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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi Chris,<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'>Thanks for the info. I’ll probably try disabling the Intel
and AT&T asm printers then, once I have everything else going for my
project. I’ll get back on this topic in due time to see what the other
potential size reducing measures are. I was just hoping maybe there are some
simple options already available, but I don’t mind stepping up and doing
it myself if I can get some guidelines.<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'>Cheers,<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'>Nicolas<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'>P.S: It’s Nicolas, not Nicholas ;-)<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>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu] <b>On Behalf
Of </b>Chris Lattner<br>
<b>Sent:</b> Wednesday, 28 May, 2008 08:02<br>
<b>To:</b> LLVM Developers Mailing List<br>
<b>Subject:</b> Re: [LLVMdev] LLVM project binary size<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>On May 25, 2008, at 11:29 PM, Nicolas Capens wrote:<o:p></o:p></p>
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<p class=MsoNormal><br>
<br>
<o:p></o:p></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>Hi all,<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>I’m a little bit worried about the sheer size of the
resulting binaries of a project using LLVM. The medium large project for which
I’m planning to use it (which currently uses a custom dynamic code
generator), produces a compact 1.6 MB binary. When I compile LLVM’s
simple ‘Fibonacci’ example project the executable is 2.6 MB…<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>I realize LLVM is a complex and feature rich project but could
anyone give me a rough idea of where most of the executable size is coming
from, and maybe give some ideas on how to reduce it if possible?<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'>It’s not like 2.6 MB is huge but it just seems
disproportionate and I’d like to keep my project lightweight (it could be
used for embedded systems one day). Note that I’m basically only using
the IRBuilder, JIT, and a few common optimization passes. Removing the
optimizations doesn’t seem to affect the executable size at all, so
I’m starting to wonder whether there are a lot of other unused features
ending up in the binary (I’m using Visual C++ 2005 by the way, which is
supposed to be quite good at reducing code size). Maybe there is some way to
explicitly disable unused features (not compile them or use stubs)? I’m
also under the impression that LLVM uses a lot of static (pre-generated)
tables, and maybe they could be somewhat smaller when making some extra
assumptions?<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Hi Nicholas,<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>As others have mentioned, the first step is to find out what
is consuming the size. We have done some work to reduce code size, but
there is still a lot that we can do. For example, we know that killing
off the last few uses or RTTI info will shrink generated code size by 5-10% or
so.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>There are other refactorings that can be done to reduce
executable size. Specifically, if you're using a JIT, there is no reason
to link in the code to do .s file printing (and X86 has two versions of this
code). This code is non-trivial and pulls in some big string tables.
Getting this out of the JIT code footprint would require refactoring the
asmprinter stuff so that it isn't accessible via the X86 target's vtable.
This is very doable, but noone has stepped up to do it yet.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>I'm sure that there are a ton of other similar things that
can be done to squeeze it down.<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>-Chris <o:p></o:p></p>
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