@@ -17,35 +16,35 @@
This document contains the release notes for the LLVM Compiler -Infrastructure, release 2.8. Here we describe the status of LLVM, including +Infrastructure, release 3.0. 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.
@@ -62,51 +61,37 @@ current one. To see the release notes for a specific release, please see the releases page.-The LLVM 2.8 distribution currently consists of code from the core LLVM +The LLVM 3.0 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.
-Clang is an LLVM front end for the C, C++, and Objective-C languages. Clang aims to provide a better user experience @@ -115,96 +100,51 @@ 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:
+(32- and 64-bit), and for darwin/arm targets. -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.
- -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. +
In the LLVM 3.0 time-frame, the Clang team has made many improvements:
+ +If Clang rejects your code but another compiler accepts it, please take a +look at the language +compatibility guide to make sure this is not intentional or a known issue.
-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. +DragonEgg is a +gcc plugin that replaces GCC's +optimizers and code generators with LLVM's. +Currently it requires a patched version of gcc-4.5. +The plugin can target the x86-32 and x86-64 processor families and has been +used successfully on the Darwin, FreeBSD and Linux platforms. +The Ada, C, C++ and Fortran languages work well. +The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is +not known whether the compiled code actually works or not!
-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 3.0 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. -
The new LLVM compiler-rt project is a simple library that provides an implementation of the low-level @@ -215,21 +155,16 @@ 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).
--All of the code in the compiler-rt project is available under the standard LLVM -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.
+In the LLVM 3.0 timeframe,
LLDB is a brand new member of the LLVM umbrella of projects. LLDB is a next generation, high-performance debugger. It @@ -238,445 +173,327 @@ libraries in the larger LLVM Project, such as the Clang expression parser, the LLVM disassembler and the LLVM JIT.
-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. -
+LLDB is has advanced by leaps and bounds in the 3.0 timeframe. It is +dramatically more stable and useful, and includes both a new tutorial and a side-by-side comparison with +GDB.-libc++ is another new member of the LLVM +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.
-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. +In the LLVM 3.0 timeframe,
+ ++Like compiler_rt, libc++ is now dual + licensed under the MIT and UIUC license, allowing it to be used more + permissively.
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 2.8.
--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.
- + + LLBrowse is an interactive viewer for LLVM modules. It can load any LLVM + module and displays its contents as an expandable tree view, facilitating an + easy way to inspect types, functions, global variables, or metadata nodes. It + is fully cross-platform, being based on the popular wxWidgets GUI toolkit. +-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.
- +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 3.0, VMKit now supports generational + garbage collectors. The garbage collectors are provided by the MMTk framework, + and VMKit can be configured to use one of the numerous implemented collectors + of MMTk. +
-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.
- -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).
+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 3.0.
- +-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.
- +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.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 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.
-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.
- -PinaVM is an open +source, SystemC front-end. Unlike many +other front-ends, PinaVM actually executes the elaboration of the +program analyzed using LLVM's JIT infrastructure. It later enriches the +bitcode with SystemC-specific information.
-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.
- + +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. The interpreter uses LLVM as a backend to JIT-compile Pure + programs to fast native code. 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 interface to C and other + programming languages (including the ability to load LLVM bitcode + modules, and inline C, C++, Fortran and Faust code in Pure programs if + the corresponding LLVM-enabled compilers are installed).
+ +Pure version 0.47 has been tested and is known to work with LLVM 3.0 + (and continues to work with older LLVM releases >= 2.5).
-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.
+IcedTea 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 Shark which uses LLVM +to provide native code generation without introducing processor-dependent +code. + +OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested +and are known to work with LLVM 3.0 (and continue to work with older LLVM +releases >= 2.6 as well).
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 &emdash; block diagram &emdash; -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.
+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.
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.
- +Polly is a project that aims to provide advanced memory access optimizations +to better take advantage of SIMD units, cache hierarchies, multiple cores or +even vector accelerators for LLVM. Built around an abstract mathematical +description based on Z-polyhedra, it provides the infrastructure to develop +advanced optimizations in LLVM and to connect complex external optimizers. In +its first year of existence Polly already provides an exact value-based +dependency analysis as well as basic SIMD and OpenMP code generation support. +Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality +and parallelism.
-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.
+Rubinius is an environment + for running Ruby code which strives to write as much of the 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 deoptimization are all used to remove dynamism + from ruby execution and increase performance.
-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.
- --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. -
- +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.
-LLVM 2.8 includes several major new capabilities:
+LLVM 3.0 includes several major new capabilities:
LLVM IR has several new features for better support of new targets and that expose new optimization opportunities:
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:
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.
-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:
New features of the X86 target include: +
New features and major changes in the X86 target include:
New features of the ARM target include:
Other miscellaneous features include:
+If you're already an LLVM user or developer with out-of-tree changes based -on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading -from the previous release.
+If you're already an LLVM user or developer with out-of-tree changes based on + LLVM 2.9, this section lists some "gotchas" that you may run into upgrading + from the previous release.
LowerSetJmp pass wasn't used effectively by any
+ target and has been removed.TailDup pass was not used in the standard pipeline
+ and was unable to update ssa form, so it has been removed.
+ load volatile"/"store volatile". The old
+ syntax ("volatile load"/"volatile store")
+ is still accepted, but is now considered deprecated.In addition, many APIs have changed in this release. Some of the major + LLVM API changes are:
-In addition, many APIs have changed in this release. Some of the major LLVM -API changes are:
PHINode::reserveOperandSpace has been removed. Instead, you
+ must specify how many operands to reserve space for when you create the
+ PHINode, by passing an extra argument into PHINode::Create.PHINode::block_begin
+ and PHINode::block_end.ArrayRef instead of either a pair
+ of pointers (or iterators) to the beginning and end of a range, or a pointer
+ and a length. Others now return an ArrayRef instead of a
+ reference to a SmallVector or std::vector. These
+ include:
+CallInst::CreateComputeLinearIndex (in llvm/CodeGen/Analysis.h)ConstantArray::getConstantExpr::getExtractElementConstantExpr::getGetElementPtrConstantExpr::getInBoundsGetElementPtrConstantExpr::getIndicesConstantExpr::getInsertElementConstantExpr::getWithOperandsConstantFoldCall (in llvm/Analysis/ConstantFolding.h)ConstantFoldInstOperands (in llvm/Analysis/ConstantFolding.h)ConstantVector::getDIBuilder::createComplexVariableDIBuilder::getOrCreateArrayExtractValueInst::CreateExtractValueInst::getIndexedTypeExtractValueInst::getIndicesFindInsertedValue (in llvm/Analysis/ValueTracking.h)gep_type_begin (in llvm/Support/GetElementPtrTypeIterator.h)gep_type_end (in llvm/Support/GetElementPtrTypeIterator.h)GetElementPtrInst::CreateGetElementPtrInst::CreateInBoundsGetElementPtrInst::getIndexedTypeInsertValueInst::CreateInsertValueInst::getIndicesInvokeInst::CreateIRBuilder::CreateCallIRBuilder::CreateExtractValueIRBuilder::CreateGEPIRBuilder::CreateInBoundsGEPIRBuilder::CreateInsertValueIRBuilder::CreateInvokeMDNode::getMDNode::getIfExistsMDNode::getTemporaryMDNode::getWhenValsUnresolvedSimplifyGEPInst (in llvm/Analysis/InstructionSimplify.h)TargetData::getIndexedOffsetStringMap::getOrCreateValue have been remove
+ except for the one which takes a StringRef.LLVMBuildUnwind function from the C API was removed. The
+ LLVM unwind instruction has been deprecated for a long time and
+ isn't used by the current front-ends. So this was removed during the
+ exception handling rewrite.LLVMAddLowerSetJmpPass function from the C API was removed
+ because the LowerSetJmp pass was removed.DIBuilder interface used by front ends to encode debugging
+ information in the LLVM IR now expects clients to use DIBuilder::finalize()
+ at the end of translation unit to complete debugging information encoding.This section contains significant known problems with the LLVM system, listed by component. If you run into a problem, please check the LLVM bug database and submit a bug if there isn't already one.
-The following components of this LLVM release are either untested, known to be broken or unreliable, or are in early development. These components should @@ -1002,43 +720,54 @@ components, please contact us on the LLVMdev list.
The C backend has numerous problems and is not being actively maintained. Depending on it for anything serious is not advised.
@@ -1130,11 +859,13 @@ Depending on it for anything serious is not advised. - + + +LLVM 3.0 will be the last release of llvm-gcc.
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 @@ -1150,49 +881,23 @@ Depending on it for anything serious is not advised.
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. However, this is not a -mature technology, and problems should be expected. For example:
-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.
+A wide variety of additional information is available on the LLVM web page, in particular in the LLVM web page, in particular in the documentation section. The web page also contains versions of the API documentation which is up-to-date with the Subversion version of the source code.