Re: [PATCH 13/15] x86: add cmpxchg_flag() variant

[H. Peter Anvin]

On 08/23/2011 12:52 PM, Christoph Lameter wrote:
> 
> Should be relatively straightforward if you make the processor flag a
> builtin variable.
> 
> i.e. __processor_flag_zero, __processor_flag__gt etc.
> 
> Then the inline cmpxchg functions could simply do a
> 
> 	return __processor_flag_zero;
> 
> The code generator then needs to realize from the expression that we are
> referring to the zero flag and insert the correct jxx instruction.
>

The right thing is probably to have not the *flags* but the *conditions*
(exposed as variables):

bool __builtin_x86_s,  __builtin_x86_ns;
bool __builtin_x86_pe, __builtin_x86_po;
...


Or perhaps even

register bool x86_s asm("s");?

H.J. thoughts/ideas?

	-hpa
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