public inbox for gcc-help@gcc.gnu.org
 help / color / mirror / Atom feed
From: Tim Prince <timothyprince@sbcglobal.net>
To: Deng Shi <Deng.Shi@synopsys.com>
Cc: gcc-help@gcc.gnu.org
Subject: Re: Inconsistent floating point result when using G++ 3.3.6 with  option -O0 or -O1 separately
Date: Fri, 14 Jul 2006 12:28:00 -0000	[thread overview]
Message-ID: <44B78DC8.2030005@sbcglobal.net> (raw)
In-Reply-To: <63E93BF3055BAC45A75523C731737ECBDFA187@JP01WEMBX1.internal.synopsys.com>

Deng Shi wrote:
>  
> 
> -----Original Message-----
> From: Deng Shi 
> Sent: 2006年7月13日 10:37
> To: 'gnu-help@gnu.org'
> Subject: Inconsistent floating point result when using G++ 3.3.6 with option -O0 or -O1 separately
> 
> hi expert,
> I found our application tool gave the inconsistent floating point result when using different optimization level -O0 or -O1.
> Even if I used -O1 plus all the disabling options which includes in -O1, like -O1 -fno-merge-all-constants -fno-zero-initialized-in-bss -fno-function-cse -fno-keep-static-consts -fno-omit-frame-pointer -fno-merge-constants -fno-loop-optimize -fno-cprop-registers -fno-if-conversion -fno-if-conversion2 -fno-delayed-branch -fno-guess-branch-probability -fno-defer-pop -fno-crossjumping -fno-thread-jumps " which command line setting should be equal to -O0, but I still didn't get the consistent result. 
> I wonder whether there is any additional optimization enabled by -O1 for C++ language which is not documented in GCC manual?
> 
If you're generating x87 code (the default for ia32), -ffloat-store 
would be among the first options normally tried to remove extra 
precision.  How are we to know what target you have, and which options 
you used?

  parent reply	other threads:[~2006-07-14 12:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-14  5:13 Deng Shi
2006-07-14  5:52 ` Ian Lance Taylor
2006-07-14 12:28 ` Tim Prince [this message]
2006-07-14  6:17 Deng Shi
2006-07-14  6:21 ` Ian Lance Taylor
2006-07-17  0:45 Deng Shi

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=44B78DC8.2030005@sbcglobal.net \
    --to=timothyprince@sbcglobal.net \
    --cc=Deng.Shi@synopsys.com \
    --cc=gcc-help@gcc.gnu.org \
    --cc=tprince@myrealbox.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).