Patch for HowToBuildOnARM documentation from Wei-Ren Chen.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164776 91177308-0d34-0410-b5e6-96231b3b80d8

docs/HowToBuildOnARM.rst

@@ -0,0 +1,34 @@
+.. _how_to_build_on_arm:
+
+===================================================================
+How To Build On ARM
+===================================================================
+
+.. sectionauthor:: 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.
+
+#. 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.
+
+#. If you want to run ``make
+   check-all`` after building LLVM/Clang, to avoid false alarms (eg, ARCMT
+   failure) please use the following configuration:
+
+   .. code-block:: bash
+
+     $ ../$LLVM_SRC_DIR/configure --with-abi=aapcs

docs/userguides.rst

@@ -7,6 +7,7 @@ User Guides
    :hidden:
 
    CMake
+   HowToBuildOnARM
    CommandGuide/index
    DeveloperPolicy
    GettingStartedVS
@@ -28,6 +29,10 @@ User Guides
    An addendum to the main Getting Started guide for those using the `CMake
    build system <http://www.cmake.org>`_.
 
+* :ref:`how_to_build_on_arm`
+
+   Notes on building and testing LLVM/Clang on ARM.
+
 * `Getting Started with the LLVM System using Microsoft Visual Studio
   <GettingStartedVS.html>`_