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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/106514] [12/13 Regression] ranger slowness in
 path query
Date: Tue, 13 Dec 2022 14:02:17 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106514

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #10)
> Re-confirmed.  =3D15 vs =3D30 goes from
>=20
>  backwards jump threading           :   0.58 ( 13%)
>=20
> to
>=20
>  backwards jump threading           :   7.00 ( 65%)
>=20
> so it still shows exponential behavior for CFGs like
>=20
>  if (a)
>    ...
>  if (b)
>    ...
>  if (c)
>    ...
>=20
> because we explore all paths through the CFG that fit in some size limit.
> I'm not sure if there's any low hanging fruit besides this (like if we
> properly avoid re-doing local computes when visiting blocks as part of a
> path multiple times).

We do have --param max-jump-thread-paths putting a hard limit on the number
of branches in a paths we explore, the default might just be a bit high
for this testcase.=