From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id BDCCA3857805; Thu, 30 Dec 2021 13:36:14 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BDCCA3857805 From: "cvs-commit at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug debug/103808] [12 Regression] '-fcompare-debug' failure (length) w/ -O2 -ftrapv since r12-5944-ga7acb6dca941db2b Date: Thu, 30 Dec 2021 13:36:14 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: debug X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: ice-on-valid-code, wrong-debug X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 12.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Dec 2021 13:36:14 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103808 --- Comment #6 from CVS Commits --- The master branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:52441f18db7e051c16f2e6e12f415b93cb5450c4 commit r12-6153-g52441f18db7e051c16f2e6e12f415b93cb5450c4 Author: Jakub Jelinek Date: Thu Dec 30 14:35:06 2021 +0100 emit-rtl: Fix a -fcompare-debug issue due to var-tracking [PR103808] We get a -fcompare-debug FAIL on the following testcase. The problem is that during cprop we get when a TImode pseudo holding x is being constructed: (debug_insn 111 59 103 7 (var_location:TI D#2 (clobber (const_int 0 [0]= ))) -1 (nil)) (insn 103 111 110 7 (clobber (reg/v:TI 89 [ x ])) "pr103808.c":8:9 -1 (nil)) (debug_insn 110 103 104 7 (var_location:TI D#2 (subreg:TI (reg:DI 111 [= x ]) 0)) -1 (nil)) (insn 104 110 109 7 (set (subreg:DI (reg/v:TI 89 [ x ]) 0) (reg:DI 111 [ x ])) "pr103808.c":8:9 80 {*movdi_internal} (expr_list:REG_DEAD (reg:DI 111 [ x ]) (nil))) Now, during RA that paradoxical subreg in a debug insn obviously can't affect where pseudo 111 is allocated and RA puts it into the bp registe= r, so we have: (debug_insn 110 111 109 4 (var_location:TI D#2 (reg:TI 6 bp [orig:111 x= ] [111])) -1 (nil)) Now, during var-tracking when we for: (debug_insn 25 23 26 3 (var_location:TI x (concatn/v:TI [ (reg:DI 6 bp [orig:111 x ] [111]) (subreg:DI (debug_expr:TI D#2) 8) ])) "pr103808.c":8:9 -1 (nil)) try to simplify the highpart subreg of bp, gen_rtx_REG_offset is called= in: if (HARD_REGISTER_NUM_P (final_regno)) { rtx x =3D gen_rtx_REG_offset (op, outermode, final_regno, subreg_memory_offset (outermode, innermode, byte)); and that unfortunately sets REG_ATTRS on stack_pointer_rtx, because gen_rtx_REG_offset uses gen_rtx_REG which for Pmode STACK_POINTER_REGNUM returns stack_pointer_rtx rather than newly created register. The clobbering of REG_ATTRS on the shared stack_pointer_rtx then shows = up in the dumps as (reg/f:DI 7 sp [ x+8 ]) instead of (reg/f:DI 7 sp) that shows up without var-tracking. Clobbering of REG_ATTRS on the shared *_pointer_rtx looks just wrong. So, IMHO either simplify_gen_subreg -> gen_rtx_REG_offset should call gen_raw_REG to make sure we get a new non-shared REG we can set REG_ATT= RS on, or we should make sure that we don't overwrite the REG_ATTRS on the shared REGs (but then simplify_gen_subreg shouldn't try to overwrite ORIGINAL_REGNO on those either). For non-DEBUG_INSNs, I'd hope this never happens, the RA shouldn't allo= cate multi-word regs overlapping with stack pointer, hard frame pointer etc. 2021-12-30 Jakub Jelinek PR debug/103808 * emit-rtl.c (gen_rtx_REG_offset): Use gen_raw_REG instead of gen_rtx_REG. * gcc.dg/pr103808.c: New test.=