Home | History | Annotate | Download | only in src 
      1 // Copyright 2014 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_FIELD_INDEX_INL_H_
      6 #define V8_FIELD_INDEX_INL_H_
      7 
      8 #include "src/field-index.h"
      9 
     10 namespace v8 {
     11 namespace internal {
     12 
     13 
     14 inline FieldIndex FieldIndex::ForInObjectOffset(int offset, Map* map) {
     15   DCHECK((offset % kPointerSize) == 0);
     16   int index = offset / kPointerSize;
     17   DCHECK(map == NULL ||
     18          index < (map->GetInObjectPropertyOffset(0) / kPointerSize +
     19                   map->GetInObjectProperties()));
     20   return FieldIndex(true, index, false, 0, 0, true);
     21 }
     22 
     23 
     24 inline FieldIndex FieldIndex::ForPropertyIndex(Map* map,
     25                                                int property_index,
     26                                                bool is_double) {
     27   DCHECK(map->instance_type() >= FIRST_NONSTRING_TYPE);
     28   int inobject_properties = map->GetInObjectProperties();
     29   bool is_inobject = property_index < inobject_properties;
     30   int first_inobject_offset;
     31   if (is_inobject) {
     32     first_inobject_offset = map->GetInObjectPropertyOffset(0);
     33   } else {
     34     first_inobject_offset = FixedArray::kHeaderSize;
     35     property_index -= inobject_properties;
     36   }
     37   return FieldIndex(is_inobject,
     38                     property_index + first_inobject_offset / kPointerSize,
     39                     is_double, inobject_properties, first_inobject_offset);
     40 }
     41 
     42 
     43 // Takes an index as computed by GetLoadFieldByIndex and reconstructs a
     44 // FieldIndex object from it.
     45 inline FieldIndex FieldIndex::ForLoadByFieldIndex(Map* map, int orig_index) {
     46   int field_index = orig_index;
     47   int is_inobject = true;
     48   bool is_double = field_index & 1;
     49   int first_inobject_offset = 0;
     50   field_index >>= 1;
     51   if (field_index < 0) {
     52     field_index = -(field_index + 1);
     53     is_inobject = false;
     54     first_inobject_offset = FixedArray::kHeaderSize;
     55     field_index += FixedArray::kHeaderSize / kPointerSize;
     56   } else {
     57     first_inobject_offset = map->GetInObjectPropertyOffset(0);
     58     field_index += JSObject::kHeaderSize / kPointerSize;
     59   }
     60   FieldIndex result(is_inobject, field_index, is_double,
     61                     map->GetInObjectProperties(), first_inobject_offset);
     62   DCHECK(result.GetLoadByFieldIndex() == orig_index);
     63   return result;
     64 }
     65 
     66 
     67 // Returns the index format accepted by the HLoadFieldByIndex instruction.
     68 // (In-object: zero-based from (object start + JSObject::kHeaderSize),
     69 // out-of-object: zero-based from FixedArray::kHeaderSize.)
     70 inline int FieldIndex::GetLoadByFieldIndex() const {
     71   // For efficiency, the LoadByFieldIndex instruction takes an index that is
     72   // optimized for quick access. If the property is inline, the index is
     73   // positive. If it's out-of-line, the encoded index is -raw_index - 1 to
     74   // disambiguate the zero out-of-line index from the zero inobject case.
     75   // The index itself is shifted up by one bit, the lower-most bit
     76   // signifying if the field is a mutable double box (1) or not (0).
     77   int result = index();
     78   if (is_inobject()) {
     79     result -= JSObject::kHeaderSize / kPointerSize;
     80   } else {
     81     result -= FixedArray::kHeaderSize / kPointerSize;
     82     result = -result - 1;
     83   }
     84   result <<= 1;
     85   return is_double() ? (result | 1) : result;
     86 }
     87 
     88 
     89 inline FieldIndex FieldIndex::ForDescriptor(Map* map, int descriptor_index) {
     90   PropertyDetails details =
     91       map->instance_descriptors()->GetDetails(descriptor_index);
     92   int field_index = details.field_index();
     93   return ForPropertyIndex(map, field_index,
     94                           details.representation().IsDouble());
     95 }
     96 
     97 
     98 inline FieldIndex FieldIndex::ForKeyedLookupCacheIndex(Map* map, int index) {
     99   if (FLAG_compiled_keyed_generic_loads) {
    100     return ForLoadByFieldIndex(map, index);
    101   } else {
    102     return ForPropertyIndex(map, index);
    103   }
    104 }
    105 
    106 
    107 inline FieldIndex FieldIndex::FromFieldAccessStubKey(int key) {
    108   return FieldIndex(key);
    109 }
    110 
    111 
    112 inline int FieldIndex::GetKeyedLookupCacheIndex() const {
    113   if (FLAG_compiled_keyed_generic_loads) {
    114     return GetLoadByFieldIndex();
    115   } else {
    116     return property_index();
    117   }
    118 }
    119 
    120 
    121 }  // namespace internal
    122 }  // namespace v8
    123 
    124 #endif
    125