[Bug c++/68021] New: ice in rewrite_use_nonlinear_expr with -O3

[Bug c++/68021] New: ice in rewrite_use_nonlinear_expr with -O3

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

            Bug ID: 68021
           Summary: ice in rewrite_use_nonlinear_expr with -O3
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Created attachment 36540
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36540&action=edit
C++ source code

For today's trunk gcc on x64_64

$ ../results/bin/g++ -O3 -c bug237.cc
svga_cirrus.cc: In function ‘void bitblt_rop_bkwd_src_and_dst(Bit8u*, const
Bit8u*, int, int, int, int)’:
svga_cirrus.cc:3304:13: internal compiler error: in rewrite_use_nonlinear_expr,
at tree-ssa-loop-ivopts.c:6916
0xf044d4 rewrite_use_nonlinear_expr
        ../../src/trunk/gcc/tree-ssa-loop-ivopts.c:6916
0xf044d4 rewrite_use
        ../../src/trunk/gcc/tree-ssa-loop-ivopts.c:7177
0xf044d4 rewrite_uses
        ../../src/trunk/gcc/tree-ssa-loop-ivopts.c:7210
0xf0b190 tree_ssa_iv_optimize_loop
        ../../src/trunk/gcc/tree-ssa-loop-ivopts.c:7550
0xf0b190 tree_ssa_iv_optimize()
        ../../src/trunk/gcc/tree-ssa-loop-ivopts.c:7582
0xf24fc0 execute
        ../../src/trunk/gcc/tree-ssa-loop.c:412
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.

tree-ssa-loop-ivopts.c:6916 is

  gcc_assert (comp != NULL_TREE);
>From gcc-bugs-return-499958-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Mon Oct 19 18:16:13 2015
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Subject: [Bug fortran/67987] ICE on declaring and initializing character with negative len
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idg987

--- Comment #6 from kargl at gcc dot gnu.org ---
Author: kargl
Date: Mon Oct 19 18:15:36 2015
New Revision: 228999

URL: https://gcc.gnu.org/viewcvs?rev"8999&root=gcc&view=rev
Log:
2015-10-19  Steven G. Kargl  <kargl@gcc.gnu.org>

        PR fortran/67987
        * decl.c (char_len_param_value): Unwrap unlong line.  If LEN < 0,
        force it to zero per the Fortran 90, 95, 2003, and 2008 Standards.
        * resolve.c (gfc_resolve_substring_charlen): Unwrap unlong line.
        If 'start' is larger than 'end', length of substring is negative,
        so explicitly set it to zero.
        (resolve_charlen): Remove -Wsurprising warning.  Update comment to
        reflect that the text is from the F2008 standard.

2015-10-19  Steven G. Kargl  <kargl@gcc.gnu.org>

        PR fortran/67987
        * gfortran.df/pr67987.f90: New test.
        * gfortran.dg/char_length_2.f90: Update testcase.

Added:
    branches/gcc-5-branch/gcc/testsuite/gfortran.dg/pr67987.f90
Modified:
    branches/gcc-5-branch/gcc/fortran/ChangeLog
    branches/gcc-5-branch/gcc/fortran/decl.c
    branches/gcc-5-branch/gcc/fortran/resolve.c
    branches/gcc-5-branch/gcc/testsuite/ChangeLog
    branches/gcc-5-branch/gcc/testsuite/gfortran.dg/char_length_2.f90

[Bug tree-optimization/68021] [6 Regression] ice in rewrite_use_nonlinear_expr with -O3

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |6.0

[Bug tree-optimization/68021] [6 Regression] ice in rewrite_use_nonlinear_expr with -O3

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r228599.

[Bug tree-optimization/68021] [6 Regression] ice in rewrite_use_nonlinear_expr with -O3

[ysrumyan at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

--- Comment #3 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
It looks like unswitching of outer loops pass simply triggers the issue and
this tree-ssa-loop-ivopts issue.

[Bug tree-optimization/68021] [6 Regression] ice in rewrite_use_nonlinear_expr with -O3

[ysrumyan at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

--- Comment #4 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
Indeed, there is an issue with outer-loop unswitching - it should not be
performed for infinite loops. But if we slightly modify test if finite
outer-loop we will get the same error: 
char a;
void fn1(char *p1, int p2, int p3) {
  int i, x;
  for (i = 0; i < 10; i++) {
    for (x = 0; x < p3; x++) {
      *p1 = a;
      p1--;
    }
    p1 += p2;
  }
}

I assume that  sccp is responsible for it.

[Bug tree-optimization/68021] [6 Regression] ice in rewrite_use_nonlinear_expr with -O3

[ysrumyan at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021

--- Comment #5 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
Hi HJ

I added my evaluation to bug. It looks like my changes are not
responsible for ICE.

2015-10-20 13:20 GMT+03:00 hjl.tools at gmail dot com
<gcc-bugzilla@gcc.gnu.org>:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68021
>
> H.J. Lu <hjl.tools at gmail dot com> changed:
>
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |ysrumyan at gmail dot com
>
> --
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