[Bug middle-end/47653] New: [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[Bug middle-end/47653] New: [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

           Summary: [4.6 Regression] gcc.c-torture/execute/930614-2.c
                    FAILs with -fstack-check=generic -fgraphite-identity
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
                CC: spop@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23280
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23280
reduced testcase

Output:
$ gcc -v
Using built-in specs.
COLLECT_GCC=/mnt/svn/gcc-trunk/binary-169929-lto-fortran-checking-yes-rtl-df/bin/gcc
COLLECT_LTO_WRAPPER=/mnt/svn/gcc-trunk/binary-169929-lto-fortran-checking-yes-rtl-df/libexec/gcc/x86_64-unknown-linux-gnu/4.6.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /mnt/svn/gcc-trunk//configure --enable-checking=yes,rtl,df
--enable-languages=c,c++,lto,fortran
--prefix=/mnt/svn/gcc-trunk/binary-169929-lto-fortran-checking-yes-rtl-df/
--with-cloog --with-ppl --with-cloog-include=/usr/include/cloog-ppl/
Thread model: posix
gcc version 4.6.0 20110208 (experimental) (GCC) 

$ gcc -O -fstack-check=generic -ftree-pre -fgraphite-identity testcase.c
$ ./a.out 
Segmentation fault

Program received signal SIGSEGV, Segmentation fault.
0x0000000000400552 in main () at testcase.c:7
7             x[i][j] = 0;
(gdb) disassemble
   0x0000000000400549 <+101>:   lea    (%rcx,%rax,1),%edx
   0x000000000040054c <+104>:   movslq %edx,%rdx
   0x000000000040054f <+107>:   add    %rsi,%rdx
=> 0x0000000000400552 <+110>:   movl   $0x0,(%r8,%rdx,4)
   0x000000000040055a <+118>:   add    $0x1,%rax
   0x000000000040055e <+122>:   lea    -0x1(%rax),%rdx
   0x0000000000400562 <+126>:   cmp    %rdi,%rdx
   0x0000000000400565 <+129>:   jl     0x400549 <main+101>

Tested revisions:
r169929 - fail
4.5.2 - OK

[Bug middle-end/47653] [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.02.09 03:56:58
   Target Milestone|---                         |4.6.0
     Ever Confirmed|0                           |1

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2011-02-09 03:56:58 UTC ---
It is caused by revision 168211:

http://gcc.gnu.org/ml/gcc-cvs/2010-12/msg00896.html

[Bug middle-end/47653] [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Jeffrey A. Law <law at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
                 CC|                            |law at redhat dot com
         AssignedTo|unassigned at gcc dot       |spop at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #2 from Jeffrey A. Law <law at redhat dot com> 2011-02-18 15:36:46 UTC ---
This appears to be a bug in the graphite transformations. Prior to graphite
transformations we have the following function with two nested loops:

  # BLOCK 2 freq:139
  # PRED: ENTRY [100.0%]  (fallthru,exec)
  # .MEM_13 = VDEF <.MEM_12(D)>
  saved_stack.1_3 = __builtin_stack_save ();
  # .MEM_14 = VDEF <.MEM_13>
  x.0_4 = __builtin_alloca (256);
  goto <bb 8>;
  # SUCC: 8 [100.0%]  (fallthru,exec)

  # BLOCK 3 freq:7901
  # PRED: 4 [88.9%]  (true,exec)
  # SUCC: 4 [100.0%]  (fallthru,exec)

  # BLOCK 4 freq:8889
  # PRED: 3 [100.0%]  (fallthru,exec) 9 [100.0%]  (fallthru,exec)
  # j_23 = PHI <j_7(3), j_5(9)>
  # .MEM_24 = PHI <.MEM_15(3), .MEM_6(9)>
  # .MEM_15 = VDEF <.MEM_24>
  *x.0_4[j_5][j_23] = 0;
  j_7 = j_23 + 1;
  if (j_7 <= 7)
    goto <bb 3>;
  else
    goto <bb 5>;
  # SUCC: 3 [88.9%]  (true,exec) 5 [11.1%]  (false,exec)

  # BLOCK 5 freq:988
  # PRED: 4 [11.1%]  (false,exec)
  # .MEM_19 = PHI <.MEM_15(4)>
  # SUCC: 6 [100.0%]  (fallthru,exec)

  # BLOCK 6 freq:1111
  # PRED: 5 [100.0%]  (fallthru,exec) 8 [11.1%]  (false,exec)
  # .MEM_25 = PHI <.MEM_19(5), .MEM_6(8)>
  i_8 = j_5 + 1;
  if (i_8 <= 7)
    goto <bb 7>;
  else
    goto <bb 10>;
  # SUCC: 7 [88.9%]  (true,exec) 10 [11.1%]  (false,exec)

  # BLOCK 7 freq:988
  # PRED: 6 [88.9%]  (true,exec)
  # SUCC: 8 [100.0%]  (fallthru,exec)

  # BLOCK 8 freq:1111
  # PRED: 7 [100.0%]  (fallthru,exec) 2 [100.0%]  (fallthru,exec)
  # j_5 = PHI <i_8(7), 0(2)>
  # .MEM_6 = PHI <.MEM_25(7), .MEM_14(2)>
  if (j_5 <= 7)
    goto <bb 9>;
  else
    goto <bb 6>;
  # SUCC: 9 [88.9%]  (true,exec) 6 [11.1%]  (false,exec)

  # BLOCK 9 freq:988
  # PRED: 8 [88.9%]  (true,exec)
  goto <bb 4>;
  # SUCC: 4 [100.0%]  (fallthru,exec)

  # BLOCK 10 freq:139
  # PRED: 6 [11.1%]  (false,exec)
  # .MEM_16 = VDEF <.MEM_25>
  __builtin_stack_restore (saved_stack.1_3);
  return 0;
  # SUCC: EXIT [100.0%]

Pretty simple stuff.

Graphite transforms it into:

  # BLOCK 2 freq:313
  # PRED: ENTRY [100.0%]  (fallthru,exec)
  # .MEM_13 = VDEF <.MEM_12(D)>
  saved_stack.1_3 = __builtin_stack_save ();
  # .MEM_14 = VDEF <.MEM_13>
  x.0_4 = __builtin_alloca (256);
  # SUCC: 3 [100.0%]  (fallthru)

  # BLOCK 3 freq:2500
  # PRED: 2 [100.0%]  (fallthru) 8 [100.0%]  (fallthru,dfs_back)
  # graphite_IV.5_11 = PHI <0(2), graphite_IV.5_1(8)>
  # .MEM_33 = PHI <.MEM_14(2), .MEM_34(8)>
  D.2701_22 = 8 - graphite_IV.5_11;
  D.2702_21 = D.2701_22 > 0;
  if (D.2702_21 != 0)
    goto <bb 4>;
  else
    goto <bb 7>;
  # SUCC: 4 [50.0%]  (true) 7 [50.0%]  (false)

  # BLOCK 4 freq:1250
  # PRED: 3 [50.0%]  (true)
  D.2704_10 = (<unnamed-signed:64>) graphite_IV.5_11;
  D.2705_2 = D.2704_10 * 4294967295;
  D.2706_18 = D.2705_2 + 7;
  # SUCC: 5 [100.0%]  (fallthru)

  # BLOCK 5 freq:10000
  # PRED: 4 [100.0%]  (fallthru) 6 [100.0%]  (fallthru,dfs_back)
  # graphite_IV.6_17 = PHI <0(4), graphite_IV.6_26(6)>
  # .MEM_35 = PHI <.MEM_33(4), .MEM_27(6)>
  D.2707_28 = (int) graphite_IV.5_11;
  D.2708_29 = (int) graphite_IV.5_11;
  D.2709_30 = (int) graphite_IV.6_17;
  D.2710_31 = D.2708_29 + D.2709_30;
  # .MEM_27 = VDEF <.MEM_35>
  *x.0_4[D.2707_28][D.2710_31] = 0;
  graphite_IV.6_26 = graphite_IV.6_17 + 1;
  if (graphite_IV.6_17 < D.2706_18)
    goto <bb 6>;
  else
    goto <bb 7>;
  # SUCC: 6 [87.5%]  (true) 7 [12.5%]  (loop_exit,false)

  # BLOCK 6 freq:8750
  # PRED: 5 [87.5%]  (true)
  goto <bb 5>;
  # SUCC: 5 [100.0%]  (fallthru,dfs_back)

  # BLOCK 7 freq:2500
  # PRED: 5 [12.5%]  (loop_exit,false) 3 [50.0%]  (false)
  # .MEM_34 = PHI <.MEM_27(5), .MEM_33(3)>
  graphite_IV.5_1 = graphite_IV.5_11 + 1;
  if (graphite_IV.5_11 < 7)
    goto <bb 8>;
  else
    goto <bb 9>;
  # SUCC: 8 [87.5%]  (true) 9 [12.5%]  (loop_exit,false)

  # BLOCK 8 freq:2188
  # PRED: 7 [87.5%]  (true)
  goto <bb 3>;
  # SUCC: 3 [100.0%]  (fallthru,dfs_back)

  # BLOCK 9 freq:313
  # PRED: 7 [12.5%]  (loop_exit,false)
  # .MEM_32 = PHI <.MEM_34(7)>
  # .MEM_16 = VDEF <.MEM_32>
  __builtin_stack_restore (saved_stack.1_3);
  return 0;
  # SUCC: EXIT [100.0%]


Of particular interest is the assignment to D.2705_2 in block #4:

  D.2705_2 = D.2704_10 * 4294967295;
  D.2706_18 = D.2705_2 + 7;

That makes absolutely no sense.  Particularly since D.2706_18 is later used to
control loop termination in BB5.    Note D.2706 is a 64bit type, so we really
are multiplying by 4294967295.  Needless to say this causes the loop
termination condition to do something different than was originally intended.

[Bug middle-end/47653] [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Sebastian Pop <spop at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #3 from Sebastian Pop <spop at gcc dot gnu.org> 2011-02-18 16:58:02 UTC ---
Thanks jeff for analyzing the cause of this bug: indeed
D.2705_2 = D.2704_10 * 4294967295;
doesn't seem to be correct.

Looking at the patch that introduced this bug, it is clear that this stmt
should have been:
D.2705_2 = D.2704_10 * -1;

[Bug middle-end/47653] [4.6 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

--- Comment #4 from Sebastian Pop <spop at gcc dot gnu.org> 2011-02-18 18:28:13 UTC ---
http://gcc.gnu.org/viewcvs?view=revision&revision=168211
removed all the uses of int_cst_value and replaced them with
tree_int_to_gmp, and here is what happens:

Breakpoint 5, scan_tree_for_params_right_scev (s=0x190a300, e=0x7ffff7ec96b8,
var=1, expr=0x190cb20) at ../../gcc/graphite-sese-to-poly.c:637
(gdb) p e
$1 = (tree) 0x7ffff7ec96b8
(gdb) pgs
4294967295

(gdb) p int_cst_value (e)
$2 = -1
(gdb) p e
$3 = (tree) 0x7ffff7ec96b8
(gdb) pt
 <integer_cst 0x7ffff7ec96b8 type <integer_type 0x7ffff7edc540 unsigned int>
constant 4294967295>

The reason int_cst_value returns -1 is that it sign extends the value:

  unsigned HOST_WIDE_INT val = TREE_INT_CST_LOW (x);
      bool negative = ((val >> (bits - 1)) & 1) != 0;
      if (negative)
    val |= (~(unsigned HOST_WIDE_INT) 0) << (bits - 1) << 1;

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.6.0                       |4.6.1

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-03-25 19:52:36 UTC ---
GCC 4.6.0 is being released, adjusting target milestone.

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.6.1                       |4.6.2

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-06-27 12:32:49 UTC ---
GCC 4.6.1 is being released.

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

--- Comment #7 from Sebastian Pop <spop at gcc dot gnu.org> 2011-06-29 21:18:09 UTC ---
Patch http://gcc.gnu.org/ml/gcc-patches/2011-06/msg02283.html

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

--- Comment #8 from Sebastian Pop <spop at gcc dot gnu.org> 2011-07-25 17:46:29 UTC ---
Second attempt to fix this PR:
http://gcc.gnu.org/ml/gcc-patches/2011-07/msg02061.html

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Sebastian Pop <spop at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |howarth at nitro dot
                   |                            |med.uc.edu

--- Comment #9 from Sebastian Pop <spop at gcc dot gnu.org> 2011-07-25 17:47:33 UTC ---
*** Bug 47593 has been marked as a duplicate of this bug. ***

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

--- Comment #10 from Sebastian Pop <spop at gcc dot gnu.org> 2011-07-26 18:48:19 UTC ---
Author: spop
Date: Tue Jul 26 18:48:08 2011
New Revision: 176802

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176802
Log:
Fix PR47653: do not handle loops using wrapping semantics in graphite

2011-07-26  Sebastian Pop  <sebastian.pop@amd.com>

    PR middle-end/47653
    * graphite-scop-detection.c (graphite_can_represent_loop): Discard
    loops using wrapping semantics.

    * gcc.dg/graphite/run-id-pr47653.c: New.
    * gcc.dg/graphite/interchange-3.c: Do not use unsigned types for
    induction variables.
    * gcc.dg/graphite/scop-16.c: Same.
    * gcc.dg/graphite/scop-17.c: Same.
    * gcc.dg/graphite/scop-21.c: Same.

Added:
    trunk/gcc/testsuite/gcc.dg/graphite/run-id-pr47653.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/graphite-scop-detection.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/graphite/interchange-3.c
    trunk/gcc/testsuite/gcc.dg/graphite/scop-16.c
    trunk/gcc/testsuite/gcc.dg/graphite/scop-17.c
    trunk/gcc/testsuite/gcc.dg/graphite/scop-21.c
    trunk/libgomp/testsuite/libgomp.graphite/force-parallel-1.c

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

--- Comment #11 from Sebastian Pop <spop at gcc dot gnu.org> 2011-07-26 18:48:32 UTC ---
Author: spop
Date: Tue Jul 26 18:48:20 2011
New Revision: 176803

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176803
Log:
Add testcase for PR47593

2011-07-26  Sebastian Pop  <sebastian.pop@amd.com>

    PR middle-end/47653
    * gcc.dg/graphite/run-id-pr47593.c: New.

Added:
    trunk/gcc/testsuite/gcc.dg/graphite/run-id-pr47593.c
Modified:
    trunk/gcc/testsuite/ChangeLog

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[spop at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Sebastian Pop <spop at gcc dot gnu.org> changed:

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

--- Comment #12 from Sebastian Pop <spop at gcc dot gnu.org> 2011-07-26 18:56:23 UTC ---
Fixed.

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[ro at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |ro at gcc dot gnu.org
         Resolution|FIXED                       |

--- Comment #13 from Rainer Orth <ro at gcc dot gnu.org> 2011-08-09 15:52:05 UTC ---
Unfortunately, hardcoding -m32 in gcc.dg/graphite/run-id-pr47593.c doesn't work
on several targets (like mips-sgi-irix6.5):

FAIL: gcc.dg/graphite/run-id-pr47593.c (test for excess errors)
Excess errors:
xgcc: error: unrecognized command line option '-m32'

The flag wasn't in the patch submission and I have no idea why it was added.
Do you mean something like target ilp32?

  Rainer

[Bug middle-end/47653] [4.6/4.7 Regression] gcc.c-torture/execute/930614-2.c FAILs with -fstack-check=generic -fgraphite-identity

[matz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47653

Michael Matz <matz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
                 CC|                            |matz at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #14 from Michael Matz <matz at gcc dot gnu.org> 2011-08-11 13:44:14 UTC ---
Removed the m32 in r177666.