From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2a07:de40:b251:101:10:150:64:2]) by sourceware.org (Postfix) with ESMTPS id EB6473858C3A for ; Mon, 26 Feb 2024 14:29:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org EB6473858C3A Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de ARC-Filter: OpenARC Filter v1.0.0 sourceware.org EB6473858C3A Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2a07:de40:b251:101:10:150:64:2 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708957776; cv=none; b=DvCGWdksd1PPMpY6Gli47QteLrJOuiz6hQqfvVomYd+MFSx0cHP1s5uKs0wPjHrqkoEmstt/IuCqk5BGC5sM1UlqN3MMnumRyDur6B3GJggA4Im1gbMv3J5ptdovVB0KI2M3g5u7PBxWbcqZVuhTe4fz4bOuavMqgQEZvPnQjKE= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708957776; c=relaxed/simple; bh=4WZ4uBEsdi3cuXyiMsTYrChAx4k3sNpMnVkf03u0hzM=; h=DKIM-Signature:DKIM-Signature:DKIM-Signature:DKIM-Signature:Date: From:To:Subject:Message-ID:MIME-Version; b=Y8WbUfsJWYJ68AR1HO26nKoHAEsPaj12IjaN3hc0UT7XnAVmbpBFq2Gxv+zD+t1UfLzdo6QPuqT5h/RJuDDPmP5qNa0wecoofYBcVAb1SIdVcY9OC9+6KKnw6VZqBOVFYMCPH2VOXQ4UMThvFQQfv6cK87QBx4YE2+SwVUAeYI8= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from [10.168.4.150] (unknown [10.168.4.150]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 96E1D1FB4B; Mon, 26 Feb 2024 14:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1708957770; 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=+sG74TYGPkr5nYypDZ14+4CruGUUEDVyzgzrgyOv51I=; b=pROl+mBv18Fs1vdrd5pGqtw0maa4t7tk3rlpXMJGezmia5aCTSkZkl9pEdBlATh6r9O3y2 RFaWbQnK4p/La/vgRRwm7USFue8yFSGRQJFzQ++4X/rB0tc5zaQcBb/5gPVLKieY/yS6dN 3KQhWUsyNAgA/GJpqcCqtN9vcFW5U1Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1708957770; 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=+sG74TYGPkr5nYypDZ14+4CruGUUEDVyzgzrgyOv51I=; b=wloav+PlWdFXBHSLzHAs48JtztmrNbNXnv71lkVuQiAg9yYSpNbcpA9un0LLLG4DhOWmbf aU9xbqtS5wlEAiBw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1708957770; 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=+sG74TYGPkr5nYypDZ14+4CruGUUEDVyzgzrgyOv51I=; b=pROl+mBv18Fs1vdrd5pGqtw0maa4t7tk3rlpXMJGezmia5aCTSkZkl9pEdBlATh6r9O3y2 RFaWbQnK4p/La/vgRRwm7USFue8yFSGRQJFzQ++4X/rB0tc5zaQcBb/5gPVLKieY/yS6dN 3KQhWUsyNAgA/GJpqcCqtN9vcFW5U1Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1708957770; 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=+sG74TYGPkr5nYypDZ14+4CruGUUEDVyzgzrgyOv51I=; b=wloav+PlWdFXBHSLzHAs48JtztmrNbNXnv71lkVuQiAg9yYSpNbcpA9un0LLLG4DhOWmbf aU9xbqtS5wlEAiBw== Date: Mon, 26 Feb 2024 15:29:30 +0100 (CET) From: Richard Biener To: Jakub Jelinek cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH] tree-optimization/114074 - CHREC multiplication and undefined overflow In-Reply-To: Message-ID: References: <83476.124022609150401789@us-mta-131.us.mimecast.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Authentication-Results: smtp-out2.suse.de; none X-Spam-Score: 1.62 X-Spamd-Result: default: False [1.62 / 50.00]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; NEURAL_SPAM_SHORT(2.73)[0.908]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_ZERO(0.00)[0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; BAYES_HAM(-0.00)[35.93%] X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS,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 List-Id: On Mon, 26 Feb 2024, Jakub Jelinek wrote: > On Mon, Feb 26, 2024 at 03:15:02PM +0100, Richard Biener wrote: > > When folding a multiply CHRECs are handled like {a, +, b} * c > > is {a*c, +, b*c} but that isn't generally correct when overflow > > invokes undefined behavior. The following uses unsigned arithmetic > > unless either a is zero or a and b have the same sign. > > > > I've used simple early outs for INTEGER_CSTs and otherwise use > > a range-query since we lack a tree_expr_nonpositive_p. > > What about testing > (get_range_pos_neg (CHREC_LEFT (op0)) > | get_range_pos_neg (CHREC_RIGHT (op0))) != 3 > ? Ah, didn't know about that. It seems to treat zero as "always positive", so for 0 and -1 I'd get 3. OK as I check for zero CHREC_LEFT separately. I'll note that get_range_pos_neg only asks global range query and for SSA names (but not sure if range_of_expr handles aribitrary GENERIC as SCEV tends to have here ...). Will update the patch, I think any improvement should be done to get_range_pos_neg (it's a bit odd in behavior for unsigned but I have only signed things incoming). Richard.