[Bug middle-end/55011] New: GCC in an infinite loop at -O2

["antoine.balestrat at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55011

             Bug #: 55011
           Summary: GCC in an infinite loop at -O2
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: antoine.balestrat@gmail.com


GCC 4.8.0 as of 20121021 seems to be stuck in an infinite loop while compiling
the following testcase at -O2 (works at -O1 and -O3) :

$ cat infloop.c
char a;

void f(void)
{
    char b = 2;

    for(;;)
    {
        unsigned short s = 1, *p = &s, *i;

        for(*i = 0; *i < 4; ++*i)
            if(a | (*p /= (b += !!a)) <= 63739)
                return;

        if(!s)
            a = 0;

        for(;;);
    }
}

$ ulimit -t 120

$ xgcc -O2 infloop.c

... 2 minutes later :

gcc: internal compiler error: CPU time limit exceeded (program cc1)
linux-vdso.so.1: No such file or directory
0x40b937 execute
    ../../srcdir/gcc/gcc.c:2739
0x40c7be do_spec_1
    ../../srcdir/gcc/gcc.c:4534
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
0x40d397 do_spec_1
    ../../srcdir/gcc/gcc.c:5179
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
0x40d397 do_spec_1
    ../../srcdir/gcc/gcc.c:5179
0x40cff7 do_spec_1
    ../../srcdir/gcc/gcc.c:5284
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
0x40d397 do_spec_1
    ../../srcdir/gcc/gcc.c:5179
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
0x40d397 do_spec_1
    ../../srcdir/gcc/gcc.c:5179
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
0x40d397 do_spec_1
    ../../srcdir/gcc/gcc.c:5179
0x40f0d5 process_brace_body
    ../../srcdir/gcc/gcc.c:5782
0x40f0d5 handle_braces
    ../../srcdir/gcc/gcc.c:5696
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.

Please let me know if you need more information !