1 .. _packaging: 2 3 ======================== 4 Advice on Packaging LLVM 5 ======================== 6 7 .. contents:: 8 :local: 9 10 Overview 11 ======== 12 13 LLVM sets certain default configure options to make sure our developers don't 14 break things for constrained platforms. These settings are not optimal for most 15 desktop systems, and we hope that packagers (e.g., Redhat, Debian, MacPorts, 16 etc.) will tweak them. This document lists settings we suggest you tweak. 17 18 LLVM's API changes with each release, so users are likely to want, for example, 19 both LLVM-2.6 and LLVM-2.7 installed at the same time to support apps developed 20 against each. 21 22 Compile Flags 23 ============= 24 25 LLVM runs much more quickly when it's optimized and assertions are removed. 26 However, such a build is currently incompatible with users who build without 27 defining ``NDEBUG``, and the lack of assertions makes it hard to debug problems 28 in user code. We recommend allowing users to install both optimized and debug 29 versions of LLVM in parallel. The following configure flags are relevant: 30 31 ``--disable-assertions`` 32 Builds LLVM with ``NDEBUG`` defined. Changes the LLVM ABI. Also available 33 by setting ``DISABLE_ASSERTIONS=0|1`` in ``make``'s environment. This 34 defaults to enabled regardless of the optimization setting, but it slows 35 things down. 36 37 ``--enable-debug-symbols`` 38 Builds LLVM with ``-g``. Also available by setting ``DEBUG_SYMBOLS=0|1`` in 39 ``make``'s environment. This defaults to disabled when optimizing, so you 40 should turn it back on to let users debug their programs. 41 42 ``--enable-optimized`` 43 (For svn checkouts) Builds LLVM with ``-O2`` and, by default, turns off 44 debug symbols. Also available by setting ``ENABLE_OPTIMIZED=0|1`` in 45 ``make``'s environment. This defaults to enabled when not in a 46 checkout. 47 48 C++ Features 49 ============ 50 51 RTTI 52 LLVM disables RTTI by default. Add ``REQUIRES_RTTI=1`` to your environment 53 while running ``make`` to re-enable it. This will allow users to build with 54 RTTI enabled and still inherit from LLVM classes. 55 56 Shared Library 57 ============== 58 59 Configure with ``--enable-shared`` to build 60 ``libLLVM-<major>.<minor>.(so|dylib)`` and link the tools against it. This 61 saves lots of binary size at the cost of some startup time. 62 63 Dependencies 64 ============ 65 66 ``--enable-libffi`` 67 Depend on `libffi <http://sources.redhat.com/libffi/>`_ to allow the LLVM 68 interpreter to call external functions. 69 70 ``--with-oprofile`` 71 72 Depend on `libopagent 73 <http://oprofile.sourceforge.net/doc/devel/index.html>`_ (>=version 0.9.4) 74 to let the LLVM JIT tell oprofile about function addresses and line 75 numbers. 76
