From: Petri Latvala <petri.latvala@intel.com>
To: Lyude <lyude@redhat.com>
Cc: igt-dev@lists.freedesktop.org
Subject: Re: [igt-dev] [PATCH i-g-t 4/4] meson: Add -fcommon to cc_flags
Date: Tue, 17 Mar 2020 08:34:15 +0200 [thread overview]
Message-ID: <20200317063415.GF9497@platvala-desk.ger.corp.intel.com> (raw)
In-Reply-To: <20200316161132.29833-5-lyude@redhat.com>
On Mon, Mar 16, 2020 at 12:11:32PM -0400, Lyude wrote:
> From: Lyude Paul <lyude@redhat.com>
>
> Now that we've fixed a bunch of build breakages on systems where
> -fcommon is the default (gcc 10+), let's start building with -fcommon by
> default so we can make sure things don't break with this in the future.
> Supposedly it's supposed to be able to generate better code anyway!
The documentation claims otherwise, "on many targets implies a speed
and code size penalty on global variable references". In fact the
documentation even claims you get the multiple definition errors for
variables with -fno-common and -fcommon helps avoiding them in legacy
code! It's completely backwards to what happens. Oh well.
With that said, the code was clearly wrong, thanks for the series.
>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Petri Latvala <petri.latvala@intel.com>
What this series proves is that no one is able to understand how
tentative definitions and tentative declarations work in C.
--
Petri Latvala
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next prev parent reply other threads:[~2020-03-17 6:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-16 16:11 [igt-dev] [PATCH i-g-t 0/4] Fixes for GCC 10's -fcommon default Lyude
2020-03-16 16:11 ` [igt-dev] [PATCH i-g-t 1/4] lib/igt_core: Make igt_subtest_jmpbuf/igt_dynamic_jmpbuf extern Lyude
2020-03-16 23:11 ` Chris Wilson
2020-03-16 16:11 ` [igt-dev] [PATCH i-g-t 2/4] lib/rendercopy_gen*: Make cc/viewport static Lyude
2020-03-16 23:11 ` Chris Wilson
2020-03-16 16:11 ` [igt-dev] [PATCH i-g-t 3/4] assembler/gen4asm.h: Make struct src_operand extern Lyude
2020-03-16 23:08 ` Chris Wilson
2020-03-17 16:56 ` Lyude Paul
2020-03-19 17:29 ` Lyude Paul
2020-03-16 23:10 ` Chris Wilson
2020-03-19 17:40 ` [igt-dev] [PATCH i-g-t v2] assembler/gen4asm.h: Remove struct src_operand src_operand variable Lyude
2020-03-20 12:24 ` Petri Latvala
2020-03-16 16:11 ` [igt-dev] [PATCH i-g-t 4/4] meson: Add -fcommon to cc_flags Lyude
2020-03-17 6:34 ` Petri Latvala [this message]
2020-03-16 17:16 ` [igt-dev] ✓ Fi.CI.BAT: success for Fixes for GCC 10's -fcommon default Patchwork
2020-03-17 0:39 ` [igt-dev] ✗ Fi.CI.IGT: failure " Patchwork
2020-03-19 18:59 ` [igt-dev] ✗ Fi.CI.BAT: failure for Fixes for GCC 10's -fcommon default (rev2) Patchwork
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