From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-380126-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 24694 invoked by alias); 16 Jan 2012 16:16:58 -0000
Received: (qmail 24686 invoked by uid 22791); 16 Jan 2012 16:16:57 -0000
X-SWARE-Spam-Status: No, hits=-2.9 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; Mon, 16 Jan 2012 16:16:44 +0000
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug bootstrap/51872] New: [4.7 Regression] Shrink-wrapping with -mminimal-toc causes bootstrap failure
Date: Mon, 16 Jan 2012 16:25:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: bootstrap
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub 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-Changed-Fields:
Message-ID: <bug-51872-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
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
X-SW-Source: 2012-01/txt/msg01801.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51872

             Bug #: 51872
           Summary: [4.7 Regression] Shrink-wrapping with -mminimal-toc
                    causes bootstrap failure
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jakub@gcc.gnu.org
                CC: amodra@gcc.gnu.org, bernds@gcc.gnu.org,
                    dje@gcc.gnu.org
            Target: powerpc64-linux


powerpc64-linux doesn't bootstrap with -mminimal-toc in CFLAGS/CXXFLAGS, due to
shrink-wrapping, as crtbegin.o is miscompiled.

Short testcase for -m64 -O2 -mminimal-toc:
static void *var[] __attribute__ ((used, section("jlist"),
aligned(sizeof(void*)))) = { };
extern void bar (void *) __attribute__ ((weak));

static void __attribute__((noinline, noclone))
baz (void)
{
  asm volatile ("" : : : "memory");
}

void
foo (void)
{
  if (var[0])
    {
      void (*register_classes) (void *) = bar;
      __asm ("" : "+r" (register_classes));
      if (register_classes)
       register_classes (var);
    }
  baz ();
}

The problem is that the TOC register (r30) isn't added to the
set_up_by_prologue
regset (flag_pic is 0, TARGET_MINIMAL_TOC is true and the prologue computes the
TOC_REGISTER).  I wonder if we don't need a target hook that will add
additional registers to set_up_by_prologue regset.