LLVM 2.5 Release Notes

Introduction @@ -34,7 +43,7 @@

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.

@@ -42,34 +51,50 @@ href="http://llvm.org/releases/">LLVM releases web site.

For more information about LLVM, including information about the latest release, please check out the main LLVM web site. If you have questions or comments, the LLVM Developer's Mailing -List is a good place to send them.

+href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's +Mailing List is a good place to send them.

Note that if you are reading this file from a Subversion checkout or the 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.

- + + + @@ -80,12 +105,11 @@ initial support for debug line numbers when optimization enabled, not useful in

-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.

@@ -98,35 +122,14 @@ the VMKit Project.

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:

Clang now has a new driver, which is focused on providing a GCC-compatible - interface.
The X86-64 ABI is now supported.
Precompiled header support is now implemented.
Objective-C support is significantly improved beyond LLVM 2.4, supporting - many features, such as Objective-C Garbage Collection.
Many many bugs are fixed and many features have been added.
...

@@ -136,25 +139,13 @@ list.

Previously announced in the last LLVM release, the Clang project also +

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 a growing set of checks to find +in C and Objective-C programs. The tool performs checks to find bugs that occur on a specific path within a program.

In the LLVM 2.5 time-frame there have been many significant improvements to -the analyzer's core path simulation engine and machinery for generating -path-based bug reports to end-users. Particularly noteworthy improvements -include experimental support for full field-sensitivity and reasoning about heap -objects as well as an improved value-constraints subengine that does a much -better job of reasoning about inequality relationships (e.g., x > 2) -between variables and constants. - -

The set of checks performed by the static analyzer continue to expand, 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 sprouted legs and...

@@ -166,38 +157,134 @@ this project is encouraged to get involved!

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:

Ahead of Time compiler: compiles .class files to llvm .bc. VMKit uses this -functionality to native compile the standard classes (eg java.lang.String). -Users can compile AOT .class files into dynamic libraries and run them with the -help of VMKit.
...
New exception model: the dwarf exception model is very slow for -exception-intensive applications, so the JVM has had a new implementation of -exceptions which check at each function call if an exception happened. There is -a low performance penalty on applications without exceptions, but it is a big -gain for exception-intensive applications. For example the jack benchmark in -Spec JVM98 is 6x faster (performance gain of 83%).

New support for OSX/X64, Linux/X64 (with the Boehm GC), Linux/ppc32.

- + +

+compiler-rt: Compiler Runtime Library +

+ +

+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.

+ +

+DragonEgg: GCC-4.5 as an LLVM frontend +

+ +

+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 ... +

+ +

+ + + +

+llvm-mc: Machine Code Toolkit +

+ +

+The LLVM Machine Code (MC) Toolkit project is ... +

+ +

- External Projects Using LLVM 2.5 + External Open Source Projects Using LLVM 2.7

+ +

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 +

+ +

+Need update. + +

+ +

+ + +

+MacRuby +

+ +

+Need update. +

+ +

Pure @@ -214,13 +301,9 @@ 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 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).

@@ -231,13 +314,16 @@ it as a kind of functional scripting language for many application areas.

+Need update. +

@@ -247,89 +333,142 @@ fully featured as the original DMD compiler from DigitalMars.

- What's New in LLVM 2.5? + +

+Unladen Swallow

- -

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. +

+Unladen Swallow is a +branch of Python intended to be fully +compatible and significantly faster. It uses LLVM's optimization passes and JIT +compiler.

-Major New Features +llvm-lua

+Need update. + +

LLVM 2.5 includes several major new capabilities:

+ +

+IcedTea Java Virtual Machine Implementation +

LLVM 2.5 includes a brand new XCore backend.

+Need update. + +

llvm-gcc now generally supports the GFortan front-end, and the precompiled -release binaries now support Fortran, even on Mac OS/X.
CMake is now used by the LLVM build process -on Windows. It automatically generates Visual Studio project files (and -more) from a set of simple text files. This makes it much easier to -maintain. In time, we'd like to standardize on CMake for everything.
LLVM 2.5 now uses (and includes) Google Test for unit testing.

+ What's New in LLVM 2.7? +

The LLVM native code generator now supports arbitrary precision integers. -Types like i33 have long been valid in the LLVM IR, but were previously -only supported by the interpreter. Note that the C backend still does not -support these.

LLVM 2.5 no longer uses 'bison', so it is easier to build on Windows.

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 IR has several new features that are used by our existing front-ends and -can be useful if you are writing a front-end for LLVM:

LLVM IR has several new features for better support of new targets and that +expose new optimization opportunities:

The shufflevector instruction -has been generalized to allow different shuffle mask width than its input -vectors. This allows you to use shufflevector to combine two -"<4 x float>" vectors into a "<8 x float>" for example.
LLVM IR now supports new intrinsics for computing and acting on overflow of integer operations. This allows -efficient code generation for languages that must trap or throw an exception on -overflow. While these intrinsics work on all targets, they only generate -efficient code on X86 so far.
LLVM IR now supports a new private -linkage type to produce labels that are stripped by the assembler before it -produces a .o file (thus they are invisible to the linker).
LLVM IR supports two new attributes for better alias analysis. The noalias attribute can now be used on the -return value of a function to indicate that it returns new memory (e.g. -'malloc', 'calloc', etc).
The new nocapture attribute can be -used on pointer arguments to functions that access through but do not return the -pointer in a data structure that out lives the call (e.g. 'strlen', 'memcpy', -and many others). The simplifylibcalls pass applies these attributes to -standard libc functions.
The parser for ".ll" files in lib/AsmParser is now completely rewritten as a -recursive descent parser. This parser produces better error messages (including -caret diagnostics) is less fragile (less likely to crash on strange things) does -not leak memory, is more efficient, and eliminates LLVM's last use of the -'bison' tool.
Debug information representation and manipulation internals have been - consolidated to use a new set of classes in - llvm/Analysis/DebugInfo.h classes. These routines are more - efficient, robust, and extensible and replace the older mechanisms. - llvm-gcc, clang, and the code generator now use them to create and process - debug information.
...

Major Changes and Removed Features @@ -595,12 +656,15 @@ types.

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-gcc defaults to -fno-math-errno on all x86 targets.
The LLVM interpreter now defaults to not using libffi 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 libffi, +configure with --enable-libffi. +

@@ -608,10 +672,34 @@ from the previous release.

API changes are:

- -

ModuleProvider has been removed +and its methods moved to Module and GlobalValue. +Most clients can remove uses of ExistingModuleProvider, +replace getBitcodeModuleProvider with +getLazyBitcodeModule, and pass their Module to +functions that used to accept ModuleProvider. Clients who +wrote their own ModuleProviders will need to derive from +GVMaterializer instead and use +Module::setMaterializer to attach it to a +Module.

+ +

GhostLinkage has given up the ghost. +GlobalValues 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 +GlobalValue::hasNotBeenReadFromBitcode with +GlobalValue::isMaterializable.

+ +

FIXME: Debug info has been totally redone. Add pointers to new APIs. Substantial caveats about compatibility of .ll and .bc files.

+ +

The llvm/Support/DataTypes.h header has moved +to llvm/System/DataTypes.h.

+ +

The isInteger, isIntOrIntVector, isFloatingPoint, +isFPOrFPVector and isFPOrFPVector methods have been renamed +isIntegerTy, isIntOrIntVectorTy, isFloatingPointTy, +isFPOrFPVectorTy and isFPOrFPVectorTy respectively.

@@ -630,15 +718,15 @@ API changes are:

Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat -Linux, Fedora Core and FreeBSD (and probably other unix-like systems).
PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit -and 64-bit modes.
Intel and AMD machines running on Win32 using MinGW libraries (native).
Intel and AMD machines running on Win32 with the Cygwin libraries (limited support is available for native builds with Visual C++).
Sun UltraSPARC workstations running Solaris 10.
Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.
Alpha-based machines running Debian GNU/Linux.
Itanium-based (IA64) machines running Linux and HP-UX.

The core LLVM infrastructure uses GNU autoconf to adapt itself @@ -661,6 +749,15 @@ 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 will not correctly compile on Solaris and/or OpenSolaris +using the stock GCC 3.x.x series 'out the box', +See: Broken versions of GCC and other tools. +However, A Modern GCC Build +for x86/x86-64 has been made available from the third party AuroraUX Project +that has been meticulously tested for bootstrapping LLVM & Clang.

The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not +
The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not support the 64-bit SPARC ABI (-m64).

@@ -768,7 +868,6 @@ programs compiled with LLVM. Please use more recent versions of QEMU.

The O32 ABI is not fully supported.
64-bit MIPS targets are not supported yet.

@@ -789,21 +888,6 @@ appropriate nops inserted to ensure restartability.

- -

- Known problems with the IA64 back-end -

- -

The Itanium backend is highly experimental, and has a number of known - issues. We are looking for a maintainer for the Itanium backend. If you - are interested, please contact the LLVMdev mailing list.

- -

Known problems with the C back-end @@ -816,7 +900,7 @@ appropriate nops inserted to ensure restartability. inline assembly code.

The C backend violates the ABI of common C++ programs, preventing intermixing between C++ compiled by the CBE and - C++ code compiled with llc or native compilers.

+ C++ code compiled with llc or native compilers.

The C backend does not support all exception handling constructs.

The C backend does not support arbitrary precision integers.

@@ -826,15 +910,11 @@ appropriate nops inserted to ensure restartability.

- Known problems with the llvm-gcc C front-end + Known problems with the llvm-gcc C and C++ front-end

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 @@ -846,24 +926,6 @@ LLVMdev mailing list if you are interested.

- -

- Known problems with the llvm-gcc C++ front-end -

- -

The C++ front-end is considered to be fully -tested and works for a number of non-trivial programs, including LLVM -itself, Qt, Mozilla, etc.

- -

Exception handling works well on the X86 and PowerPC targets. Currently - only Linux and Darwin targets are supported (both 32 and 64 bit).

- -

Known problems with the llvm-gcc Fortran front-end @@ -872,10 +934,8 @@ itself, Qt, Mozilla, etc.

Fortran support generally works, but there are still several unresolved bugs - in Bugzilla. Please see the tools/gfortran component for details.
The Fortran front-end currently does not build on Darwin (without tweaks) - due to unresolved dependencies on the C front-end.

Bugzilla

@@ -885,26 +945,26 @@ itself, Qt, Mozilla, etc.

-The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature -technology and problems should be expected. +The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature +technology, and problems should be expected.

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 also fails to build on X86-64 +to lack of trampoline support (pointers to nested functions) on other platforms. +However, it also fails to build on X86-64 which does support trampolines.
The Ada front-end fails to bootstrap. This is due to lack of LLVM support for setjmp/longjmp style exception handling, which is used internally by the compiler. -Workaround: configure with --disable-bootstrap.

--disable-bootstrap

The c380004, c393010 and cxg2021 ACATS tests fail (c380004 also fails with gcc-4.2 mainline). If the compiler is built with checks disabled then c393010 causes the compiler to go into an infinite loop, using up all system memory.
Some gcc specific Ada tests continue to crash the compiler.
The -E binder option (exception backtraces) +
Some GCC specific Ada tests continue to crash the compiler.
The -E binder option (exception backtraces) does not work and will result in programs -crashing if an exception is raised. Workaround: do not use -E.

-E

Only discrete types are allowed to start or finish at a non-byte offset in a record. Workaround: do not pack records or use representation clauses that result in a field of a non-discrete type @@ -918,6 +978,20 @@ ignored.

+ +

+ Known problems with the O'Caml bindings +

+ +

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.

Additional Information

These are in-progress notes for the upcoming LLVM 2.7 +release. +You may prefer the +LLVM 2.6 +Release Notes.

These are in-progress notes for the upcoming LLVM 2.7 +release.
+You may prefer the +LLVM 2.6 +Release Notes.