[PATCH] libstdc++: optimize EH phase 2
Jason Merrill
jason@redhat.com
Thu Jun 1 03:12:55 GMT 2023
Tested x86_64-pc-linux-gnu, OK for trunk?
-- 8< --
In the ABI's two-phase EH model, first we walk the stack looking for a
handler, then we walk the stack running cleanups until we reach that
handler. In the cleanup phase, we shouldn't redundantly check the handlers
along the way, e.g. when walking through g():
void f() { throw 42; }
void g() { try { f(); } catch (void *) { } }
int main() { try { g(); } catch (int) { } }
libstdc++-v3/ChangeLog:
* libsupc++/eh_personality.cc (PERSONALITY_FUNCTION): Don't check
handlers in the cleanup phase.
---
libstdc++-v3/libsupc++/eh_personality.cc | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/libstdc++-v3/libsupc++/eh_personality.cc b/libstdc++-v3/libsupc++/eh_personality.cc
index 12391e563d6..cc6bc048892 100644
--- a/libstdc++-v3/libsupc++/eh_personality.cc
+++ b/libstdc++-v3/libsupc++/eh_personality.cc
@@ -592,6 +592,10 @@ PERSONALITY_FUNCTION (int version,
// Zero filter values are cleanups.
saw_cleanup = true;
}
+ else if (actions == _UA_CLEANUP_PHASE)
+ // We checked the handlers in the search phase; if one of them
+ // matched, actions would also have _UA_HANDLER_FRAME set.
+ ;
else if (ar_filter > 0)
{
// Positive filter values are handlers.
base-commit: 68816ba245afc6d0e1482bde2d15b35b925b4195
--
2.31.1
More information about the Libstdc++
mailing list