Re: ASM flags in general

From: H. Peter Anvin
Date: Mon Jul 27 2015 - 17:14:37 EST


On 07/27/2015 01:01 PM, Uros Bizjak wrote:
> On Mon, Jul 27, 2015 at 9:04 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
>> I wonder if using "set" would be a performance regression over "sbb" for
>> the existing bitops, in which case it would slot quite nicely into this
>> scheme.
>
> As far as I have looked into the compiled code, following sequence was
> produced when the value was directly used as bool
>
[...]
>
> vs. new sequence:
>

You misunderstood me: I was referring to *old* versions of gcc (â 5); in
order words: can we use the macros I proposed instead of #ifdef? For
gcc 6+ we obviously want to use the flags output.

-hpa

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