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