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From: "juzhe.zhong at rivai dot ai" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111760] risc-v regression: COND_LEN_* incorrect fold/simplify in middle-end
Date: Tue, 10 Oct 2023 22:08:33 +0000 [thread overview]
Message-ID: <bug-111760-4-IckuvVUwJQ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-111760-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111760
--- Comment #5 from JuzheZhong <juzhe.zhong at rivai dot ai> ---
(In reply to Robin Dapp from comment #2)
> https://gcc.gnu.org/pipermail/gcc-patches/2023-September/629904.html
>
> prevents the wrong code but still leaves us with a redundant negation (and
> it is not the only missed optimization of that kind):
>
> vect_neg_xi_14.4_23 = -vect_xi_13.3_22;
> vect_res_2.5_24 = .COND_LEN_ADD ({ -1, ... }, vect_res_1.0_17,
> vect_neg_xi_14.4_23, vect_res_1.0_17, _29, 0);
>
> That's because my "hackaround" doesn't recognize a valueized sequence
> _30 = vect_res_1.0_17 - vect_xi_13.3_22;
>
> Of course I could (reverse valueize) recognize that again and convert it to
> a COND_LEN... but that doesn't seem elegant at all. There must be a simpler
> way that I'm missing entirely right now. That said, converting the last
> statement of such a sequence should be sufficient?
Yeah. That's what I want to point it out. Your patch will disable the
optimization
I made in GIMPLE_FOLD for COND_LEN_xxx.
I am not sure how to fix it, I think we need Richi's help for that since he
knows
the GIMPLE FOLD stuff the best.
next prev parent reply other threads:[~2023-10-10 22:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-10 14:29 [Bug c/111760] New: " juzhe.zhong at rivai dot ai
2023-10-10 17:47 ` [Bug c/111760] " pinskia at gcc dot gnu.org
2023-10-10 21:02 ` [Bug tree-optimization/111760] " rdapp at gcc dot gnu.org
2023-10-10 21:58 ` juzhe.zhong at rivai dot ai
2023-10-10 22:04 ` pinskia at gcc dot gnu.org
2023-10-10 22:08 ` juzhe.zhong at rivai dot ai [this message]
2023-10-11 6:47 ` rdapp at gcc dot gnu.org
2023-10-11 8:36 ` rguenth at gcc dot gnu.org
2023-11-06 11:27 ` cvs-commit at gcc dot gnu.org
2023-11-07 23:39 ` juzhe.zhong at rivai dot ai
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