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Re: [RFC] [PATCH] Introduce configure flag --with-stage1-cflags.
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Martin Liška <mliska at suse dot cz>
- Cc: Jakub Jelinek <jakub at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 19 Jun 2017 14:30:15 +0200
- Subject: Re: [RFC] [PATCH] Introduce configure flag --with-stage1-cflags.
- Authentication-results: sourceware.org; auth=none
- References: <41109217-1bf5-b112-e783-8040196fd410@suse.cz> <CAFiYyc0mXd8Wugs4cHUGaDRXnWdshV4NCURA4R+=3Nm=PtpFsw@mail.gmail.com> <20170526115155.GL8499@tucnak> <CAFiYyc0q8fKcSZ2FwKuXW7V_niNzN4kBUYouwwYUrkWkohx5Qg@mail.gmail.com> <b3c3fe8c-b8c6-ea19-df59-f2613dbf92e6@suse.cz> <f2a4a836-fad3-c3ec-02f9-03c71107fa9d@suse.cz>
On Mon, Jun 19, 2017 at 12:51 PM, Martin Liška <mliska@suse.cz> wrote:
> PING^1
>
> Richi are you fine with the suggested change? I basically followed your advises :)
Well, I am but as Eric disagrees I think we need input from other
people on this.
I'm comfortably setting STAGE1_CFLAGS here.
Richard.
> Martin
>
> On 05/26/2017 03:00 PM, Martin Liška wrote:
>> On 05/26/2017 01:55 PM, Richard Biener wrote:
>>> On Fri, May 26, 2017 at 1:51 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>>>> On Fri, May 26, 2017 at 01:46:47PM +0200, Richard Biener wrote:
>>>>> On Thu, May 25, 2017 at 11:23 AM, Martin Liška <mliska@suse.cz> wrote:
>>>>>> Hello.
>>>>>>
>>>>>> After a discussion with Richi, using adding "-O2" to STAGE1 cflags with a recent
>>>>>> enough compiler can significantly speed up bootstrap. Thus I'm suggesting to
>>>>>> introduce --with-stage1-cflags where one can provide such options.
>>>>>
>>>>> I don't think this is necessary -- you can always override with STAGE1_CFLAGS.
>>>>>
>>>>>> Apart from that, maybe it would be handy to automatically enable "-O2" when
>>>>>> one has a recent compiler? Do we have an example where we detect host compiler
>>>>>> and it's version?
>>>>>
>>>>> Don't know about version but configury already detects that we use GCC, so that
>>>>> knowledge should be readily available.
>>>>
>>>> Well, it certainly shouldn't be -O2 by default for any system GCC, more
>>>> something like if it is major of the configured configure minus 1 or newer
>>>> (or minus 2?), then use -O2, otherwise default to -O0 as before.
>>>
>>> I'd still default to -O0 on release branches regardless of version and then
>>> for development we can probably simply use "any GCC" when people have
>>> the chance to override.
>>
>> Ok, sending new patch that does that on experimental branches for ${CC} --version
>> being a GCC newer than 4.9.
>>
>> Martin
>>
>>>
>>> At least for me host GCC 4.8 works quite well with -O2.
>>>
>>> Richard.
>>>
>>>> Jakub
>>
>