<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;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 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;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:#1F497D;}
.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:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>My 2c…<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Benefits of the feature clearly outweigh any potential privacy concerns from my point of view… and yes, there are multiple ways to deal with privacy even if it is an issue.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Sergei<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:10.5pt;font-family:Consolas;color:#1F497D'>---<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Calibri",sans-serif;color:#1F497D'>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation</span><span style='font-size:10.5pt;font-family:Consolas;color:#1F497D'><o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><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><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'> llvm-dev [mailto:llvm-dev-bounces@lists.llvm.org] <b>On Behalf Of </b>Steven Wu via llvm-dev<br><b>Sent:</b> Saturday, February 06, 2016 8:04 PM<br><b>To:</b> Smith, Kevin B<br><b>Cc:</b> llvm-dev@lists.llvm.org; Clang Dev<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><p class=MsoNormal>Hi Kevin<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>That is a very good concern and we have ways to address the issue in our bitcode implementation to achieve similar something similar to ‘strip’ (hiding unnecessary symbols and debug info). It wasn’t in the proposal because we would like to get the basics in before diving into something more detailed and controversial. <o:p></o:p></p></div><div><p class=MsoNormal>Here is a short description about how we deal with the issue. Our implementation requires linker support which runs a ‘Linkage-Unit’ pass that consistently rename all the symbols and metadata that are not exported. This has to be done after resolving all the symbols. We would be happy to upstream our implementation if it is beneficial.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Steven<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On Feb 6, 2016, at 2:57 PM, Smith, Kevin B <<a href="mailto:kevin.b.smith@intel.com">kevin.b.smith@intel.com</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'>Hal,</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><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,</span><o:p></o:p></p></div><div><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.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><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</span><o:p></o:p></p></div><div><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.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'>Kevin Smith</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><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'><div><p class=MsoNormal><a name="_____replyseparator"></a><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span class=apple-converted-space><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span></span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Hal Finkel [<a href="mailto:hfinkel@anl.gov">mailto:hfinkel@anl.gov</a>]<span class=apple-converted-space> </span><br><b>Sent:</b><span class=apple-converted-space> </span>Saturday, February 06, 2016 2:37 PM<br><b>To:</b><span class=apple-converted-space> </span>Smith, Kevin B <<a href="mailto:kevin.b.smith@intel.com">kevin.b.smith@intel.com</a>><br><b>Cc:</b><span class=apple-converted-space> </span><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>>; 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>Subject:</b><span class=apple-converted-space> </span>Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files</span><o:p></o:p></p></div></div></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'> </span><o:p></o:p></p></div><div class=MsoNormal align=center style='text-align:center'><span style='font-size:10.0pt;font-family:"Arial",sans-serif'><hr size=2 width="100%" align=center></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'>From:<span class=apple-converted-space> </span></span></b><span style='font-family:"Helvetica",sans-serif'>"Kevin B via llvm-dev Smith" <<a href="mailto:llvm-dev@lists.llvm.org"><span style='color:purple'>llvm-dev@lists.llvm.org</span></a>><br><b>To:<span class=apple-converted-space> </span></b>"James Y Knight" <<a href="mailto:jyknight@google.com"><span style='color:purple'>jyknight@google.com</span></a>>, "Steven Wu" <<a href="mailto:stevenwu@apple.com"><span style='color:purple'>stevenwu@apple.com</span></a>><br><b>Cc:<span class=apple-converted-space> </span></b><a href="mailto:llvm-dev@lists.llvm.org"><span style='color:purple'>llvm-dev@lists.llvm.org</span></a>, "Clang Dev" <<a href="mailto:cfe-dev@lists.llvm.org"><span style='color:purple'>cfe-dev@lists.llvm.org</span></a>><br><b>Sent:<span class=apple-converted-space> </span></b>Saturday, February 6, 2016 4:30:20 PM<br><b>Subject:<span class=apple-converted-space> </span></b>Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files</span><o:p></o:p></p><div><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><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><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><o:p></o:p></p></div><div><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><o:p></o:p></p></div></blockquote><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;font-family:"Arial",sans-serif'><br>Is this any more of a problem than the information that gets included in the DWARF sections?<br><br> -Hal</span><o:p></o:p></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'><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> Generally, I suspect</span><o:p></o:p></p></div><div><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><o:p></o:p></p></div><div><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><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'>Kevin B. Smith</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#44546A'> </span><o:p></o:p></p></div><div style='border:none;border-left:solid windowtext 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid windowtext 1.0pt;padding:3.0pt 0in 0in 0in'><div><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span class=apple-converted-space><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> </span></span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>llvm-dev [<a href="mailto:llvm-dev-bounces@lists.llvm.org"><span style='color:purple'>mailto:llvm-dev-bounces@lists.llvm.org</span></a>]<span class=apple-converted-space> </span><b>On Behalf Of<span class=apple-converted-space> </span></b>James Y Knight via llvm-dev<br><b>Sent:</b><span class=apple-converted-space> </span>Friday, February 05, 2016 3:13 PM<br><b>To:</b><span class=apple-converted-space> </span>Steven Wu <<a href="mailto:stevenwu@apple.com"><span style='color:purple'>stevenwu@apple.com</span></a>><br><b>Cc:</b><span class=apple-converted-space> </span>LLVM Developers Mailing List <<a href="mailto:llvm-dev@lists.llvm.org"><span style='color:purple'>llvm-dev@lists.llvm.org</span></a>>; Clang Dev <<a href="mailto:cfe-dev@lists.llvm.org"><span style='color:purple'>cfe-dev@lists.llvm.org</span></a>><br><b>Subject:</b><span class=apple-converted-space> </span>Re: [llvm-dev] [RFC] Embedding Bitcode in Object Files</span><o:p></o:p></p></div></div></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal>On Fri, Feb 5, 2016 at 6:06 PM, Steven Wu <<a href="mailto:stevenwu@apple.com" target="_blank"><span style='color:purple'>stevenwu@apple.com</span></a>> wrote:<o:p></o:p></p></div><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'><div><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><o:p></o:p></p></div></div></div><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>$ 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></p></div></blockquote><div><p class=MsoNormal>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></p></div></div></div></blockquote></div><div><p class=MsoNormal> <o:p></o:p></p></div></div><div><div><p class=MsoNormal>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></p></div></div></div></div><div><p class=MsoNormal><span style='font-family:"Helvetica",sans-serif'><br>_______________________________________________<br>LLVM Developers mailing list<br><a href="mailto:llvm-dev@lists.llvm.org"><span style='color:purple'>llvm-dev@lists.llvm.org</span></a><br><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev"><span style='color:purple'>http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</span></a></span><o:p></o:p></p></div></blockquote><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'><br><br><br>--<span class=apple-converted-space> </span></span><o:p></o:p></p></div><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Hal Finkel<br>Assistant Computational Scientist<br>Leadership Computing Facility<br>Argonne National Laboratory</span><o:p></o:p></p></div></div></div></div></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></div></body></html>