diff mbox

X86-64: Add -mskip-rax-setup

Message ID CAMe9rOpuXiUXTU30pyr+v9Z0dVCzh=_gdCCTataziSuJ_JMwVw@mail.gmail.com
State New
Headers show

Commit Message

H.J. Lu Dec. 18, 2014, 5:43 p.m. UTC 
On Thu, Dec 18, 2014 at 9:23 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Thu, Dec 18, 2014 at 6:08 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 12/18/2014 06:12 AM, Uros Bizjak wrote:
>>>>>
>>>>> # temporary until string.h is fixed
>>>>> KBUILD_CFLAGS += -ffreestanding
>>>>>
>>>>> Yes, it looks to me that new option is the way to go.
>>>>
>>>> Is this an OK?
>>>
>>> In principle, I'm OK with the patch approach, but let's wait for
>>> eventual comments from Linux people.
>>>
>>
>> Acked-by: H. Peter Anvin <hpa@linux.intel.com>
>>
>> H.J. already coordinated with us; we are more than happy with this approach.
>
> Great, I'm glad that this specialized option has uses.
>
> Patch is OK.

It is in now.  Here is the GCC 5 change entry.  OK to install?

Peter, please feel free to use my kernel patch or create a different
one.

Thanks.

Comments

H. Peter Anvin Dec. 18, 2014, 5:44 p.m. UTC | #1 
On 12/18/2014 09:43 AM, H.J. Lu wrote:
> 
> Peter, please feel free to use my kernel patch or create a different
> one.
> 

Great, thanks!

	-hpa
Rasmus Villemoes Dec. 18, 2014, 6:37 p.m. UTC | #2 
On Thu, Dec 18 2014, "H. Peter Anvin" <hpa@zytor.com> wrote:

> On 12/18/2014 09:43 AM, H.J. Lu wrote:
>> 
>> Peter, please feel free to use my kernel patch or create a different
>> one.
>> 
>
> Great, thanks!
>

Thanks for accepting this idea, and especially to H.J. for already
having done all the work.

Minor thing: If it's not too late, I'd appreciate a 'Suggested-by' or
similar mention in the kernel change log.

Thanks,
Rasmus
H. Peter Anvin Dec. 18, 2014, 6:38 p.m. UTC | #3 
On 12/18/2014 10:37 AM, Rasmus Villemoes wrote:
> 
> Minor thing: If it's not too late, I'd appreciate a 'Suggested-by' or
> similar mention in the kernel change log.
> 

I think we can get that.

	-hpa
Mike Stump Dec. 18, 2014, 7:22 p.m. UTC | #4 
On Dec 18, 2014, at 9:43 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> + arguments passed in vector registers.  This can be used to
> + optimize Linux kernel.</li>

English, to optimize _the_ Linux kernel?
diff mbox

Patch

Index: gcc-5/changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v
retrieving revision 1.52
diff -u -p -r1.52 changes.html
--- gcc-5/changes.html 15 Dec 2014 19:55:08 -0000 1.52
+++ gcc-5/changes.html 18 Dec 2014 17:42:18 -0000
@@ -444,6 +444,10 @@  void operator delete[] (void *, std::siz
  place of the __fentry__ or mcount call, so that a call per function
  can be later patched in. This can be used for low overhead tracing or
  hot code patching.</li>
+ <li>The new <code>-mskip-rax-setup</code> option to skip setting
+ up RAX register when SSE is disabled and there are no variable
+ arguments passed in vector registers.  This can be used to
+ optimize Linux kernel.</li>
   </ul>

 <h3 id="sh">SH</h3>