From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by sourceware.org (Postfix) with ESMTPS id F13A33858D33 for ; Thu, 16 Feb 2023 08:47:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org F13A33858D33 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id B84ED1F8B5; Thu, 16 Feb 2023 08:47:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1676537260; 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=nk5IKt4QY1jvuCzGuY4WwZFgHYBhyokAEQ50D4j1wIc=; b=vF81pUK1Qn9xWJwp9dvT1tV3hZEnHBuGaEBx9q6QQKFoRYHFL59Cg8h1TkvWFF9jIE1Fh8 j5VlBZLo++bsPITHsyjX30vwmHSxsb4OCHp9qfXtVoc0ha23mWZjL8eEL2cu0V3DDXpm3P kVJsZ/FcGWMEaCKbFqT8v1v7k3xctBg= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1676537260; 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=nk5IKt4QY1jvuCzGuY4WwZFgHYBhyokAEQ50D4j1wIc=; b=IRLndzsDjP6jJnqOOmYUwlgEUmJLaF5CgyqBkO4N6yBa6759/Gxqt1taIJ06KTg3XGGisp XhjvNMD1QH2vNXBA== Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 91AB32C141; Thu, 16 Feb 2023 08:47:40 +0000 (UTC) Date: Thu, 16 Feb 2023 08:47:40 +0000 (UTC) From: Richard Biener To: Jakub Jelinek cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH] reassoc: Fix up (ab) handling in eliminate_redundant_comparison [PR108783] In-Reply-To: Message-ID: References: User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-5.1 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 Thu, 16 Feb 2023, Jakub Jelinek wrote: > Hi! > > The following testcase ICEs because eliminate_redundant_comparison sees > redundant comparisons in &&/|| where the comparison has (ab) SSA_NAME, > maybe_fold_{and,or}_comparisons optimizes them into a single comparison > and build_and_add_sum emits a new comparison close to the definition > operands, which in this case is before a returns_twice call (which is > invalid). Generally reassoc just punts on (ab) SSA_NAMEs, declares them > non-reassociable etc., so the second half of this patch does that. > > Though we can do better in this case; the function has special code > when maybe_fold_{and,or}_comparisons returns INTEGER_CST (false/true) > or when what it returns is the same as curr->op (the first of the > comparisons we are considering) - in that case we just remove the > second one and keep the first one. The reason it doesn't match is that > curr->op is a SSA_NAME whose SSA_NAME_DEF_STMT is checked to be a > comparison, in this case _42 = a_1(ab) != 0 and the other comparison > is also like that. maybe_fold_{and,or}_comparisons looks through the > definitions though and so returns a_1(ab) != 0 as tree. > So the first part of the patch checks whether that returned comparison > isn't the same as the curr->op comparison and if yes, it just overrides > t back to curr->op so that its SSA_NAME is reused. In that case we can > handle even (ab) in {,new}op{1,2} because we don't create a new comparison > of that, just keep using the existing one. And t can't be (ab) because > otherwise it wouldn't be considered a reassociable operand. > > The (ab) checks are needed say when we have a_1(ab) == 42 || a_1(ab) > 42 > kind of comparisons where maybe_fold_{and,or}_comparisons returns a new > comparison not existing in the IL yet. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? OK. Thanks, Richard. > 2023-02-15 Jakub Jelinek > > PR tree-optimization/108783 > * tree-ssa-reassoc.cc (eliminate_redundant_comparison): If lcode > is equal to TREE_CODE (t), op1 to newop1 and op2 to newop2, set > t to curr->op. Otherwise, punt if either newop1 or newop2 are > SSA_NAME_OCCURS_IN_ABNORMAL_PHI SSA_NAMEs. > > * gcc.c-torture/compile/pr108783.c: New test. > > --- gcc/tree-ssa-reassoc.cc.jj 2023-01-12 21:04:08.726238049 +0100 > +++ gcc/tree-ssa-reassoc.cc 2023-02-15 13:28:04.987278895 +0100 > @@ -2272,6 +2272,15 @@ eliminate_redundant_comparison (enum tre > STRIP_USELESS_TYPE_CONVERSION (newop2); > if (!is_gimple_val (newop1) || !is_gimple_val (newop2)) > continue; > + if (lcode == TREE_CODE (t) > + && operand_equal_p (op1, newop1, 0) > + && operand_equal_p (op2, newop2, 0)) > + t = curr->op; > + else if ((TREE_CODE (newop1) == SSA_NAME > + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (newop1)) > + || (TREE_CODE (newop2) == SSA_NAME > + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (newop2))) > + continue; > } > > if (dump_file && (dump_flags & TDF_DETAILS)) > --- gcc/testsuite/gcc.c-torture/compile/pr108783.c.jj 2023-02-15 12:42:46.244340524 +0100 > +++ gcc/testsuite/gcc.c-torture/compile/pr108783.c 2023-02-15 13:24:47.515187118 +0100 > @@ -0,0 +1,42 @@ > +/* PR tree-optimization/108783 */ > + > +__attribute__((returns_twice)) int baz (int, int); > + > +int > +bar (int x) > +{ > + return x; > +} > + > +int > +foo (int x, int y) > +{ > + int a; > + > + a = bar (x); > + baz (x, y); > + > + return y && a && a; > +} > + > +int > +qux (int x, int y) > +{ > + int a; > + > + a = bar (x); > + baz (x, y); > + > + return y && a != 42 && a >= 42; > +} > + > +int > +corge (int x, int y) > +{ > + int a; > + > + a = bar (x); > + baz (x, y); > + > + return y || a == 42 || a > 42; > +} > > Jakub > > -- Richard Biener SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg, Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman; HRB 36809 (AG Nuernberg)