js/src/vm/InvalidatingFuse.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef vm_InvalidatingFuse_h
   8 #define vm_InvalidatingFuse_h
   9
  10 #include "gc/Barrier.h"
  11 #include "gc/SweepingAPI.h"
  12 #include "vm/GuardFuse.h"
  13 class JSScript;
  14
  15 namespace js {
  16
  17 // [SMDOC] Invalidating Fuses
  18 //
  19 // An invalidating fuse will invalidate a set of dependent IonScripts when the
  20 // fuse is popped. In this way Ion can choose to ignore fuse guarded
  21 // possibilities when doing compilation.
  22 class InvalidatingFuse : public GuardFuse {
  23  public:
  24   // Register a script's IonScript as having a dependency on this fuse.
  25   virtual bool addFuseDependency(JSContext* cx, Handle<JSScript*> script) = 0;
  26 };
  27
  28 // [SMDOC] Invalidating Runtime Fuses
  29 //
  30 // A specialized sublass for handling runtime wide fuses. This provides a
  31 // version of addFuseDependency which records scripts into sets associated with
  32 // their home zone, and invalidates all sets across all zones linked to this
  33 // specific fuse.
  34 class InvalidatingRuntimeFuse : public InvalidatingFuse {
  35  public:
  36   virtual bool addFuseDependency(JSContext* cx,
  37                                  Handle<JSScript*> script) override;
  38   virtual void popFuse(JSContext* cx) override;
  39 };
  40
  41 // A (weak) set of scripts which are dependent on an associated fuse.
  42 //
  43 // Because it uses JS::WeakCache, GC tracing is taken care of without any need
  44 // for tracing in this class.
  45 class DependentScriptSet {
  46  public:
  47   DependentScriptSet(JSContext* cx, InvalidatingFuse* fuse);
  48
  49   InvalidatingFuse* associatedFuse;
  50   bool addScriptForFuse(InvalidatingFuse* fuse, Handle<JSScript*> script);
  51   void invalidateForFuse(JSContext* cx, InvalidatingFuse* fuse);
  52
  53  private:
  54   using WeakScriptSet = GCHashSet<WeakHeapPtr<JSScript*>,
  55                                   StableCellHasher<WeakHeapPtr<JSScript*>>,
  56                                   js::SystemAllocPolicy>;
  57   js::WeakCache<WeakScriptSet> weakScripts;
  58 };
  59
  60 class DependentScriptGroup {
  61   // A dependent script set pairs a fuse with a set of scripts which depend
  62   // on said fuse; this is a vector of script sets because the expectation for
  63   // now is that the number of runtime wide invalidating fuses will be small.
  64   // This will need to be revisited (convert to HashMap?) should that no
  65   // longer be the case
  66   //
  67   // Note: This isn't  traced through the zone, but rather through the use
  68   // of JS::WeakCache.
  69   Vector<DependentScriptSet, 1, SystemAllocPolicy> dependencies;
  70
  71  public:
  72   DependentScriptSet* getOrCreateDependentScriptSet(JSContext* cx,
  73                                                     InvalidatingFuse* fuse);
  74   DependentScriptSet* begin() { return dependencies.begin(); }
  75   DependentScriptSet* end() { return dependencies.end(); }
  76 };
  77
  78 }  // namespace js
  79
  80 #endif  // vm_InvalidatingFuse_h