Re: Optimisation code path for reading images

Halfdan Ingvarsson <[email protected]> Tue, 18 Jun 2013 12:06:28 -0400
Newsgroups gmane.comp.video.openexr.devel,gmane.comp.video.openexr.user
Message-ID <[email protected]> 
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Also, compiling the EXR2.0 library using gcc 4.2/4.3/4.4 with -O3=20
results in the PIZ compression code producing occasional garbage data=20
(-O3 is the default for cmake release builds). The workaround was to=20
build with -O2. gcc 4.6 and up seem ok. I didn't test with gcc 4.5.

Unfortunately, I didn't have time to dig any deeper as to whether this=20
was an actual optimizer bug, or whether there are some spurious=20
assumptions in the code leading to it.

Just something to keep in mind.

  - =BD

On 13-06-17 09:35 PM, Piotr Stanczyk wrote:
>
> Hi,
>
> There have been a few usage cases reported that exercised parts of the=20
> optimised reading code path which unfortunately revealed erroneous=20
> assumptions in the source.
>
> We have a fix for handling these, which also extents to handling more=20
> general cases,  in a separate branch and will be releasing that once=20
> we have built up more usage cycles.
>
> In the meantime, however, a v2.0.1 release will be available shortly,=20
> which disables the optimisation.
>
>
>
> - Piotr
>
>
> _______________________________________________
> Openexr-devel mailing list
> [email protected]
> https://lists.nongnu.org/mailman/listinfo/openexr-devel


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    <div class="moz-cite-prefix">Also, compiling the EXR2.0 library
      using gcc 4.2/4.3/4.4 with -O3 results in the PIZ compression code
      producing occasional garbage data (-O3 is the default for cmake
      release builds). The workaround was to build with -O2. gcc 4.6 and
      up seem ok. I didn't test with gcc 4.5.<br>
      <br>
      Unfortunately, I didn't have time to dig any deeper as to whether
      this was an actual optimizer bug, or whether there are some
      spurious assumptions in the code leading to it.<br>
      <br>
      Just something to keep in mind.<br>
      <br>
      &nbsp;- &frac12;<br>
      <br>
      On 13-06-17 09:35 PM, Piotr Stanczyk wrote:<br>
    </div>
    <blockquote
cite="mid:95F01873F66DA54DAD2734EEBF98F86C0110925321@mailbox09.lucas.alllucas.com"
      type="cite">
      <meta http-equiv="Content-Type" content="text/html;
        charset=ISO-8859-1">
      <style id="owaParaStyle" type="text/css">P {margin-top:0;margin-bottom:0;}</style>
      <div style="direction: ltr;font-family: Tahoma;color:
        #000000;font-size: 10pt;"><font size="2" face="Tahoma"
          color="black"><span style="font-size: 10pt;" dir="ltr"><br>
            Hi, <br>
            <br>
            There have been a few usage cases reported that exercised
            parts of the optimised reading code path which unfortunately
            revealed erroneous assumptions in the source.
            <br>
            <br>
            We have a fix for handling these, which also extents to
            handling more general cases,&nbsp; in a separate branch and will
            be releasing that once we have built up more usage cycles.
            <br>
            <br>
            In the meantime, however, a v2.0.1 release will be available
            shortly, which disables the optimisation.<br>
            <br>
            <div><br>
              <br>
              <div><font size="1"><span style="font-size: 13px;">- Piotr</span></font></div>
            </div>
          </span></font></div>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">_______________________________________________
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</pre>
    </blockquote>
    <br>
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