How To Build On ARM

Section author: Wei-Ren Chen (陳韋任) <chenwj@iis.sinica.edu.tw>

Introduction

This document contains information about building/testing LLVM and Clang on ARM.

Notes On Building LLVM/Clang on ARM

Here are some notes on building/testing LLVM/Clang on ARM. Note that ARM encompasses a wide variety of CPUs; this advice is primarily based on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips.

1. If you are building LLVM/Clang on an ARM board with 1G of memory or less, please use gold rather then GNU ld. Building LLVM/Clang with --enable-optimized is prefered since it consumes less memory. Otherwise, the building process will very likely fail due to insufficient memory. In any case it is probably a good idea to set up a swap partition.

2. If you want to run make check-all after building LLVM/Clang, to avoid false alarms (eg, ARCMT failure) please use at least the following configuration:

   $ ../$LLVM_SRC_DIR/configure --with-abi=aapcs-vfp
   

3. The most popular linaro/ubuntu OS’s for ARM boards, eg, the Pandaboard, have become hard-float platforms. The following set of configuration options appears to be a good choice for this platform:

   ./configure --build=armv7l-unknown-linux-gnueabihf
   --host=armv7l-unknown-linux-gnueabihf
   --target=armv7l-unknown-linux-gnueabihf --with-cpu=cortex-a9
   --with-float=hard --with-abi=aapcs-vfp --with-fpu=neon
   --enable-targets=arm --disable-optimized --enable-assertions