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
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.
-
-
+
+
+
+ Logo web page.
+ llvm devmtg
+ compiler_rt
+ KLEE web page at klee.llvm.org
+ Many new papers added to /pubs/
+ Mention gcc plugin.
+ -->
@@ -72,12 +105,11 @@ current one. To see the release notes for a specific release, please see the
-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.
@@ -90,34 +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 mainlnie
-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.
+- ...
+include a link to cxx_compatibility.html
+
@@ -127,28 +139,13 @@ list.
-
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.
-
-
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.
+
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 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 sprouted legs and...
@@ -160,33 +157,254 @@ in working on 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:
+
+
+
+
+
+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 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.
+
+
+
+
+
+
+
+Need update.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+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 0.43 and later have been tested and are known to work with
+LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+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.
+
+
+
+
+
+
+
+
+Unladen Swallow is a
+branch of Python intended to be fully
+compatible and significantly faster. It uses LLVM's optimization passes and JIT
+compiler.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-
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.
+
@@ -196,62 +414,148 @@ in this section.
-
LLVM 2.5 includes several major new capabilities:
+
LLVM 2.7 includes several major new capabilities:
+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.
+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 optimization
+New LSR with full strength reduction mode
+The most awesome sext / zext optimization pass. ?
+
+
+
+CondProp pass removed (functionality merged into jump threading).
+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.
+
+
+
+
+
+
+
+
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:
+
Also, -anders-aa was removed
+
-
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:
+
+
+
+
+
+
+
New features of the X86 target include:
+
+
+
@@ -259,55 +563,91 @@ 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:
+
New features of the PIC16 target include:
+
+
+
Things not yet supported:
+
+- Variable arguments.
+- Interrupts/programs.
-
-
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:
+
+
+
Major Changes and Removed Features
@@ -316,12 +656,15 @@ faster:
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.
-
-- ?
+- 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.
+
@@ -329,10 +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.
@@ -350,16 +717,16 @@ API changes are:
LLVM is known to work on the following platforms:
-- 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 (IA32, X86-64, AMD64, EMT-64) running Red Hat
+ Linux, Fedora Core, FreeBSD and AuroraUX (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
@@ -377,11 +744,20 @@ 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 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.
+
+
@@ -399,9 +775,11 @@ components, please contact us on the
LLVMdev list.
-- The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.
-- The llc "-filetype=asm" (the default) is the only supported
- value for this option.
+- The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
+ backends are experimental.
+- The llc "-filetype=asm" (the default) is the only
+ supported value for this option. The MachO writer is experimental, and
+ works much better in mainline SVN.
@@ -421,13 +799,14 @@ href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list.
The X86 backend generates inefficient floating point code when configured
to generate code for systems that don't have SSE2.
Win64 code generation wasn't widely tested. Everything should work, but we
- expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
- currently due
+ expect small issues to happen. Also, llvm-gcc cannot build the mingw64
+ runtime currently due
to several
- bugs due to lack of support for the
- 'u' inline assembly constraint and X87 floating point inline assembly.
+
bugs and due to lack of support for
+ the
+ 'u' inline assembly constraint and for X87 floating point inline assembly.
The X86-64 backend does not yet support the LLVM IR instruction
- va_arg. Currently, the llvm-gcc front-end supports variadic
+ va_arg. Currently, the llvm-gcc and front-ends support variadic
argument constructs on X86-64 by lowering them manually.
@@ -455,14 +834,14 @@ compilation, and lacks support for debug information.
+- 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.
- Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
processors, thumb programs can crash or produce wrong
results (PR1388).
-- Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
+
- Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
-- There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly
- execute
-programs compiled with LLVM. Please use more recent versions of QEMU.
@@ -475,7 +854,7 @@ programs compiled with LLVM. Please use more recent versions of QEMU.
-- 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).
@@ -489,7 +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.
@@ -510,21 +888,6 @@ appropriate nops inserted to ensure restartability.
-
-
-
-
-
-
-- 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
@@ -537,8 +900,9 @@ 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.
@@ -546,15 +910,11 @@ appropriate nops inserted to ensure restartability.
-
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
@@ -566,24 +926,6 @@ LLVMdev mailing list if you are interested.
-
-
-
-
-
-
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
@@ -592,10 +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.
+ in Bugzilla. Please see the
+ tools/gfortran component for details.
@@ -605,22 +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.
-Workaround: configure with --disable-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.
- The c380004, c393010
and cxg2021 ACATS tests fail
-(c380004 also fails with gcc-4.2 mainline).
-- Some gcc specific Ada tests continue to crash the compiler.
-- The -E binder option (exception backtraces)
+(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)
does not work and will result in programs
-crashing if an exception is raised. Workaround: do not use -E.
+crashing if an exception is raised. Workaround: do not use -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
@@ -634,6 +978,20 @@ ignored.
+
+
+
+
+
+
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.
+
+
