vrp: Improve register_edge_assert_for [PR95757]

vrp: Improve register_edge_assert_for [PR95757]

The Wstringop-overflow-25.c testcase doesn't emit one of the expected
warnings on targets that don't do short curcuiting due to target costs
(or e.g. with --param=logical-op-non-short-circuit=0 on all targets).

The problem is that only reassoc2 optimizes:
  _49 ={v} unsigned_value_source;
  if (_49 == 0)
    goto <bb 7>; [50.00%]
  else
    goto <bb 5>; [50.00%]

  <bb 5> [local count: 536870913]:
  if (_49 > 2)
    goto <bb 7>; [50.00%]
  else
    goto <bb 6>; [50.00%]

  <bb 6> [local count: 268435457]:
  _53 = _49 + 1;
into:
  _49 ={v} unsigned_value_source;
  _48 = _49 + 18446744073709551615;
  _1 = _48 > 1;
  if (_1 != 0)
    goto <bb 6>; [50.00%]
  else
    goto <bb 5>; [50.00%]

  <bb 5> [local count: 268435457]:
  _53 = _49 + 1;
(but, note the _1 = _48 > 1; if (_1 != 0)),
then dom3 is run and because of that if (_1 != 0) vs. if (_48 > 1) doesn't
register edge asserts for _48 and _49) and so we don't get
SSA_NAME_RANGE_INFO for _53 (and ditto for vrp2) and only afterwards comes
forwprop4 that canonicalizes it to if (_48 > 1).  While with
--param=logical-op-non-short-circuit=1 it is already reassoc1 that optimizes
it and forwprop3 that propagates it, so we have on the SSA_NAME
corresponding to _53 above SSA_NAME_RANGE_INFO and during expansion we warn.

The following patch fixes it by handling those not yet propagated
comparisons into GIMPLE_COND in register_edge_assert_for.  We already
have all the infrastructure there to handle the --param=logical-op-non-short-circuit=1
| and &s.

2021-03-02  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/95757
	* tree-vrp.c (register_edge_assert_for): Remove superfluous ()s around
	condition.  Call register_edge_assert_for_1 for == 0, != 0, == 1 and
	!= 1 comparisons if name is lhs of a comparison.