Re: [RFC] [PATCH] Introduce configure flag --with-stage1-cflags.

[Richard Biener <richard.guenther@gmail.com>]

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
>>
>