From d86e37524da30190b22017cc46a278c3ebfceb5c Mon Sep 17 00:00:00 2001 From: rth Date: Thu, 20 Feb 2014 17:43:53 +0000 Subject: PR c++/60272 gcc/ * builtins.c (expand_builtin_atomic_compare_exchange): Conditionalize on failure the store back into EXPECT. libatomic/ * cas_n.c (libat_compare_exchange): Conditionalize on failure the store back to EPTR. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@207966 138bc75d-0d04-0410-961f-82ee72b054a4 --- libatomic/ChangeLog | 6 ++++++ libatomic/cas_n.c | 25 ++++++++++++------------- 2 files changed, 18 insertions(+), 13 deletions(-) (limited to 'libatomic') diff --git a/libatomic/ChangeLog b/libatomic/ChangeLog index 2d1c9bd18ae..1bd3c2178aa 100644 --- a/libatomic/ChangeLog +++ b/libatomic/ChangeLog @@ -1,3 +1,9 @@ +2014-02-20 Richard Henderson + + PR c++/60272 + * cas_n.c (libat_compare_exchange): Conditionalize on failure + the store back to EPTR. + 2014-01-02 Richard Sandiford Update copyright years diff --git a/libatomic/cas_n.c b/libatomic/cas_n.c index 39c78332423..801262d551c 100644 --- a/libatomic/cas_n.c +++ b/libatomic/cas_n.c @@ -51,10 +51,9 @@ SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, #if !DONE && N <= WORDSIZE && defined(atomic_compare_exchange_w) bool SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, - int smodel, int fmodel UNUSED) + int smodel, int fmodel) { UWORD mask, shift, weval, woldval, wnewval, t, *wptr; - bool ret = false; pre_barrier (smodel); @@ -82,12 +81,13 @@ SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, } while (!atomic_compare_exchange_w (wptr, &woldval, t, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED)); - ret = true; + post_barrier (smodel); + return true; + failure: *eptr = woldval >> shift; - - post_barrier (smodel); - return ret; + post_barrier (fmodel); + return false; } #define DONE 1 @@ -102,18 +102,17 @@ SIZE(libat_compare_exchange) (UTYPE *mptr, UTYPE *eptr, UTYPE newval, { UTYPE oldval; UWORD magic; - bool ret = false; + bool ret; pre_seq_barrier (smodel); magic = protect_start (mptr); oldval = *mptr; - if (oldval == *eptr) - { - *mptr = newval; - ret = true; - } - *eptr = oldval; + ret = (oldval == *eptr); + if (ret) + *mptr = newval; + else + *eptr = oldval; protect_end (mptr, magic); post_seq_barrier (smodel); -- cgit v1.2.1