From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-446634-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 8674 invoked by alias); 18 Mar 2014 01:11:05 -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 8617 invoked by uid 48); 18 Mar 2014 01:11:00 -0000
From: "uwe at netbsd dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/60039] sh3 optimisation bug with -O2
Date: Tue, 18 Mar 2014 01:11:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 4.8.3
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: uwe at netbsd dot 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-60039-4-TI5Or9SpUW@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-60039-4@http.gcc.gnu.org/bugzilla/>
References: <bug-60039-4@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: 2014-03/txt/msg01503.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60039

--- Comment #6 from Valeriy E. Ushakov <uwe at netbsd dot org> ---
As far as I can tell the actual problem is in this code:

    .loc 1 189 0
    mov.l    .L91,r0
    ; ...
    add    r12,r0
    mov.l    .L84,r1
    jsr    @r0    ; udivsi3 for 32*1024/pagesz
     ; ...
    .loc 1 189 0
    bsrf    r1    ; morepages call
.LPCS6:
     mov    r0,r4    ; with result of division

.L91:
    .long    __udivsi3@GOTOFF
.L84:
    .long    morepages-(.LPCS6+2)

That code assumes that r1 is not clobbered, but in our case it is.
So instead of calling morepages() we end up with a small branch forward.
and pagepool_start is not initialized properly, causing SIGSEGV later.

I don't remember how we build udivsi3 &c bits in NetBSD, we might be
violating assumptions about clobbered regs.

FWIW, our in-tree gcc 4.5 generates for this:

        mov.l   .L75,r0
    ; ...
        mov.l   @(r0,r12),r2
        jsr     @r2
         ; ...
        mov.l   .L67,r1
        mov     r0,r4
        bsrf    r1
.LPCS6:

.L75:
        .long   __udivsi3_i4i@GOT
.L67:
        .long   morepages-(.LPCS6+2)

Because, as far as I can tell, in 4.5 sh_override_options() has an extra

    else if (TARGET_SH2)    /* ??? EXPERIMENTAL */
      sh_div_strategy = SH_DIV_CALL_TABLE;

clause, that is missing in 4.8 sh_option_override().