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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/ic/stub-cache.h"
#include "src/ast/ast.h"
#include "src/base/bits.h"
#include "src/type-info.h"
namespace v8 {
namespace internal {
StubCache::StubCache(Isolate* isolate, Code::Kind ic_kind)
: isolate_(isolate), ic_kind_(ic_kind) {}
void StubCache::Initialize() {
DCHECK(base::bits::IsPowerOfTwo32(kPrimaryTableSize));
DCHECK(base::bits::IsPowerOfTwo32(kSecondaryTableSize));
Clear();
}
#ifdef DEBUG
namespace {
bool CommonStubCacheChecks(StubCache* stub_cache, Name* name, Map* map,
Code* code) {
// Validate that the name does not move on scavenge, and that we
// can use identity checks instead of structural equality checks.
DCHECK(!name->GetHeap()->InNewSpace(name));
DCHECK(name->IsUniqueName());
DCHECK(name->HasHashCode());
if (code) {
Code::Flags expected_flags = Code::RemoveHolderFromFlags(
Code::ComputeHandlerFlags(stub_cache->ic_kind()));
Code::Flags flags = Code::RemoveHolderFromFlags(code->flags());
DCHECK_EQ(expected_flags, flags);
DCHECK_EQ(Code::HANDLER, Code::ExtractKindFromFlags(code->flags()));
}
return true;
}
} // namespace
#endif
Code* StubCache::Set(Name* name, Map* map, Code* code) {
DCHECK(CommonStubCacheChecks(this, name, map, code));
// Compute the primary entry.
int primary_offset = PrimaryOffset(name, map);
Entry* primary = entry(primary_, primary_offset);
Code* old_code = primary->value;
// If the primary entry has useful data in it, we retire it to the
// secondary cache before overwriting it.
if (old_code != isolate_->builtins()->builtin(Builtins::kIllegal)) {
Map* old_map = primary->map;
int seed = PrimaryOffset(primary->key, old_map);
int secondary_offset = SecondaryOffset(primary->key, seed);
Entry* secondary = entry(secondary_, secondary_offset);
*secondary = *primary;
}
// Update primary cache.
primary->key = name;
primary->value = code;
primary->map = map;
isolate()->counters()->megamorphic_stub_cache_updates()->Increment();
return code;
}
Code* StubCache::Get(Name* name, Map* map) {
DCHECK(CommonStubCacheChecks(this, name, map, nullptr));
int primary_offset = PrimaryOffset(name, map);
Entry* primary = entry(primary_, primary_offset);
if (primary->key == name && primary->map == map) {
return primary->value;
}
int secondary_offset = SecondaryOffset(name, primary_offset);
Entry* secondary = entry(secondary_, secondary_offset);
if (secondary->key == name && secondary->map == map) {
return secondary->value;
}
return NULL;
}
void StubCache::Clear() {
Code* empty = isolate_->builtins()->builtin(Builtins::kIllegal);
for (int i = 0; i < kPrimaryTableSize; i++) {
primary_[i].key = isolate()->heap()->empty_string();
primary_[i].map = NULL;
primary_[i].value = empty;
}
for (int j = 0; j < kSecondaryTableSize; j++) {
secondary_[j].key = isolate()->heap()->empty_string();
secondary_[j].map = NULL;
secondary_[j].value = empty;
}
}
void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
Handle<Context> native_context,
Zone* zone) {
for (int i = 0; i < kPrimaryTableSize; i++) {
if (primary_[i].key == *name) {
Map* map = primary_[i].map;
// Map can be NULL, if the stub is constant function call
// with a primitive receiver.
if (map == NULL) continue;
int offset = PrimaryOffset(*name, map);
if (entry(primary_, offset) == &primary_[i] &&
TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
types->AddMapIfMissing(Handle<Map>(map), zone);
}
}
}
for (int i = 0; i < kSecondaryTableSize; i++) {
if (secondary_[i].key == *name) {
Map* map = secondary_[i].map;
// Map can be NULL, if the stub is constant function call
// with a primitive receiver.
if (map == NULL) continue;
// Lookup in primary table and skip duplicates.
int primary_offset = PrimaryOffset(*name, map);
// Lookup in secondary table and add matches.
int offset = SecondaryOffset(*name, primary_offset);
if (entry(secondary_, offset) == &secondary_[i] &&
TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
types->AddMapIfMissing(Handle<Map>(map), zone);
}
}
}
}
} // namespace internal
} // namespace v8
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