text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef V8_CODEGEN_COMPILATION_CACHE_H_
  #define V8_CODEGEN_COMPILATION_CACHE_H_
  
  #include "src/objects/compilation-cache.h"
  #include "src/utils/allocation.h"
  
  namespace v8 {
  namespace internal {
  
  template <typename T>
  class Handle;
  
  class RootVisitor;
  
  // The compilation cache consists of several generational sub-caches which uses
  // this class as a base class. A sub-cache contains a compilation cache tables
  // for each generation of the sub-cache. Since the same source code string has
  // different compiled code for scripts and evals, we use separate sub-caches
  // for different compilation modes, to avoid retrieving the wrong result.
  class CompilationSubCache {
   public:
    CompilationSubCache(Isolate* isolate, int generations)
        : isolate_(isolate), generations_(generations) {
      tables_ = NewArray<Object>(generations);
    }
  
    ~CompilationSubCache() { DeleteArray(tables_); }
  
    // Index for the first generation in the cache.
    static const int kFirstGeneration = 0;
  
    // Get the compilation cache tables for a specific generation.
    Handle<CompilationCacheTable> GetTable(int generation);
  
    // Accessors for first generation.
    Handle<CompilationCacheTable> GetFirstTable() {
      return GetTable(kFirstGeneration);
    }
    void SetFirstTable(Handle<CompilationCacheTable> value) {
      DCHECK_LT(kFirstGeneration, generations_);
      tables_[kFirstGeneration] = *value;
    }
  
    // Age the sub-cache by evicting the oldest generation and creating a new
    // young generation.
    void Age();
  
    // GC support.
    void Iterate(RootVisitor* v);
  
    // Clear this sub-cache evicting all its content.
    void Clear();
  
    // Remove given shared function info from sub-cache.
    void Remove(Handle<SharedFunctionInfo> function_info);
  
    // Number of generations in this sub-cache.
    inline int generations() { return generations_; }
  
   protected:
    Isolate* isolate() { return isolate_; }
  
   private:
    Isolate* isolate_;
    int generations_;  // Number of generations.
    Object* tables_;   // Compilation cache tables - one for each generation.
  
    DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationSubCache);
  };
  
  // Sub-cache for scripts.
  class CompilationCacheScript : public CompilationSubCache {
   public:
    explicit CompilationCacheScript(Isolate* isolate);
  
    MaybeHandle<SharedFunctionInfo> Lookup(Handle<String> source,
                                           MaybeHandle<Object> name,
                                           int line_offset, int column_offset,
                                           ScriptOriginOptions resource_options,
                                           Handle<Context> native_context,
                                           LanguageMode language_mode);
  
    void Put(Handle<String> source, Handle<Context> context,
             LanguageMode language_mode,
             Handle<SharedFunctionInfo> function_info);
  
   private:
    bool HasOrigin(Handle<SharedFunctionInfo> function_info,
                   MaybeHandle<Object> name, int line_offset, int column_offset,
                   ScriptOriginOptions resource_options);
  
    DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheScript);
  };
  
  // Sub-cache for eval scripts. Two caches for eval are used. One for eval calls
  // in native contexts and one for eval calls in other contexts. The cache
  // considers the following pieces of information when checking for matching
  // entries:
  // 1. The source string.
  // 2. The shared function info of the calling function.
  // 3. Whether the source should be compiled as strict code or as sloppy code.
  //    Note: Currently there are clients of CompileEval that always compile
  //    sloppy code even if the calling function is a strict mode function.
  //    More specifically these are the CompileString, DebugEvaluate and
  //    DebugEvaluateGlobal runtime functions.
  // 4. The start position of the calling scope.
  class CompilationCacheEval : public CompilationSubCache {
   public:
    explicit CompilationCacheEval(Isolate* isolate)
        : CompilationSubCache(isolate, 1) {}
  
    InfoCellPair Lookup(Handle<String> source,
                        Handle<SharedFunctionInfo> outer_info,
                        Handle<Context> native_context,
                        LanguageMode language_mode, int position);
  
    void Put(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
             Handle<SharedFunctionInfo> function_info,
             Handle<Context> native_context, Handle<FeedbackCell> feedback_cell,
             int position);
  
   private:
    DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheEval);
  };
  
  // Sub-cache for regular expressions.
  class CompilationCacheRegExp : public CompilationSubCache {
   public:
    CompilationCacheRegExp(Isolate* isolate, int generations)
        : CompilationSubCache(isolate, generations) {}
  
    MaybeHandle<FixedArray> Lookup(Handle<String> source, JSRegExp::Flags flags);
  
    void Put(Handle<String> source, JSRegExp::Flags flags,
             Handle<FixedArray> data);
  
   private:
    DISALLOW_IMPLICIT_CONSTRUCTORS(CompilationCacheRegExp);
  };
  
  // The compilation cache keeps shared function infos for compiled
  // scripts and evals. The shared function infos are looked up using
  // the source string as the key. For regular expressions the
  // compilation data is cached.
  class V8_EXPORT_PRIVATE CompilationCache {
   public:
    // Finds the script shared function info for a source
    // string. Returns an empty handle if the cache doesn't contain a
    // script for the given source string with the right origin.
    MaybeHandle<SharedFunctionInfo> LookupScript(
        Handle<String> source, MaybeHandle<Object> name, int line_offset,
        int column_offset, ScriptOriginOptions resource_options,
        Handle<Context> native_context, LanguageMode language_mode);
  
    // Finds the shared function info for a source string for eval in a
    // given context.  Returns an empty handle if the cache doesn't
    // contain a script for the given source string.
    InfoCellPair LookupEval(Handle<String> source,
                            Handle<SharedFunctionInfo> outer_info,
                            Handle<Context> context, LanguageMode language_mode,
                            int position);
  
    // Returns the regexp data associated with the given regexp if it
    // is in cache, otherwise an empty handle.
    MaybeHandle<FixedArray> LookupRegExp(Handle<String> source,
                                         JSRegExp::Flags flags);
  
    // Associate the (source, kind) pair to the shared function
    // info. This may overwrite an existing mapping.
    void PutScript(Handle<String> source, Handle<Context> native_context,
                   LanguageMode language_mode,
                   Handle<SharedFunctionInfo> function_info);
  
    // Associate the (source, context->closure()->shared(), kind) triple
    // with the shared function info. This may overwrite an existing mapping.
    void PutEval(Handle<String> source, Handle<SharedFunctionInfo> outer_info,
                 Handle<Context> context,
                 Handle<SharedFunctionInfo> function_info,
                 Handle<FeedbackCell> feedback_cell, int position);
  
    // Associate the (source, flags) pair to the given regexp data.
    // This may overwrite an existing mapping.
    void PutRegExp(Handle<String> source, JSRegExp::Flags flags,
                   Handle<FixedArray> data);
  
    // Clear the cache - also used to initialize the cache at startup.
    void Clear();
  
    // Remove given shared function info from all caches.
    void Remove(Handle<SharedFunctionInfo> function_info);
  
    // GC support.
    void Iterate(RootVisitor* v);
  
    // Notify the cache that a mark-sweep garbage collection is about to
    // take place. This is used to retire entries from the cache to
    // avoid keeping them alive too long without using them.
    void MarkCompactPrologue();
  
    // Enable/disable compilation cache. Used by debugger to disable compilation
    // cache during debugging to make sure new scripts are always compiled.
    void Enable();
    void Disable();
  
   private:
    explicit CompilationCache(Isolate* isolate);
    ~CompilationCache() = default;
  
    base::HashMap* EagerOptimizingSet();
  
    // The number of sub caches covering the different types to cache.
    static const int kSubCacheCount = 4;
  
    bool IsEnabled() const { return FLAG_compilation_cache && enabled_; }
  
    Isolate* isolate() const { return isolate_; }
  
    Isolate* isolate_;
  
    CompilationCacheScript script_;
    CompilationCacheEval eval_global_;
    CompilationCacheEval eval_contextual_;
    CompilationCacheRegExp reg_exp_;
    CompilationSubCache* subcaches_[kSubCacheCount];
  
    // Current enable state of the compilation cache.
    bool enabled_;
  
    friend class Isolate;
  
    DISALLOW_COPY_AND_ASSIGN(CompilationCache);
  };
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_CODEGEN_COMPILATION_CACHE_H_
  