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Re: Enabling -frename-registers?
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Bernd Schmidt <bschmidt at redhat dot com>
- Cc: Jeffrey Law <law at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Segher Boessenkool <segher at kernel dot crashing dot org>
- Date: Fri, 29 Apr 2016 09:48:37 -0400
- Subject: Re: Enabling -frename-registers?
- Authentication-results: sourceware.org; auth=none
- References: <CAGWvnykBEjYMgOCaR_ZGLwB3fxPg-pB3WPSwAvmUBXzmXct8gg at mail dot gmail dot com> <57236285 dot 5090908 at redhat dot com> <CAGWvnykKwAtfSin23FP4L0bNgH4bSAdV+vMRTOe+dPk15oAfGg at mail dot gmail dot com> <57236547 dot 2070707 at redhat dot com>
On Fri, Apr 29, 2016 at 9:44 AM, Bernd Schmidt <bschmidt@redhat.com> wrote:
>
>
> On 04/29/2016 03:42 PM, David Edelsohn wrote:
>>
>> On Fri, Apr 29, 2016 at 9:32 AM, Bernd Schmidt <bschmidt@redhat.com>
>> wrote:
>>>
>>> On 04/29/2016 03:02 PM, David Edelsohn wrote:
>>>>
>>>>
>>>> How has this show general benefit for all architectures to deserve
>>>> enabling it by default at -O2?
>>>
>>>
>>>
>>> It should improve postreload scheduling in general, and it can also help
>>> clear up bad code generation left behind by register allocation.
>>
>>
>> Did you test the actual performance benefit on any architectures,
>> especially architectures other than x86?
>
>
> No. If that's the standard, I'll back out the change.
It seems rather strange to enable an optimization by default across
all targets without even knowing the performance impact.
I'm eager to learn the opinion of others about this.
Thanks, David