view src/share/vm/opto/regalloc.cpp @ 2346:e1162778c1c8

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer. Reviewed-by: kvn, iveresov, never, tonyp, dholmes
author johnc
date Thu, 07 Apr 2011 09:53:20 -0700
parents c18cbe5936b8
children a7114d3d712e
line wrap: on
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/*
 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "opto/regalloc.hpp"

static const int NodeRegsOverflowSize = 200;

void (*PhaseRegAlloc::_alloc_statistics[MAX_REG_ALLOCATORS])();
int PhaseRegAlloc::_num_allocators = 0;
#ifndef PRODUCT
int PhaseRegAlloc::_total_framesize = 0;
int PhaseRegAlloc::_max_framesize = 0;
#endif

PhaseRegAlloc::PhaseRegAlloc( uint unique, PhaseCFG &cfg,
                              Matcher &matcher,
                              void (*pr_stats)() ):
               Phase(Register_Allocation), _cfg(cfg), _matcher(matcher),
               _node_oops(Thread::current()->resource_area()),
               _node_regs(0),
               _framesize(0xdeadbeef)
{
    int i;

    for (i=0; i < _num_allocators; i++) {
        if (_alloc_statistics[i] == pr_stats)
            return;
    }
    assert((_num_allocators + 1) < MAX_REG_ALLOCATORS, "too many register allocators");
    _alloc_statistics[_num_allocators++] = pr_stats;
}


//------------------------------reg2offset-------------------------------------
int PhaseRegAlloc::reg2offset_unchecked( OptoReg::Name reg ) const {
  // Slots below _max_in_arg_stack_reg are offset by the entire frame.
  // Slots above _max_in_arg_stack_reg are frame_slots and are not offset.
  int slot = (reg < _matcher._new_SP)
    ? reg - OptoReg::stack0() + _framesize
    : reg - _matcher._new_SP;
  // Note:  We use the direct formula (reg - SharedInfo::stack0) instead of
  // OptoReg::reg2stack(reg), in order to avoid asserts in the latter
  // function.  This routine must remain unchecked, so that dump_frame()
  // can do its work undisturbed.
  // %%% not really clear why reg2stack would assert here

  return slot*VMRegImpl::stack_slot_size;
}

int PhaseRegAlloc::reg2offset( OptoReg::Name reg ) const {

  // Not allowed in the out-preserve area.
  // In-preserve area is allowed so Intel can fetch the return pc out.
  assert( reg <  _matcher._old_SP ||
          (reg >= OptoReg::add(_matcher._old_SP,C->out_preserve_stack_slots()) &&
           reg <  _matcher._in_arg_limit) ||
          reg >=  OptoReg::add(_matcher._new_SP,C->out_preserve_stack_slots()),
          "register allocated in a preserve area" );
  return reg2offset_unchecked( reg );
}

//------------------------------offset2reg-------------------------------------
OptoReg::Name PhaseRegAlloc::offset2reg(int stk_offset) const {
  int slot = stk_offset / jintSize;
  int reg = (slot < (int) _framesize)
    ? slot + _matcher._new_SP
    : OptoReg::stack2reg(slot) - _framesize;
  assert(stk_offset == reg2offset((OptoReg::Name) reg),
         "offset2reg does not invert properly");
  return (OptoReg::Name) reg;
}

//------------------------------set_oop----------------------------------------
void PhaseRegAlloc::set_oop( const Node *n, bool is_an_oop ) {
  if( is_an_oop ) {
    _node_oops.set(n->_idx);
  }
}

//------------------------------is_oop-----------------------------------------
bool PhaseRegAlloc::is_oop( const Node *n ) const {
  return _node_oops.test(n->_idx) != 0;
}

// Allocate _node_regs table with at least "size" elements
void PhaseRegAlloc::alloc_node_regs(int size) {
  _node_regs_max_index = size + (size >> 1) + NodeRegsOverflowSize;
  _node_regs = NEW_RESOURCE_ARRAY( OptoRegPair, _node_regs_max_index );
  // We assume our caller will fill in all elements up to size-1, so
  // only the extra space we allocate is initialized here.
  for( uint i = size; i < _node_regs_max_index; ++i )
    _node_regs[i].set_bad();
}

#ifndef PRODUCT
void
PhaseRegAlloc::print_statistics() {
  tty->print_cr("Total frameslots = %d, Max frameslots = %d", _total_framesize, _max_framesize);
  int i;

  for (i=0; i < _num_allocators; i++) {
    _alloc_statistics[i]();
  }
}
#endif