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Message-ID: <20160327222745.GD21636@brightrain.aerifal.cx> Date: Sun, 27 Mar 2016 18:27:45 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: [PATCH 1/2] add 64bit atomics on top of 64bit ll/sc primitives On Sun, Mar 27, 2016 at 04:20:18PM -0500, Bobby Bingham wrote: > --- > src/internal/atomic.h | 28 ++++++++++++++++++++++++++++ > 1 file changed, 28 insertions(+) > > diff --git a/src/internal/atomic.h b/src/internal/atomic.h > index 6f37d25..43a8a00 100644 > --- a/src/internal/atomic.h > +++ b/src/internal/atomic.h > @@ -99,6 +99,34 @@ static inline void *a_cas_p(volatile void *p, void *t, void *s) > > #endif > > +#ifdef a_ll_64 > + > +#ifndef a_and_64 > +#define a_and_64 a_and_64 > +static inline void a_and_64(volatile uint64_t *p, uint64_t v) > +{ > + uint64_t old; > + a_pre_llsc(); > + do old = a_ll_64(p); > + while (!a_sc_64(p, old & v)); > + a_post_llsc(); > +} > +#endif > + > +#ifndef a_or_64 > +#define a_or_64 a_or_64 > +static inline void a_or_64(volatile uint64_t *p, uint64_t v) > +{ > + uint64_t old; > + a_pre_llsc(); > + do old = a_ll_64(p); > + while (!a_sc_64(p, old | v)); > + a_post_llsc(); > +} > +#endif I think we can do without these. a_and_64 and a_or_64 are simply misnamed (they're only usable as atomic bitset/bitclear, not necessarily atomic on the whole 64-bit unit since they only operate on one bit at a time) and I don't think there's any measurable gain to be had by doing them with 64-bit hardware atomics. They'll probably be dropped at some point in the future anyway; malloc is essentially the only user. Rich
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