From: Jeff Law <law@redhat.com>
To: Richard Biener <rguenther@suse.de>, Jiufu Guo <guojiufu@linux.ibm.com>
Cc: gcc-patches@gcc.gnu.org, Jakub Jelinek <jakub@redhat.com>,
Daniel Berlin <dberlin@dberlin.org>,
segher@kernel.crashing.org, wschmidt@linux.ibm.com
Subject: Re: [PATCH] A jump threading opportunity for condition branch
Date: Wed, 29 May 2019 20:26:00 -0000 [thread overview]
Message-ID: <b808d487-365f-d5b3-5705-3ec493914665@redhat.com> (raw)
In-Reply-To: <alpine.LSU.2.20.1905241436310.10704@zhemvz.fhfr.qr>
On 5/24/19 6:45 AM, Richard Biener wrote:
[ Aggressive snipping ]
> As said in my first review I'd just check whether for the
> edge we want to thread through the definition comes from a CMP.
> Suppose you have
>
> # val_1 = PHI <a_2, b_3, c_4>
> if (val_1 != 0)
>
> and only one edge has a b_3 = d_5 != 0 condition it's still
> worth tail-duplicating the if block.
Agreed. The cost of tail duplicating here is so small we should be
doing it highly aggressively. About the only case where we might not
want to would be if we're optimizing for size rather than speed. That
case isn't clearly a win either way.
jeff
next prev parent reply other threads:[~2019-05-29 20:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 13:45 Jiufu Guo
2019-05-22 12:38 ` Richard Biener
2019-05-23 12:06 ` Jiufu Guo
2019-05-23 12:11 ` Richard Biener
2019-05-23 14:40 ` Jiufu Guo
2019-05-24 12:45 ` Richard Biener
2019-05-24 14:52 ` Jiufu Guo
2019-05-28 14:07 ` [PATCH V2] " Jiufu Guo
2019-05-29 1:51 ` Jiufu Guo
2019-05-29 12:40 ` Richard Biener
2019-05-29 19:47 ` Jeff Law
2019-05-30 15:09 ` Jiufu Guo
2019-05-30 23:55 ` Jeff Law
2019-05-31 7:34 ` Richard Biener
2019-06-04 3:03 ` Jiufu Guo
2019-05-30 15:34 ` Jeff Law
2019-06-03 2:18 ` [PATCH V3] " Jiufu Guo
2019-06-04 5:30 ` [PATCH V4] " Jiufu Guo
2019-06-13 18:56 ` Jeff Law
2019-06-14 12:51 ` Jiufu Guo
2019-06-14 16:34 ` Jeff Law
2019-05-29 20:26 ` Jeff Law [this message]
2019-05-30 6:57 ` [PATCH] " Richard Biener
2019-05-30 6:58 ` Jiufu Guo
2019-05-30 14:59 ` Jeff Law
2019-05-30 15:03 ` Jeff Law
2019-05-29 20:22 ` Jeff Law
2019-05-30 6:40 ` Jiufu Guo
2019-05-30 6:44 ` Richard Biener
2019-05-30 20:17 ` Jeff Law
2019-05-31 7:30 ` Richard Biener
2019-05-31 15:28 ` Jeff Law
2019-06-04 5:19 ` Jiufu Guo
2019-06-04 7:07 ` Richard Biener
2019-06-07 0:05 ` Jeff Law
2019-05-29 20:18 ` Jeff Law
2019-05-30 6:41 ` Richard Biener
2019-05-29 20:12 ` Jeff Law
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