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Re: [PATCH, i386] RTM support
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: Kirill Yukhin <kirill dot yukhin at gmail dot com>, gcc-patches List <gcc-patches at gcc dot gnu dot org>, Jakub Jelinek <jakub at redhat dot com>, "H.J. Lu" <hjl dot tools at gmail dot com>
- Date: Mon, 5 Mar 2012 19:04:47 +0100
- Subject: Re: [PATCH, i386] RTM support
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On Mon, Mar 5, 2012 at 6:12 PM, Andi Kleen <andi@firstfloor.org> wrote:
> On Mon, Mar 05, 2012 at 03:31:32PM +0400, Kirill Yukhin wrote:
>> Adding patch
>
> I would still remove the "-mrtm" option. I never understood what options
> for intrinsics are good for. They are just a pain to add to Makefiles,
> but don't give any benefit.
Without -mrtm, the test will just emit a call to
__builtin_ia32_xbegin, for instance. You would ge linking error from
your app.
And the reason to have -mXXX flags is quite obvious. You don't want
combiner to optimize the sequence of two supported instructions (SSE
level X, for example) to an unsupported one (SSE level X+N) that
implements the same functionality. The same goes for integer
instructions, but less obvious ;)
So, I'm afraid that -mXXX options stay. But you can sprinkle target
option pragmas around the code now.
Uros.