[llvm-dev] big module for a project

[Yuxi Chen via llvm-dev]

Hi John,

Really appreciate your detailed information.
The first one works for me.
I will take a look at the third solution.

Thanks again,
Yuxi
________________________________
From: John Criswell [jtcriswel at gmail.com]
Sent: Friday, March 11, 2016 11:26 AM
To: Yuxi Chen; llvm-dev at lists.llvm.org
Cc: llvmdev-bounces at cs.uiuc.edu; llvmdev at cs.uiuc.edu
Subject: Re: [llvm-dev] big module for a project

Dear Yuxi,

There are three general ways to do this (two of which have already been mentioned).

First, you can change the Makefiles to emit bitcode and then use llvm-link to link all the bitcode files together into a big bitcode file.  You can then run the opt program on this large bitcode file.

Second, you can use some third-party tools (for lack of a better term) that will get you a single bitcode file with fewer changes to the Makefiles.  I'm not very familiar with these, but I think others have commented on them.

Third, you can add your analysis pass to the libLTO library and use LLVM's link-time optimization framework to run your analysis.  Documentation libLTO can be found at http://llvm.org/docs/LinkTimeOptimization.html and http://llvm.org/docs/GoldPlugin.html.  LLVM's LTO infrastructure is designed to be transparent (i.e., you shouldn't have to modify Makefiles to use it), though some programs' Makefiles are more...complaint than others.

I've used the libLTO approach for large programs with reasonable success.  However, some of the other third-party approaches have been reported to work well, so you might try looking at those.

Regards,

John Criswell

On 3/10/16 9:54 PM, Yuxi Chen via llvm-dev wrote:
Hi All,

I am using clang to compile Mysql source code. Because I want to do some inter-procedural analysis, hopefully, I want to get a .o(bitcode) file(a module) containing all possible function declarations and definitions. Is it possible to do that ? Or you guys have some suggestions?

To be clear, like Mysql, there is a mysqld routine, which is a major routine. I want to mysqld.o(which is generated by clang) to contain all possible function declarations and definitions. So when I do some analysis, I just need load one module, which is mysqld.o, instead of all .o files.


Best,
Yuxi



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--
John Criswell
Assistant Professor
Department of Computer Science, University of Rochester
http://www.cs.rochester.edu/u/criswell
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