Written by the LLVM Team
+This document contains the release notes for the LLVM Compiler -Infrastructure, release 2.5. Here we describe the status of LLVM, including +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 LLVM releases web site.
For more information about LLVM, including information about the latest @@ -51,22 +57,39 @@ current one. To see the release notes for a specific release, please see the releases page.
-The LLVM 2.5 distribution currently consists of code from the core LLVM -repository (which roughly includes the LLVM optimizers, code generators and -supporting tools) and the llvm-gcc repository. In addition to this code, the -LLVM Project includes other sub-projects that are in development. The two which -are the most actively developed are the Clang Project and -the VMKit Project. +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.
The Clang project is an effort to build -a set of new 'LLVM native' front-end technologies for the LLVM optimizer -and code generator. While Clang is not included in the LLVM 2.5 release, it -is continuing to make major strides forward in all areas. Its C and Objective-C -parsing and code generation support is now very solid. For example, it is -capable of successfully building many real applications for X86-32 and X86-64, -including the FreeBSD -kernel. C++ is also making incredible progress, and work -on templates has recently started.
- -While Clang is not yet production quality, it is progressing very nicely and -is quite usable for building many C and Objective-C applications. If you are -interested in fast compiles and good diagnostics, we encourage you to try it out -by building from mainline -and reporting any issues you hit to the Clang front-end mailing -list.
+The Clang project is ...
-In the LLVM 2.5 time-frame, the Clang team has made many improvements:
+In the LLVM 2.7 time-frame, the Clang team has made many improvements:
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 a growing set -of checks to find bugs that occur on a specific path within a program. Examples -of bugs the tool finds include logic errors such as null dereferences, -violations of various API rules, dead code, and potential memory leaks in -Objective-C programs. Since its inception, public feedback on the tool has been -extremely positive, and conservative estimates put the number of real bugs it -has found in industrial-quality software on the order of thousands.
+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 tool also provides a simple web GUI to inspect potential bugs found by -the tool. While still early in development, the GUI illustrates some of the key -features of Clang: accurate source location information, which is used by the -GUI to highlight specific code expressions that relate to a bug (including those -that span multiple lines); and built-in knowledge of macros, which is used to -perform inline expansion of macros within the GUI itself.
- -The set of checks performed by the static analyzer is gradually expanding, -and future plans for the tool include full source-level inter-procedural -analysis and deeper checks such as buffer overrun detection. There are many -opportunities to extend and enhance the static analyzer, and anyone interested -in working on this project is encouraged to get involved!
+In the LLVM 2.7 time-frame, the analyzer core has ...
The VMKit project is an implementation of -a JVM and a CLI Virtual Machines (Microsoft .NET is an -implementation of the CLI) using the Just-In-Time compiler of LLVM.
+a JVM and a CLI Virtual Machine (Microsoft .NET is an +implementation of the CLI) using LLVM for static and just-in-time +compilation. -Following LLVM 2.5, VMKit has its first release ? that you can find on its -webpage. The release includes +
+VMKit version ?? builds with LLVM 2.7 and you can find it on its +web page. The release includes bug fixes, cleanup and new features. The major changes are:
+The new LLVM compiler-rt project +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).
+ ++All of the code in the compiler-rt project is available under the standard LLVM +License, a "BSD-style" license.
+ ++The new LLVM KLEE project 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 algorithms. For more +details, please see the OSDI 2008 paper about +KLEE.
+ ++The goal of DragonEgg is to make +gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever. +DragonEgg is a shared library (dragonegg.so) +that is loaded by gcc at runtime. It ... +
+ ++The LLVM Machine Code (MC) Toolkit project is ... +
+ +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.
+Rubinius 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.
+ +Since LLVM 2.5, Rubinius has made several major leaps forward, implementing +a counter based JIT, type feedback and speculative method inlining. +
+ +-http://pure-lang.googlecode.com/ +MacRuby 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.
-Pure is an algebraic/functional programming language based on term rewriting. +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.
+ ++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), +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.
-In addition to the usual algebraic data structures, Pure also has -MATLAB-style matrices in order to support numeric computations and signal -processing in an efficient way. Pure is mainly aimed at mathematical -applications right now, but it has been designed as a general purpose language. -The dynamic interpreter environment and the C interface make it possible to use -it as a kind of functional scripting language for many application areas. +
Pure versions ??? and later have been tested and are known to work with +LLVM 2.7 (and continue to work with older LLVM releases >= 2.3 as well).
-http://www.dsource.org/projects/ldc +LDC 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.
++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.
+-I'd like to inform that the LDC project (LLVM D -Compiler) is working with release 2.5 of LLVM. In fact we've required -2.5 in our trunk since the release was branched. -The improvements in 2.5 have fixed a lot of problems with LDC, more -specifically the new inline asm constraints, better debug info -support, general bugfixes :) and better x86-64 support have allowed -some major improvements in LDC, getting us much closer to being as -fully featured as the original DMD compiler from DigitalMars. +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-Lua 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.
++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.
This release includes a huge number of bug fixes, performance tweaks, and +
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 2.5 includes several major new capabilities:
+LLVM 2.7 includes several major new capabilities:
The code generator now supports arbitrary precision integers. -Types like i33 have long been valid in the LLVM IR, but previously -could only be used with the interpreter. -Now IR using such types can be compiled to native code on all targets. -All operations are supported if the integer is not bigger than twice the -target machine word size. -Simple operations like loads, stores and shifts by a constant amount are -supported for integers of any size. -
LLVM IR has several new features for better support of new targets and that +expose new optimization opportunities:
+ +LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC -front-ends and driver with the LLVM optimizer and code generator. It currently -includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.
+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:
New features include:
In addition to a huge array of bug fixes and minor performance tweaks, this -release includes a few major enhancements and additions to the optimizers:
+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:
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: +
Things not yet supported:
New target-specific features include: +
New features of the ARM target include:
New features of other targets include: +
+ +New features 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 2.4, this section lists some "gotchas" that you may run into upgrading +on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading from the previous release.
LLVM is known to work on the following platforms:
The core LLVM infrastructure uses GNU autoconf to adapt itself @@ -562,11 +692,26 @@ portability patches and reports of successful builds or error messages.
This section contains significant known problems with the LLVM system, +
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.
+llvm-gcc does not currently support Link-Time -Optimization on most platforms "out-of-the-box". Please inquire on the -LLVMdev mailing list if you are interested.
-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 @@ -778,10 +906,8 @@ itself, Qt, Mozilla, etc.
The Llvm.Linkage module is broken, and has incorrect values. Only +Llvm.Linkage.External, Llvm.Linkage.Available_externally, and +Llvm.Linkage.Link_once will be correct. If you need any of the other linkage +modes, you'll have to write an external C library in order to expose the +functionality. This has been fixed in the trunk.
+