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diff --git a/docs/Packaging.rst b/docs/Packaging.rst new file mode 100644 index 0000000..6e74158 --- /dev/null +++ b/docs/Packaging.rst @@ -0,0 +1,75 @@ +.. _packaging: + +======================== +Advice on Packaging LLVM +======================== + +.. contents:: + :local: + +Overview +======== + +LLVM sets certain default configure options to make sure our developers don't +break things for constrained platforms. These settings are not optimal for most +desktop systems, and we hope that packagers (e.g., Redhat, Debian, MacPorts, +etc.) will tweak them. This document lists settings we suggest you tweak. + +LLVM's API changes with each release, so users are likely to want, for example, +both LLVM-2.6 and LLVM-2.7 installed at the same time to support apps developed +against each. + +Compile Flags +============= + +LLVM runs much more quickly when it's optimized and assertions are removed. +However, such a build is currently incompatible with users who build without +defining ``NDEBUG``, and the lack of assertions makes it hard to debug problems +in user code. We recommend allowing users to install both optimized and debug +versions of LLVM in parallel. The following configure flags are relevant: + +``--disable-assertions`` + Builds LLVM with ``NDEBUG`` defined. Changes the LLVM ABI. Also available + by setting ``DISABLE_ASSERTIONS=0|1`` in ``make``'s environment. This + defaults to enabled regardless of the optimization setting, but it slows + things down. + +``--enable-debug-symbols`` + Builds LLVM with ``-g``. Also available by setting ``DEBUG_SYMBOLS=0|1`` in + ``make``'s environment. This defaults to disabled when optimizing, so you + should turn it back on to let users debug their programs. + +``--enable-optimized`` + (For svn checkouts) Builds LLVM with ``-O2`` and, by default, turns off + debug symbols. Also available by setting ``ENABLE_OPTIMIZED=0|1`` in + ``make``'s environment. This defaults to enabled when not in a + checkout. + +C++ Features +============ + +RTTI + LLVM disables RTTI by default. Add ``REQUIRES_RTTI=1`` to your environment + while running ``make`` to re-enable it. This will allow users to build with + RTTI enabled and still inherit from LLVM classes. + +Shared Library +============== + +Configure with ``--enable-shared`` to build +``libLLVM-<major>.<minor>.(so|dylib)`` and link the tools against it. This +saves lots of binary size at the cost of some startup time. + +Dependencies +============ + +``--enable-libffi`` + Depend on `libffi <http://sources.redhat.com/libffi/>`_ to allow the LLVM + interpreter to call external functions. + +``--with-oprofile`` + + Depend on `libopagent + <http://oprofile.sourceforge.net/doc/devel/index.html>`_ (>=version 0.9.4) + to let the LLVM JIT tell oprofile about function addresses and line + numbers. |