libstdc++/4367: Sparc atomicity.h routines can lock up on some OS.

[Richard Henderson]

The following reply was made to PR libstdc++/4367; it has been noted by GNATS.

From: Richard Henderson <rth@redhat.com>
To: bkoz@gcc.gnu.org, eric.norum@usask.ca, gcc-bugs@gcc.gnu.org,
   gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: libstdc++/4367: Sparc atomicity.h routines can lock up on some OS.
Date: Tue, 2 Apr 2002 00:08:05 -0800

 On Tue, Apr 02, 2002 at 02:56:22AM -0000, bkoz@gcc.gnu.org wrote:
 >     I guess you'll have to use heavier-weight locks for these OS's.
 >     Can you think of another solution? I cannot. 
 
 Generally for these targets you turn off interrupts.  See
 the m68k atomicity.h, for instance.
 
 >     Note this is an issue with all the cpu/atomicity.h files,
 >     not just sparc, right?
 
 No, only those cpu's that have to use spinlocks instead of
 e.g. an atomic-add, compare-and-exchange, or load-locked
 instruction.
 
 Of those listed in config/*, Sparc v7/v8, m68000, MIPS I,
 and PA are affected.
 
 MIPS I is an odd-ball because some operating systems (eg Linux)
 provide emulation for the MIPS II ll/sc instructions.  Currently
 our atomicity.h file assumes MIPS II.
 
 
 r~