[Bug tree-optimization/56494] New: ICE in simplify_truncation, at simplify-rtx.c:619

[Bug tree-optimization/56494] New: ICE in simplify_truncation, at simplify-rtx.c:619

[antoine.balestrat at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

             Bug #: 56494
           Summary: ICE in simplify_truncation, at simplify-rtx.c:619
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: antoine.balestrat@gmail.com


With GCC 4.8.0 as of 20130301 :

$ cat trunc.c
char a;
short b;

void f(void)
{
    g((!!b ? : (a *= a / 0)) >= (a = b));
}

$ xgcc -w -O2 -ftracer trunc.c
trunc.c: In function ‘f’:
trunc.c:7:1: internal compiler error: in simplify_truncation, at
simplify-rtx.c:619
 }
 ^
0x8db526 simplify_truncation
    ../../srcdir/gcc/simplify-rtx.c:619
0x8dc6fa simplify_unary_operation_1
    ../../srcdir/gcc/simplify-rtx.c:1046
0x8dc6fa simplify_unary_operation(rtx_code, machine_mode, rtx_def*,
machine_mode)
    ../../srcdir/gcc/simplify-rtx.c:786
0x8de2ef simplify_gen_unary(rtx_code, machine_mode, rtx_def*, machine_mode)
    ../../srcdir/gcc/simplify-rtx.c:369
0x8dc6fa simplify_unary_operation_1
    ../../srcdir/gcc/simplify-rtx.c:1046
0x8dc6fa simplify_unary_operation(rtx_code, machine_mode, rtx_def*,
machine_mode)
    ../../srcdir/gcc/simplify-rtx.c:786
0x8de2ef simplify_gen_unary(rtx_code, machine_mode, rtx_def*, machine_mode)
    ../../srcdir/gcc/simplify-rtx.c:369
0x8db057 simplify_truncation
    ../../srcdir/gcc/simplify-rtx.c:648
0x8dbc2d simplify_gen_subreg(machine_mode, rtx_def*, machine_mode, unsigned
int)
    ../../srcdir/gcc/simplify-rtx.c:5942
0xce9dce gen_lowpart_for_combine
    ../../srcdir/gcc/combine.c:10732
0xcef08e expand_compound_operation
    ../../srcdir/gcc/combine.c:6808
0xcf481f simplify_comparison
    ../../srcdir/gcc/combine.c:11168
0xcf754e combine_simplify_rtx
    ../../srcdir/gcc/combine.c:5665
0xcf972a subst
    ../../srcdir/gcc/combine.c:5155
0xcf93da subst
    ../../srcdir/gcc/combine.c:5100
0xcfa92f try_combine
    ../../srcdir/gcc/combine.c:3146
0xcff76c combine_instructions
    ../../srcdir/gcc/combine.c:1368
0xcff76c rest_of_handle_combine
    ../../srcdir/gcc/combine.c:13793
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-03-04
                 CC|                            |mpolacek at gcc dot gnu.org
      Known to work|                            |4.7.3
            Summary|ICE in simplify_truncation, |[4.8 Regression] ICE in
                   |at simplify-rtx.c:619       |simplify_truncation, at
                   |                            |simplify-rtx.c:619
     Ever Confirmed|0                           |1
      Known to fail|                            |4.8.0

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> 2013-03-04 09:49:02 UTC ---
Confirmed.

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |rsandifo at gcc dot gnu.org
   Target Milestone|---                         |4.8.0

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-04 10:11:39 UTC ---
Caused by http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=192186

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-04 10:46:34 UTC ---
Created attachment 29578
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29578
gcc48-pr56494.patch

Untested fix.

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[rdsandiford at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

--- Comment #4 from rdsandiford at googlemail dot com <rdsandiford at googlemail dot com> 2013-03-04 21:06:10 UTC ---
"jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> writes:
> Created attachment 29578
>   --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29578
> gcc48-pr56494.patch

Thanks for the fix.  Looks good to me FWIW.  Truncations can't be to a
narrower mode (already asserted at the top of the function) so in some
ways I think it would be clearer to have an "if ... else" rather than
two "if"s.

Richard

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 06:04:23 UTC ---
Author: jakub
Date: Tue Mar  5 06:04:14 2013
New Revision: 196451

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196451
Log:
    PR rtl-optimization/56494
    * simplify-rtx.c (simplify_truncation): If C is narrower than A,
    optimize (truncate:A (subreg:B (truncate:C X) 0)) into
    (subreg:A (truncate:C X) 0) instead of (truncate:A X).

    * gcc.dg/pr56494.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr56494.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/simplify-rtx.c
    trunk/gcc/testsuite/ChangeLog

[Bug rtl-optimization/56494] [4.8 Regression] ICE in simplify_truncation, at simplify-rtx.c:619

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56494

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

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05 06:24:01 UTC ---
Fixed.