src/compilation-cache.cc - platform/external/chromium_org/v8 - Git at Google

 // Copyright 2011 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 "assembler.h"
 #include "compilation-cache.h"
 #include "serialize.h"

 namespace v8 {
 namespace internal {


 // 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;


 CompilationCache::CompilationCache(Isolate* isolate)
     : isolate_(isolate),
       script_(isolate, kScriptGenerations),
       eval_global_(isolate, kEvalGlobalGenerations),
       eval_contextual_(isolate, kEvalContextualGenerations),
       reg_exp_(isolate, kRegExpGenerations),
       enabled_(true) {
   CompilationSubCache* subcaches[kSubCacheCount] =
     {&script_, &eval_global_, &eval_contextual_, &reg_exp_};
   for (int i = 0; i < kSubCacheCount; ++i) {
     subcaches_[i] = subcaches[i];
   }
 }


 CompilationCache::~CompilationCache() {}


 static Handle<CompilationCacheTable> AllocateTable(Isolate* isolate, int size) {
   CALL_HEAP_FUNCTION(isolate,
                      CompilationCacheTable::Allocate(isolate->heap(), size),
                      CompilationCacheTable);
 }


 Handle<CompilationCacheTable> CompilationSubCache::GetTable(int generation) {
   ASSERT(generation < generations_);
   Handle<CompilationCacheTable> result;
   if (tables_[generation]->IsUndefined()) {
     result = AllocateTable(isolate(), kInitialCacheSize);
     tables_[generation] = *result;
   } else {
     CompilationCacheTable* table =
         CompilationCacheTable::cast(tables_[generation]);
     result = Handle<CompilationCacheTable>(table, isolate());
   }
   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] = isolate()->heap()->undefined_value();
 }


 void CompilationSubCache::IterateFunctions(ObjectVisitor* v) {
   Object* undefined = isolate()->heap()->undefined_value();
   for (int i = 0; i < generations_; i++) {
     if (tables_[i] != undefined) {
       reinterpret_cast<CompilationCacheTable*>(tables_[i])->IterateElements(v);
     }
   }
 }


 void CompilationSubCache::Iterate(ObjectVisitor* v) {
   v->VisitPointers(&tables_[0], &tables_[generations_]);
 }


 void CompilationSubCache::Clear() {
   MemsetPointer(tables_, isolate()->heap()->undefined_value(), generations_);
 }


 void CompilationSubCache::Remove(Handle<SharedFunctionInfo> function_info) {
   // Probe the script generation tables. Make sure not to leak handles
   // into the caller's handle scope.
   { HandleScope scope(isolate());
     for (int generation = 0; generation < generations(); generation++) {
       Handle<CompilationCacheTable> table = GetTable(generation);
       table->Remove(*function_info);
     }
   }
 }


 CompilationCacheScript::CompilationCacheScript(Isolate* isolate,
                                                int generations)
     : CompilationSubCache(isolate, generations),
       script_histogram_(NULL),
       script_histogram_initialized_(false) { }


 // 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<SharedFunctionInfo> function_info,
     Handle<Object> name,
     int line_offset,
     int column_offset,
     bool is_shared_cross_origin) {
   Handle<Script> script =
       Handle<Script>(Script::cast(function_info->script()), isolate());
   // 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;
   // Were both scripts tagged by the embedder as being shared cross-origin?
   if (is_shared_cross_origin != script->is_shared_cross_origin()) 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<SharedFunctionInfo> CompilationCacheScript::Lookup(
     Handle<String> source,
     Handle<Object> name,
     int line_offset,
     int column_offset,
     bool is_shared_cross_origin,
     Handle<Context> context) {
   Object* result = NULL;
   int generation;

   // Probe the script generation tables. Make sure not to leak handles
   // into the caller's handle scope.
   { HandleScope scope(isolate());
     for (generation = 0; generation < generations(); generation++) {
       Handle<CompilationCacheTable> table = GetTable(generation);
       Handle<Object> probe(table->Lookup(*source, *context), isolate());
       if (probe->IsSharedFunctionInfo()) {
         Handle<SharedFunctionInfo> function_info =
             Handle<SharedFunctionInfo>::cast(probe);
         // Break when we've found a suitable shared function info that
         // matches the origin.
         if (HasOrigin(function_info,
                       name,
                       line_offset,
                       column_offset,
                       is_shared_cross_origin)) {
           result = *function_info;
           break;
         }
       }
     }
   }

   if (!script_histogram_initialized_) {
     script_histogram_ = isolate()->stats_table()->CreateHistogram(
         "V8.ScriptCache",
         0,
         kScriptGenerations,
         kScriptGenerations + 1);
     script_histogram_initialized_ = true;
   }

   if (script_histogram_ != NULL) {
     // The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
     isolate()->stats_table()->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<SharedFunctionInfo> shared(SharedFunctionInfo::cast(result),
                                       isolate());
     ASSERT(HasOrigin(shared,
                      name,
                      line_offset,
                      column_offset,
                      is_shared_cross_origin));
     // 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, context, shared);
     isolate()->counters()->compilation_cache_hits()->Increment();
     return shared;
   } else {
     isolate()->counters()->compilation_cache_misses()->Increment();
     return Handle<SharedFunctionInfo>::null();
   }
 }


 MaybeObject* CompilationCacheScript::TryTablePut(
     Handle<String> source,
     Handle<Context> context,
     Handle<SharedFunctionInfo> function_info) {
   Handle<CompilationCacheTable> table = GetFirstTable();
   return table->Put(*source, *context, *function_info);
 }


 Handle<CompilationCacheTable> CompilationCacheScript::TablePut(
     Handle<String> source,
     Handle<Context> context,
     Handle<SharedFunctionInfo> function_info) {
   CALL_HEAP_FUNCTION(isolate(),
                      TryTablePut(source, context, function_info),
                      CompilationCacheTable);
 }


 void CompilationCacheScript::Put(Handle<String> source,
                                  Handle<Context> context,
                                  Handle<SharedFunctionInfo> function_info) {
   HandleScope scope(isolate());
   SetFirstTable(TablePut(source, context, function_info));
 }


 Handle<SharedFunctionInfo> CompilationCacheEval::Lookup(
     Handle<String> source,
     Handle<Context> context,
     LanguageMode language_mode,
     int scope_position) {
   // 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(isolate());
     for (generation = 0; generation < generations(); generation++) {
       Handle<CompilationCacheTable> table = GetTable(generation);
       result = table->LookupEval(
           *source, *context, language_mode, scope_position);
       if (result->IsSharedFunctionInfo()) {
         break;
       }
     }
   }
   if (result->IsSharedFunctionInfo()) {
     Handle<SharedFunctionInfo>
         function_info(SharedFunctionInfo::cast(result), isolate());
     if (generation != 0) {
       Put(source, context, function_info, scope_position);
     }
     isolate()->counters()->compilation_cache_hits()->Increment();
     return function_info;
   } else {
     isolate()->counters()->compilation_cache_misses()->Increment();
     return Handle<SharedFunctionInfo>::null();
   }
 }


 MaybeObject* CompilationCacheEval::TryTablePut(
     Handle<String> source,
     Handle<Context> context,
     Handle<SharedFunctionInfo> function_info,
     int scope_position) {
   Handle<CompilationCacheTable> table = GetFirstTable();
   return table->PutEval(*source, *context, *function_info, scope_position);
 }


 Handle<CompilationCacheTable> CompilationCacheEval::TablePut(
     Handle<String> source,
     Handle<Context> context,
     Handle<SharedFunctionInfo> function_info,
     int scope_position) {
   CALL_HEAP_FUNCTION(isolate(),
                      TryTablePut(
                          source, context, function_info, scope_position),
                      CompilationCacheTable);
 }


 void CompilationCacheEval::Put(Handle<String> source,
                                Handle<Context> context,
                                Handle<SharedFunctionInfo> function_info,
                                int scope_position) {
   HandleScope scope(isolate());
   SetFirstTable(TablePut(source, context, function_info, scope_position));
 }


 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(isolate());
     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), isolate());
     if (generation != 0) {
       Put(source, flags, data);
     }
     isolate()->counters()->compilation_cache_hits()->Increment();
     return data;
   } else {
     isolate()->counters()->compilation_cache_misses()->Increment();
     return Handle<FixedArray>::null();
   }
 }


 MaybeObject* CompilationCacheRegExp::TryTablePut(
     Handle<String> source,
     JSRegExp::Flags flags,
     Handle<FixedArray> data) {
   Handle<CompilationCacheTable> table = GetFirstTable();
   return table->PutRegExp(*source, flags, *data);
 }


 Handle<CompilationCacheTable> CompilationCacheRegExp::TablePut(
     Handle<String> source,
     JSRegExp::Flags flags,
     Handle<FixedArray> data) {
   CALL_HEAP_FUNCTION(isolate(),
                      TryTablePut(source, flags, data),
                      CompilationCacheTable);
 }


 void CompilationCacheRegExp::Put(Handle<String> source,
                                  JSRegExp::Flags flags,
                                  Handle<FixedArray> data) {
   HandleScope scope(isolate());
   SetFirstTable(TablePut(source, flags, data));
 }


 void CompilationCache::Remove(Handle<SharedFunctionInfo> function_info) {
   if (!IsEnabled()) return;

   eval_global_.Remove(function_info);
   eval_contextual_.Remove(function_info);
   script_.Remove(function_info);
 }


 Handle<SharedFunctionInfo> CompilationCache::LookupScript(
     Handle<String> source,
     Handle<Object> name,
     int line_offset,
     int column_offset,
     bool is_shared_cross_origin,
     Handle<Context> context) {
   if (!IsEnabled()) {
     return Handle<SharedFunctionInfo>::null();
   }

   return script_.Lookup(source,
                         name,
                         line_offset,
                         column_offset,
                         is_shared_cross_origin,
                         context);
 }


 Handle<SharedFunctionInfo> CompilationCache::LookupEval(
     Handle<String> source,
     Handle<Context> context,
     bool is_global,
     LanguageMode language_mode,
     int scope_position) {
   if (!IsEnabled()) {
     return Handle<SharedFunctionInfo>::null();
   }

   Handle<SharedFunctionInfo> result;
   if (is_global) {
     result = eval_global_.Lookup(
         source, context, language_mode, scope_position);
   } else {
     ASSERT(scope_position != RelocInfo::kNoPosition);
     result = eval_contextual_.Lookup(
         source, context, language_mode, scope_position);
   }
   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<Context> context,
                                  Handle<SharedFunctionInfo> function_info) {
   if (!IsEnabled()) {
     return;
   }

   script_.Put(source, context, function_info);
 }


 void CompilationCache::PutEval(Handle<String> source,
                                Handle<Context> context,
                                bool is_global,
                                Handle<SharedFunctionInfo> function_info,
                                int scope_position) {
   if (!IsEnabled()) {
     return;
   }

   HandleScope scope(isolate());
   if (is_global) {
     eval_global_.Put(source, context, function_info, scope_position);
   } else {
     ASSERT(scope_position != RelocInfo::kNoPosition);
     eval_contextual_.Put(source, context, function_info, scope_position);
   }
 }


 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::IterateFunctions(ObjectVisitor* v) {
   for (int i = 0; i < kSubCacheCount; i++) {
     subcaches_[i]->IterateFunctions(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
	// Copyright 2011 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 "assembler.h"
	#include "compilation-cache.h"
	#include "serialize.h"

	namespace v8 {
	namespace internal {


	// 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;


	CompilationCache::CompilationCache(Isolate* isolate)
	: isolate_(isolate),
	script_(isolate, kScriptGenerations),
	eval_global_(isolate, kEvalGlobalGenerations),
	eval_contextual_(isolate, kEvalContextualGenerations),
	reg_exp_(isolate, kRegExpGenerations),
	enabled_(true) {
	CompilationSubCache* subcaches[kSubCacheCount] =
	{&script_, &eval_global_, &eval_contextual_, &reg_exp_};
	for (int i = 0; i < kSubCacheCount; ++i) {
	subcaches_[i] = subcaches[i];
	}
	}


	CompilationCache::~CompilationCache() {}


	static Handle<CompilationCacheTable> AllocateTable(Isolate* isolate, int size) {
	CALL_HEAP_FUNCTION(isolate,
	CompilationCacheTable::Allocate(isolate->heap(), size),
	CompilationCacheTable);
	}


	Handle<CompilationCacheTable> CompilationSubCache::GetTable(int generation) {
	ASSERT(generation < generations_);
	Handle<CompilationCacheTable> result;
	if (tables_[generation]->IsUndefined()) {
	result = AllocateTable(isolate(), kInitialCacheSize);
	tables_[generation] = *result;
	} else {
	CompilationCacheTable* table =
	CompilationCacheTable::cast(tables_[generation]);
	result = Handle<CompilationCacheTable>(table, isolate());
	}
	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] = isolate()->heap()->undefined_value();
	}


	void CompilationSubCache::IterateFunctions(ObjectVisitor* v) {
	Object* undefined = isolate()->heap()->undefined_value();
	for (int i = 0; i < generations_; i++) {
	if (tables_[i] != undefined) {
	reinterpret_cast<CompilationCacheTable*>(tables_[i])->IterateElements(v);
	}
	}
	}


	void CompilationSubCache::Iterate(ObjectVisitor* v) {
	v->VisitPointers(&tables_[0], &tables_[generations_]);
	}


	void CompilationSubCache::Clear() {
	MemsetPointer(tables_, isolate()->heap()->undefined_value(), generations_);
	}


	void CompilationSubCache::Remove(Handle<SharedFunctionInfo> function_info) {
	// Probe the script generation tables. Make sure not to leak handles
	// into the caller's handle scope.
	{ HandleScope scope(isolate());
	for (int generation = 0; generation < generations(); generation++) {
	Handle<CompilationCacheTable> table = GetTable(generation);
	table->Remove(*function_info);
	}
	}
	}


	CompilationCacheScript::CompilationCacheScript(Isolate* isolate,
	int generations)
	: CompilationSubCache(isolate, generations),
	script_histogram_(NULL),
	script_histogram_initialized_(false) { }


	// 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<SharedFunctionInfo> function_info,
	Handle<Object> name,
	int line_offset,
	int column_offset,
	bool is_shared_cross_origin) {
	Handle<Script> script =
	Handle<Script>(Script::cast(function_info->script()), isolate());
	// 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;
	// Were both scripts tagged by the embedder as being shared cross-origin?
	if (is_shared_cross_origin != script->is_shared_cross_origin()) 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<SharedFunctionInfo> CompilationCacheScript::Lookup(
	Handle<String> source,
	Handle<Object> name,
	int line_offset,
	int column_offset,
	bool is_shared_cross_origin,
	Handle<Context> context) {
	Object* result = NULL;
	int generation;

	// Probe the script generation tables. Make sure not to leak handles
	// into the caller's handle scope.
	{ HandleScope scope(isolate());
	for (generation = 0; generation < generations(); generation++) {
	Handle<CompilationCacheTable> table = GetTable(generation);
	Handle<Object> probe(table->Lookup(source, context), isolate());
	if (probe->IsSharedFunctionInfo()) {
	Handle<SharedFunctionInfo> function_info =
	Handle<SharedFunctionInfo>::cast(probe);
	// Break when we've found a suitable shared function info that
	// matches the origin.
	if (HasOrigin(function_info,
	name,
	line_offset,
	column_offset,
	is_shared_cross_origin)) {
	result = *function_info;
	break;
	}
	}
	}
	}

	if (!script_histogram_initialized_) {
	script_histogram_ = isolate()->stats_table()->CreateHistogram(
	"V8.ScriptCache",
	0,
	kScriptGenerations,
	kScriptGenerations + 1);
	script_histogram_initialized_ = true;
	}

	if (script_histogram_ != NULL) {
	// The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
	isolate()->stats_table()->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<SharedFunctionInfo> shared(SharedFunctionInfo::cast(result),
	isolate());
	ASSERT(HasOrigin(shared,
	name,
	line_offset,
	column_offset,
	is_shared_cross_origin));
	// 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, context, shared);
	isolate()->counters()->compilation_cache_hits()->Increment();
	return shared;
	} else {
	isolate()->counters()->compilation_cache_misses()->Increment();
	return Handle<SharedFunctionInfo>::null();
	}
	}


	MaybeObject* CompilationCacheScript::TryTablePut(
	Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info) {
	Handle<CompilationCacheTable> table = GetFirstTable();
	return table->Put(source, context, *function_info);
	}


	Handle<CompilationCacheTable> CompilationCacheScript::TablePut(
	Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info) {
	CALL_HEAP_FUNCTION(isolate(),
	TryTablePut(source, context, function_info),
	CompilationCacheTable);
	}


	void CompilationCacheScript::Put(Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info) {
	HandleScope scope(isolate());
	SetFirstTable(TablePut(source, context, function_info));
	}


	Handle<SharedFunctionInfo> CompilationCacheEval::Lookup(
	Handle<String> source,
	Handle<Context> context,
	LanguageMode language_mode,
	int scope_position) {
	// 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(isolate());
	for (generation = 0; generation < generations(); generation++) {
	Handle<CompilationCacheTable> table = GetTable(generation);
	result = table->LookupEval(
	source, context, language_mode, scope_position);
	if (result->IsSharedFunctionInfo()) {
	break;
	}
	}
	}
	if (result->IsSharedFunctionInfo()) {
	Handle<SharedFunctionInfo>
	function_info(SharedFunctionInfo::cast(result), isolate());
	if (generation != 0) {
	Put(source, context, function_info, scope_position);
	}
	isolate()->counters()->compilation_cache_hits()->Increment();
	return function_info;
	} else {
	isolate()->counters()->compilation_cache_misses()->Increment();
	return Handle<SharedFunctionInfo>::null();
	}
	}


	MaybeObject* CompilationCacheEval::TryTablePut(
	Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info,
	int scope_position) {
	Handle<CompilationCacheTable> table = GetFirstTable();
	return table->PutEval(source, context, *function_info, scope_position);
	}


	Handle<CompilationCacheTable> CompilationCacheEval::TablePut(
	Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info,
	int scope_position) {
	CALL_HEAP_FUNCTION(isolate(),
	TryTablePut(
	source, context, function_info, scope_position),
	CompilationCacheTable);
	}


	void CompilationCacheEval::Put(Handle<String> source,
	Handle<Context> context,
	Handle<SharedFunctionInfo> function_info,
	int scope_position) {
	HandleScope scope(isolate());
	SetFirstTable(TablePut(source, context, function_info, scope_position));
	}


	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(isolate());
	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), isolate());
	if (generation != 0) {
	Put(source, flags, data);
	}
	isolate()->counters()->compilation_cache_hits()->Increment();
	return data;
	} else {
	isolate()->counters()->compilation_cache_misses()->Increment();
	return Handle<FixedArray>::null();
	}
	}


	MaybeObject* CompilationCacheRegExp::TryTablePut(
	Handle<String> source,
	JSRegExp::Flags flags,
	Handle<FixedArray> data) {
	Handle<CompilationCacheTable> table = GetFirstTable();
	return table->PutRegExp(source, flags, data);
	}


	Handle<CompilationCacheTable> CompilationCacheRegExp::TablePut(
	Handle<String> source,
	JSRegExp::Flags flags,
	Handle<FixedArray> data) {
	CALL_HEAP_FUNCTION(isolate(),
	TryTablePut(source, flags, data),
	CompilationCacheTable);
	}


	void CompilationCacheRegExp::Put(Handle<String> source,
	JSRegExp::Flags flags,
	Handle<FixedArray> data) {
	HandleScope scope(isolate());
	SetFirstTable(TablePut(source, flags, data));
	}


	void CompilationCache::Remove(Handle<SharedFunctionInfo> function_info) {
	if (!IsEnabled()) return;

	eval_global_.Remove(function_info);
	eval_contextual_.Remove(function_info);
	script_.Remove(function_info);
	}


	Handle<SharedFunctionInfo> CompilationCache::LookupScript(
	Handle<String> source,
	Handle<Object> name,
	int line_offset,
	int column_offset,
	bool is_shared_cross_origin,
	Handle<Context> context) {
	if (!IsEnabled()) {
	return Handle<SharedFunctionInfo>::null();
	}

	return script_.Lookup(source,
	name,
	line_offset,
	column_offset,
	is_shared_cross_origin,
	context);
	}


	Handle<SharedFunctionInfo> CompilationCache::LookupEval(
	Handle<String> source,
	Handle<Context> context,
	bool is_global,
	LanguageMode language_mode,
	int scope_position) {
	if (!IsEnabled()) {
	return Handle<SharedFunctionInfo>::null();
	}

	Handle<SharedFunctionInfo> result;
	if (is_global) {
	result = eval_global_.Lookup(
	source, context, language_mode, scope_position);
	} else {
	ASSERT(scope_position != RelocInfo::kNoPosition);
	result = eval_contextual_.Lookup(
	source, context, language_mode, scope_position);
	}
	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<Context> context,
	Handle<SharedFunctionInfo> function_info) {
	if (!IsEnabled()) {
	return;
	}

	script_.Put(source, context, function_info);
	}


	void CompilationCache::PutEval(Handle<String> source,
	Handle<Context> context,
	bool is_global,
	Handle<SharedFunctionInfo> function_info,
	int scope_position) {
	if (!IsEnabled()) {
	return;
	}

	HandleScope scope(isolate());
	if (is_global) {
	eval_global_.Put(source, context, function_info, scope_position);
	} else {
	ASSERT(scope_position != RelocInfo::kNoPosition);
	eval_contextual_.Put(source, context, function_info, scope_position);
	}
	}



	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::IterateFunctions(ObjectVisitor* v) {
	for (int i = 0; i < kSubCacheCount; i++) {
	subcaches_[i]->IterateFunctions(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