[Bug debug/48150] New: [4.7 Regression] gcc.dg/guality/sra-1.c

[Bug debug/48150] New: [4.7 Regression] gcc.dg/guality/sra-1.c

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

           Summary: [4.7 Regression] gcc.dg/guality/sra-1.c
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com
                CC: rguenth@gcc.gnu.org


On Linux/Intel64, revision 171044 gave

FAIL: gcc.dg/guality/sra-1.c  -O2  line 43 a.j == 14
FAIL: gcc.dg/guality/sra-1.c  -O3 -g  line 43 a.j == 14
FAIL: gcc.dg/guality/sra-1.c  -Os  line 43 a.j == 14

Revision 171042 is OK. It is caused by revision 171043:

http://gcc.gnu.org/ml/gcc-cvs/2011-03/msg00465.html

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|4.6.0                       |4.7.0
   Target Milestone|---                         |4.7.0

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-16 16:17:04 UTC ---
Can't reproduce it.

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|4.7.0                       |4.6.0
   Target Milestone|4.7.0                       |---

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-03-16 16:23:50 UTC ---
(In reply to comment #1)
> Can't reproduce it.

Have you tried GDB 7.2?

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[rguenther at suse dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

--- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> 2011-03-16 16:33:25 UTC ---
On Wed, 16 Mar 2011, hjl.tools at gmail dot com wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150
> 
> H.J. Lu <hjl.tools at gmail dot com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>             Version|4.7.0                       |4.6.0
>    Target Milestone|4.7.0                       |---
> 
> --- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-03-16 16:23:50 UTC ---
> (In reply to comment #1)
> > Can't reproduce it.
> 
> Have you tried GDB 7.2?

I'm using gdb-7.2.50.20110206-67.1

Richard.

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.0

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-10-10
                 CC|                            |jakub at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-10 11:39:47 UTC ---
I only see

FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.i == 4
FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.j == 14

now with gdb 7.3.

43        bar (a.j);            /* { dg-final { gdb-test 43 "a.j" "14" } } */^M
$1 = 0^M
$2 = 4^M
0 != 4
FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.i == 4

43        bar (a.j);            /* { dg-final { gdb-test 43 "a.j" "14" } } */^M
$1 = 0^M
$2 = 14^M
A debugging session is active.^M
^M
        Inferior 1 [process 4603] will be killed.^M
^M
0 != 14
FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.j == 14

manually debugging yields

(gdb) b 43
(gdb) run
(gdb) p a.j
$1 = 0
(gdb) p a.i
$2 = 0
(gdb) p a
$3 = <optimized out>

The location list looks like

    000002ec 0000000000400581 0000000000400586 (DW_OP_bit_piece: size: 4
offset:
 0 ; DW_OP_lit4; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ;
DW_OP_
breg5 (rdi): 6; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ;
DW_OP_b
it_piece: size: 4 offset: 0 )
    000002ec 0000000000400586 000000000040058b (DW_OP_bit_piece: size: 4
offset:
 0 ; DW_OP_reg0 (rax); DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_breg5 (rdi): 
7; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_bit_piece:
siz
e: 4 offset: 0 )
    000002ec 000000000040058b 000000000040058f (DW_OP_bit_piece: size: 4
offset:
 0 ; DW_OP_reg0 (rax); DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_breg3 (rbx): 
7; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_bit_piece:
siz
e: 4 offset: 0 )
    000002ec 000000000040058f 0000000000400593 (DW_OP_bit_piece: size: 4
offset:
 0 ; DW_OP_reg6 (rbp); DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_breg3 (rbx): 
7; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_bit_piece:
siz
e: 4 offset: 0 )
    000002ec 0000000000400593 00000000004005b1 (DW_OP_bit_piece: size: 4
offset:
 0 ; DW_OP_reg6 (rbp); DW_OP_bit_piece: size: 12 offset: 0 ; (User defined
locat
ion op))
    000002ec 00000000004005b1 00000000004005b6 (DW_OP_piece: 2; (User defined
lo
cation op))
    000002ec <End of list>

which is weird because of the size: 12 entries(?)

Jakub?

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
            Version|4.6.0                       |4.7.0

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-27 09:34:15 UTC ---
Well, I suppose we should at least investigate.

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-24 14:44:57 UTC ---
Yeah, can't reproduce -O2/-O3/-Os issues, but can reproduce
FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.i == 4
FAIL: gcc.dg/guality/sra-1.c  -O1  line 43 a.j == 14
with gdb-7.3.50.20110722-10.fc16.x86_64.
With
GUALITY_GDB_NAME=/usr/src/gdb/obj/gdb/gdb \
make check-gcc RUNTESTFLAGS='guality.exp=sra-1.c'
where that gdb is current trunk gdb I can't reproduce it though, entry_value
works for that case well.
line 43 a.i == 4 test I'd assume it would work fine with latest trunk gdb even
if no entry_value could be looked up:
  4004fb:       e8 74 ff ff ff          callq  400474 <bar>
  400500:       c1 e3 04                shl    $0x4,%ebx
  400503:       83 c3 70                add    $0x70,%ebx
  400506:       66 c1 fb 04             sar    $0x4,%bx
  40050a:       0f bf db                movswl %bx,%ebx
  40050d:       89 df                   mov    %ebx,%edi
  40050f:       e8 60 ff ff ff          callq  400474 <bar>
with
    000002c2 00000000004004fb 00000000004004ff (DW_OP_bit_piece: size: 4
offset: 0 ; DW_OP_reg0 (rax); DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_breg3
(rbx): 7; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ;
DW_OP_bit_piece: size: 4 offset: 0 )
    000002c2 00000000004004ff 0000000000400503 (DW_OP_bit_piece: size: 4
offset: 0 ; DW_OP_reg6 (rbp); DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_breg3
(rbx): 7; DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ;
DW_OP_bit_piece: size: 4 offset: 0 )
    000002c2 0000000000400503 0000000000400521 (DW_OP_bit_piece: size: 4
offset: 0 ; DW_OP_reg6 (rbp); DW_OP_bit_piece: size: 12 offset: 0 ;
DW_OP_GNU_entry_value: (DW_OP_reg5 (rdi)); DW_OP_plus_uconst: 7;
DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_bit_piece: size:
4 offset: 0 )
    000002c2 0000000000400521 0000000000400526 (DW_OP_piece: 2;
DW_OP_GNU_entry_value: (DW_OP_reg5 (rdi)); DW_OP_plus_uconst: 7;
DW_OP_stack_value; DW_OP_bit_piece: size: 12 offset: 0 ; DW_OP_bit_piece: size:
4 offset: 0 )
    000002c2 <End of list>
doesn't work with older gdb just because there is the unhandled
DW_OP_GNU_entry_value in the expression and gdb gives up even when it doesn't
affect the a.i bitfield part which lives properly in low bits of $rbp.
The line 43 a.j == 14 case is much more complicated at -O1.  The problem is
that
we have 12-bit precision arithmetics done for -O1 and thus we end up with:
(debug_insn 14 13 15 2 (var_location:HI a$j (plus:HI (subreg:HI (reg/v:SI 3 bx
[orig:69 k ] [69]) 0)
        (const_int 7 [0x7]))) sra-1.c:41 -1
     (nil))
...
(insn 40 18 20 2 (parallel [
            (set (reg:SI 3 bx [73])
                (ashift:SI (reg:SI 3 bx [orig:69 k ] [69])
                    (const_int 4 [0x4])))
            (clobber (reg:CC 17 flags))
        ]) sra-1.c:39 499 {*ashlsi3_1}
     (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))
...
(insn 41 21 23 2 (parallel [
            (set (reg:SI 3 bx [76])
                (plus:SI (reg:SI 3 bx [73])
                    (const_int 112 [0x70])))
            (clobber (reg:CC 17 flags))
        ]) sra-1.c:41 253 {*addsi_1}
     (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))

(insn 23 41 24 2 (parallel [
            (set (reg:HI 3 bx [77])
                (ashiftrt:HI (reg:HI 3 bx [76])
                    (const_int 4 [0x4])))
            (clobber (reg:CC 17 flags))
        ]) sra-1.c:41 543 {*ashrhi3_1}
     (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))

(insn 24 23 25 2 (set (reg:SI 3 bx [orig:65 D.2953 ] [65])
        (sign_extend:SI (reg:HI 3 bx [77]))) sra-1.c:43 128 {extendhisi2}
     (nil))

And var-tracking works on VALUEs with modes, not on weirdo precision types.
If var-tracking would track somehow that it is only interested in low 12 bits
of the value, then it could throgh the above insns figure out that those 12
bits
are first shifted up by 4, then 112 added and then shifted down by 4, thus
low 12 bits of bx in the end contain the right 12 bits with 7 added to it.

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-24 14:58:30 UTC ---
Perhaps we could use as value of a$j SIGN_EXTRACT from the provided VALUE,
i.e. when a$j is 12-bit, assume
(debug_insn 14 13 15 2 (var_location:HI a$j (plus:HI (sign_extract:HI (reg/v:SI
3 bx [orig:69 k ] [69]) (const_int 12) (const_int 0))
        (const_int 7 [0x7]))) sra-1.c:41 -1
     (nil))
instead of
(debug_insn 14 13 15 2 (var_location:HI a$j (plus:HI (subreg:HI (reg/v:SI 3 bx
[orig:69 k ] [69]) 0)
        (const_int 7 [0x7]))) sra-1.c:41 -1
     (nil))
and then on shift left, reversable operation and shift right note that the
value
for the sign_extract would live in (sign_extract:HI (value of bx after shift
left) (const_int 12) (const_int 4)) after the left shift, etc.

I guess it would be pretty difficult and for not very common case though.

[Bug debug/48150] [4.7 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P1                          |P2

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-25 09:13:56 UTC ---
Anyway, not really a P1 severity issue.

[Bug debug/48150] [4.7/4.8 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.0                       |4.7.1

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-22 08:26:13 UTC ---
GCC 4.7.0 is being released, adjusting target milestone.

[Bug debug/48150] [4.7/4.8 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.1                       |4.7.2

--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-14 08:17:30 UTC ---
GCC 4.7.1 is being released, adjusting target milestone.

[Bug debug/48150] [4.7/4.8 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.2                       |4.7.3

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-09-20 10:13:21 UTC ---
GCC 4.7.2 has been released.

[Bug debug/48150] [4.7/4.8/4.9 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.3                       |4.7.4

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-11 07:58:57 UTC ---
GCC 4.7.3 is being released, adjusting target milestone.

[Bug debug/48150] [4.7/4.8/4.9/4.10 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.4                       |4.8.4

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
The 4.7 branch is being closed, moving target milestone to 4.8.4.

[Bug debug/48150] [4.8/4.9/5 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.4                       |4.8.5

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.4 has been released.

[Bug debug/48150] [4.8/4.9/5/6 Regression] gcc.dg/guality/sra-1.c

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.5                       |4.9.3

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
The gcc-4_8-branch is being closed, re-targeting regressions to 4.9.3.

[Bug debug/48150] [4.9/5/6 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.9.3 has been released.

[Bug debug/48150] [4.9/5/6 Regression] gcc.dg/guality/sra-1.c

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48150

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.3                       |4.9.4