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bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilati
From: |
Deus Max |
Subject: |
bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation |
Date: |
Sat, 24 Jun 2023 12:17:11 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
On 2023-06-23T15:15 Fri, Eli Zaretskii wrote:
>> From: Arash Esbati <arash@gnu.org>
>> Cc: Andrea Corallo <acorallo@gnu.org>, cyril.arnould@outlook.com,
>> 63365@debbugs.gnu.org, svraka.andras@gmail.com
>> Date: Fri, 23 Jun 2023 13:41:10 +0200
>>
>> > Also, why are you using -O3? That is not recommended when building
>> > Emacs.
>>
>> I wasn't aware of that. Can you elaborate why -O3 isn't recommended?
>
> In a nutshell, it bloats the code (due to excessive inlining), with no
> real effect on speed. The inner loops in Emacs are very large, and
> thus the techniques used by -O3 to speed up code (loop unrolling etc.)
> don't really work. Moreover, they could make things worse because the
> larger loops might no longer fit into the L1 cache of the CPU.
>
> The -O3 is well suited to speed up relatively simple algorithms with
> tight loops. Emacs has very few of those, in the places that matter
> for observable performance.
Interesting.
This recommendation and the explanation are worth documenting somewhere.
Shouldn't a new bug be opened on documenting the GCC -O3 recommendation?
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, (continued)
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Arash Esbati, 2023/06/08
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Cyril Arnould, 2023/06/16
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Arash Esbati, 2023/06/22
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/23
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Arash Esbati, 2023/06/23
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/23
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Arash Esbati, 2023/06/23
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation,
Deus Max <=
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/24
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Deus Max, 2023/06/24
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/24
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Andrea Corallo, 2023/06/25
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/25
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Andrea Corallo, 2023/06/25
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Eli Zaretskii, 2023/06/25
- bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Andrea Corallo, 2023/06/26
bug#63365: 30.0.50; GCC 13.1 breaks building Emacs with native-compilation, Cyril Arnould, 2023/06/17