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- <title>LLVM 1.8 Release Notes</title>
+ <title>LLVM 2.3 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 1.8 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 1.8. Here we describe the status of LLVM, including any
-known problems and major improvements from the previous release. The most
-up-to-date version of this document (corresponding to LLVM CVS) can be found
-on the <a
-href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
-not reading this on the LLVM web pages, you should probably go there because
-this document may be updated after the release.</p>
+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>.</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 ninth public release of the LLVM Compiler Infrastructure. This
-release incorporates a large number of enhancements and new features,
-including DWARF debugging support (C and C++ on Darwin/PPC), improved inline
-assembly support, a new <a href="http://llvm.org/nightlytest/">nightly
-tester</a>, llvm-config enhancements, many bugs
-fixed, and performance and compile time improvements.
-</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 1.8</a>
+<a name="deprecation">Removed features in LLVM 2.3</a>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="dwarf">DWARF debugging
-support </a></div>
-
<div class="doc_text">
-<p>The llvm-gcc4 C front-end now generates debugging info for C and C++. This
-information is propagated through the compiler and the code generator can
-currently produce DWARF debugging information from it. DWARF is a standard
-debugging format used on many platforms, but currently LLVM only includes
-target support for Mac OS X targets for the 1.8 release.
-</p>
+<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>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="inlineasm">Inline Assembly
-Support</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="frontends">llvm-gcc 4.2 and clang</a>
+</div>
<div class="doc_text">
-<p>Inline assembly support is substantially improved in LLVM 1.8 over LLVM 1.7.
-Many unsupported features are now supported, and inline asm support in the X86
-backend is far better. llvm-gcc4 now supports global register variables as
-well.</p>
+<p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end. </p>
+
+<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
+a set of new 'llvm native' front-end technologies for the LLVM optimizer
+and code generator. Currently, its C and Objective-C support is maturing
+nicely, and it has advanced source-to-source analysis and transformation
+capabilities. If you are interested in building source-level tools for C and
+Objective-C (and eventually C++), you should take a look. However, note that
+clang is not an official part of the LLVM 2.3 release. If you are interested in
+this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="loopopt">Loop Optimizer Improvements</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="majorfeatures">Major New Features</a>
+</div>
<div class="doc_text">
-<p>The loop optimizer passes now uses "Loop-Closed SSA Form", which makes it
-easier to update SSA form as loop transformations change the code. An
-immediate benefit of this is that the loop unswitching pass can now unswitch
-loops in more cases.
-</p>
+<p>LLVM 2.3 includes several major new capabilities:</p>
+
+<ul>
+</ul>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="jumptab">Jump Table Support for Switches
-</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="coreimprovements">LLVM Core Improvements</a>
+</div>
<div class="doc_text">
+<p>New features include:
+</p>
-<p>The code generator now lowers switch statements to jump tables, providing
-significant performance boosts for applications (e.g. interpreters) whose
-performance is highly correlated to switch statement performance.</p>
+<ul>
+</ul>
+
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="jitrelease">Deallocation of JIT'd
-Machine Code
-</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="codegen">Code Generator Improvements</a>
+</div>
<div class="doc_text">
-<p>The LLVM JIT now allows clients to deallocate machine code JIT'd to its code
-buffer. This is important for long living applications that depend on the JIT.
-</p>
+<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>
+
+<ul>
+<li>MemOperand in the code generator.</li>
+</ul>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="optimizer">Optimizer Improvements</a>
+</div>
<div class="doc_text">
-<p>This release includes many other improvements, including improvements to
- the optimizers and code generators (improving the generated code) changes to
- speed up the compiler in many ways (improving algorithms and fine tuning
- code), and changes to reduce the code size of the compiler itself.</p>
-
-<p>More specific changes include:</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>LLVM 1.8 includes an initial ARM backend. This backend is in early
- development stages.</li>
-<li>LLVM 1.8 now includes significantly better support for mingw and
- cygwin.</li>
-<li>The <a href="CommandGuide/html/llvm-config.html">llvm-config</a> tool is
- now built by default and has several new features.</li>
-<li>The X86 and PPC backends now use the correct platform ABI for passing
- vectors as arguments to functions.</li>
-<li>The X86 backend now includes support for the Microsoft ML assembler
- ("MASM").</li>
-<li>The PowerPC backend now pattern matches the 'rlwimi' instruction more
- aggressively.</li>
-<li>Most of LLVM is now built with "-pedantic", ensuring better portability
- to more C++ Compilers.</li>
-<li>The PowerPC backend now includes initial 64-bit support. The JIT is not
- complete, and the static compiler has a couple of known bugs, but support
- is mostly in place. LLVM 1.9 will include completed PPC-64 support. </li>
+
+<li>Index set splitting on by default.</li>
</ul>
+
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="changes">Significant Changes in LLVM 1.8</a>
+<a name="targetspecific">Target Specific Improvements</a>
</div>
<div class="doc_text">
+<p>New target-specific features include:
+</p>
+
<ul>
-<li>The LLVM "SparcV9" backend (deprecated in LLVM 1.7) has been removed in
-LLVM 1.8. The LLVM "Sparc" backend replaces it.</li>
-<li>The --version option now prints more useful information, including the
- build configuration for the tool.</li>
</ul>
+
</div>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="otherimprovements">Other Improvements</a>
+</div>
+
+<div class="doc_text">
+<p>New features include:
+</p>
+
+<ul>
+</ul>
+
+</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<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.</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>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>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="build">Known problems with the Build System</a>
+ <a name="x86-be">Known problems with the X86 back-end</a>
</div>
<div class="doc_text">
<ul>
-<li>none yet</li>
+<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_subsection">
- <a name="core">Known problems with the LLVM Core</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
- <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
- work.</li>
-</ul>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c-fe">Known problems with the C front-end</a>
+ <a name="ppc-be">Known problems with the PowerPC back-end</a>
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">Bugs</div>
-
<div class="doc_text">
-<p>
-llvm-gcc3 has many significant problems that are fixed by llvm-gcc4.
-Two major ones include:</p>
-
<ul>
-<li>With llvm-gcc3,
- C99 variable sized arrays do not release stack memory when they go out of
- scope. Thus, the following program may run out of stack space:
-<pre>
- for (i = 0; i != 1000000; ++i) {
- int X[n];
- foo(X);
- }
-</pre></li>
-
-<li>With llvm-gcc3, Initialization of global union variables can only be done <a
-href="http://llvm.org/PR162">with the largest union member</a>.</li>
-
+<li>The Linux PPC32/ABI support needs testing for the interpreter and static
+compilation, and lacks support for debug information.</li>
</ul>
-<p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
-does not currently support Link-Time-Optimization or C++ Exception Handling,
-which llvm-gcc3 does.</p>
-
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- Notes
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="arm-be">Known problems with the ARM back-end</a>
</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>The following Unix system functionality has not been tested and may not
-work:
- <ol>
- <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
- appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
- <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
- <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
- - These functions have not been tested.
- </ol></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/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/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>
-
- <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/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>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
- <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
- <tt>unused</tt>, <tt>used</tt>,
- <tt>deprecated</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> <tt>section</tt>, <tt>alias</tt>,
- <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
- <tt>fastcall</tt>, 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>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
- <tt>deprecated</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>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
- <tt>vector_size</tt>, <tt>dllimport</tt>,
- <tt>dllexport</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>
- </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/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>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>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>
-<p>If you run into GCC extensions which have not been included in any of these
-lists, please let us know (also including whether or not they work).</p>
-
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c++-fe">Known problems with the C++ front-end</a>
-</div>
-
-<div class="doc_text">
-
-<p>For this release, the C++ front-end is considered to be fully
-tested and works for a number of non-trivial programs, including LLVM
-itself.</p>
-
+ <a name="sparc-be">Known problems with the SPARC back-end</a>
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">Bugs</div>
-
<div class="doc_text">
<ul>
-<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
- front-end</a>.</li>
-
+<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>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- Notes
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="alpha-be">Known problems with the Alpha back-end</a>
</div>
<div class="doc_text">
<ul>
-<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 is very
- different from the model used in the Itanium ABI, so <b>exceptions will not
- interact correctly</b>. </li>
+<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
+appropriate nops inserted to ensure restartability.</li>
</ul>
-
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c-be">Known problems with the C back-end</a>
+ <a name="ia64-be">Known problems with the IA64 back-end</a>
</div>
<div class="doc_text">
<ul>
-<li>The C back-end produces code that violates the ANSI C Type-Based Alias
-Analysis rules. As such, special options may be necessary to compile the code
-(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
-problem probably cannot be fixed.</li>
+<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
+made where the argument is not 16-byte aligned, as required on IA64. (Strictly
+speaking this is not a bug in the IA64 back-end; it will also be encountered
+when building C++ programs using the C back-end.)</li>
+
+<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
+ABI compliant layout of v-tables</a>. In particular, it just stores function
+pointers instead of function descriptors in the vtable. This bug prevents
+mixing C++ code compiled with LLVM with C++ objects compiled by other C++
+compilers.</li>
-<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
-supported</a>. This should not affect LLVM produced by the C or C++
-frontends.</li>
+<li>There are a few ABI violations which will lead to problems when mixing LLVM
+output with code built with other compilers, particularly for floating-point
+programs.</li>
-<li>The C backend does not correctly implement the <a
-href="LangRef.html#i_stacksave"><tt>llvm.stacksave</tt></a> or
-<a href="LangRef.html#i_stackrestore"><tt>llvm.stackrestore</tt></a>
-intrinsics. This means that some code compiled by it can run out of stack
-space if they depend on these (e.g. C99 varargs).</li>
+<li>Defining vararg functions is not supported (but calling them is ok).</li>
+<li>The Itanium backend has bitrotted somewhat.</li>
</ul>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="x86-be">Known problems with the X86 back-end</a>
+ <a name="c-be">Known problems with the C back-end</a>
</div>
<div class="doc_text">
<ul>
-<li>none yet.</li>
+<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_subsection">
- <a name="ppc-be">Known problems with the PowerPC back-end</a>
+ <a name="c-fe">Known problems with the C front-end</a>
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">Bugs</div>
+
<div class="doc_text">
-<ul>
-<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
-implement ordered FP comparisons</a>.</li>
-</ul>
+<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
+Optimization</a> on most platforms "out-of-the-box". Please inquire on the
+llvmdev mailing list if you are interested.</p>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="alpha-be">Known problems with the Alpha back-end</a>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ Notes
</div>
<div class="doc_text">
-
<ul>
-<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
-appropriate nops inserted to ensure restartability.</li>
+<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
+ See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
+</li>
+
+<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
+ <ol>
+ <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>always_inline</tt>, <tt>cdecl</tt>,
+ <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
+ <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
+ <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
+ <tt>noreturn</tt>, <tt>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>malloc</tt>,
+ <tt>no_instrument_function</tt></li>
+ </ol>
+</li>
</ul>
+<p>If you run into GCC extensions which have not been included in any of these
+lists, please let us know (also including whether or not they work).</p>
+
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="ia64-be">Known problems with the IA64 back-end</a>
+ <a name="c++-fe">Known problems with the C++ front-end</a>
</div>
<div class="doc_text">
-<ul>
-
-<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
-made where the argument is not 16-byte aligned, as required on IA64. (Strictly
-speaking this is not a bug in the IA64 back-end; it will also be encountered
-when building C++ programs using the C back-end.)</li>
-
-<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
-ABI compliant layout of v-tables</a>. In particular, it just stores function
-pointers instead of function descriptors in the vtable. This bug prevents
-mixing C++ code compiled with LLVM with C++ objects compiled by other C++
-compilers.</li>
-
-<li>There are a few ABI violations which will lead to problems when mixing LLVM
-output with code built with other compilers, particularly for floating-point
-programs.</li>
-
-<li>Defining vararg functions is not supported (but calling them is ok).</li>
+<p>The C++ front-end is considered to be fully
+tested and works for a number of non-trivial programs, including LLVM
+itself, Qt, Mozilla, etc.</p>
+<ul>
+<li>Exception handling 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="sparc-be">Known problems with the SPARC back-end</a>
+ <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 SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
- support the 64-bit SPARC ABI (-m64).</li>
+<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="arm-be">Known problems with the ARM back-end</a>
+ <a name="fortran-fe">Known problems with the Fortran front-end</a>
</div>
<div class="doc_text">
<ul>
-<li>The ARM backend is currently in early development stages, it is not
-ready for production use.</li>
+<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">
<a name="additionalinfo">Additional Information</a>
<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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+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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