IndexingType.h   [plain text]

/*
 * Copyright (C) 2012, 2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef IndexingType_h
#define IndexingType_h

#include "SpeculatedType.h"
#include <wtf/StdLibExtras.h>

namespace JSC {

/*
    Structure of the IndexingType
    =============================
    Conceptually, the IndexingType looks like this:

    struct IndexingType {
        uint8_t isArray:1;                    // bit 0
        uint8_t shape:4;                      // bit 1 - 3
        uint8_t mayHaveIndexedAccessors:1;    // bit 4
    };

    The shape values (e.g. Int32Shape, ContiguousShape, etc) are an enumeration of
    various shapes (though not necessarily sequential in terms of their values).
    Hence, shape values are not bitwise exclusive with respect to each other.
*/

typedef uint8_t IndexingType;

// Flags for testing the presence of capabilities.
static const IndexingType IsArray                  = 0x01;

// The shape of the indexed property storage.
static const IndexingType IndexingShapeMask        = 0x0E;
static const IndexingType NoIndexingShape          = 0x00;
static const IndexingType UndecidedShape           = 0x02; // Only useful for arrays.
static const IndexingType Int32Shape               = 0x04;
static const IndexingType DoubleShape              = 0x06;
static const IndexingType ContiguousShape          = 0x08;
static const IndexingType ArrayStorageShape        = 0x0A;
static const IndexingType SlowPutArrayStorageShape = 0x0C;

static const IndexingType IndexingShapeShift       = 1;
static const IndexingType NumberOfIndexingShapes   = 7;

// Additional flags for tracking the history of the type. These are usually
// masked off unless you ask for them directly.
static const IndexingType MayHaveIndexedAccessors  = 0x10;

// List of acceptable array types.
static const IndexingType NonArray                        = 0x0;
static const IndexingType NonArrayWithInt32               = Int32Shape;
static const IndexingType NonArrayWithDouble              = DoubleShape;
static const IndexingType NonArrayWithContiguous          = ContiguousShape;
static const IndexingType NonArrayWithArrayStorage        = ArrayStorageShape;
static const IndexingType NonArrayWithSlowPutArrayStorage = SlowPutArrayStorageShape;
static const IndexingType ArrayClass                      = IsArray; // I'd want to call this "Array" but this would lead to disastrous namespace pollution.
static const IndexingType ArrayWithUndecided              = IsArray | UndecidedShape;
static const IndexingType ArrayWithInt32                  = IsArray | Int32Shape;
static const IndexingType ArrayWithDouble                 = IsArray | DoubleShape;
static const IndexingType ArrayWithContiguous             = IsArray | ContiguousShape;
static const IndexingType ArrayWithArrayStorage           = IsArray | ArrayStorageShape;
static const IndexingType ArrayWithSlowPutArrayStorage    = IsArray | SlowPutArrayStorageShape;

#define ALL_BLANK_INDEXING_TYPES \
    NonArray:                    \
    case ArrayClass

#define ALL_UNDECIDED_INDEXING_TYPES \
    ArrayWithUndecided

#define ALL_INT32_INDEXING_TYPES      \
    NonArrayWithInt32:                \
    case ArrayWithInt32

#define ALL_DOUBLE_INDEXING_TYPES     \
    NonArrayWithDouble:               \
    case ArrayWithDouble

#define ALL_CONTIGUOUS_INDEXING_TYPES \
    NonArrayWithContiguous:           \
    case ArrayWithContiguous

#define ARRAY_WITH_ARRAY_STORAGE_INDEXING_TYPES \
    ArrayWithArrayStorage:                      \
    case ArrayWithSlowPutArrayStorage
    
#define ALL_ARRAY_STORAGE_INDEXING_TYPES                \
    NonArrayWithArrayStorage:                           \
    case NonArrayWithSlowPutArrayStorage:               \
    case ARRAY_WITH_ARRAY_STORAGE_INDEXING_TYPES

static inline bool hasIndexedProperties(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) != NoIndexingShape;
}

static inline bool hasUndecided(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == UndecidedShape;
}

static inline bool hasInt32(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == Int32Shape;
}

static inline bool hasDouble(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == DoubleShape;
}

static inline bool hasContiguous(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == ContiguousShape;
}

static inline bool hasArrayStorage(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == ArrayStorageShape;
}

static inline bool hasAnyArrayStorage(IndexingType indexingType)
{
    return static_cast<uint8_t>(indexingType & IndexingShapeMask) >= ArrayStorageShape;
}

static inline bool shouldUseSlowPut(IndexingType indexingType)
{
    return (indexingType & IndexingShapeMask) == SlowPutArrayStorageShape;
}

// Return an indexing type that can handle all of the elements of both indexing types.
IndexingType leastUpperBoundOfIndexingTypes(IndexingType, IndexingType);

IndexingType leastUpperBoundOfIndexingTypeAndType(IndexingType, SpeculatedType);
IndexingType leastUpperBoundOfIndexingTypeAndValue(IndexingType, JSValue);

void dumpIndexingType(PrintStream&, IndexingType);
MAKE_PRINT_ADAPTOR(IndexingTypeDump, IndexingType, dumpIndexingType);

// Mask of all possible types.
static const IndexingType AllArrayTypes            = IndexingShapeMask | IsArray;

// Mask of all possible types including the history.
static const IndexingType AllArrayTypesAndHistory  = AllArrayTypes | MayHaveIndexedAccessors;

} // namespace JSC

#endif // IndexingType_h