diff options
| author | Vineet Gupta <Vineet.Gupta1@synopsys.com> | 2016-11-07 16:31:38 -0800 |
|---|---|---|
| committer | Waldemar Brodkorb <wbx@uclibc-ng.org> | 2016-11-13 13:44:35 +0100 |
| commit | 0ef881ce9568e1c2e98351fdc067bebbc8c4696a (patch) | |
| tree | 40d30d60a00e117852f5cf39afdf470323f9fe1e /libc/sysdeps | |
| parent | f6cfc2129c6902410619f6cba56022af2977b6a3 (diff) | |
NPTL/ARC: implement __arch_exchange_32_acq using native EX
ARC EX instruction maps directly to this primitive, thus helps elide the
llock/scond based retry loop where possible.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'libc/sysdeps')
| -rw-r--r-- | libc/sysdeps/linux/arc/bits/atomic.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/arc/bits/atomic.h b/libc/sysdeps/linux/arc/bits/atomic.h index 1fdc83f70..48f37879c 100644 --- a/libc/sysdeps/linux/arc/bits/atomic.h +++ b/libc/sysdeps/linux/arc/bits/atomic.h @@ -58,3 +58,27 @@ void __arc_link_error (void); #define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \ ({ __arc_link_error (); oldval; }) + +/* Store NEWVALUE in *MEM and return the old value. + Atomic EX is present in all configurations + */ + +#define __arch_exchange_32_acq(mem, newval) \ + ({ \ + __typeof__(*(mem)) val = newval; \ + \ + __asm__ __volatile__( \ + "ex %0, [%1]" \ + : "+r" (val) \ + : "r" (mem) \ + : "memory" ); \ + \ + val; \ + }) + +#define atomic_exchange_acq(mem, newval) \ + ({ \ + if (sizeof(*(mem)) != 4) \ + abort(); \ + __arch_exchange_32_acq(mem, newval); \ + }) |