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gerrit-public.fairphone.software / toolchain / llvm-project / 38d22f69fcd697085a3445ce1b2853b13118e656 / . / llvm / docs / ReleaseNotes.html
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Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
Reid Spencere4190fa2004-11-18 18:38:58 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]6 <link rel="stylesheet" href="llvm.css" type="text/css">
Dan Gohman62af9d22010-05-03 23:51:05 +0000[diff] [blame]7 <title>LLVM 2.8 Release Notes</title>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]10
Dan Gohman62af9d22010-05-03 23:51:05 +0000[diff] [blame]11<div class="doc_title">LLVM 2.8 Release Notes</div>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +0000[diff] [blame]12
Chris Lattnerc871bac2010-03-17 04:02:39 +0000[diff] [blame]13<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greif27b166352010-04-22 10:21:43 +0000[diff] [blame]14 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattnerc871bac2010-03-17 04:02:39 +0000[diff] [blame]15
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]16<ol>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#intro">Introduction</a></li>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]18 <li><a href="#subproj">Sub-project Status Update</a></li>
Dan Gohman62af9d22010-05-03 23:51:05 +0000[diff] [blame]19 <li><a href="#externalproj">External Projects Using LLVM 2.8</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 2.8?</a></li>
Chris Lattner77a51732004-04-30 22:17:12 +0000[diff] [blame]21 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Dan Gohmanad888912008-10-14 16:23:02 +0000[diff] [blame]22 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]23 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]24</ol>
25
Chris Lattner020e1fc2004-05-23 21:07:27 +0000[diff] [blame]26<div class="doc_author">
Dan Gohmanad888912008-10-14 16:23:02 +0000[diff] [blame]27 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]28</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]29
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]30<!--
Chris Lattner656db162010-04-22 05:41:35 +0000[diff] [blame]31<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000[diff] [blame]32release.<br>
33You may prefer the
Dan Gohman62af9d22010-05-03 23:51:05 +0000[diff] [blame]34<a href="http://llvm.org/releases/2.7/docs/ReleaseNotes.html">LLVM 2.7
35Release Notes</a>.</h1>
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]36-->
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000[diff] [blame]37
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]38<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]39<div class="doc_section">
40 <a name="intro">Introduction</a>
41</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]42<!-- *********************************************************************** -->
43
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]44<div class="doc_text">
45
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]46<p>This document contains the release notes for the LLVM Compiler
Dan Gohman3b763f42010-05-03 23:52:21 +0000[diff] [blame]47Infrastructure, release 2.8. Here we describe the status of LLVM, including
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]48major improvements from the previous release and significant known problems.
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000[diff] [blame]49All LLVM releases may be downloaded from the <a
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]50href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]51
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]52<p>For more information about LLVM, including information about the latest
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]53release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]54web site</a>. If you have questions or comments, the <a
Chris Lattner0b1c9a52010-03-17 04:41:49 +0000[diff] [blame]55href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
56Mailing List</a> is a good place to send them.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]57
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +0000[diff] [blame]58<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]59main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif355f81c2008-10-14 11:00:32 +0000[diff] [blame]60current one. To see the release notes for a specific release, please see the
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]61<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]62
63</div>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]64
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]65
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]66<!--
67Almost dead code.
68 include/llvm/Analysis/LiveValues.h => Dan
69 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
70 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner13ee7952010-08-28 04:09:24 +0000[diff] [blame]71 GEPSplitterPass
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]72-->
73
74
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]75<!-- Features that need text if they're finished for 2.9:
Chris Lattnera67df2d2010-04-22 06:28:20 +0000[diff] [blame]76 combiner-aa?
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]77 strong phi elim
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]78 loop dependence analysis
Chris Lattnerbd244042010-08-28 16:33:36 +0000[diff] [blame]79 TBAA
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]80 CorrelatedValuePropagation
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000[diff] [blame]81 -->
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]82
83 <!-- Announcement, lldb, libc++ -->
Chris Lattner16be34d2010-09-29 07:25:03 +0000[diff] [blame]84
85 <!-- to write:
86 MachineCSE tuned and on by default.
87 llvm.dbg.value: variable debug info for optimized code
88 MC Assembler backend is now real, does relaxation and is bitwise identical
89 with darwin assembler in huge majority of all cases.
90 new GHC calling convention
91 New half float intrinsics LangRef.html#int_fp16
92 Rewrote tblgen's type inference for backends to be more consistent and
93 diagnose more target bugs. This also allows limited support for writing
94 patterns for instructions that return multiple results, e.g. a virtual
95 register and a flag result. Stuff that used 'parallel' before should use
96 this.
97 New ARM/Thumb disassembler support in MC.
98 New SSEDomainFix pass:
99 On Nehalem and newer CPUs there is a 2 cycle latency penalty on using a
100 register in a different domain than where it was defined. Some instructions
101 have equvivalents for different domains, like por/orps/orpd. The
102 SSEDomainFix pass tries to minimize the number of domain crossings by
103 changing between equvivalent opcodes where possible.
104 Support for the Intel AES instructions in the assembler.
105 memcpy, memmove, and memset now take address space qualified pointers + volatile.
106
107 -->
108
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000[diff] [blame]109
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]110<!-- *********************************************************************** -->
111<div class="doc_section">
112 <a name="subproj">Sub-project Status Update</a>
Chris Lattner625a3d82008-06-08 21:34:41 +0000[diff] [blame]113</div>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]114<!-- *********************************************************************** -->
Chris Lattner625a3d82008-06-08 21:34:41 +0000[diff] [blame]115
116<div class="doc_text">
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]117<p>
Dan Gohman62af9d22010-05-03 23:51:05 +0000[diff] [blame]118The LLVM 2.8 distribution currently consists of code from the core LLVM
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]119repository (which roughly includes the LLVM optimizers, code generators
120and supporting tools), the Clang repository and the llvm-gcc repository. In
121addition to this code, the LLVM Project includes other sub-projects that are in
122development. Here we include updates on these subprojects.
Bill Wendlingf170d2e2009-03-02 04:28:57 +0000[diff] [blame]123</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]124
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]125</div>
126
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]127
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]128<!--=========================================================================-->
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]129<div class="doc_subsection">
Chris Lattner44c09cd2008-10-13 18:11:54 +0000[diff] [blame]130<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]131</div>
132
133<div class="doc_text">
134
Chris Lattner5de7f6e2010-04-26 17:42:18 +0000[diff] [blame]135<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
136C++, and Objective-C languages. Clang aims to provide a better user experience
137through expressive diagnostics, a high level of conformance to language
138standards, fast compilation, and low memory use. Like LLVM, Clang provides a
139modular, library-based architecture that makes it suitable for creating or
140integrating with other development tools. Clang is considered a
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]141production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
142(32- and 64-bit), and for darwin-arm targets.</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]143
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]144<p>In the LLVM 2.8 time-frame, the Clang team has made many improvements:</p>
Bill Wendlingef362462008-10-27 09:27:33 +0000[diff] [blame]145
Daniel Dunbarc11b40f2008-10-14 23:25:09 +0000[diff] [blame]146<ul>
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]147<li>Surely these guys have done something</li>
Bill Wendling87adbe42009-03-02 04:28:18 +0000[diff] [blame]148</ul>
Chris Lattner44c09cd2008-10-13 18:11:54 +0000[diff] [blame]149</div>
150
151<!--=========================================================================-->
152<div class="doc_subsection">
153<a name="clangsa">Clang Static Analyzer</a>
154</div>
155
156<div class="doc_text">
157
Chris Lattner2284b6a2010-04-22 06:38:11 +0000[diff] [blame]158<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
159 project is an effort to use static source code analysis techniques to
160 automatically find bugs in C and Objective-C programs (and hopefully <a
161 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
162 future</a>!). The tool is very good at finding bugs that occur on specific
163 paths through code, such as on error conditions.</p>
Chris Lattnerbcffa5a2008-10-14 00:52:49 +0000[diff] [blame]164
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]165<p>In the LLVM 2.8 time-frame,
Chris Lattner2284b6a2010-04-22 06:38:11 +0000[diff] [blame]166</p>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]167
168</div>
169
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]170<!--=========================================================================-->
171<div class="doc_subsection">
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000[diff] [blame]172<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]173</div>
174
175<div class="doc_text">
176<p>
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000[diff] [blame]177The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]178a JVM and a CLI Virtual Machine (Microsoft .NET is an
179implementation of the CLI) using LLVM for static and just-in-time
180compilation.</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]181
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]182<p>With the release of LLVM 2.8, ...</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000[diff] [blame]183
184</div>
185
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]186
187<!--=========================================================================-->
188<div class="doc_subsection">
189<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
190</div>
191
192<div class="doc_text">
193<p>
194The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
195is a simple library that provides an implementation of the low-level
196target-specific hooks required by code generation and other runtime components.
197For example, when compiling for a 32-bit target, converting a double to a 64-bit
198unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
199function. The compiler-rt library provides highly optimized implementations of
200this and other low-level routines (some are 3x faster than the equivalent
201libgcc routines).</p>
202
203<p>
204All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]205License, a "BSD-style" license. New in LLVM 2.8:
206
207Soft float support
208</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]209
210</div>
211
212<!--=========================================================================-->
213<div class="doc_subsection">
Duncan Sands92452b92010-04-02 09:23:15 +0000[diff] [blame]214<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]215</div>
216
217<div class="doc_text">
218<p>
Duncan Sands92452b92010-04-02 09:23:15 +0000[diff] [blame]219<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
220gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
221gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
222whatsoever (currently one small patch is needed). This is thanks to the new
223<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
224makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
225which is nothing more than a dynamic library which conforms to the gcc plugin
226interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
227instead of the gcc optimizers, and the LLVM code generators instead of the gcc
228code generators, just like llvm-gcc. To use it, you add
229"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
230becomes llvm-gcc-4.5!
231</p>
232
233<p>
234DragonEgg is still a work in progress. Currently C works very well, while C++,
235Ada and Fortran work fairly well. All other languages either don't work at all,
236or only work poorly. For the moment only the x86-32 and x86-64 targets are
Duncan Sands4dd125e2010-04-20 19:40:58 +0000[diff] [blame]237supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands92452b92010-04-02 09:23:15 +0000[diff] [blame]238</p>
239
240<p>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]2412.8 status here.
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]242</p>
243
244</div>
245
246
247<!--=========================================================================-->
248<div class="doc_subsection">
249<a name="mc">llvm-mc: Machine Code Toolkit</a>
250</div>
251
252<div class="doc_text">
253<p>
Chris Lattner2284b6a2010-04-22 06:38:11 +0000[diff] [blame]254The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
255of problems in the realm of assembly, disassembly, object file format handling,
256and a number of other related areas that CPU instruction-set level tools work
257in. It is a sub-project of LLVM which provides it with a number of advantages
258over other compilers that do not have tightly integrated assembly-level tools.
259For a gentle introduction, please see the <a
260href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
261LLVM MC Project Blog Post</a>.
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]262</p>
263
Chris Lattner16be34d2010-09-29 07:25:03 +0000[diff] [blame]264<p>2.8 status here. Basic correctness, some obscure missing instructions on
265 mainline, on by default in clang.
266 Entire compiler backend converted to use mcstreamer.
267 </p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]268</div>
269
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]270<!--=========================================================================-->
271<div class="doc_subsection">
272<a name="lldb">LLDB: Low Level Debugger</a>
273</div>
274
275<div class="doc_text">
276<p>
277<a href="http://lldb.llvm.org/">LLDB</a> is</p>
278
279<p>
280</p>
281
282<p>
2832.8 status here.
284</p>
285
286</div>
287
288<!--=========================================================================-->
289<div class="doc_subsection">
290<a name="libc++">libc++: C++ Standard Library</a>
291</div>
292
293<div class="doc_text">
294<p>
295<a href="http://libc++.llvm.org/">libc++</a> is</p>
296
297<p>
298</p>
299
300<p>
3012.8 status here.
302</p>
303
304</div>
305
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]306
Chris Lattner53e06f92009-02-26 22:33:38 +0000[diff] [blame]307<!-- *********************************************************************** -->
308<div class="doc_section">
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]309 <a name="externalproj">External Open Source Projects Using LLVM 2.8</a>
Chris Lattner53e06f92009-02-26 22:33:38 +0000[diff] [blame]310</div>
311<!-- *********************************************************************** -->
312
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]313<div class="doc_text">
314
315<p>An exciting aspect of LLVM is that it is used as an enabling technology for
316 a lot of other language and tools projects. This section lists some of the
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]317 projects that have already been updated to work with LLVM 2.8.</p>
Chris Lattnerdf85c892010-04-26 17:38:10 +0000[diff] [blame]318</div>
319
Chris Lattner64694df2010-04-22 21:34:16 +0000[diff] [blame]320
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]321<!-- *********************************************************************** -->
322<div class="doc_section">
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]323 <a name="whatsnew">What's New in LLVM 2.8?</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]324</div>
325<!-- *********************************************************************** -->
326
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000[diff] [blame]327<div class="doc_text">
328
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]329<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]330minor improvements. Some of the major improvements and new features are listed
331in this section.
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000[diff] [blame]332</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]333
Chris Lattnera67df2d2010-04-22 06:28:20 +0000[diff] [blame]334</div>
335
336<!--=========================================================================-->
337<div class="doc_subsection">
338<a name="orgchanges">LLVM Community Changes</a>
339</div>
340
341<div class="doc_text">
342
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]343<p>In addition to changes to the code, between LLVM 2.7 and 2.8, a number of
Chris Lattner87e04952010-04-21 05:17:40 +0000[diff] [blame]344organization changes have happened:
345</p>
346
347<ul>
Chris Lattner342f9572010-09-29 05:30:03 +0000[diff] [blame]348<li>libc++ and lldb are new</li>
Chris Lattner16be34d2010-09-29 07:25:03 +0000[diff] [blame]349<li>Debugging optimized code support.</li>
Chris Lattner87e04952010-04-21 05:17:40 +0000[diff] [blame]350</ul>
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000[diff] [blame]351</div>
352
Chris Lattnerc75fd522008-06-08 21:58:17 +0000[diff] [blame]353<!--=========================================================================-->
Chris Lattner625a3d82008-06-08 21:34:41 +0000[diff] [blame]354<div class="doc_subsection">
Chris Lattnercdc44ed2008-02-06 18:00:06 +0000[diff] [blame]355<a name="majorfeatures">Major New Features</a>
356</div>
357
358<div class="doc_text">
359
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]360<p>LLVM 2.8 includes several major new capabilities:</p>
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]361
362<ul>
Chris Lattner8c26cee2010-09-05 20:49:45 +0000[diff] [blame]363<li>atomic lowering pass.</li>
364<li>RegionInfo pass: opt -regions analyze" or "opt -view-regions".
365<!-- Tobias Grosser --></li>
366<li>ARMGlobalMerge: <!-- Anton --> </li>
Chris Lattner8128ca12010-09-06 19:14:40 +0000[diff] [blame]367<li>llvm-diff</li>
Chris Lattner458e79f2008-02-10 08:18:42 +0000[diff] [blame]368</ul>
Chris Lattner10a3cc42010-03-17 06:41:58 +0000[diff] [blame]369
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]370</div>
371
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]372<!--=========================================================================-->
373<div class="doc_subsection">
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]374<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000[diff] [blame]375</div>
376
377<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]378<p>LLVM IR has several new features for better support of new targets and that
379expose new optimization opportunities:</p>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000[diff] [blame]380
Chris Lattnerb7112222008-06-05 06:25:56 +0000[diff] [blame]381<ul>
Gabor Greif4b17e652010-07-21 10:20:08 +0000[diff] [blame]382
383<li>LLVM 2.8 changes the internal order of operands in <a
384 href="http://llvm.org/doxygen/classllvm_1_1InvokeInst.html"><tt>InvokeInst</tt></a>
385 and <a href="http://llvm.org/doxygen/classllvm_1_1CallInst.html"><tt>CallInst</tt></a>.
386 To be portable across releases, resort to <tt>CallSite</tt> and the
Gabor Greif930894f2010-07-21 10:22:41 +0000[diff] [blame]387 high-level accessors, such as <tt>getCalledValue</tt> and <tt>setUnwindDest</tt>.
Gabor Greif4b17e652010-07-21 10:20:08 +0000[diff] [blame]388</li>
Gabor Greifed79dcb2010-07-26 18:48:07 +0000[diff] [blame]389<li>
390 You can no longer pass use_iterators directly to cast<> (and similar), because
391 these routines tend to perform costly dereference operations more than once. You
392 have to dereference the iterators yourself and pass them in.
393</li>
Torok Edwine6f478f2010-08-04 12:43:22 +0000[diff] [blame]394<li>
395 llvm.memcpy.*, llvm.memset.*, llvm.memmove.* (and possibly other?) intrinsics
396 take an extra parameter now (i1 isVolatile), totaling 5 parameters.
397 If you were creating these intrinsic calls and prototypes yourself (as opposed
398 to using Intrinsic::getDeclaration), you can use UpgradeIntrinsicFunction/UpgradeIntrinsicCall
399 to be portable accross releases.
400 Note that you cannot use Intrinsic::getDeclaration() in a backwards compatible
401 way (needs 2/3 types now, in 2.7 it needed just 1).
402</li>
403<li>
404 SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode.
405 Change your code to use
406 SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)).
407</li>
408<li>
409 VISIBILITY_HIDDEN is gone.
410</li>
411<li>
Owen Andersonf16eb372010-08-04 18:27:08 +0000[diff] [blame]412 The <tt>RegisterPass</tt> and <tt>RegisterAnalysisGroup</tt> templates are
413 considered deprecated, but continue to function in LLVM 2.8. Clients are
414 strongly advised to use the upcoming <tt>INITIALIZE_PASS()</tt> and
415 <tt>INITIALIZE_AG_PASS()</tt> macros instead.
416<li>
Torok Edwine6f478f2010-08-04 12:43:22 +0000[diff] [blame]417 SMDiagnostic takes different parameters now. //FIXME: how to upgrade?
418</li>
419<li>
Duncan Sands1b6744a2010-08-30 10:57:54 +0000[diff] [blame]420 The constructor for the Triple class no longer tries to understand odd triple
421 specifications. Frontends should ensure that they only pass valid triples to
422 LLVM. The Triple::normalize utility method has been added to help front-ends
423 deal with funky triples.
424<li>
Torok Edwine6f478f2010-08-04 12:43:22 +0000[diff] [blame]425 Some APIs got renamed:
426 <ul>
427 <li>llvm_report_error -&gt; report_fatal_error</li>
428 <li>llvm_install_error_handler -&gt; install_fatal_error_handler</li>
429 <li>llvm::DwarfExceptionHandling -&gt; llvm::JITExceptionHandling</li>
430 </ul>
431</li>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000[diff] [blame]432</ul>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +0000[diff] [blame]433
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000[diff] [blame]434</div>
435
436<!--=========================================================================-->
437<div class="doc_subsection">
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000[diff] [blame]438<a name="optimizer">Optimizer Improvements</a>
439</div>
440
441<div class="doc_text">
442
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]443<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattner25879d72008-10-13 21:50:36 +0000[diff] [blame]444release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000[diff] [blame]445
446<ul>
447
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]448<li></li>
Chris Lattnera668b452010-04-21 06:42:24 +0000[diff] [blame]449
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]450</ul>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]451
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]452</div>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]453
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]454
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]455<!--=========================================================================-->
456<div class="doc_subsection">
457<a name="executionengine">Interpreter and JIT Improvements</a>
458</div>
Chris Lattner25879d72008-10-13 21:50:36 +0000[diff] [blame]459
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]460<div class="doc_text">
461
462<ul>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]463<li></li>
Chris Lattner87e04952010-04-21 05:17:40 +0000[diff] [blame]464
Chris Lattner7795ea92008-06-08 02:45:07 +0000[diff] [blame]465</ul>
466
467</div>
468
469<!--=========================================================================-->
470<div class="doc_subsection">
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000[diff] [blame]471<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner7795ea92008-06-08 02:45:07 +0000[diff] [blame]472</div>
473
474<div class="doc_text">
475
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000[diff] [blame]476<p>We have put a significant amount of work into the code generator
477infrastructure, which allows us to implement more aggressive algorithms and make
478it run faster:</p>
Chris Lattner7795ea92008-06-08 02:45:07 +0000[diff] [blame]479
480<ul>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]481<li>MachO writer works.</li>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]482</ul>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]483</div>
484
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]485<!--=========================================================================-->
486<div class="doc_subsection">
487<a name="x86">X86-32 and X86-64 Target Improvements</a>
488</div>
489
490<div class="doc_text">
491<p>New features of the X86 target include:
492</p>
493
494<ul>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]495<li>The X86 backend now supports holding X87 floating point stack values
496 in registers across basic blocks, dramatically improving performance of code
497 that uses long double, and when targetting CPUs that don't support SSE.</li>
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000[diff] [blame]498
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]499</ul>
500
Chris Lattnerd1094e02009-03-02 02:37:32 +0000[diff] [blame]501</div>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000[diff] [blame]502
503<!--=========================================================================-->
504<div class="doc_subsection">
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]505<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000[diff] [blame]506</div>
507
508<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]509<p>New features of the ARM target include:
510</p>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000[diff] [blame]511
512<ul>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000[diff] [blame]513
Bob Wilson46d65802010-09-13 17:37:55 +0000[diff] [blame]514<li>
515 All of the NEON load and store intrinsics (llvm.arm.neon.vld* and
516 llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes
517 of the memory being accessed.
518</li>
519<li>
520 The llvm.arm.neon.vaba intrinsic (vector absolute difference and
521 accumulate) has been removed. This operation is now represented using
522 the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a
523 vector add.
Bob Wilsone44f2982010-09-13 17:39:35 +0000[diff] [blame]524</li>
Bob Wilson46d65802010-09-13 17:37:55 +0000[diff] [blame]525<li>
526 The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening
527 vector absolute difference with and without accumlation) have been removed.
528 They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute
529 difference) followed by a vector zero-extend operation, and for vabal,
530 a vector add.
531</li>
532<li>
533 The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic
534 are now replaced by vector truncate operations.
535</li>
536<li>
537 The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been
538 removed. They are now represented as vector sign-extend (vmovls) and
539 zero-extend (vmovlu) operations.
540</li>
541<li>
542 The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and
543 llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have
544 been removed. They are replaced by vector add and vector subtract operations
545 where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either
546 sign-extended or zero-extended.
547</li>
548<li>
549 The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and
550 llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without
551 accumulation and subtraction) have been removed. These operations are now
552 represented as vector multiplications where the operands are either
553 sign-extended or zero-extended, followed by a vector add for vmlal or a
554 vector subtract for vmlsl. Note that the polynomial vector multiply
555 intrinsic, llvm.arm.neon.vmullp, remains unchanged.
556</li>
Bob Wilsone44f2982010-09-13 17:39:35 +0000[diff] [blame]557
558</ul>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]559</div>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000[diff] [blame]560
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]561<!--=========================================================================-->
562<div class="doc_subsection">
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]563<a name="newapis">New Useful APIs</a>
564</div>
565
566<div class="doc_text">
567
568<p>This release includes a number of new APIs that are used internally, which
569 may also be useful for external clients.
570</p>
571
572<ul>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]573<li></li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]574</ul>
575
576
577</div>
578
579<!--=========================================================================-->
580<div class="doc_subsection">
581<a name="otherimprovements">Other Improvements and New Features</a>
582</div>
583
584<div class="doc_text">
585<p>Other miscellaneous features include:</p>
586
587<ul>
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]588<li></li>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000[diff] [blame]589</ul>
590
591</div>
592
Chris Lattner6cb64032008-06-05 08:02:49 +0000[diff] [blame]593
594<!--=========================================================================-->
595<div class="doc_subsection">
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]596<a name="changes">Major Changes and Removed Features</a>
597</div>
598
599<div class="doc_text">
600
Chris Lattner934e2d42008-10-13 22:06:31 +0000[diff] [blame]601<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]602on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading
Chris Lattner934e2d42008-10-13 22:06:31 +0000[diff] [blame]603from the previous release.</p>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]604
605<ul>
Chris Lattnerfc561ba2010-09-02 23:22:50 +0000[diff] [blame]606<li>.ll file doesn't produce #uses comments anymore, to get them, run a .bc file
607 through "llvm-dis --show-annotations".</li>
Chris Lattnerbd244042010-08-28 16:33:36 +0000[diff] [blame]608<li>MSIL Backend removed.</li>
609<li>ABCD and SSI passes removed.</li>
610<li>'Union' LLVM IR feature removed.</li>
Chris Lattner87e04952010-04-21 05:17:40 +0000[diff] [blame]611</ul>
Chris Lattner934e2d42008-10-13 22:06:31 +0000[diff] [blame]612
613<p>In addition, many APIs have changed in this release. Some of the major LLVM
614API changes are:</p>
615
616<ul>
Devang Pateldbf83832008-10-14 20:03:43 +0000[diff] [blame]617</ul>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]618
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000[diff] [blame]619</div>
620
621
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]622<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]623<div class="doc_section">
624 <a name="knownproblems">Known Problems</a>
625</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]626<!-- *********************************************************************** -->
627
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]628<div class="doc_text">
629
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000[diff] [blame]630<p>This section contains significant known problems with the LLVM system,
Chris Lattner2a092392008-11-10 05:40:34 +0000[diff] [blame]631listed by component. If you run into a problem, please check the <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]632href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]633there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]634
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]635</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]636
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]637<!-- ======================================================================= -->
638<div class="doc_subsection">
639 <a name="experimental">Experimental features included with this release</a>
640</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]641
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]642<div class="doc_text">
643
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]644<p>The following components of this LLVM release are either untested, known to
645be broken or unreliable, or are in early development. These components should
646not be relied on, and bugs should not be filed against them, but they may be
647useful to some people. In particular, if you would like to work on one of these
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]648components, please contact us on the <a
649href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]650
651<ul>
Chris Lattnerbd244042010-08-28 16:33:36 +0000[diff] [blame]652<li>The Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
Wesley Peck3aa84e52010-03-18 14:31:30 +0000[diff] [blame]653 backends are experimental.</li>
Chris Lattnera67df2d2010-04-22 06:28:20 +0000[diff] [blame]654<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattnerb3fa6bf2010-07-21 15:57:40 +0000[diff] [blame]655 supported value for this option. XXX Update me</li>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]656</ul>
657
658</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]659
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]660<!-- ======================================================================= -->
661<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]662 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswell3bdbd302005-11-08 21:11:33 +0000[diff] [blame]663</div>
664
665<div class="doc_text">
666
667<ul>
Anton Korobeynikov486c7d32008-06-08 10:24:13 +0000[diff] [blame]668 <li>The X86 backend does not yet support
669 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
670 floating point stack</a>. It supports the 'f' and 't' constraints, but not
671 'u'.</li>
Duncan Sands0bc15262008-06-08 19:38:43 +0000[diff] [blame]672 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellea03c9d2009-03-02 15:28:15 +0000[diff] [blame]673 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattnera67df2d2010-04-22 06:28:20 +0000[diff] [blame]674 runtime currently due to lack of support for the 'u' inline assembly
675 constraint and for X87 floating point inline assembly.</li>
Dan Gohman721b3722008-06-08 23:05:11 +0000[diff] [blame]676 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattnera67df2d2010-04-22 06:28:20 +0000[diff] [blame]677 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman721b3722008-06-08 23:05:11 +0000[diff] [blame]678 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]679</ul>
680
681</div>
682
683<!-- ======================================================================= -->
684<div class="doc_subsection">
685 <a name="ppc-be">Known problems with the PowerPC back-end</a>
686</div>
687
688<div class="doc_text">
689
690<ul>
Nicolas Geoffray77d99502007-05-15 09:21:28 +0000[diff] [blame]691<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattnerbee7b322007-05-23 04:39:32 +0000[diff] [blame]692compilation, and lacks support for debug information.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]693</ul>
694
695</div>
696
697<!-- ======================================================================= -->
698<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]699 <a name="arm-be">Known problems with the ARM back-end</a>
700</div>
701
702<div class="doc_text">
703
704<ul>
Chris Lattnerbee7b322007-05-23 04:39:32 +0000[diff] [blame]705<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands47fc0a22007-09-26 15:59:54 +0000[diff] [blame]706processors, thumb programs can crash or produce wrong
Chris Lattnerbee7b322007-05-23 04:39:32 +0000[diff] [blame]707results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellea03c9d2009-03-02 15:28:15 +0000[diff] [blame]708<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]709</li>
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]710</ul>
711
712</div>
713
714<!-- ======================================================================= -->
715<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]716 <a name="sparc-be">Known problems with the SPARC back-end</a>
717</div>
718
719<div class="doc_text">
720
721<ul>
John Criswellea03c9d2009-03-02 15:28:15 +0000[diff] [blame]722<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]723 support the 64-bit SPARC ABI (-m64).</li>
724</ul>
725
726</div>
727
728<!-- ======================================================================= -->
729<div class="doc_subsection">
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000[diff] [blame]730 <a name="mips-be">Known problems with the MIPS back-end</a>
731</div>
732
733<div class="doc_text">
734
735<ul>
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000[diff] [blame]736<li>64-bit MIPS targets are not supported yet.</li>
737</ul>
738
739</div>
740
741<!-- ======================================================================= -->
742<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]743 <a name="alpha-be">Known problems with the Alpha back-end</a>
744</div>
745
746<div class="doc_text">
747
748<ul>
749
750<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
751appropriate nops inserted to ensure restartability.</li>
752
John Criswell3bdbd302005-11-08 21:11:33 +0000[diff] [blame]753</ul>
754</div>
755
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]756<!-- ======================================================================= -->
757<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000[diff] [blame]758 <a name="c-be">Known problems with the C back-end</a>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]759</div>
760
761<div class="doc_text">
762
Chris Lattner086d2692010-09-29 05:34:42 +0000[diff] [blame]763<p>The C backend has numerous problems and is not being actively maintained.
764Depending on it for anything serious is not advised.</p>
765
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]766<ul>
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000[diff] [blame]767<li><a href="http://llvm.org/PR802">The C backend has only basic support for
768 inline assembly code</a>.</li>
Chris Lattner8e061162007-09-26 06:01:35 +0000[diff] [blame]769<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
770 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif75b2f762009-03-02 12:02:51 +0000[diff] [blame]771 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandse09506a2008-02-10 13:40:55 +0000[diff] [blame]772<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands3aa36732009-02-25 11:51:54 +0000[diff] [blame]773<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000[diff] [blame]774</ul>
775
776</div>
John Criswell3bdbd302005-11-08 21:11:33 +0000[diff] [blame]777
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]778
779<!-- ======================================================================= -->
780<div class="doc_subsection">
Chris Lattner086d2692010-09-29 05:34:42 +0000[diff] [blame]781 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]782</div>
Chris Lattner178f3db2003-10-02 05:07:23 +0000[diff] [blame]783
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]784<div class="doc_text">
Chris Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]785
Chris Lattner086d2692010-09-29 05:34:42 +0000[diff] [blame]786<p>llvm-gcc is generally very stable for the C family of languages. The only
787 major language feature of GCC not supported by llvm-gcc is the
788 <tt>__builtin_apply</tt> family of builtins. However, some extensions
789 are only supported on some targets. For example, trampolines are only
790 supported on some targets (these are used when you take the address of a
791 nested function).</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]792
Chris Lattner086d2692010-09-29 05:34:42 +0000[diff] [blame]793<p>Fortran support generally works, but there are still several unresolved bugs
794 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
795 tools/gfortran component for details. Note that llvm-gcc is missing major
796 Fortran performance work in the frontend and library that went into GCC after
797 4.2. If you are interested in Fortran, we recommend that you consider using
798 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]799
Chris Lattner086d2692010-09-29 05:34:42 +0000[diff] [blame]800<p>The llvm-gcc 4.2 Ada compiler has basic functionality. However, this is not a
801mature technology, and problems should be expected. For example:</p>
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]802<ul>
Duncan Sands56448462008-06-08 20:18:35 +0000[diff] [blame]803<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswellea03c9d2009-03-02 15:28:15 +0000[diff] [blame]804to lack of trampoline support (pointers to nested functions) on other platforms.
805However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]806which does support trampolines.</li>
807<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sandsd34bf762009-02-25 11:59:06 +0000[diff] [blame]808This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
809exception handling, which is used internally by the compiler.
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]810Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sandsaef747f2008-10-13 17:27:23 +0000[diff] [blame]811<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
812and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsd34bf762009-02-25 11:59:06 +0000[diff] [blame]813(c380004 also fails with gcc-4.2 mainline).
814If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
815causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sands2dbb00e2009-03-02 16:35:57 +0000[diff] [blame]816<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]817<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]818<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattneraa61f412009-10-13 17:48:04 +0000[diff] [blame]819crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]820<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
821or finish at a non-byte offset</a> in a record. Workaround: do not pack records
822or use representation clauses that result in a field of a non-discrete type
823starting or finishing in the middle of a byte.</li>
Chris Lattnerb076b002008-06-08 21:19:07 +0000[diff] [blame]824<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
825'main' as generated by the Ada binder to be invalid</a>.
826Workaround: hand edit the file to use pointers for <tt>argv</tt> and
827<tt>envp</tt> rather than integers.</li>
828<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
829ignored</a>.</li>
Chris Lattnere38ac152008-02-12 06:29:45 +0000[diff] [blame]830</ul>
831</div>
832
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]833<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]834<div class="doc_section">
835 <a name="additionalinfo">Additional Information</a>
836</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]837<!-- *********************************************************************** -->
838
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]839<div class="doc_text">
840
Chris Lattnercb5596d2005-05-16 17:13:10 +0000[diff] [blame]841<p>A wide variety of additional information is available on the <a
Chris Lattnere0c1df42007-05-18 00:44:29 +0000[diff] [blame]842href="http://llvm.org">LLVM web page</a>, in particular in the <a
843href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencerc7f87f22007-07-09 08:04:31 +0000[diff] [blame]844contains versions of the API documentation which is up-to-date with the
845Subversion version of the source code.
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]846You can access versions of these documents specific to this release by going
847into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]848
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]849<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]850us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]851lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]852
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]853</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]854
855<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]856
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]857<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]858<address>
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Misha Brukman86242e12008-12-11 17:34:48 +0000[diff] [blame]860 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
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Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]863
Chris Lattnere0c1df42007-05-18 00:44:29 +0000[diff] [blame]864 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]865 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]866</address>
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Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]868</body>
869</html>