introduction

I wrote the rterra package that allows the R programmer to write very fast extensions in Lua/Terra language. The Lua bit is executed by LuaJIT, a very very fast Lua just in time compiler. What makes this package powerful is the that the user can write programs in Terra, a statically typed extension to the Lua language. Functions and code written in Terra get compiled to machine code (on the fly) by LLVM.

The user of the rterra package need not have LLVM/Clang present on their systems. The package comes with a self contained library (a hefty 100MB) that contains the necessary bits.

I lost interest in its development primarily because LuaJIT based dynamic libraries would not load in OSX applications compiled without certain flags. In the 2.1.0-beta3, this has now been fixed (a flag LUAJIT_ENABLE_GC64 needs to be set) and now the rterra package can be loaded for OS X and Linux. A windows build is indeed possible, but I dont have the time for that.

This page exists to remind me how to download Clang/LLVM, patch the Terra makefiles and build rterra packages.

The Steps

R Version

I tested with R version 3.3.1 on Centos7 and R version 3.4.0 on macOS Sierra. Be sure to install XCode command line tools on macOS.

Getting LLVM/Clang

We will focus on the LLVM 3.9.1 version. For Centos 7, we will need to download the source and compile both LLVM and Clang. For OSX and Ubuntu we can download binaries.

For checking source out and compiling, i referred to these instructions. We’ll need the latest version of cmake for example Centos7 had an old version of cmake(CMake 3.4.3 or higher is required).

Run

svn ls http://llvm.org/svn/llvm-project/llvm/tags | grep RELEASE

RELEASE_1/
RELEASE_11/
RELEASE_12/
RELEASE_13/
RELEASE_14/
RELEASE_15/
...
...
RELEASE_390/
RELEASE_391/
RELEASE_400/
RELEASE_401/

we will focus on RELEASE_391

mkdir  rterrainstall
mkdir rterrainstall/llvmclang
cd rterrainstall
svn co http://llvm.org/svn/llvm-project/llvm/tags/RELEASE_391/final llvm_RELEASE_391
cd llvm_RELEASE_391/tools
svn co http://llvm.org/svn/llvm-project/cfe/tags/RELEASE_391/final clang
cd ../projects
svn co http://llvm.org/svn/llvm-project/compiler-rt/tags/RELEASE_391/final compiler-rt
svn co http://llvm.org/svn/llvm-project/libcxx/tags/RELEASE_391/final libcxx
svn co http://llvm.org/svn/llvm-project/libcxxabi/tags/RELEASE_391/final libcxxabi
cd ..
svn update

We will then compile it and install it locally inside the build folder.

mkdir ../llvm_RELEASE_391_build
cd ../llvm_RELEASE_391_build
cmake -DCMAKE_BUILD_TYPE=Release ../llvm_RELEASE_391 -DCMAKE_INSTALL_PREFIX=../llvmclang/ && make -j5

and then check versions e.g. clang --version (remember to run it from the install path).

These instructions work(download source and compile) for Centos 7, AWS EMR (c4.2xlarge instances), Ubuntu Precise and macOS Sierra. For macOS and ubuntu, you can also download the binaries without having to compile. But this compilation approach works for all platforms.

Checkout Terra

We will checkout Terra from here and remember to switch the commit hash 67a08ccbddcdec3626ff86c11d6d571bb924522e (on March 15, 2017). This is the commit hash i worked with. These instructions might or might not work with later hashes.

git clone https://github.com/zdevito/terra.git
cd terra
git checkout 67a08ccbddcdec3626ff86c11d6d571bb924522e

We will edit Makefile in the root folder of LuaJIT by modifying the rule to build libluajit to un-comment the LUAJIT_ENABLE_GC64 flag bit (if you copy paste this, change spaces to tabs)

build/lib/libluajit-5.1.a: build/$(LUAJIT_TAR)
        (cd build; tar -xf $(LUAJIT_TAR))
ifeq ($(UNAME), Darwin)
	@echo "On Darwin: Uncommenting LUAJIT_ENABLE_GC64"
        (cd $(LUAJIT_DIR); sed -i -e '/-DLUAJIT_ENABLE_GC64/s/^#//g' src/Makefile)
endif
     	(cd $(LUAJIT_DIR); make install PREFIX=$(realpath build) CC=$(CC) STATIC_CC="$(CC) -fPIC")

Also, for Linux builds and LuaJIT-2.1.0-beta3, the following commands in Makefile

#rule for packaging lua code into a header file
# fix narrowing warnings by using unsigned char
build/%.h:      src/%.lua $(PACKAGE_DEPS)
        $(LUAJIT) -bg $< -t h - | sed "s/char/unsigned char/" > $@

cause unsigned unsigned to be written in some of the generated .h files (e.g. asdl.h). A fix for the version of LuaJIT 2.1.0-beta3 is

build/%.h:      src/%.lua $(PACKAGE_DEPS)
        $(LUAJIT) -bg $< -t h - | sed "s/const char/const unsigned char/" > $@

and we add a Makefile.inc that contains the path to the clang/llvm. This is what it looks like on OSX.

LLVM_CONFIG = /Users/sguha/Downloads/clang+llvm-3.9.0-x86_64-apple-darwin/bin/llvm-config
LUAJIT_VERSION_BASE =2.1
LUAJIT_VERSION_EXTRA =.0-beta3

and what it looks like on Linux

LLVM_CONFIG =/home/sguha/tmp/rterrainstall/llvmclang/bin/llvm-config
LUAJIT_VERSION_BASE =2.1
LUAJIT_VERSION_EXTRA =.0-beta3

Now, compile Terra,

make

Checkout Terrific

Checkout rterra

git clone https://github.com/saptarshiguha/terrific.git
cd terrific/rterra
mkdir copies

Now copy everything from terra’s release folder to copies/ and compile

cp -r  ../../terra/release/* copies/

And now,

R CMD INSTALL .

(or package it as a release)