<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.0 Release Notes</title>
+ <title>LLVM 2.3 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.0 Release Notes</div>
+<div class="doc_title">LLVM 2.3 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 LLVM 2.3 (currently in
+progress on SVN HEAD)</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 2.0. Here we describe the status of LLVM, including any
-known problems and major improvements from the previous release. All LLVM
+infrastructure, release 2.3. 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>.
+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
href="http://mail.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 CVS 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 the current or previous releases, see the <a
-href="http://llvm.org/releases/">releases page</a>.</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 releases, please see the
+<a href="http://llvm.org/releases/">releases page</a>.</p>
</div>
<div class="doc_text">
-<p>This is the eleventh public release of the LLVM Compiler Infrastructure.
-Being the first major release since 1.0, this release is different in several
-ways from our previous releases:</p>
-
-<ol>
-<li>We took this as an opportunity to
-break backwards compatibility with the LLVM 1.x bytecode and .ll file format.
-If you have LLVM 1.9 .ll files that you would like to upgrade to LLVM 2.x, we
-recommend the use of the stand alone <a href="#llvm-upgrade">llvm-upgrade</a>
-tool (which is included with 2.0). We intend to keep compatibility with .ll
-and .bc formats within the 2.x release series, like we did within the 1.x
-series.</li>
-<li>There are several significant change to the LLVM IR and internal APIs, such
- as a major overhaul of the type system, the completely new bitcode file
- format, etc.</li>
-<li>We designed the release around a 6 month release cycle instead of the usual
- 3-month cycle. This gave us extra time to develop and test some of the
- more invasive features in this release.</li>
-<li>LLVM 2.0 no longer supports the llvm-gcc3 front-end.</li>
-</ol>
-
-<p>Note that while this is a major version bump, this release has been
- extensively tested on a wide range of software. It is easy to say that this
- is our best release yet, in terms of both features and correctness.</p>
+<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
+It includes many features and refinements from LLVM 2.2.</p>
</div>
+<!-- Unfinished features in 2.3:
+ Index Set Splitting not enabled by default
+ Machine LICM
+ Machine Sinking
+ LegalizeDAGTypes
+ -->
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="newfeatures">New Features in LLVM 2.0</a>
+<a name="deprecation">Removed features in LLVM 2.3</a>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="majorchanges">Major Changes</a></div>
<div class="doc_text">
-<p>blah
-</p>
-
-<ul>
-
-<li>llvm-gcc3 is now officially unsupported. Users are required to
- upgrade to llvm-gcc4. llvm-gcc4 includes many features over
- llvm-gcc3, is faster, and is much easier to build.</li>
-
-<li>Integer types are now completely signless. This means that we
- have types like i8/i16/i32 instead of ubyte/sbyte/short/ushort/int
- etc. LLVM operations that depend on sign have been split up into
- separate instructions (<a href="http://llvm.org/PR950">PR950</a>).</li>
-
-<li>Arbitrary bitwidth integers (e.g. i13, i36, i42, etc) are now
- supported in the LLVM IR and optimizations. However, neither llvm-gcc nor
- the native code generators support non-standard width integers
- (<a href="http://llvm.org/PR1043">PR1043</a>).</li>
-
-<li>'type planes' have been removed (<a href="http://llvm.org/PR411">PR411</a>).
- It is no longer possible to have two values with the same name in the
- same symbol table. This simplifies LLVM internals, allowing significant
- speedups.</li>
-
-<li>Global variables and functions in .ll files are now prefixed with
- @ instead of % (<a href="http://llvm.org/PR645">PR645</a>).</li>
-
-<li>The LLVM 1.x "bytecode" format has been replaced with a
- completely new binary representation, named 'bitcode'. Because we
- plan to maintain binary compatibility between LLVM 2.x ".bc" files,
- this is an important change to get right. Bitcode brings a number of
- advantages to the LLVM over the old bytecode format. It is denser
- (files are smaller), more extensible, requires less memory to read,
- is easier to keep backwards compatible (so LLVM 2.5 will read 2.0 .bc
- files), and has many other nice features.</li>
-
-<li>Support was added for alignment values on load and store
- instructions (<a href="http://www.llvm.org/PR400">PR400</a>). This
- allows the IR to express loads that are not
- sufficiently aligned (e.g. due to pragma packed) or to capture extra
- alignment information. </li>
-
-<li>LLVM now has a new MSIL backend. llc - march=msil will now turn LLVM
- into MSIL (".net") bytecode. This is still fairly early development
- with a number of limitations.</li>
-
-<li>Support has been added for 'protected visibility' in ELF.</li>
-
-<li>Thread Local Storage with the __thread keyword was implemented along
- with added codegen support for Linux on X86 and ARM.</li>
-<li>ELF symbol aliases supported has been added.</li>
+<p>LLVM 2.2 was the last LLVM release to support llvm-gcc 4.0 and llvm-upgrade.
+llvm-gcc 4.0 has been replaced with llvm-gcc 4.2. llvm-upgrade was useful for
+upgrading llvm 1.9 files to llvm 2.x syntax, but you can always use a previous
+llvm release to do this.</p>
-<li>Added support for 'polymorphic intrinsics', allowing things like
- llvm.ctpop to work on arbitrary width integers.</li>
-
-</ul>
-
</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="frontends">llvm-gcc 4.2 and clang</a>
+</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="llvmgccfeatures">llvm-gcc
-Improvements</a></div>
<div class="doc_text">
-<p>New features include:
-</p>
-
-<ul>
-<li>Precompiled Headers (PCH) support has been implemented.</li>
-<li>Support for external weak linkage and hidden visibility has been added.</li>
+<p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end. </p>
-<li>Packed structure types are now supported , which allows LLVM to express
- unaligned data more naturally.</li>
+<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 2.3 release. If you are interested in
+this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
-<li>Inline assembly support has been improved and many bugs were fixed.
- The two large missing features are support for 80-bit floating point stack
- registers on X86 (<a href="http://llvm.org/PR879">PR879</a>), and support for inline asm in the C backend (<a href="http://llvm.org/PR802">PR802</a>).</li>
+</div>
-<li>Ada support, such as nested functions, has been improved.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="majorfeatures">Major New Features</a>
+</div>
-<li>Tracking function parameter/result attributes is now possible.</li>
+<div class="doc_text">
-<li>Its is now easier to configure llvm-gcc for linux.</li>
+<p>LLVM 2.3 includes several major new capabilities:</p>
-<li>Many enhancements have been added, such as improvements to NON_LVALUE_EXPR,
- arrays with non-zero base, structs with variable sized fields,
- VIEW_CONVERT_EXPR, CEIL_DIV_EXPR, and many other things.</li>
+<ul>
+</ul>
-<li>Improved "attribute packed" support in the CFE, and handle many
- other obscure struct layout cases correctly.</li>
+</div>
-</ul>
-
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="coreimprovements">LLVM Core Improvements</a>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="optimizer">Optimizer
-Improvements</a></div>
<div class="doc_text">
<p>New features include:
</p>
<ul>
-<li>The pass manager has been entirely rewritten, making it significantly
- smaller, simpler, and more extensible. Support has been added to run
- FunctionPasses interlaced with CallGraphSCCPasses.</li>
-
-<li>The -scalarrepl pass can now promote unions containing FP values into
- a register, it can also handle unions of vectors of the same size.</li>
-
-<li>The predicate simplifier pass has been improved, making it able to do
- simple value range propagation and eliminate more conditionals.</li>
-
-<li>There is a new new LoopPass class. The passmanager has been
- modified to support it, and all existing loop xforms have been
- converted to use it. </li>
-
-<li>There is a new loop rotation pass, which converts "for loops" into
- "do/while loops", where the condition is at the bottom of the loop.</li>
-
-<li>ModulePasses may now use the result of FunctionPasses.</li>
-
-<li>The [Post]DominatorSet classes have been removed from LLVM and clients switched to use the far-more-efficient ETForest class instead. </li>
-
-<li>The ImmediateDominator class has also been removed, and clients have been switched to use DominatorTree instead.</li>
</ul>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="codegen">Code
-Generator Enhancements</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="codegen">Code Generator Improvements</a>
+</div>
<div class="doc_text">
-<p>
-New features include:
-</p>
-
-<ul>
-<li>Support for Zero-cost DWARF exception handling has been added. It is mostly
- complete and just in need of continued bug fixes and optimizations at
- this point.</li>
-
-<li>Progress has been made on a direct Mach-o .o file writer. Many small
- apps work, but it is not quite complete yet.</li>
-
-<li>Support was added for software floating point routines.</li>
-
-<li>DWARF debug information generation has been improved. LLVM now passes
- most of the GDB testsuite on MacOS and debug info is more dense.</li>
-<li>A new register scavenger has been implemented, which is useful for
- finding free registers after register allocation. This is useful when
- rewriting frame references on RISC targets, for example.</li>
+<p>We 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>Heuristics have been added to avoid coalescing vregs with very large live
- ranges to physregs.</li>
-
-<li>Support now exists for very simple (but still very useful)
- rematerialization the register allocator, enough to move
- instructions like "load immediate" and constant pool loads.</li>
-
-<li>Significantly improved 'switch' lowering, improving codegen for
- sparse switches that have dense subregions, and implemented support
- for the shift/and trick.</li>
-
-<li>The code generator now has more accurate and general hooks for
- describing addressing modes ("isLegalAddressingMode") to
- optimizations like loop strength reduction and code sinking.</li>
-
-<li>The Loop Strength Reduction pass has been improved, and support added
- for sinking expressions across blocks to reduce register pressure.</li>
-
-<li>Added support for tracking physreg sub-registers and super-registers
- in the code generator, as well as extensive register
- allocator changes to track them.</li>
-
-<li>There is initial support for virtreg sub-registers
- (<a href="http://llvm.org/PR1350">PR1350</a>).</li>
-
-</ul>
-
-<p>In addition, the LLVM target description format has itself been extended in
- several ways:</p>
-
<ul>
-<li>Extended TargetData to support better target parameterization in
- the .ll/.bc files, eliminating the 'pointersize/endianness' attributes
- in the files (<a href="http://llvm.org/PR761">PR761</a>).</li>
-
-<li>TargetData was generalized for finer grained alignment handling,
- handling of vector alignment, and handling of preferred alignment</li>
-
-<li>LLVM now supports describing target calling conventions
- explicitly in .td files, reducing the amount of C++ code that needs
- to be written for a port.</li>
-
+<li>MemOperand in the code generator.</li>
</ul>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="specifictargets">Target-Specific
-Improvements</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="optimizer">Optimizer Improvements</a>
+</div>
<div class="doc_text">
-<p>X86-Specific Code Generator Enhancements:
-</p>
+<p>In addition to a huge array of bug fixes and minor performance tweaks, the
+LLVM 2.3 optimizers support a few major enhancements:</p>
<ul>
-<li>The scheduler was improved to better reduce register pressure on
- X86 and other targets that are register pressure sensitive</li>
-<li>Linux/x86-64 support has been improved.</li>
-<li>PIC support for linux/x86 has been added.</li>
-<li>Support now exists for the GCC regparm attribute, and code in the X86
- backend to respect it.</li>
-<li>Various improvements have been made for the X86-64 JIT, allowing it to
- generate code in the large code model</li>
-<li>LLVM now supports inline asm with multiple constraint letters per operand
- (like "ri") which is common in X86 inline asms.</li>
-<li>Early support has been added for X86 inline asm in the C backend.</li>
-<li>Added support for the X86 MMX instruction set.</li>
-
-</ul>
-<p>ARM-Specific Code Generator Enhancements:
-</p>
+<li>Index set splitting on by default.</li>
-<ul>
-<li>Several improvements have been made to the ARM backend, including basic
- inline asm support, weak linkage support, static ctor/dtor support and
- many bug fixes.</li>
-<li>There are major enhancements to the ARM backend, including support for ARM
- v4-v6, vfp support, soft float, pre/postinc support, load/store multiple
- generation, constant pool entry motion (to support large functions),
- and enhancements to ARM constant island pass.
- </li>
-<li>Added support for Thumb code generation (an ARM subtarget).</li>
-<li>More aggressive size analysis for ARM inline asm strings was
- implemented.</li>
</ul>
</div>
-<p>Other Target-Specific Code Generator Enhancements:
-</p>
-
-<ul>
-<li>The PowerPC 64 JIT now supports addressing code loaded above the 2G
- boundary.</li>
-
-<li>Improved support for the Linux/ppc ABI and the linux/ppc JIT is fully
- functional now. llvm-gcc and static compilation are not fully supported
- yet though.</li>
-
-<li>Many bugs fixed for PowerPC 64.</li>
-
-<li>Support was added for the ARM AAPCS and EABI ABIs and PIC codegen on
- arm/linux.</li>
-
-<li>Several bugs in DWARF debug emission on linux and cygwin/mingw were fixed.
- Debugging basically works on these targets now.</li>
-
-<li>Support has been added for the X86-64 large code model to the JIT,
- which is useful if JIT'd function bodies are more than 2G away from
- library functions.</li>
-
-<li>Several bugs were fixed for DWARF debug info generation on arm/linux.</li>
-
-</ul>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="targetspecific">Target Specific Improvements</a>
</div>
-
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
<div class="doc_text">
-
-<p>This release includes many other improvements, including
-performance work, specifically designed to tune datastructure
-usage. This makes several critical components faster.</p>
-
-<p>More specific changes include:</p>
+<p>New target-specific features include:
+</p>
<ul>
-<li>LLVM no longer relies on static destructors to shut itself down. Instead,
- it lazily initializes itself and shuts down when llvm_shutdown() is
- explicitly called.</li>
-
-<li>LLVM now has significantly fewer static constructors, reducing startup time.
- </li>
-
-<li>Several classes have been refactored to reduce the amount of code that
- gets linked into apps that use the JIT.</li>
-
-<li>Construction of intrinsic function declarations has been simplified.</li>
-
-<li>The llvm-upgrade tool now exists. This migrates LLVM 1.9 .ll files to
- LLVM 2.0 syntax.</li>
-
-<li>The gccas/gccld tools have been removed.</li>
-
-<li>Support has been added to llvm-test for running on low-memory
- or slow machines (make SMALL_PROBLEM_SIZE=1).</li>
-
-<li>llvm-test is now more portable and should build with MS Visual Studio.</li>
-
</ul>
+
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="apichanges">API Changes</a></div>
-<div class="doc_text">
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="otherimprovements">Other Improvements</a>
+</div>
-<p>LLVM 2.0 contains a revamp of the type system and several other significant
-internal changes. If you are programming to the C++ API, be aware of the
-following major changes:</p>
+<div class="doc_text">
+<p>New features include:
+</p>
<ul>
-<li>Pass registration is slightly different in LLVM 2.0 (you now needs an
- intptr_t in your constructor), as explained in the <a
- href="WritingAnLLVMPass.html#basiccode">Writing an LLVM Pass</a>
- document.</li>
-
-<li><tt>ConstantBool</tt>, <tt>ConstantIntegral</tt> and <tt>ConstantInt</tt>
- classes have been merged together, we now just have
- <tt>ConstantInt</tt>.</li>
-
-<li><tt>Type::IntTy</tt>, <tt>Type::UIntTy</tt>, <tt>Type::SByteTy</tt>, ... are
- replaced by <tt>Type::Int8Ty</tt>, <tt>Type::Int16Ty</tt>, etc. LLVM types
- have always corresponded to fixed size types
- (e.g. long was always 64-bits), but the type system no longer includes
- information about the sign of the type.</li>
-
-<li>Several classes (<tt>CallInst</tt>, <tt>GetElementPtrInst</tt>,
- <tt>ConstantArray</tt>, etc), that once took <tt>std::vector</tt> as
- arguments now take ranges instead. For example, you can create a
- <tt>GetElementPtrInst</tt> with code like:
-
- <pre>
- Value *Ops[] = { Op1, Op2, Op3 };
- GEP = new GetElementPtrInst(BasePtr, Ops, 3);
- </pre>
-
- This avoids creation of a temporary vector (and a call to malloc/free). If
- you have an std::vector, use code like this:
- <pre>
- std::vector<Value*> Ops = ...;
- GEP = new GetElementPtrInst(BasePtr, &Ops[0], Ops.size());
- </pre>
-
- </li>
-
-<li>CastInst is now abstract and its functionality is split into several parts,
- one for each of the <a href="LangRef.html#convertops">new cast
- instructions</a>.</li>
-
-<li><tt>Instruction::getNext()/getPrev()</tt> are now private (along with
- <tt>BasicBlock::getNext</tt>, etc), for efficiency reasons (they are now no
- longer just simple pointers). Please use BasicBlock::iterator, etc instead.
-</li>
-
-<li><tt>Module::getNamedFunction()</tt> is now called
- <tt>Module::getFunction()</tt>.</li>
-
-<li><tt>SymbolTable.h</tt> has been split into <tt>ValueSymbolTable.h</tt> and
-<tt>TypeSymbolTable.h</tt>.</li>
</ul>
+
</div>
-
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="portability">Portability and Supported Platforms</a>
<p>LLVM is known to work on the following platforms:</p>
<ul>
- <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
+<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
(and probably other unix-like systems).</li>
-<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
-<li>Sun UltraSPARC workstations running Solaris 8.</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>
-<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
- 64-bit modes.</li>
+<li>Sun UltraSPARC workstations running Solaris 8.</li>
<li>Alpha-based machines running Debian GNU/Linux.</li>
<li>Itanium-based machines running Linux and HP-UX.</li>
</ul>
be broken or unreliable, or are in early development. These components should
not be relied on, and bugs should not be filed against them, but they may be
useful to some people. In particular, if you would like to work on one of these
-components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
+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 in a
- future release.</li>
-<li>C++ EH support</li>
-<li>The IA64 code generator is experimental.</li>
-<li>The Alpha JIT 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 MSIL, IA64, Alpha, SPU, 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>
<ul>
<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
assembly that uses the X86 floating point stack</a>.</li>
+<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
+ problems</a> on operating systems that don't require 16-byte stack alignment
+ (including most non-darwin OS's like linux).</li>
+<li>The X86 backend generates inefficient floating point code when configured to
+ generate code for systems that don't have SSE2.</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 Dwarf debugging informations.
+compilation, and lacks support for debug information.</li>
</ul>
</div>
<div class="doc_text">
<ul>
-<li>The Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
-processors, any thumb program compiled with LLVM crashes or produces wrong
-results. (<a href="http://llvm.org/PR1388">PR1388</a>)</li>
+<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
+processors, thumb programs can crash or produce wrong
+results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
</li>
-<li>QEMU-ARM (<= 0.9.0) wrongly executes programs compiled with LLVM. A non-affected QEMU version must be used or this
-<a href="http://cvs.savannah.nongnu.org/viewcvs/qemu/target-arm/translate.c?root=qemu&r1=1.46&r2=1.47&makepatch=1&diff_format=h">
-patch</a> must be applied on QEMU.</li>
+<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
+programs compiled with LLVM. Please use more recent versions of QEMU.</li>
</ul>
</div>
<ul>
<li><a href="http://llvm.org/PR802">The C backend does not support inline
assembly code</a>.</li>
+<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
+ yet</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>
+<li>The C backend does not support all exception handling constructs.</li>
</ul>
</div>
<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>
-<p>FIXME: the list of supported stuff below needs to be updated. We do support
-tls now, what else??</p>
</div>
<!-- _______________________________________________________________________ -->
</div>
<div class="doc_text">
-
<ul>
-<li>"long double" is 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.</li>
-
-<li>Although many GCC extensions are supported, some are not. In particular,
- the following extensions are known to <b>not be</b> supported:
- <ol>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
- </ol>
-
- <p>The following GCC extensions are <b>partially</b> supported. An ignored
- attribute means that the LLVM compiler ignores the presence of the attribute,
- but the code should still work. An unsupported attribute is one which is
- ignored by the LLVM compiler and will cause a different interpretation of
- the program.</p>
+<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>
+<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
<ol>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
- Arrays whose length is computed at run time.<br>
- Supported, but allocated stack space is not freed until the function returns (noted above).</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
+
+ 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 X86 targets)
+ 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>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>noreturn</tt>, <tt>regparm</tt>
+ <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
+ <tt>noreturn</tt>, <tt>nothrow</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>noinline</tt>,
- <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
- <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
-
- <b>Unsupported:</b> All other target specific attributes</li>
-
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
- Specifying attributes of variables.<br>
- <b>Supported:</b> <tt>alias</tt>, <tt>cleanup</tt>, <tt>common</tt>,
- <tt>nocommon</tt>, <tt>deprecated</tt>, <tt>dllimport</tt>,
- <tt>dllexport</tt>, <tt>section</tt>, <tt>transparent_union</tt>,
- <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
-
- <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
- <tt>shared</tt>, <tt>tls_model</tt>,
- <tt>vector_size</tt>, all target specific attributes.
- </li>
-
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
- <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
- <tt>deprecated</tt>, <tt>may_alias</tt><br>
-
- <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
- all target specific attributes.</li>
-
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
- Other built-in functions.<br>
- We support all builtins which have a C language equivalent (e.g.,
- <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
- <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
- <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
- (currently ignored). We also support builtins for ISO C99 floating
- point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
- <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
- <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
+ <b>Ignored:</b> <tt>malloc</tt>,
+ <tt>no_instrument_function</tt></li>
</ol>
-
- <p>The following extensions <b>are</b> known to be supported:</p>
-
- <ol>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
-or arrays as values.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character <ESC>.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
- </ol></li>
+</li>
</ul>
itself, Qt, Mozilla, etc.</p>
<ul>
-<li>llvm-gcc4 only has partial support for <a href="http://llvm.org/PR870">C++
-Exception Handling</a>, and it is not enabled by default.</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.
+It works well for x86-64 darwin but not x86-64 linux.</li>
</ul>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ada-fe">Known problems with the Ada front-end</a>
+</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.
+<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>
+which does support trampolines.</li>
+<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
+Workaround: configure with --disable-bootstrap.</li>
+<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
+fail (c380004 also fails with gcc-4.2 mainline).</li>
+<li>Many 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>
+<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
+or finish at a non-byte offset</a> in a record. Workaround: do not pack records
+or use representation clauses that result in a field of a non-discrete type
+starting or finishing in the middle of a byte.</li>
+<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
+as generated by the Ada binder to be invalid</a>.
+Workaround: hand edit the file to use pointers for argv and envp rather than
+integers.</li>
+<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
+</ul>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="fortran-fe">Known problems with the Fortran front-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
+<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
+</ul>
+</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
<div class="doc_text">
<p>A wide variety of additional information is available on the <a
-href="http://llvm.org">LLVM web page</a>, including <a
-href="http://llvm.org/docs/">documentation</a> and <a
-href="http://llvm.org/pubs/">publications describing algorithms and
-components implemented in LLVM</a>. The web page also contains versions of the
-API documentation which is up-to-date with the CVS version of the source code.
+href="http://llvm.org">LLVM web page</a>, in particular in the <a
+href="http://llvm.org/docs/">documentation</a> section. The web page also
+contains versions of the API documentation which is up-to-date with the
+Subversion version of the source code.
You can access versions of these documents specific to this release by going
into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
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+ src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
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+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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