[Bug c/12817] New: Altivec code generation error with setjmp

[Bug c/12817] New: Altivec code generation error with setjmp

[john dot whitney at timesys dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

           Summary: Altivec code generation error with setjmp
           Product: gcc
           Version: 3.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: john dot whitney at timesys dot com
                CC: gcc-bugs at gcc dot gnu dot org,john dot whitney at
                    timesys dot com
 GCC build triplet: powerpc-linux
  GCC host triplet: i686-linux
GCC target triplet: i686-linux

We are using GCC 3.2 for the PowerPC 74xx to compile the Linux Test Project code (in specific, the 
write04 test).  I found that the resulting executable was segfaulting.  Investigation showed the 
following assembly code:

  70:   7d 80 42 a6     mfvrsave        r12
  74:   91 8c ff 20     stw     r12,-224(r12)
  78:   65 8c df ff     oris    r12,r12,57343
  7c:   61 8c ff ff     ori     r12,r12,65535
  80:   7d 80 43 a6     mtvrsave        r12

VRSAVE was 0, so line 74 resulted in a NULL pointer access.

I've come up with a much-reduced test program that exercises this problem:
-------------------
#include <signal.h>
#include <setjmp.h>
#include <limits.h>

static sigjmp_buf jmp;

int main(int argc, char **argv)
{
        char wbuf[8 * PIPE_BUF];

        if (sigsetjmp(jmp, 1)) {
                return 1;
        }
        return 0;
}
-------------------

This produces the following assembly code:

10000490 <main>:
10000490:       7c 2c 0b 78     mr      r12,r1
10000494:       3c 00 ff ff     lis     r0,-1
10000498:       60 00 7e 30     ori     r0,r0,32304
1000049c:       7c 21 01 6e     stwux   r1,r1,r0
100004a0:       38 00 fe 50     li      r0,-432
100004a4:       7e 8c 01 ce     stvx    v20,r12,r0
100004a8:       38 00 fe 60     li      r0,-416
100004ac:       7e ac 01 ce     stvx    v21,r12,r0
100004b0:       38 00 fe 70     li      r0,-400
100004b4:       7e cc 01 ce     stvx    v22,r12,r0
100004b8:       38 00 fe 80     li      r0,-384
100004bc:       7e ec 01 ce     stvx    v23,r12,r0
100004c0:       38 00 fe 90     li      r0,-368
100004c4:       7f 0c 01 ce     stvx    v24,r12,r0
100004c8:       38 00 fe a0     li      r0,-352
100004cc:       7f 2c 01 ce     stvx    v25,r12,r0
100004d0:       38 00 fe b0     li      r0,-336
100004d4:       7f 4c 01 ce     stvx    v26,r12,r0
100004d8:       38 00 fe c0     li      r0,-320
100004dc:       7f 6c 01 ce     stvx    v27,r12,r0
100004e0:       38 00 fe d0     li      r0,-304
100004e4:       7f 8c 01 ce     stvx    v28,r12,r0
100004e8:       38 00 fe e0     li      r0,-288
100004ec:       7f ac 01 ce     stvx    v29,r12,r0
100004f0:       38 00 fe f0     li      r0,-272
100004f4:       7f cc 01 ce     stvx    v30,r12,r0
100004f8:       38 00 ff 00     li      r0,-256
100004fc:       7f ec 01 ce     stvx    v31,r12,r0
10000500:       7d 80 42 a6     mfvrsave        r12
10000504:       91 8c ff 20     stw     r12,-224(r12)
10000508:       65 8c df ff     oris    r12,r12,57343
1000050c:       61 8c ff ff     ori     r12,r12,65535
10000510:       7d 80 43 a6     mtvrsave        r12
10000514:       7c 08 02 a6     mflr    r0


Again, the zero-containing r12 is used at address 0x10000500.  This appears to be caused by the 
32k stack variable, wbuf.  If that variable is made static, or reduced in size, r1 is used as expected 
in the line following mfvrsave, instead of the erroneous r12.

This problem appears in GCC 3.2, and in a test build I made of GCC 3.3.2.

[Bug c/12817] Altivec code generation error with setjmp

[john dot whitney at timesys dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817



------- Additional Comments From john dot whitney at timesys dot com  2003-10-28 20:45 -------
Created an attachment (id=5013)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5013&action=view)
Test code demonstrating problem

[Bug target/12817] Altivec code generation error with setjmp

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
  GCC build triplet|powerpc-linux               |
   GCC host triplet|i686-linux                  |
 GCC target triplet|i686-linux                  |powerpc-linux
           Keywords|                            |wrong-code


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-10-30 05:03 -------
On powerpc-apple-darwin in 3.3.2 (20030908), I get:
        mfspr r12,256
        stw r12,-224(r1)
        oris r12,r12,0xdfff
        ori r12,r12,65535
        mtspr 256,r12
which looks right.
on the mainline, GCC does not even save the altivec registers at all (why?).

[Bug target/12817] Altivec code generation error with setjmp

[segher at kernel dot crashing dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817



------- Additional Comments From segher at kernel dot crashing dot org  2003-10-30 13:44 -------
Subject: Re:  Altivec code generation error with setjmp

pinskia at gcc dot gnu dot org wrote:
> On powerpc-apple-darwin in 3.3.2 (20030908), I get:
>         mfspr r12,256
>         stw r12,-224(r1)
>         oris r12,r12,0xdfff
>         ori r12,r12,65535
>         mtspr 256,r12
> which looks right.

It does.

> on the mainline, GCC does not even save the altivec registers at all (why?).

Why should it save _any_ registers (that are not changed before the call
to setjmp()?  setjmp() will just save them again?

[Bug target/12817] Altivec code generation error with setjmp

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-11-18 07:28 -------
Confirmed, I do not know why gcc saves them at all, note that on the mainline now gcc saves the 
altivec registers but right.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |pessimizes-code
   Last reconfirmed|0000-00-00 00:00:00         |2003-11-18 07:28:48
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] Altivec code generation error with setjmp

[wilson at gcc dot gnu dot org]

------- Additional Comments From wilson at gcc dot gnu dot org  2003-11-21 06:29 -------
Gcc no longer saves the FP or altivec registers.  See PR 13133 and the patch I
checked in for it in the message
    http://gcc.gnu.org/ml/gcc-patches/2003-11/msg01667.html

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] Altivec code generation error with setjmp

[segher at kernel dot crashing dot org]

------- Additional Comments From segher at kernel dot crashing dot org  2003-11-21 09:23 -------
I don't think the actual bug of this report is solved.

Hard to check without a testcase, though ;-)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] Altivec code generation error with setjmp

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-11-21 09:49 -------
Can still happen when you use all the altivec registers, segher is working on a fix for that 
bug and this is really a target bug.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
           Keywords|pessimizes-code             |
         Resolution|FIXED                       |
   Target Milestone|---                         |3.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |NEW
            Summary|Altivec code generation     |[SYSV] Altivec code
                   |error with setjmp           |generation error with many
                   |                            |registers used


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |segher at kernel dot
                   |                            |crashing dot org
   Target Milestone|3.4.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[amodra at bigpond dot net dot au]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |amodra at bigpond dot net
                   |dot org                     |dot au
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[amodra at bigpond dot net dot au]

------- Additional Comments From amodra at bigpond dot net dot au  2004-11-26 09:54 -------
/* vrsave code in the prologue trashes frame pointer reg
   -m32 -maltivec -mabi=altivec -mvrsave=yes -S pr12817.c */

#define vector __attribute__ ((vector_size (16)))

extern void foo (int *);

vector int
v_add (vector int a, vector int b)
{
  int x[10000];
  foo (x);
  return a + b;
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[amodra at bigpond dot net dot au]

------- Additional Comments From amodra at bigpond dot net dot au  2004-11-26 10:53 -------
http://gcc.gnu.org/ml/gcc-patches/2004-11/msg02247.html

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-12-01 05:48 -------
Subject: Bug 12817

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	amodra@gcc.gnu.org	2004-12-01 05:47:52

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

Log message:
	PR target/12817
	* config/rs6000/rs6000.c (rs6000_emit_prologue): Use r0 for vrsave.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.6657&r2=2.6658
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/rs6000/rs6000.c.diff?cvsroot=gcc&r1=1.758&r2=1.759



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-12-01 05:54 -------
Subject: Bug 12817

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_4-branch
Changes by:	amodra@gcc.gnu.org	2004-12-01 05:54:22

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

Log message:
	PR target/12817
	* config/rs6000/rs6000.c (rs6000_emit_prologue): Use r0 for vrsave.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=2.2326.2.710&r2=2.2326.2.711
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/rs6000/rs6000.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.576.2.36&r2=1.576.2.37



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-12-01 06:13 -------
Subject: Bug 12817

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_3-branch
Changes by:	amodra@gcc.gnu.org	2004-12-01 06:13:19

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

Log message:
	PR target/12817
	* config/rs6000/rs6000.c (rs6000_emit_prologue): Use r0 for vrsave.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.16114.2.1029&r2=1.16114.2.1030
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/rs6000/rs6000.c.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.403.2.15&r2=1.403.2.16



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[amodra at bigpond dot net dot au]

------- Additional Comments From amodra at bigpond dot net dot au  2004-12-01 06:21 -------
Fixed on all active branches.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817

[Bug target/12817] [SYSV] Altivec code generation error with many registers used

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |3.4.4 3.3.6 4.0.0
   Target Milestone|---                         |3.3.6


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12817