[gcc r14-1465] libstdc++: optimize EH phase 2

[Jason Merrill]

https://gcc.gnu.org/g:5d9c9119079ef14798b0a4fc771fd8d3905ec746

commit r14-1465-g5d9c9119079ef14798b0a4fc771fd8d3905ec746
Author: Jason Merrill <jason@redhat.com>
Date:   Wed May 31 15:02:05 2023 -0400

    libstdc++: optimize EH phase 2
    
    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.

Diff:
---
 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.