Commit 2.7 release notes.
Update getting started guide for 2.7
git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_27@102412 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/GettingStarted.html b/docs/GettingStarted.html
index 8bb1ac4..05169f8 100644
--- a/docs/GettingStarted.html
+++ b/docs/GettingStarted.html
@@ -726,6 +726,7 @@
subdirectories of the '<tt>tags</tt>' directory:</p>
<ul>
+<li>Release 2.7: <b>RELEASE_27</b></li>
<li>Release 2.6: <b>RELEASE_26</b></li>
<li>Release 2.5: <b>RELEASE_25</b></li>
<li>Release 2.4: <b>RELEASE_24</b></li>
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html
index 3c350c7..19b92f1 100644
--- a/docs/ReleaseNotes.html
+++ b/docs/ReleaseNotes.html
@@ -10,6 +10,9 @@
<div class="doc_title">LLVM 2.7 Release Notes</div>
+<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>
@@ -25,11 +28,12 @@
<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 2.7
+<!--
+<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
release.<br>
You may prefer the
-<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6
-Release Notes</a>.</h1>
+<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.7
+Release Notes</a>.</h1>-->
<!-- *********************************************************************** -->
<div class="doc_section">
@@ -48,8 +52,8 @@
<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>
+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
@@ -64,22 +68,17 @@
include/llvm/Analysis/LiveValues.h => Dan
lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
- ABCD, SCCVN, GEPSplitterPass
+ ABCD, GEPSplitterPass
MSIL backend?
+ lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
-->
<!-- Features that need text if they're finished for 2.7:
- gcc plugin.
+ combiner-aa?
strong phi elim
- variable debug info for optimized code
- postalloc scheduler: anti dependence breaking, hazard recognizer?
- metadata
+ llvm.dbg.value: variable debug info for optimized code
loop dependence analysis
- ELF Writer? How stable?
- <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
- 2.7 supports the GDB 7.0 jit interfaces for debug info.
- 2.7 eliminates ADT/iterator.h
-->
<!-- for announcement email:
@@ -88,8 +87,7 @@
compiler_rt
KLEE web page at klee.llvm.org
Many new papers added to /pubs/
- Mention gcc plugin.
-
+ Mention gcc plugin.
-->
<!-- *********************************************************************** -->
@@ -117,12 +115,49 @@
<div class="doc_text">
-<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
+<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 and Objective-C on x86 (32- and 64-bit).</p>
<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
<ul>
-<li>...</li>
+
+<li>C++ Support: Clang is now capable of self-hosting! While still
+alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang,
+and C++ is now enabled by default. See the <a
+href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility
+page</a> for common C++ migration issues.</li>
+
+<li>Objective-C: Clang now includes experimental support for an updated
+Objective-C ABI on non-Darwin platforms. This includes support for non-fragile
+instance variables and accelerated proxies, as well as greater potential for
+future optimisations. The new ABI is used when compiling with the
+-fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these
+options may be mixed with code compiled with GCC or clang using the old GNU ABI,
+but requires the libobjc2 runtime from the GNUstep project.</li>
+
+<li>New warnings: Clang contains a number of new warnings, including
+control-flow warnings (unreachable code, missing return statements in a
+non-<code>void</code> function, etc.), sign-comparison warnings, and improved
+format-string warnings.</li>
+
+<li>CIndex API and Python bindings: Clang now includes a C API as part of the
+CIndex library. Although we may make some changes to the API in the future, it
+is intended to be stable and has been designed for use by external projects. See
+the Clang
+doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
+documentation for more details. The CIndex API also includes a preliminary
+set of Python bindings.</li>
+
+<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
+ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
+suitable for use as a beta quality ARM compiler.</li>
+
</ul>
</div>
@@ -133,13 +168,18 @@
<div class="doc_text">
-<p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also
-includes an early stage static source code analysis tool for <a
-href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
-in C and Objective-C programs. The tool performs checks to find
-bugs that occur on a specific path within a program.</p>
+<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
+ project is an effort to use static source code analysis techniques to
+ automatically find bugs in C and Objective-C programs (and hopefully <a
+ href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
+ future</a>!). The tool is very good at finding bugs that occur on specific
+ paths through code, such as on error conditions.</p>
-<p>In the LLVM 2.7 time-frame, the analyzer core has ...</p>
+<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
+ minor improvements, including better support for tracking the fields of
+ structures, initial support (not enabled by default yet) for doing
+ interprocedural (cross-function) analysis, and new checks have been added.
+</p>
</div>
@@ -156,13 +196,23 @@
compilation.</p>
<p>
-VMKit version ?? builds with LLVM 2.7 and you can find it on its
-<a href="http://vmkit.llvm.org/releases/">web page</a>. The release includes
-bug fixes, cleanup and new features. The major changes are:</p>
+With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
+virtual machines. VMKit now offers precise and efficient garbage collection with
+multi-threading support, thanks to the MMTk memory management toolkit, as well
+as just in time and ahead of time compilation with LLVM. The major changes in
+VMKit 0.27 are:</p>
<ul>
-<li>...</li>
+<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
+ The first collector to be ported is the MarkSweep collector, which is precise,
+ and drastically improves the performance of VMKit.</li>
+<li>Line number information in the JVM: by using the debug metadata of LLVM, the
+ JVM now supports precise line number information, useful when printing a stack
+ trace.</li>
+<li>Interface calls in the JVM: we implemented a variant of the Interface Method
+ Table technique for interface calls in the JVM.
+</li>
</ul>
</div>
@@ -186,39 +236,41 @@
<p>
All of the code in the compiler-rt project is available under the standard LLVM
-License, a "BSD-style" license.</p>
+License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
+supports ARM targets.</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="klee">KLEE: Symbolic Execution and Automatic Test Case Generator</a>
+<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
</div>
<div class="doc_text">
<p>
-The new LLVM <a href="http://klee.llvm.org/">KLEE project</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 algorithms. For more
-details, please see the <a
-href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
-KLEE.</p>
+<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
+gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
+gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
+whatsoever (currently one small patch is needed). This is thanks to the new
+<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
+makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
+which is nothing more than a dynamic library which conforms to the gcc plugin
+interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
+instead of the gcc optimizers, and the LLVM code generators instead of the gcc
+code generators, just like llvm-gcc. To use it, you add
+"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
+becomes llvm-gcc-4.5!
+</p>
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="dragonegg">DragonEgg: GCC-4.5 as an LLVM frontend</a>
-</div>
-
-<div class="doc_text">
<p>
-The goal of <a href="http://dragonegg.llvm.org/">DragonEgg</a> is to make
-gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever.
-<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a shared library (dragonegg.so)
-that is loaded by gcc at runtime. It ...
+DragonEgg is still a work in progress. Currently C works very well, while C++,
+Ada and Fortran work fairly well. All other languages either don't work at all,
+or only work poorly. For the moment only the x86-32 and x86-64 targets are
+supported, and only on linux and darwin (darwin needs an additional gcc patch).
+</p>
+
+<p>
+DragonEgg is a new project which is seeing its first release with llvm-2.7.
</p>
</div>
@@ -231,9 +283,27 @@
<div class="doc_text">
<p>
-The LLVM Machine Code (MC) Toolkit project is ...
+The LLVM Machine Code (aka MC) sub-project of LLVM 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. It is a sub-project of LLVM which provides it with a number of advantages
+over other compilers that do not have tightly integrated assembly-level tools.
+For a gentle introduction, 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>
+<p>2.7 includes major parts of the work required by the new MC Project. A few
+ targets have been refactored to support it, and work is underway to support a
+ native assembler in LLVM. This work is not complete in LLVM 2.7, but it has
+ made substantially more progress on LLVM mainline.</p>
+
+<p>One minor example of what MC can do is to transcode an AT&T syntax
+ X86 .s file into intel syntax. You can do this with something like:</p>
+<pre>
+ llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
+</pre>
+
</div>
@@ -250,48 +320,6 @@
projects that have already been updated to work with LLVM 2.7.</p>
</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="Rubinius">Rubinius</a>
-</div>
-
-<div class="doc_text">
-<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 core class
-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 uncommon traps are all used to
-remove dynamism from ruby execution and increase performance.</p>
-
-<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
-a counter based JIT, type feedback and speculative method inlining.
-</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="macruby">MacRuby</a>
-</div>
-
-<div class="doc_text">
-
-<p>
-<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
-core Mac OS X technologies, such as the Objective-C common runtime and garbage
-collector and the CoreFoundation framework. It is principally developed by
-Apple and aims at enabling the creation of full-fledged Mac OS X applications.
-</p>
-
-<p>
-MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
-expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
-handling.</p>
-
-</div>
-
-
<!--=========================================================================-->
<div class="doc_subsection">
<a name="pure">Pure</a>
@@ -308,28 +336,9 @@
an easy-to-use C interface. The interpreter uses LLVM as a backend to
JIT-compile Pure programs to fast native code.</p>
-<p>Pure versions ??? and later have been tested and are known to work with
-LLVM 2.7 (and continue to work with older LLVM releases >= 2.3 as well).
-</p>
-</div>
+<p>Pure versions 0.43 and later have been tested and are known to work with
+LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="ldc">LLVM D Compiler</a>
-</div>
-
-<div class="doc_text">
-<p>
-<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
-the D Programming Language using the LLVM optimizer and code generator.
-The LDC project works great with the LLVM 2.6 release. General improvements in
-this
-cycle have included new inline asm constraint handling, better debug info
-support, general bug fixes and better x86-64 support. This has allowed
-some major improvements in LDC, getting it much closer to being as
-fully featured as the original DMD compiler from DigitalMars.
-</p>
</div>
<!--=========================================================================-->
@@ -342,7 +351,8 @@
<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
source implementation of the PHP programming
language that uses LLVM for its optimizer, JIT and static compiler. This is a
-reimplementation of an earlier project that is now based on LLVM.</p>
+reimplementation of an earlier project that is now based on LLVM.
+</p>
</div>
<!--=========================================================================-->
@@ -355,20 +365,45 @@
<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
branch of <a href="http://python.org/">Python</a> intended to be fully
compatible and significantly faster. It uses LLVM's optimization passes and JIT
-compiler.</p>
+compiler.
+</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="llvm-lua">llvm-lua</a>
+<a name="tce">TTA-based Codesign Environment (TCE)</a>
</div>
<div class="doc_text">
<p>
-<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
-and static compiling support to the Lua VM. Lua bytecode is analyzed to
-remove type checks, then LLVM is used to compile the bytecode down to machine
-code.</p>
+<a href="http://tce.cs.tut.fi/">TCE</a> 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 llvm-gcc/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>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="safecode">SAFECode Compiler</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
+compiler built using LLVM. It takes standard, unannotated C code, analyzes the
+code to ensure that memory accesses and array indexing operations are safe, and
+instruments the code with run-time checks when safety cannot be proven
+statically.
+</p>
</div>
<!--=========================================================================-->
@@ -386,8 +421,62 @@
to provide native code generation without introducing processor-dependent
code.
</p>
+<p>Icedtea6 1.8 and later have been tested and are known to work with
+LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
+</p>
</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="llvm-lua">LLVM-Lua</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
+ to add JIT and static compiling support to the Lua VM. Lua
+bytecode is analyzed to remove type checks, then LLVM is used to compile the
+bytecode down to machine code.
+</p>
+<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
+</p>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="MacRuby">MacRuby</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on
+core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for
+optimization passes, JIT compilation and exception handling. It also allows
+static (ahead-of-time) compilation of Ruby code straight to machine code.
+</p>
+<p>The upcoming MacRuby 0.6 release works with LLVM 2.7.
+</p>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://www.haskell.org/ghc/">GHC</a> 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 now
+supports an <a
+href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
+code generator</a>. GHC supports LLVM 2.7.</p>
+
+</div>
<!-- *********************************************************************** -->
@@ -407,6 +496,39 @@
<!--=========================================================================-->
<div class="doc_subsection">
+<a name="orgchanges">LLVM Community Changes</a>
+</div>
+
+<div class="doc_text">
+
+<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
+organization changes have happened:
+</p>
+
+<ul>
+<li>LLVM has a new <a href="http://llvm.org/Logo.html">official logo</a>!</li>
+
+<li>Ted Kremenek and Doug Gregor have stepped forward as <a
+ href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
+ Clang static analyzer and the Clang frontend, respectively.</li>
+
+<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
+ <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
+ to learn about new LLVM-related features as they are implemented. Several
+ features in this release are already explained on the blog.</li>
+
+<li>The LLVM web pages are now checked into the SVN server, in the "www",
+ "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
+ largely inaccessible old CVS server.</li>
+
+<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
+ faster) server. It is still graciously hosted at the University of Illinois
+ of Urbana Champaign.</li>
+</ul>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
<a name="majorfeatures">Major New Features</a>
</div>
@@ -415,7 +537,40 @@
<p>LLVM 2.7 includes several major new capabilities:</p>
<ul>
-<li>...</li>
+<li>2.7 includes initial support for the <a
+ href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
+ MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
+
+<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
+ supports many different use cases, including allowing front-end authors to
+ encode source level information into LLVM IR, which is consumed by later
+ language-specific passes. This is a great way to do high-level optimizations
+ like devirtualization, type-based alias analysis, etc. See the <a
+ href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
+ Extensible Metadata Blog Post</a> for more information.</li>
+
+<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
+in a completely new way, built on extensible metadata. The new implementation
+is much more memory efficient and paves the way for improvements to optimized
+code debugging experience.</li>
+
+<li>2.7 now directly supports taking the address of a label and doing an
+ indirect branch through a pointer. This is particularly useful for
+ interpreter loops, and is used to implement the GCC "address of label"
+ extension. For more information, see the <a
+href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
+Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
+
+<li>2.7 is the first release to start supporting APIs for assembling and
+ disassembling target machine code. These APIs are useful for a variety of
+ low level clients, and are surfaced in the new "enhanced disassembly" API.
+ For more information see the <a
+ href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
+ Disassembler Blog Post</a> for more information.</li>
+
+<li>2.7 includes major parts of the work required by the new MC Project,
+ see the <a href="#mc">MC update above</a> for more information.</li>
+
</ul>
</div>
@@ -430,7 +585,30 @@
expose new optimization opportunities:</p>
<ul>
-<li>...</li>
+<li>LLVM IR now supports a 16-bit "half float" data type through <a
+ href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
+<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
+ attributes</a>: inlinehint and alignstack(n). The former is a hint to the
+ optimizer that a function was declared 'inline' and thus the inliner should
+ weight it higher when considering inlining it. The later
+ indicates to the code generator that the function diverges from the platform
+ ABI on stack alignment.</li>
+<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
+ allows the optimizer to infer the sizes of memory objects in some cases.
+ This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
+ extension.</li>
+<li>LLVM IR now supports marking load and store instructions with <a
+ href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
+ metadata feature). This hint encourages the code
+ generator to generate non-temporal accesses when possible, which are useful
+ for code that is carefully managing cache behavior. Currently, only the
+ X86 backend provides target support for this feature.</li>
+
+<li>LLVM 2.7 has pre-alpha support for <a
+ href="LangRef.html#t_union">unions in LLVM IR</a>.
+ Unfortunately, this support is not really usable in 2.7, so if you're
+ interested in pushing it forward, please help contribute to LLVM mainline.</li>
+
</ul>
</div>
@@ -447,12 +625,51 @@
<ul>
-<li>...</li>
+<li>The inliner reuses now merges arrays stack objects in different callees when
+ inlining multiple call sites into one function. This reduces the stack size
+ of the resultant function.</li>
+<li>The -basicaa alias analysis pass (which is the default) has been improved to
+ be less dependent on "type safe" pointers. It can now look through bitcasts
+ and other constructs more aggressively, allowing better load/store
+ optimization.</li>
+<li>The load elimination optimization in the GVN Pass [<a
+href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
+ blog post</a>] has been substantially improved to be more aggressive about
+ partial redundancy elimination and do more aggressive phi translation. Please
+ see the <a
+ href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
+ Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
+ Blog Post</a> for more details.</li>
+<li>The module <a href="LangRef.html#datalayout">target data string</a> now
+ includes a notion of 'native' integer data types for the target. This
+ helps mid-level optimizations avoid promoting complex sequences of
+ operations to data types that are not natively supported (e.g. converting
+ i32 operations to i64 on 32-bit chips).</li>
+<li>The mid-level optimizer is now conservative when operating on a module with
+ no target data. Previously, it would default to SparcV9 settings, which is
+ not what most people expected.</li>
+<li>Jump threading is now much more aggressive at simplifying correlated
+ conditionals and threading blocks with otherwise complex logic. It has
+ subsumed the old "Conditional Propagation" pass, and -condprop has been
+ removed from LLVM 2.7.</li>
+<li>The -instcombine pass has been refactored from being one huge file to being
+ a library of its own. Internally, it uses a customized IRBuilder to clean
+ it up and simplify it.</li>
+
+<li>The optimal edge profiling pass is reliable and much more complete than in
+ 2.6. It can be used with the llvm-prof tool but isn't wired up to the
+ llvm-gcc and clang command line options yet.</li>
+
+<li>A new experimental alias analysis implementation, -scev-aa, has been added.
+ It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
+ pointer offset expressions to disambiguate pointers. It can catch a few
+ cases that basicaa cannot, particularly in complex loop nests.</li>
+
+<li>The default pass ordering has been tweaked for improved optimization
+ effectiveness.</li>
</ul>
-<p>Also, -anders-aa was removed</p>
-
</div>
@@ -464,15 +681,20 @@
<div class="doc_text">
<ul>
-<li>The JIT now <a
-href="http://llvm.org/viewvc/llvm-project?view=rev&revision=85295">defaults
+<li>The JIT now supports generating debug information and is compatible with
+the new GDB 7.0 (and later) interfaces for registering dynamically generated
+debug info.</li>
+
+<li>The JIT now <a href="http://llvm.org/PR5184">defaults
to compiling eagerly</a> to avoid a race condition in the lazy JIT.
Clients that still want the lazy JIT can switch it on by calling
<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
+
<li>It is now possible to create more than one JIT instance in the same process.
These JITs can generate machine code in parallel,
although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
still have to obey the other threading restrictions</a>.</li>
+
</ul>
</div>
@@ -489,8 +711,49 @@
it run faster:</p>
<ul>
+<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
+ to emit many useful comments to .s files indicating information about spill
+ slots and loop nest structure. This should make it much easier to read and
+ understand assembly files. This is wired up in llvm-gcc and clang to
+ the <tt>-fverbose-asm</tt> option.</li>
-<li>...</li>
+<li>New LSR with "full strength reduction" mode, which can reduce address
+ register pressure in loops where address generation is important.</li>
+
+<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
+ is available and enabled by default. It catches redundancies exposed by
+ lowering.</li>
+<li>A new pre-register-allocation tail duplication pass is available and enabled
+ by default, it can substantially improve branch prediction quality in some
+ cases.</li>
+<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
+ is available and enabled by default. This pass can takes advantage
+ architecture features like x86-64 implicit zero extension behavior and
+ sub-registers.</li>
+<li>The code generator now supports a mode where it attempts to preserve the
+ order of instructions in the input code. This is important for source that
+ is hand scheduled and extremely sensitive to scheduling. It is compatible
+ with the GCC <tt>-fno-schedule-insns</tt> option.</li>
+<li>The target-independent code generator now supports generating code with
+ arbitrary numbers of result values. Returning more values than was
+ previously supported is handled by returning through a hidden pointer. In
+ 2.7, only the X86 and XCore targets have adopted support for this
+ though.</li>
+<li>The code generator now supports generating code that follows the
+ <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
+ Convention</a> and ABI.</li>
+<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
+ selection</a>" phase of the code generator has been largely rewritten for
+ 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
+ linked into the target to do the pattern matching, now it emits a much
+ smaller table which is read by the target-independent code. The primary
+ advantages of this approach is that the size and compile time of various
+ targets is much improved. The X86 code generator shrunk by 1.5MB of code,
+ for example.</li>
+<li>Almost the entire code generator has switched to emitting code through the
+ MC interfaces instead of printing textually to the .s file. This led to a
+ number of cleanups and speedups. In 2.7, debug an exception handling
+ information does not go through MC yet.</li>
</ul>
</div>
@@ -504,31 +767,12 @@
</p>
<ul>
+<li>The X86 backend now optimizes tails calls much more aggressively for
+ functions that use the standard C calling convention.</li>
+<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
+ registers, making the code generator more aggressive in cases where scalars
+ and vector types are mixed.</li>
-<li>...</li>
-
-</ul>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="pic16">PIC16 Target Improvements</a>
-</div>
-
-<div class="doc_text">
-<p>New features of the PIC16 target include:
-</p>
-
-<ul>
-<li>...</li>
-</ul>
-
-<p>Things not yet supported:</p>
-
-<ul>
-<li>Variable arguments.</li>
-<li>Interrupts/programs.</li>
</ul>
</div>
@@ -544,7 +788,28 @@
<ul>
-<li>...</li>
+<li>The ARM backend now generates instructions in unified assembly syntax.</li>
+
+<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
+ support differs slightly from the GCC implementation. Please see the
+ <a
+href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
+ ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
+ helpful information if migrating code from GCC to LLVM-GCC.</li>
+
+<li>The ARM and Thumb code generators now use register scavenging for stack
+ object address materialization. This allows the use of R3 as a general
+ purpose register in Thumb1 code, as it was previous reserved for use in
+ stack address materialization. Secondly, sequential uses of the same
+ value will now re-use the materialized constant.</li>
+
+<li>The ARM backend now has good support for ARMv4 targets and has been tested
+ on StrongARM hardware. Previously, LLVM only supported ARMv4T and
+ newer chips.</li>
+
+<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize,
+ __sync_fetch_and_add, etc.).</li>
+
</ul>
@@ -552,21 +817,6 @@
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="OtherTarget">Other Target Specific Improvements</a>
-</div>
-
-<div class="doc_text">
-<p>New features of other targets include:
-</p>
-
-<ul>
-<li>...</li>
-</ul>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
<a name="newapis">New Useful APIs</a>
</div>
@@ -577,7 +827,34 @@
</p>
<ul>
-<li>...</li>
+<li>The optimizer uses the new CodeMetrics class to measure the size of code.
+ Various passes (like the inliner, loop unswitcher, etc) all use this to make
+ more accurate estimates of the code size impact of various
+ optimizations.</li>
+<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
+ llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
+ symbolic simplification of instructions (e.g. <tt>a+0</tt> -> <tt>a</tt>)
+ without requiring the instruction to exist. This centralizes a lot of
+ ad-hoc symbolic manipulation code scattered in various passes.</li>
+<li>The optimizer now uses a new <a
+ href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
+ class which efficiently supports
+ doing unstructured SSA update operations. This centralized a bunch of code
+ scattered throughout various passes (e.g. jump threading, lcssa,
+ loop rotate, etc) for doing this sort of thing. The code generator has a
+ similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
+ MachineSSAUpdater</a> class.</li>
+<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
+ llvm/Support/Regex.h</a> header exposes a platform independent regular
+ expression API. Building on this, the <a
+ href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
+ regular exressions.</li>
+<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
+ By default, this stream works the same way as "errs()", but if you pass
+ <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
+ fixed sized circular buffer and the output is printed at the end of the
+ program's execution. This is helpful if you have a long lived compiler
+ process and you're interested in seeing snapshots in time.</li>
</ul>
@@ -592,7 +869,16 @@
<p>Other miscellaneous features include:</p>
<ul>
-<li>...</li>
+<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
+ get this, configure LLVM with the --enable-shared option.</li>
+
+<li>LLVM command line tools now overwrite their output by default. Previously,
+ they would only do this with -f. This makes them more convenient to use, and
+ behave more like standard unix tools.</li>
+
+<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
+ file, and automatically do the right thing. This means you don't need to
+ explicitly use the llvm-as tool for most things.</li>
</ul>
</div>
@@ -610,20 +896,48 @@
from the previous release.</p>
<ul>
+
+<li>
+The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
+("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
+profiling ("rsprofiling") passes have all been removed. They were not being
+actively maintained and had substantial problems. If you are interested in
+these components, you are welcome to ressurect them from SVN, fix the
+correctness problems, and resubmit them to mainline.</li>
+
+<li>LLVM now defaults to building most libraries with RTTI turned off, providing
+a code size reduction. Packagers who are interested in building LLVM to support
+plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
+and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
+document.</li>
+
<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
if you have it installed. This makes it more likely that an LLVM built on one
system will work when copied to a similar system. To use <tt>libffi</tt>,
-configure with <tt>--enable-libffi</tt>.
-</li>
-</ul>
+configure with <tt>--enable-libffi</tt>.</li>
+<li>Debug information uses a completely different representation, an LLVM 2.6
+.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
+
+<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
+ along with LowerAllocations pass. Now you should just use a call to the
+ malloc and free functions in libc. These calls are optimized as well as
+ the old instructions were.</li>
+</ul>
<p>In addition, many APIs have changed in this release. Some of the major LLVM
API changes are:</p>
<ul>
+<li>Just about everything has been converted to use <tt>raw_ostream</tt> instead of
+ <tt>std::ostream</tt>.</li>
+<li><tt>llvm/ADT/iterator.h</tt> has been removed, just use <tt><iterator></tt>
+ instead.</li>
+<li>The <tt>Streams.h</tt> file and <tt>DOUT</tt> got removed, use <tt>DEBUG(errs() << ...);</tt>
+ instead.</li>
+<li>The <tt>TargetAsmInfo</tt> interface was renamed to <tt>MCAsmInfo</tt>.</li>
<li><tt>ModuleProvider</tt> has been <a
-href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
+href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
replace <tt>getBitcodeModuleProvider</tt> with
@@ -641,15 +955,24 @@
<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
<tt>GlobalValue::isMaterializable</tt>.</li>
-<li>FIXME: Debug info has been totally redone. Add pointers to new APIs. Substantial caveats about compatibility of .ll and .bc files.</li>
-
-<li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
-to <tt>llvm/System/DataTypes.h</tt>.</li>
-
<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
+
+<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
+<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
+ booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
+<li>Some header files have been renamed:
+<ul>
+ <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
+ <tt>llvm/System/AIXDataTypesFix.h</tt></li>
+ <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
+ <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
+ <tt>llvm/Analysis/InlineCost.h</tt></li>
+ <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
+ <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
+</ul></li>
</ul>
</div>
@@ -670,7 +993,7 @@
<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
systems).</li>
-<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
+<li>PowerPC and X86-based Mac OS X systems, running 10.4 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
@@ -699,13 +1022,7 @@
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</p>
-<ul>
-<li>The llvm-gcc bootstrap will fail with some versions of binutils (e.g. 2.15)
- with a message of "<tt><a href="http://llvm.org/PR5004">Error: can not do 8
- byte pc-relative relocation</a></tt>" when building C++ code. We intend to
- fix this on mainline, but a workaround is to upgrade to binutils 2.17 or
- later.</li>
-
+<ul>
<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
using the stock GCC 3.x.x series 'out the box',
See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
@@ -731,10 +1048,11 @@
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430 and SystemZ backends are
- experimental.</li>
-<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
- supported value for this option. The ELF writer is experimental.</li>
+<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
+ backends are experimental.</li>
+<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
+ supported value for this option. The MachO writer is experimental, and
+ works much better in mainline SVN.</li>
</ul>
</div>
@@ -755,13 +1073,10 @@
to generate code for systems that don't have SSE2.</li>
<li>Win64 code generation wasn't widely tested. Everything should work, but we
expect small issues to happen. Also, llvm-gcc cannot build the mingw64
- runtime currently due
- to <a href="http://llvm.org/PR2255">several</a>
- <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
- the
- 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
+ runtime currently due to lack of support for the 'u' inline assembly
+ constraint and for X87 floating point inline assembly.</li>
<li>The X86-64 backend does not yet support the LLVM IR instruction
- <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
+ <tt>va_arg</tt>. Currently, front-ends support variadic
argument constructs on X86-64 by lowering them manually.</li>
</ul>
@@ -789,9 +1104,6 @@
<div class="doc_text">
<ul>
-<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
-and not well tested. Some features may not work at all, and the code quality
-may be poor in some cases.</li>
<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>
@@ -865,7 +1177,7 @@
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
+ <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
</div>
<div class="doc_text">
@@ -876,27 +1188,6 @@
supported on some targets (these are used when you take the address of a
nested function).</p>
-<p>If you run into GCC extensions which are not supported, please let us know.
-</p>
-
-</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
-</div>
-
-<div class="doc_text">
-
-<p>The C++ front-end is considered to be fully
-tested and works for a number of non-trivial programs, including LLVM
-itself, Qt, Mozilla, etc.</p>
-
-<ul>
-<li>Exception handling works well on the X86 and PowerPC targets. Currently
- only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
-</ul>
-
</div>
<!-- ======================================================================= -->
@@ -951,20 +1242,6 @@
</ul>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ocaml-bindings">Known problems with the O'Caml bindings</a>
-</div>
-
-<div class="doc_text">
-
-<p>The <tt>Llvm.Linkage</tt> module is broken, and has incorrect values. Only
-<tt>Llvm.Linkage.External</tt>, <tt>Llvm.Linkage.Available_externally</tt>, and
-<tt>Llvm.Linkage.Link_once</tt> will be correct. If you need any of the other linkage
-modes, you'll have to write an external C library in order to expose the
-functionality. This has been fixed in the trunk.</p>
-</div>
-
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="additionalinfo">Additional Information</a>
