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From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/50065] -Os, -O2, -O3 optimization breaks LD/ST ordering on 32-bit SPARC Date: Sun, 14 Aug 2011 13:00:00 -0000 [thread overview] Message-ID: <bug-50065-4-ZtvmtHYjZs@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-50065-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50065 --- Comment #6 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-08-14 12:42:47 UTC --- > The code is equivalent to > > volatile unsigned char lock; > int remap_barrier; > > while (atomic_test_and_set(lock)) { > while (lock) { > ; > } > } > remap_barrier++; > lock = 0; > > Eric: could you let me know you you think the code inside function > spinlock_lock(&remap_lock) is a NOP? I don't, you simply misquoted, I wrote "the end of the code". The first part of the spinlock implementation is correct, in particular you have the required memory barrier in spinlock_is_locked. The second part is not correct, as you don't have the memory barrier in spinlock_unlock. > Also, the arch_write_lock/unlock in the SPARC port of Linux uses a very > similar implementation. No, it precisely doesn't, it has the memory barrier in spinlock_unlock.
next prev parent reply other threads:[~2011-08-14 12:43 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-08-12 21:49 [Bug c/50065] New: " tanzhangxi at gmail dot com 2011-08-13 4:33 ` [Bug rtl-optimization/50065] " pinskia at gcc dot gnu.org 2011-08-13 10:12 ` ebotcazou at gcc dot gnu.org 2011-08-14 1:30 ` tanzhangxi at gmail dot com 2011-08-14 4:42 ` tanzhangxi at gmail dot com 2011-08-14 9:38 ` mikpe at it dot uu.se 2011-08-14 13:00 ` ebotcazou at gcc dot gnu.org [this message] 2011-08-14 13:11 ` ebotcazou at gcc dot gnu.org 2011-08-14 22:43 ` tanzhangxi at gmail dot com 2011-08-15 8:52 ` ebotcazou at gcc dot gnu.org 2011-08-16 7:29 ` mikpe at it dot uu.se
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