1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 2 "http://www.w3.org/TR/html4/strict.dtd"> 3<html> 4<head> 5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 6 <title>Advice on Packaging LLVM</title> 7 <link rel="stylesheet" href="llvm.css" type="text/css"> 8</head> 9<body> 10 11<h1>Advice on Packaging LLVM</h1> 12<ol> 13 <li><a href="#overview">Overview</a></li> 14 <li><a href="#compilation">Compile Flags</a></li> 15 <li><a href="#cxx-features">C++ Features</a></li> 16 <li><a href="#shared-library">Shared Library</a></li> 17 <li><a href="#deps">Dependencies</a></li> 18</ol> 19 20<!--=========================================================================--> 21<h2><a name="overview">Overview</a></h2> 22<!--=========================================================================--> 23<div> 24 25<p>LLVM sets certain default configure options to make sure our developers don't 26break things for constrained platforms. These settings are not optimal for most 27desktop systems, and we hope that packagers (e.g., Redhat, Debian, MacPorts, 28etc.) will tweak them. This document lists settings we suggest you tweak. 29</p> 30 31<p>LLVM's API changes with each release, so users are likely to want, for 32example, both LLVM-2.6 and LLVM-2.7 installed at the same time to support apps 33developed against each. 34</p> 35</div> 36 37<!--=========================================================================--> 38<h2><a name="compilation">Compile Flags</a></h2> 39<!--=========================================================================--> 40<div> 41 42<p>LLVM runs much more quickly when it's optimized and assertions are removed. 43However, such a build is currently incompatible with users who build without 44defining NDEBUG, and the lack of assertions makes it hard to debug problems in 45user code. We recommend allowing users to install both optimized and debug 46versions of LLVM in parallel. The following configure flags are relevant: 47</p> 48 49<dl> 50 <dt><tt>--disable-assertions</tt></dt><dd>Builds LLVM with <tt>NDEBUG</tt> 51 defined. Changes the LLVM ABI. Also available by setting 52 <tt>DISABLE_ASSERTIONS=0|1</tt> in <tt>make</tt>'s environment. This defaults 53 to enabled regardless of the optimization setting, but it slows things 54 down.</dd> 55 56 <dt><tt>--enable-debug-symbols</tt></dt><dd>Builds LLVM with <tt>-g</tt>. 57 Also available by setting <tt>DEBUG_SYMBOLS=0|1</tt> in <tt>make</tt>'s 58 environment. This defaults to disabled when optimizing, so you should turn it 59 back on to let users debug their programs.</dd> 60 61 <dt><tt>--enable-optimized</tt></dt><dd>(For svn checkouts) Builds LLVM with 62 <tt>-O2</tt> and, by default, turns off debug symbols. Also available by 63 setting <tt>ENABLE_OPTIMIZED=0|1</tt> in <tt>make</tt>'s environment. This 64 defaults to enabled when not in a checkout.</dd> 65</dl> 66</div> 67 68<!--=========================================================================--> 69<h2><a name="cxx-features">C++ Features</a></h2> 70<!--=========================================================================--> 71<div> 72 73<dl> 74 <dt>RTTI</dt><dd>LLVM disables RTTI by default. Add <tt>REQUIRES_RTTI=1</tt> 75 to your environment while running <tt>make</tt> to re-enable it. This will 76 allow users to build with RTTI enabled and still inherit from LLVM 77 classes.</dd> 78</dl> 79</div> 80 81<!--=========================================================================--> 82<h2><a name="shared-library">Shared Library</a></h2> 83<!--=========================================================================--> 84<div> 85 86<p>Configure with <tt>--enable-shared</tt> to build 87<tt>libLLVM-<var>major</var>.<var>minor</var>.(so|dylib)</tt> and link the tools 88against it. This saves lots of binary size at the cost of some startup time. 89</p> 90</div> 91 92<!--=========================================================================--> 93<h2><a name="deps">Dependencies</a></h2> 94<!--=========================================================================--> 95<div> 96 97<dl> 98<dt><tt>--enable-libffi</tt></dt><dd>Depend on <a 99href="http://sources.redhat.com/libffi/">libffi</a> to allow the LLVM 100interpreter to call external functions.</dd> 101<dt><tt>--with-oprofile</tt></dt><dd>Depend on <a 102href="http://oprofile.sourceforge.net/doc/devel/index.html">libopagent</a> 103(>=version 0.9.4) to let the LLVM JIT tell oprofile about function addresses and 104line numbers.</dd> 105</dl> 106</div> 107 108<!-- *********************************************************************** --> 109<hr> 110<address> 111 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img 112 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> 113 <a href="http://validator.w3.org/check/referer"><img 114 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> 115 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br> 116 Last modified: $Date$ 117</address> 118</body> 119</html> 120