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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
<title>LLVM 3.0 Release Notes</title>
</head>
<body>
<h1>LLVM 3.0 Release Notes</h1>
<img align=right src="http://llvm.org/img/DragonSmall.png"
width="136" height="136" alt="LLVM Dragon Logo">
<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#subproj">Sub-project Status Update</a></li>
<li><a href="#externalproj">External Projects Using LLVM 3.0</a></li>
<li><a href="#whatsnew">What's New in LLVM 3.0?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#knownproblems">Known Problems</a></li>
<li><a href="#additionalinfo">Additional Information</a></li>
</ol>
<div class="doc_author">
<p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
</div>
<!--
<h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.0
release.<br>
You may prefer the
<a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9
Release Notes</a>.</h1>
-->
<!-- *********************************************************************** -->
<h2>
<a name="intro">Introduction</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>This document contains the release notes for the LLVM Compiler
Infrastructure, release 3.0. Here we describe the status of LLVM, including
major improvements from the previous release and significant known problems.
All LLVM releases may be downloaded from
the <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
<p>For more information about LLVM, including information about the latest
release, please check out the <a href="http://llvm.org/">main LLVM web
site</a>. If you have questions or comments,
the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM
Developer's Mailing List</a> is a good place to send them.</p>
<p>Note that if you are reading this file from a Subversion checkout or the main
LLVM web page, this document applies to the <i>next</i> release, not the
current one. To see the release notes for a specific release, please see the
<a href="http://llvm.org/releases/">releases page</a>.</p>
</div>
<!-- Features that need text if they're finished for 3.1:
ARM EHABI
combiner-aa?
strong phi elim
loop dependence analysis
CorrelatedValuePropagation
lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
-->
<!-- *********************************************************************** -->
<h2>
<a name="subproj">Sub-project Status Update</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>The LLVM 3.0 distribution currently consists of code from the core LLVM
repository (which roughly includes the LLVM optimizers, code generators and
supporting tools), the Clang repository and the llvm-gcc repository. In
addition to this code, the LLVM Project includes other sub-projects that are
in development. Here we include updates on these subprojects.</p>
<!--=========================================================================-->
<h3>
<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
</h3>
<div>
<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
C++, and Objective-C languages. Clang aims to provide a better user
experience through expressive diagnostics, a high level of conformance to
language standards, fast compilation, and low memory use. Like LLVM, Clang
provides a modular, library-based architecture that makes it suitable for
creating or integrating with other development tools. Clang is considered a
production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
(32- and 64-bit), and for darwin/arm targets.</p>
<p>In the LLVM 3.0 time-frame, the Clang team has made many improvements:</p>
<ul>
<li>Greatly improved support for building C++ applications, with greater
stability and better diagnostics.</li>
<li><a href="http://clang.llvm.org/cxx_status.html">Improved support</a> for
the <a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50372">C++
2011</a> standard, including implementations of non-static data member
initializers, alias templates, delegating constructors, the range-based
for loop, and implicitly-generated move constructors and move assignment
operators, among others.</li>
<li>Implemented support for some features of the upcoming C1x standard,
including static assertions and generic selections.</li>
<li>Better detection of include and linking paths for system headers and
libraries, especially for Linux distributions.</li>
<li>Implemented support
for <a href="http://clang.llvm.org/docs/AutomaticReferenceCounting.html">Automatic
Reference Counting</a> for Objective-C.</li>
<li>Implemented a number of optimizations in <tt>libclang</tt>, the Clang C
interface, to improve the performance of code completion and the mapping
from source locations to abstract syntax tree nodes.</li>
</ul>
<p>If Clang rejects your code but another compiler accepts it, please take a
look at the <a href="http://clang.llvm.org/compatibility.html">language
compatibility</a> guide to make sure this is not intentional or a known
issue.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
</h3>
<div>
<p><a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
optimizers and code generators with LLVM's. Currently it requires a patched
version of gcc-4.5. The plugin can target the x86-32 and x86-64 processor
families and has been used successfully on the Darwin, FreeBSD and Linux
platforms. The Ada, C, C++ and Fortran languages work well. The plugin is
capable of compiling plenty of Obj-C, Obj-C++ and Java but it is not known
whether the compiled code actually works or not!</p>
<p>The 3.0 release has the following notable changes:</p>
<ul>
<!--
<li></li>
-->
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
</h3>
<div>
<p>The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
is a simple library that provides an implementation of the low-level
target-specific hooks required by code generation and other runtime
components. For example, when compiling for a 32-bit target, converting a
double to a 64-bit unsigned integer is compiled into a runtime call to the
"__fixunsdfdi" function. The compiler-rt library provides highly optimized
implementations of this and other low-level routines (some are 3x faster than
the equivalent libgcc routines).</p>
<p>In the LLVM 3.0 timeframe,</p>
</div>
<!--=========================================================================-->
<h3>
<a name="lldb">LLDB: Low Level Debugger</a>
</h3>
<div>
<p><a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
umbrella of projects. LLDB is a next generation, high-performance
debugger. It is built as a set of reusable components which highly leverage
existing libraries in the larger LLVM Project, such as the Clang expression
parser, the LLVM disassembler and the LLVM JIT.</p>
<p>LLDB is has advanced by leaps and bounds in the 3.0 timeframe. It is
dramatically more stable and useful, and includes both a
new <a href="http://lldb.llvm.org/tutorial.html">tutorial</a> and
a <a href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with
GDB</a>.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="libc++">libc++: C++ Standard Library</a>
</h3>
<div>
<p><a href="http://libcxx.llvm.org/">libc++</a> is another new member of the
LLVM family. It is an implementation of the C++ standard library, written
from the ground up to specifically target the forthcoming C++'0X standard and
focus on delivering great performance.</p>
<p>In the LLVM 3.0 timeframe,</p>
<p>Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
licensed</a> under the MIT and UIUC license, allowing it to be used more
permissively.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="LLBrowse">LLBrowse: IR Browser</a>
</h3>
<div>
<p><a href="http://llvm.org/svn/llvm-project/llbrowse/trunk/doc/LLBrowse.html">
LLBrowse</a> is an interactive viewer for LLVM modules. It can load any LLVM
module and displays its contents as an expandable tree view, facilitating an
easy way to inspect types, functions, global variables, or metadata nodes. It
is fully cross-platform, being based on the popular wxWidgets GUI
toolkit.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="vmkit">VMKit</a>
</h3>
<div>
<p>The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation
of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
just-in-time compilation. As of LLVM 3.0, VMKit now supports generational
garbage collectors. The garbage collectors are provided by the MMTk
framework, and VMKit can be configured to use one of the numerous implemented
collectors of MMTk.</p>
</div>
<!--=========================================================================-->
<!--
<h3>
<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
</h3>
<div>
<p>
<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
through the application and records state transitions that lead to fault
states. This allows it to construct testcases that lead to faults and can even
be used to verify some algorithms.
</p>
<p>UPDATE!</p>
</div>-->
</div>
<!-- *********************************************************************** -->
<h2>
<a name="externalproj">External Open Source Projects Using LLVM 3.0</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>An exciting aspect of LLVM is that it is used as an enabling technology for
a lot of other language and tools projects. This section lists some of the
projects that have already been updated to work with LLVM 3.0.</p>
<!--=========================================================================-->
<h3>Crack Programming Language</h3>
<div>
<p><a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide
the ease of development of a scripting language with the performance of a
compiled language. The language derives concepts from C++, Java and Python,
incorporating object-oriented programming, operator overloading and strong
typing.</p>
</div>
<!--=========================================================================-->
<h3>TTA-based Codesign Environment (TCE)</h3>
<div>
<p>TCE is a toolset for designing application-specific processors (ASP) based on
the Transport triggered architecture (TTA). The toolset provides a complete
co-design flow from C/C++ programs down to synthesizable VHDL and parallel
program binaries. Processor customization points include the register files,
function units, supported operations, and the interconnection network.</p>
<p>TCE uses Clang and LLVM for C/C++ language support, target independent
optimizations and also for parts of code generation. It generates new
LLVM-based code generators "on the fly" for the designed TTA processors and
loads them in to the compiler backend as runtime libraries to avoid
per-target recompilation of larger parts of the compiler chain.</p>
</div>
<!--=========================================================================-->
<h3>PinaVM</h3>
<div>
<p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open
source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many
other front-ends, PinaVM actually executes the elaboration of the program
analyzed using LLVM's JIT infrastructure. It later enriches the bitcode with
SystemC-specific information.</p>
</div>
<!--=========================================================================-->
<h3>Pure</h3>
<div>
<p><a href="http://pure-lang.googlecode.com/">Pure</a> is an
algebraic/functional programming language based on term rewriting. Programs
are collections of equations which are used to evaluate expressions in a
symbolic fashion. The interpreter uses LLVM as a backend to JIT-compile Pure
programs to fast native code. Pure offers dynamic typing, eager and lazy
evaluation, lexical closures, a hygienic macro system (also based on term
rewriting), built-in list and matrix support (including list and matrix
comprehensions) and an easy-to-use interface to C and other programming
languages (including the ability to load LLVM bitcode modules, and inline C,
C++, Fortran and Faust code in Pure programs if the corresponding
LLVM-enabled compilers are installed).</p>
<p>Pure version 0.47 has been tested and is known to work with LLVM 3.0 (and
continues to work with older LLVM releases >= 2.5).</p>
</div>
<!--=========================================================================-->
<h3 id="icedtea">IcedTea Java Virtual Machine Implementation</h3>
<div>
<p><a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
harness to build OpenJDK using only free software build tools and to provide
replacements for the not-yet free parts of OpenJDK. One of the extensions
that IcedTea provides is a new JIT compiler
named <a href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a>
which uses LLVM to provide native code generation without introducing
processor-dependent code.</p>
<p>OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested and
are known to work with LLVM 3.0 (and continue to work with older LLVM
releases >= 2.6 as well).</p>
</div>
<!--=========================================================================-->
<h3>Glasgow Haskell Compiler (GHC)</h3>
<div>
<p>GHC is an open source, state-of-the-art programming suite for Haskell, a
standard lazy functional programming language. It includes an optimizing
static compiler generating good code for a variety of platforms, together
with an interactive system for convenient, quick development.</p>
<p>In addition to the existing C and native code generators, GHC 7.0 now
supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p>
</div>
<!--=========================================================================-->
<h3>Polly - Polyhedral optimizations for LLVM</h3>
<div>
<p>Polly is a project that aims to provide advanced memory access optimizations
to better take advantage of SIMD units, cache hierarchies, multiple cores or
even vector accelerators for LLVM. Built around an abstract mathematical
description based on Z-polyhedra, it provides the infrastructure to develop
advanced optimizations in LLVM and to connect complex external optimizers. In
its first year of existence Polly already provides an exact value-based
dependency analysis as well as basic SIMD and OpenMP code generation support.
Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for
data-locality and parallelism.</p>
</div>
<!--=========================================================================-->
<h3>Rubinius</h3>
<div>
<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
for running Ruby code which strives to write as much of the implementation in
Ruby as possible. Combined with a bytecode interpreting VM, it uses LLVM to
optimize and compile ruby code down to machine code. Techniques such as type
feedback, method inlining, and deoptimization are all used to remove dynamism
from ruby execution and increase performance.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a>
</h3>
<div>
<p><a href="http://faust.grame.fr">FAUST</a> is a compiled language for
real-time audio signal processing. The name FAUST stands for Functional AUdio
STream. Its programming model combines two approaches: functional programming
and block diagram composition. In addition with the C, C++, JAVA output
formats, the Faust compiler can now generate LLVM bitcode, and works with
LLVM 2.7-3.0.</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2>
<a name="whatsnew">What's New in LLVM 3.0?</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>This release includes a huge number of bug fixes, performance tweaks and
minor improvements. Some of the major improvements and new features are
listed in this section.</p>
<!--=========================================================================-->
<h3>
<a name="majorfeatures">Major New Features</a>
</h3>
<div>
<p>LLVM 3.0 includes several major new capabilities:</p>
<ul>
<!--
<li></li>
-->
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="coreimprovements">LLVM IR and Core Improvements</a>
</h3>
<div>
<p>LLVM IR has several new features for better support of new targets and that
expose new optimization opportunities:</p>
<p>One of the biggest changes is that 3.0 has a new exception handling
system. The old system used LLVM intrinsics to convey the exception handling
information to the code generator. It worked in most cases, but not
all. Inlining was especially difficult to get right. Also, the intrinsics
could be moved away from the <code>invoke</code> instruction, making it hard
to recover that information.</p>
<p>The new EH system makes exception handling a first-class member of the IR. It
adds two new instructions:</p>
<ul>
<li><a href="LangRef.html#i_landingpad"><code>landingpad</code></a> —
this instruction defines a landing pad basic block. It contains all of the
information that's needed by the code generator. It's also required to be
the first non-PHI instruction in the landing pad. In addition, a landing
pad may be jumped to only by the unwind edge of an <code>invoke</code>
instruction.</li>
<li><a href="LangRef.html#i_resume"><code>resume</code></a> — this
instruction causes the current exception to resume traveling up the
stack. It replaces the <code>@llvm.eh.resume</code> intrinsic.</li>
</ul>
<p>Converting from the old EH API to the new EH API is rather simple, because a
lot of complexity has been removed. The two intrinsics,
<code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code> have been
superceded by the <code>landingpad</code> instruction. Instead of generating
a call to <code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code>:
<div class="doc_code">
<pre>
Function *ExcIntr = Intrinsic::getDeclaration(TheModule,
Intrinsic::eh_exception);
Function *SlctrIntr = Intrinsic::getDeclaration(TheModule,
Intrinsic::eh_selector);
// The exception pointer.
Value *ExnPtr = Builder.CreateCall(ExcIntr, "exc_ptr");
std::vector<Value*> Args;
Args.push_back(ExnPtr);
Args.push_back(Builder.CreateBitCast(Personality,
Type::getInt8PtrTy(Context)));
<i>// Add selector clauses to Args.</i>
// The selector call.
Builder.CreateCall(SlctrIntr, Args, "exc_sel");
</pre>
</div>
<p>You should instead generate a <code>landingpad</code> instruction, that
returns an exception object and selector value:</p>
<div class="doc_code">
<pre>
LandingPadInst *LPadInst =
Builder.CreateLandingPad(StructType::get(Int8PtrTy, Int32Ty, NULL),
Personality, 0);
Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0);
Builder.CreateStore(LPadExn, getExceptionSlot());
Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1);
Builder.CreateStore(LPadSel, getEHSelectorSlot());
</pre>
</div>
<p>It's now trivial to add the individual clauses to the <code>landingpad</code>
instruction.</p>
<div class="doc_code">
<pre>
<i><b>// Adding a catch clause</b></i>
Constant *TypeInfo = getTypeInfo();
LPadInst->addClause(TypeInfo);
<i><b>// Adding a C++ catch-all</b></i>
LPadInst->addClause(Constant::getNullValue(Builder.getInt8PtrTy()));
<i><b>// Adding a cleanup</b></i>
LPadInst->setCleanup(true);
<i><b>// Adding a filter clause</b></i>
std::vector<Constant*> TypeInfos;
Constant *TypeInfo = getFilterTypeInfo();
TypeInfos.push_back(Builder.CreateBitCast(TypeInfo, Builder.getInt8PtrTy()));
ArrayType *FilterTy = ArrayType::get(Int8PtrTy, TypeInfos.size());
LPadInst->addClause(ConstantArray::get(FilterTy, TypeInfos));
</pre>
</div>
<p>Converting from using the <code>@llvm.eh.resume</code> intrinsic to
the <code>resume</code> instruction is trivial. It takes the exception
pointer and exception selector values returned by
the <code>landingpad</code> instruction:</p>
<div class="doc_code">
<pre>
Type *UnwindDataTy = StructType::get(Builder.getInt8PtrTy(),
Builder.getInt32Ty(), NULL);
Value *UnwindData = UndefValue::get(UnwindDataTy);
Value *ExcPtr = Builder.CreateLoad(getExceptionObjSlot());
Value *ExcSel = Builder.CreateLoad(getExceptionSelSlot());
UnwindData = Builder.CreateInsertValue(UnwindData, ExcPtr, 0, "exc_ptr");
UnwindData = Builder.CreateInsertValue(UnwindData, ExcSel, 1, "exc_sel");
Builder.CreateResume(UnwindData);
</pre>
</div>
</div>
<!--=========================================================================-->
<h3>
<a name="optimizer">Optimizer Improvements</a>
</h3>
<div>
<p>In addition to a large array of minor performance tweaks and bug fixes, this
release includes a few major enhancements and additions to the
optimizers:</p>
<ul>
<!--
<li></li>
-->
</li>
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="mc">MC Level Improvements</a>
</h3>
<div>
<p>The LLVM Machine Code (aka MC) subsystem was created to solve a number of
problems in the realm of assembly, disassembly, object file format handling,
and a number of other related areas that CPU instruction-set level tools work
in.</p>
<ul>
<!--
<li></li>
-->
</ul>
<p>For more information, please see
the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro
to the LLVM MC Project Blog Post</a>.</p>
</div>
<!--=========================================================================-->
<h3>
<a name="codegen">Target Independent Code Generator Improvements</a>
</h3>
<div>
<p>We have put a significant amount of work into the code generator
infrastructure, which allows us to implement more aggressive algorithms and
make it run faster:</p>
<ul>
<!--
<li></li>
-->
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="x86">X86-32 and X86-64 Target Improvements</a>
</h3>
<div>
<p>New features and major changes in the X86 target include:</p>
<ul>
<li>The CRC32 intrinsics have been renamed. The intrinsics were previously
<code>@llvm.x86.sse42.crc32.[8|16|32]</code>
and <code>@llvm.x86.sse42.crc64.[8|64]</code>. They have been renamed to
<code>@llvm.x86.sse42.crc32.32.[8|16|32]</code> and
<code>@llvm.x86.sse42.crc32.64.[8|64]</code>.</li>
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="ARM">ARM Target Improvements</a>
</h3>
<div>
<p>New features of the ARM target include:</p>
<ul>
<!--
<li></li>
-->
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="OtherTS">Other Target Specific Improvements</a>
</h3>
<div>
<ul>
<!--
<li></li>
-->
</ul>
</div>
<!--=========================================================================-->
<h3>
<a name="changes">Major Changes and Removed Features</a>
</h3>
<div>
<p>If you're already an LLVM user or developer with out-of-tree changes based on
LLVM 2.9, this section lists some "gotchas" that you may run into upgrading
from the previous release.</p>
<ul>
<li>The <code>LLVMC</code> front end code was removed while separating
out language independence.</li>
<li>The <code>LowerSetJmp</code> pass wasn't used effectively by any
target and has been removed.</li>
<li>The old <code>TailDup</code> pass was not used in the standard pipeline
and was unable to update ssa form, so it has been removed.
<li>The syntax of volatile loads and stores in IR has been changed to
"<code>load volatile</code>"/"<code>store volatile</code>". The old
syntax ("<code>volatile load</code>"/"<code>volatile store</code>")
is still accepted, but is now considered deprecated.</li>
</ul>
<h4>Windows (32-bit)</h4>
<div>
<ul>
<li>On Win32(MinGW32 and MSVC), Windows 2000 will not be supported.
Windows XP or higher is required.</li>
</ul>
</div>
</div>
<!--=========================================================================-->
<h3>
<a name="api_changes">Internal API Changes</a>
</h3>
<div>
<p>In addition, many APIs have changed in this release. Some of the major
LLVM API changes are:</p>
<ul>
<li>The biggest and most pervasive change is that llvm::Type's are no longer
returned or accepted as 'const' values. Instead, just pass around
non-const Type's.</li>
<li><code>PHINode::reserveOperandSpace</code> has been removed. Instead, you
must specify how many operands to reserve space for when you create the
PHINode, by passing an extra argument
into <code>PHINode::Create</code>.</li>
<li>PHINodes no longer store their incoming BasicBlocks as operands. Instead,
the list of incoming BasicBlocks is stored separately, and can be accessed
with new functions <code>PHINode::block_begin</code>
and <code>PHINode::block_end</code>.</li>
<li>Various functions now take an <code>ArrayRef</code> instead of either a
pair of pointers (or iterators) to the beginning and end of a range, or a
pointer and a length. Others now return an <code>ArrayRef</code> instead
of a reference to a <code>SmallVector</code>
or <code>std::vector</code>. These include:
<ul>
<!-- Please keep this list sorted. -->
<li><code>CallInst::Create</code></li>
<li><code>ComputeLinearIndex</code> (in <code>llvm/CodeGen/Analysis.h</code>)</li>
<li><code>ConstantArray::get</code></li>
<li><code>ConstantExpr::getExtractElement</code></li>
<li><code>ConstantExpr::getGetElementPtr</code></li>
<li><code>ConstantExpr::getInBoundsGetElementPtr</code></li>
<li><code>ConstantExpr::getIndices</code></li>
<li><code>ConstantExpr::getInsertElement</code></li>
<li><code>ConstantExpr::getWithOperands</code></li>
<li><code>ConstantFoldCall</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li>
<li><code>ConstantFoldInstOperands</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li>
<li><code>ConstantVector::get</code></li>
<li><code>DIBuilder::createComplexVariable</code></li>
<li><code>DIBuilder::getOrCreateArray</code></li>
<li><code>ExtractValueInst::Create</code></li>
<li><code>ExtractValueInst::getIndexedType</code></li>
<li><code>ExtractValueInst::getIndices</code></li>
<li><code>FindInsertedValue</code> (in <code>llvm/Analysis/ValueTracking.h</code>)</li>
<li><code>gep_type_begin</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li>
<li><code>gep_type_end</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li>
<li><code>GetElementPtrInst::Create</code></li>
<li><code>GetElementPtrInst::CreateInBounds</code></li>
<li><code>GetElementPtrInst::getIndexedType</code></li>
<li><code>InsertValueInst::Create</code></li>
<li><code>InsertValueInst::getIndices</code></li>
<li><code>InvokeInst::Create</code></li>
<li><code>IRBuilder::CreateCall</code></li>
<li><code>IRBuilder::CreateExtractValue</code></li>
<li><code>IRBuilder::CreateGEP</code></li>
<li><code>IRBuilder::CreateInBoundsGEP</code></li>
<li><code>IRBuilder::CreateInsertValue</code></li>
<li><code>IRBuilder::CreateInvoke</code></li>
<li><code>MDNode::get</code></li>
<li><code>MDNode::getIfExists</code></li>
<li><code>MDNode::getTemporary</code></li>
<li><code>MDNode::getWhenValsUnresolved</code></li>
<li><code>SimplifyGEPInst</code> (in <code>llvm/Analysis/InstructionSimplify.h</code>)</li>
<li><code>TargetData::getIndexedOffset</code></li>
</ul></li>
<li>All forms of <code>StringMap::getOrCreateValue</code> have been remove
except for the one which takes a <code>StringRef</code>.</li>
<li>The <code>LLVMBuildUnwind</code> function from the C API was removed. The
LLVM <code>unwind</code> instruction has been deprecated for a long time
and isn't used by the current front-ends. So this was removed during the
exception handling rewrite.</li>
<li>The <code>LLVMAddLowerSetJmpPass</code> function from the C API was
removed because the <code>LowerSetJmp</code> pass was removed.</li>
<li>The <code>DIBuilder</code> interface used by front ends to encode
debugging information in the LLVM IR now expects clients to
use <code>DIBuilder::finalize()</code> at the end of translation unit to
complete debugging information encoding.</li>
<li>The way the type system works has been
rewritten: <code>PATypeHolder</code> and <code>OpaqueType</code> are gone,
and all APIs deal with <code>Type*</code> instead of <code>const
Type*</code>. If you need to create recursive structures, then create a
named structure, and use <code>setBody()</code> when all its elements are
built. Type merging and refining is gone too: named structures are not
merged with other structures, even if their layout is identical. (of
course anonymous structures are still uniqued by layout).</li>
<li>TargetSelect.h moved to Support/ from Target/</li>
<li>UpgradeIntrinsicCall no longer upgrades pre-2.9 intrinsic calls (for
example <code>llvm.memset.i32</code>).</li>
<li>It is mandatory to initialize all out-of-tree passes too and their dependencies now with
<code>INITIALIZE_PASS{BEGIN,END,}</code>
and <code>INITIALIZE_{PASS,AG}_DEPENDENCY</code>.</li>
<li>The interface for MemDepResult in MemoryDependenceAnalysis has been
enhanced with new return types Unknown and NonFuncLocal, in addition to
the existing types Clobber, Def, and NonLocal.</li>
</ul>
</div>
</div>
<!-- *********************************************************************** -->
<h2>
<a name="knownproblems">Known Problems</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>This section contains significant known problems with the LLVM system, listed
by component. If you run into a problem, please check
the <a href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</p>
<!-- ======================================================================= -->
<h3>
<a name="experimental">Experimental features included with this release</a>
</h3>
<div>
<p>The following components of this LLVM release are either untested, known to
be broken or unreliable, or are in early development. These components
should not be relied on, and bugs should not be filed against them, but they
may be useful to some people. In particular, if you would like to work on
one of these components, please contact us on
the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev
list</a>.</p>
<ul>
<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ and
XCore backends are experimental.</li>
<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets other
than darwin and ELF X86 systems.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="x86-be">Known problems with the X86 back-end</a>
</h3>
<div>
<ul>
<li>The X86 backend does not yet support
all <a href="http://llvm.org/PR879">inline assembly that uses the X86
floating point stack</a>. It supports the 'f' and 't' constraints, but
not 'u'.</li>
<li>The X86-64 backend does not yet support the LLVM IR instruction
<tt>va_arg</tt>. Currently, front-ends support variadic argument
constructs on X86-64 by lowering them manually.</li>
<li>Windows x64 (aka Win64) code generator has a few issues.
<ul>
<li>llvm-gcc cannot build the mingw-w64 runtime currently due to lack of
support for the 'u' inline assembly constraint and for X87 floating
point inline assembly.</li>
<li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt> due
to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
It is fixed
in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
<li>Miss-aligned MOVDQA might crash your program. It is due to
<a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>, lack
of handling aligned internal globals.</li>
</ul>
</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="ppc-be">Known problems with the PowerPC back-end</a>
</h3>
<div>
<ul>
<li>The Linux PPC32/ABI support needs testing for the interpreter and static
compilation, and lacks support for debug information.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="arm-be">Known problems with the ARM back-end</a>
</h3>
<div>
<ul>
<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
processors, thumb programs can crash or produce wrong results
(<a href="http://llvm.org/PR1388">PR1388</a>).</li>
<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully
tested.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="sparc-be">Known problems with the SPARC back-end</a>
</h3>
<div>
<ul>
<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
support the 64-bit SPARC ABI (-m64).</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="mips-be">Known problems with the MIPS back-end</a>
</h3>
<div>
<ul>
<li>64-bit MIPS targets are not supported yet.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="alpha-be">Known problems with the Alpha back-end</a>
</h3>
<div>
<ul>
<li>On 21164s, some rare FP arithmetic sequences which may trap do not have
the appropriate nops inserted to ensure restartability.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="c-be">Known problems with the C back-end</a>
</h3>
<div>
<p>The C backend has numerous problems and is not being actively maintained.
Depending on it for anything serious is not advised.</p>
<ul>
<li><a href="http://llvm.org/PR802">The C backend has only basic support for
inline assembly code</a>.</li>
<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
C++ programs</a>, preventing intermixing between C++ compiled by the CBE
and C++ code compiled with <tt>llc</tt> or native compilers.</li>
<li>The C backend does not support all exception handling constructs.</li>
<li>The C backend does not support arbitrary precision integers.</li>
</ul>
</div>
<!-- ======================================================================= -->
<h3>
<a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
</h3>
<div>
<p><b>LLVM 2.9 was the last release of llvm-gcc.</b></p>
<p>llvm-gcc is generally very stable for the C family of languages. The only
major language feature of GCC not supported by llvm-gcc is the
<tt>__builtin_apply</tt> family of builtins. However, some extensions
are only supported on some targets. For example, trampolines are only
supported on some targets (these are used when you take the address of a
nested function).</p>
<p>Fortran support generally works, but there are still several unresolved bugs
in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
tools/gfortran component for details. Note that llvm-gcc is missing major
Fortran performance work in the frontend and library that went into GCC after
4.2. If you are interested in Fortran, we recommend that you consider using
<a href="#dragonegg">dragonegg</a> instead.</p>
<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
actively maintained. If you are interested in Ada, we recommend that you
consider using <a href="#dragonegg">dragonegg</a> instead.</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2>
<a name="additionalinfo">Additional Information</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>A wide variety of additional information is available on
the <a href="http://llvm.org/">LLVM web page</a>, in particular in
the <a href="http://llvm.org/docs/">documentation</a> section. The web page
also contains versions of the API documentation which is up-to-date with the
Subversion version of the source code. You can access versions of these
documents specific to this release by going into the "<tt>llvm/doc/</tt>"
directory in the LLVM tree.</p>
<p>If you have any questions or comments about LLVM, please feel free to contact
us via the <a href="http://llvm.org/docs/#maillist"> mailing lists</a>.</p>
</div>
<!-- *********************************************************************** -->
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