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From: Robin Dapp <rdapp@linux.ibm.com>
To: Jeff Law <jeffreyalaw@gmail.com>,
	gcc-patches@gcc.gnu.org, richard.sandiford@arm.com
Subject: Re: [PATCH v3 4/7] ifcvt/optabs: Allow using a CC comparison for emit_conditional_move.
Date: Thu, 9 Dec 2021 18:20:43 +0100	[thread overview]
Message-ID: <4c00d2b4-a1b5-006f-3ca9-9613f3afc26b@linux.ibm.com> (raw)
In-Reply-To: <f95decd8-cd9a-66bd-b698-629dd2d430b2@gmail.com>

Hi Jeff,

thanks for looking into this.

> What if the condition has a side effect?  Doesn't this drop the side 
> effect by converting the conditional move into a simple move?
Hmm, good point, if the condition does more than a CC compare, it might
get tricky as we are not canonicalizing here (on purpose). Is there an
easy way out like checking something like side_effects_p ()?

Maybe we should drop this altogether and let the backend deal with it?
It would probably not know what to do and FAIL.

Regards
 Robin

  reply	other threads:[~2021-12-09 17:20 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-06 18:43 [PATCH v3 0/7] ifcvt: Convert multiple Robin Dapp
2021-12-06 18:43 ` [PATCH v3 1/7] ifcvt: Check if cmovs are needed Robin Dapp
2021-12-09  1:26   ` Jeff Law
2022-01-10 11:17     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 2/7] ifcvt: Allow constants for noce_convert_multiple Robin Dapp
2021-12-08 23:51   ` Jeff Law
2022-01-10 11:17     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 3/7] ifcvt: Improve costs handling " Robin Dapp
2021-12-08 23:54   ` Jeff Law
2022-01-10 11:17     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 4/7] ifcvt/optabs: Allow using a CC comparison for emit_conditional_move Robin Dapp
2021-12-09  0:11   ` Jeff Law
2021-12-09 17:20     ` Robin Dapp [this message]
2021-12-09 17:34       ` Jeff Law
2022-01-10 11:18     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 5/7] ifcvt: Try re-using CC for conditional moves Robin Dapp
2021-12-09  1:18   ` Jeff Law
2022-01-10 11:18     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 6/7] testsuite/s390: Add tests for noce_convert_multiple Robin Dapp
2021-12-08 23:48   ` Jeff Law
2022-01-10 11:18     ` Robin Dapp
2021-12-06 18:43 ` [PATCH v3 7/7] ifcvt: Run second pass if it is possible to omit a temporary Robin Dapp
2021-12-09  1:24   ` Jeff Law
2021-12-10 15:06     ` Robin Dapp
2021-12-15 20:24       ` Jeff Law
2022-01-10 11:18     ` Robin Dapp

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