public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "law at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/42652] vectorizer created unaligned vector insns
Date: Thu, 14 Jan 2010 17:30:00 -0000	[thread overview]
Message-ID: <20100114172948.22508.qmail@sourceware.org> (raw)
In-Reply-To: <bug-42652-391@http.gcc.gnu.org/bugzilla/>



------- Comment #11 from law at redhat dot com  2010-01-14 17:29 -------
Subject: Re:  vectorizer created unaligned vector
 insns

On 01/13/10 02:35, irar at il dot ibm dot com wrote:
> ------- Comment #10 from irar at il dot ibm dot com  2010-01-13 09:35 -------
> Yes, I understand that we can't assume that an access is aligned if we can't
> prove it's aligned. I don't understand how we can prove that a COMPONENT_REF is
> aligned, i.e., if there is a way to check if a struct is packed, or we'd better
> decide that we always use versioning for COMPONENT_REFs?
>    
Given a raw COMPONENT_REF I don't think you can prove proper alignment.  
You have to look at the entire effective address computation.  
Unfortunately, I think this has rather significant implications on how 
often we can vectorize without needing to perform the runtime check for 
alignment.

Jeff


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42652


  parent reply	other threads:[~2010-01-14 17:30 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-07 17:32 [Bug tree-optimization/42652] New: " law at redhat dot com
2010-01-07 17:33 ` [Bug tree-optimization/42652] " law at redhat dot com
2010-01-08 11:59 ` rguenth at gcc dot gnu dot org
2010-01-08 16:45 ` law at redhat dot com
2010-01-08 17:25 ` rguenth at gcc dot gnu dot org
2010-01-10  8:23 ` irar at il dot ibm dot com
2010-01-11 17:14 ` law at redhat dot com
2010-01-11 17:16 ` law at redhat dot com
2010-01-12  8:08 ` irar at il dot ibm dot com
2010-01-12 15:19 ` law at redhat dot com
2010-01-13  9:36 ` irar at il dot ibm dot com
2010-01-14 17:30 ` law at redhat dot com [this message]
2010-01-14 17:35 ` hjl dot tools at gmail dot com
2010-01-18 12:17 ` irar at il dot ibm dot com
2010-02-09 23:04 ` law at redhat dot com
2010-02-09 23:12 ` rguenth at gcc dot gnu dot org
2010-02-09 23:49 ` law at redhat dot com
2010-02-22  9:01 ` irar at il dot ibm dot com
2010-02-22 10:27 ` rguenth at gcc dot gnu dot org
     [not found] <bug-42652-4@http.gcc.gnu.org/bugzilla/>
2012-07-19 11:38 ` rguenth at gcc dot gnu.org

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=20100114172948.22508.qmail@sourceware.org \
    --to=gcc-bugzilla@gcc.gnu.org \
    --cc=gcc-bugs@gcc.gnu.org \
    /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).