From: Richard Sandiford <richard.sandiford@arm.com>
To: 钟居哲 <juzhe.zhong@rivai.ai>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>, rguenther <rguenther@suse.de>
Subject: Re: [PATCH V14] VECT: Add decrement IV iteration loop control by variable amount support
Date: Wed, 24 May 2023 17:00:58 +0100 [thread overview]
Message-ID: <mpt8rdden2d.fsf@arm.com> (raw)
In-Reply-To: <70D20B75C645F088+2023052423522166255038@rivai.ai> (=?utf-8?B?IumSn+WxheWTsiIncw==?= message of "Wed, 24 May 2023 23:52:22 +0800")
钟居哲 <juzhe.zhong@rivai.ai> writes:
> Oh. I see. Thank you so much for pointing this.
> Could you tell me what I should do in the codes?
> It seems that I should adjust it in
> vect_adjust_loop_lens_control
>
> muliply by some factor ? Is this correct multiply by max_nscalars_per_iter
> ?
max_nscalars_per_iter * factor rather than just max_nscalars_per_iter
Note that it's possible for later max_nscalars_per_iter * factor to
be smaller, so a division might be needed in rare cases. E.g.:
uint64_t x[100];
uint16_t y[200];
void f() {
for (int i = 0, j = 0; i < 100; i += 2, j += 4) {
x[i + 0] += 1;
x[i + 1] += 2;
y[j + 0] += 1;
y[j + 1] += 2;
y[j + 2] += 3;
y[j + 3] += 4;
}
}
where y has a single-control rgroup with max_nscalars_per_iter == 4
and x has a 2-control rgroup with max_nscalars_per_iter == 2
What gives the best code in these cases? Is emitting a multiplication
better? Or is using a new IV better?
Thanks,
Richard
next prev parent reply other threads:[~2023-05-24 16:01 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 [this message]
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
[not found] ` <2023052423130398041121@rivai.ai>
2023-05-24 15:31 ` 回复: " 钟居哲
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