V8Binding/v8/src/compilation-cache.cc - platform/external/webkit - Git at Google

 // 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"

 namespace v8 {
 namespace internal {

 enum {
   // The number of script generations tell how many GCs a script can
   // survive in the compilation cache, before it will be flushed if it
   // hasn't been used.
   NUMBER_OF_SCRIPT_GENERATIONS = 5,

   // The compilation cache consists of tables - one for each entry
   // kind plus extras for the script generations.
   NUMBER_OF_TABLE_ENTRIES =
       CompilationCache::LAST_ENTRY + NUMBER_OF_SCRIPT_GENERATIONS
 };


 // Current enable state of the compilation cache.
 static bool enabled = true;
 static inline bool IsEnabled() {
   return FLAG_compilation_cache && enabled;
 }

 // Keep separate tables for the different entry kinds.
 static Object* tables[NUMBER_OF_TABLE_ENTRIES] = { 0, };


 static Handle<CompilationCacheTable> AllocateTable(int size) {
   CALL_HEAP_FUNCTION(CompilationCacheTable::Allocate(size),
                      CompilationCacheTable);
 }


 static Handle<CompilationCacheTable> GetTable(int index) {
   ASSERT(index >= 0 && index < NUMBER_OF_TABLE_ENTRIES);
   Handle<CompilationCacheTable> result;
   if (tables[index]->IsUndefined()) {
     static const int kInitialCacheSize = 64;
     result = AllocateTable(kInitialCacheSize);
     tables[index] = *result;
   } else {
     CompilationCacheTable* table = CompilationCacheTable::cast(tables[index]);
     result = Handle<CompilationCacheTable>(table);
   }
   return result;
 }


 static Handle<JSFunction> Lookup(Handle<String> source,
                                  Handle<Context> context,
                                  CompilationCache::Entry entry) {
   // 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;
   { HandleScope scope;
     Handle<CompilationCacheTable> table = GetTable(entry);
     result = table->LookupEval(*source, *context);
   }
   if (result->IsJSFunction()) {
     return Handle<JSFunction>(JSFunction::cast(result));
   } else {
     return Handle<JSFunction>::null();
   }
 }


 static Handle<FixedArray> 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;
   { HandleScope scope;
     Handle<CompilationCacheTable> table = GetTable(CompilationCache::REGEXP);
     result = table->LookupRegExp(*source, flags);
   }
   if (result->IsFixedArray()) {
     return Handle<FixedArray>(FixedArray::cast(result));
   } else {
     return Handle<FixedArray>::null();
   }
 }


 // 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.
 static bool 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> CompilationCache::LookupScript(Handle<String> source,
                                                   Handle<Object> name,
                                                   int line_offset,
                                                   int column_offset) {
   if (!IsEnabled()) {
     return Handle<JSFunction>::null();
   }

   // Use an int for the generation index, so value range propagation
   // in gcc 4.3+ won't assume it can only go up to LAST_ENTRY when in
   // fact it can go up to SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS.
   int generation = SCRIPT;
   Object* result = NULL;

   // Probe the script generation tables. Make sure not to leak handles
   // into the caller's handle scope.
   { HandleScope scope;
     while (generation < SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS) {
       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;
         }
       }
       // Go to the next generation.
       generation++;
     }
   }

   static void* script_histogram = StatsTable::CreateHistogram(
       "V8.ScriptCache",
       0,
       NUMBER_OF_SCRIPT_GENERATIONS,
       NUMBER_OF_SCRIPT_GENERATIONS + 1);

   if (script_histogram != NULL) {
     // The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
     StatsTable::AddHistogramSample(script_histogram, generation - SCRIPT);
   }

   // 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 != SCRIPT) PutScript(source, boilerplate);
     Counters::compilation_cache_hits.Increment();
     return boilerplate;
   } else {
     Counters::compilation_cache_misses.Increment();
     return Handle<JSFunction>::null();
   }
 }


 Handle<JSFunction> CompilationCache::LookupEval(Handle<String> source,
                                                 Handle<Context> context,
                                                 Entry entry) {
   if (!IsEnabled()) {
     return Handle<JSFunction>::null();
   }

   ASSERT(entry == EVAL_GLOBAL || entry == EVAL_CONTEXTUAL);
   Handle<JSFunction> result = Lookup(source, context, entry);
   if (result.is_null()) {
     Counters::compilation_cache_misses.Increment();
   } else {
     Counters::compilation_cache_hits.Increment();
   }
   return result;
 }


 Handle<FixedArray> CompilationCache::LookupRegExp(Handle<String> source,
                                                   JSRegExp::Flags flags) {
   if (!IsEnabled()) {
     return Handle<FixedArray>::null();
   }

   Handle<FixedArray> result = Lookup(source, flags);
   if (result.is_null()) {
     Counters::compilation_cache_misses.Increment();
   } else {
     Counters::compilation_cache_hits.Increment();
   }
   return result;
 }


 void CompilationCache::PutScript(Handle<String> source,
                                  Handle<JSFunction> boilerplate) {
   if (!IsEnabled()) {
     return;
   }

   HandleScope scope;
   ASSERT(boilerplate->IsBoilerplate());
   Handle<CompilationCacheTable> table = GetTable(SCRIPT);
   CALL_HEAP_FUNCTION_VOID(table->Put(*source, *boilerplate));
 }


 void CompilationCache::PutEval(Handle<String> source,
                                Handle<Context> context,
                                Entry entry,
                                Handle<JSFunction> boilerplate) {
   if (!IsEnabled()) {
     return;
   }

   HandleScope scope;
   ASSERT(boilerplate->IsBoilerplate());
   Handle<CompilationCacheTable> table = GetTable(entry);
   CALL_HEAP_FUNCTION_VOID(table->PutEval(*source, *context, *boilerplate));
 }


 void CompilationCache::PutRegExp(Handle<String> source,
                                  JSRegExp::Flags flags,
                                  Handle<FixedArray> data) {
   if (!IsEnabled()) {
     return;
   }

   HandleScope scope;
   Handle<CompilationCacheTable> table = GetTable(REGEXP);
   CALL_HEAP_FUNCTION_VOID(table->PutRegExp(*source, flags, *data));
 }


 void CompilationCache::Clear() {
   for (int i = 0; i < NUMBER_OF_TABLE_ENTRIES; i++) {
     tables[i] = Heap::undefined_value();
   }
 }


 void CompilationCache::Iterate(ObjectVisitor* v) {
   v->VisitPointers(&tables[0], &tables[NUMBER_OF_TABLE_ENTRIES]);
 }


 void CompilationCache::MarkCompactPrologue() {
   ASSERT(LAST_ENTRY == SCRIPT);
   for (int i = NUMBER_OF_TABLE_ENTRIES - 1; i > SCRIPT; i--) {
     tables[i] = tables[i - 1];
   }
   for (int j = 0; j <= LAST_ENTRY; j++) {
     tables[j] = Heap::undefined_value();
   }
 }


 void CompilationCache::Enable() {
   enabled = true;
 }


 void CompilationCache::Disable() {
   enabled = false;
   Clear();
 }


 } }  // namespace v8::internal
	// 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"

	namespace v8 {
	namespace internal {

	enum {
	// The number of script generations tell how many GCs a script can
	// survive in the compilation cache, before it will be flushed if it
	// hasn't been used.
	NUMBER_OF_SCRIPT_GENERATIONS = 5,

	// The compilation cache consists of tables - one for each entry
	// kind plus extras for the script generations.
	NUMBER_OF_TABLE_ENTRIES =
	CompilationCache::LAST_ENTRY + NUMBER_OF_SCRIPT_GENERATIONS
	};


	// Current enable state of the compilation cache.
	static bool enabled = true;
	static inline bool IsEnabled() {
	return FLAG_compilation_cache && enabled;
	}

	// Keep separate tables for the different entry kinds.
	static Object* tables[NUMBER_OF_TABLE_ENTRIES] = { 0, };


	static Handle<CompilationCacheTable> AllocateTable(int size) {
	CALL_HEAP_FUNCTION(CompilationCacheTable::Allocate(size),
	CompilationCacheTable);
	}


	static Handle<CompilationCacheTable> GetTable(int index) {
	ASSERT(index >= 0 && index < NUMBER_OF_TABLE_ENTRIES);
	Handle<CompilationCacheTable> result;
	if (tables[index]->IsUndefined()) {
	static const int kInitialCacheSize = 64;
	result = AllocateTable(kInitialCacheSize);
	tables[index] = *result;
	} else {
	CompilationCacheTable* table = CompilationCacheTable::cast(tables[index]);
	result = Handle<CompilationCacheTable>(table);
	}
	return result;
	}


	static Handle<JSFunction> Lookup(Handle<String> source,
	Handle<Context> context,
	CompilationCache::Entry entry) {
	// 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;
	{ HandleScope scope;
	Handle<CompilationCacheTable> table = GetTable(entry);
	result = table->LookupEval(source, context);
	}
	if (result->IsJSFunction()) {
	return Handle<JSFunction>(JSFunction::cast(result));
	} else {
	return Handle<JSFunction>::null();
	}
	}


	static Handle<FixedArray> 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;
	{ HandleScope scope;
	Handle<CompilationCacheTable> table = GetTable(CompilationCache::REGEXP);
	result = table->LookupRegExp(*source, flags);
	}
	if (result->IsFixedArray()) {
	return Handle<FixedArray>(FixedArray::cast(result));
	} else {
	return Handle<FixedArray>::null();
	}
	}


	// 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.
	static bool 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> CompilationCache::LookupScript(Handle<String> source,
	Handle<Object> name,
	int line_offset,
	int column_offset) {
	if (!IsEnabled()) {
	return Handle<JSFunction>::null();
	}

	// Use an int for the generation index, so value range propagation
	// in gcc 4.3+ won't assume it can only go up to LAST_ENTRY when in
	// fact it can go up to SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS.
	int generation = SCRIPT;
	Object* result = NULL;

	// Probe the script generation tables. Make sure not to leak handles
	// into the caller's handle scope.
	{ HandleScope scope;
	while (generation < SCRIPT + NUMBER_OF_SCRIPT_GENERATIONS) {
	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;
	}
	}
	// Go to the next generation.
	generation++;
	}
	}

	static void* script_histogram = StatsTable::CreateHistogram(
	"V8.ScriptCache",
	0,
	NUMBER_OF_SCRIPT_GENERATIONS,
	NUMBER_OF_SCRIPT_GENERATIONS + 1);

	if (script_histogram != NULL) {
	// The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
	StatsTable::AddHistogramSample(script_histogram, generation - SCRIPT);
	}

	// 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 != SCRIPT) PutScript(source, boilerplate);
	Counters::compilation_cache_hits.Increment();
	return boilerplate;
	} else {
	Counters::compilation_cache_misses.Increment();
	return Handle<JSFunction>::null();
	}
	}


	Handle<JSFunction> CompilationCache::LookupEval(Handle<String> source,
	Handle<Context> context,
	Entry entry) {
	if (!IsEnabled()) {
	return Handle<JSFunction>::null();
	}

	ASSERT(entry == EVAL_GLOBAL \|\| entry == EVAL_CONTEXTUAL);
	Handle<JSFunction> result = Lookup(source, context, entry);
	if (result.is_null()) {
	Counters::compilation_cache_misses.Increment();
	} else {
	Counters::compilation_cache_hits.Increment();
	}
	return result;
	}


	Handle<FixedArray> CompilationCache::LookupRegExp(Handle<String> source,
	JSRegExp::Flags flags) {
	if (!IsEnabled()) {
	return Handle<FixedArray>::null();
	}

	Handle<FixedArray> result = Lookup(source, flags);
	if (result.is_null()) {
	Counters::compilation_cache_misses.Increment();
	} else {
	Counters::compilation_cache_hits.Increment();
	}
	return result;
	}


	void CompilationCache::PutScript(Handle<String> source,
	Handle<JSFunction> boilerplate) {
	if (!IsEnabled()) {
	return;
	}

	HandleScope scope;
	ASSERT(boilerplate->IsBoilerplate());
	Handle<CompilationCacheTable> table = GetTable(SCRIPT);
	CALL_HEAP_FUNCTION_VOID(table->Put(source, boilerplate));
	}


	void CompilationCache::PutEval(Handle<String> source,
	Handle<Context> context,
	Entry entry,
	Handle<JSFunction> boilerplate) {
	if (!IsEnabled()) {
	return;
	}

	HandleScope scope;
	ASSERT(boilerplate->IsBoilerplate());
	Handle<CompilationCacheTable> table = GetTable(entry);
	CALL_HEAP_FUNCTION_VOID(table->PutEval(source, context, *boilerplate));
	}



	void CompilationCache::PutRegExp(Handle<String> source,
	JSRegExp::Flags flags,
	Handle<FixedArray> data) {
	if (!IsEnabled()) {
	return;
	}

	HandleScope scope;
	Handle<CompilationCacheTable> table = GetTable(REGEXP);
	CALL_HEAP_FUNCTION_VOID(table->PutRegExp(source, flags, data));
	}


	void CompilationCache::Clear() {
	for (int i = 0; i < NUMBER_OF_TABLE_ENTRIES; i++) {
	tables[i] = Heap::undefined_value();
	}
	}


	void CompilationCache::Iterate(ObjectVisitor* v) {
	v->VisitPointers(&tables[0], &tables[NUMBER_OF_TABLE_ENTRIES]);
	}


	void CompilationCache::MarkCompactPrologue() {
	ASSERT(LAST_ENTRY == SCRIPT);
	for (int i = NUMBER_OF_TABLE_ENTRIES - 1; i > SCRIPT; i--) {
	tables[i] = tables[i - 1];
	}
	for (int j = 0; j <= LAST_ENTRY; j++) {
	tables[j] = Heap::undefined_value();
	}
	}


	void CompilationCache::Enable() {
	enabled = true;
	}


	void CompilationCache::Disable() {
	enabled = false;
	Clear();
	}


	} } // namespace v8::internal