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 148
