           type == MIRType::MagicOptimizedOut ||
           type == MIRType::MagicIsConstructing ||
           type == MIRType::MagicOptimizedArguments ||
           type == MIRType::MagicUninitializedLexical;
}

static inline MIRType
ScalarTypeToMIRType(Scalar::Type type)
{
    switch (type) {
      case Scalar::Int8:
      case Scalar::Uint8:
      case Scalar::Int16:
      case Scalar::Uint16:
      case Scalar::Int32:
      case Scalar::Uint32:
      case Scalar::Uint8Clamped:
        return MIRType::Int32;
      case Scalar::Int64:
        return MIRType::Int64;
      case Scalar::Float32:
        return MIRType::Float32;
      case Scalar::Float64:
        return MIRType::Double;
      case Scalar::Float32x4:
        return MIRType::Float32x4;
      case Scalar::Int8x16:
        return MIRType::Int8x16;
      case Scalar::Int16x8:
        return MIRType::Int16x8;
      case Scalar::Int32x4:
        return MIRType::Int32x4;
      case Scalar::MaxTypedArrayViewType:
        break;
    }
    MOZ_CRASH("unexpected SIMD kind");
}

static inline unsigned
ScalarTypeToLength(Scalar::Type type)
{
    switch (type) {
      case Scalar::Int8:
      case Scalar::Uint8:
      case Scalar::Int16:
      case Scalar::Uint16:
      case Scalar::Int32:
      case Scalar::Uint32:
      case Scalar::Int64:
      case Scalar::Float32:
      case Scalar::Float64:
      case Scalar::Uint8Clamped:
        return 1;
      case Scalar::Float32x4:
      case Scalar::Int32x4:
        return 4;
      case Scalar::Int16x8:
        return 8;
      case Scalar::Int8x16:
        return 16;
      case Scalar::MaxTypedArrayViewType:
        break;
    }
    MOZ_CRASH("unexpected SIMD kind");
}

static inline const char*
PropertyNameToExtraName(PropertyName* name)
{
    JS::AutoCheckCannotGC nogc;
    if (!name->hasLatin1Chars())
        return nullptr;
    return reinterpret_cast<const char *>(name->latin1Chars(nogc));
}

#ifdef DEBUG

// Track the pipeline of opcodes which has produced a snapshot.
#define TRACK_SNAPSHOTS 1

// Make sure registers are not modified between an instruction and
// its OsiPoint.
#define CHECK_OSIPOINT_REGISTERS 1

#endif // DEBUG

enum {
    ArgType_General = 0x1,
    ArgType_Double  = 0x2,
    ArgType_Float32 = 0x3,
    ArgType_Int64 = 0x4,

    RetType_Shift   = 0x0,
    ArgType_Shift   = 0x3,
    ArgType_Mask    = 0x7
};

enum ABIFunctionType
{
    // VM functions that take 0-9 non-double arguments
    // and return a non-double value.
    Args_General0 = ArgType_General << RetType_Shift,
    Args_General1 = Args_General0 | (ArgType_General << (ArgType_Shift * 1)),
    Args_General2 = Args_General1 | (ArgType_General << (ArgType_Shift * 2)),
    Args_General3 = Args_General2 | (ArgType_General << (ArgType_Shift * 3)),
    Args_General4 = Args_General3 | (ArgType_General << (ArgType_Shift * 4)),
    Args_General5 = Args_General4 | (ArgType_General << (ArgType_Shift * 5)),
    Args_General6 = Args_General5 | (ArgType_General << (ArgType_Shift * 6)),
    Args_General7 = Args_General6 | (ArgType_General << (ArgType_Shift * 7)),
    Args_General8 = Args_General7 | (ArgType_General << (ArgType_Shift * 8)),

    // int64 f(double)
    Args_Int64_Double = (ArgType_Int64 << RetType_Shift) | (ArgType_Double << ArgType_Shift),

    // double f()
    Args_Double_None = ArgType_Double << RetType_Shift,

    // int f(double)
    Args_Int_Double = Args_General0 | (ArgType_Double << ArgType_Shift),

    // float f(float)
    Args_Float32_Float32 = (ArgType_Float32 << RetType_Shift) | (ArgType_Float32 << ArgType_Shift),

    // double f(double)
    Args_Double_Double = Args_Double_None | (ArgType_Double << ArgType_Shift),

    // double f(int)
    Args_Double_Int = Args_Double_None | (ArgType_General << ArgType_Shift),

    // double f(int, int)
    Args_Double_IntInt = Args_Double_Int | (ArgType_General << (ArgType_Shift * 2)),

    // double f(double, int)
    Args_Double_DoubleInt = Args_Double_None |
        (ArgType_General << (ArgType_Shift * 1)) |
        (ArgType_Double << (ArgType_Shift * 2)),

    // double f(double, double)
    Args_Double_DoubleDouble = Args_Double_Double | (ArgType_Double << (ArgType_Shift * 2)),

    // double f(int, double)
    Args_Double_IntDouble = Args_Double_None |
        (ArgType_Double << (ArgType_Shift * 1)) |
        (ArgType_General << (ArgType_Shift * 2)),

    // int f(int, double)
    Args_Int_IntDouble = Args_General0 |
        (ArgType_Double << (ArgType_Shift * 1)) |
        (ArgType_General << (ArgType_Shift * 2)),

    // double f(double, double, double)
    Args_Double_DoubleDoubleDouble = Args_Double_DoubleDouble | (ArgType_Double << (ArgType_Shift * 3)),

    // double f(double, double, double, double)
    Args_Double_DoubleDoubleDoubleDouble = Args_Double_DoubleDoubleDouble | (ArgType_Double << (ArgType_Shift * 4)),

    // int f(double, int, int)
    Args_Int_DoubleIntInt = Args_General0 |
       (ArgType_General << (ArgType_Shift * 1)) |
       (ArgType_General << (ArgType_Shift * 2)) |
       (ArgType_Double  << (ArgType_Shift * 3)),

    // int f(int, double, int, int)
    Args_Int_IntDoubleIntInt = Args_General0 |
        (ArgType_General << (ArgType_Shift * 1)) |
        (ArgType_General << (ArgType_Shift * 2)) |
        (ArgType_Double  << (ArgType_Shift * 3)) |
        (ArgType_General << (ArgType_Shift * 4))

};

enum class BarrierKind : uint32_t {
    // No barrier is needed.
    NoBarrier,

    // The barrier only has to check the value's type tag is in the TypeSet.
    // Specific object types don't have to be checked.
    TypeTagOnly,

    // Check if the value is in the TypeSet, including the object type if it's
    // an object.
    TypeSet
};

enum ReprotectCode { Reprotect = true, DontReprotect = false };

} // namespace jit
} // namespace js

#endif /* jit_IonTypes_h */