[Bug c/25487] New: Assertion failure in pointer analysis

["dps at simpson dot demon dot co dot uk" <gcc-bugzilla at gcc dot gnu dot org>]

The source here generates an asserion failure compiled with anything above -O0.
Changing p+1 to p seems to avoid the bug. The infinite loops are not a feature
of the original code but the uderlying problem appears to be indentical.

"screenshot"

dps@dps:~/duncan/src/foo/wlocal/build/phone/mq$ gcc --version
gcc (GCC) 4.2.0 20051217 (experimental)
Copyright (C) 2005 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

dps@dps:~/duncan/src/foo/wlocal/build/phone/mq$ gcc --version 
gcc (GCC) 4.2.0 20051217 (experimental)
Copyright (C) 2005 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

dps@dps:~/duncan/src/foo/wlocal/build/phone/mq$ gcc -g -O2 -o /tmp/foo.o
/tmp/foo.c
/tmp/foo.c: In function 'foo':
/tmp/foo.c:32: internal compiler error: in handle_ptr_arith, at
tree-ssa-structalias.c:3188
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

foo.c is the following nonsense
---cut here---
#include <stdio.h>

typedef struct
{
    int foo;
} s_foo;

static void bar(const s_foo *p,
                     int (*cmp)(const char *, const char *))
{
    const char *pd;
    int r;

    pd=(const char *) (p+1);    /* The p+1 is apparently critical */

    while (1)
    {
        r=(*cmp)(pd, "2");
        if (r<=0)
            fputc('-', stdout);
        else
            fputc('+', stdout);
    }
    return;
}

void foo(int (*cmp)(const char *, const char *))
{
    s_foo a;

    while(1)
    {
        bar(&a, cmp);
    }
}
---cut here---


-- 
           Summary: Assertion failure in pointer analysis
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dps at simpson dot demon dot co dot uk
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25487