Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

From: Segher Boessenkool
Date: Fri Aug 17 2007 - 19:58:14 EST


#define forget(a) __asm__ __volatile__ ("" :"=m" (a) :"m" (a))

[ This is exactly equivalent to using "+m" in the constraints, as recently
explained on a GCC list somewhere, in response to the patch in my bitops
series a few weeks back where I thought "+m" was bogus. ]

[It wasn't explained on a GCC list in response to your patch, as
far as I can see -- if I missed it, please point me to an archived
version of it].

http://gcc.gnu.org/ml/gcc-patches/2007-07/msg01758.html

Ah yes, that old thread, thank you.

That's when _I_ came to know how GCC interprets "+m", but probably
this has been explained on those lists multiple times. Who cares,
anyway?

I just couldn't find the thread you meant, I thought I missed
have it, that's all :-)


Segher

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