+ width="136" height="136" alt="LLVM Dragon Logo">
This document contains the release notes for the LLVM Compiler -Infrastructure, release 2.7. Here we describe the status of LLVM, including +Infrastructure, release 2.8. 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 LLVM releases web site.
@@ -60,10 +61,6 @@ main LLVM web page, this document applies to the next release, not the current one. To see the release notes for a specific release, please see the releases page. - -FIXME: llvm.org moved to new server, mention new logo, Ted and Doug new code - owners.
--The LLVM 2.7 distribution currently consists of code from the core LLVM +The LLVM 2.8 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 @@ -123,27 +108,38 @@ development. Here we include updates on these subprojects.
The Clang project is ...
- -In the LLVM 2.7 time-frame, the Clang team has made many improvements:
- -Clang is an LLVM front end for the C, +C++, and Objective-C languages. Clang aims to provide a better user experience +through expressive diagnostics, a high level of conformance to language +standards, fast compilation, and low memory use. Like LLVM, Clang provides a +modular, library-based architecture that makes it suitable for creating or +integrating with other development tools. Clang is considered a +production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86 +(32- and 64-bit), and for darwin-arm targets.
+ +In the LLVM 2.8 time-frame, the Clang team has made many improvements:
+ +-Wmissing-field-initializers, -Wshadow, -Wno-protocol, -Wtautological-compare, -Wstrict-selector-match, -Wcast-align, -Wunused improvements, and greatly improved format-string checking.#pragma GCC visibility, #pragma align, and others.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 automatically finding bugs -in C and Objective-C programs. The tool performs checks to find -bugs that occur on a specific path within a program.
+The Clang Static Analyzer + project is an effort to use static source code analysis techniques to + automatically find bugs in C and Objective-C programs (and hopefully C++ in the + future!). The tool is very good at finding bugs that occur on specific + paths through code, such as on error conditions.
-In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...
+The LLVM 2.8 release fixes a number of bugs and slightly improves precision + over 2.7, but there are no major new features in the release. +
-The VMKit project 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.
+DragonEgg is a port of llvm-gcc to +gcc-4.5. Unlike llvm-gcc, dragonegg in theory does not require any gcc-4.5 +modifications whatsoever (currently one small patch is needed) thanks to the +new gcc plugin architecture. +DragonEgg is a gcc plugin that makes gcc-4.5 use the LLVM optimizers and code +generators instead of gcc's, just like with llvm-gcc. +-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:
+DragonEgg is still a work in progress, but it is able to compile a lot of code, +for example all of gcc, LLVM and clang. Currently Ada, C, C++ and Fortran work +well, while 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 and darwin (darwin may need additional gcc patches). + ++The 2.8 release has the following notable changes:
+The VMKit project is an implementation of +a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and +just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage +collectors, and can be configured to use MMTk's copy mark-sweep garbage +collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained. +
+All of the code in the compiler-rt project is available under the standard LLVM -License, a "BSD-style" license.
+License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports +soft floating point (for targets that don't have a real floating point unit), +and includes an extensive testsuite for the "blocks" language feature and the +blocks runtime included in compiler_rt.-DragonEgg 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 -gcc plugin architecture, 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! -
+LLDB is a brand new member of the LLVM +umbrella of projects. LLDB is a next generation, high-performance debugger. It +is built as a set of reusable components which highly leverage existing +libraries in the larger LLVM Project, such as the Clang expression parser, the +LLVM disassembler and the LLVM JIT.-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. +LLDB is in early development and not included as part of the LLVM 2.8 release, +but is mature enough to support basic debugging scenarios on Mac OS X in C, +Objective-C and C++. We'd really like help extending and expanding LLDB to +support new platforms, new languages, new architectures, and new features.
++libc++ is another new member of the LLVM +family. It is an implementation of the C++ standard library, written from the +ground up to specifically target the forthcoming C++'0X standard and focus on +delivering great performance.
+-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. +As of the LLVM 2.8 release, libc++ is virtually feature complete, but would +benefit from more testing and better integration with Clang++. It is also +looking forward to the C++ committee finalizing the C++'0x standard.
-The LLVM Machine Code (MC) Toolkit project is ... +KLEE is a symbolic execution framework for +programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths +through the application and records state transitions that lead to fault +states. This allows it to construct testcases that lead to faults and can even +be used to verify some algorithms.
-Although KLEE does not have any major new features as of 2.8, we have made +various minor improvements, particular to ease development:
+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.
+ projects that have already been updated to work with LLVM 2.8.+TCE 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.
+ +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.
+Horizon is a bytecode +language and compiler written on top of LLVM, intended for producing +single-address-space managed code operating systems that +run faster than the equivalent multiple-address-space C systems. +More in-depth blurb is available on the wiki.
+ +-Need update. -
+The +ClamAV bytecode compiler uses Clang and LLVM to compile a C-like +language, insert runtime checks, and generate ClamAV bytecode.
Pure -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.
+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. -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).
+Pure versions 0.44 and later have been tested and are known to work with +LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).
-Need update. - -
+GHC is an open source, +state-of-the-art programming suite for +Haskell, a standard lazy functional programming language. It includes +an optimizing static compiler generating good code for a variety of +platforms, together with an interactive system for convenient, quick +development. + +In addition to the existing C and native code generators, GHC 7.0 now +supports an LLVM +code generator. GHC supports LLVM 2.7 and later.
+-Roadsend PHP (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. -
+Clay is a new systems programming +language that is specifically designed for generic programming. It makes +generic programming very concise thanks to whole program type propagation. It +uses LLVM as its backend. +-Unladen Swallow is a -branch of Python intended to be fully -compatible and significantly faster. It uses LLVM's optimization passes and JIT -compiler. -
+llvm-py has been updated to work +with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a +compiler backend or a VM in Python. +-Need update. - -
+FAUST is a compiled language for real-time +audio signal processing. The name FAUST stands for Functional AUdio STream. Its +programming model combines two approaches: functional programming and block +diagram composition. In addition with the C, C++, JAVA output formats, the +Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and +2.8. +-Need update. - -
+Jade +(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using +LLVM for just-in-time compilation of video decoder configurations. Those +configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee. +MPEG RVC standard is built on a stream-based dataflow representation of +decoders. It is composed of a standard library of coding tools written in +RVC-CAL language and a dataflow configuration — block diagram — +of a decoder.
+ +Jade project is hosted as part of the Open +RVC-CAL Compiler and requires it to translate the RVC-CAL standard library +of video coding tools into an LLVM assembly code.
+ +Neko LLVM JIT +replaces the standard Neko JIT with an LLVM-based implementation. While not +fully complete, it is already providing a 1.5x speedup on 64-bit systems. +Neko LLVM JIT requires LLVM 2.8 or later.
+ +-TCE 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.
+Crack aims to provide +the ease of development of a scripting language with the performance of a +compiled language. The language derives concepts from C++, Java and Python, +incorporating object-oriented programming, operator overloading and strong +typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release +builds on LLVM 2.8. -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.
+
+DTMC provides support for
+Transactional Memory, which is an easy-to-use and efficient way to synchronize
+accesses to shared memory. Transactions can contain normal C/C++ code (e.g.,
+__transaction { list.remove(x); x.refCount--; }) and will be executed
+virtually atomically and isolated from other transactions.
-SAFECode 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. +Kai (Japanese ä¼ for +meeting/gathering) is an experimental interpreter that provides a highly +extensible runtime environment and explicit control over the compilation +process. Programs are defined using nested symbolic expressions, which are all +parsed into first-class values with minimal intrinsic semantics. Kai can +generate optimised code at run-time (using LLVM) in order to exploit the nature +of the underlying hardware and to integrate with external software libraries. +It is a unique exploration into world of dynamic code compilation, and the +interaction between high level and low level semantics.
+ ++OSL is a shading +language designed for use in physically based renderers and in particular +production rendering. By using LLVM instead of the interpreter, it was able to +meet its performance goals (>= C-code) while retaining the benefits of +runtime specialization and a portable high-level language.
+LLVM 2.7 includes several major new capabilities:
+LLVM 2.8 includes several major new capabilities:
Also, -anders-aa was removed
++The LLVM Machine Code (aka MC) subsystem was created to solve a number +of problems in the realm of assembly, disassembly, object file format handling, +and a number of other related areas that CPU instruction-set level tools work +in.
+ +The MC subproject has made great leaps in LLVM 2.8. For example, support for + directly writing .o files from LLC (and clang) now works reliably for + darwin/x86[-64] (including inline assembly support) and the integrated + assembler is turned on by default in Clang for these targets. This provides + improved compile times among other things.
For more information, please see the Intro to the +LLVM MC Project Blog Post. +
+ + +New features of the X86 target include: -
- -New features of the PIC16 target include: +
New features and major changes in the X86 target include:
Things not yet supported:
- -+ insertps $113, %xmm3, %xmm0 # xmm0 = zero,xmm0[1,2],xmm3[1] + unpcklps %xmm1, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1] + pshufd $1, %xmm1, %xmm1 # xmm1 = xmm1[1,0,0,0] ++
New features of other targets include: -
- -This release includes a number of new APIs that are used internally, which - may also be useful for external clients. -
- -Other miscellaneous features include:
+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 +on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading from the previous release.
In addition, many APIs have changed in this release. Some of the major LLVM API changes are:
-LLVM is known to work on the following platforms:
+This section lists changes to the LLVM development infrastructure. This +mostly impacts users who actively work on LLVM or follow development on +mainline, but may also impact users who leverage the LLVM build infrastructure +or are interested in LLVM qualification.
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.
-The C backend has numerous problems and is not being actively maintained. +Depending on it for anything serious is not advised.
+The only major language feature of GCC not supported by llvm-gcc is - the __builtin_apply 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).
- -If you run into GCC extensions which are not supported, please let us know. -
- -llvm-gcc is generally very stable for the C family of languages. The only + major language feature of GCC not supported by llvm-gcc is the + __builtin_apply 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).
+ +Fortran support generally works, but there are still several unresolved bugs + in Bugzilla. Please see the + tools/gfortran component for details. Note that llvm-gcc is missing major + Fortran performance work in the frontend and library that went into GCC after + 4.2. If you are interested in Fortran, we recommend that you consider using + dragonegg instead.
+ +The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being +actively maintained. If you are interested in Ada, we recommend that you +consider using dragonegg instead.