1// Copyright 2011 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/v8.h"
6
7#include "src/assembler.h"
8#include "src/compilation-cache.h"
9#include "src/serialize.h"
10
11namespace v8 {
12namespace internal {
13
14
15// The number of generations for each sub cache.
16// The number of ScriptGenerations is carefully chosen based on histograms.
17// See issue 458: http://code.google.com/p/v8/issues/detail?id=458
18static const int kScriptGenerations = 5;
19static const int kEvalGlobalGenerations = 2;
20static const int kEvalContextualGenerations = 2;
21static const int kRegExpGenerations = 2;
22
23// Initial size of each compilation cache table allocated.
24static const int kInitialCacheSize = 64;
25
26
27CompilationCache::CompilationCache(Isolate* isolate)
28    : isolate_(isolate),
29      script_(isolate, kScriptGenerations),
30      eval_global_(isolate, kEvalGlobalGenerations),
31      eval_contextual_(isolate, kEvalContextualGenerations),
32      reg_exp_(isolate, kRegExpGenerations),
33      enabled_(true) {
34  CompilationSubCache* subcaches[kSubCacheCount] =
35    {&script_, &eval_global_, &eval_contextual_, &reg_exp_};
36  for (int i = 0; i < kSubCacheCount; ++i) {
37    subcaches_[i] = subcaches[i];
38  }
39}
40
41
42CompilationCache::~CompilationCache() {}
43
44
45Handle<CompilationCacheTable> CompilationSubCache::GetTable(int generation) {
46  DCHECK(generation < generations_);
47  Handle<CompilationCacheTable> result;
48  if (tables_[generation]->IsUndefined()) {
49    result = CompilationCacheTable::New(isolate(), kInitialCacheSize);
50    tables_[generation] = *result;
51  } else {
52    CompilationCacheTable* table =
53        CompilationCacheTable::cast(tables_[generation]);
54    result = Handle<CompilationCacheTable>(table, isolate());
55  }
56  return result;
57}
58
59
60void CompilationSubCache::Age() {
61  // Age the generations implicitly killing off the oldest.
62  for (int i = generations_ - 1; i > 0; i--) {
63    tables_[i] = tables_[i - 1];
64  }
65
66  // Set the first generation as unborn.
67  tables_[0] = isolate()->heap()->undefined_value();
68}
69
70
71void CompilationSubCache::IterateFunctions(ObjectVisitor* v) {
72  Object* undefined = isolate()->heap()->undefined_value();
73  for (int i = 0; i < generations_; i++) {
74    if (tables_[i] != undefined) {
75      reinterpret_cast<CompilationCacheTable*>(tables_[i])->IterateElements(v);
76    }
77  }
78}
79
80
81void CompilationSubCache::Iterate(ObjectVisitor* v) {
82  v->VisitPointers(&tables_[0], &tables_[generations_]);
83}
84
85
86void CompilationSubCache::Clear() {
87  MemsetPointer(tables_, isolate()->heap()->undefined_value(), generations_);
88}
89
90
91void CompilationSubCache::Remove(Handle<SharedFunctionInfo> function_info) {
92  // Probe the script generation tables. Make sure not to leak handles
93  // into the caller's handle scope.
94  { HandleScope scope(isolate());
95    for (int generation = 0; generation < generations(); generation++) {
96      Handle<CompilationCacheTable> table = GetTable(generation);
97      table->Remove(*function_info);
98    }
99  }
100}
101
102
103CompilationCacheScript::CompilationCacheScript(Isolate* isolate,
104                                               int generations)
105    : CompilationSubCache(isolate, generations),
106      script_histogram_(NULL),
107      script_histogram_initialized_(false) { }
108
109
110// We only re-use a cached function for some script source code if the
111// script originates from the same place. This is to avoid issues
112// when reporting errors, etc.
113bool CompilationCacheScript::HasOrigin(
114    Handle<SharedFunctionInfo> function_info,
115    Handle<Object> name,
116    int line_offset,
117    int column_offset,
118    bool is_shared_cross_origin) {
119  Handle<Script> script =
120      Handle<Script>(Script::cast(function_info->script()), isolate());
121  // If the script name isn't set, the boilerplate script should have
122  // an undefined name to have the same origin.
123  if (name.is_null()) {
124    return script->name()->IsUndefined();
125  }
126  // Do the fast bailout checks first.
127  if (line_offset != script->line_offset()->value()) return false;
128  if (column_offset != script->column_offset()->value()) return false;
129  // Check that both names are strings. If not, no match.
130  if (!name->IsString() || !script->name()->IsString()) return false;
131  // Were both scripts tagged by the embedder as being shared cross-origin?
132  if (is_shared_cross_origin != script->is_shared_cross_origin()) return false;
133  // Compare the two name strings for equality.
134  return String::Equals(Handle<String>::cast(name),
135                        Handle<String>(String::cast(script->name())));
136}
137
138
139// TODO(245): Need to allow identical code from different contexts to
140// be cached in the same script generation. Currently the first use
141// will be cached, but subsequent code from different source / line
142// won't.
143Handle<SharedFunctionInfo> CompilationCacheScript::Lookup(
144    Handle<String> source,
145    Handle<Object> name,
146    int line_offset,
147    int column_offset,
148    bool is_shared_cross_origin,
149    Handle<Context> context) {
150  Object* result = NULL;
151  int generation;
152
153  // Probe the script generation tables. Make sure not to leak handles
154  // into the caller's handle scope.
155  { HandleScope scope(isolate());
156    for (generation = 0; generation < generations(); generation++) {
157      Handle<CompilationCacheTable> table = GetTable(generation);
158      Handle<Object> probe = table->Lookup(source, context);
159      if (probe->IsSharedFunctionInfo()) {
160        Handle<SharedFunctionInfo> function_info =
161            Handle<SharedFunctionInfo>::cast(probe);
162        // Break when we've found a suitable shared function info that
163        // matches the origin.
164        if (HasOrigin(function_info,
165                      name,
166                      line_offset,
167                      column_offset,
168                      is_shared_cross_origin)) {
169          result = *function_info;
170          break;
171        }
172      }
173    }
174  }
175
176  if (!script_histogram_initialized_) {
177    script_histogram_ = isolate()->stats_table()->CreateHistogram(
178        "V8.ScriptCache",
179        0,
180        kScriptGenerations,
181        kScriptGenerations + 1);
182    script_histogram_initialized_ = true;
183  }
184
185  if (script_histogram_ != NULL) {
186    // The level NUMBER_OF_SCRIPT_GENERATIONS is equivalent to a cache miss.
187    isolate()->stats_table()->AddHistogramSample(script_histogram_, generation);
188  }
189
190  // Once outside the manacles of the handle scope, we need to recheck
191  // to see if we actually found a cached script. If so, we return a
192  // handle created in the caller's handle scope.
193  if (result != NULL) {
194    Handle<SharedFunctionInfo> shared(SharedFunctionInfo::cast(result),
195                                      isolate());
196    DCHECK(HasOrigin(shared,
197                     name,
198                     line_offset,
199                     column_offset,
200                     is_shared_cross_origin));
201    // If the script was found in a later generation, we promote it to
202    // the first generation to let it survive longer in the cache.
203    if (generation != 0) Put(source, context, shared);
204    isolate()->counters()->compilation_cache_hits()->Increment();
205    return shared;
206  } else {
207    isolate()->counters()->compilation_cache_misses()->Increment();
208    return Handle<SharedFunctionInfo>::null();
209  }
210}
211
212
213void CompilationCacheScript::Put(Handle<String> source,
214                                 Handle<Context> context,
215                                 Handle<SharedFunctionInfo> function_info) {
216  HandleScope scope(isolate());
217  Handle<CompilationCacheTable> table = GetFirstTable();
218  SetFirstTable(
219      CompilationCacheTable::Put(table, source, context, function_info));
220}
221
222
223MaybeHandle<SharedFunctionInfo> CompilationCacheEval::Lookup(
224    Handle<String> source, Handle<SharedFunctionInfo> outer_info,
225    StrictMode strict_mode, int scope_position) {
226  HandleScope scope(isolate());
227  // Make sure not to leak the table into the surrounding handle
228  // scope. Otherwise, we risk keeping old tables around even after
229  // having cleared the cache.
230  Handle<Object> result = isolate()->factory()->undefined_value();
231  int generation;
232  for (generation = 0; generation < generations(); generation++) {
233    Handle<CompilationCacheTable> table = GetTable(generation);
234    result = table->LookupEval(source, outer_info, strict_mode, scope_position);
235    if (result->IsSharedFunctionInfo()) break;
236  }
237  if (result->IsSharedFunctionInfo()) {
238    Handle<SharedFunctionInfo> function_info =
239        Handle<SharedFunctionInfo>::cast(result);
240    if (generation != 0) {
241      Put(source, outer_info, function_info, scope_position);
242    }
243    isolate()->counters()->compilation_cache_hits()->Increment();
244    return scope.CloseAndEscape(function_info);
245  } else {
246    isolate()->counters()->compilation_cache_misses()->Increment();
247    return MaybeHandle<SharedFunctionInfo>();
248  }
249}
250
251
252void CompilationCacheEval::Put(Handle<String> source,
253                               Handle<SharedFunctionInfo> outer_info,
254                               Handle<SharedFunctionInfo> function_info,
255                               int scope_position) {
256  HandleScope scope(isolate());
257  Handle<CompilationCacheTable> table = GetFirstTable();
258  table = CompilationCacheTable::PutEval(table, source, outer_info,
259                                         function_info, scope_position);
260  SetFirstTable(table);
261}
262
263
264MaybeHandle<FixedArray> CompilationCacheRegExp::Lookup(
265    Handle<String> source,
266    JSRegExp::Flags flags) {
267  HandleScope scope(isolate());
268  // Make sure not to leak the table into the surrounding handle
269  // scope. Otherwise, we risk keeping old tables around even after
270  // having cleared the cache.
271  Handle<Object> result = isolate()->factory()->undefined_value();
272  int generation;
273  for (generation = 0; generation < generations(); generation++) {
274    Handle<CompilationCacheTable> table = GetTable(generation);
275    result = table->LookupRegExp(source, flags);
276    if (result->IsFixedArray()) break;
277  }
278  if (result->IsFixedArray()) {
279    Handle<FixedArray> data = Handle<FixedArray>::cast(result);
280    if (generation != 0) {
281      Put(source, flags, data);
282    }
283    isolate()->counters()->compilation_cache_hits()->Increment();
284    return scope.CloseAndEscape(data);
285  } else {
286    isolate()->counters()->compilation_cache_misses()->Increment();
287    return MaybeHandle<FixedArray>();
288  }
289}
290
291
292void CompilationCacheRegExp::Put(Handle<String> source,
293                                 JSRegExp::Flags flags,
294                                 Handle<FixedArray> data) {
295  HandleScope scope(isolate());
296  Handle<CompilationCacheTable> table = GetFirstTable();
297  SetFirstTable(CompilationCacheTable::PutRegExp(table, source, flags, data));
298}
299
300
301void CompilationCache::Remove(Handle<SharedFunctionInfo> function_info) {
302  if (!IsEnabled()) return;
303
304  eval_global_.Remove(function_info);
305  eval_contextual_.Remove(function_info);
306  script_.Remove(function_info);
307}
308
309
310MaybeHandle<SharedFunctionInfo> CompilationCache::LookupScript(
311    Handle<String> source,
312    Handle<Object> name,
313    int line_offset,
314    int column_offset,
315    bool is_shared_cross_origin,
316    Handle<Context> context) {
317  if (!IsEnabled()) return MaybeHandle<SharedFunctionInfo>();
318
319  return script_.Lookup(source, name, line_offset, column_offset,
320                        is_shared_cross_origin, context);
321}
322
323
324MaybeHandle<SharedFunctionInfo> CompilationCache::LookupEval(
325    Handle<String> source, Handle<SharedFunctionInfo> outer_info,
326    Handle<Context> context, StrictMode strict_mode, int scope_position) {
327  if (!IsEnabled()) return MaybeHandle<SharedFunctionInfo>();
328
329  MaybeHandle<SharedFunctionInfo> result;
330  if (context->IsNativeContext()) {
331    result =
332        eval_global_.Lookup(source, outer_info, strict_mode, scope_position);
333  } else {
334    DCHECK(scope_position != RelocInfo::kNoPosition);
335    result = eval_contextual_.Lookup(source, outer_info, strict_mode,
336                                     scope_position);
337  }
338  return result;
339}
340
341
342MaybeHandle<FixedArray> CompilationCache::LookupRegExp(Handle<String> source,
343                                                       JSRegExp::Flags flags) {
344  if (!IsEnabled()) return MaybeHandle<FixedArray>();
345
346  return reg_exp_.Lookup(source, flags);
347}
348
349
350void CompilationCache::PutScript(Handle<String> source,
351                                 Handle<Context> context,
352                                 Handle<SharedFunctionInfo> function_info) {
353  if (!IsEnabled()) return;
354
355  script_.Put(source, context, function_info);
356}
357
358
359void CompilationCache::PutEval(Handle<String> source,
360                               Handle<SharedFunctionInfo> outer_info,
361                               Handle<Context> context,
362                               Handle<SharedFunctionInfo> function_info,
363                               int scope_position) {
364  if (!IsEnabled()) return;
365
366  HandleScope scope(isolate());
367  if (context->IsNativeContext()) {
368    eval_global_.Put(source, outer_info, function_info, scope_position);
369  } else {
370    DCHECK(scope_position != RelocInfo::kNoPosition);
371    eval_contextual_.Put(source, outer_info, function_info, scope_position);
372  }
373}
374
375
376
377void CompilationCache::PutRegExp(Handle<String> source,
378                                 JSRegExp::Flags flags,
379                                 Handle<FixedArray> data) {
380  if (!IsEnabled()) {
381    return;
382  }
383
384  reg_exp_.Put(source, flags, data);
385}
386
387
388void CompilationCache::Clear() {
389  for (int i = 0; i < kSubCacheCount; i++) {
390    subcaches_[i]->Clear();
391  }
392}
393
394
395void CompilationCache::Iterate(ObjectVisitor* v) {
396  for (int i = 0; i < kSubCacheCount; i++) {
397    subcaches_[i]->Iterate(v);
398  }
399}
400
401
402void CompilationCache::IterateFunctions(ObjectVisitor* v) {
403  for (int i = 0; i < kSubCacheCount; i++) {
404    subcaches_[i]->IterateFunctions(v);
405  }
406}
407
408
409void CompilationCache::MarkCompactPrologue() {
410  for (int i = 0; i < kSubCacheCount; i++) {
411    subcaches_[i]->Age();
412  }
413}
414
415
416void CompilationCache::Enable() {
417  enabled_ = true;
418}
419
420
421void CompilationCache::Disable() {
422  enabled_ = false;
423  Clear();
424}
425
426
427} }  // namespace v8::internal
428