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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 2.1 Release Notes</title>
</head>
<body>
<div class="doc_title">LLVM 2.1 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#whatsnew">What's New?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#portability">Portability and Supported Platforms</a></li>
<li><a href="#knownproblems">Known Problems</a>
<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>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="intro">Introduction</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This document contains the release notes for the LLVM compiler
infrastructure, release 2.1. Here we describe the status of LLVM, including
major improvements from the previous release and any 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://mail.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 releases, please see the
<a href="http://llvm.org/releases/">releases page</a>.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="whatsnew">What's New?</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This is the twelfth public release of the LLVM Compiler Infrastructure.
It includes many features and refinements from LLVM 2.0.</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="frontends">New Frontends</a>
</div>
<div class="doc_text">
<p>LLVM 2.1 brings two new beta C front-ends. First, Duncan, Anton and Devang
has started syncing up llvm-gcc with GCC 4.2, yielding "llvm-gcc 4.2" (creative,
huh?). llvm-gcc 4.2 has the promise to bring much better FORTRAN and Ada
support to LLVM as well as features like atomic builtins, OpenMP, and many other
things. Check it out!</p>
<p>Second, LLVM now includes its own native C and Objective-C front-end (C++ is
in progress, but is not very far along) code named "<a
href="http://clang.llvm.org/">clang</a>". This front-end has a number of great
features, primarily aimed at source-level analysis and speeding up compile-time.
At this point though, the LLVM Code Generator component is still very early in
development, so it's mostly useful for people looking to build source-level
analysis tools or source-to-source translators.</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="optimizer">Optimizer Improvements</a>
</div>
<div class="doc_text">
<p>Some of the most noticable improvements this release have been in the
optimizer, speeding it up and making it more aggressive</p>
<ul>
<li>Owen DSE and MemDep analysis</li>
<li>Owen GVN</li>
<li>Owen GVN-PRE, not in llvm-gcc</li>
<li>Devang merged ETForest and DomTree into a single easier to use data
structure.</li>
<li>Nick Lewycky improved loop trip count analysis to handle many more common
cases.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="codegen">Code Generator Improvements</a>
</div>
<div class="doc_text">
<ul>
<li>Dale finished up the Tail Merging optimization in the code generator,
enabling it by default. This produces smaller code that is also faster in some
cases.</li>
<li>Dan Gohman changed the way we represent vectors before legalization,
significantly simplifying the SelectionDAG representation for these and making
the code generator faster for vector code.</li>
<li>Evan remat rewrite (coalesced intervals + folding of remat'd loads) and
live intervals improvements.</li>
<li>Dan Gohman contributed support for better alignment and volatility handling
in the code generator, and significantly enhanced alignment analysis for SSE
load/store instructions.</li>
<li>Christopher Lamb virtual register sub-register support, better truncates and
extends on X86.</li>
<li>Duraid Madina contributed a new "bigblock" register allocator, and Roman
Levenstein contributed several big improvements. BigBlock is optimized for code
that uses very large basic blocks. It is slightly slower than the "local"
allocator, but produces much better code.</li>
<li>David Greene refactored the register allocator to split coalescing out from
allocation, making coalescers pluggable.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="targetspecific">Target Specific Improvements</a>
</div>
<div class="doc_text">
<p>New features include:
</p>
<ul>
<li>Bruno Cardoso Lopes contributed initial MIPS support.</li>
<li>Bill Wendling added SSSE3 support.</li>
<li>New Target independent if converter, ARM uses it so far</li>
<li>Nicholas Geoffray contributed improved linux/ppc ABI and JIT support.</li>
<li>Dale Johannesen rewrote handling of 32-bit float values in the X86 backend
when using the floating point stack, fixing several nasty bugs.</li>
<li>Dan contributed rematerialization support for the X86 backend.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="llvmgccimprovements">llvm-gcc Improvements</a>
</div>
<div class="doc_text">
<p>New features include:
</p>
<ul>
<li>Duncan and Anton exception handling in llvm-gcc 4.0/4.2</li>
<li>Devang and Duncan: Bitfields, pragma pack</li>
<li>Tanya implemented support for __attribute__((noinline)) in llvm-gcc, and
added support for generic variable annotations which are propagated into the
LLVM IR, e.g. "<tt>int X __attribute__((annotate("myproperty")));</tt>".</li>
<li>Sheng Zhou and Christopher Lamb implemented alias analysis support for
'restrict' arguments to functions.</li>
<li>Duncan contributed support for trampolines (pointers to nested functions),
currently only supported on x86 target.</li>
<li> Lauro Ramos Venancio contributed support to encode alignment info in
load and store instructions.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="coreimprovements">LLVM Core Improvements</a>
</div>
<div class="doc_text">
<p>New features include:
</p>
<ul>
<li>Neil Booth APFloat, foundation for long double support that will be wrapped
up in 2.2. Dale contributed most of long double support, will be enabled in
2.2.</li>
<li>LLVM now provides an LLVMBuilder class which makes it significantly easier
to create LLVM IR instructions.</li>
<li>Reid contributed support for intrinsics that take arbitrary integer typed
arguments, Dan Gohman and Chandler extended it to support FP and vectors.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="otherimprovements">Other Improvements</a>
</div>
<div class="doc_text">
<p>New features include:
</p>
<ul>
<li>BrainF frontend by Sterling Stein.</li>
<li>David Green contributed a new --enable-expensive-checks configure option
which enables STL checking, and fixed several bugs exposed by it.</li>
</ul>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="portability">Portability and Supported Platforms</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>LLVM is known to work on the following platforms:</p>
<ul>
<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
(and probably other unix-like systems).</li>
<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
64-bit modes.</li>
<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
support is available for native builds with Visual C++).</li>
<li>Sun UltraSPARC workstations running Solaris 8.</li>
<li>Alpha-based machines running Debian GNU/Linux.</li>
<li>Itanium-based machines running Linux and HP-UX.</li>
</ul>
<p>The core LLVM infrastructure uses
<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
to the machine and operating system on which it is built. However, minor
porting may be required to get LLVM to work on new platforms. We welcome your
portability patches and reports of successful builds or error messages.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="knownproblems">Known Problems</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This section contains all known problems with the LLVM system, listed by
component. As new problems are discovered, they will be added to these
sections. 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>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="experimental">Experimental features included with this release</a>
</div>
<div class="doc_text">
<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 <
|
