[Bug middle-end/41463] New: Another get_ref_base_and_extent problem

[jamborm at gcc dot gnu dot org]

The testcase below aborts when compiled with -O2.  

------------------------------------------------------------
union tree_node;


struct tree_common 
{
  int a;
  long b;
  long c;
  void *p;
  int d;
};

struct other_tree
{
  struct tree_common common;
  int arr[14];
};

struct tree_vec
{
  struct tree_common common;
  int length;
  union tree_node *a[1];
};

union tree_node
{
  struct other_tree othr;
  struct tree_vec vec;
};

union tree_node global;

union tree_node * __attribute__((noinline))
foo (union tree_node *p, int i)
{
  union tree_node **q;
  p->vec.a[i] = (union tree_node *) 0;
  q = &p->vec.a[1];
  *q = &global;
  return p->vec.a[i];
}

extern void abort (void);
extern void *malloc (__SIZE_TYPE__);

int
main()
{
  union tree_node *p = malloc (sizeof (union tree_node));
  if (foo (p, 1) != &global)
    abort ();
  return 0;
}
------------------------------------------------------------

foo() is optimized to return NULL, most probably because
get_ref_base_and_extent does not recognize that accesses to a do not
necessarily have to have constant max_size.

I have tried with trunk revision 152041 and 152147.  The latter
specifically is:

jamb...@gcc16:~/gcc/test$ ~/gcc/inst/trunk/bin/gcc -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /home/jamborm/gcc/trunk/configure
--prefix=/home/jamborm/gcc/inst/trunk/ --enable-checking=release
--enable-languages=c,c++ --disable-bootstrap --with-mpfr=/opt/cfarm/mpfr-2.3.2/
--disable-multilib
Thread model: posix
gcc version 4.5.0 20090924 (experimental) (GCC)


-- 
           Summary: Another get_ref_base_and_extent problem
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jamborm at gcc dot gnu dot org
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41463