The Low Level Virtual Machine (LLVM) is an open source compiler infrastructure that provides modular and reusable compiler and toolchain technologies. LLVM can compile C/C++ code and generate optimized machine code for multiple platforms. It works as an intermediate representation between source code and machine code by first compiling source code to LLVM's own intermediate language, then performing optimizations on that code before generating target machine code.

1. LLVM
2009 1 15 ( )

2. LLVM
Tatsuhiro Ujihisa

3. LLVM
The Low Level Virtual Machine (LLVM) is a compiler
infrastructure, written in C++, which is designed for compile-
time, link-time, run-time, and "idle-time" optimization of
programs written in arbitrary programming languages. LLVM
was originally developed as a research infrastructure at the
University of Illinois at Urbana-Champaign to investigate
dynamic compilation techniques for static and dynamic
programming languages...
http://en.wikipedia.org/wiki/Low_Level_Virtual_Machine

4. In short,
C JVM
gcc
( )
( )

5. C
C→ → →
$ vim a.c
$ gcc a.c -S -o a.s
$ gcc a.s -o a
$ ./a

6. LLVM (1)
C → LLVM → LLVM →
$ vim a.c
$ llvm-gcc a.c -S -o a.ll
$ llvm-as a.ll -o a.bc
$ lli a.bc

7. LLVM (2)
C → LLVM → LLVM → →
$ vim a.c
$ llvm-gcc a.c -S -o a.ll
$ llvm-as a.ll -o a.bc
$ llc a.bc -o a
$ ./a

8. LLVM (3)
LLVM → LLVM →
$ vim a.ll
$ llvm-as a.ll -o a.bc
$ lli a.bc

9. LLVM (4)
LLVM → LLVM → →
$ vim a.ll
$ llvm-as a.ll -o a.bc
$ opt a.bc -o a2.bc
$ lli a2.bc

10. LLVM (5)
LLVM → LLVM → → →
$ vim a.ll
$ llvm-as a.ll -o a.bc
$ opt -O3 a.bc -o a2.bc
$ opt -O3 a2.bc -o a3.bc
$ lli a3.bc

11. LLVM
$ llvm-as a.ll -o a.bc
$ opt -O3 a.bc -o a2.bc
$ opt -O3 a2.bc -o a3.bc
$ llvm-dis a3.bc -o a3.ll
$ vim a3.ll

12. llvm-as: LLVM (.ll)
LLVM (.bc)
lli: LLVM (.bc)
opt: LLVM (.bc) LLVM
(.bc)
llvm-dis: llvm-as
llvm-gcc: C (.c) LLVM
(.ll)

13. LLVM Hello,
world!
Hello, world!
@str = internal constant [14 x i8] c"Hello, world!00"
declare i32 @puts(i8*)
define i32 @main()
{
call i32 @puts( i8* getelementptr ([14 x i8]* @str, i32
ret i32 0
}

14. LLVM
( )
C

15. Vim quickrun LLVM
.ll <Space>r llvm-as lli

16. LLVM
LLVM
OK (C OK)
LLVM Mac, Linux, Windows

17. LLVM ( )
C (llvm-gcc)
Perl
Python (pypy)
Ruby (Rubinius, MacRuby, etc)
Haskell
Brainf**k
... LLVM

18. LLVM
Pure
( )
Haskell
sudo port install pure

19. LLVM
LLVM
LLVM

20. ( )
LLVM
(MacRuby)
( svn up)

21. !
Brainf**k → LLVM
BFC: Brainf**k Compiler
git clone
git://github.com/ujihisa/bfc.git
vim bfc/bfc.rb

22. :+
+:
/* C */
/* char *h */
++*h;
LLVM !→
OK

23. (bfc.rb )
when '+'
a = tc += 1; b = tc += 1; c = tc += 1; d = tc += 1
"%tmp#{a} = load i32* %i, align 4n" <<
"%tmp#{b} = getelementptr [1024 x i8]* %h, i32 0, i32 %
"%tmp#{c} = load i8* %tmp#{b}, align 1n" <<
"%tmp#{d} = add i8 1, %tmp#{c}n" <<
"store i8 %tmp#{d}, i8* %tmp#{b}, align 1n"
1.
2.
3.
4. 1

24. $ cat helloworld.bf
$ cat helloworld.bf | ruby bfc.rb --llvm > helloworld.ll
$ llvm-as helloworld.ll > helloworld.bc
$ opt -O3 helloworld.bc #
$ lli helloworld.bc
Hello, world!
$ ruby bfc.rb --llvm helloworld.bf --run

25. :
BFC: Brainf**k Compilers
http://ujihisa.blogspot.com/2009/12/bfc-
brainfk-compilers.html
LLVM For Starters
http://ujihisa.blogspot.com/2009/12/llvm-
for-starters.html
Let's Try LLVM
http://ujihisa.blogspot.com/2009/12/let-
try-llvm.html

26. nil try-llvm.html