From: "juzhe.zhong@rivai.ai" <juzhe.zhong@rivai.ai>
To: richard.sandiford <richard.sandiford@arm.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>, rguenther <rguenther@suse.de>
Subject: Re: Re: [PATCH V14] VECT: Add decrement IV iteration loop control by variable amount support
Date: Thu, 25 May 2023 11:05:33 +0800 [thread overview]
Message-ID: <9BA82A9501B7D08D+20230525110533020956240@rivai.ai> (raw)
In-Reply-To: <mpto7m9cx76.fsf@arm.com>
[-- Attachment #1: Type: text/plain, Size: 1505 bytes --]
Hi, Richard.
After several tries with your testcases (I already added into V15 patch).
I think "using a new IV" would be better than "multiplication"
Now:
loop_len_34 = MIN_EXPR <ivtmp_72, 8>;
_74 = MIN_EXPR <ivtmp_75, 16>; ------> multiplication approach will changed into _74 = loop_len_34 * 2;
loop_len_48 = MIN_EXPR <_74, 4>;
_77 = _74 - loop_len_48;
loop_len_49 = MIN_EXPR <_77, 4>;
_78 = _77 - loop_len_49;
loop_len_50 = MIN_EXPR <_78, 4>;
loop_len_51 = _78 - loop_len_50;
I prefer "new IV" since it looks more reasonable and better codegen.
Could you take a look at it:
V15 patch:
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/619534.html
Thanks.
juzhe.zhong@rivai.ai
From: Richard Sandiford
Date: 2023-05-25 04:05
To: 钟居哲
CC: gcc-patches; rguenther
Subject: Re: [PATCH V14] VECT: Add decrement IV iteration loop control by variable amount support
I'll look at the samples tomorrow, but just to address one thing:
钟居哲 <juzhe.zhong@rivai.ai> writes:
>>> What gives the best code in these cases? Is emitting a multiplication
>>> better? Or is using a new IV better?
> Could you give me more detail information about "new refresh IV" approach.
> I'd like to try that.
By “using a new IV” I meant calling vect_set_loop_controls_directly
for every rgroup, not just the first. So in the earlier example,
there would be one decrementing IV for x and one decrementing IV for y.
Thanks,
Richard
next prev parent reply other threads:[~2023-05-25 3:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-24 14:48 juzhe.zhong
2023-05-24 15:07 ` Richard Sandiford
2023-05-24 15:13 ` 钟居哲
2023-05-24 15:31 ` Richard Sandiford
2023-05-24 15:42 ` 钟居哲
2023-05-24 15:47 ` Richard Sandiford
2023-05-24 15:52 ` 钟居哲
2023-05-24 16:00 ` Richard Sandiford
2023-05-24 16:15 ` 钟居哲
2023-05-24 16:37 ` 钟居哲
2023-05-24 20:05 ` Richard Sandiford
2023-05-25 3:05 ` juzhe.zhong [this message]
[not found] ` <2023052423130398041121@rivai.ai>
2023-05-24 15:31 ` 回复: " 钟居哲
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