<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.6 Release Notes</title>
+ <title>LLVM 2.7 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.6 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 2.6</a></li>
- <li><a href="#whatsnew">What's New in LLVM 2.6?</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 2.6. 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>
+
+<p>FIXME: llvm.org moved to new server, mention new logo, Ted and Doug new code
+ owners.</p>
+
</div>
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.
-->
-<!-- Unfinished features in 2.6:
+<!-- Features that need text if they're finished for 2.7:
gcc plugin.
strong phi elim
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:
compiler_rt
KLEE web page at klee.llvm.org
Many new papers added to /pubs/
- Mention gcc plugin.
-
+ Mention gcc plugin.
-->
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
-The LLVM 2.6 distribution currently consists of code from the core LLVM
+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
<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 C family of languages.
-LLVM 2.6 is the first release to officially include Clang, and it provides a
-production quality C and Objective-C compiler. If you are interested in <a
-href="http://clang.llvm.org/performance.html">fast compiles</a> and
-<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
-encourage you to try it out. Clang currently compiles typical Objective-C code
-3x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
-(which is when the most pressure is on the frontend).</p>
-
-<p>In addition to supporting these languages, C++ support is also <a
-href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
-Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
-If you are interested in Clang C++ support or any other Clang feature, we
-strongly encourage you to get involved on the <a
-href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
-list</a>.</p>
-
-<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
+<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
+
+<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
<ul>
-<li>C and Objective-C support are now considered production quality.</li>
-<li>AuroraUX, FreeBSD and OpenBSD are now supported.</li>
-<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
-<li>Many many bugs are fixed and lots of features have been added.</li>
+<li>FIXME: C++! Include a link to cxx_compatibility.html</li>
+
+<li>FIXME: Static Analyzer improvements?</li>
+
+<li>CIndex API and Python bindings: Clang now includes a C API as part of the
+CIndex library. Although we make 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 includings an 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 a beta quality ARM compiler.</li>
</ul>
</div>
<div class="doc_text">
-<p>Previously announced in the 2.4 and 2.5 LLVM releases, 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 checks to find
bugs that occur on a specific path within a program.</p>
-<p>In the LLVM 2.6 time-frame, the analyzer core has undergone several important
-improvements and cleanups and now includes a new <em>Checker</em> interface that
-is intended to eventually serve as a basis for domain-specific checks. Further,
-in addition to generating HTML files for reporting analysis results, the
-analyzer can now also emit bug reports in a structured XML format that is
-intended to be easily readable by other programs.</p>
-
-<p>The set of checks performed by the static analyzer continues 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>
compilation.</p>
<p>
-VMKit version 0.26 builds with LLVM 2.6 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>A new llcj tool to generate shared libraries or executables of Java
- files.</li>
-<li>Cooperative garbage collection. </li>
-<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
-<li>Implementation of a two-word header for Java objects instead of the original
- three-word header. </li>
-<li>Better Java specification-compliance: division by zero checks, stack
- overflow checks, finalization and references support. </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>
<!--=========================================================================-->
<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>
-
-</div>
+<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 class="doc_subsection">
-<a name="dragonegg">DragonEgg: GCC-4.5 as an LLVM frontend</a>
-</div>
+<p>
+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.
+</p>
-<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 uses the new gcc plugin architecture to
-disable the GCC optimizers and code generators, and schedule the LLVM optimizers
-and code generators (or direct output of LLVM IR) instead. Currently only Linux
-and Darwin are supported, and only on x86-32 and x86-64. It should be easy to
-add additional unix-like architectures and other processor families. In theory
-it should be possible to use <a href="http://dragonegg.llvm.org/">DragonEgg</a>
-with any language supported by gcc, however only C and Fortran work well for the
-moment. Ada and C++ work to some extent, while Java, Obj-C and Obj-C++ are so
-far entirely untested. Since gcc-4.5 has not yet been released, neither has
-<a href="http://dragonegg.llvm.org/">DragonEgg</a>. To build
-<a href="http://dragonegg.llvm.org/">DragonEgg</a> you will need to check out the
-development versions of <a href="http://gcc.gnu.org/svn.html/"> gcc</a>,
-<a href="http://llvm.org/docs/GettingStarted.html#checkout">llvm</a> and
-<a href="http://dragonegg.llvm.org/">DragonEgg</a> from their respective
-subversion repositories, and follow the instructions in the
-<a href="http://dragonegg.llvm.org/">DragonEgg</a> README.
+DragonEgg has not yet been released. Once gcc-4.5 has been released, dragonegg
+will probably be released as part of the following LLVM release.
</p>
</div>
<div class="doc_text">
<p>
-The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
-better tools for dealing with machine code, object file formats, etc. The idea
-is to be able to generate most of the target specific details of assemblers and
-disassemblers from existing LLVM target .td files (with suitable enhancements),
-and to build infrastructure for reading and writing common object file formats.
-One of the first deliverables is to build a full assembler and integrate it into
-the compiler, which is predicted to substantially reduce compile time in some
-scenarios.
-</p>
-
-<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
-can reliably parse and pretty print (with some encoding information) a
-darwin/x86 .s file successfully, and has the very early phases of a Mach-O
-assembler in progress. Beyond the MC framework itself, major refactoring of the
-LLVM code generator has started. The idea is to make the code generator reason
-about the code it is producing in a much more semantic way, rather than a
-textual way. For example, the code generator now uses MCSection objects to
-represent section assignments, instead of text strings that print to .section
-directives.</p>
-
-<p>MC is an early and ongoing project that will hopefully continue to lead to
-many improvements in the code generator and build infrastructure useful for many
-other situations.
+The LLVM Machine Code (MC) Toolkit project is ...
</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="externalproj">External Open Source Projects Using LLVM 2.6</a>
+ <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
</div>
<!-- *********************************************************************** -->
<p>An exciting aspect of LLVM is that it is used as an enabling technology for
a lot of other language and tools projects. This section lists some of the
- projects that have already been updated to work with LLVM 2.6.</p>
+ projects that have already been updated to work with LLVM 2.7.</p>
</div>
</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
<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_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
<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>
+handling.--> </p>
</div>
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 0.31 and later have been tested and are known to work with
-LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
-</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.
The LDC project works great with the LLVM 2.6 release. General improvements in
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.
+fully featured as the original DMD compiler from DigitalMars.-->
</p>
</div>
<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>
<!--=========================================================================-->
<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_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>
+code.-->
+</p>
</div>
<!--=========================================================================-->
<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.
+code.-->
</p>
</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="tce">TTA-based Codesign Environment (TCE)</a>
+</div>
+
+<div class="doc_text">
+<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>
+
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="whatsnew">What's New in LLVM 2.6?</a>
+ <a name="whatsnew">What's New in LLVM 2.7?</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
-<p>LLVM 2.6 includes several major new capabilities:</p>
+<p>LLVM 2.7 includes several major new capabilities:</p>
<ul>
-<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>
- and <a href="#mc">machine code toolkit</a> sub-projects.</li>
-<li>Debug information now includes line numbers when optimizations are enabled.
- This allows statistical sampling tools like OProfile and Shark to map
- samples back to source lines.</li>
-<li>LLVM now includes new experimental backends to support the MSP430, SystemZ
- and BlackFin architectures.</li>
-<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
- enables support for <a href="LinkTimeOptimization.html">transparent
- link-time optimization</a> on ELF targets when used with the Gold binutils
- linker.</li>
-<li>LLVM now supports doing optimization and code generation on multiple
- threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
- Programmer's Manual</a> for more information.</li>
-<li>LLVM now has experimental support for <a
- href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
- metadata</a> in LLVM IR, though the implementation is not guaranteed to be
- final and the .bc file format may change in future releases. Debug info
- does not yet use this format in LLVM 2.6.</li>
+<li>...</li>
</ul>
+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, along with LowerAllocations pass.
+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. ?
+
+The ARM backend now has good support for ARMv4 backend (tested on StrongARM
+ hardware), previously only supported ARMv4T and newer.
+
+
+
+Defaults to RTTI off, packagers should build with make REQUIRE_RTTI=1.
+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>
<!--=========================================================================-->
expose new optimization opportunities:</p>
<ul>
-<li>The <a href="LangRef.html#i_add">add</a>, <a
- href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
- instructions have been split into integer and floating point versions (like
- divide and remainder), introducing new <a
- href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
- and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
-<li>The <a href="LangRef.html#i_add">add</a>, <a
- href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
- instructions now support optional "nsw" and "nuw" bits which indicate that
- the operation is guaranteed to not overflow (in the signed or
- unsigned case, respectively). This gives the optimizer more information and
- can be used for things like C signed integer values, which are undefined on
- overflow.</li>
-<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
- optional "exact" flag which indicates that the result of the division is
- guaranteed to have a remainder of zero. This is useful for optimizing pointer
- subtraction in C.</li>
-<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
- supports arbitrary integer index values for array/pointer indices. This
- allows for better code generation on 16-bit pointer targets like PIC16.</li>
-<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
- supports an "inbounds" optimization hint that tells the optimizer that the
- pointer is guaranteed to be within its allocated object.</li>
-<li>LLVM now support a series of new linkage types for global values which allow
- for better optimization and new capabilities:
- <ul>
- <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
- <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
- semantics as the non-"odr" linkage types. The difference is that these
- linkage types indicate that all definitions of the specified function
- are guaranteed to have the same semantics. This allows inlining
- templates functions in C++ but not inlining weak functions in C,
- which previously both got the same linkage type.</li>
- <li><a href="LangRef.html#linkage_available_externally">available_externally
- </a> is a new linkage type that gives the optimizer visibility into the
- definition of a function (allowing inlining and side effect analysis)
- but that does not cause code to be generated. This allows better
- optimization of "GNU inline" functions, extern templates, etc.</li>
- <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
- new linkage type (which is only useful on Mac OS X) that is used for
- some metadata generation and other obscure things.</li>
- </ul></li>
-<li>Finally, target-specific intrinsics can now return multiple values, which
- is useful for modeling target operations with multiple results.</li>
+<li>...</li>
</ul>
</div>
<ul>
-<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
- pass has many improvements that allow it to better promote vector unions,
- variables which are memset, and much more strange code that can happen to
- do bitfield accesses to register operations. An interesting change is that
- it now produces "unusual" integer sizes (like i1704) in some cases and lets
- other optimizers clean things up.</li>
-<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
- promotes small integer induction variables to 64-bit on 64-bit targets,
- which provides a major performance boost for much numerical code. It also
- promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
- expressions (e.g. getelementptrs), as well as integers.</li>
-<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
- redundancies of loads in simple cases.</li>
-<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
- inlining similar arrays from multiple callees into one caller.</li>
-<li>LLVM includes a new experimental Static Single Information (SSI)
- construction pass.</li>
+<li>...</li>
</ul>
+<p>Also, -anders-aa was removed</p>
+
</div>
<div class="doc_text">
<ul>
-<li>LLVM has a new "EngineBuilder" class which makes it more obvious how to
- set up and configure an ExecutionEngine (a JIT or interpreter).</li>
-<li>The JIT now supports generating more than 16M of code.</li>
-<li>When configured with <tt>--with-oprofile</tt>, the JIT can now inform
- OProfile about JIT'd code, allowing OProfile to get line number and function
- name information for JIT'd functions.</li>
-<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
- calling almost arbitrary external (natively compiled) functions.</li>
-<li>Clients of the JIT can now register a 'JITEventListener' object to receive
- callbacks when the JIT emits or frees machine code. The OProfile support
- uses this mechanism.</li>
+<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>
<ul>
-<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc as <tt>-dA</tt>
- and clang as <tt>-fverbose-asm</tt> or <tt>-dA</tt>) now adds a lot of
- useful information in comments to
- the generated .s file. This information includes location information (if
- built with <tt>-g</tt>) and loop nest information.</li>
-<li>The code generator now supports a new MachineVerifier pass which is useful
- for finding bugs in targets and codegen passes.</li>
-<li>The Machine LICM is now enabled by default. It hoists instructions out of
- loops (such as constant pool loads, loads from read-only stubs, vector
- constant synthesization code, etc.) and is currently configured to only do
- so when the hoisted operation can be rematerialized.</li>
-<li>The Machine Sinking pass is now enabled by default. This pass moves
- side-effect free operations down the CFG so that they are executed on fewer
- paths through a function.</li>
-<li>The code generator now performs "stack slot coloring" of register spills,
- which allows spill slots to be reused. This leads to smaller stack frames
- in cases where there are lots of register spills.</li>
-<li>The register allocator has many improvements to take better advantage of
- commutable operations, various spiller peephole optimizations, and can now
- coalesce cross-register-class copies.</li>
-<li>Tblgen now supports multiclass inheritance and a number of new string and
- list operations like <tt>!(subst)</tt>, <tt>!(foreach)</tt>, <tt>!car</tt>,
- <tt>!cdr</tt>, <tt>!null</tt>, <tt>!if</tt>, <tt>!cast</tt>.
- These make the .td files more expressive and allow more aggressive factoring
- of duplication across instruction patterns.</li>
-<li>Target-specific intrinsics can now be added without having to hack VMCore to
- add them. This makes it easier to maintain out-of-tree targets.</li>
-<li>The instruction selector is better at propagating information about values
- (such as whether they are sign/zero extended etc.) across basic block
- boundaries.</li>
-<li>The SelectionDAG datastructure has new nodes for representing buildvector
- and <a href="http://llvm.org/PR2957">vector shuffle</a> operations. This
- makes operations and pattern matching more efficient and easier to get
- right.</li>
-<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
- the "shrink wrapping" optimization, which moves spills and reloads around in
- the CFG to avoid doing saves on paths that don't need them.</li>
-<li>LLVM includes new experimental support for writing ELF .o files directly
- from the compiler. It works well for many simple C testcases, but doesn't
- support exception handling, debug info, inline assembly, etc.</li>
-<li>Targets can now specify register allocation hints through
- <tt>MachineRegisterInfo::setRegAllocationHint</tt>. A regalloc hint consists
- of hint type and physical register number. A hint type of zero specifies a
- register allocation preference. Other hint type values are target specific
- which are resolved by <tt>TargetRegisterInfo::ResolveRegAllocHint</tt>. An
- example is the ARM target which uses register hints to request that the
- register allocator provide an even / odd register pair to two virtual
- registers.</li>
+<li>...</li>
</ul>
</div>
<ul>
-<li>SSE 4.2 builtins are now supported.</li>
-<li>GCC-compatible soft float modes are now supported, which are typically used
- by OS kernels.</li>
-<li>X86-64 now models implicit zero extensions better, which allows the code
- generator to remove a lot of redundant zexts. It also models the 8-bit "H"
- registers as subregs, which allows them to be used in some tricky
- situations.</li>
-<li>X86-64 now supports the "local exec" and "initial exec" thread local storage
- model.</li>
-<li>The vector forms of the <a href="LangRef.html#i_icmp">icmp</a> and <a
- href="LangRef.html#i_fcmp">fcmp</a> instructions now select to efficient
- SSE operations.</li>
-<li>Support for the win64 calling conventions have improved. The primary
- missing feature is support for varargs function definitions. It seems to
- work well for many win64 JIT purposes.</li>
-<li>The X86 backend has preliminary support for <a
- href="CodeGenerator.html#x86_memory">mapping address spaces to segment
- register references</a>. This allows you to write GS or FS relative memory
- accesses directly in LLVM IR for cases where you know exactly what you're
- doing (such as in an OS kernel). There are some known problems with this
- support, but it works in simple cases.</li>
-<li>The X86 code generator has been refactored to move all global variable
- reference logic to one place
- (<tt>X86Subtarget::ClassifyGlobalReference</tt>) which
- makes it easier to reason about.</li>
+<li>...</li>
</ul>
</p>
<ul>
-<li>Support for floating-point, indirect function calls, and
- passing/returning aggregate types to functions.
-<li>The code generator is able to generate debug info into output COFF files.
-<li>Support for placing an object into a specific section or at a specific
- address in memory.</li>
+<li>...</li>
</ul>
<p>Things not yet supported:</p>
<ul>
-<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
-that implement version v7-A of the ARM architecture. The ARM backend now
-supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.</li>
-
-<li>The AAPCS-VFP "hard float" calling conventions are also supported with the
-<tt>-float-abi=hard</tt> flag.</li>
-
-<li>The ARM calling convention code is now tblgen generated instead of resorting
- to C++ code.</li>
+<li>...</li>
</ul>
-<p>These features are still somewhat experimental
-and subject to change. The Neon intrinsics, in particular, may change in future
-releases of LLVM. ARMv7 support has progressed a lot on top of tree since 2.6
-branched.</p>
-
</div>
</p>
<ul>
-<li>Mips now supports O32 Calling Convention.</li>
-<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
- support, lots of bugs fixed.</li>
-<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
- Needs more testing.</li>
+<li>...</li>
</ul>
</div>
</p>
<ul>
-<li>New <a href="http://llvm.org/doxygen/PrettyStackTrace_8h-source.html">
- <tt>PrettyStackTrace</tt> class</a> allows crashes of llvm tools (and applications
- that integrate them) to provide more detailed indication of what the
- compiler was doing at the time of the crash (e.g. running a pass).
- At the top level for each LLVM tool, it includes the command line arguments.
- </li>
-<li>New <a href="http://llvm.org/doxygen/StringRef_8h-source.html">StringRef</a>
- and <a href="http://llvm.org/doxygen/Twine_8h-source.html">Twine</a> classes
- make operations on character ranges and
- string concatenation to be more efficient. <tt>StringRef</tt> is just a <tt>const
- char*</tt> with a length, <tt>Twine</tt> is a light-weight rope.</li>
-<li>LLVM has new <tt>WeakVH</tt>, <tt>AssertingVH</tt> and <tt>CallbackVH</tt>
- classes, which make it easier to write LLVM IR transformations. <tt>WeakVH</tt>
- is automatically drops to null when the referenced <tt>Value</tt> is deleted,
- and is updated across a <tt>replaceAllUsesWith</tt> operation.
- <tt>AssertingVH</tt> aborts the program if the
- referenced value is destroyed while it is being referenced. <tt>CallbackVH</tt>
- is a customizable class for handling value references. See <a
- href="http://llvm.org/doxygen/ValueHandle_8h-source.html">ValueHandle.h</a>
- for more information.</li>
-<li>The new '<a href="http://llvm.org/doxygen/Triple_8h-source.html">Triple
- </a>' class centralizes a lot of logic that reasons about target
- triples.</li>
-<li>The new '<a href="http://llvm.org/doxygen/ErrorHandling_8h-source.html">
- llvm_report_error()</a>' set of APIs allows tools to embed the LLVM
- optimizer and backend and recover from previously unrecoverable errors.</li>
-<li>LLVM has new abstractions for <a
- href="http://llvm.org/doxygen/Atomic_8h-source.html">atomic operations</a>
- and <a href="http://llvm.org/doxygen/RWMutex_8h-source.html">reader/writer
- locks</a>.</li>
-<li>LLVM has new <a href="http://llvm.org/doxygen/SourceMgr_8h-source.html">
- <tt>SourceMgr</tt> and <tt>SMLoc</tt> classes</a> which implement caret
- diagnostics and basic include stack processing for simple parsers. It is
- used by tablegen, llvm-mc, the .ll parser and FileCheck.</li>
+<li>...</li>
</ul>
<p>Other miscellaneous features include:</p>
<ul>
-<li>LLVM now includes a new internal '<a
- href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
- writing much more accurate regression tests that run faster. Please see the
- <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
- Guide</a> for more information.</li>
-<li>LLVM profile information support has been significantly improved to produce
-correct use counts, and has support for edge profiling with reduced runtime
-overhead. Combined, the generated profile information is both more correct and
-imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
-CPU2000).</li>
-<li>The C bindings (in the llvm/include/llvm-c directory) include many newly
- supported APIs.</li>
-<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
- programming language.</li>
-
-<li>The LLVMC driver has several new features:
- <ul>
- <li>Dynamic plugins now work on Windows.</li>
- <li>New option property: init. Makes possible to provide default values for
- options defined in plugins (interface to <tt>cl::init</tt>).</li>
- <li>New example: Skeleton, shows how to create a standalone LLVMC-based
- driver.</li>
- <li>New example: mcc16, a driver for the PIC16 toolchain.</li>
- </ul>
-</li>
-
+<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 2.5, 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>The Itanium (IA64) backend has been removed. It was not actively supported
- and had bitrotted.</li>
-<li>The BigBlock register allocator has been removed, it had also bitrotted.</li>
-<li>The C Backend (<tt>-march=c</tt>) is no longer considered part of the LLVM release
-criteria. We still want it to work, but no one is maintaining it and it lacks
-support for arbitrary precision integers and other important IR features.</li>
-
-<li>All LLVM tools now default to overwriting their output file, behaving more
- like standard unix tools. Previously, this only happened with the '<tt>-f</tt>'
- option.</li>
-<li>LLVM build now builds all libraries as .a files instead of some
- libraries as relinked .o files. This requires some APIs like
- InitializeAllTargets.h.
- </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>All uses of <tt>hash_set</tt> and <tt>hash_map</tt> have been removed from
- the LLVM tree and the wrapper headers have been removed.</li>
-<li>The llvm/Streams.h and <tt>DOUT</tt> member of Debug.h have been removed. The
- <tt>llvm::Ostream</tt> class has been completely removed and replaced with
- uses of <tt>raw_ostream</tt>.</li>
-<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
- been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
- now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
- for clients that will only ever use a single context, the new
- <tt>getGlobalContext()</tt> API can be used to access a default global
- context which can be passed in any and all cases where a context is
- required.
-<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
-<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
- overloaded for floating-point types. Floating-point addition, subtraction
- and multiplication are now represented with new operators <tt>FAdd</tt>,
- <tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
- <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
- <tt>CreateNeg</tt> should only be used for integer arithmetic now;
- <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
- <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
-<li>The <tt>DynamicLibrary</tt> class can no longer be constructed, its functionality has
- moved to static member functions.</li>
-<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
- takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
- <tt>false</tt>, an error will be reported if a file with the given name
- already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
- be silently truncated (which is the behavior before this flag was
- added).</li>
-<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
- longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt>
- should be used.</li>
-
-<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
-and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
-or <tt>std::string</tt>, as described in
-the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
-clients should be unaffected by this transition, unless they are used to
-<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
-2.6:
- <ul>
- <li><tt>getNameStr()</tt> is still available, and matches the old
- behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
- although more efficient alternatives are now possible.</li>
-
- <li>If you were just relying on <tt>getName()</tt> being able to be sent to
- a <tt>std::ostream</tt>, consider migrating
- to <tt>llvm::raw_ostream</tt>.</li>
-
- <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
- char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
- Note that this string (as before), may not be the entire name if the
- name contains embedded null characters.</li>
-
- <li>If you were using <tt>operator +</tt> on the result of <tt>getName()</tt> and
- treating the result as an <tt>std::string</tt>, you can either
- use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
- could move to a <tt>Twine</tt> based design.</li>
-
- <li><tt>isName()</tt> should be replaced with comparison
- against <tt>getName()</tt> (this is now efficient).
- </ul>
-</li>
-
-<li>The registration interfaces for backend Targets has changed (what was
-previously <tt>TargetMachineRegistry</tt>). For backend authors, see the <a
-href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
-guide. For clients, the notable API changes are:
- <ul>
- <li><tt>TargetMachineRegistry</tt> has been renamed
- to <tt>TargetRegistry</tt>.</li>
-
- <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
- function to find targets.</li>
- </ul>
-</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>
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 for 2.6 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>.
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 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. The ELF writer is experimental.</li>
-<li>The implementation of Andersen's Alias Analysis has many known bugs.</li>
+ supported value for this option. The MachO writer is experimental, and
+ works much better in mainline SVN.</li>
</ul>
</div>
<!-- ======================================================================= -->
<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">
</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>
</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