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t=1715706884; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=esz8d4WGCVVmDALehWpmG27uSpiF1W7Gc0DXy06e4ls=; b=1+Kw2elXqaHyGdRJK1t9Zb3wUOX5axdyD9hm1I99V69pdP7I2TvgFKCem7CoxWzYSuvwo1 Am/JQP2tnPX+XLDA== Date: Tue, 14 May 2024 19:14:44 +0200 (CEST) From: Richard Biener To: Qing Zhao cc: kees Cook , "gcc-patches@gcc.gnu.org" , "pinskia@gmail.com" , "dmalcolm@redhat.com" Subject: Re: [RFC][PATCH] PR tree-optimization/109071 - -Warray-bounds false positive warnings due to code duplication from jump threading In-Reply-To: <5B108F20-411B-452B-91FF-DA5A727EC866@oracle.com> Message-ID: References: <20240513194830.1676938-1-qing.zhao@oracle.com> <35799652-55op-79os-ro61-56094939s0o2@fhfr.qr> <6BB88011-F888-4949-A65D-FDB351128B0F@oracle.com> <5s7oqqq0-4037-22qr-7no5-nonrq3qsp32r@fhfr.qr> <5B108F20-411B-452B-91FF-DA5A727EC866@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.996]; MIME_GOOD(-0.10)[text/plain]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[]; TO_DN_EQ_ADDR_SOME(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_ZERO(0.00)[0]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[chromium.org,gcc.gnu.org,gmail.com,redhat.com]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email] X-Spam-Score: -4.30 X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Tue, 14 May 2024, Qing Zhao wrote: > > > > On May 14, 2024, at 10:29, Richard Biener wrote: > > [...] > > It would of course > > need experimenting since we can end up moving stmts and merging blocks > > though the linear traces created by jump threading should be quite > > stable (as opposed to say the unrolling case where multiple instances > > of the loop body likely will end up in the exact same basic block). > > Do you mean, for loop unrolling the approach with one extra stmt for one > basic block might be even harder and unreliable? The question is whether the stmt marks the whole block or whether we for example add both a START and END stmt covering a copied path. I would guess for unrolling we need definitely need to do the latter (so we can diagnose "on the 3rd iteration of an unrolled loop" or similar). Richard.