[Bug tree-optimization/68455] New: [6 Regression] ICE: tree check: expected integer_cst, have plus_expr in decompose, at tree.h:5123

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68455

            Bug ID: 68455
           Summary: [6 Regression] ICE: tree check: expected integer_cst,
                    have plus_expr in decompose, at tree.h:5123
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

The following reduced testcase triggers ICE for gcc-6.0.0-alpha20151115 when
compiling at -O2, -O3, -Os, or -Ofast:

int gb;
int uz;

void
si(void)
{
  int ew;

  for (ew = 0; ew < 1; ++ew) {
    unsigned short int ng;

    if (ng < uz)
      gb = 1 / uz;
  }
}

% gcc-6.0.0-alpha20151115 -c -O2 l9ypxxol.c
l9ypxxol.c: In function 'si':
l9ypxxol.c:5:1: internal compiler error: tree check: expected integer_cst, have
plus_expr in decompose, at tree.h:5123
 si(void)
 ^~

I cannot reproduce it w/ gcc-6.0.0-alpha20150802, though.