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From: "guojiufu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/63281] powerpc64le creates 64 bit constants from scratch instead of loading them
Date: Tue, 04 Jan 2022 06:07:21 +0000	[thread overview]
Message-ID: <bug-63281-4-rj3yQkRZ32@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-63281-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63281

--- Comment #19 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
(In reply to Segher Boessenkool from comment #18)
Thanks for your clarify! 
> Yes, it is slow.  Five sequential dependent integer instructions instead of
> one load instruction.  Depending on how you benchmark this you possibly won't
Yes, it depends on how the cases are benchmarked.  There are some factors that
affect the runtime.  This is really the point! 
In the above cases, a few std(s) and there is one spill on r31 are all affect
the runtime and would hide the instructions on const building.
Focusing on the sequence to build a const, the 5 insns sequence is faster a lot
than the sequence of 1 insns.

  parent reply	other threads:[~2022-01-04  6:07 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-16 23:01 [Bug target/63281] New: " anton at samba dot org
2014-09-17  6:32 ` [Bug target/63281] " amodra at gmail dot com
2014-09-17  6:40 ` amodra at gmail dot com
2021-12-21  9:23 ` [Bug rtl-optimization/63281] " guojiufu at gcc dot gnu.org
2021-12-21 11:09 ` guojiufu at gcc dot gnu.org
2021-12-21 14:29 ` segher at gcc dot gnu.org
2021-12-21 14:36 ` segher at gcc dot gnu.org
2021-12-30  3:29 ` guojiufu at gcc dot gnu.org
2021-12-30  7:14 ` amodra at gmail dot com
2021-12-31  1:51 ` guojiufu at gcc dot gnu.org
2021-12-31  2:00 ` guojiufu at gcc dot gnu.org
2021-12-31  7:33 ` segher at gcc dot gnu.org
2022-01-04  6:07 ` guojiufu at gcc dot gnu.org [this message]
2022-01-04  8:06 ` guojiufu at gcc dot gnu.org
2022-01-06 10:06 ` guojiufu at gcc dot gnu.org
2022-01-10  6:52 ` guojiufu at gcc dot gnu.org

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