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| <title>LLVM 2.7 Release Notes</title> |
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| <body> |
| |
| <div class="doc_title">LLVM 2.7 Release Notes</div> |
| |
| <img align=right src="http://llvm.org/img/DragonSmall.png" |
| width="136" height="136"> |
| |
| <ol> |
| <li><a href="#intro">Introduction</a></li> |
| <li><a href="#subproj">Sub-project Status Update</a></li> |
| <li><a href="#externalproj">External Projects Using LLVM 2.7</a></li> |
| <li><a href="#whatsnew">What's New in LLVM 2.7?</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> |
| <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> |
| |
| <!-- |
| <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.7 |
| release.<br> |
| You may prefer the |
| <a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6 |
| Release Notes</a>.</h1>--> |
| |
| <!-- *********************************************************************** --> |
| <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 2.7. Here we describe the status of LLVM, including |
| major improvements from the previous release and significant known problems. |
| All LLVM releases may be downloaded from the <a |
| 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://lists.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 release, please see the |
| <a href="http://llvm.org/releases/">releases page</a>.</p> |
| |
| |
| <p>FIXME: llvm.org moved to new server, mention new logo, Ted and Doug new code |
| owners.</p> |
| |
| </div> |
| |
| |
| <!-- |
| Almost dead code. |
| include/llvm/Analysis/LiveValues.h => Dan |
| lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8. |
| llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8. |
| ABCD, GEPSplitterPass |
| MSIL backend? |
| lib/Transforms/Utils/SSI.cpp -> ABCD depends on it. |
| --> |
| |
| |
| <!-- Features that need text if they're finished for 2.7: |
| gcc plugin. |
| strong phi elim |
| variable debug info for optimized code |
| postalloc scheduler: anti dependence breaking, hazard recognizer? |
| metadata |
| loop dependence analysis |
| ELF Writer? How stable? |
| <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li> |
| --> |
| |
| <!-- for announcement email: |
| Logo web page. |
| llvm devmtg |
| compiler_rt |
| KLEE web page at klee.llvm.org |
| Many new papers added to /pubs/ |
| Mention gcc plugin. |
| --> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="subproj">Sub-project Status Update</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| <p> |
| The LLVM 2.7 distribution currently consists of code from the core LLVM |
| repository (which roughly includes the LLVM optimizers, code generators |
| and supporting tools), the Clang repository and the llvm-gcc repository. In |
| addition to this code, the LLVM Project includes other sub-projects that are in |
| development. Here we include updates on these subprojects. |
| </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p> |
| |
| <p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p> |
| |
| <ul> |
| <li>FIXME: C++! Include a link to cxx_compatibility.html</li> |
| |
| <li>FIXME: Static Analyzer improvements?</li> |
| |
| <li>CIndex API and Python bindings: Clang now includes a C API as part of the |
| CIndex library. Although we make make some changes to the API in the future, it |
| is intended to be stable and has been designed for use by external projects. See |
| the Clang |
| doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a> |
| documentation for more details. The CIndex API also includings an preliminary |
| set of Python bindings.</li> |
| |
| <li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM |
| ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now |
| suitable for use as a a beta quality ARM compiler.</li> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="clangsa">Clang Static Analyzer</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also |
| includes an early stage static source code analysis tool for <a |
| href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a> |
| in C and Objective-C programs. The tool performs checks to find |
| bugs that occur on a specific path within a program.</p> |
| |
| <p>In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of |
| a JVM and a CLI Virtual Machine (Microsoft .NET is an |
| implementation of the CLI) using LLVM for static and just-in-time |
| compilation.</p> |
| |
| <p> |
| With the release of LLVM 2.7, VMKit has shifted to a great framework for writing |
| virtual machines. VMKit now offers precise and efficient garbage collection with |
| multi-threading support, thanks to the MMTk memory management toolkit, as well |
| as just in time and ahead of time compilation with LLVM. The major changes in |
| VMKit 0.27 are:</p> |
| |
| <ul> |
| |
| <li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors. |
| The first collector to be ported is the MarkSweep collector, which is precise, |
| and drastically improves the performance of VMKit.</li> |
| <li>Line number information in the JVM: by using the debug metadata of LLVM, the |
| JVM now supports precise line number information, useful when printing a stack |
| trace.</li> |
| <li>Interface calls in the JVM: we implemented a variant of the Interface Method |
| Table technique for interface calls in the JVM. |
| </li> |
| |
| </ul> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a> |
| is a simple library that provides an implementation of the low-level |
| target-specific hooks required by code generation and other runtime components. |
| For example, when compiling for a 32-bit target, converting a double to a 64-bit |
| unsigned integer is compiled into a runtime call to the "__fixunsdfdi" |
| function. The compiler-rt library provides highly optimized implementations of |
| this and other low-level routines (some are 3x faster than the equivalent |
| libgcc routines).</p> |
| |
| <p> |
| All of the code in the compiler-rt project is available under the standard LLVM |
| License, a "BSD-style" license.</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to |
| gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying |
| gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications |
| whatsoever (currently one small patch is needed). This is thanks to the new |
| <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which |
| makes it possible to modify the behaviour of gcc at runtime by loading a plugin, |
| which is nothing more than a dynamic library which conforms to the gcc plugin |
| interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run |
| instead of the gcc optimizers, and the LLVM code generators instead of the gcc |
| code generators, just like llvm-gcc. To use it, you add |
| "-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically |
| becomes llvm-gcc-4.5! |
| </p> |
| |
| <p> |
| DragonEgg is still a work in progress. Currently C works very well, while C++, |
| Ada and Fortran work fairly well. All other languages either don't work at all, |
| or only work poorly. For the moment only the x86-32 and x86-64 targets are |
| supported, and only on linux. |
| </p> |
| |
| <p> |
| DragonEgg has not yet been released. Once gcc-4.5 has been released, dragonegg |
| will probably be released as part of the following LLVM release. |
| </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="mc">llvm-mc: Machine Code Toolkit</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The LLVM Machine Code (MC) Toolkit project is ... |
| </p> |
| |
| </div> |
| |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="externalproj">External Open Source Projects Using LLVM 2.7</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>An exciting aspect of LLVM is that it is used as an enabling technology for |
| a lot of other language and tools projects. This section lists some of the |
| projects that have already been updated to work with LLVM 2.7.</p> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="Rubinius">Rubinius</a> |
| </div> |
| |
| <div class="doc_text"> |
| Need update. |
| <!-- |
| <p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment |
| for running Ruby code which strives to write as much of the core class |
| implementation in Ruby as possible. Combined with a bytecode interpreting VM, it |
| uses LLVM to optimize and compile ruby code down to machine code. Techniques |
| such as type feedback, method inlining, and uncommon traps are all used to |
| remove dynamism from ruby execution and increase performance.</p> |
| |
| <p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing |
| a counter based JIT, type feedback and speculative method inlining. |
| --> |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="macruby">MacRuby</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p> |
| Need update. |
| <!-- |
| <a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of |
| core Mac OS X technologies, such as the Objective-C common runtime and garbage |
| collector and the CoreFoundation framework. It is principally developed by |
| Apple and aims at enabling the creation of full-fledged Mac OS X applications. |
| </p> |
| |
| <p> |
| MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby |
| expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception |
| handling.--> </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="pure">Pure</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://pure-lang.googlecode.com/">Pure</a> |
| is an algebraic/functional programming language based on term rewriting. |
| Programs are collections of equations which are used to evaluate expressions in |
| a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation, |
| lexical closures, a hygienic macro system (also based on term rewriting), |
| built-in list and matrix support (including list and matrix comprehensions) and |
| an easy-to-use C interface. The interpreter uses LLVM as a backend to |
| JIT-compile Pure programs to fast native code.</p> |
| |
| <p>Pure versions 0.43 and later have been tested and are known to work with |
| LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="ldc">LLVM D Compiler</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| Need update. |
| <!-- |
| <a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of |
| the D Programming Language using the LLVM optimizer and code generator. |
| The LDC project works great with the LLVM 2.6 release. General improvements in |
| this |
| cycle have included new inline asm constraint handling, better debug info |
| support, general bug fixes and better x86-64 support. This has allowed |
| some major improvements in LDC, getting it much closer to being as |
| fully featured as the original DMD compiler from DigitalMars.--> |
| </p> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="RoadsendPHP">Roadsend PHP</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open |
| source implementation of the PHP programming |
| language that uses LLVM for its optimizer, JIT and static compiler. This is a |
| reimplementation of an earlier project that is now based on LLVM. |
| </p> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="UnladenSwallow">Unladen Swallow</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a |
| branch of <a href="http://python.org/">Python</a> intended to be fully |
| compatible and significantly faster. It uses LLVM's optimization passes and JIT |
| compiler. |
| </p> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="llvm-lua">llvm-lua</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| Need update. |
| <!-- |
| <a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT |
| and static compiling support to the Lua VM. Lua bytecode is analyzed to |
| remove type checks, then LLVM is used to compile the bytecode down to machine |
| code.--> |
| </p> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="icedtea">IcedTea Java Virtual Machine Implementation</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| Need update. |
| <!-- |
| <a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a |
| harness to build OpenJDK using only free software build tools and to provide |
| replacements for the not-yet free parts of OpenJDK. One of the extensions that |
| IcedTea provides is a new JIT compiler named <a |
| href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM |
| to provide native code generation without introducing processor-dependent |
| code.--> |
| </p> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="tce">TTA-based Codesign Environment (TCE)</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing |
| application-specific processors (ASP) based on the Transport triggered |
| architecture (TTA). The toolset provides a complete co-design flow from C/C++ |
| programs down to synthesizable VHDL and parallel program binaries. Processor |
| customization points include the register files, function units, supported |
| operations, and the interconnection network.</p> |
| |
| <p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target |
| independent optimizations and also for parts of code generation. It generates |
| new LLVM-based code generators "on the fly" for the designed TTA processors and |
| loads them in to the compiler backend as runtime libraries to avoid per-target |
| recompilation of larger parts of the compiler chain.</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="safecode">SAFECode Compiler</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C |
| compiler built using LLVM. It takes standard, unannotated C code, analyzes the |
| code to ensure that memory accesses and array indexing operations are safe, and |
| instruments the code with run-time checks when safety cannot be proven |
| statically. |
| </p> |
| </div> |
| |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="whatsnew">What's New in LLVM 2.7?</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This release includes a huge number of bug fixes, performance tweaks and |
| minor improvements. Some of the major improvements and new features are listed |
| in this section. |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="majorfeatures">Major New Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>LLVM 2.7 includes several major new capabilities:</p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| Extensible metadata solid. |
| |
| Debug info improvements: using metadata instead of llvm.dbg global variables. |
| This brings several enhancements including improved compile times. |
| |
| New instruction selector. |
| GHC Haskell ABI/ calling conv support. |
| Pre-Alpha support for unions in IR. |
| New InlineHint and StackAlignment function attributes |
| Code generator MC'ized except for debug info and EH. |
| New SCEV AA pass: -scev-aa |
| Inliner reuses arrays allocas when inlining multiple callers to reduce stack usage. |
| MC encoding and disassembler apis. |
| Optimal Edge Profiling? |
| Instcombine is now a library, has its own IRBuilder to simplify itself. |
| New llvm/Support/Regex.h API. FileCheck now does regex's |
| Many subtle pointer invalidation bugs in Callgraph have been fixed and it now uses asserting value handles. |
| MC Disassembler (with blog post), MCInstPrinter. Many X86 backend and AsmPrinter simplifications |
| Various tools like llc and opt now read either .ll or .bc files as input. |
| Malloc and free instructions got removed, along with LowerAllocations pass. |
| compiler-rt support for ARM. |
| completely llvm-gcc NEON support. |
| Can transcode from GAS to intel syntax with "llvm-mc foo.s -output-asm-variant=1" |
| JIT debug information with GDB 7.0 |
| New CodeGen Level CSE |
| CMake can now run tests, what other improvements? |
| ARM/Thumb using reg scavenging for stack object address materialization (PEI). |
| New SSAUpdater and MachineSSAUpdater classes for unstructured ssa updating, |
| changed jump threading, GVN, etc to use it which simplified them and speed |
| them up. |
| Combiner-AA improvements, why not on by default? |
| Pre-regalloc tail duplication |
| x86 sibcall / tailcall optimization in CCC mode. |
| New LSR with full strength reduction mode |
| The most awesome sext / zext optimization pass. ? |
| Better code size analysis in loop unswitch, inliner code split out to a new |
| CodeMetrics class for reuse. |
| The ARM backend now has good support for ARMv4 backend (tested on StrongARM |
| hardware), previously only supported ARMv4T and newer. |
| Half-float support in APFloat |
| Indirect branch + address of label (blog post), particularly useful for interpreters. |
| Many changes to the pass ordering for improved optimization effectiveness. |
| |
| Opt now works conservatively if no target data is set (is this fully working?) |
| Target data now has notion of 'native' integer data types which optimizations can use. |
| ARM backend generates instructions in unified assembly syntax. |
| New Analysis/InstructionSimplify.h interface for simplifying instructions that don't exist. |
| Jump threading is now much more aggressive at simplifying correlated |
| conditionals and threading blocks with otherwise complex logic. CondProp pass |
| removed (functionality merged into jump threading). |
| X86 and XCore supports returning arbitrary return values, returning too many values is |
| supported by returning through a hidden pointer. |
| verbose-asm now produces information about spill slots and loop nests |
| |
| |
| Defaults to RTTI off, packagers should build with make REQUIRE_RTTI=1. |
| AndersAA got removed (from 2.7 or mainline?) |
| PredSimplify, LoopVR, GVNPRE got removed. |
| LLVM command line tools now overwrite their output, before they would only do this with -f. |
| DOUT removed, use DEBUG(errs() instead. |
| Much stuff converted to use raw_ostream instead of std::ostream. |
| TargetAsmInfo renamed to MCAsmInfo |
| llvm/ADT/iterator.h gone. |
| |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="coreimprovements">LLVM IR and Core Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>LLVM IR has several new features for better support of new targets and that |
| expose new optimization opportunities:</p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="optimizer">Optimizer Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>In addition to a large array of minor performance tweaks and bug fixes, this |
| release includes a few major enhancements and additions to the optimizers:</p> |
| |
| <ul> |
| |
| <li>...</li> |
| |
| </ul> |
| |
| <p>Also, -anders-aa was removed</p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="executionengine">Interpreter and JIT Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li>The JIT now <a |
| href="http://llvm.org/viewvc/llvm-project?view=rev&revision=85295">defaults |
| to compiling eagerly</a> to avoid a race condition in the lazy JIT. |
| Clients that still want the lazy JIT can switch it on by calling |
| <tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li> |
| <li>It is now possible to create more than one JIT instance in the same process. |
| These JITs can generate machine code in parallel, |
| although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you |
| still have to obey the other threading restrictions</a>.</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="codegen">Target Independent Code Generator Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>We have put a significant amount of work into the code generator |
| infrastructure, which allows us to implement more aggressive algorithms and make |
| it run faster:</p> |
| |
| <ul> |
| |
| <li>...</li> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="x86">X86-32 and X86-64 Target Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of the X86 target include: |
| </p> |
| |
| <ul> |
| |
| <li>...</li> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="pic16">PIC16 Target Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of the PIC16 target include: |
| </p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| <p>Things not yet supported:</p> |
| |
| <ul> |
| <li>Variable arguments.</li> |
| <li>Interrupts/programs.</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="ARM">ARM Target Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of the ARM target include: |
| </p> |
| |
| <ul> |
| |
| <li>...</li> |
| </ul> |
| |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="OtherTarget">Other Target Specific Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of other targets include: |
| </p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="newapis">New Useful APIs</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>This release includes a number of new APIs that are used internally, which |
| may also be useful for external clients. |
| </p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="otherimprovements">Other Improvements and New Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>Other miscellaneous features include:</p> |
| |
| <ul> |
| <li>...</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="changes">Major Changes and Removed Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>If you're already an LLVM user or developer with out-of-tree changes based |
| on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading |
| from the previous release.</p> |
| |
| <ul> |
| <li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even |
| if you have it installed. This makes it more likely that an LLVM built on one |
| system will work when copied to a similar system. To use <tt>libffi</tt>, |
| configure with <tt>--enable-libffi</tt>. |
| </li> |
| </ul> |
| |
| |
| <p>In addition, many APIs have changed in this release. Some of the major LLVM |
| API changes are:</p> |
| |
| <ul> |
| <li><tt>ModuleProvider</tt> has been <a |
| href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a> |
| and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>. |
| Most clients can remove uses of <tt>ExistingModuleProvider</tt>, |
| replace <tt>getBitcodeModuleProvider</tt> with |
| <tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to |
| functions that used to accept <tt>ModuleProvider</tt>. Clients who |
| wrote their own <tt>ModuleProvider</tt>s will need to derive from |
| <tt>GVMaterializer</tt> instead and use |
| <tt>Module::setMaterializer</tt> to attach it to a |
| <tt>Module</tt>.</li> |
| |
| <li><tt>GhostLinkage</tt> has given up the ghost. |
| <tt>GlobalValue</tt>s that have not yet been read from their backing |
| storage have the same linkage they will have after being read in. |
| Clients must replace calls to |
| <tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with |
| <tt>GlobalValue::isMaterializable</tt>.</li> |
| |
| <li>FIXME: Debug info has been totally redone. Add pointers to new APIs. Substantial caveats about compatibility of .ll and .bc files.</li> |
| |
| <li>The <tt>llvm/Support/DataTypes.h</tt> header has moved |
| to <tt>llvm/System/DataTypes.h</tt>.</li> |
| |
| <li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>, |
| <tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed |
| <tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>, |
| <tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</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 (IA32, X86-64, AMD64, EMT-64) running Red Hat |
| Linux, Fedora Core, FreeBSD and AuroraUX (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 x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li> |
| <li>Alpha-based machines running Debian GNU/Linux.</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 significant known problems with the LLVM system, |
| listed by component. If you run into a problem, please check the <a |
| href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if |
| there isn't already one.</p> |
| |
| <ul> |
| <li>LLVM will not correctly compile on Solaris and/or OpenSolaris |
| using the stock GCC 3.x.x series 'out the box', |
| See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>. |
| However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a> |
| for x86/x86-64 has been made available from the third party AuroraUX Project |
| that has been meticulously tested for bootstrapping LLVM & Clang.</li> |
| </ul> |
| |
| </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, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze |
| backends are experimental.</li> |
| <li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only |
| supported value for this option. The MachO writer is experimental, and |
| works much better in mainline SVN.</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 |
| all <a href="http://llvm.org/PR879">inline assembly that uses the X86 |
| floating point stack</a>. It supports the 'f' and 't' constraints, but not |
| 'u'.</li> |
| <li>The X86 backend generates inefficient floating point code when configured |
| to generate code for systems that don't have SSE2.</li> |
| <li>Win64 code generation wasn't widely tested. Everything should work, but we |
| expect small issues to happen. Also, llvm-gcc cannot build the mingw64 |
| runtime currently due |
| to <a href="http://llvm.org/PR2255">several</a> |
| <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for |
| the |
| 'u' inline assembly constraint and for X87 floating point inline assembly.</li> |
| <li>The X86-64 backend does not yet support the LLVM IR instruction |
| <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic |
| argument constructs on X86-64 by lowering them manually.</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>Support for the Advanced SIMD (Neon) instruction set is still incomplete |
| and not well tested. Some features may not work at all, and the code quality |
| may be poor in some cases.</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> |
| </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="mips-be">Known problems with the MIPS back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li>64-bit MIPS targets are not supported yet.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="alpha-be">Known problems with the Alpha back-end</a> |
| </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="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 <tt>llc</tt> or native compilers.</li> |
| <li>The C backend does not support all exception handling constructs.</li> |
| <li>The C backend does not support arbitrary precision integers.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <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 (these 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="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| <ul> |
| <li>Fortran support generally works, but there are still several unresolved bugs |
| in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the |
| tools/gfortran component for details.</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>. |
| This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style |
| exception handling, which is used internally by the compiler. |
| Workaround: configure with <tt>--disable-bootstrap</tt>.</li> |
| <li>The c380004, <a href="http://llvm.org/PR2010">c393010</a> |
| and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail |
| (c380004 also fails with gcc-4.2 mainline). |
| If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a> |
| causes the compiler to go into an infinite loop, using up all system memory.</li> |
| <li>Some GCC specific Ada tests continue to crash the compiler.</li> |
| <li>The <tt>-E</tt> 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 <tt>-E</tt>.</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 <tt>lli</tt> 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 <tt>argv</tt> and |
| <tt>envp</tt> rather than integers.</li> |
| <li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is |
| ignored</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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