Re: Optimisation code path for reading images
Juri Abramov <[email protected]> Tue, 18 Jun 2013 18:13:56 +0200
| Newsgroups | gmane.comp.video.openexr.devel,gmane.comp.video.openexr.user |
|---|---|
| Message-ID | <[email protected]> |
--===============5392222857843717484== Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_D3359C70CFE7484199E06844F5A2185E2723CBD838DEMAIL01nvidi_" --_000_D3359C70CFE7484199E06844F5A2185E2723CBD838DEMAIL01nvidi_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Halfdan, Yep, we ran into this one too. Was already the case for OpenEXR 1.6/1.7. Would be good to know if it is fixed in 4.5. Juri From: [email protected] [mailto:openex= [email protected]] On Behalf Of Halfdan Ingv= arsson Sent: 18 June, 2013 18:06 To: Piotr Stanczyk Cc: [email protected]; [email protected] Subject: Re: [Openexr-devel] Optimisation code path for reading images Also, compiling the EXR2.0 library using gcc 4.2/4.3/4.4 with -O3 results i= n the PIZ compression code producing occasional garbage data (-O3 is the de= fault 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. 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. 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 opti= mised reading code path which unfortunately revealed erroneous assumptions = in the source. We have a fix for handling these, which also extents to handling more gener= al cases, in a separate branch and will be releasing that once we have bui= lt up more usage cycles. In the meantime, however, a v2.0.1 release will be available shortly, which= disables the optimisation. - Piotr _______________________________________________ Openexr-devel mailing list [email protected]<mailto:[email protected]> https://lists.nongnu.org/mailman/listinfo/openexr-devel --_000_D3359C70CFE7484199E06844F5A2185E2723CBD838DEMAIL01nvidi_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; charset=3Diso-8859-= 1"> <html xmlns:v=3D"urn:schemas-microsoft-com:vml" xmlns:o=3D"urn:schemas-micr= osoft-com:office:office" xmlns:w=3D"urn:schemas-microsoft-com:office:word" = xmlns:m=3D"http://schemas.microsoft.com/office/2004/12/omml" xmlns=3D"http:= //www.w3.org/TR/REC-html40"><head><meta name=3DGenerator content=3D"Microso= ft Word 14 (filtered medium)"><style><!-- /* Font Definitions */ @font-face {font-family:PMingLiU; panose-1:2 2 5 0 0 0 0 0 0 0;} @font-face {font-family:PMingLiU; panose-1:2 2 5 0 0 0 0 0 0 0;} @font-face {font-family:Tahoma; panose-1:2 11 6 4 3 5 4 4 2 4;} @font-face {font-family:Verdana; panose-1:2 11 6 4 3 5 4 4 2 4;} @font-face {font-family:Consolas; panose-1:2 11 6 9 2 2 4 3 2 4;} @font-face {font-family:"\@PMingLiU"; panose-1:2 2 5 0 0 0 0 0 0 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0in; margin-bottom:.0001pt; font-size:12.0pt; font-family:"Times New Roman","serif"; color:black;} a:link, span.MsoHyperlink {mso-style-priority:99; color:blue; text-decoration:underline;} a:visited, span.MsoHyperlinkFollowed {mso-style-priority:99; color:purple; text-decoration:underline;} p {mso-style-priority:99; margin:0in; margin-bottom:.0001pt; font-size:12.0pt; font-family:"Times New Roman","serif"; color:black;} pre {mso-style-priority:99; mso-style-link:"HTML Preformatted Char"; margin:0in; margin-bottom:.0001pt; font-size:10.0pt; font-family:"Courier New"; color:black;} span.HTMLPreformattedChar {mso-style-name:"HTML Preformatted Char"; mso-style-priority:99; mso-style-link:"HTML Preformatted"; font-family:"Consolas","serif"; color:black;} span.EmailStyle20 {mso-style-type:personal-reply; font-family:"Verdana","sans-serif"; color:#17365D; font-weight:bold;} .MsoChpDefault {mso-style-type:export-only; font-size:10.0pt;} @page WordSection1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in;} div.WordSection1 {page:WordSection1;} --></style><!--[if gte mso 9]><xml> <o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" /> </xml><![endif]--><!--[if gte mso 9]><xml> <o:shapelayout v:ext=3D"edit"> <o:idmap v:ext=3D"edit" data=3D"1" /> </o:shapelayout></xml><![endif]--></head><body bgcolor=3Dwhite lang=3DEN-US= link=3Dblue vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal>= <b><span style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif";color= :#17365D'>Hi Halfdan,<o:p></o:p></span></b></p><p class=3DMsoNormal><b><spa= n style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif";color:#17365= D'><o:p> </o:p></span></b></p><p class=3DMsoNormal><b><span style=3D'f= ont-size:10.0pt;font-family:"Verdana","sans-serif";color:#17365D'>Yep, we r= an into this one too. Was already the case for OpenEXR 1.6/1.7.<o:p></o:p><= /span></b></p><p class=3DMsoNormal><b><span style=3D'font-size:10.0pt;font-= family:"Verdana","sans-serif";color:#17365D'>Would be good to know if it is= fixed in 4.5.<o:p></o:p></span></b></p><p class=3DMsoNormal><b><span style= =3D'font-size:10.0pt;font-family:"Verdana","sans-serif";color:#17365D'><o:p= > </o:p></span></b></p><p class=3DMsoNormal><b><span style=3D'font-siz= e:10.0pt;font-family:"Verdana","sans-serif";color:#17365D'>Juri<o:p></o:p><= /span></b></p><p class=3DMsoNormal><b><span style=3D'font-size:10.0pt;font-= family:"Verdana","sans-serif";color:#17365D'><o:p> </o:p></span></b></= p><div><div style=3D'border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0= pt 0in 0in 0in'><p class=3DMsoNormal><b><span style=3D'font-size:10.0pt;fon= t-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span styl= e=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> = [email protected] [mailto:openexr-deve= [email protected]] <b>On Behalf Of </b>Halfdan Ing= varsson<br><b>Sent:</b> 18 June, 2013 18:06<br><b>To:</b> Piotr Stanczyk<br= ><b>Cc:</b> [email protected]; [email protected]<br><b>Subject= :</b> Re: [Openexr-devel] Optimisation code path for reading images<o:p></o= :p></span></p></div></div><p class=3DMsoNormal><o:p> </o:p></p><div><p= class=3DMsoNormal>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 b= uild with -O2. gcc 4.6 and up seem ok. I didn't test with gcc 4.5.<br><br>U= nfortunately, I didn't have time to dig any deeper as to whether this was a= n actual optimizer bug, or whether there are some spurious assumptions in t= he code leading to it.<br><br>Just something to keep in mind.<br><br> = - =BD<br><br>On 13-06-17 09:35 PM, Piotr Stanczyk wrote:<o:p></o:p></p></di= v><blockquote style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><p class= =3DMsoNormal style=3D'margin-bottom:12.0pt'><span style=3D'font-size:10.0pt= ;font-family:"Tahoma","sans-serif"'><br>Hi, <br><br>There have been a few u= sage 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 gener= al cases, in a separate branch and will be releasing that once we hav= e built up more usage cycles. <br><br>In the meantime, however, a v2.0.1 re= lease will be available shortly, which disables the optimisation.<o:p></o:p= ></span></p><div><p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><span = style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'><o:p> </o= :p></span></p><div><p class=3DMsoNormal><span style=3D'font-size:10.0pt;fon= t-family:"Tahoma","sans-serif"'>- Piotr<o:p></o:p></span></p></div></div></= div><p class=3DMsoNormal><br><br><br><o:p></o:p></p><pre>__________________= _____________________________<o:p></o:p></pre><pre>Openexr-devel mailing li= st<o:p></o:p></pre><pre><a href=3D"mailto:[email protected]">Openexr= [email protected]</a><o:p></o:p></pre><pre><a href=3D"https://lists.nongnu.= org/mailman/listinfo/openexr-devel">https://lists.nongnu.org/mailman/listin= fo/openexr-devel</a><o:p></o:p></pre></blockquote><p class=3DMsoNormal><o:p= > </o:p></p></div></body></html>= --_000_D3359C70CFE7484199E06844F5A2185E2723CBD838DEMAIL01nvidi_-- --===============5392222857843717484== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Openexr-devel mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/openexr-devel --===============5392222857843717484==--