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| author | Richard Henderson <rth@redhat.com> | 2014-02-20 16:11:43 -0800 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2014-02-20 16:11:43 -0800 |
| commit | 2fdc29e8c7f95019aecdcbed5b556c82dbd91c7c (patch) | |
| tree | 6623a57d7a1b9906bd2dfda145c31783f15dd8c8 | |
| parent | aa637f667f9c6b5f96af8c96c956f58041cdb2ba (diff) | |
| download | gcc-2fdc29e8c7f95019aecdcbed5b556c82dbd91c7c.zip gcc-2fdc29e8c7f95019aecdcbed5b556c82dbd91c7c.tar.gz gcc-2fdc29e8c7f95019aecdcbed5b556c82dbd91c7c.tar.bz2 | |
re PR c++/60272 (atomic<>::compare_exchange_weak has spurious store and can cause race conditions)
PR c++/60272
* builtins.c (expand_builtin_atomic_compare_exchange): Always make
a new pseudo for OLDVAL.
From-SVN: r207972
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/builtins.c | 7 |
2 files changed, 11 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index cbdecf8..c51d139 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2014-02-20 Richard Henderson <rth@redhat.com> + + PR c++/60272 + * builtins.c (expand_builtin_atomic_compare_exchange): Always make + a new pseudo for OLDVAL. + 2014-02-20 Jakub Jelinek <jakub@redhat.com> PR target/57896 diff --git a/gcc/builtins.c b/gcc/builtins.c index 09fefe50..35969ad 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -5332,9 +5332,12 @@ expand_builtin_atomic_compare_exchange (enum machine_mode mode, tree exp, if (target == const0_rtx) target = NULL; - oldval = expect; - if (!expand_atomic_compare_and_swap (&target, &oldval, mem, oldval, desired, + /* Lest the rtl backend create a race condition with an imporoper store + to memory, always create a new pseudo for OLDVAL. */ + oldval = NULL; + + if (!expand_atomic_compare_and_swap (&target, &oldval, mem, expect, desired, is_weak, success, failure)) return NULL_RTX; |