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Re: [PATCH, i386]: Implement -mcmpxchg16b and -msahf options
On Tue, Mar 13, 2007 at 04:30:47PM +0100, Jan Hubicka wrote:
> > +@item -mcmpxchg16b
> > +@opindex -mcmpxchg16b
> > +This option will enable GCC to use CMPXCHG16B instruction in generated code.
Wouldn't -mcx16 be a better name? That's how the feature bit is called...
> Perhaps little extra information can be put here. Average user looking
> for flags to speed up his application will have no idea what CMPXCHG16B
> is used for and thus we can save his time spent by looking for docs or
> unnecesary benchmarking if his 3d FPS now runs cooler.
> I would add wikipedia's explanation "CMPXCHG16B allows for atomic
> operations on 128-bit double quadword (or oword) data types. This is
> useful for high resolution counters that could be updated by multiple
> processors (or cores)." and reference to GCC atomic builtins.
And #pragma omp atomic on long double variables.
Jakub