Home | History | Annotate | Download | only in src 
      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #include "elements-kind.h"
     29 
     30 #include "api.h"
     31 #include "elements.h"
     32 #include "objects.h"
     33 
     34 namespace v8 {
     35 namespace internal {
     36 
     37 
     38 const char* ElementsKindToString(ElementsKind kind) {
     39   ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
     40   return accessor->name();
     41 }
     42 
     43 
     44 void PrintElementsKind(FILE* out, ElementsKind kind) {
     45   PrintF(out, "%s", ElementsKindToString(kind));
     46 }
     47 
     48 
     49 ElementsKind GetInitialFastElementsKind() {
     50   if (FLAG_packed_arrays) {
     51     return FAST_SMI_ELEMENTS;
     52   } else {
     53     return FAST_HOLEY_SMI_ELEMENTS;
     54   }
     55 }
     56 
     57 
     58 struct InitializeFastElementsKindSequence {
     59   static void Construct(
     60       ElementsKind** fast_elements_kind_sequence_ptr) {
     61     ElementsKind* fast_elements_kind_sequence =
     62         new ElementsKind[kFastElementsKindCount];
     63     *fast_elements_kind_sequence_ptr = fast_elements_kind_sequence;
     64     STATIC_ASSERT(FAST_SMI_ELEMENTS == FIRST_FAST_ELEMENTS_KIND);
     65     fast_elements_kind_sequence[0] = FAST_SMI_ELEMENTS;
     66     fast_elements_kind_sequence[1] = FAST_HOLEY_SMI_ELEMENTS;
     67     fast_elements_kind_sequence[2] = FAST_DOUBLE_ELEMENTS;
     68     fast_elements_kind_sequence[3] = FAST_HOLEY_DOUBLE_ELEMENTS;
     69     fast_elements_kind_sequence[4] = FAST_ELEMENTS;
     70     fast_elements_kind_sequence[5] = FAST_HOLEY_ELEMENTS;
     71   }
     72 };
     73 
     74 
     75 static LazyInstance<ElementsKind*,
     76                     InitializeFastElementsKindSequence>::type
     77     fast_elements_kind_sequence = LAZY_INSTANCE_INITIALIZER;
     78 
     79 
     80 ElementsKind GetFastElementsKindFromSequenceIndex(int sequence_number) {
     81   ASSERT(sequence_number >= 0 &&
     82          sequence_number < kFastElementsKindCount);
     83   return fast_elements_kind_sequence.Get()[sequence_number];
     84 }
     85 
     86 
     87 int GetSequenceIndexFromFastElementsKind(ElementsKind elements_kind) {
     88   for (int i = 0; i < kFastElementsKindCount; ++i) {
     89     if (fast_elements_kind_sequence.Get()[i] == elements_kind) {
     90       return i;
     91     }
     92   }
     93   UNREACHABLE();
     94   return 0;
     95 }
     96 
     97 
     98 ElementsKind GetNextMoreGeneralFastElementsKind(ElementsKind elements_kind,
     99                                                 bool allow_only_packed) {
    100   ASSERT(IsFastElementsKind(elements_kind));
    101   ASSERT(elements_kind != TERMINAL_FAST_ELEMENTS_KIND);
    102   while (true) {
    103     int index =
    104         GetSequenceIndexFromFastElementsKind(elements_kind) + 1;
    105     elements_kind = GetFastElementsKindFromSequenceIndex(index);
    106     if (!IsFastHoleyElementsKind(elements_kind) || !allow_only_packed) {
    107       return elements_kind;
    108     }
    109   }
    110   UNREACHABLE();
    111   return TERMINAL_FAST_ELEMENTS_KIND;
    112 }
    113 
    114 
    115 bool IsMoreGeneralElementsKindTransition(ElementsKind from_kind,
    116                                          ElementsKind to_kind) {
    117   switch (from_kind) {
    118     case FAST_SMI_ELEMENTS:
    119       return to_kind != FAST_SMI_ELEMENTS;
    120     case FAST_HOLEY_SMI_ELEMENTS:
    121       return to_kind != FAST_SMI_ELEMENTS &&
    122           to_kind != FAST_HOLEY_SMI_ELEMENTS;
    123     case FAST_DOUBLE_ELEMENTS:
    124       return to_kind != FAST_SMI_ELEMENTS &&
    125           to_kind != FAST_HOLEY_SMI_ELEMENTS &&
    126           to_kind != FAST_DOUBLE_ELEMENTS;
    127     case FAST_HOLEY_DOUBLE_ELEMENTS:
    128       return to_kind == FAST_ELEMENTS ||
    129           to_kind == FAST_HOLEY_ELEMENTS;
    130     case FAST_ELEMENTS:
    131       return to_kind == FAST_HOLEY_ELEMENTS;
    132     case FAST_HOLEY_ELEMENTS:
    133       return false;
    134     default:
    135       return false;
    136   }
    137 }
    138 
    139 
    140 } }  // namespace v8::internal
    141