[Bug tree-optimization/59359] New: Segmentation fault in thread_through_all_blocks

[antoine.balestrat at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59359

            Bug ID: 59359
           Summary: Segmentation fault in thread_through_all_blocks
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: antoine.balestrat at gmail dot com

Hello !
The following testcase makes GCC 4.9.0 as of 20131201 crash.

$ cat seg.c
int a, b;

void f()
{
    int c = 0;

    for(; b; b++)
    {
        for(a = 0; a; a++);

        unsigned d = 1;

        for(; c < 2; c++)
            if(d = (c = d) < 1)
                return;
    }
}

$ xgcc -O2 -w seg.c
seg.c: In function ‘f’:
seg.c:3:6: internal compiler error: Segmentation fault
 void f()
      ^
0x9901cf crash_signal
        ../../srcdir/gcc/toplev.c:336
0xb33a67 thread_through_all_blocks(bool)
        ../../srcdir/gcc/tree-ssa-threadupdate.c:1652
0xa7a7ab tree_ssa_dominator_optimize
        ../../srcdir/gcc/tree-ssa-dom.c:886
0xa7a7ab execute
        ../../srcdir/gcc/tree-ssa-dom.c:984
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.