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[Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add
- From: "dje at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 27 Jan 2012 14:27:25 +0000
- Subject: [Bug libstdc++/51798] [4.7 regression] libstdc++ atomicity performance regression due to __sync_fetch_and_add
- Auto-submitted: auto-generated
- References: <bug-51798-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51798
--- Comment #20 from David Edelsohn <dje at gcc dot gnu.org> 2012-01-27 14:27:25 UTC ---
Jonathan,
Your explanation in comment #16 does not fully explain the design of
libstdc++-v3. If the __sync_* intrinsics provide the complete abstraction for
CAS, what is the purpose of the custom implementations of atomicity.h in
libstdc++-v3/config/{cpu,os}/* ? One should not need those overrides if
__sync_* provides sufficient abstraction.
Jakub,
The patch is incomplete because it should update
src/libstdc++-v3/config/cpu/generic/atomicity_builtins/atomicity.h as well.