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From: "mikpe at it dot uu dot se" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/40178] New: libstdc++ fails to detect atomic builtins for EABI ARM/Linux Date: Sun, 17 May 2009 17:08:00 -0000 [thread overview] Message-ID: <bug-40178-7665@http.gcc.gnu.org/bugzilla/> (raw) EABI ARM/Linux supports atomic builtins in gcc, but they are implemented as calls to libgcc helper procedures with names like __sync_fetch_and_add_4() etc rather than being expanded inline. libstdc++v3/acinclude.m4 tests for atomic builtins by compiling source files with calls to __sync_fetch_and_add() etc, and then checking if the resulting assembly files contain the string "__sync__". If they do then acinclude.m4 assumes that atomic builtins are not supported. This presumably works for archs that inline expand the atomic builtins, but it gives false negatives on EABI ARM/Linux. Building gcc-4.4-20090512 for armv5tel-unknown-linux-gnueabi shows: ... Configuring in armv5tel-unknown-linux-gnueabi/libstdc++-v3 ... checking for thread model used by GCC... posix checking for atomic builtins for bool... no checking for atomic builtins for short... no checking for atomic builtins for int... no checking for atomic builtins for long long... no configure: WARNING: No native atomic operations are provided for this platform. configure: WARNING: They will be faked using a mutex. configure: WARNING: Performance of certain classes will degrade as a result. hppa-linux-gnu implements atomic builtins similarly to EABI ARM/Linux, so it may also be affected by this problem. -- Summary: libstdc++ fails to detect atomic builtins for EABI ARM/Linux Product: gcc Version: 4.4.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: mikpe at it dot uu dot se GCC host triplet: i686-pc-linux-gnu GCC target triplet: armv5tel-unknown-linux-gnueabi http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40178
next reply other threads:[~2009-05-17 17:08 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-05-17 17:08 mikpe at it dot uu dot se [this message] 2009-05-17 17:12 ` [Bug libstdc++/40178] " paolo dot carlini at oracle dot com 2009-05-17 18:01 ` mikpe at it dot uu dot se 2009-05-17 18:42 ` pinskia at gcc dot gnu dot org
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