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Re: [PATCH, i386]: Add arch flag for sahf instruction

From: Uros Bizjak <ubizjak at gmail dot com>
To: "H. J. Lu" <hjl at lucon dot org>
Cc: Jan Hubicka <jh at suse dot cz>, Richard Henderson <rth at redhat dot com>, Jan Hubicka <hubicka at ucw dot cz>, GCC Patches <gcc-patches at gcc dot gnu dot org>
Date: Thu, 08 Mar 2007 18:26:33 +0100
Subject: Re: [PATCH, i386]: Add arch flag for sahf instruction
References: <5787cf470703080326r2ddebbc2y55bc1a84b1671cc3@mail.gmail.com> <20070308114046.GL470@kam.mff.cuni.cz> <20070308161140.GA22171@lucon.org>

H. J. Lu wrote:

The patch is fine with me, just I think H. J. should comment on whether -march=nocona should use sahf or not. I believe it is not only about very old prototypes, but also about early production machines. (at least my Nocna box does reject SAHF)
-march=nocona shouldn't use sahf. However, -machine=native should check the lahf_lm bit.

I have committed the patch after adding PTA_NO_SAHF to nocona processor flags.

Regarding -machine=native, I'll post a follow-up patch to solve this issue. FWIW, cmpxchg16 also has a cpuid flag, unhandled in current x86 driver.

Uros.

References:
- [PATCH, i386]: Add arch flag for sahf instruction
  - From: Uros Bizjak
- Re: [PATCH, i386]: Add arch flag for sahf instruction
  - From: Jan Hubicka
- Re: [PATCH, i386]: Add arch flag for sahf instruction
  - From: H. J. Lu

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