[Bug tree-optimization/103168] Value numbering for PRE of pure functions can be improved

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103168

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
And interestingly for

unsigned p;
unsigned __attribute__((noinline)) test (void)
{
  return p;
}

I do not get any modref summary!?

;; Function test (test, funcdef_no=0, decl_uid=1979, cgraph_uid=1,
symbol_order=1)

modref analyzing 'test' (ipa=0) (pure)
 - Analyzing load: p
   - Recording base_set=0 ref_set=0
 - modref done with result: tracked.
__attribute__((noinline))
unsigned int test ()
{
  unsigned int _2;

  <bb 2> [local count: 1073741824]:
  _2 = p;
  return _2;

}