x86 code generation question

[Florian Weimer]

Jack Lloyd <lloyd@randombit.net> writes:

> On Thu, Apr 29, 2004 at 05:03:19PM -0400, Paul Koning wrote:
>
>> Given a machine with conditional move instructions, either version
>> should translate into straight line code with conditional moves, but
>> (apparently -- I'm no x86 expert) the x86 isn't one of those.  Arm and
>> Alpha are, though.
>
> IIRC x86 has cmov in ppro and up, so it's possible the OP just needs
> to use -march=i586 (or up) to get the desired behavior. It seems
> unlikely that GCC would not know about i586 instructions, though the
> optimizer might not be able to use cmov well due to register
> pressure.

CMOV is a Pentium Pro feature, so you have to use -march=pentiumpro
(maybe -march=i686 works as well, I haven't checked).  If you activate
this option, GCC can and does generate CMOV instructions.

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