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From: "i at maskray dot me" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug driver/100937] configure: Add --enable-default-semantic-interposition
Date: Sun, 06 Jun 2021 23:15:26 +0000 [thread overview]
Message-ID: <bug-100937-4-zoDfXTQgQH@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-100937-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100937
Fangrui Song <i at maskray dot me> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|WONTFIX |---
Status|RESOLVED |UNCONFIRMED
--- Comment #2 from Fangrui Song <i at maskray dot me> ---
How is it a portability problem?
clang -fpic has always been allowing interprocedural optimizations for
non-vague-linkage function definitions. FreeBSD uses clang and software works
with no problem.
For a vague-linkage function definition, a call site in the same
translation unit may inline the callee. Whether
-fno-semantic-interposition is enabled/disabled has no effect.
For a non-vague-linkage function definition, by default
(-fsemantic-interposition) the -fpic mode does not allow a call site
in the same translation unit to inline the callee or perform other
interprocedural optimizations.
-fno-semantic-interposition re-enables interprocedural optimizations.
If a caller inlines a callee, using LD_PRELOAD to interpose the callee
will not affect the caller. But many other LD_PRELOAD usage still
work.
We consider the small LD_PRELOAD limitation a good trade off for the speedup.
next prev parent reply other threads:[~2021-06-06 23:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-06 23:10 [Bug driver/100937] New: " i at maskray dot me
2021-06-06 23:12 ` [Bug driver/100937] " pinskia at gcc dot gnu.org
2021-06-06 23:15 ` i at maskray dot me [this message]
2021-06-06 23:19 ` pinskia at gcc dot gnu.org
2021-06-06 23:27 ` pinskia at gcc dot gnu.org
2021-06-07 8:28 ` jakub at gcc dot gnu.org
2021-06-10 5:02 ` i at maskray dot me
2021-11-02 18:16 ` frankhb1989 at gmail dot com
2021-11-03 3:19 ` egallager at gcc dot gnu.org
2021-11-03 12:25 ` redi at gcc dot gnu.org
2021-11-22 13:26 ` frankhb1989 at gmail dot com
2021-11-22 19:52 ` i at maskray dot me
2021-11-22 22:54 ` Jan Hubicka
2021-11-22 22:54 ` hubicka at kam dot mff.cuni.cz
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