From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-456462-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 21763 invoked by alias); 16 Jul 2014 08:29:31 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 21696 invoked by uid 48); 16 Jul 2014 08:29:27 -0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/61801] sched2 miscompiles syscall sequence with -g
Date: Wed, 16 Jul 2014 08:29:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 4.8.3
X-Bugzilla-Keywords: missed-optimization, ra, wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields:
Message-ID: <bug-61801-4-AvRSw4f1Q9@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-61801-4@http.gcc.gnu.org/bugzilla/>
References: <bug-61801-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2014-07/txt/msg01053.txt.bz2

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's combine combining 120 into 123 and on the way via propagate_for_debug
replacing reg:SI 126 with the asm in the debug_insn.

(insn 120 119 122 15 (parallel [
            (set (reg:SI 126 [ resultvar ])
                (asm_operands/v:SI ("xchgl %%ebx, %%edi
        int $0x80
        xchgl %%edi, %%ebx
...
(debug_insn 122 120 123 15 (var_location:SI resultvar (reg:SI 126 [ resultvar
])) bug-887141_pthread_create.1.min.i:77 -1
     (nil))
(insn 123 122 124 15 (set (reg/v:SI 84 [ result ])
        (reg:SI 126 [ resultvar ])) bug-887141_pthread_create.1.min.i:77 90
{*movsi_internal}
     (expr_list:REG_DEAD (reg:SI 126 [ resultvar ])
        (nil)))

So to avoid generating debug-insns with asm_operands loc maybe do

Index: valtrack.c
===================================================================
--- valtrack.c  (revision 212580)
+++ valtrack.c  (working copy)
@@ -197,6 +197,12 @@ propagate_for_debug (rtx insn, rtx last,
       next = NEXT_INSN (insn);
       if (DEBUG_INSN_P (insn))
        {
+         if (GET_CODE (src) == ASM_OPERANDS)
+           {
+             INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
+             df_insn_rescan (insn);
+             continue;
+           }
          loc = simplify_replace_fn_rtx (INSN_VAR_LOCATION_LOC (insn),
                                         dest, propagate_for_debug_subst, &p);
          if (loc == INSN_VAR_LOCATION_LOC (insn))

which "fixes" the bug.