text: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   * vim: set ts=4 sw=4 et tw=99:
   *
   * ***** BEGIN LICENSE BLOCK *****
   * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   *
   * The contents of this file are subject to the Mozilla Public License Version
   * 1.1 (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   * http://www.mozilla.org/MPL/
   *
   * Software distributed under the License is distributed on an "AS IS" basis,
   * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
   * for the specific language governing rights and limitations under the
   * License.
   *
   * The Original Code is Mozilla SpiderMonkey JavaScript 1.9 code, released
   * May 28, 2008.
   *
   * The Initial Developer of the Original Code is
   *   Brendan Eich <brendan@mozilla.org>
   *
   * Contributor(s):
   *   David Anderson <danderson@mozilla.com>
   *
   * Alternatively, the contents of this file may be used under the terms of
   * either of the GNU General Public License Version 2 or later (the "GPL"),
   * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
   * in which case the provisions of the GPL or the LGPL are applicable instead
   * of those above. If you wish to allow use of your version of this file only
   * under the terms of either the GPL or the LGPL, and not to allow others to
   * use your version of this file under the terms of the MPL, indicate your
   * decision by deleting the provisions above and replace them with the notice
   * and other provisions required by the GPL or the LGPL. If you do not delete
   * the provisions above, a recipient may use your version of this file under
   * the terms of any one of the MPL, the GPL or the LGPL.
   *
   * ***** END LICENSE BLOCK ***** */
  
  #if !defined jsjaeger_imm_sync_h__ && defined JS_METHODJIT && defined JS_NUNBOX32
  #define jsjaeger_imm_sync_h__
  
  #include "methodjit/MachineRegs.h"
  #include "methodjit/FrameEntry.h"
  #include "CodeGenIncludes.h"
  
  namespace js {
  namespace mjit {
  
  class FrameState;
  
  /*
   * This is a structure nestled within the FrameState used for safely syncing
   * registers to memory during transitions from the fast path into a slow path
   * stub call. During this process, the frame itself is immutable, and we may
   * run out of registers needed to remat copies.
   *
   * This structure maintains a mapping of the tracker used to perform ad-hoc
   * register allocation.
   */
  class ImmutableSync
  {
      typedef JSC::MacroAssembler::RegisterID RegisterID;
      typedef JSC::MacroAssembler::Address Address;
  
      struct SyncEntry {
          /*
           * NB: clobbered and sync mean the same thing: the register associated
           * in the FrameEntry is no longer valid, and has been written back.
           *
           * They are separated for readability.
           */
          uint32_t generation;
          bool dataClobbered;
          bool typeClobbered;
          bool hasDataReg;
          bool hasTypeReg;
          bool learnedType;
          RegisterID dataReg;
          RegisterID typeReg;
          JSValueType type;
  
          void reset(uint32_t gen) {
              dataClobbered = false;
              typeClobbered = false;
              hasDataReg = false;
              hasTypeReg = false;
              learnedType = false;
              generation = gen;
          }
      };
  
    public:
      ImmutableSync();
      ~ImmutableSync();
      bool init(JSContext *cx, const FrameState &frame, uint32_t nentries);
  
      void reset(Assembler *masm, Registers avail, FrameEntry *top, FrameEntry *bottom);
      void sync(FrameEntry *fe);
  
    private:
      void syncCopy(FrameEntry *fe);
      void syncNormal(FrameEntry *fe);
      RegisterID ensureDataReg(FrameEntry *fe, SyncEntry &e);
      RegisterID ensureTypeReg(FrameEntry *fe, SyncEntry &e);
  
      RegisterID allocReg();
      void freeReg(RegisterID reg);
  
      /* To be called only by allocReg. */
      RegisterID doAllocReg();
  
      inline SyncEntry &entryFor(FrameEntry *fe);
  
      bool shouldSyncType(FrameEntry *fe, SyncEntry &e);
      bool shouldSyncData(FrameEntry *fe, SyncEntry &e);
  
    private:
      JSContext *cx;
      SyncEntry *entries;
      const FrameState *frame;
      uint32_t nentries;
      Registers avail;
      Assembler *masm;
      SyncEntry *regs[Assembler::TotalRegisters];
      FrameEntry *top;
      FrameEntry *bottom;
      uint32_t generation;
  };
  
  } /* namespace mjit */
  } /* namespace js */
  
  #endif /* jsjaeger_imm_sync_h__ */
  
  