[Bug tree-optimization/68493] New: [6 Regression] [graphite] ICE in copy_loop_phi_args

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68493

            Bug ID: 68493
           Summary: [6 Regression] [graphite] ICE in copy_loop_phi_args
           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: ---

1. 6.0.0-alpha20151115 ICEs on the following reduced testcase when compiling w/
-floop-interchange at -O1, -O2, -O3, or -Ofast:

int ce[2];
int o5;
int p7;

int
main(void)
{
  int j1;
  ce[0] = 0;
  for (j1 = 0; j1 < 2; ++j1)
    for (o5 = 1; o5 >= 0; --o5)
      p7 += ce[o5];
  return 0;
}

% gcc-6.0.0-alpha20151122 -O2 -floop-interchange u21pw9kn.c
u21pw9kn.c: In function 'main':
u21pw9kn.c:6:1: internal compiler error: in copy_loop_phi_args, at sese.c:1133
 main(void)
 ^~~~

2. Additionally, it fails the same way on the testcase below w/
-floop-interchange -O1:

int du;

int
main(void)
{
  int u7[2];
  int ar;

  for (ar = 0; ar < 2; ++ar) {
    int xo;

    for (xo = 0; xo < 2; ++xo) {
      du += u7[ar];
      u7[0] = 0;
    }
  }

  return 0;
}

% gcc-6.0.0-alpha20151122 -O1 -floop-interchange da3mkq0z.c
da3mkq0z.c: In function 'main':
da3mkq0z.c:4:1: internal compiler error: in copy_loop_phi_args, at sese.c:1133
 main(void)
 ^~~~

3. 6.0.0-alpha20151122 also fails on both, but w/o verbose ICE description
(probably, due to refactoring performed in r230566 and r230567):

u21pw9kn.c: In function 'main':
u21pw9kn.c:6:1: internal compiler error: Segmentation fault
 main(void)
 ^~~~