Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2012 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 | #include "src/v8.h" |
| 6 | |
| 7 | #include "src/base/bits.h" |
| 8 | #include "src/ic/stub-cache.h" |
| 9 | #include "src/type-info.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | |
| 15 | StubCache::StubCache(Isolate* isolate) : isolate_(isolate) {} |
| 16 | |
| 17 | |
| 18 | void StubCache::Initialize() { |
| 19 | DCHECK(base::bits::IsPowerOfTwo32(kPrimaryTableSize)); |
| 20 | DCHECK(base::bits::IsPowerOfTwo32(kSecondaryTableSize)); |
| 21 | Clear(); |
| 22 | } |
| 23 | |
| 24 | |
| 25 | static Code::Flags CommonStubCacheChecks(Name* name, Map* map, |
| 26 | Code::Flags flags) { |
| 27 | flags = Code::RemoveTypeAndHolderFromFlags(flags); |
| 28 | |
| 29 | // Validate that the name does not move on scavenge, and that we |
| 30 | // can use identity checks instead of structural equality checks. |
| 31 | DCHECK(!name->GetHeap()->InNewSpace(name)); |
| 32 | DCHECK(name->IsUniqueName()); |
| 33 | |
| 34 | // The state bits are not important to the hash function because the stub |
| 35 | // cache only contains handlers. Make sure that the bits are the least |
| 36 | // significant so they will be the ones masked out. |
| 37 | DCHECK_EQ(Code::HANDLER, Code::ExtractKindFromFlags(flags)); |
| 38 | STATIC_ASSERT((Code::ICStateField::kMask & 1) == 1); |
| 39 | |
| 40 | // Make sure that the code type and cache holder are not included in the hash. |
| 41 | DCHECK(Code::ExtractTypeFromFlags(flags) == 0); |
| 42 | DCHECK(Code::ExtractCacheHolderFromFlags(flags) == 0); |
| 43 | |
| 44 | return flags; |
| 45 | } |
| 46 | |
| 47 | |
| 48 | Code* StubCache::Set(Name* name, Map* map, Code* code) { |
| 49 | Code::Flags flags = CommonStubCacheChecks(name, map, code->flags()); |
| 50 | |
| 51 | // Compute the primary entry. |
| 52 | int primary_offset = PrimaryOffset(name, flags, map); |
| 53 | Entry* primary = entry(primary_, primary_offset); |
| 54 | Code* old_code = primary->value; |
| 55 | |
| 56 | // If the primary entry has useful data in it, we retire it to the |
| 57 | // secondary cache before overwriting it. |
| 58 | if (old_code != isolate_->builtins()->builtin(Builtins::kIllegal)) { |
| 59 | Map* old_map = primary->map; |
| 60 | Code::Flags old_flags = |
| 61 | Code::RemoveTypeAndHolderFromFlags(old_code->flags()); |
| 62 | int seed = PrimaryOffset(primary->key, old_flags, old_map); |
| 63 | int secondary_offset = SecondaryOffset(primary->key, old_flags, seed); |
| 64 | Entry* secondary = entry(secondary_, secondary_offset); |
| 65 | *secondary = *primary; |
| 66 | } |
| 67 | |
| 68 | // Update primary cache. |
| 69 | primary->key = name; |
| 70 | primary->value = code; |
| 71 | primary->map = map; |
| 72 | isolate()->counters()->megamorphic_stub_cache_updates()->Increment(); |
| 73 | return code; |
| 74 | } |
| 75 | |
| 76 | |
| 77 | Code* StubCache::Get(Name* name, Map* map, Code::Flags flags) { |
| 78 | flags = CommonStubCacheChecks(name, map, flags); |
| 79 | int primary_offset = PrimaryOffset(name, flags, map); |
| 80 | Entry* primary = entry(primary_, primary_offset); |
| 81 | if (primary->key == name && primary->map == map) { |
| 82 | return primary->value; |
| 83 | } |
| 84 | int secondary_offset = SecondaryOffset(name, flags, primary_offset); |
| 85 | Entry* secondary = entry(secondary_, secondary_offset); |
| 86 | if (secondary->key == name && secondary->map == map) { |
| 87 | return secondary->value; |
| 88 | } |
| 89 | return NULL; |
| 90 | } |
| 91 | |
| 92 | |
| 93 | void StubCache::Clear() { |
| 94 | Code* empty = isolate_->builtins()->builtin(Builtins::kIllegal); |
| 95 | for (int i = 0; i < kPrimaryTableSize; i++) { |
| 96 | primary_[i].key = isolate()->heap()->empty_string(); |
| 97 | primary_[i].map = NULL; |
| 98 | primary_[i].value = empty; |
| 99 | } |
| 100 | for (int j = 0; j < kSecondaryTableSize; j++) { |
| 101 | secondary_[j].key = isolate()->heap()->empty_string(); |
| 102 | secondary_[j].map = NULL; |
| 103 | secondary_[j].value = empty; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | |
| 108 | void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name, |
| 109 | Code::Flags flags, |
| 110 | Handle<Context> native_context, |
| 111 | Zone* zone) { |
| 112 | for (int i = 0; i < kPrimaryTableSize; i++) { |
| 113 | if (primary_[i].key == *name) { |
| 114 | Map* map = primary_[i].map; |
| 115 | // Map can be NULL, if the stub is constant function call |
| 116 | // with a primitive receiver. |
| 117 | if (map == NULL) continue; |
| 118 | |
| 119 | int offset = PrimaryOffset(*name, flags, map); |
| 120 | if (entry(primary_, offset) == &primary_[i] && |
| 121 | !TypeFeedbackOracle::CanRetainOtherContext(map, *native_context)) { |
| 122 | types->AddMapIfMissing(Handle<Map>(map), zone); |
| 123 | } |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | for (int i = 0; i < kSecondaryTableSize; i++) { |
| 128 | if (secondary_[i].key == *name) { |
| 129 | Map* map = secondary_[i].map; |
| 130 | // Map can be NULL, if the stub is constant function call |
| 131 | // with a primitive receiver. |
| 132 | if (map == NULL) continue; |
| 133 | |
| 134 | // Lookup in primary table and skip duplicates. |
| 135 | int primary_offset = PrimaryOffset(*name, flags, map); |
| 136 | |
| 137 | // Lookup in secondary table and add matches. |
| 138 | int offset = SecondaryOffset(*name, flags, primary_offset); |
| 139 | if (entry(secondary_, offset) == &secondary_[i] && |
| 140 | !TypeFeedbackOracle::CanRetainOtherContext(map, *native_context)) { |
| 141 | types->AddMapIfMissing(Handle<Map>(map), zone); |
| 142 | } |
| 143 | } |
| 144 | } |
| 145 | } |
| 146 | } |
| 147 | } // namespace v8::internal |