[Bug tree-optimization/53265] Warn when undefined behavior implies smaller iteration count

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53265

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-29 17:22:34 UTC ---
Other examples from
https://lists.fedoraproject.org/pipermail/devel/2013-January/175876.html
to test the potential warning (requires 32-bit integer and 64-bit long long):

void bar (void *);

void
fn1 (void)
{
  unsigned int a[128];
  int i;

  for (i = 0; i < 128; ++i)
    a[i] = i * 0x02000001;
  bar (a);
}

void
fn2 (void)
{
  unsigned long long a[128];
  int i;

  for (i = 0; i < 128; i++)
    a[i] = (i + 1LL) * 0x0123456789ABCDEFLL;
  bar (a);
}

void
fn3 (void)
{
  unsigned char a[16], b[16], c[16];
  int i;

  bar (b);
  for (i = 0; i < (int) (sizeof (a) / sizeof (a[0])); i++)
    {
      c[i + 8] = b[i];
      a[i + 8] = b[i + 8];
    }
  bar (a);
  bar (c);
}

void
fn4 (void)
{
  unsigned int *a[32], *o, i;

  bar (a);
  for (i = 0; i <= sizeof (a) / sizeof (a[0]); i++)
    {
      o = a[i];
      bar (o);
    }
}

void
fn5 (void)
{
  unsigned short a[23940];
  unsigned int b[1140];
  int j;

  bar (b);
  for (j = 0; j < 1140; j++)
    a[23940 + j - 950] = b[j];
  bar (a);
}