1======================== 2Advice on Packaging LLVM 3======================== 4 5.. contents:: 6 :local: 7 8Overview 9======== 10 11LLVM sets certain default configure options to make sure our developers don't 12break things for constrained platforms. These settings are not optimal for most 13desktop systems, and we hope that packagers (e.g., Redhat, Debian, MacPorts, 14etc.) will tweak them. This document lists settings we suggest you tweak. 15 16LLVM's API changes with each release, so users are likely to want, for example, 17both LLVM-2.6 and LLVM-2.7 installed at the same time to support apps developed 18against each. 19 20Compile Flags 21============= 22 23LLVM runs much more quickly when it's optimized and assertions are removed. 24However, such a build is currently incompatible with users who build without 25defining ``NDEBUG``, and the lack of assertions makes it hard to debug problems 26in user code. We recommend allowing users to install both optimized and debug 27versions of LLVM in parallel. The following configure flags are relevant: 28 29``--disable-assertions`` 30 Builds LLVM with ``NDEBUG`` defined. Changes the LLVM ABI. Also available 31 by setting ``DISABLE_ASSERTIONS=0|1`` in ``make``'s environment. This 32 defaults to enabled regardless of the optimization setting, but it slows 33 things down. 34 35``--enable-debug-symbols`` 36 Builds LLVM with ``-g``. Also available by setting ``DEBUG_SYMBOLS=0|1`` in 37 ``make``'s environment. This defaults to disabled when optimizing, so you 38 should turn it back on to let users debug their programs. 39 40``--enable-optimized`` 41 (For svn checkouts) Builds LLVM with ``-O2`` and, by default, turns off 42 debug symbols. Also available by setting ``ENABLE_OPTIMIZED=0|1`` in 43 ``make``'s environment. This defaults to enabled when not in a 44 checkout. 45 46C++ Features 47============ 48 49RTTI 50 LLVM disables RTTI by default. Add ``REQUIRES_RTTI=1`` to your environment 51 while running ``make`` to re-enable it. This will allow users to build with 52 RTTI enabled and still inherit from LLVM classes. 53 54Shared Library 55============== 56 57Configure with ``--enable-shared`` to build 58``libLLVM-<major>.<minor>.(so|dylib)`` and link the tools against it. This 59saves lots of binary size at the cost of some startup time. 60 61Dependencies 62============ 63 64``--enable-libffi`` 65 Depend on `libffi <http://sources.redhat.com/libffi/>`_ to allow the LLVM 66 interpreter to call external functions. 67 68``--with-oprofile`` 69 70 Depend on `libopagent 71 <http://oprofile.sourceforge.net/doc/devel/index.html>`_ (>=version 0.9.4) 72 to let the LLVM JIT tell oprofile about function addresses and line 73 numbers. 74