From: "marxin.liska at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: dwz@sourceware.org
Subject: [Bug default/24965] [dwz] Faster hashing using native insns
Date: Tue, 01 Jan 2019 00:00:00 -0000 [thread overview]
Message-ID: <bug-24965-11298-N9BK7Ff8iv@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-24965-11298@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=24965
--- Comment #5 from Martin Liška <marxin.liska at gmail dot com> ---
(In reply to Jakub Jelinek from comment #4)
> This looks wrong to me. It will fail to compile on non-x86, fail to run on
> x86 on older hw, and it is unclear why an option is needed.
Sure, it should be conditional for x86_64.
> It needs to be
> guarded with preprocessor autoconf macros on whether the insns are available
> (assembler handles them) and runtime check whether it can be used or not.
> Formatting glitches too (missing space before ( ).
And the detection should be run-time, so we can use target_clone attribute:
__attribute__((target_clones ("default", "sse42"))) or set guard at the start
up:
#include <config/i386/cpuinfo.h>
...
guard = ((__cpu_model.__cpu_features[0] & (1 << FEATURE_AVX4_2))
which would be faster as we'll not use indirect calls.
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prev parent reply other threads:[~2019-09-05 11:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-01 0:00 [Bug default/24965] New: " vries at gcc dot gnu.org
2019-01-01 0:00 ` [Bug default/24965] " marxin.liska at gmail dot com
2019-01-01 0:00 ` vries at gcc dot gnu.org
2019-01-01 0:00 ` vries at gcc dot gnu.org
2019-01-01 0:00 ` marxin.liska at gmail dot com
2019-01-01 0:00 ` jakub at redhat dot com
2019-01-01 0:00 ` vries at gcc dot gnu.org
2019-01-01 0:00 ` jakub at redhat dot com
2019-01-01 0:00 ` jakub at redhat dot com
2019-01-01 0:00 ` marxin.liska at gmail dot com [this message]
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