// Copyright 2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "compilation-cache.h"
#include "serialize.h"
namespace v8 {
namespace internal {
// The number of sub caches covering the different types to cache.
static const int kSubCacheCount = 4;
// The number of generations for each sub cache.
// The number of ScriptGenerations is carefully chosen based on histograms.
// See issue 458: http://code.google.com/p/v8/issues/detail?id=458
static const int kScriptGenerations = 5;
static const int kEvalGlobalGenerations = 2;
static const int kEvalContextualGenerations = 2;
static const int kRegExpGenerations = 2;
// Initial size of each compilation cache table allocated.
static const int kInitialCacheSize = 64;
// The compilation cache consists of several generational sub-caches which uses
// this class as a base class. A sub-cache contains a compilation cache tables
// for each generation of the sub-cache. Since the same source code string has
// different compiled code for scripts and evals, we use separate sub-caches
// for different compilation modes, to avoid retrieving the wrong result.
class CompilationSubCache {
public:
explicit CompilationSubCache(int generations): generations_(generations) {
tables_ = NewArray<Object*>(generations);
}
~CompilationSubCache() { DeleteArray(tables_); }
// Get the compilation cache tables for a specific generation.
Handle<CompilationCacheTable> GetTable(int generation);
// Age the sub-cache by evicting the oldest generation and creating a new
// young generation.
void Age();
// GC support.
void Iterate(ObjectVisitor* v);
// Clear this sub-cache evicting all its content.
void Clear();
// Number of generations in this sub-cache.
inline int generations() { return generations_; }
private:
int generations_; // Number of generations.
Object** tables_; // Compilation cache tables - one for each generation.
DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationSubCache);
};
// Sub-cache for scripts.
class CompilationCacheScript : public CompilationSubCache {
public:
explicit CompilationCacheScript(int generations)
: CompilationSubCache(generations) { }
Handle<JSFunction> Lookup(Handle<String> source,
Handle<Object> name,
int line_offset,
int column_offset);
void Put(Handle<String> source, Handle<JSFunction> boilerplate);
private:
bool HasOrigin(Handle<JSFunction> boilerplate,
Handle<Object> name,
int line_offset,
int column_offset);
DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheScript);
};
// Sub-cache for eval scripts.
class CompilationCacheEval: public CompilationSubCache {
public:
explicit CompilationCacheEval(int generations)
: CompilationSubCache(generations) { }
Handle<JSFunction> Lookup(Handle<String> source, Handle<Context> context);
void Put(Handle<String> source,
Handle<Context> context,
Handle<JSFunction> boilerplate);
DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheEval);
};
// Sub-cache for regular expressions.
class CompilationCacheRegExp: public CompilationSubCache {
public:
explicit CompilationCacheRegExp(int generations)
: CompilationSubCache(generations) { }
Handle<FixedArray> Lookup(Handle<String> source, JSRegExp::Flags flags);
void Put(Handle<String> source,
JSRegExp::Flags flags,
Handle<FixedArray> data);
DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheRegExp);
};
// Statically allocate all the sub-caches.
static CompilationCacheScript script(kScriptGenerations);
static CompilationCacheEval eval_global(kEvalGlobalGenerations);
static CompilationCacheEval eval_contextual(kEvalContextualGenerations);
static CompilationCacheRegExp reg_exp(kRegExpGenerations);
static CompilationSubCache* subcaches[kSubCacheCount] =
{&script, &eval_global, &eval_contextual, ®_exp};
// Current enable state of the compilation cache.
static bool enabled = true;
static inline bool IsEnabled() {
return FLAG_compilation_cache && enabled;
}
static Handle<CompilationCacheTable> AllocateTable(int size) {
CALL_HEAP_FUNCTION(CompilationCacheTable::Allocate(size),
CompilationCacheTable);
}
Handle<CompilationCacheTable> CompilationSubCache::GetTable(int generation) {
ASSERT(generation < generations_);
Handle<CompilationCacheTable> result;
if (tables_[generation]->IsUndefined()) {
result = AllocateTable(kInitialCacheSize);
tables_[generation] = *result;
} else {
CompilationCacheTable* table =
CompilationCacheTable::cast(tables_[generation]);
result = Handle<CompilationCacheTable>(table);
}
return result;
}
void CompilationSubCache::Age() {
// Age the generations implicitly killing off the oldest.
for (int i = generations_ - 1; i > 0; i--) {
tables_[i] = tables_[i - 1];
}
// Set the first generation as unborn.
tables_[0] = Heap::undefined_value();
}
void CompilationSubCache::Iterate(ObjectVisitor* v) {
v->VisitPointers(&tables_[0], &tables_[generations_]);
}
void CompilationSubCache::Clear() {
for (int i = 0; i < generations_; i++) {
tables_[i] = Heap::undefined_value();
}
}
// We only re-use a cached function for some script source code if the
// script originates from the same place. This is to avoid issues
// when reporting errors, etc.
bool CompilationCacheScript::HasOrigin(Handle<JSFunction> boilerplate,
Handle<Object> name,
int line_offset,
int column_offset) {
Handle<Script> script =
Handle<Script>(Script::cast(boilerplate->shared()->script()));
// If the script name isn't set, the boilerplate script should have
// an undefined name to have the same origin.
if (name.is_null()) {
return script->name()->IsUndefined();
}
// Do the fast bailout checks first.
if (line_offset != script->line_offset()->value()) return false;
if (column_offset != script->column_offset()->value()) return false;
// Check that both names are strings. If not, no match.
if (!name->IsString() || !script->name()->IsString()) return false;
// Compare the two name strings for equality.
return String::cast(*name)->Equals(String::cast(script->name()));
}
// TODO(245): Need to allow identical code from different contexts to
// be cached in the same script generation. Currently the first use
// will be cached, but subsequent code from different source / line
// won't.
Handle<JSFunction> CompilationCacheScript::Lookup(Handle<String> source,
Handle<Object> name,
int line_offset,
int column_offset) {
Object* result = NULL;
int generation;
// Probe the script generation tables. Make sure not to leak handles
// into the caller's handle scope.
{ HandleScope scope;
for (generation = 0; generation < generations(); generation++) {
Handle<CompilationCacheTable> table = GetTable(generation);
Handle<Object> probe(table->Lookup(*source));
if (probe->IsJSFunction()) {
Handle<JSFunction> boilerplate = Handle<JSFunction>::cast(probe);
// Break when we've found a suitable boilerplate function that
// matches the origin.
if (HasOrigin(boilerplate, name, line_offset, column_offset)) {
result = *boilerplate;
break;
}
}
}
}
static void* script_histogram = StatsTable::CreateHistogram(
"V8.ScriptCache",
0,
kScriptGenerations,
kScriptGenerations + 1);
if (script_histogram != NULL) {
// The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
StatsTable::AddHistogramSample(script_histogram, generation);
}
// Once outside the manacles of the handle scope, we need to recheck
// to see if we actually found a cached script. If so, we return a
// handle created in the caller's handle scope.
if (result != NULL) {
Handle<JSFunction> boilerplate(JSFunction::cast(result));
ASSERT(HasOrigin(boilerplate, name, line_offset, column_offset));
// If the script was found in a later generation, we promote it to
// the first generation to let it survive longer in the cache.
if (generation != 0) Put(source, boilerplate);
Counters::compilation_cache_hits.Increment();
return boilerplate;
} else {
Counters::compilation_cache_misses.Increment();
return Handle<JSFunction>::null();
}
}
void CompilationCacheScript::Put(Handle<String> source,
Handle<JSFunction> boilerplate) {
HandleScope scope;
ASSERT(boilerplate->IsBoilerplate());
Handle<CompilationCacheTable> table = GetTable(0);
CALL_HEAP_FUNCTION_VOID(table->Put(*source, *boilerplate));
}
Handle<JSFunction> CompilationCacheEval::Lookup(Handle<String> source,
Handle<Context> context) {
// Make sure not to leak the table into the surrounding handle
// scope. Otherwise, we risk keeping old tables around even after
// having cleared the cache.
Object* result = NULL;
int generation;
{ HandleScope scope;
for (generation = 0; generation < generations(); generation++) {
Handle<CompilationCacheTable> table = GetTable(generation);
result = table->LookupEval(*source, *context);
if (result->IsJSFunction()) {
break;
}
}
}
if (result->IsJSFunction()) {
Handle<JSFunction> boilerplate(JSFunction::cast(result));
if (generation != 0) {
Put(source, context, boilerplate);
}
Counters::compilation_cache_hits.Increment();
return boilerplate;
} else {
Counters::compilation_cache_misses.Increment();
return Handle<JSFunction>::null();
}
}
void CompilationCacheEval::Put(Handle<String> source,
Handle<Context> context,
Handle<JSFunction> boilerplate) {
HandleScope scope;
ASSERT(boilerplate->IsBoilerplate());
Handle<CompilationCacheTable> table = GetTable(0);
CALL_HEAP_FUNCTION_VOID(table->PutEval(*source, *context, *boilerplate));
}
Handle<FixedArray> CompilationCacheRegExp::Lookup(Handle<String> source,
JSRegExp::Flags flags) {
// Make sure not to leak the table into the surrounding handle
// scope. Otherwise, we risk keeping old tables around even after
// having cleared the cache.
Object* result = NULL;
int generation;
{ HandleScope scope;
for (generation = 0; generation < generations(); generation++) {
Handle<CompilationCacheTable> table = GetTable(generation);
result = table->LookupRegExp(*source, flags);
if (result->IsFixedArray()) {
break;
}
}
}
if (result->IsFixedArray()) {
Handle<FixedArray> data(FixedArray::cast(result));
if (generation != 0) {
Put(source, flags, data);
}
Counters::compilation_cache_hits.Increment();
return data;
} else {
Counters::compilation_cache_misses.Increment();
return Handle<FixedArray>::null();
}
}
void CompilationCacheRegExp::Put(Handle<String> source,
JSRegExp::Flags flags,
Handle<FixedArray> data) {
HandleScope scope;
Handle<CompilationCacheTable> table = GetTable(0);
CALL_HEAP_FUNCTION_VOID(table->PutRegExp(*source, flags, *data));
}
Handle<JSFunction> CompilationCache::LookupScript(Handle<String> source,
Handle<Object> name,
int line_offset,
int column_offset) {
if (!IsEnabled()) {
return Handle<JSFunction>::null();
}
return script.Lookup(source, name, line_offset, column_offset);
}
Handle<JSFunction> CompilationCache::LookupEval(Handle<String> source,
Handle<Context> context,
bool is_global) {
if (!IsEnabled()) {
return Handle<JSFunction>::null();
}
Handle<JSFunction> result;
if (is_global) {
result = eval_global.Lookup(source, context);
} else {
result = eval_contextual.Lookup(source, context);
}
return result;
}
Handle<FixedArray> CompilationCache::LookupRegExp(Handle<String> source,
JSRegExp::Flags flags) {
if (!IsEnabled()) {
return Handle<FixedArray>::null();
}
return reg_exp.Lookup(source, flags);
}
void CompilationCache::PutScript(Handle<String> source,
Handle<JSFunction> boilerplate) {
if (!IsEnabled()) {
return;
}
ASSERT(boilerplate->IsBoilerplate());
script.Put(source, boilerplate);
}
void CompilationCache::PutEval(Handle<String> source,
Handle<Context> context,
bool is_global,
Handle<JSFunction> boilerplate) {
if (!IsEnabled()) {
return;
}
HandleScope scope;
ASSERT(boilerplate->IsBoilerplate());
if (is_global) {
eval_global.Put(source, context, boilerplate);
} else {
eval_contextual.Put(source, context, boilerplate);
}
}
void CompilationCache::PutRegExp(Handle<String> source,
JSRegExp::Flags flags,
Handle<FixedArray> data) {
if (!IsEnabled()) {
return;
}
reg_exp.Put(source, flags, data);
}
void CompilationCache::Clear() {
for (int i = 0; i < kSubCacheCount; i++) {
subcaches[i]->Clear();
}
}
void CompilationCache::Iterate(ObjectVisitor* v) {
for (int i = 0; i < kSubCacheCount; i++) {
subcaches[i]->Iterate(v);
}
}
void CompilationCache::MarkCompactPrologue() {
for (int i = 0; i < kSubCacheCount; i++) {
subcaches[i]->Age();
}
}
void CompilationCache::Enable() {
enabled = true;
}
void CompilationCache::Disable() {
enabled = false;
Clear();
}
} } // namespace v8::internal