<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.5 Release Notes</title>
+ <title>LLVM 2.7 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.5 Release Notes</div>
+<div class="doc_title">LLVM 2.7 Release Notes</div>
+
+<img align=right src="http://llvm.org/img/DragonSmall.png"
+ width="136" height="136">
<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 2.5</a></li>
- <li><a href="#whatsnew">What's New in LLVM 2.5?</a></li>
+ <li><a href="#externalproj">External Projects Using LLVM 2.7</a></li>
+ <li><a href="#whatsnew">What's New in LLVM 2.7?</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>
<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
+release.<br>
+You may prefer the
+<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6
+Release Notes</a>.</h1>
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="intro">Introduction</a>
<div class="doc_text">
<p>This document contains the release notes for the LLVM Compiler
-Infrastructure, release 2.5. Here we describe the status of LLVM, including
+Infrastructure, release 2.7. 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://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
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>
-<!-- Unfinished features in 2.5:
- Machine LICM
- Machine Sinking
- target-specific intrinsics
- gold lto plugin
- pre-alloc splitter, strong phi elim
- <tt>llc -enable-value-prop</tt>, propagation of value info
- (sign/zero ext info) from one MBB to another
- debug info for optimized code
- interpreter + libffi
- postalloc scheduler: anti dependence breaking, hazard recognizer?
+<p>FIXME: llvm.org moved to new server, mention new logo, Ted and Doug new code
+ owners.</p>
-initial support for debug line numbers when optimization enabled, not useful in
- 2.5 but will be for 2.6.
+</div>
+
+<!--
+Almost dead code.
+ 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
+ MSIL backend?
+ lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
+-->
+
+
+<!-- Features that need text if they're finished for 2.7:
+ gcc plugin.
+ strong phi elim
+ variable debug info for optimized code
+ postalloc scheduler: anti dependence breaking, hazard recognizer?
+ metadata
+ loop dependence analysis
+ ELF Writer? How stable?
+ <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
-->
<!-- for announcement email:
+ Logo web page.
+ llvm devmtg
+ compiler_rt
+ KLEE web page at klee.llvm.org
+ Many new papers added to /pubs/
+ Mention gcc plugin.
-->
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
-The LLVM 2.5 distribution currently consists of code from the core LLVM
-repository —which roughly includes the LLVM optimizers, code generators
-and supporting tools — and the llvm-gcc repository. In addition to this
-code, the LLVM Project includes other sub-projects that are in development. The
-two which are the most actively developed are the <a href="#clang">Clang
-Project</a> and the <a href="#vmkit">VMKit Project</a>.
+The LLVM 2.7 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>
</div>
<div class="doc_text">
-<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
-a set of new 'LLVM native' front-end technologies for the LLVM optimizer and
-code generator. While Clang is not included in the LLVM 2.5 release, it is
-continuing to make major strides forward in all areas. Its C and Objective-C
-parsing and code generation support is now very solid. For example, it is
-capable of successfully building many real-world applications for X86-32
-andX86-64,
-including <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">the FreeBSD
-kernel</a>. C++ is also
-making <a href="http://clang.llvm.org/cxx_status.html">incredible progress</a>,
-and work on templates has recently started.</p>
+<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
-<p>While Clang is not yet production quality, it is progressing very nicely and
-is quite usable for building many C and Objective-C applications. If you are
-interested in fast compiles and good diagnostics, we encourage you to try it out
-by <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
-and reporting any issues you hit to the <a
-href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
-list</a>.</p>
-
-<p>In the LLVM 2.5 time-frame, the Clang team has made many improvements:</p>
+<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
<ul>
-<li>Clang now has a new driver, which is focused on providing a GCC-compatible
- interface.</li>
-<li>The X86-64 ABI is now supported.</li>
-<li>Precompiled header support is now implemented.</li>
-<li>Objective-C support is significantly improved beyond LLVM 2.4, supporting
- many features, such as Objective-C Garbage Collection.</li>
-<li>Many many bugs are fixed and many features have been added.</li>
+<li>...</li>
+include a link to cxx_compatibility.html
</ul>
</div>
<div class="doc_text">
-<p>Previously announced in the last LLVM release, the Clang project also
+<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 a growing set of checks to find
+in C and Objective-C programs. The tool performs checks to find
bugs that occur on a specific path within a program.</p>
-<p>In the LLVM 2.5 time-frame there have been many significant improvements to
-the analyzer's core path simulation engine and machinery for generating
-path-based bug reports to end-users. Particularly noteworthy improvements
-include experimental support for full field-sensitivity and reasoning about heap
-objects as well as an improved value-constraints subengine that does a much
-better job of reasoning about inequality relationships (e.g., <tt>x > 2</tt>)
-between variables and constants.
-
-<p>The set of checks performed by the static analyzer continue to expand, and
-future plans for the tool include full source-level inter-procedural analysis
-and deeper checks such as buffer overrun detection. There are many opportunities
-to extend and enhance the static analyzer, and anyone interested in working on
-this project is encouraged to get involved!</p>
+<p>In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...</p>
</div>
<div class="doc_text">
<p>
The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
-a JVM and a CLI Virtual Machines (Microsoft .NET is an
-implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
+a JVM and a CLI Virtual Machine (Microsoft .NET is an
+implementation of the CLI) using LLVM for static and just-in-time
+compilation.</p>
-<p>Following LLVM 2.5, VMKit has its second release that you can find on its
-<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
+<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>
<ul>
-<li>Ahead of Time compiler: compiles .class files to llvm .bc. VMKit uses this
-functionality to native compile the standard classes (e.g. java.lang.String).
-Users can compile AoT .class files into dynamic libraries and run them with the
-help of VMKit.</li>
+<li>...</li>
+
+</ul>
+</div>
+
-<li>New exception model: the dwarf exception model is very slow for
-exception-intensive applications, so the JVM has had a new implementation of
-exceptions which check at each function call if an exception happened. There is
-a low performance penalty on applications without exceptions, but it is a big
-gain for exception-intensive applications. For example the jack benchmark in
-Spec JVM98 is 6x faster (performance gain of 83%).</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
+</div>
-<li>User-level management of thread stacks, so that thread local data access
-at runtime is fast and portable. </li>
+<div class="doc_text">
+<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>
-<li>Implementation of biased locking for faster object synchronizations at
-runtime.</li>
+<p>
+All of the code in the compiler-rt project is available under the standard LLVM
+License, a "BSD-style" license.</p>
-<li>New support for OSX/X64, Linux/X64 (with the Boehm GC) and Linux/ppc32.</li>
+</div>
-</ul>
+<!--=========================================================================-->
+<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 ...
+</p>
+
+</div>
+
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="mc">llvm-mc: Machine Code Toolkit</a>
</div>
+<div class="doc_text">
+<p>
+The LLVM Machine Code (MC) Toolkit project is ...
+</p>
+
+</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="externalproj">External Projects Using LLVM 2.5</a>
+ <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
</div>
<!-- *********************************************************************** -->
+<div class="doc_text">
+
+<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 2.7.</p>
+</div>
+
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="Rubinius">Rubinius</a>
+</div>
+
+<div class="doc_text">
+Need update.
+<!--
+<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>
+Need update.
+<!--
+<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>
an easy-to-use C interface. The interpreter uses LLVM as a backend to
JIT-compile Pure programs to fast native code.</p>
-<p>In addition to the usual algebraic data structures, Pure also has
-MATLAB-style matrices in order to support numeric computations and signal
-processing in an efficient way. Pure is mainly aimed at mathematical
-applications right now, but it has been designed as a general purpose language.
-The dynamic interpreter environment and the C interface make it possible to use
-it as a kind of functional scripting language for many application areas.
-</p>
+<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>
<div class="doc_text">
<p>
+Need update.
+<!--
<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.
-LDC project works great with the LLVM 2.5 release. General improvements in this
+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 bugfixes, and better x86-64 support. This has allowed
-some major improvements in LDC, getting us much closer to being as
-fully featured as the original DMD compiler from DigitalMars.
+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>
</div>
<div class="doc_text">
-<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
-source compiler for 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 the LLVM.</p>
+<p>
+<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>
</div>
-
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="whatsnew">What's New in LLVM 2.5?</a>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="UnladenSwallow">Unladen Swallow</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
-
-<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>
+<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>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="majorfeatures">Major New Features</a>
+<a name="llvm-lua">llvm-lua</a>
</div>
<div class="doc_text">
+<p>
+Need update.
+<!--
+<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>
+</div>
-<p>LLVM 2.5 includes several major new capabilities:</p>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
+</div>
-<ul>
-<li>LLVM 2.5 includes a brand new <a
-href="http://en.wikipedia.org/wiki/XCore">XCore</a> backend.</li>
+<div class="doc_text">
+<p>
+Need update.
+<!--
+<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>
+</div>
-<li>llvm-gcc now generally supports the GFortran front-end, and the precompiled
-release binaries now support Fortran, even on Mac OS/X.</li>
-<li>CMake is now used by the <a href="GettingStartedVS.html">LLVM build process
-on Windows</a>. It automatically generates Visual Studio project files (and
-more) from a set of simple text files. This makes it much easier to
-maintain. In time, we'd like to standardize on CMake for everything.</li>
-<li>LLVM 2.5 now uses (and includes) Google Test for unit testing.</li>
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="whatsnew">What's New in LLVM 2.7?</a>
+</div>
+<!-- *********************************************************************** -->
-<li>The LLVM native code generator now supports arbitrary precision integers.
-Types like <tt>i33</tt> have long been valid in the LLVM IR, but were previously
-only supported by the interpreter. Note that the C backend still does not
-support these.</li>
+<div class="doc_text">
-<li>LLVM 2.5 no longer uses 'bison', so it is easier to build on Windows.</li>
-</ul>
+<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>
</div>
-
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
+<a name="majorfeatures">Major New Features</a>
</div>
<div class="doc_text">
-<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
-front-ends and driver with the LLVM optimizer and code generator. It currently
-includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
+<p>LLVM 2.7 includes several major new capabilities:</p>
<ul>
-<li>In this release, the GCC inliner is completely disabled. Previously the GCC
-inliner was used to handle always-inline functions and other cases. This caused
-problems with code size growth, and it is completely disabled in this
-release.</li>
-
-<li>llvm-gcc (and LLVM in general) now support code generation for stack
-canaries, which is an effective form of <a
-href="http://en.wikipedia.org/wiki/Stack-smashing_protection">buffer overflow
-protection</a>. llvm-gcc supports this with the <tt>-fstack-protector</tt>
-command line option (just like GCC). In LLVM IR, you can request code
-generation for stack canaries with function attributes.
-</li>
+<li>...</li>
</ul>
-</div>
+Extensible metadata solid.
+
+Debug info improvements: using metadata instead of llvm.dbg global variables.
+This brings several enhancements including improved compile times.
+
+New instruction selector.
+GHC Haskell ABI/ calling conv support.
+Pre-Alpha support for unions in IR.
+New InlineHint and StackAlignment function attributes
+Code generator MC'ized except for debug info and EH.
+New SCEV AA pass: -scev-aa
+Inliner reuses arrays allocas when inlining multiple callers to reduce stack usage.
+MC encoding and disassembler apis.
+Optimal Edge Profiling?
+Instcombine is now a library, has its own IRBuilder to simplify itself.
+New llvm/Support/Regex.h API. FileCheck now does regex's
+Many subtle pointer invalidation bugs in Callgraph have been fixed and it now uses asserting value handles.
+MC Disassembler (with blog post), MCInstPrinter. Many X86 backend and AsmPrinter simplifications
+Various tools like llc and opt now read either .ll or .bc files as input.
+Malloc and free instructions got removed.
+compiler-rt support for ARM.
+completely llvm-gcc NEON support.
+Can transcode from GAS to intel syntax with "llvm-mc foo.s -output-asm-variant=1"
+JIT debug information with GDB 7.0
+New CodeGen Level CSE
+CMake can now run tests, what other improvements?
+ARM/Thumb using reg scavenging for stack object address materialization (PEI).
+New SSAUpdater and MachineSSAUpdater classes for unstructured ssa updating,
+ changed jump threading, GVN, etc to use it which simplified them and speed
+ them up.
+Combiner-AA improvements, why not on by default?
+Pre-regalloc tail duplication
+x86 sibcall optimization
+New LSR with full strength reduction mode
+The most awesome sext / zext optimization pass. ?
+
+
+
+CondProp pass removed (functionality merged into jump threading).
+AndersAA got removed (from 2.7 or mainline?)
+PredSimplify, LoopVR, GVNPRE got removed.
+LLVM command line tools now overwrite their output, before they would only do this with -f.
+DOUT removed, use DEBUG(errs() instead.
+Much stuff converted to use raw_ostream instead of std::ostream.
+TargetAsmInfo renamed to MCAsmInfo
+llvm/ADT/iterator.h gone.
+
+</div>
<!--=========================================================================-->
<div class="doc_subsection">
</div>
<div class="doc_text">
-<p>LLVM IR has several new features that are used by our existing front-ends and
-can be useful if you are writing a front-end for LLVM:</p>
+<p>LLVM IR has several new features for better support of new targets and that
+expose new optimization opportunities:</p>
<ul>
-<li>The <a href="LangRef.html#i_shufflevector">shufflevector</a> instruction
-has been generalized to allow different shuffle mask width than its input
-vectors. This allows you to use shufflevector to combine two
-"<4 x float>" vectors into a "<8 x float>" for example.</li>
-
-<li>LLVM IR now supports new intrinsics for computing and acting on <a
-href="LangRef.html#int_overflow">overflow of integer operations</a>. This allows
-efficient code generation for languages that must trap or throw an exception on
-overflow. While these intrinsics work on all targets, they only generate
-efficient code on X86 so far.</li>
-
-<li>LLVM IR now supports a new <a href="LangRef.html#linkage">private
-linkage</a> type to produce labels that are stripped by the assembler before it
-produces a .o file (thus they are invisible to the linker).</li>
-
-<li>LLVM IR supports two new attributes for better alias analysis. The <a
-href="LangRef.html#paramattrs">noalias</a> attribute can now be used on the
-return value of a function to indicate that it returns new memory (e.g.
-'malloc', 'calloc', etc).</li>
-
-<li>The new <a href="LangRef.html#paramattrs">nocapture</a> attribute can be
-used on pointer arguments to functions that access through but do not return the
-pointer in a data structure that out lives the call (e.g. 'strlen', 'memcpy',
-and many others). The simplifylibcalls pass applies these attributes to
-standard libc functions.</li>
-
-<li>The parser for ".ll" files in lib/AsmParser is now completely rewritten as a
-recursive descent parser. This parser produces better error messages (including
-caret diagnostics) is less fragile (less likely to crash on strange things) does
-not leak memory, is more efficient, and eliminates LLVM's last use of the
-'bison' tool.</li>
-
-<li>Debug information representation and manipulation internals have been
- consolidated to use a new set of classes in
- <tt>llvm/Analysis/DebugInfo.h</tt> classes. These routines are more
- efficient, robust, and extensible and replace the older mechanisms.
- llvm-gcc, clang, and the code generator now use them to create and process
- debug information.</li>
-
+<li>...</li>
</ul>
</div>
<div class="doc_text">
-<p>In addition to a huge array of bug fixes and minor performance tweaks, this
+<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>The loop optimizer now improves floating point induction variables in
-several ways, including adding shadow induction variables to avoid
-"integer <-> floating point" conversions in loops when safe.</li>
+<li>...</li>
+
+</ul>
+
+<p>Also, -anders-aa was removed</p>
-<li>The "-mem2reg" pass is now much faster on code with huge basic blocks.</li>
+</div>
-<li>The "-jump-threading" pass is more powerful: it is iterative
- and handles threading based on values with fully and partially redundant
- loads.</li>
-<li>The "-memdep" memory dependence analysis pass (used by GVN and memcpyopt) is
- both faster and more aggressive.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="executionengine">Interpreter and JIT Improvements</a>
+</div>
-<li>The "-scalarrepl" scalar replacement of aggregates pass is more aggressive
- about promoting unions to registers.</li>
+<div class="doc_text">
+<ul>
+<li>The JIT now <a
+href="http://llvm.org/viewvc/llvm-project?view=rev&revision=85295">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>
it run faster:</p>
<ul>
-<li>The <a href="WritingAnLLVMBackend.html">Writing an LLVM Compiler
-Backend</a> document has been greatly expanded and is substantially more
-complete.</li>
-
-<li>The SelectionDAG type legalization logic has been completely rewritten, is
-now more powerful (it supports arbitrary precision integer types for example),
-and more correct in several corner cases. The type legalizer converts
-operations on types that are not natively supported by the target machine into
-equivalent code sequences that only use natively supported types. The old type
-legalizer is still available (for now) and will be used if
-<tt>-disable-legalize-types</tt> is passed to the code generator.
-</li>
-<li>The code generator now supports widening illegal vectors to larger legal
-ones (for example, converting operations on <3 x float> to work on
-<4 x float>) which is very important for common graphics
-applications.</li>
-
-<li>The assembly printers for each target are now split out into their own
-libraries that are separate from the main code generation logic. This reduces
-code size of JIT compilers by not requiring them to be linked in.</li>
-
-<li>The 'fast' instruction selection path (used at -O0 and for fast JIT
- compilers) now supports accelerating codegen for code that uses exception
- handling constructs.</li>
-
-<li>The optional PBQP register allocator now supports register coalescing.</li>
+<li>...</li>
</ul>
</div>
</p>
<ul>
-<li>The <tt><a href="LangRef.html#int_returnaddress">llvm.returnaddress</a></tt>
-intrinsic (which is used to implement <tt>__builtin_return_address</tt>) now
-supports non-zero stack depths on X86.</li>
-
-<li>The X86 backend now supports code generation of vector shift operations
-using SSE instructions.</li>
-
-<li>X86-64 code generation now takes advantage of red zone, unless the
-<tt>-mno-red-zone</tt> option is specified.</li>
-
-<li>The X86 backend now supports using address space #256 in LLVM IR as a way of
-performing memory references off the GS segment register. This allows a
-front-end to take advantage of very low-level programming techniques when
-targeting X86 CPUs. See <tt>test/CodeGen/X86/movgs.ll</tt> for a simple
-example.</li>
-
-<li>The X86 backend now supports a <tt>-disable-mmx</tt> command line option to
- prevent use of MMX even on chips that support it. This is important for cases
- where code does not contain the proper <tt>llvm.x86.mmx.emms</tt>
- intrinsics.</li>
-
-<li>The X86 JIT now detects the new Intel <a
- href="http://en.wikipedia.org/wiki/Intel_Core_i7">Core i7</a> and <a
- href="http://en.wikipedia.org/wiki/Intel_Atom">Atom</a> chips;
- auto-configuring itself appropriately for the features of these chips.</li>
-
-<li>The JIT now supports exception handling constructs on Linux/X86-64 and
- Darwin/x86-64.</li>
-
-<li>The JIT supports Thread Local Storage (TLS) on Linux/X86-32 but not yet on
- X86-64.</li>
+
+<li>...</li>
+
</ul>
</div>
</p>
<ul>
-<li>Both direct and indirect load/stores work now.</li>
-<li>Logical, bitwise and conditional operations now work for integer data
-types.</li>
-<li>Function calls involving basic types work now.</li>
-<li>Support for integer arrays.</li>
-<li>Compiler can now emit libcalls for operations not supported by m/c
-instructions.</li>
-<li>Support for both data and ROM address spaces.</li>
+<li>...</li>
</ul>
<p>Things not yet supported:</p>
<ul>
-<li>Floating point.</li>
-<li>Passing/returning aggregate types to and from functions.</li>
<li>Variable arguments.</li>
-<li>Indirect function calls.</li>
<li>Interrupts/programs.</li>
-<li>Debug info.</li>
</ul>
</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="ARM">ARM Target Improvements</a>
+</div>
+
+<div class="doc_text">
+<p>New features of the ARM target include:
+</p>
+
+<ul>
+
+<li>...</li>
+</ul>
+
+
+</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="llvmc">Improvements in LLVMC</a>
+<a name="OtherTarget">Other Target Specific Improvements</a>
</div>
<div class="doc_text">
-<p>New features include:</p>
+<p>New features of other targets include:
+</p>
<ul>
-<li>Beginning with LLVM 2.5, <tt>llvmc2</tt> is known as
- just <tt>llvmc</tt>. The old <tt>llvmc</tt> driver was removed.</li>
+<li>...</li>
+</ul>
+
+</div>
-<li>The Clang plugin was substantially improved and is now enabled
- by default. The command <tt>llvmc --clang</tt> can be now used as a
- synonym to <tt>ccc</tt>.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="newapis">New Useful APIs</a>
+</div>
-<li>There is now a <tt>--check-graph</tt> option, which is supposed to catch
- common errors like multiple default edges, mismatched output/input language
- names and cycles. In general, these checks can't be done at compile-time
- because of the need to support plugins.</li>
+<div class="doc_text">
-<li>Plugins are now more flexible and can refer to compilation graph nodes and
- options defined in other plugins. To manage dependencies, a priority-sorting
- mechanism was introduced. This change affects the TableGen file syntax. See the
- documentation for details.</li>
+<p>This release includes a number of new APIs that are used internally, which
+ may also be useful for external clients.
+</p>
-<li>Hooks can now be provided with arguments. The syntax is "<tt>$CALL(MyHook,
- 'Arg1', 'Arg2', 'Arg3')</tt>".</li>
+<ul>
+<li>...</li>
+</ul>
-<li>A new option type: multi-valued option, for options that take more than one
- argument (for example, "<tt>-foo a b c</tt>").</li>
-<li>New option properties: '<tt>one_or_more</tt>', '<tt>zero_or_more</tt>',
-'<tt>hidden</tt>' and '<tt>really_hidden</tt>'.</li>
+</div>
-<li>The '<tt>case</tt>' expression gained an '<tt>error</tt>' action and
- an '<tt>empty</tt>' test (equivalent to "<tt>(not (not_empty ...))</tt>").</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="otherimprovements">Other Improvements and New Features</a>
+</div>
-<li>Documentation now looks more consistent to the rest of the LLVM
- docs. There is also a man page now.</li>
+<div class="doc_text">
+<p>Other miscellaneous features include:</p>
+<ul>
+<li>...</li>
</ul>
</div>
<div class="doc_text">
<p>If you're already an LLVM user or developer with out-of-tree changes based
-on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
+on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
from the previous release.</p>
<ul>
-
-<li>llvm-gcc defaults to <tt>-fno-math-errno</tt> on all X86 targets.</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>
API changes are:</p>
<ul>
-<li>Some deprecated interfaces to create <tt>Instruction</tt> subclasses, that
- were spelled with lower case "create", have been removed.</li>
+<li><tt>ModuleProvider</tt> has been <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
+<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
+functions that used to accept <tt>ModuleProvider</tt>. Clients who
+wrote their own <tt>ModuleProvider</tt>s will need to derive from
+<tt>GVMaterializer</tt> instead and use
+<tt>Module::setMaterializer</tt> to attach it to a
+<tt>Module</tt>.</li>
+
+<li><tt>GhostLinkage</tt> has given up the ghost.
+<tt>GlobalValue</tt>s that have not yet been read from their backing
+storage have the same linkage they will have after being read in.
+Clients must replace calls to
+<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>
</ul>
</div>
<ul>
<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
-Linux, Fedora Core and FreeBSD (and probably other unix-like systems).</li>
+ 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
-and 64-bit modes.</li>
+ 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 10.</li>
+<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
<li>Alpha-based machines running Debian GNU/Linux.</li>
-<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
</ul>
<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</p>
+<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>.
+However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
+for x86/x86-64 has been made available from the third party AuroraUX Project
+that has been meticulously tested for bootstrapping LLVM & Clang.</li>
+</ul>
+
</div>
<!-- ======================================================================= -->
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
+<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
+ backends are experimental.</li>
<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
- supported value for this option.</li>
+ supported value for this option. The MachO writer is experimental, and
+ works much better in mainline SVN.</li>
</ul>
</div>
<li>The X86 backend generates inefficient floating point code when configured
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 mingw64 runtime
- currently due
+ 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> due to lack of support for the
- 'u' inline assembly constraint and X87 floating point inline assembly.</li>
+ <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>
<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
argument constructs on X86-64 by lowering them manually.</li>
<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>
-<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
+<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
</li>
-<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly
- execute
-programs compiled with LLVM. Please use more recent versions of QEMU.</li>
</ul>
</div>
<div class="doc_text">
<ul>
-<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
+<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 class="doc_text">
<ul>
-<li>The O32 ABI is not fully supported.</li>
<li>64-bit MIPS targets are not supported yet.</li>
</ul>
</ul>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ia64-be">Known problems with the IA64 back-end</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
-<li>The Itanium backend is highly experimental, and has a number of known
- issues. We are looking for a maintainer for the Itanium backend. If you
- are interested, please contact the LLVMdev mailing list.</li>
-</ul>
-
-</div>
-
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="c-be">Known problems with the C back-end</a>
<!-- ======================================================================= -->
<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">
-<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
-Optimization</a> on most platforms "out-of-the-box". Please inquire on the
-LLVMdev mailing list if you are interested.</p>
-
<p>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
</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>
-
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
<div class="doc_text">
<ul>
<li>Fortran support generally works, but there are still several unresolved bugs
- in Bugzilla. Please see the tools/gfortran component for details.</li>
-
-<li>The Fortran front-end currently does not build on Darwin (without tweaks)
- due to unresolved dependencies on the C front-end.</li>
+ in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
+ tools/gfortran component for details.</li>
</ul>
</div>
</div>
<div class="doc_text">
-The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
-technology and problems should be expected.
+The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
+technology, and problems should be expected.
<ul>
<li>The Ada front-end currently only builds on X86-32. This is mainly due
-to lack of trampoline support (pointers to nested functions) on other platforms,
-
however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
+to lack of trampoline support (pointers to nested functions) on other platforms.
+
However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
which does support trampolines.</li>
<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
exception handling, which is used internally by the compiler.
-Workaround: configure with --disable-bootstrap.</li>
+Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
(c380004 also fails with gcc-4.2 mainline).
If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
causes the compiler to go into an infinite loop, using up all system memory.</li>
-<li>Some gcc specific Ada tests continue to crash the compiler.</li>
-<li>The -E binder option (exception backtraces)
+<li>Some GCC specific Ada tests continue to crash the compiler.</li>
+<li>The <tt>-E</tt> binder option (exception backtraces)
<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
-crashing if an exception is raised. Workaround: do not use -E.</li>
+crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
or finish at a non-byte offset</a> in a record. Workaround: do not pack records
or use representation clauses that result in a field of a non-discrete type
</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>
projects / oota-llvm.git / blobdiff