From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4112 invoked by alias); 10 Mar 2011 11:03:02 -0000 Received: (qmail 4068 invoked by uid 22791); 10 Mar 2011 11:03:01 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 10 Mar 2011 11:02:54 +0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/48031] [4.4/4.5 Regression] gcc.c-torture/compile/pr42956.c ICEs gcc on m68k-linux, ivopts related? X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Keywords: ice-on-valid-code X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.4.6 X-Bugzilla-Changed-Fields: Status Last reconfirmed CC AssignedTo Ever Confirmed Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Thu, 10 Mar 2011 11:03:00 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2011-03/txt/msg00982.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48031 Richard Guenther changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2011.03.10 11:02:33 CC| |ebotcazou at gcc dot | |gnu.org AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org |gnu.org | Ever Confirmed|0 |1 --- Comment #7 from Richard Guenther 2011-03-10 11:02:33 UTC --- First of all, confirmed with a cross. The issue seems to be with variable-length arrays: D.2079_96 = D.2025 /[ex] 2; D.2080_21 = &(*D.2050_128)[0]{lb: 0 sz: D.2079_96 * 2}.err; What happens is that we have an induction variable base of the form (unsigned int) &((struct Result *) D.2050_128)->err and end up folding the conversion to an array reference during gimplifying it here /* *(foo *)fooarrptr => (*fooarrptr)[0] */ if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE && type == TREE_TYPE (TREE_TYPE (subtype))) { tree type_domain; tree min_val = size_zero_node; sub = build_fold_indirect_ref_loc (loc, sub); type_domain = TYPE_DOMAIN (TREE_TYPE (sub)); if (type_domain && TYPE_MIN_VALUE (type_domain)) min_val = TYPE_MIN_VALUE (type_domain); return build4_loc (loc, ARRAY_REF, type, sub, min_val, NULL_TREE, NULL_TREE); } and then add a lower bound and step element in gimplify_compound_lval: if (!TREE_OPERAND (t, 3)) { tree elmt_type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 0))); tree elmt_size = unshare_expr (array_ref_element_size (t)); tree factor = size_int (TYPE_ALIGN_UNIT (elmt_type)); /* Divide the element size by the alignment of the element type (above). */ elmt_size = size_binop_loc (loc, EXACT_DIV_EXPR, elmt_size, factor); if (!is_gimple_min_invariant (elmt_size)) { TREE_OPERAND (t, 3) = elmt_size; tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, is_gimple_reg, fb_rvalue); ret = MIN (ret, tret); } } A fix would be for example avoiding the folding for variable-sized element types. Another one would be to avoid putting in a operand 3 into the array-ref when the index is equal to the lower bound (but I'm not sure if that works, if the index is zero would probably work, but then a variant of the code might still ICE the same way). It's mixing VLA unaware foldings into the mids of GIMPLE which is the root of the issue though. The issue is latent on trunk. Patch for the first (and safe) idea: Index: gcc/fold-const.c =================================================================== --- gcc/fold-const.c (revision 170818) +++ gcc/fold-const.c (working copy) @@ -15554,7 +15560,8 @@ fold_indirect_ref_1 (location_t loc, tre } /* *(foo *)&fooarray => fooarray[0] */ else if (TREE_CODE (optype) == ARRAY_TYPE - && type == TREE_TYPE (optype)) + && type == TREE_TYPE (optype) + && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST) { tree type_domain = TYPE_DOMAIN (optype); tree min_val = size_zero_node; @@ -15633,7 +15640,8 @@ fold_indirect_ref_1 (location_t loc, tre /* *(foo *)fooarrptr => (*fooarrptr)[0] */ if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE - && type == TREE_TYPE (TREE_TYPE (subtype))) + && type == TREE_TYPE (TREE_TYPE (subtype)) + && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST) { tree type_domain; tree min_val = size_zero_node; Eric, can you see any issues with that and Ada?