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From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/106075] Wrong DSE with -fnon-call-exceptions
Date: Mon, 08 May 2023 13:25:49 +0000 [thread overview]
Message-ID: <bug-106075-4-D79u8uQFzw@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-106075-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106075
--- Comment #11 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> Eric, maybe you can help with RTL DSE here?
The problem is that add_non_frame_wild_read is exclusive, i.e. the read is
turned into a read from *only* non-frame memory, but can_throw_external
is conservative and may return true for a read from frame memory:
(insn 15 13 16 4 (set (reg:QI 87 [ _20 ])
(mem:QI (plus:DI (reg/f:DI 100)
(reg:DI 92 [ ivtmp.23 ])) [8 MEM <character>
[(interfaces__unsigned_32 *)&value.4 + ivtmp.23_39 * 1]+0 S1 A8]))
"opt47.adb":22:13 91 {*movqi_internal}
value.4 is a local variable but can_throw_external return true on the read.
So you would need to implement an inclusive version of add_non_frame_wild_read
but the change is going to pessimize Ada and Go if the condition to invoke it
is not made more precise.
next prev parent reply other threads:[~2023-05-08 13:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 9:34 [Bug middle-end/106075] New: " hubicka at gcc dot gnu.org
2022-06-24 9:36 ` [Bug middle-end/106075] " pinskia at gcc dot gnu.org
2022-06-24 9:39 ` pinskia at gcc dot gnu.org
2022-06-24 10:39 ` rguenth at gcc dot gnu.org
2022-06-24 11:14 ` hubicka at gcc dot gnu.org
2022-06-24 11:15 ` hubicka at gcc dot gnu.org
2023-01-16 20:58 ` hubicka at gcc dot gnu.org
2023-01-17 9:16 ` rguenth at gcc dot gnu.org
2023-05-03 12:56 ` rguenth at gcc dot gnu.org
2023-05-03 12:57 ` rguenth at gcc dot gnu.org
2023-05-08 9:35 ` ebotcazou at gcc dot gnu.org
2023-05-08 13:25 ` ebotcazou at gcc dot gnu.org [this message]
2023-05-08 13:49 ` rguenther at suse dot de
2023-05-08 13:54 ` rguenth at gcc dot gnu.org
2023-05-08 13:55 ` ebotcazou at gcc dot gnu.org
2023-05-08 13:57 ` ebotcazou at gcc dot gnu.org
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