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On 8/19/11 4:36 PM, Jinwook Shin (HOTWING) wrote:
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<p class="MsoNormal"><span style="font-size: 11.5pt; color:
rgb(85, 85, 85);">Thanks John. Your approach worked fine for
my small toy program. Now, I would like to run my module
pass on a huge project (still a single executable)
consisting of a few thousand bit code files scattered in
many different directories. And some of them are static
libraries. Do you still think it's a good idea to manually
gather and link them with llvm-ld? I've seen other module
pass implementations where they directly patch a specific
version of LLVM or clang, instead of running a shared object
implementation with opt. Which would be the ideal approach
to analyze a program with a module pass? Thanks.</span></p>
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<br>
The question is whether your pass requires having the whole program
to work (or to be effective) or whether it can be done on each
compilation unit separately.<br>
<br>
If you can do it on separate compilation units, integrate it into
Clang. We did this for some of the SAFECode passes in mainline
SAFECode; you can use it as an example.<br>
<br>
If your pass must do whole program analysis (or simply works better
if it does), then you want to add your pass to libLTO and enable the
use of link-time optimization using the -emit-llvm option on the
llmv-gcc/clang command line.<br>
<br>
Note that all libLTO passes are enabled when compiling using
link-time optimization. If you replace libLTO on your system, your
pass is going to be run for every program compiled using link-time
optimization (unless you can make your pass conditional on some
optimization level like -O4 or -O5 that gets communicated from the
compiler front-end to the linker to the plugin). If you're doing
instrumentation, you might want to do what we did in SAFECode:
perform instrumentation in the front-end and then use whole-program
analysis to change/optimize the instrumentation in libLTO. That
way, our libLTO transforms can always be turned on; for
uninstrumented code, they become a no-op.<br>
<br>
-- John T.<br>
<br>
<br>
<blockquote cite="mid:CA5C4EAA.11DFC%25jinshin@microsoft.com"
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<p class="MsoNormal"><b><span style="color:black">From: </span></b><span
style="color:black">John Criswell <<a
moz-do-not-send="true"
href="mailto:criswell@illinois.edu">criswell@illinois.edu</a>><br>
<b>Organization: </b>University of Illinois<br>
<b>Date: </b>Tue, 12 Jul 2011 16:19:06 -0500<br>
<b>To: </b>Jinwook Shin <<a moz-do-not-send="true"
href="mailto:Jinwook.Shin@microsoft.com">Jinwook.Shin@microsoft.com</a>><br>
<b>Cc: </b>"<a moz-do-not-send="true"
href="mailto:llvmdev@cs.uiuc.edu">llvmdev@cs.uiuc.edu</a>"
<<a moz-do-not-send="true"
href="mailto:llvmdev@cs.uiuc.edu">llvmdev@cs.uiuc.edu</a>><br>
<b>Subject: </b>Re: [LLVMdev] running a module pass via
opt on multiple bitcode files<o:p></o:p></span></p>
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<p class="MsoNormal"><span
style="font-size:11.5pt;color:#555555">On 7/12/11 4:11
PM, Jinwook Shin (HOTWING) wrote:
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#404040">Hi,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040">I'm trying
to implement a module pass as a share object to process
an entire program as a unit. The target program is built
from multiple object files, hence multiple bitcode
files. However, it seems that opt does not take the
whole program, but just one bitcode file, "test.bc" in
the example run shown below.
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040">$ opt -load
mypass.dylib -mymodulepass < test.bc > /dev/null</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040">How do I
run my module pass in a library on a whole program?
</span><o:p></o:p></p>
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style="font-size:11.5pt;color:#555555"><br>
Link the bitcode files together into a single bitcode
file with llvm-ld. You can then run the single bitcode
file through opt.<br>
<br>
-- John T.<br>
<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040">Thanks.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#404040"> </span><o:p></o:p></p>
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<br>
<br>
<o:p></o:p></span></p>
<pre><span style="color:#555555">_______________________________________________<o:p></o:p></span></pre>
<pre><span style="color:#555555">LLVM Developers mailing list<o:p></o:p></span></pre>
<pre><span style="color:#555555"><a moz-do-not-send="true" href="mailto:LLVMdev@cs.uiuc.edu">LLVMdev@cs.uiuc.edu</a> <a moz-do-not-send="true" href="http://llvm.cs.uiuc.edu">http://llvm.cs.uiuc.edu</a><a moz-do-not-send="true" href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</a><o:p></o:p></span></pre>
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