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From: "guojiufu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/111303] ICE: in type, at value-range.h:869
Date: Wed, 06 Sep 2023 12:47:28 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111303

--- Comment #4 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
For the pattern: "(X + C) / N", "op (plus@3 @0 INTEGER_CST@1) INTEGER_CST@2=
)"
where "X" has value-range, and "X + C" does not overflow:

&& get_range_query (cfun)->range_of_expr (vr0, @0))
&& get_range_query (cfun)->range_of_expr (vr1, @1)
&& range_op_handler (PLUS_EXPR).overflow_free_p (vr0, vr1)

Then "@3"(it is X+C) would be with value-range usually.
But for particular cases, like this PR, "vr3" is undefined.=20
Below would be the reason for why "vr3" is undefined:


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

;; basic block 3, loop depth 0
;;  pred:       2
_5 =3D _3 / 5;=20
;;  succ:       4

The whole pattern "(_2 + -5 ) / 5" is in "bb 3", but "bb" would be unreacha=
ble
(because "if (0 !=3D 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".=