1 // Copyright 2012 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 #ifndef V8_COMPILATION_CACHE_H_
6 #define V8_COMPILATION_CACHE_H_
7 
8 namespace v8 {
9 namespace internal {
10 
11 // The compilation cache consists of several generational sub-caches which uses
12 // this class as a base class. A sub-cache contains a compilation cache tables
13 // for each generation of the sub-cache. Since the same source code string has
14 // different compiled code for scripts and evals, we use separate sub-caches
15 // for different compilation modes, to avoid retrieving the wrong result.
16 class CompilationSubCache {
17  public:
CompilationSubCache(Isolate * isolate,int generations)18   CompilationSubCache(Isolate* isolate, int generations)
19       : isolate_(isolate),
20         generations_(generations) {
21     tables_ = NewArray<Object*>(generations);
22   }
23 
~CompilationSubCache()24   ~CompilationSubCache() { DeleteArray(tables_); }
25 
26   // Index for the first generation in the cache.
27   static const int kFirstGeneration = 0;
28 
29   // Get the compilation cache tables for a specific generation.
30   Handle<CompilationCacheTable> GetTable(int generation);
31 
32   // Accessors for first generation.
GetFirstTable()33   Handle<CompilationCacheTable> GetFirstTable() {
34     return GetTable(kFirstGeneration);
35   }
SetFirstTable(Handle<CompilationCacheTable> value)36   void SetFirstTable(Handle<CompilationCacheTable> value) {
37     DCHECK(kFirstGeneration < generations_);
38     tables_[kFirstGeneration] = *value;
39   }
40 
41   // Age the sub-cache by evicting the oldest generation and creating a new
42   // young generation.
43   void Age();
44 
45   // GC support.
46   void Iterate(ObjectVisitor* v);
47   void IterateFunctions(ObjectVisitor* v);
48 
49   // Clear this sub-cache evicting all its content.
50   void Clear();
51 
52   // Remove given shared function info from sub-cache.
53   void Remove(Handle<SharedFunctionInfo> function_info);
54 
55   // Number of generations in this sub-cache.
generations()56   inline int generations() { return generations_; }
57 
58  protected:
isolate()59   Isolate* isolate() { return isolate_; }
60 
61  private:
62   Isolate* isolate_;
63   int generations_;  // Number of generations.
64   Object** tables_;  // Compilation cache tables - one for each generation.
65 
66   DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationSubCache);
67 };
68 
69 
70 // Sub-cache for scripts.
71 class CompilationCacheScript : public CompilationSubCache {
72  public:
73   CompilationCacheScript(Isolate* isolate, int generations);
74 
75   Handle<SharedFunctionInfo> Lookup(Handle<String> source,
76                                     Handle<Object> name,
77                                     int line_offset,
78                                     int column_offset,
79                                     bool is_shared_cross_origin,
80                                     Handle<Context> context);
81   void Put(Handle<String> source,
82            Handle<Context> context,
83            Handle<SharedFunctionInfo> function_info);
84 
85  private:
86   bool HasOrigin(Handle<SharedFunctionInfo> function_info,
87                  Handle<Object> name,
88                  int line_offset,
89                  int column_offset,
90                  bool is_shared_cross_origin);
91 
92   void* script_histogram_;
93   bool script_histogram_initialized_;
94 
95   DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheScript);
96 };
97 
98 
99 // Sub-cache for eval scripts. Two caches for eval are used. One for eval calls
100 // in native contexts and one for eval calls in other contexts. The cache
101 // considers the following pieces of information when checking for matching
102 // entries:
103 // 1. The source string.
104 // 2. The shared function info of the calling function.
105 // 3. Whether the source should be compiled as strict code or as sloppy code.
106 //    Note: Currently there are clients of CompileEval that always compile
107 //    sloppy code even if the calling function is a strict mode function.
108 //    More specifically these are the CompileString, DebugEvaluate and
109 //    DebugEvaluateGlobal runtime functions.
110 // 4. The start position of the calling scope.
111 class CompilationCacheEval: public CompilationSubCache {
112  public:
CompilationCacheEval(Isolate * isolate,int generations)113   CompilationCacheEval(Isolate* isolate, int generations)
114       : CompilationSubCache(isolate, generations) { }
115 
116   MaybeHandle<SharedFunctionInfo> Lookup(Handle<String> source,
117                                          Handle<SharedFunctionInfo> outer_info,
118                                          StrictMode strict_mode,
119                                          int scope_position);
120 
121   void Put(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
122            Handle<SharedFunctionInfo> function_info, int scope_position);
123 
124  private:
125   DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheEval);
126 };
127 
128 
129 // Sub-cache for regular expressions.
130 class CompilationCacheRegExp: public CompilationSubCache {
131  public:
CompilationCacheRegExp(Isolate * isolate,int generations)132   CompilationCacheRegExp(Isolate* isolate, int generations)
133       : CompilationSubCache(isolate, generations) { }
134 
135   MaybeHandle<FixedArray> Lookup(Handle<String> source, JSRegExp::Flags flags);
136 
137   void Put(Handle<String> source,
138            JSRegExp::Flags flags,
139            Handle<FixedArray> data);
140  private:
141   DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheRegExp);
142 };
143 
144 
145 // The compilation cache keeps shared function infos for compiled
146 // scripts and evals. The shared function infos are looked up using
147 // the source string as the key. For regular expressions the
148 // compilation data is cached.
149 class CompilationCache {
150  public:
151   // Finds the script shared function info for a source
152   // string. Returns an empty handle if the cache doesn't contain a
153   // script for the given source string with the right origin.
154   MaybeHandle<SharedFunctionInfo> LookupScript(
155       Handle<String> source, Handle<Object> name, int line_offset,
156       int column_offset, bool is_shared_cross_origin, Handle<Context> context);
157 
158   // Finds the shared function info for a source string for eval in a
159   // given context.  Returns an empty handle if the cache doesn't
160   // contain a script for the given source string.
161   MaybeHandle<SharedFunctionInfo> LookupEval(
162       Handle<String> source, Handle<SharedFunctionInfo> outer_info,
163       Handle<Context> context, StrictMode strict_mode, int scope_position);
164 
165   // Returns the regexp data associated with the given regexp if it
166   // is in cache, otherwise an empty handle.
167   MaybeHandle<FixedArray> LookupRegExp(
168       Handle<String> source, JSRegExp::Flags flags);
169 
170   // Associate the (source, kind) pair to the shared function
171   // info. This may overwrite an existing mapping.
172   void PutScript(Handle<String> source,
173                  Handle<Context> context,
174                  Handle<SharedFunctionInfo> function_info);
175 
176   // Associate the (source, context->closure()->shared(), kind) triple
177   // with the shared function info. This may overwrite an existing mapping.
178   void PutEval(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
179                Handle<Context> context,
180                Handle<SharedFunctionInfo> function_info, int scope_position);
181 
182   // Associate the (source, flags) pair to the given regexp data.
183   // This may overwrite an existing mapping.
184   void PutRegExp(Handle<String> source,
185                  JSRegExp::Flags flags,
186                  Handle<FixedArray> data);
187 
188   // Clear the cache - also used to initialize the cache at startup.
189   void Clear();
190 
191   // Remove given shared function info from all caches.
192   void Remove(Handle<SharedFunctionInfo> function_info);
193 
194   // GC support.
195   void Iterate(ObjectVisitor* v);
196   void IterateFunctions(ObjectVisitor* v);
197 
198   // Notify the cache that a mark-sweep garbage collection is about to
199   // take place. This is used to retire entries from the cache to
200   // avoid keeping them alive too long without using them.
201   void MarkCompactPrologue();
202 
203   // Enable/disable compilation cache. Used by debugger to disable compilation
204   // cache during debugging to make sure new scripts are always compiled.
205   void Enable();
206   void Disable();
207 
208  private:
209   explicit CompilationCache(Isolate* isolate);
210   ~CompilationCache();
211 
212   HashMap* EagerOptimizingSet();
213 
214   // The number of sub caches covering the different types to cache.
215   static const int kSubCacheCount = 4;
216 
IsEnabled()217   bool IsEnabled() { return FLAG_compilation_cache && enabled_; }
218 
isolate()219   Isolate* isolate() { return isolate_; }
220 
221   Isolate* isolate_;
222 
223   CompilationCacheScript script_;
224   CompilationCacheEval eval_global_;
225   CompilationCacheEval eval_contextual_;
226   CompilationCacheRegExp reg_exp_;
227   CompilationSubCache* subcaches_[kSubCacheCount];
228 
229   // Current enable state of the compilation cache.
230   bool enabled_;
231 
232   friend class Isolate;
233 
234   DISALLOW_COPY_AND_ASSIGN(CompilationCache);
235 };
236 
237 
238 } }  // namespace v8::internal
239 
240 #endif  // V8_COMPILATION_CACHE_H_
241