js/src/jit/InterpreterEntryTrampoline.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 jit_InterpreterEntryTrampoline_h
   8 #define jit_InterpreterEntryTrampoline_h
   9
  10 #include "gc/Barrier.h"
  11 #include "gc/Tracer.h"
  12 #include "jit/JitCode.h"
  13 #include "js/AllocPolicy.h"
  14 #include "js/HashTable.h"
  15 #include "js/RootingAPI.h"
  16
  17 namespace js {
  18
  19 void ClearInterpreterEntryMap(JSRuntime* runtime);
  20
  21 namespace jit {
  22
  23 /*
  24  *  The EntryTrampolineMap is used to cache the trampoline code for
  25  *  each script as they are created.  These trampolines are created
  26  *  only under --emit-interpreter-entry and are used to identify which
  27  *  script is being interpeted when profiling with external profilers
  28  *  such as perf.
  29  *
  30  *  The map owns the JitCode objects that are created for each script,
  31  *  and keeps them alive at least as long as the script associated
  32  *  with it in case we need to re-enter the trampoline again.
  33  *
  34  *  As each script is finalized, the entry is manually removed from
  35  *  the table in BaseScript::finalize which will also release the
  36  *  trampoline code associated with it.
  37  *
  38  *  During a moving GC, the table is rekeyed in case any scripts
  39  *  have relocated.
  40  */
  41
  42 class EntryTrampoline {
  43   HeapPtr<JitCode*> entryTrampoline_;
  44
  45  public:
  46   void trace(JSTracer* trc) {
  47     TraceNullableEdge(trc, &entryTrampoline_, "interpreter-entry-trampoline");
  48   }
  49
  50   explicit EntryTrampoline(JSContext* cx, JitCode* code) {
  51     MOZ_ASSERT(code);
  52     entryTrampoline_ = code;
  53   }
  54
  55   uint8_t* raw() {
  56     MOZ_ASSERT(entryTrampoline_, "Empty trampoline code.");
  57     return entryTrampoline_->raw();
  58   }
  59
  60 #ifdef JSGC_HASH_TABLE_CHECKS
  61   void checkTrampolineAfterMovingGC();
  62 #endif
  63 };
  64
  65 using JSScriptToTrampolineMap =
  66     HashMap<HeapPtr<BaseScript*>, EntryTrampoline,
  67             DefaultHasher<HeapPtr<BaseScript*>>, SystemAllocPolicy>;
  68 class EntryTrampolineMap : public JSScriptToTrampolineMap {
  69  public:
  70   void traceTrampolineCode(JSTracer* trc);
  71   void updateScriptsAfterMovingGC(void);
  72 #ifdef JSGC_HASH_TABLE_CHECKS
  73   void checkScriptsAfterMovingGC();
  74 #endif
  75 };
  76
  77 }  // namespace jit
  78 }  // namespace js
  79 #endif /* jit_InterpreterEntryTrampoline_h */