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From: HAO CHEN GUI <guihaoc@linux.ibm.com>
To: Richard Biener <richard.guenther@gmail.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>, David <dje.gcc@gmail.com>,
	Peter Bergner <bergner@linux.ibm.com>,
	"Kewen.Lin" <linkw@linux.ibm.com>,
	Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: Ping [PATCH] Change the behavior of predicate check failure on cbranchcc4 operand0 in prepare_cmp_insn
Date: Tue, 29 Nov 2022 09:15:32 +0800	[thread overview]
Message-ID: <2e763337-f343-b08d-0866-b8edc9908f7e@linux.ibm.com> (raw)
In-Reply-To: <CAFiYyc18tY-0iV9=nZxoLmahK7gEGHqt1Ki0qws+m9sBhtwyVA@mail.gmail.com>

Hi Richard,

在 2022/11/29 2:46, Richard Biener 写道:
> Anyhow - my question still stands - what's the fallback for the callers
> that do not check for failure?  How are we sure we're not running into
> these when relaxing the requirement that a MODE_CC prepare_cmp_insn
> must not fail?

I examed the code and found that currently callers should be fine with
returning a NULL_RTX for MODE_CC processing. The prepare_cmp_insn is called
by following callers.

1 gen_cond_trap which doesn't uses MODE_CC
2 prepare_cmp_insn itself where is after MODE_CC processing, so it never
hits MODE_CC
3 emit_cmp_and_jump_insns which doesn't uses MODE_CC
4 emit_conditional_move which checks the output is null or not
5 emit_conditional_add which checks the output is null or not

Not sure if I missed something. Looking forward to your advice.

Thanks a lot
Gui Haochen


  parent reply	other threads:[~2022-11-29  1:15 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-23  2:54 HAO CHEN GUI
2022-11-28  5:32 ` Ping " HAO CHEN GUI
2022-11-28  8:42   ` Richard Biener
2022-11-28 17:56     ` Segher Boessenkool
2022-11-28 18:46       ` Richard Biener
2022-11-28 23:02         ` Segher Boessenkool
2022-11-29  1:15         ` HAO CHEN GUI [this message]
2022-11-29  8:26           ` Richard Biener
2022-11-28  6:16 ` Kewen.Lin

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