112864a83a
for scripts. Review URL: http://codereview.chromium.org/115592 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2052 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
318 lines
11 KiB
C++
318 lines
11 KiB
C++
// Copyright 2008 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "v8.h"
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#include "compilation-cache.h"
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namespace v8 {
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namespace internal {
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enum {
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// The number of script generations tell how many GCs a script can
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// survive in the compilation cache, before it will be flushed if it
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// hasn't been used.
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NUMBER_OF_SCRIPT_GENERATIONS = 8,
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// The compilation cache consists of tables - one for each entry
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// kind plus extras for the script generations.
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NUMBER_OF_TABLE_ENTRIES =
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CompilationCache::LAST_ENTRY + NUMBER_OF_SCRIPT_GENERATIONS
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};
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// Current enable state of the compilation cache.
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static bool enabled = true;
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static inline bool IsEnabled() {
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return FLAG_compilation_cache && enabled;
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}
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// Keep separate tables for the different entry kinds.
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static Object* tables[NUMBER_OF_TABLE_ENTRIES] = { 0, };
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static Handle<CompilationCacheTable> AllocateTable(int size) {
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CALL_HEAP_FUNCTION(CompilationCacheTable::Allocate(size),
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CompilationCacheTable);
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}
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static Handle<CompilationCacheTable> GetTable(int index) {
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ASSERT(index >= 0 && index < NUMBER_OF_TABLE_ENTRIES);
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Handle<CompilationCacheTable> result;
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if (tables[index]->IsUndefined()) {
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static const int kInitialCacheSize = 64;
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result = AllocateTable(kInitialCacheSize);
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tables[index] = *result;
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} else {
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CompilationCacheTable* table = CompilationCacheTable::cast(tables[index]);
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result = Handle<CompilationCacheTable>(table);
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}
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return result;
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}
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static Handle<JSFunction> Lookup(Handle<String> source,
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Handle<Context> context,
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CompilationCache::Entry entry) {
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// Make sure not to leak the table into the surrounding handle
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// scope. Otherwise, we risk keeping old tables around even after
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// having cleared the cache.
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Object* result;
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{ HandleScope scope;
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Handle<CompilationCacheTable> table = GetTable(entry);
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result = table->LookupEval(*source, *context);
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}
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if (result->IsJSFunction()) {
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return Handle<JSFunction>(JSFunction::cast(result));
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} else {
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return Handle<JSFunction>::null();
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}
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}
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static Handle<FixedArray> Lookup(Handle<String> source,
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JSRegExp::Flags flags) {
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// Make sure not to leak the table into the surrounding handle
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// scope. Otherwise, we risk keeping old tables around even after
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// having cleared the cache.
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Object* result;
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{ HandleScope scope;
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Handle<CompilationCacheTable> table = GetTable(CompilationCache::REGEXP);
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result = table->LookupRegExp(*source, flags);
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}
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if (result->IsFixedArray()) {
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return Handle<FixedArray>(FixedArray::cast(result));
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} else {
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return Handle<FixedArray>::null();
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}
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}
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// We only re-use a cached function for some script source code if the
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// script originates from the same place. This is to avoid issues
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// when reporting errors, etc.
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static bool HasOrigin(Handle<JSFunction> boilerplate,
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Handle<Object> name,
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int line_offset,
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int column_offset) {
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Handle<Script> script =
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Handle<Script>(Script::cast(boilerplate->shared()->script()));
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// If the script name isn't set, the boilerplate script should have
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// an undefined name to have the same origin.
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if (name.is_null()) {
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return script->name()->IsUndefined();
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}
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// Do the fast bailout checks first.
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if (line_offset != script->line_offset()->value()) return false;
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if (column_offset != script->column_offset()->value()) return false;
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// Check that both names are strings. If not, no match.
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if (!name->IsString() || !script->name()->IsString()) return false;
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// Compare the two name strings for equality.
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return String::cast(*name)->Equals(String::cast(script->name()));
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}
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// TODO(245): Need to allow identical code from different contexts to
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// be cached in the same script generation. Currently the first use
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// will be cached, but subsequent code from different source / line
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// won't.
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Handle<JSFunction> CompilationCache::LookupScript(Handle<String> source,
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Handle<Object> name,
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int line_offset,
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int column_offset) {
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if (!IsEnabled()) {
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return Handle<JSFunction>::null();
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}
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// Use an int for the generation index, so value range propagation
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// in gcc 4.3+ won't assume it can only go up to LAST_ENTRY when in
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// fact it can go up to SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS.
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int generation = SCRIPT;
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Object* result = NULL;
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// Probe the script generation tables. Make sure not to leak handles
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// into the caller's handle scope.
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{ HandleScope scope;
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while (generation < SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS) {
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Handle<CompilationCacheTable> table = GetTable(generation);
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Handle<Object> probe(table->Lookup(*source));
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if (probe->IsJSFunction()) {
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Handle<JSFunction> boilerplate = Handle<JSFunction>::cast(probe);
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// Break when we've found a suitable boilerplate function that
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// matches the origin.
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if (HasOrigin(boilerplate, name, line_offset, column_offset)) {
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result = *boilerplate;
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break;
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}
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}
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// Go to the next generation.
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generation++;
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}
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}
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static void* script_histogram = StatsTable::CreateHistogram(
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"V8.ScriptCache",
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0,
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NUMBER_OF_SCRIPT_GENERATIONS,
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NUMBER_OF_SCRIPT_GENERATIONS + 1);
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if (script_histogram != NULL) {
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// The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
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StatsTable::AddHistogramSample(script_histogram, generation - SCRIPT);
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}
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// Once outside the manacles of the handle scope, we need to recheck
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// to see if we actually found a cached script. If so, we return a
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// handle created in the caller's handle scope.
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if (result != NULL) {
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Handle<JSFunction> boilerplate(JSFunction::cast(result));
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ASSERT(HasOrigin(boilerplate, name, line_offset, column_offset));
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// If the script was found in a later generation, we promote it to
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// the first generation to let it survive longer in the cache.
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if (generation != SCRIPT) PutScript(source, boilerplate);
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Counters::compilation_cache_hits.Increment();
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return boilerplate;
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} else {
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Counters::compilation_cache_misses.Increment();
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return Handle<JSFunction>::null();
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}
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}
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Handle<JSFunction> CompilationCache::LookupEval(Handle<String> source,
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Handle<Context> context,
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Entry entry) {
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if (!IsEnabled()) {
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return Handle<JSFunction>::null();
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}
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ASSERT(entry == EVAL_GLOBAL || entry == EVAL_CONTEXTUAL);
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Handle<JSFunction> result = Lookup(source, context, entry);
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if (result.is_null()) {
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Counters::compilation_cache_misses.Increment();
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} else {
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Counters::compilation_cache_hits.Increment();
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}
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return result;
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}
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Handle<FixedArray> CompilationCache::LookupRegExp(Handle<String> source,
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JSRegExp::Flags flags) {
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if (!IsEnabled()) {
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return Handle<FixedArray>::null();
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}
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Handle<FixedArray> result = Lookup(source, flags);
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if (result.is_null()) {
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Counters::compilation_cache_misses.Increment();
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} else {
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Counters::compilation_cache_hits.Increment();
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}
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return result;
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}
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void CompilationCache::PutScript(Handle<String> source,
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Handle<JSFunction> boilerplate) {
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if (!IsEnabled()) {
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return;
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}
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HandleScope scope;
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ASSERT(boilerplate->IsBoilerplate());
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Handle<CompilationCacheTable> table = GetTable(SCRIPT);
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CALL_HEAP_FUNCTION_VOID(table->Put(*source, *boilerplate));
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}
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void CompilationCache::PutEval(Handle<String> source,
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Handle<Context> context,
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Entry entry,
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Handle<JSFunction> boilerplate) {
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if (!IsEnabled()) {
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return;
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}
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HandleScope scope;
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ASSERT(boilerplate->IsBoilerplate());
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Handle<CompilationCacheTable> table = GetTable(entry);
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CALL_HEAP_FUNCTION_VOID(table->PutEval(*source, *context, *boilerplate));
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}
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void CompilationCache::PutRegExp(Handle<String> source,
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JSRegExp::Flags flags,
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Handle<FixedArray> data) {
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if (!IsEnabled()) {
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return;
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}
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HandleScope scope;
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Handle<CompilationCacheTable> table = GetTable(REGEXP);
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CALL_HEAP_FUNCTION_VOID(table->PutRegExp(*source, flags, *data));
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}
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void CompilationCache::Clear() {
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for (int i = 0; i < NUMBER_OF_TABLE_ENTRIES; i++) {
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tables[i] = Heap::undefined_value();
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}
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}
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void CompilationCache::Iterate(ObjectVisitor* v) {
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v->VisitPointers(&tables[0], &tables[NUMBER_OF_TABLE_ENTRIES]);
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}
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void CompilationCache::MarkCompactPrologue() {
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ASSERT(LAST_ENTRY == SCRIPT);
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for (int i = NUMBER_OF_TABLE_ENTRIES - 1; i > SCRIPT; i--) {
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tables[i] = tables[i - 1];
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}
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for (int j = 0; j <= LAST_ENTRY; j++) {
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tables[j] = Heap::undefined_value();
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}
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}
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void CompilationCache::Enable() {
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enabled = true;
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}
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void CompilationCache::Disable() {
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enabled = false;
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Clear();
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}
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} } // namespace v8::internal
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