<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
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;}
span.EmailStyle18
{mso-style-type:personal;
font-family:"Arial",sans-serif;
color:#44546A;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Arial",sans-serif;
color:#44546A;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
.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="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">Hal,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">No, it is not more of a problem than with DWARF info. DWARF info definitely contains personally identifiable information. However, people usually realize that
is the case,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">and will turn off or strip debug info if they are worried about such issues, or make a specific plan to cleanse that information.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">You really just want to attempt to eliminate such information to the greatest extent possible. The desirability of using embedded Bitcode in libraries (which is
a very<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">natural use model, that I'm pretty sure this is intended to support), will be improved by taking into consideration this aspect of the implementation.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">Kevin Smith<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"><o:p> </o:p></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><a name="_____replyseparator"></a><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Hal Finkel [mailto:hfinkel@anl.gov]
<br>
<b>Sent:</b> Saturday, February 06, 2016 2:37 PM<br>
<b>To:</b> Smith, Kevin B <kevin.b.smith@intel.com><br>
<b>Cc:</b> llvm-dev@lists.llvm.org; Clang Dev <cfe-dev@lists.llvm.org>; James Y Knight <jyknight@google.com>; Steven Wu <stevenwu@apple.com><br>
<b>Subject:</b> Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<div class="MsoNormal" align="center" style="text-align:center"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">
<hr size="2" width="100%" align="center" id="zwchr">
</span></div>
<blockquote style="border:none;border-left:solid #1010FF 1.5pt;padding:0in 0in 0in 4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-family:"Helvetica",sans-serif;color:black">From:
</span></b><span style="font-family:"Helvetica",sans-serif;color:black">"Kevin B via llvm-dev Smith" <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>><br>
<b>To: </b>"James Y Knight" <<a href="mailto:jyknight@google.com">jyknight@google.com</a>>, "Steven Wu" <<a href="mailto:stevenwu@apple.com">stevenwu@apple.com</a>><br>
<b>Cc: </b><a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>, "Clang Dev" <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>><br>
<b>Sent: </b>Saturday, February 6, 2016 4:30:20 PM<br>
<b>Subject: </b>Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">I don't know whether this is an issue in the current implementation, but I wanted to bring up a potential privacy issue.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">In embedding the information, care should be taken to avoid embedding any information that contains personally identifiable information. This can certainly occur</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">if paths need to be embedded, as user names, or other private/confidential information may be present in the naming of directories and paths.</span><span style="color:black"><o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black"><br>
Is this any more of a problem than the information that gets included in the DWARF sections?<br>
<br>
-Hal<o:p></o:p></span></p>
<blockquote style="border:none;border-left:solid #1010FF 1.5pt;padding:0in 0in 0in 4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"> Generally, I suspect</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">that it would be desirable to have an opt-in strategy for designating in the compiler which pieces of information/options need to be saved, and for all options
marked</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">as needed, determine whether there is the possibility/likelihood that they may contain personally identifiable information.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A">Kevin B. Smith</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A"> </span><span style="color:black"><o:p></o:p></span></p>
<div style="border:none;border-left:solid windowtext 1.5pt;padding:0in 0in 0in 4.0pt;border-color:-moz-use-text-color -moz-use-text-color -moz-use-text-color blue">
<div>
<div style="border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in;border-color:-moz-use-text-color -moz-use-text-color">
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black"> llvm-dev [<a href="mailto:llvm-dev-bounces@lists.llvm.org">mailto:llvm-dev-bounces@lists.llvm.org</a>]
<b>On Behalf Of </b>James Y Knight via llvm-dev<br>
<b>Sent:</b> Friday, February 05, 2016 3:13 PM<br>
<b>To:</b> Steven Wu <<a href="mailto:stevenwu@apple.com">stevenwu@apple.com</a>><br>
<b>Cc:</b> LLVM Developers Mailing List <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>>; Clang Dev <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>><br>
<b>Subject:</b> Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files</span><span style="color:black"><o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="color:black">On Fri, Feb 5, 2016 at 6:06 PM, Steven Wu <<a href="mailto:stevenwu@apple.com" target="_blank">stevenwu@apple.com</a>> wrote:<o:p></o:p></span></p>
<blockquote style="border:none;border-left:solid windowtext 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt;border-color:-moz-use-text-color -moz-use-text-color -moz-use-text-color rgb(204, 204, 204)">
<div>
<div>
<div>
<p class="MsoNormal"><span style="color:#222222">I don't think we need any path in the command line section. We only record the command-line options that will affect CodeGen. See my example in one of the preview reply:</span><span style="color:black"><o:p></o:p></span></p>
</div>
</div>
<div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="color:black">$ clang -fembed-bitcode -O0 test.c -c -###<br>
"clang" "-cc1" (...lots of options...) "-o" "test.bc" "-x" "c" "test.c" <--- First stage<br>
"clang" "-cc1" "-triple" "x86_64-apple-macosx10.11.0" "-emit-obj" "-fembed-bitcode" "-O0" "-disable-llvm-optzns" "-o" "test.o" "-x" "ir" "test.bc" <--- Second stage<o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal"><span style="color:black">I can't think of any source path that can affect CodeGen. There should not be any paths other than the bitcode input path and binary output path exists in the second stage and they are excluded from the command
line section as well. -fdebug-prefix-map is consumed by the front-end and prefixed paths are a part of the debug info in the metadata. You don't need to encode -fdebug-prefix-map in the bitcode section to reproduce the object file with the same debug info.
Did that answer your concern?<o:p></o:p></span></p>
</div>
</div>
</blockquote>
</div>
<p class="MsoNormal"><span style="color:black"> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="color:black">Great -- it wasn't clear from the first message if you were just embedding the whole command-line as is. If the plan instead to embed only a few relevant options, I agree there should be no issue as far as paths
go.<o:p></o:p></span></p>
</div>
</div>
</div>
<p class="MsoNormal"><span style="font-family:"Helvetica",sans-serif;color:black"><br>
_______________________________________________<br>
LLVM Developers mailing list<br>
<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black"><br>
<br>
<br>
-- <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">Hal Finkel<br>
Assistant Computational Scientist<br>
Leadership Computing Facility<br>
Argonne National Laboratory<o:p></o:p></span></p>
</div>
</div>
</div>
</div>
</body>
</html>