view src/share/vm/runtime/stackValueCollection.cpp @ 1716:be3f9c242c9d

6948538: CMS: BOT walkers can fall into object allocation and initialization cracks Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode. Reviewed-by: chrisphi, johnc, poonam
author ysr
date Mon, 16 Aug 2010 15:58:42 -0700
parents c18cbe5936b8
children f95d63e2154a
line wrap: on
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/*
 * Copyright (c) 2001, 2005, 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 "incls/_precompiled.incl"
# include "incls/_stackValueCollection.cpp.incl"

jint StackValueCollection::int_at(int slot) const {
  intptr_t val =  at(slot)->get_int();
  jint ival = *((jint*) (&val));
  return ival;
}

jlong StackValueCollection::long_at(int slot) const {
#ifdef _LP64
  return at(slot+1)->get_int();
#else
  union {
    jlong jl;
    jint  array[2];
  } value;
  // Interpreter stack is reversed in memory:
  // low memory location is in higher java local slot.
  value.array[0] = at(slot+1)->get_int();
  value.array[1] = at(slot  )->get_int();
  return value.jl;
#endif
}

Handle StackValueCollection::obj_at(int slot) const {
  return at(slot)->get_obj();
}

jfloat StackValueCollection::float_at(int slot) const {
  intptr_t res = at(slot)->get_int();
  return *((jfloat*) (&res));
}

jdouble StackValueCollection::double_at(int slot) const {
#ifdef _LP64
  intptr_t res = at(slot+1)->get_int();
  return *((jdouble*) (&res));
#else
  union {
    jdouble jd;
    jint    array[2];
  } value;
  // Interpreter stack is reversed in memory:
  // low memory location is in higher java local slot.
  value.array[0] = at(slot+1)->get_int();
  value.array[1] = at(slot  )->get_int();
  return value.jd;
#endif
}

void StackValueCollection::set_int_at(int slot, jint value) {
  intptr_t val;
  *((jint*) (&val)) = value;
  at(slot)->set_int(val);
}

void StackValueCollection::set_long_at(int slot, jlong value) {
#ifdef _LP64
  at(slot+1)->set_int(value);
#else
  union {
    jlong jl;
    jint  array[2];
  } x;
  // Interpreter stack is reversed in memory:
  // low memory location is in higher java local slot.
  x.jl = value;
  at(slot+1)->set_int(x.array[0]);
  at(slot+0)->set_int(x.array[1]);
#endif
}

void StackValueCollection::set_obj_at(int slot, Handle value) {
  at(slot)->set_obj(value);
}

void StackValueCollection::set_float_at(int slot, jfloat value) {
#ifdef _LP64
  union {
    intptr_t jd;
    jint    array[2];
  } val;
  // Interpreter stores 32 bit floats in first half of 64 bit word.
  val.array[0] = *(jint*)(&value);
  val.array[1] = 0;
  at(slot)->set_int(val.jd);
#else
  at(slot)->set_int(*(jint*)(&value));
#endif
}

void StackValueCollection::set_double_at(int slot, jdouble value) {
#ifdef _LP64
  at(slot+1)->set_int(*(intptr_t*)(&value));
#else
  union {
    jdouble jd;
    jint    array[2];
  } x;
  // Interpreter stack is reversed in memory:
  // low memory location is in higher java local slot.
  x.jd = value;
  at(slot+1)->set_int(x.array[0]);
  at(slot+0)->set_int(x.array[1]);
#endif
}

#ifndef PRODUCT
void StackValueCollection::print() {
  for(int index = 0; index < size(); index++) {
    tty->print("\t  %2d ", index);
    at(index)->print_on(tty);
    if( at(index  )->type() == T_INT &&
        index+1 < size() &&
        at(index+1)->type() == T_INT ) {
      tty->print("  " INT64_FORMAT " (long)", long_at(index));
      tty->cr();
      tty->print("\t     %.15e (double)", double_at(index));
      tty->print("  " PTR64_FORMAT " (longhex)", long_at(index));
    }
    tty->cr();
  }
}
#endif