[Bug c/25572] New: ppc64 -mminimal-toc trashes r30

[Bug c/25572] New: ppc64 -mminimal-toc trashes r30

[anton at samba dot org]

We found this problem when building a ppc64 Linux kernel. It turns out r30 was
not preserved in a function that was using a local TOC. The compiler used was:

gcc version 4.0.3 20051201 (prerelease) (Debian 4.0.2-5)

Although it seems to reproduce on older toolchains too (eg 3.4).

pinskia cut the original test case down to:

/* Compile with -m64 -O2 -mminimal-toc */
int per_cpu__kstat;

int *f()
{
  int *__ptr;
  asm volatile(";%0":"=g"(__ptr):"0"(&per_cpu__kstat));
  return __ptr;
}

/*
.f:
        ld 30,.LCTOC0@toc(2)
        ld 9,.LC0-.LCTOC1(30)
        mr 3,9
#APP
        ;3
#NO_APP

*/


-- 
           Summary: ppc64 -mminimal-toc trashes r30
           Product: gcc
           Version: 4.0.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: anton at samba dot org
GCC target triplet: powerpc64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2005-12-27 00:18 -------
Confirmed, not a regression.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|c                           |target
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
      Known to fail|                            |3.3.3 4.0.0 3.4.0 4.1.0
                   |                            |4.2.0
   Last reconfirmed|0000-00-00 00:00:00         |2005-12-27 00:18:30
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at bigpond dot net dot au]

------- Comment #2 from amodra at bigpond dot net dot au  2005-12-28 03:03 -------
Happens at -O0 too.  At -O0, r30 is used for the first time when reload decides
that the asm_operands in the following needs reloading.  regs_ever_live[30]
isn't set.

(insn 8 6 10 3 (set (mem/c/i:DI (plus:DI (reg/f:DI 113 sfp)
                (const_int 48 [0x30])) [0 __ptr+0 S8 A128])
        (asm_operands/v:DI (";%0") ("=g") 0 [
                (symbol_ref:DI ("per_cpu__kstat") <var_decl 0x80003499a0
per_cpu__kstat>)
            ]
             [
                (asm_input:DI ("0"))
            ] ("/src/tmp/pr25572.c") 7)) -1 (nil)
    (nil))


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at bigpond dot net dot au]

------- Comment #3 from amodra at bigpond dot net dot au  2005-12-28 04:52 -------
Adding
  if (no_new_pseudos)
    regs_ever_live[TOC_REGISTER] = 1;
to rs6000.c:create_TOC_reference fixes this problem.  There seems to be
precedent for such chicanery: eg. rs6000_got_register and a number of places in
i386.c setting regs_ever_live[PIC_OFFSET_TABLE_REGNUM].


-- 

amodra at bigpond dot net dot au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dje at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at bigpond dot net dot au]

-- 

amodra at bigpond dot net dot au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |amodra at bigpond dot net
                   |dot org                     |dot au
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-12-27 00:18:30         |2005-12-28 05:18:48
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at gcc dot gnu dot org]

------- Comment #4 from amodra at gcc dot gnu dot org  2005-12-29 01:10 -------
Subject: Bug 25572

Author: amodra
Date: Thu Dec 29 01:10:05 2005
New Revision: 109133

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=109133
Log:
        PR target/25572
        * config/rs6000/rs6000.c (create_TOC_reference): Set regs_ever_live.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/rs6000/rs6000.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at gcc dot gnu dot org]

------- Comment #5 from amodra at gcc dot gnu dot org  2005-12-29 01:14 -------
Subject: Bug 25572

Author: amodra
Date: Thu Dec 29 01:14:18 2005
New Revision: 109134

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=109134
Log:
        PR target/25572
        * config/rs6000/rs6000.c (create_TOC_reference): Set regs_ever_live.


Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/config/rs6000/rs6000.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at gcc dot gnu dot org]

------- Comment #6 from amodra at gcc dot gnu dot org  2005-12-29 01:20 -------
Subject: Bug 25572

Author: amodra
Date: Thu Dec 29 01:20:15 2005
New Revision: 109135

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=109135
Log:
        PR target/25572
        * config/rs6000/rs6000.c (create_TOC_reference): Set regs_ever_live.


Modified:
    branches/gcc-4_0-branch/gcc/ChangeLog
    branches/gcc-4_0-branch/gcc/config/rs6000/rs6000.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at gcc dot gnu dot org]

------- Comment #7 from amodra at gcc dot gnu dot org  2005-12-29 01:29 -------
Subject: Bug 25572

Author: amodra
Date: Thu Dec 29 01:29:18 2005
New Revision: 109136

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=109136
Log:
        PR target/25572
        * config/rs6000/rs6000.c (create_TOC_reference): Set regs_ever_live.


Modified:
    branches/gcc-3_4-branch/gcc/ChangeLog
    branches/gcc-3_4-branch/gcc/config/rs6000/rs6000.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[amodra at bigpond dot net dot au]

------- Comment #8 from amodra at bigpond dot net dot au  2005-12-29 01:29 -------
Fixed


-- 

amodra at bigpond dot net dot au changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572

[Bug target/25572] ppc64 -mminimal-toc trashes r30

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|3.3.3 4.0.0 3.4.0 4.1.0     |3.3.3 4.0.0 3.4.0
                   |4.2.0                       |
      Known to work|                            |4.0.3 3.4.6 4.1.0 4.2.0
   Target Milestone|---                         |3.4.6


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572