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[130.44.146.16]) by smtp.gmail.com with ESMTPSA id mn6-20020a0562145ec600b005ef442226bbsm6793419qvb.8.2023.05.31.20.12.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 May 2023 20:12:57 -0700 (PDT) To: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org Subject: [PATCH] libstdc++: optimize EH phase 2 Date: Wed, 31 May 2023 23:12:55 -0400 Message-Id: <20230601031255.1268906-1-jason@redhat.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Jason Merrill via Gcc-patches From: Jason Merrill Reply-To: Jason Merrill Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" 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(+) base-commit: 68816ba245afc6d0e1482bde2d15b35b925b4195 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.