target/5858: atomicity.h support for -fcheck-memory_usage

[salevin at lgc dot com]

>Number:         5858
>Category:       target
>Synopsis:       atomicity.h  support for -fcheck-memory_usage
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 06 14:46:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Stewart A. Levin
>Release:        gcc 3.0.4
>Organization:
>Environment:
linux RH 7.2, i686 PC
>Description:
Using mpatrol to try to detect the cause of some intermittent
seg-faults, I ran into a compiler complaint using the
-fcheck-memory-usage flag that it couldn't be used with
asm() code.

To work around it, I copied the 486 bits/atomicity.h to
a separate tree and edited it to apply the

__no_check_memory_usage__

attribute in addition to the existing __unused__ attribute
for these two short assembly routines.  I've inserted it
below, modified from the 1.5 version, since it is such
a short header file.

I understand from browsing a couple of other reports
about the same compiler complaint that -fcheck-memory-usage
is currently unsupported, presumably because development
of GNU Checker stopped with gcc 2.7-something.  The
mpatrol hooks do work properly at this time though,
and the lack of Rational's Purify product for linux
makes this at least a viable fallback.

>How-To-Repeat:

>Fix:
// Low-level functions for atomic operations: x86, x >= 4 version  -*- C++ -*-

// Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library 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 for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

#ifndef _BITS_ATOMICITY_H
#define _BITS_ATOMICITY_H       1

typedef int _Atomic_word;

static inline _Atomic_word 
__attribute__ ((__unused__,__no_check_memory_usage__))
__exchange_and_add (volatile _Atomic_word *__mem, int __val);

static inline _Atomic_word 
__exchange_and_add (volatile _Atomic_word *__mem, int __val)
{
  register _Atomic_word __result;
  __asm__ __volatile__ ("lock; xaddl %0,%2"
                        : "=r" (__result) 
                        : "0" (__val), "m" (*__mem) 
                        : "memory");
  return __result;
}

static inline void
__attribute__ ((__unused__,__no_check_memory_usage__))
__atomic_add (volatile _Atomic_word* __mem, int __val);

static inline void
__atomic_add (volatile _Atomic_word* __mem, int __val)
{
  __asm__ __volatile__ ("lock; addl %0,%1"
                        : : "ir" (__val), "m" (*__mem) : "memory");
}

#endif /* atomicity.h */
>Release-Note:
>Audit-Trail:
>Unformatted: