public inbox for gcc-patches@gcc.gnu.org
 help / color / mirror / Atom feed
From: "Kewen.Lin" <linkw@linux.ibm.com>
To: Qing Zhao <qing.zhao@oracle.com>
Cc: gcc-patches Nick Alcock via <gcc-patches@gcc.gnu.org>,
	"H.J. Lu" <hjl.tools@gmail.com>
Subject: Re: Values of WIDE_INT_MAX_ELTS in gcc11 and gcc12 are different
Date: Fri, 5 Nov 2021 09:34:55 +0800	[thread overview]
Message-ID: <1e3c4b4d-596a-abd4-8d4a-b1a4ae6c6ba9@linux.ibm.com> (raw)
In-Reply-To: <7B702DE8-7B94-4317-BC19-610D2F406759@oracle.com>

Hi Qing,

on 2021/11/5 上午4:37, Qing Zhao via Gcc-patches wrote:
> Hi,
> 
> I noticed that the macro “WIDE_INT_MAX_ELTS” has different values in GCC11 and GCC12 (on the same X86 machine)
> 
> For gcc11:
> 
> wide int max elts =3
> 
> For gcc12:
> 
> wide int max elts =9
> 
> Does anyone know what’s the reason for this difference? 
> 

I guess it's due to commit r12-979 (782e57f2c09).

For

  #define WIDE_INT_MAX_ELTS \
    ((MAX_BITSIZE_MODE_ANY_INT + HOST_BITS_PER_WIDE_INT) / HOST_BITS_PER_WIDE_INT

Before the change, the MAX_BITSIZE_MODE_ANY_INT is explicitly set as 160.

  -#define MAX_BITSIZE_MODE_ANY_INT (160)

  it's (160+64)/64 = 3

After the change, MAX_BITSIZE_MODE_ANY_INT is counted in function emit_max_int
and becomes 512.

  it's (512+64)/64 = 9

As the commit log, the previous 160 bits seems a workaround for some gone
problem, now the commit makes it use the default way to align with the other
ports.

BR,
Kewen

> Thanks a lot for any help.
> 
> Qing
>

  reply	other threads:[~2021-11-05  1:35 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-04 20:37 Qing Zhao
2021-11-05  1:34 ` Kewen.Lin [this message]
2021-11-05  6:05 ` Andrew Pinski
2021-11-05  6:53   ` Jakub Jelinek
2021-11-05 10:01     ` Richard Biener
2021-11-05 12:25       ` H.J. Lu
2021-11-05 16:11       ` Qing Zhao
2021-11-05 16:17         ` Jakub Jelinek
2021-11-05 17:37           ` Qing Zhao
2021-11-06  9:56             ` Jakub Jelinek
2021-11-08  8:41               ` Richard Biener
2021-11-08 23:47                 ` Qing Zhao
2021-11-09  7:13                   ` Richard Biener
2021-11-09  9:10                     ` Jakub Jelinek
2021-11-09 10:44                       ` Richard Biener
2021-11-09 17:19                         ` Qing Zhao
2021-11-10  8:37                           ` Richard Biener
2021-11-10 18:02                             ` Qing Zhao

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1e3c4b4d-596a-abd4-8d4a-b1a4ae6c6ba9@linux.ibm.com \
    --to=linkw@linux.ibm.com \
    --cc=gcc-patches@gcc.gnu.org \
    --cc=hjl.tools@gmail.com \
    --cc=qing.zhao@oracle.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).