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From: "randolph at tausq dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/17264] [hppa] Missing address increment optimization for fp load/stores
Date: Sun, 24 Sep 2006 23:48:00 -0000 [thread overview]
Message-ID: <20060924234811.26582.qmail@sourceware.org> (raw)
In-Reply-To: <bug-17264-581@http.gcc.gnu.org/bugzilla/>
------- Comment #3 from randolph at tausq dot org 2006-09-24 23:48 -------
Subject: Re: [hppa] Missing address increment
optimization for fp load/stores
>> gcc starting from 4.0 produces this:
>>
>> .L3:
>> fldds -16(%r26),%fr22
>> fldds -8(%r26),%fr23
>> fldds 0(%r26),%fr24
>> fldds 8(%r26),%fr25
>> ldo 32(%r26),%r26
>> fstds %fr22,-16(%r25)
>> fstds %fr23,-8(%r25)
>> fstds %fr24,0(%r25)
>> fstds %fr25,8(%r25)
>> b .L3
>>
>> which I suspect is actually better, since it avoids dependencies between the
>> loads. But I'm not familiar with hppa, can anybody comment?
>
> It looks close to optimal to me. The code is better than that generated
> by 3.4.x or HP cc. Using the auto-increment forms would allow elimination
> of the two ldo instructions to increment r25 and r26.
Yeah, this looks pretty good. I've been told that not using the
autoincrement forms might be even better as it avoids interlocks between
successive instructions. The ldo insn just gets pipelined so it doesn't
necessarily slow things down.
I'll mark this bug as resolved.
thanks
randolph
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17264
next prev parent reply other threads:[~2006-09-24 23:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-17264-581@http.gcc.gnu.org/bugzilla/>
2006-09-24 19:52 ` falk at debian dot org
2006-09-24 22:15 ` dave at hiauly1 dot hia dot nrc dot ca
2006-09-24 23:48 ` randolph at tausq dot org [this message]
2006-09-24 23:49 ` tausq at debian dot org
2004-09-01 18:22 [Bug rtl-optimization/17264] New: " tausq at debian dot org
2004-09-01 18:53 ` [Bug rtl-optimization/17264] " danglin at gcc dot gnu dot org
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