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- <title>LLVM 2.1 Release Notes</title>
+ <title>LLVM 2.2 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.1 Release Notes</div>
+<div class="doc_title">LLVM 2.2 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</a></li>
<p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
</div>
+<h1><font color="red">THIS IS A WORK IN PROGRESS FOR THE LLVM 2.2
+RELEASE</font</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 2.1. Here we describe the status of LLVM, including
+infrastructure, release 2.2. Here we describe the status of LLVM, including
major improvements from the previous release and any known problems. All LLVM
releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
releases web site</a>.</p>
<div class="doc_text">
-<p>This is the twelfth public release of the LLVM Compiler Infrastructure.
-It includes many features and refinements from LLVM 2.0.</p>
+<p>This is the thirteenth public release of the LLVM Compiler Infrastructure.
+It includes many features and refinements from LLVM 2.1.</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="frontends">New Frontends</a>
+<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
</div>
<div class="doc_text">
-<p>LLVM 2.1 brings two new beta C front-ends. First, a new version of llvm-gcc
-based on GCC 4.2, innovatively called "llvm-gcc-4.2". This promises to bring
-FORTRAN and Ada support to LLVM as well as features like atomic builtins and
-OpenMP. None of these actually work yet, but don't let that stop you checking
-it out!</p>
+<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
+LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
+has made leaps and bounds and is now at least as good as 4.0 in virtually every
+area, and is better in several areas (for example, exception handling
+correctness). We strongly recommend that you migrate from llvm-gcc 4.0 to
+llvm-gcc 4.2 in this release cycle because <b>LLVM 2.2 is the last release
+that will support llvm-gcc 4.0</b>: LLVM 2.3 will only support the llvm-gcc
+4.2 front-end.</p>
+
+<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. Currently, its C and Objective-C support is maturing
+nicely, and it has advanced source-to-source analysis and transformation
+capabilities. If you are interested in building source-level tools for C and
+Objective-C (and eventually C++), you should take a look. However, note that
+clang is not an official part of the LLVM 2.2 release. If you are interested in
+this project, please see the web site.</p>
+
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="majorfeatures">Major New Features</a>
+</div>
+
+<div class="doc_text">
+
+<p>Dale contributed full support for long double on x86/x86-64 (where it is 80
+bits) and on Darwin PPC/PPC64 (where it is 128 bits).</p>
+
+<p>Ada, gfortran</p>
+
+<p>
+debug improvements -O0
+EH.
+
+Gordon: GC Revamp. docs/GarbageCollection.html
+
+Kaleidescope: docs/tutorial
-<p>Second, LLVM now includes its own native C and Objective-C front-end (C++ is
-in progress, but is not very far along) code named "<a
-href="http://clang.llvm.org/">clang</a>". This front-end has a number of great
-features, primarily aimed at source-level analysis and speeding up compile-time.
-At this point though, the LLVM Code Generator component is still very early in
-development, so it's mostly useful for people looking to build source-level
-analysis tools or source-to-source translators.</p>
+Gordon: C and Ocaml Bindings
</div>
<ul>
-<li>Owen Anderson wrote the new MemoryDependenceAnalysis pass, which provides
- a lazy, caching layer on top of <a
- href="AliasAnalysis.html">AliasAnalysis</a>. He then used it to rewrite
- DeadStoreElimination which resulted in significantly better compile time in
- common cases, </li>
-<li>Owen implemented the new GVN pass, which is also based on
- MemoryDependenceAnalysis. This pass replaces GCSE/LoadVN in the standard
- set of passes, providing more aggressive optimization at a some-what
- improved compile-time cost.</li>
-<li>Owen implemented GVN-PRE, a partial redundancy elimination algorithm that
- shares some details with the new GVN pass. It is still in need of compile
- time tuning, and is not turned on by default.</li>
-<li>Devang merged ETForest and DomTree into a single easier to use data
- structure. This makes it more obvious which datastructure to choose
- (because there is only one) and makes the compiler more memory and time
- efficient (less stuff to keep up-to-date).</li>
-<li>Nick Lewycky improved loop trip count analysis to handle many more common
- cases.</li>
+<li>Daniel Berlin and (Curtis?) rewrote Andersen's alias analysis (which is not
+enabled by default) to be several orders of magnitude faster, implmented Offline
+Variable Substitution.</li>
+
+Devang: LoopIndexSplit is enabled by default.
</ul>
</div>
<div class="doc_text">
-<p>One of the main focuses of this release was performance tuning and bug
+<p>foci of this release was performance tuning and bug
fixing. In addition to these, several new major changes occurred:</p>
<ul>
-<li>Dale finished up the Tail Merging optimization in the code generator, and
- enabled it by default. This produces smaller code that is also faster in
- some cases.</li>
-
-<li>Christopher Lamb implemented support for virtual register sub-registers,
- which can be used to better model many forms of subregisters. As an example
- use, he modified the X86 backend to use this to model truncates and
- extends more accurately (leading to better code).</li>
-
-<li>Dan Gohman changed the way we represent vectors before legalization,
- significantly simplifying the SelectionDAG representation for these and
- making the code generator faster for vector code.</li>
-
-<li>Evan contributed a new target independent if-converter. While it is
- target independent, so far only the ARM backend uses it.</li>
+<li>Owen contributed Machine Loop info, domintors, etc. Merged dom and
+ postdom.</li>
-<li>Evan rewrite the way the register allocator handles rematerialization,
- allowing it to be much more effective on two-address targets like X86,
- and taught it to fold loads away when possible (also a big win on X86).</li>
+<li>Dan added support for emitting debug information with .file and .loc on
+targets that support it</li>
-<li>Dan Gohman contributed support for better alignment and volatility handling
- in the code generator, and significantly enhanced alignment analysis for SSE
- load/store instructions. With his changes, an insufficiently-aligned SSE
- load instruction turns into <tt>movups</tt>, for example.</li>
-
-<li>Duraid Madina contributed a new "bigblock" register allocator, and Roman
- Levenstein contributed several big improvements. BigBlock is optimized for
- code that uses very large basic blocks. It is slightly slower than the
- "local" allocator, but produces much better code.</li>
-
-<li>David Greene refactored the register allocator to split coalescing out from
- allocation, making coalescers pluggable.</li>
+<li>Evan physical register dependencies in the BURR scheduler</li>
+<li>Evan EXTRACT_SUBREG coalescing support</li>
</ul>
</div>
</p>
<ul>
-<li>Bruno Cardoso Lopes contributed initial MIPS support. It is sufficient to
- run many small programs, but is still incomplete and is not yet
- fully performant.</li>
-
-<li>Bill Wendling added SSSE3 support to the X86 backend.</li>
-
-<li>Nicholas Geoffray contributed improved linux/ppc ABI and JIT support.</li>
-
-<li>Dale Johannesen rewrote handling of 32-bit float values in the X86 backend
- when using the floating point stack, fixing several nasty bugs.</li>
-
-<li>Dan contributed rematerialization support for the X86 backend, in addition
- to several X86-specific micro optimizations.</li>
+<li>Evan X86 now models EFLAGS in instructions.</li>
+<li>Evan: If conversion on by default for ARM.</li>
+<li>Bruno: MIPS PIC support.</li>
+<li>Arnold Schwaighofer: X86 tail call support.</li>
</ul>
</div>
</p>
<ul>
-<li>Duncan and Anton made significant progress chasing down a number of problems
- with C++ Zero-Cost exception handling in llvm-gcc 4.0 and 4.2. It is now at
- the point where it "just works" on linux/X86-32 and has partial support on
- other targets.</li>
-
-<li>Devang and Duncan fixed a huge number of bugs relating to bitfields, pragma
- pack, and variable sized fields in structures.</li>
-
-<li>Tanya implemented support for <tt>__attribute__((noinline))</tt> in
- llvm-gcc, and added support for generic variable annotations which are
- propagated into the LLVM IR, e.g.
- "<tt>int X __attribute__((annotate("myproperty")));</tt>".</li>
-
-<li>Sheng Zhou and Christopher Lamb implemented alias analysis support for
-"restrict" pointer arguments to functions.</li>
-
-<li>Duncan contributed support for trampolines (taking the address of a nested
- function). Currently this is only supported on the X86 target.</li>
-
-<li>Lauro Ramos Venancio contributed support to encode alignment info in
- load and store instructions, the foundation for other alignment-related
- work.</li>
+<li>.</li>
</ul>
</div>
</p>
<ul>
-<li>Neil Booth contributed a new "APFloat" class, which ensures that floating
- point representation and constant folding is not dependent on the host
- architecture that builds the application. This support is the foundation
- for "long double" support that will be wrapped up in LLVM 2.2.</li>
-
-<li>Based on the APFloat class, Dale redesigned the internals of the ConstantFP
- class and has been working on extending the core and optimizer components to
- support various target-specific 'long double's. We expect this work to be
- completed in LLVM 2.2.</li>
-
-<li>LLVM now provides an LLVMBuilder class, which makes it significantly easier
- to create LLVM IR instructions.</li>
-
-<li>Reid contributed support for intrinsics that take arbitrary integer typed
- arguments. Dan Gohman and Chandler extended it to support arbitrary
- floating point arguments and vectors.</li>
+<li>Devang added LLVMFoldingBuilder.</li>
+<li>Dan added support for vector sin, cos, and pow intrinsics.</li>
</ul>
</div>
</p>
<ul>
-<li>Sterling Stein contributed a new BrainF frontend, located in llvm/examples.
- This shows a some of the more modern APIs for building a front-end, and
- demonstrates JIT compiler support.</li>
-
-<li>David Green contributed a new <tt>--enable-expensive-checks</tt> configure
- option which enables STL checking, and fixed several bugs exposed by
- it.</li>
+<li>.</li>
</ul>
</div>
<ul>
<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
(and probably other unix-like systems).</li>
-<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
+<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
64-bit modes.</li>
-<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
+<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
support is available for native builds with Visual C++).</li>
<li>Sun UltraSPARC workstations running Solaris 8.</li>
components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in a
- future release.</li>
-<li>The MSIL backend is experimental.</li>
-<li>The IA64 code generator is experimental.</li>
-<li>The Alpha backend is experimental.</li>
-<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
- <tt>-filetype</tt> llc option.</li>
+<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
+ LLVM 2.3.</li>
+<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
+<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
+ value for this option.</li>
+<li>The llvmc tool is not supported.</li>
</ul>
</div>
<div class="doc_text">
<ul>
-<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
-implement ordered FP comparisons</a>.</li>
<li>The Linux PPC32/ABI support needs testing for the interpreter and static
compilation, and lacks support for debug information.</li>
</ul>
<div class="doc_text">
-<p>llvm-gcc4 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
+<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>
</div>
<div class="doc_text">
<ul>
-<li><p>"long double" is silently transformed by the front-end into "double". There
-is no support for floating point data types of any size other than 32 and 64
-bits.</p></li>
-
<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
</li>
As in Algol and Pascal, lexical scoping of functions.
Nested functions are supported, but llvm-gcc does not support
- taking the address of a nested function (except on the X86 target)
+ taking the address of a nested function (except on the X86-32 target)
or non-local gotos.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Declaring that functions have no side effects or that they can never
return.<br>
- <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
- <tt>constructor</tt>, <tt>destructor</tt>,
+ <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
+ <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
<tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
- <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>, <tt>noreturn</tt>, <tt>regparm</tt>
+ <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
+ <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
<tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
<tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
- <b>Ignored:</b> <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
- <tt>malloc</tt>, <tt>no_instrument_function</tt></li>
+ <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
+ <tt>no_instrument_function</tt></li>
</ol>
</li>
itself, Qt, Mozilla, etc.</p>
<ul>
-<li>Exception handling only works well on the linux/x86-32 target.
-In some cases, illegally throwing an exception does not result
-in a call to terminate.</li>
-
-<!-- NO EH Support!
-
-<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
- performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
- function and in the <tt>setjmp</tt> receiver function may not be run.
- Objects in intervening stack frames will be destroyed, however (which is
- better than most compilers).</li>
-
-<li>The LLVM C++ front-end follows the <a
- href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
- This document, which is not Itanium specific, specifies a standard for name
- mangling, class layout, v-table layout, RTTI formats, and other C++
- representation issues. Because we use this API, code generated by the LLVM
- compilers should be binary compatible with machine code generated by other
- Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
- <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
- different from the model used in the Itanium ABI, so <b>exceptions will not
- interact correctly</b>. </li>
--->
+<li>Exception handling only works well on the X86 and PowerPC targets.</li>
</ul>
</div>
projects / oota-llvm.git / blobdiff