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<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Hello Eli,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Oh, I did not see this
patch as was very busy with my patch and did not follow the mailing. I
apologize. Now I will study it.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>> </span></font><font
size=2 color="#1f497d" face=Calibri><span lang=EN-US style='font-size:11.0pt;
font-family:Calibri;color:#1F497D'>How does your patch relate to this work? It
may be a good idea to discuss all the requirements and possible solutions and
come up with a design that suits everyone. Otherwise it’s hard to review
and reason about several large & conflicting patches to the same area of
code.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>I can offer a few
thoughts for discussion about the design:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>The code should be
emitted by sectors, rather than by functions.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>If we allocate space for
each function separately, there is no guarantee that their position relative to
each other will be the same as it was in the object file. However, if two
functions are in one sector and one calls the other, then this call will at
once direct brunch in the code without any relocation. And if these two
functions will be emitted separately, probably a runtime error will occurred.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>RuntimeDyLdImpl<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Simplistically,
RuntimeDyLd doing the following:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>1. Load an object file:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>1.1. Parse an object
file, finds the functions, data, relocations, etc.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>1.2. Emit functions and
data.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>1.3. Parse relocations,
associate it with the emitted data.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>2. Resolve relocations
after loading all the object files.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>If we will parsing the
object file with the ObjectFile class then the object file formats different
will appear only at stages 1.3 and 2.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>In this case, it makes
sense to most of the work doing in RuntimeDyLdImpl, and only stages 1.3 and 2
doing in RuntimeDyLdMachO and RuntimeDyLdELF.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>ARM<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Some branch instructions
have a limited range. For address outside this range are used special instructions.
Accordingly, we need add a stub function with these instructions when we see
short range branch relocation, because we can not be sure this brunch is out of
range or not.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Perhaps another
architectures need stub-functions also, so it is desirable to make this
mechanism more general.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Regress tests.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>The RuntimeDyLd has only
x86 and ARM relocation resolvers now (in ToT ARM ELF not yet supported, but in
any case, I'll add support for ARM ELF). So it make sense to use an separate
folder for MCJIT ExecutionEngine tests and add to dg.exp a special filter.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Danil<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Bendersky, Eli
[mailto:eli.bendersky@intel.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, February 08, 2012
10:00 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Danil Malyshev;
llvm-commits@cs.uiuc.edu<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: RuntimeDyLd new
features</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>Hi Danil,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>We’re
currently working on getting MCJIT running on ELF
(http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-January/046671.html), and a
couple of patches were already committed. There’s another patch,
currently pending a review (<a
href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120130/135997.html">http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120130/135997.html</a>)
with further changes that make MCJIT on ELF (Linux) pass 100% of ExecutionEngine
tests (all the same tests JIT passes), as well as supporting MCJIT debugging
with GDB.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>How does your patch
relate to this work? It may be a good idea to discuss all the requirements and
possible solutions and come up with a design that suits everyone. Otherwise
it’s hard to review and reason about several large & conflicting
patches to the same area of code.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>Eli<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
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