Let's Try LLVM

Mac OS X has LLVM compiler, but doesn't have LLVM Assembler. Let's start installing the trunk LLVM on your Mac.

According to http://llvm.org/docs/GettingStarted.html#checkout,

$ cd ~/src
$ svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
$ cd llvm

In the directory there is /docs directory which contains many html files. Check them.

$ ./configure --prefix=/Users/ujihisa/src/llvm/usr
$ gmake -k |& tee gnumake.out

It took long time. After the build process, I found an interesting note.

...
gmake[1]: Leaving directory `/Users/ujihisa/src/llvm/bindings'
llvm[0]: ***** Completed Debug Build
llvm[0]: ***** Note: Debug build can be 10 times slower than an
llvm[0]: ***** optimized build. Use make ENABLE_OPTIMIZED=1 to
llvm[0]: ***** make an optimized build. Alternatively you can
llvm[0]: ***** configure with --enable-optimized.

I should have set --enable-optimized.

Anyway, let the installation finish.

$ gmake install

It also took time.

Don't forget to make path to the ./usr/bin/. There are many llvm-related executable files.

Hello, world!

Let's write hello world on LLVM!

I referred this page. The sample code contains a small mistakes, so I fixed.

Write the following code on a.ll (not a.11):

@str = internal constant [13 x i8] c"hello world\0A\00"

define void @main() nounwind
{
  %temp = call i32 @printf( i8* getelementptr ([13 x i8]* @str, i32 0,i32 0))
  ret void;
}

declare i32 @printf(i8*, ...) nounwind

Assemble it:

$ llvm-as -f a.ll
$ lli a.bc
hello world

Yay!

The generated file a.bc is a binary file.

Vim

Fortunately the svn repository contains a vim script for llvm named llvm.vim. You should install it if you're a vimmer.

(To be continued...)