[llvm-dev] How do I generate a combined .ll file from makefile or configure file?

[Shen Liu via llvm-dev]

Hi Ketan,

Using LLVM gold plugin is a fast way to generate a whole-program.bc after
make.

Here is a great article guiding you how to do this:

(Compiling autotooled projects to LLVM bitcode )
http://gbalats.github.io/2015/12/10/compiling-autotooled-projects-to-LLVM-bitcode.html

The git repo for binutils doesn't work, but you can grab a version here:
http://ftp.gnu.org/gnu/binutils/ I believe I used 2.26, but latest 2.27
should also work.
When building binutils make sure to follow http://llvm.org/docs/
GoldPlugin.html for configuring and building. Once this is complete you
will have the binutils gold linker installed.

Some key operations are as follows:

$ export CC=clang$ export CXX=clang++$ export RANLIB=llvm-ranlib$
export CFLAGS=" -flto -std=gnu99 "$ export LDFLAGS=" -flto
-fuse-ld=gold "$ ./configure

LDFLAGS =  -flto -fuse-ld=gold -Wl,-plugin-opt=emit-llvm

Usually I don't change .configure too much, instead, I will change these
options in Makefile because I clearly know what I am doing.

You can also change clang source code to enable "also-emit-llvm", which can
generate .bc together with the executable.

LDFLAGS = -flto -fuse-ld=gold -Wl,-plugin-opt=also-emit-llvm

Good Luck!

On Sun, Aug 13, 2017 at 6:57 AM, Ketan Patil via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I wrote a module pass to generate a call graph. I want to generate call
> graph which would consist of all the functions like the functions in the
> user code as well as the functions in the libraries.
>
> To be more specific, I am working with binutils 2.26
> https://ftp.gnu.org/gnu/binutils/binutils-2.26.tar.gz
>
> I want to generate the call graph for 'objdump'. The code of the objdump
> would call some functions in the library 'libiberty' these called functions
> in the library can call more internal functions inside the library.
>
> I want a call graph which will include all such functions.
>
> One way to do is that I can emit llvm code for all the files in the
> library as well as the user code in separate .ll files. And then finally
> combine them using llvm-link. But this may fail if there are dependencies
> here and there. So can I do this systematically by making some changes in *configure
> file* or *makefile* without disturbing any dependencies.
>
> Any help is highly appreciated.
> Thanks and regards
> -Ketan Patil
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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