<li><a href="#whatsnew">What's New in LLVM?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#portability">Portability and Supported Platforms</a></li>
- <li><a href="#knownproblems">Known Problems</a>
+ <li><a href="#knownproblems">Known Problems</a></li>
<li><a href="#additionalinfo">Additional Information</a></li>
</ol>
<div class="doc_author">
- <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
+ <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
</div>
<!-- *********************************************************************** -->
<p>Note that if you are reading this file from a Subversion checkout or the
main LLVM web page, this document applies to the <i>next</i> release, not the
-current one. To see the release notes for a specific releases, please see the
+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>
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 <a href="#vmkit">VMKit Project</a>.
</p>
</div>
yet production quality, it is progressing very nicely. In addition, C++
front-end work has started to make significant progress.</p>
-<p>Codegen progress/state [DANIEL]</p>
+<p>Clang, in conjunction with the <tt>ccc</tt> driver, is now usable as a
+replacement for gcc for building some small- to medium-sized C applications.
+Additionally, Clang now has code generation support for Objective-C on Mac OS X
+platform. Major highlights include:</p>
+
+<ul>
+ <li> Clang/ccc pass almost all of the LLVM test suite on Mac OS X and Linux
+on the 32-bit x86 architecture. This includes significant C
+applications such as <a href="http://www.sqlite.org">sqlite3</a>,
+<a href="http://www.lua.org">lua</a>, and
+<a href="http://www.clamav.net">Clam AntiVirus</a>. </li>
+
+ <li> Clang can build the majority of Objective-C examples shipped with the
+Mac OS X Developer Tools. </li>
+</ul>
+
+<p>Clang code generation still needs considerable testing and development,
+however. Some areas under active development include:</p>
+
+<ul>
+ <li> Improved support for C and Objective-C features, for example
+ variable-length arrays, va_arg, exception handling (Obj-C), and garbage
+ collection (Obj-C). </li>
+ <li> ABI compatibility, especially for platforms other than 32-bit
+ x86. </li>
+</ul>
</div>
the tool. While still early in development, the GUI illustrates some of the key
features of Clang: accurate source location information, which is used by the
GUI to highlight specific code expressions that relate to a bug (including those
-that span multiple lines) and built-in knowledge of macros, which is used to
+that span multiple lines); and built-in knowledge of macros, which is used to
perform inline expansion of macros within the GUI itself.</p>
<p>The set of checks performed by the static analyzer is gradually expanding,
-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>
+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>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="vmkit">vmkit: JVM/CLI Virtual Machine Implementation</a>
+<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
</div>
<div class="doc_text">
<p>
-The <a href="http://vmkit.llvm.org/">vmkit project</a> is an implementation of
+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>
-<p>[NICOLAS]</p>
+<p>Following LLVM 2.4, VMKit has its first release 0.24 that you can find on its
+<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
+bug fixes, cleanup and new features. The major changes are:</p>
+
+<ul>
+<li> Support for generics in the .Net virtual machine.</li>
+<li> Initial support for the Mono class libraries. </li>
+<li> Support for MacOSX/x86, following LLVM's support for exceptions in
+JIT on MacOSX/x86. </li>
+<li> A new vmkit driver: a program to run java or .net applications. The driver
+supports llvm command line arguments including the new "-fast" option. </li>
+<li> A new memory allocation scheme in the JVM that makes unloading a
+class loader very fast. </li>
+<li> VMKit now follows the LLVM Makefile machinery. </li>
+
+</ul>
</div>
<div class="doc_text">
-<p>This release includes a huge number of bug fixes, performance tweaks and
+<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>
<ul>
<li><p>The most visible end-user change in LLVM 2.4 is that it includes many
optimizations and changes to make -O0 compile times much faster. You should see
-improvements on the order of 30% or more faster than LLVM 2.3. There are many
-pieces to this change, described in more detail below. The speedups and new
-components can also be used for JIT compilers that want fast compilation as
-well.</p></li>
+improvements in speed on the order of 30% (or more) than in LLVM 2.3. There are
+many pieces to this change described in more detail below. The speedups and new
+components can also be used for JIT compilers that want fast
+compilation.</p></li>
<li><p>The biggest change to the LLVM IR is that Multiple Return Values (which
were introduced in LLVM 2.3) have been generalized to full support for "First
Class Aggregate" values in LLVM 2.4. This means that LLVM IR supports using
structs and arrays as values in a function. This capability is mostly useful
for front-end authors, who prefer to treat things like complex numbers, simple
-tuples, dope vectors, etc as Value*'s instead of as a tuple of Value*'s or as
-memory values.</p></li>
+tuples, dope vectors, etc., as Value*'s instead of as a tuple of Value*'s or as
+memory values. Bitcode files from LLVM 2.3 will automatically migrate to the
+general representation.</p></li>
<li><p>LLVM 2.4 also includes an initial port for the PIC16 microprocessor. This
-is the LLVM targer that only has support for 8 bit registers, and a number of
-other crazy constraints. While the port is still in early development stages,
-it shows some interesting things you can do with LLVM.</p></li>
+target only has support for 8 bit registers, and a number of other crazy
+constraints. While the port is still in early development stages, it shows some
+interesting things you can do with LLVM.</p></li>
</ul>
<ul>
<li>LLVM 2.4 supports the full set of atomic <tt>__sync_*</tt> builtins. LLVM
-2.3 only supported those used by OpenMP, but 2.4 supports them all. While
-llvm-gcc supports all of these builtins, note that not all targets do. X86
-support them all in both 32-bit and 64-bit mode and PowerPC supports them all
-except for the 64-bit operations when in 32-bit mode.</li>
+2.3 only supported those used by OpenMP, but 2.4 supports them all. Note that
+while llvm-gcc supports all of these builtins, not all targets do. X86 support
+them all in both 32-bit and 64-bit mode and PowerPC supports them all except for
+the 64-bit operations when in 32-bit mode.</li>
<li>llvm-gcc now supports an <tt>-flimited-precision</tt> option, which tells
-the compiler that it is ok to use low-precision approximations of certain libm
-functions (like tan, log, etc). This allows you to get high performance if you
-only need (say) 14-bits of precision.</li>
+the compiler that it is okay to use low-precision approximations of certain libm
+functions (like <tt>exp</tt>, <tt>log</tt>, etc). This allows you to get high
+performance if you only need (say) 12-bits of precision.</li>
<li>llvm-gcc now supports a C language extension known as "<a
-href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks
-</a>. This feature is similar to nested functions and closures, but does not
-require stack trampolines (with most ABIs) and supports returning closures
+href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks</a>".
+This feature is similar to nested functions and closures, but does not
+require stack trampolines (with most ABIs), and supports returning closures
from functions that define them. Note that actually <em>using</em> Blocks
requires a small runtime that is not included with llvm-gcc.</li>
</div>
<div class="doc_text">
-<p>New features include:
-</p>
+<p>New features include:</p>
<ul>
-<li>A major change to the "Use" class landed, which shrank it by 25%. Since
+<li>A major change to the <tt>Use</tt> class landed, which shrank it by 25%. Since
this is a pervasive part of the LLVM, it ended up reducing the memory use of
LLVM IR in general by 15% for most programs.</li>
</li>
<li>LLVM 2.4 includes some changes for better vector support. First, the shift
-operations (<tt>shl</tt>, <tt>ashr</tt>, <tt>lshr</tt>) now all support vectors
-and do an element-by-element shift (shifts of the whole vector can be
-accomplished by bitcasting the vector to <1 x i128> for example). Second,
-there is initial support in development for vector comparisons with the
-<a href="LangRef.html#i_fcmp">fcmp</a>/<a href="LangRef.html#i_icmp">icmp</a>
+operations (<tt>shl</tt>, <tt>ashr</tt>, and <tt>lshr</tt>) now all support
+vectors and do an element-by-element shift (shifts of the whole vector can be
+accomplished by bitcasting the vector to <tt><1 x i128></tt>, for example). Second,
+there is initial support in development for vector comparisons with the
+<tt><a href="LangRef.html#i_fcmp">fcmp</a>/<a href="LangRef.html#i_icmp">icmp</a></tt>
instructions. These instructions compare two vectors and return a vector of
-i1's for each result. Note that there is very little codegen support available
-for any of these IR features though.</li>
+<tt>i1</tt>'s for each result. Note that there is very little codegen support
+available for any of these IR features though.</li>
<li>A new <tt>DebugInfoBuilder</tt> class is available, which makes it much
easier for front-ends to create debug info descriptors, similar to the way that
-IRBuilder makes it easier to create LLVM IR.</li>
+<tt>IRBuilder</tt> makes it easier to create LLVM IR.</li>
+
+<li>The <tt>IRBuilder</tt> class is now parameterized by a class responsible
+for constant folding. The default <tt>ConstantFolder</tt> class does target independent
+constant folding. The <tt>NoFolder</tt> class does no constant folding at all, which is
+useful when learning how LLVM works. The <tt>TargetFolder</tt> class folds the most,
+doing target dependent constant folding.</li>
-<li>LLVM now supports "function attributes", which allows us to seperate return
+<li>LLVM now supports "function attributes", which allow us to separate return
value attributes from function attributes. LLVM now supports attributes on a
function itself, a return value, and its parameters. New supported function
-attributes include noinline/alwaysinline and the "opt-size" flag which says the
-function should be optimized for code size.</li>
+attributes include <tt>noinline/alwaysinline</tt> and the <tt>opt-size</tt> flag,
+which says the function should be optimized for code size.</li>
<li>LLVM IR now directly represents "common" linkage, instead of
representing it as a form of weak linkage.</li>
<li>LLVM 2.4 includes a new loop deletion pass (which removes output-free
provably-finite loops) and a rewritten Aggressive Dead Code Elimination (ADCE)
pass that no longer uses control dependence information. These changes speed up
-the optimizer and also prevents it from deleting output-free infinite
+the optimizer and also prevent it from deleting output-free infinite
loops.</li>
<li>The new AddReadAttrs pass works out which functions are read-only or
-read-none (these correspond to 'pure' and 'const' in C) and marks them
+read-none (these correspond to 'pure' and 'const' in GCC) and marks them
with the appropriate attribute.</li>
<li>LLVM 2.4 now includes a new SparsePropagation framework, which makes it
<div class="doc_text">
-<p>We put a significant amount of work into the code generator infrastructure,
+<p>We have put a significant amount of work into the code generator infrastructure,
which allows us to implement more aggressive algorithms and make it run
faster:</p>
<li>In addition to the new 'fast' instruction selection path, many existing
pieces of the code generator have been optimized in significant ways.
SelectionDAG's are now pool allocated and use better algorithms in many
- places, the ".s" file printers now use raw_ostream to emit text much faster,
+ places, the ".s" file printers now use <tt>raw_ostream</tt> to emit text much faster,
etc. The end result of these improvements is that the compiler also takes
substantially less time to generate code that is just as good (and often
better) than before.</li>
-<li>Each target has been split to separate the .s file printing logic from the
+<li>Each target has been split to separate the ".s" file printing logic from the
rest of the target. This enables JIT compilers that don't link in the
- (somewhat large) code and data tables used for printing a .s file.</li>
+ (somewhat large) code and data tables used for printing a ".s" file.</li>
<li>The code generator now includes a "stack slot coloring" pass, which packs
together individual spilled values into common stack slots. This reduces
<ul>
<li>Exception handling is supported by default on Linux/x86-64.</li>
<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li>
-<li>@llvm.frameaddress now supports getting the frame address of stack frames
+<li><tt>@llvm.frameaddress</tt> now supports getting the frame address of stack frames
> 0 on x86/x86-64.</li>
-<li>MIPS floating point support? [BRUNO]</li>
+<li>MIPS has improved a lot since last release, the most important changes
+ are: Little endian support, floating point support, allegrex core and
+ intrinsics support. O32 ABI is improved but isn't complete. The EABI
+ was implemented and is fully supported. We also have support for small
+ sections and gp_rel relocation for its access, a threshold in bytes can be
+ specified through command line.</li>
<li>The PowerPC backend now supports trampolines.</li>
</ul>
build your own tools based on it.</li>
<li>LLVM 2.4 includes a number of new generic algorithms and data structures,
- include a scoped hash table, 'immutable' data structures, and a
- <tt>raw_ostream</tt> class. The <tt>raw_ostream</tt> class and
+ including a scoped hash table, 'immutable' data structures, a simple
+ free-list manager, and a <tt>raw_ostream</tt> class.
+ The <tt>raw_ostream</tt> class and
<tt>format</tt> allow for efficient file output, and various pieces of LLVM
have switched over to use it. The eventual goal is to eliminate
- std::ostream in favor of it.</li>
+ use of <tt>std::ostream</tt> in favor of it.</li>
+
+<li>LLVM 2.4 includes an optional build system based on CMake. It
+ still is in its early stages but can be useful for Visual C++
+ users who can not use the Visual Studio IDE.</li>
-<li>Recycler + pool allocation stuff? [DAN]</li>
</ul>
</div>
<ul>
-<li>Attributes changes [DEVANG] </li>
+<li>Now, function attributes and return value attributes are managed
+separately. Interface exported by <tt>ParameterAttributes.h</tt> header is now
+exported by <tt>Attributes.h</tt> header. The new attributes interface changes are:
+<ul>
+<li><tt>getParamAttrs</tt> method is now replaced by
+<tt>getParamAttributes</tt>, <tt>getRetAttributes</tt> and
+<tt>getFnAttributes</tt> methods.</li>
+<li> Return value attributes are stored at index 0. Function attributes are
+stored at index ~0U. Parameter attributes are stored at index that matches
+parameter number.</li>
+<li> <tt>ParamAttr</tt> namespace is now renamed as <tt>Attribute</tt>.</li>
+<li> The name of the class that manages reference count of opaque
+attributes is changed from <tt>PAListPtr</tt> to <tt>AttrListPtr</tt>.</li>
+<li> <tt>ParamAttrsWithIndex</tt> is now renamed as <tt>AttributeWithIndex</tt>.
+</li>
+</ul>
+</li>
<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
-"llvm/Analysis/ValueTracking.h".</li>
+"<tt>llvm/Analysis/ValueTracking.h</tt>".</li>
<li>The APIs to create various instructions have changed from lower case
"create" methods to upper case "Create" methods (e.g.
<tt>BinaryOperator::create</tt>). LLVM 2.4 includes both cases, but the
- lower case ones are removed in mainline, please migrate.</li>
-
-<li>Various header files like "llvm/ADT/iterator" were given a .h suffix.
- Change your code to #include "llvm/ADT/iterator.h" instead.</li>
-
+ lower case ones are removed in mainline (2.5 and later), please migrate.</li>
+
+<li>Various header files like "<tt>llvm/ADT/iterator</tt>" were given a ".h" suffix.
+ Change your code to #include "<tt>llvm/ADT/iterator.h</tt>" instead.</li>
+
+<li>The <tt>getresult</tt> instruction has been removed and replaced with the
+ <tt>extractvalue</tt> instruction. This is part of support for first class
+ aggregates.</li>
+
+<li>In the code generator, many <tt>MachineOperand</tt> predicates were renamed to be
+ shorter (e.g. <tt>isFrameIndex()</tt> -> <tt>isFI()</tt>),
+ <tt>SDOperand</tt> was renamed to <tt>SDValue</tt> (and the "<tt>Val</tt>"
+ member was changed to be the <tt>getNode()</tt> accessor), and the
+ <tt>MVT::ValueType</tt> enum has been replaced with an "<tt>MVT</tt>"
+ struct. The <tt>getSignExtended</tt> and <tt>getValue</tt> methods in the
+ ConstantSDNode class were renamed to <tt>getSExtValue</tt> and
+ <tt>getZExtValue</tt> respectively, to be more consistent with
+ the <tt>ConstantInt</tt> class.</li>
</ul>
</div>
<p>LLVM is known to work on the following platforms:</p>
<ul>
-<li>Intel and AMD machines (IA32) 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 10.3 and above in 32-bit and
- 64-bit modes.</li>
+<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>
+<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 with the Cygwin libraries (limited
support is available for native builds with Visual C++).</li>
<div class="doc_text">
-<p>This section contains all known problems with the LLVM system, listed by
-component. As new problems are discovered, they will be added to these
-sections. If you run into a problem, please check the <a
+<p>This section contains significant known problems with the LLVM system,
+listed by component. If you run into a problem, please check the <a
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</p>
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
+<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
value for this option.</li>
</ul>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="mips-be">Known problems with the MIPS back-end</a>
+</div>
+
+<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>
+
+</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="alpha-be">Known problems with the Alpha back-end</a>
<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>
+ are interested, please contact the LLVMdev mailing list.</li>
</ul>
</div>
<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>
+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
<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>
+ 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>
+
+<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>
+</ul>
+</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<hr>
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