<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#subproj">Sub-project Status Update</a></li>
- <li><a href="#whatsnew">What's New in LLVM?</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="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>This document contains the release notes for the LLVM Compiler
Infrastructure, release 2.5. 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
+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
<!-- Unfinished features in 2.5:
Machine LICM
Machine Sinking
- LegalizeDAGTypes
- llc -enable-value-prop, propagation of value info (sign/zero ext info) from
- one MBB to another
+ 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?
+
+initial support for debug line numbers when optimization enabled, not useful in
+ 2.5 but will be for 2.6.
+
-->
<!-- for announcement email:
- mention dev mtg
- Xcode 3.1 and 3.1.1.
- -->
+ -->
<!-- *********************************************************************** -->
<div class="doc_section">
<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>.
+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>.
</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
+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 applications for X86-32 and X86-64,
-including the FreeBSD kernel. 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>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
+capable of successfully building many real-world applications for X86-32
+and X86-64,
+including the <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">FreeBSD
+kernel</a> and <a href="http://gcc.gnu.org/gcc-4.2/">gcc 4.2</a>. C++ is also
+making <a href="http://clang.llvm.org/cxx_status.html">incredible progress</a>,
+and work on templates has recently started. 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 mainlnie</a>
-and reporting any issues you hit to the <a
+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>
<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>
+ interface.</li>
+<li>The X86-64 ABI is now supported, including support for the Apple
+ 64-bit Objective-C runtime and zero cost exception handling.</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.</li>
+<li>Variable length arrays are now fully supported.</li>
+<li>C99 designated initializers are now fully supported.</li>
+<li>Clang now includes all major compiler headers, including a
+ redesigned <i>tgmath.h</i> and several more intrinsic headers.</li>
+<li>Many many bugs are fixed and many features have been added.</li>
+</ul>
</div>
<!--=========================================================================-->
<div class="doc_text">
-<p>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 bugs that occur on a specific path within a program. Examples
-of bugs the tool finds include logic errors such as null dereferences,
-violations of various API rules, dead code, and potential memory leaks in
-Objective-C programs. Since its inception, public feedback on the tool has been
-extremely positive, and conservative estimates put the number of real bugs it
-has found in industrial-quality software on the order of thousands.</p>
+<p>Previously announced in the last LLVM release, 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
+bugs that occur on a specific path within a program.</p>
-<p>The tool also provides a simple web GUI to inspect potential bugs found by
-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
-perform inline expansion of macros within the GUI itself.</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 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>
+<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>
</div>
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>Following LLVM 2.5, VMKit has its first release ? that you can find on its
+<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
bug fixes, cleanup and new features. The major changes are:</p>
<ul>
-<li>?</li>
+<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>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>
+
+<li>User-level management of thread stacks, so that thread local data access
+at runtime is fast and portable. </li>
+
+<li>Implementation of biased locking for faster object synchronizations at
+runtime.</li>
+
+<li>New support for OSX/X64, Linux/X64 (with the Boehm GC) and Linux/ppc32.</li>
</ul>
</div>
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="externalproj">External Projects Using LLVM 2.5</a>
+</div>
+<!-- *********************************************************************** -->
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="pure">Pure</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://pure-lang.googlecode.com/">Pure</a>
+is an algebraic/functional programming language based on term rewriting.
+Programs are collections of equations which are used to evaluate expressions in
+a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
+lexical closures, a hygienic macro system (also based on term rewriting),
+built-in list and matrix support (including list and matrix comprehensions) and
+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>
+</div>
+
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="ldc">LLVM D Compiler</a>
+</div>
+
+<div class="doc_text">
+<p>
+<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
+the D Programming Language using the LLVM optimizer and code generator.
+The LDC project works great with the LLVM 2.5 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.
+</p>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="RoadsendPHP">Roadsend PHP</a>
+</div>
+
+<div class="doc_text">
+<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?</a>
+ <a name="whatsnew">What's New in LLVM 2.5?</a>
</div>
<!-- *********************************************************************** -->
<p>LLVM 2.5 includes several major new capabilities:</p>
<ul>
-<li><p>?</p></li>
+<li>LLVM 2.5 includes a brand new <a
+href="http://en.wikipedia.org/wiki/XCore">XCore</a> backend.</li>
+
+<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>
+
+<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>
+
+<li>LLVM 2.5 no longer uses 'bison,' so it is easier to build on Windows.</li>
</ul>
</div>
includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
<ul>
-<li>?</li>
+<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>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="coreimprovements">LLVM Core Improvements</a>
+<a name="coreimprovements">LLVM IR and Core Improvements</a>
</div>
<div class="doc_text">
-<p>New features include:</p>
+<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>
<ul>
-<li>?</li>
-
+<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).
+The new <a href="LangRef.html#paramattrs">nocapture</a> attribute can be used
+on pointer arguments to indicate that the function does not return the pointer,
+store it in an object that outlives the call, or let the value of the pointer
+escape from the function in any other way.
+Note that it is the pointer itself that must not escape, not the value it
+points to: loading a value out of the pointer is perfectly fine.
+Many standard library functions (e.g. 'strlen', 'memcpy') have this property.
+<!-- 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>. 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>
+
</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 bug fixes and minor performance tweaks, this
release includes a few major enhancements and additions to the optimizers:</p>
<ul>
-<li>?</li>
+<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>The "-mem2reg" pass is now much faster on code with large basic blocks.</li>
+
+<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>
+
+<li>The "-scalarrepl" scalar replacement of aggregates pass is more aggressive
+ about promoting unions to registers.</li>
</ul>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="codegen">Code Generator Improvements</a>
+<a name="codegen">Target Independent Code Generator Improvements</a>
</div>
<div class="doc_text">
-<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>
+<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>
<ul>
-<li>?</li>
+<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 is 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
+the 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>
</ul>
+</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="x86">X86-32 and X86-64 Target Improvements</a>
</div>
+<div class="doc_text">
+<p>New features of the X86 target include:
+</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 and
+ auto-configures 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>
+</ul>
+
+</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="targetspecific">Target Specific Improvements</a>
+<a name="pic16">PIC16 Target Improvements</a>
</div>
<div class="doc_text">
-<p>New target-specific features include:
+<p>New features of the PIC16 target include:
</p>
<ul>
-<li>?</li>
+<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>The compiler can now emit libcalls for operations not supported by m/c
+instructions.</li>
+<li>Support for both data and ROM address spaces.</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="otherimprovements">Other Improvements</a>
+<a name="llvmc">Improvements in LLVMC</a>
</div>
<div class="doc_text">
-<p>New features include:
-</p>
+<p>New features include:</p>
<ul>
-<li>?</li>
+<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>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>
+
+<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>
+
+<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>
+
+<li>Hooks can now be provided with arguments. The syntax is "<tt>$CALL(MyHook,
+ 'Arg1', 'Arg2', 'Arg3')</tt>".</li>
+
+<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>
+
+<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>
+
+<li>Documentation now looks more consistent to the rest of the LLVM
+ docs. There is also a man page now.</li>
</ul>
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
<a name="changes">Major Changes and Removed Features</a>
<ul>
-<li>?</li>
+<li>llvm-gcc defaults to <tt>-fno-math-errno</tt> on all X86 targets.</li>
+
</ul>
API changes are:</p>
<ul>
-<li>?</li>
-</ul>
-
-<li>?</li>
+<li>Some deprecated interfaces to create <tt>Instruction</tt> subclasses, that
+ were spelled with lower case "create," have been removed.</li>
</ul>
</div>
<p>LLVM is known to work on the following platforms:</p>
<ul>
-<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
+<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
+<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
<div class="doc_text">
-<p>This section contains significant known problems with the LLVM system,
+<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>
<ul>
<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>
+<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
+ supported value for this option.</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 front-end supports variadic
+ <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
argument constructs on X86-64 by lowering them manually.</li>
</ul>
<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
<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 Itanium backend is highly experimental, and has a number of known
+<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>
inline assembly code</a>.</li>
<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
- C++ code compiled with llc or native compilers.</li>
+ C++ code compiled with <tt>llc</tt> or native compilers.</li>
<li>The C backend does not support all exception handling constructs.</li>
+<li>The C backend does not support arbitrary precision integers.</li>
</ul>
</div>
<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>
<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>
<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).</li>
-<li>Some gcc specific Ada tests continue to crash the compiler.</li>
+(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)
<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>
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