Checking undefined_p before using the vr

Checking undefined_p before using the vr

For pattern "(X + C) / N": "div (plus@3 @0 INTEGER_CST@1) INTEGER_CST@2)",
Even if "X" has value-range and "X + C" does not overflow, "@3" may still
be undefined. Like below example:

_3 = _2 + -5;
if (0 != 0)
  goto <bb 3>; [34.00%]
else
  goto <bb 4>; [66.00%]
;;  succ:       3
;;              4

;; basic block 3, loop depth 0
;;  pred:       2
_5 = _3 / 5;
;;  succ:       4

The whole pattern "(_2 + -5 ) / 5" is in "bb 3", but "bb 3" would be
unreachable (because "if (0 != 0)" is always false).
And "get_range_query (cfun)->range_of_expr (vr3, @3)" is checked in
"bb 3", "range_of_expr" gets an "undefined vr3". Where "@3" is "_5".

So, before using "vr3", it would be safe to check "!vr3.undefined_p ()".

	PR tree-optimization/111303

gcc/ChangeLog:

	* match.pd ((X - N * M) / N): Add undefined_p checking.
	((X + N * M) / N): Likewise.
	((X + C) div_rshift N): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr111303.c: New test.