LEG Example Backend

This is a simple example LLVM backend for an ARM-like architecture: 'LEG'.

Check out the slides from the tutorial given at Euro LLVM Developers' Conference 2014, Edinburgh: http://llvm.org/devmtg/2014-04/PDFs/Talks/Building%20an%20LLVM%20backend.pdf

Look out for us at the USA LLVM Developers' Conference, October 28-29, San Jose: http://llvm.org/devmtg/2014-10/

Fraser Cormack & Pierre-André Saulais, Codeplay Software

Getting Started

The LEG repositories (llvm-leg, clang-leg) both track tip, and aren't tied to any specific revision of LLVM/Clang.

Tried & tested build systems:

• CMake Tried & tested compilers:
• gcc 4.9.1
• clang 3.5

Building with in-tree clang (optional)

cd llvm-leg
git clone [email protected]:codeplaysoftware/clang-leg.git tools/clang

Building with make

cd llvm-leg
mkdir build && cd build
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE:STRING=DEBUG(/RELEASE) -DLLVM_TARGETS_TO_BUILD:STRING=LEG(,X86,...) ../
make -j9

Building with ninja

cd llvm-leg
mkdir build && cd build
cmake -G "Ninja" -DCMAKE_BUILD_TYPE:STRING=DEBUG(/RELEASE) -DLLVM_TARGETS_TO_BUILD:STRING=LEG(,X86,...) ../
ninja

Compiling some code

cd llvm-leg

### Compile IR -> Assembly ###
./build/bin/llc -march leg -o ex1.s docs/Codeplay/examples/ex1.ll
cat ex1.s

### Compile IR -> ELF Object File ###
./build/bin/llc -march leg -filetype=obj -o ex1.o docs/Codeplay/examples/ex1.ll
xxd ex1.o

### Compile Source -> Assembly with in-tree clang (via clang-leg) ###
./build/bin/clang -cc1 -triple leg-unknown-unknown -S -o ex1.s docs/Codeplay/example/ex1.c
cat ex1.s

### Compile Source -> Assembly with in-tree clang (via clang-leg) ###
./build/bin/clang -cc1 -triple leg-unknown-unknown -o ex1.o docs/Codeplay/example/ex1.c
xxd ex1.0

Low Level Virtual Machine (LLVM)

This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments.

LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.

Please see the documentation provided in docs/ for further assistance with LLVM, and in particular docs/GettingStarted.rst for getting started with LLVM and docs/README.txt for an overview of LLVM's documentation setup.

If you are writing a package for LLVM, see docs/Packaging.rst for our suggestions.