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| <title>LLVM 2.3 Release Notes</title> |
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| <body> |
| |
| <div class="doc_title">LLVM 2.3 Release Notes</div> |
| |
| <ol> |
| <li><a href="#intro">Introduction</a></li> |
| <li><a href="#whatsnew">What's New?</a></li> |
| <li><a href="GettingStarted.html">Installation Instructions</a></li> |
| <li><a href="#portability">Portability and Supported Platforms</a></li> |
| <li><a href="#knownproblems">Known Problems</a> |
| <li><a href="#additionalinfo">Additional Information</a></li> |
| </ol> |
| |
| <div class="doc_author"> |
| <p>Written by the <a href="http://llvm.org">LLVM Team</a><p> |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="intro">Introduction</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This document contains the release notes for the LLVM compiler |
| 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 |
| web site</a>. If you have questions or comments, the <a |
| 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 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_section"> |
| <a name="whatsnew">What's New?</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This is the fourteenth public release of the LLVM Compiler Infrastructure. |
| It includes a large number of 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="deprecation">Removed features in LLVM 2.3</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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. One nice impact of this is that the LLVM regressionn |
| test suite no longer depends on llvm-upgrade, which makes it run faster.</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="majorfeatures">Major New Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>LLVM 2.3 includes several major new capabilities:</p> |
| |
| <ul> |
| <li>Multiple Return Value Support</li> |
| |
| |
| <li><p>LLVM 2.3 includes a complete reimplementation of the "llvmc" tool. It is |
| designed to overcome several problems of the original llvmc and to provide a |
| superset of the features as the 'gcc' driver.</p> |
| |
| <p>The main features of llvmc2 is:</p> |
| |
| <ul> |
| <li>Extended handling of command line options and smart rules for |
| dispatching them to different tools.</li> |
| <li>Flexible (and extensible) rules for defining different tools.</li> |
| <li>The different intermediate steps performed by tools are represented |
| as edged in the abstract graph.</li> |
| </l>The 'language' for driver behaviour definition is tablegen and thus |
| it's relatively easy to add new features.</li> |
| <li>The definition of driver is transformed into set of C++ classes, thus |
| no runtime interpretation is needed.</li> |
| </ul> |
| |
| </li> |
| |
| |
| |
| |
| </ul> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="frontends">llvm-gcc 4.2 Improvements and Clang</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end.</p> |
| |
| <p>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C |
| front-end. Objective-C now works very well on Mac OS/X.</p> |
| |
| <p>llvm-gcc 4.2 includes many other fixes which improve conformance with the |
| relevant parts of the GCC testsuite.</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_subsection"> |
| <a name="coreimprovements">LLVM Core Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features include: |
| </p> |
| |
| |
| Common linkage? |
| |
| Atomic operation support, Alpha, X86, PowerPC. "__sync_syncronize" |
| |
| <ul> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="codegen">Code Generator Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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: describe me!.</li> |
| <li>i128 support and APInt through most of codegen.</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="optimizer">Optimizer Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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>Loop index set splitting on by default: describe me.</li> |
| <li>LLVM includes a new memcpy optimization pass which optimizes out dead |
| memcpy calls and unneeded copies of aggregates.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="targetspecific">Target Specific Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New target-specific features include: |
| </p> |
| |
| <ul> |
| <li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the |
| area of passing and returning structures by value. llvm-gcc Compiled code |
| now interoperates very well on X86-64 systems with other compilers.</li> |
| |
| <li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and |
| the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins.</li> |
| |
| <li>The X86 backend now does a number of optimizations that aim to avoid |
| converting numbers back and forth from SSE registers to the X87 floating |
| point stack.</li> |
| |
| <li>The X86 backend supports stack realignment, which is particularly useful for |
| vector code on OS's without 16-byte aligned stacks.</li> |
| |
| <li>The X86 backend now supports the "sseregparm" options in GCC, which allow |
| functions to be tagged as passing floating point values in SSE |
| registers.</li> |
| |
| <li>Trampolines (taking the address of a nested function) now work on |
| Linux/x86-64.</li> |
| |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="otherimprovements">Other Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features include: |
| </p> |
| |
| <ul> |
| <li>LLVM now builds with GCC 4.3.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="portability">Portability and Supported Platforms</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <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 |
| (and probably other unix-like systems).</li> |
| <li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and |
| 64-bit modes.</li> |
| <li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li> |
| <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited |
| support is available for native builds with Visual C++).</li> |
| <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> |
| |
| <p>The core LLVM infrastructure uses GNU autoconf to adapt itself |
| to the machine and operating system on which it is built. However, minor |
| porting may be required to get LLVM to work on new platforms. We welcome your |
| portability patches and reports of successful builds or error messages.</p> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="knownproblems">Known Problems</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This section contains all known problems with the LLVM system, listed by |
| component. As new problems are discovered, they will be added to these |
| sections. If you run into a problem, please check the <a |
| href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if |
| there isn't already one.</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="experimental">Experimental features included with this release</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>The following components of this LLVM release are either untested, known to |
| 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> |
| |
| <ul> |
| <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> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="x86-be">Known problems with the X86 back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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 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="ppc-be">Known problems with the PowerPC back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li>The Linux PPC32/ABI support needs testing for the interpreter and static |
| compilation, and lacks support for debug information.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="arm-be">Known problems with the ARM back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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> |
| <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> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="sparc-be">Known problems with the SPARC back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <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_subsection"> |
| <a name="alpha-be">Known problems with the Alpha back-end</a> |
| </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> |
| |
| </ul> |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="ia64-be">Known problems with the IA64 back-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> |
| |
| <li>The Itanium backend has bitrotted somewhat.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="c-be">Known problems with the C back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li><a href="http://llvm.org/PR802">The C backend has only basic support for |
| 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> |
| <li>The C backend does not support all exception handling constructs.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="c-fe">Known problems with the llvm-gcc C front-end</a> |
| </div> |
| |
| <!-- _______________________________________________________________________ --> |
| <div class="doc_subsubsection">Bugs</div> |
| |
| <div class="doc_text"> |
| |
| <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>The only major language feature of GCC not supported by llvm-gcc is |
| the <tt>__builtin_apply</tt> family of builtins. However, some extensions |
| are only supported on some targets. For example, trampolines are only |
| supported on some targets, which are used when you take the address of a |
| nested function.</p> |
| |
| <p>If you run into GCC extensions which are not supported, please let us know. |
| </p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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 works well on the X86 and PowerPC targets, including |
| x86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is |
| supported on x86-64 linux, but that is disabled by default in this release.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="ada-fe">Known problems with the llvm-gcc 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 llvm-gcc 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"> |
| <a name="additionalinfo">Additional Information</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>A wide variety of additional information is available on the <a |
| 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> |
| |
| <p>If you have any questions or comments about LLVM, please feel free to contact |
| us via the <a href="http://llvm.org/docs/#maillist"> mailing |
| lists</a>.</p> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| |
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