[Bug c/26643] New: Linux matroxfb_probe miscompiled

[Bug c/26643] New: Linux matroxfb_probe miscompiled

[olh at suse dot de]

This testcase does not return 0 on powerpc64-suse-linux and s390x-suse-linux
with compiled with -O1
but it does with -O0.
I tried all the new opts from -O0 to -O1, but adding them all to -O0 does not
fix it. No idea why.

flags='  -O1'
gcc -Wall -c -o /tmp/main.o /tmp/main.c $flags
gcc -Wall -c -o /tmp/matroxfb_probe.o /tmp/matroxfb_probe.c $flags
gcc -Wall -o /tmp/matroxfb_probe  /tmp/main.o /tmp/matroxfb_probe.o $flags
/tmp/matroxfb_probe


-- 
           Summary: Linux matroxfb_probe miscompiled
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: olh at suse dot de
 GCC build triplet: powerpc64-linux
  GCC host triplet: powerpc64-linux
GCC target triplet: powerpc64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug c/26643] Linux matroxfb_probe miscompiled

[olh at suse dot de]

------- Comment #1 from olh at suse dot de  2006-03-11 14:25 -------
Created an attachment (id=11021)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11021&action=view)
/tmp/main.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug c/26643] Linux matroxfb_probe miscompiled

[olh at suse dot de]

------- Comment #2 from olh at suse dot de  2006-03-11 14:25 -------
Created an attachment (id=11022)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11022&action=view)
/tmp/matroxfb_probe.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug c/26643] Linux matroxfb_probe miscompiled

[olh at suse dot de]

------- Comment #3 from olh at suse dot de  2006-03-11 14:30 -------
generated asm is:

00000000100006d0 <.matroxfb_probe>:
    100006d0:   7c 08 02 a6     mflr    r0
    100006d4:   fb e1 ff f8     std     r31,-8(r1)
    100006d8:   7c 7f 1b 78     mr      r31,r3
    100006dc:   38 a0 00 08     li      r5,8
    100006e0:   f8 01 00 10     std     r0,16(r1)
    100006e4:   f8 21 ff 71     stdu    r1,-144(r1)
    100006e8:   60 00 00 00     nop
    100006ec:   e8 63 00 20     ld      r3,32(r3)
    100006f0:   80 9f 00 40     lwz     r4,64(r31)
    100006f4:   38 c1 00 70     addi    r6,r1,112
    100006f8:   4b ff ff 49     bl      10000640 <.pci_bus_read_config_byte>
    100006fc:   60 00 00 00     nop
    10000700:   e9 22 80 58     ld      r9,-32680(r2)
    10000704:   a0 09 00 00     lhz     r0,0(r9)
    10000708:   2f 80 00 00     cmpwi   cr7,r0,0
    1000070c:   41 9e 00 54     beq-    cr7,10000760 <.matroxfb_probe+0x90>
    10000710:   80 7f 00 44     lwz     r3,68(r31)
    10000714:   89 61 00 70     lbz     r11,112(r1)
    10000718:   48 00 00 18     b       10000730 <.matroxfb_probe+0x60>
    1000071c:   60 00 00 00     nop
    10000720:   39 29 00 28     addi    r9,r9,40
    10000724:   a0 09 00 00     lhz     r0,0(r9)
    10000728:   2f 80 00 00     cmpwi   cr7,r0,0
    1000072c:   41 9e 00 34     beq-    cr7,10000760 <.matroxfb_probe+0x90>
    10000730:   80 09 00 04     lwz     r0,4(r9)
    10000734:   7f a0 18 00     cmpd    cr7,r0,r3
    10000738:   40 9e ff e8     bne+    cr7,10000720 <.matroxfb_probe+0x50>
    1000073c:   a0 09 00 04     lhz     r0,4(r9)
    10000740:   7f 80 58 40     cmplw   cr7,r0,r11
    10000744:   41 9c ff dc     blt+    cr7,10000720 <.matroxfb_probe+0x50>
    10000748:   38 21 00 90     addi    r1,r1,144
    1000074c:   38 60 00 00     li      r3,0
    10000750:   e8 01 00 10     ld      r0,16(r1)
    10000754:   eb e1 ff f8     ld      r31,-8(r1)
    10000758:   7c 08 03 a6     mtlr    r0
    1000075c:   4e 80 00 20     blr
    10000760:   38 21 00 90     addi    r1,r1,144
    10000764:   38 60 ff ed     li      r3,-19
    10000768:   e8 01 00 10     ld      r0,16(r1)
    1000076c:   eb e1 ff f8     ld      r31,-8(r1)
    10000770:   7c 08 03 a6     mtlr    r0
    10000774:   4e 80 00 20     blr


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug c/26643] Linux matroxfb_probe miscompiled

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-03-11 15:15 -------
(In reply to comment #0)
> I tried all the new opts from -O0 to -O1, but adding them all to -O0 does not
> fix it. No idea why.

Because you did not read the documention that says that would not work.  Now if
you instead used -fno-* to -O1 you might get a better idea.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug c/26643] Linux matroxfb_probe miscompiled

[olh at suse dot de]

------- Comment #5 from olh at suse dot de  2006-03-11 15:21 -------
flags=' -m64 -g -O1 -fno-cprop-registers -fno-defer-pop
-fno-guess-branch-probability -fno-if-conversion -fno-if-conversion2
-fno-ipa-pure-const -fno-ipa-reference -fno-loop-optimize -fno-merge-constants
-fno-omit-frame-pointer -fno-tree-ccp -fno-tree-ch -fno-tree-copy-prop
-fno-tree-copyrename -fno-tree-dce -fno-tree-dominator-opts -fno-tree-dse
-fno-tree-fre -fno-tree-lrs -fno-tree-salias -fno-tree-sink -fno-tree-sra
-fno-tree-ter -fno-unit-at-a-time -fno-var-tracking ' ; gcc -Wall -c -o
~olh/main.o ~olh/main.c $flags && gcc -Wall -c -o ~olh/matroxfb_probe.o
~olh/matroxfb_probe.c $flags && gcc -Wall -o ~olh/matroxfb_probe  ~olh/main.o
~olh/matroxfb_probe.o $flags && ~olh/matroxfb_probe
pci_bus_read_config_byte called (nil) 0 8 0xfffffc24c10
p 0x10011448 -19

doesnt seem to help.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] Linux matroxfb_probe miscompiled

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2006-03-11 15:32 -------
This works on the mainline on powerpc-darwin and on the 4.1 branch on
x86_64-linux-gnu and the mainline on x86_64.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |middle-end
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] Linux matroxfb_probe miscompiled

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2006-03-11 15:35 -------
Can you try "-O1 -fno-ivopts"?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] Linux matroxfb_probe miscompiled

[olh at suse dot de]

------- Comment #8 from olh at suse dot de  2006-03-11 15:56 -------
yes.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] Linux matroxfb_probe miscompiled

[matz at suse dot de]

------- Comment #9 from matz at suse dot de  2006-03-13 08:57 -------
-fno-ivopts fixes it.  The problem is how bitfield refs are dealt with it
seems.  With -fno-ivopts the final_cleanup pass looks like so at the
interesting point:

  D.2180 = BIT_FIELD_REF <*pdev, 32, 544> & 4294967295;
...
  if ((BIT_FIELD_REF <*b, 32, 0> & 4294967295) != D.2180) goto <L3>;
    else goto <L1>;

ivopts lead to this code at that point:

  D.2180 = BIT_FIELD_REF <*pdev, 32, 544> & 4294967295;
...
  if ((MEM[base: (long unsigned int *) b] & 4294967295) != D.2180) goto <L3>;
    else goto <L1>;

Now BIT_FIELD_REF<*b,32,0> extract exactly the 32 bit at address 'b'.
But MEM[base: (long unsigned int *) b] extracts the 64 bit at that address.
The masking afterwards selects the lower 32bit from that, but ppc being
a big endian target this extracts the wrong half.  Let's CC Zdenek for this.


-- 

matz at suse dot de changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.0/4.1/4.2 Regression] Linux matroxfb_probe miscompiled

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
            Summary|Linux matroxfb_probe        |[4.0/4.1/4.2 Regression]
                   |miscompiled                 |Linux matroxfb_probe
                   |                            |miscompiled
   Target Milestone|---                         |4.0.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.0/4.1/4.2 Regression] Linux matroxfb_probe miscompiled

[rakdver at gcc dot gnu dot org]

-- 

rakdver at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rakdver at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-03-13 23:04:23
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.0/4.1/4.2 Regression] Linux matroxfb_probe miscompiled

[rakdver at gcc dot gnu dot org]

------- Comment #10 from rakdver at gcc dot gnu dot org  2006-03-14 01:01 -------
The following patch should fix the problem.  I am fairly sure a similar check
used to be somewhere in ivopts, but it probably got lost when MEM_REFs were
introduced (I am somewhat surprised ivopts do not ICE and produce something
that actually resembles a correct code in this case...)

Index: tree-ssa-loop-ivopts.c
===================================================================
*** tree-ssa-loop-ivopts.c      (revision 111993)
--- tree-ssa-loop-ivopts.c      (working copy)
*************** find_interesting_uses_address (struct iv
*** 1482,1489 ****

    /* Ignore bitfields for now.  Not really something terribly complicated
       to handle.  TODO.  */
!   if (TREE_CODE (base) == COMPONENT_REF
!       && DECL_NONADDRESSABLE_P (TREE_OPERAND (base, 1)))
      goto fail;

    if (STRICT_ALIGNMENT
--- 1482,1490 ----

    /* Ignore bitfields for now.  Not really something terribly complicated
       to handle.  TODO.  */
!   if (TREE_CODE (base) == BIT_FIELD_REF
!       || (TREE_CODE (base) == COMPONENT_REF
!         && DECL_NONADDRESSABLE_P (TREE_OPERAND (base, 1))))
      goto fail;


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.0/4.1/4.2 Regression] Linux matroxfb_probe miscompiled

[rakdver at gcc dot gnu dot org]

------- Comment #11 from rakdver at gcc dot gnu dot org  2006-03-15 13:21 -------
Patch:

http://gcc.gnu.org/ml/gcc-patches/2006-03/msg00925.html


-- 

rakdver at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |http://gcc.gnu.org/ml/gcc-
                   |                            |patches/2006-
                   |                            |03/msg00925.html
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.0/4.1/4.2 Regression] Linux matroxfb_probe miscompiled

[rakdver at gcc dot gnu dot org]

------- Comment #12 from rakdver at gcc dot gnu dot org  2006-03-29 01:34 -------
Subject: Bug 26643

Author: rakdver
Date: Wed Mar 29 01:34:51 2006
New Revision: 112483

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=112483
Log:
        PR tree-optimization/26643
        * tree-ssa-loop-ivopts.c (find_interesting_uses_address): Do not handle
        bit_field_refs.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-ssa-loop-ivopts.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[pinskia at gcc dot gnu dot org]

------- Comment #13 from pinskia at gcc dot gnu dot org  2006-04-11 23:17 -------
Fixed at least on the mainline but still needs to fixed on the 4.1 branch.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.0/4.1/4.2 Regression]    |[4.1 Regression] Linux
                   |Linux matroxfb_probe        |matroxfb_probe miscompiled
                   |miscompiled                 |
   Target Milestone|4.0.4                       |4.1.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[mmitchel at gcc dot gnu dot org]

------- Comment #14 from mmitchel at gcc dot gnu dot org  2006-04-16 19:00 -------
Would some kind person please attempt a backport to 4.1?


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[bonzini at gnu dot org]

------- Comment #15 from bonzini at gnu dot org  2006-04-18 14:12 -------
running a 4.1 bootstrap.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[rguenther at suse dot de]

------- Comment #16 from rguenther at suse dot de  2006-04-18 14:14 -------
Subject: Re:  [4.1 Regression] Linux matroxfb_probe
 miscompiled

> ------- Comment #15 from bonzini at gnu dot org  2006-04-18 14:12 -------
> running a 4.1 bootstrap.

It's been in our SUSE tree for some while and so survived bootstrapping
and testing on x86_64, i686, ppc, ppc64, s390, s390x and ia64.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[bonzini at gcc dot gnu dot org]

------- Comment #17 from bonzini at gnu dot org  2006-04-18 14:23 -------
Subject: Bug 26643

Author: bonzini
Date: Tue Apr 18 14:22:59 2006
New Revision: 113041

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=113041
Log:
2006-04-18  Paolo Bonzini  <bonzini@gnu.org>

        PR tree-optimization/26643

        Backport from mainline:
        2006-03-29  Zdenek Dvorak <dvorakz@suse.cz>

        PR tree-optimization/26643
        * tree-ssa-loop-ivopts.c (find_interesting_uses_address): Do not handle
        bit_field_refs.


Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/tree-ssa-loop-ivopts.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643

[Bug middle-end/26643] [4.1 Regression] Linux matroxfb_probe miscompiled

[bonzini at gnu dot org]

------- Comment #18 from bonzini at gnu dot org  2006-04-18 14:23 -------
patch committed to 4.1 too.


-- 

bonzini at gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26643