<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.4 Release Notes</title>
+ <title>LLVM 2.5 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.4 Release Notes</div>
+<div class="doc_title">LLVM 2.5 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#subproj">Sub-project Status Update</a></li>
+ <li><a href="#externalproj">External Projects Using LLVM 2.5</a></li>
<li><a href="#whatsnew">What's New in LLVM?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#portability">Portability and Supported Platforms</a></li>
<div class="doc_text">
<p>This document contains the release notes for the LLVM Compiler
-Infrastructure, release 2.4. Here we describe the status of LLVM, including
+Infrastructure, release 2.5. 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 <a
href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
</div>
-<!-- Unfinished features in 2.4:
+<!-- Unfinished features in 2.5:
Machine LICM
Machine Sinking
- LegalizeDAGTypes
+ target-specific intrinsics
+ gold lto plugin
+ pre-alloc splitter, strong phi elim
llc -enable-value-prop, propagation of value info (sign/zero ext info) from
one MBB to another
+ debug info for optimized code
+ interpreter + libffi
+ postalloc scheduler: anti dependence breaking, hazard recognizer?
+
-->
<!-- for announcement email:
- mention dev mtg
- Xcode 3.1 and 3.1.1.
- -->
+ -->
<!-- *********************************************************************** -->
<div class="doc_section">
<div class="doc_text">
<p>
-The LLVM 2.4 distribution currently consists of code from the core LLVM
+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
<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
a set of new 'LLVM native' front-end technologies for the LLVM optimizer
-and code generator. Clang is continuing to make major strides forward in all
-areas. Its C and Objective-C parsing support is very solid, and the code
-generation support is far enough along to build many C applications. While not
-yet production quality, it is progressing very nicely. In addition, C++
-front-end work has started to make significant progress.</p>
-
-<p>Clang, in conjunction with the <tt>ccc</tt> driver, is now usable as a
-replacement for gcc for building some small- to medium-sized C applications.
-Additionally, Clang now has code generation support for Objective-C on Mac OS X
-platform. Major highlights include:</p>
+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 <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">the FreeBSD
+kernel</a>. C++ is also making <a
+href="http://clang.llvm.org/cxx_status.html">incredible progress</a>, and work
+on templates has recently started.</p>
+
+<p>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 <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
+and reporting any issues you hit to the <a
+href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
+list</a>.</p>
+
+<p>In the LLVM 2.5 time-frame, the Clang team has made many improvements:</p>
<ul>
- <li> Clang/ccc pass almost all of the LLVM test suite on Mac OS X and Linux
-on the 32-bit x86 architecture. This includes significant C
-applications such as <a href="http://www.sqlite.org">sqlite3</a>,
-<a href="http://www.lua.org">lua</a>, and
-<a href="http://www.clamav.net">Clam AntiVirus</a>. </li>
-
- <li> Clang can build the majority of Objective-C examples shipped with the
-Mac OS X Developer Tools. </li>
-</ul>
-
-<p>Clang code generation still needs considerable testing and development,
-however. Some areas under active development include:</p>
-
-<ul>
- <li> Improved support for C and Objective-C features, for example
- variable-length arrays, va_arg, exception handling (Obj-C), and garbage
- collection (Obj-C). </li>
- <li> ABI compatibility, especially for platforms other than 32-bit
- x86. </li>
-</ul>
-
+<li>Clang now has a new driver, which is focused on providing a GCC-compatible
+ interface.</li>
+<li>The X86-64 ABI is now supported.</li>
+<li>Precompiled header support is now implemented.</li>
+<li>Objective-C support is significantly improved beyond LLVM 2.4, supporting
+ many features, such as Objective-C Garbage Collection.</li>
+<li>Many many bugs are fixed.</li>
</div>
<!--=========================================================================-->
<div class="doc_text">
-<p>The Clang project also includes an early stage static source code analysis
-tool for <a href="http://clang.llvm.org/StaticAnalysis.html">automatically
-finding bugs</a> 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.</p>
+<p>Previously announced in the last LLVM release, the Clang project also
+includes an early stage static source code analysis tool for <a
+href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
+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.</p>
-<p>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.</p>
+<p>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., <tt>x > 2</tt>)
+between variables and constants.
-<p>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!</p>
+<p>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!</p>
</div>
a JVM and a CLI Virtual Machines (Microsoft .NET is an
implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
-<p>Following LLVM 2.4, VMKit has its first release 0.24 that you can find on its
+<p>Following LLVM 2.5, VMKit has its first release ? that you can find on its
<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
bug fixes, cleanup and new features. The major changes are:</p>
<ul>
-<li> Support for generics in the .Net virtual machine.</li>
-<li> Initial support for the Mono class libraries. </li>
-<li> Support for MacOSX/x86, following LLVM's support for exceptions in
-JIT on MacOSX/x86. </li>
-<li> A new vmkit driver: a program to run java or .net applications. The driver
-supports llvm command line arguments including the new "-fast" option. </li>
-<li> A new memory allocation scheme in the JVM that makes unloading a
-class loader very fast. </li>
-<li> VMKit now follows the LLVM Makefile machinery. </li>
+<li>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.</li>
+
+<li>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%).</li>
+
+<li>New support for OSX/X64, Linux/X64 (with the Boehm GC), Linux/ppc32.</li>
</ul>
</div>
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="externalproj">External Projects Using LLVM 2.5</a>
+</div>
+<!-- *********************************************************************** -->
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="pure">Pure</a>
+</div>
+
+<div class="doc_text">
+<p>
+http://pure-lang.googlecode.com/
+</p>
+
+<p>
+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.</p>
+
+<p>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.
+</p>
+</div>
+
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="ldc">LLVM D Compiler</a>
+</div>
+
+<div class="doc_text">
+<p>
+http://www.dsource.org/projects/ldc
+</p>
+
+<p>
+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.
+</p>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="RoadsendPHP">Roadsend PHP</a>
+</div>
+
+<div class="doc_text">
+<p>http://code.roadsend.com/rphp</p>
+
+<p>Roadsend PHP is using LLVM for code generation. This is an open source
+project.
+</p>
+</div>
+
<!-- *********************************************************************** -->
<div class="doc_section">
<div class="doc_text">
-<p>LLVM 2.4 includes several major new capabilities:</p>
+<p>LLVM 2.5 includes several major new capabilities:</p>
<ul>
-<li><p>The most visible end-user change in LLVM 2.4 is that it includes many
-optimizations and changes to make -O0 compile times much faster. You should see
-improvements in speed on the order of 30% (or more) than in LLVM 2.3. There are
-many pieces to this change described in more detail below. The speedups and new
-components can also be used for JIT compilers that want fast
-compilation.</p></li>
-
-<li><p>The biggest change to the LLVM IR is that Multiple Return Values (which
-were introduced in LLVM 2.3) have been generalized to full support for "First
-Class Aggregate" values in LLVM 2.4. This means that LLVM IR supports using
-structs and arrays as values in a function. This capability is mostly useful
-for front-end authors, who prefer to treat things like complex numbers, simple
-tuples, dope vectors, etc., as Value*'s instead of as a tuple of Value*'s or as
-memory values. Bitcode files from LLVM 2.3 will automatically migrate to the
-general representation.</p></li>
-
-<li><p>LLVM 2.4 also includes an initial port for the PIC16 microprocessor. This
-target only has support for 8 bit registers, and a number of other crazy
-constraints. While the port is still in early development stages, it shows some
-interesting things you can do with LLVM.</p></li>
+<li><p>The code generator now supports arbitrary precision integers.
+Types like <tt>i33</tt> 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.
+</p></li>
+
+<!--
+Random stuff:
+
+Pure project: http://code.google.com/p/pure-lang/
+
+
+xcore backend!
+fortran on darwin!
+
+.ll parser rewrite, caret diags, better errors, less fragile (less likely to
+ crash on strange things). No longer depends on flex/bison.
+GCC inliner off, llvm handles always-inline.
+cmake mature?
+x86 backend GS segment -> addr space 256 (r62980)
+nocapture
+memdep (used by GVN and memcpyopt) is faster / more aggressive.
+how to write a backend doc docs/WritingAnLLVMBackend.html
+fastisel + exception handling
+vector widening <3 x float> -> <4 x float>
+arm port improvements? arm jit encoding stuff, constant island support?
+JIT TLS support on x86-32 but not x86-64.
+mem2reg now faster on code with huge basic blocks
+stack protectors/stack canaries, -fstack-protector, controllable on a
+ per-function basis with attributes.
+shufflevector is generalized to allow different shuffle mask width than its
+ input vectors.
+loop optimizer improves floating point induction variables
+llvm/Analysis/DebugInfo.h classes, llvm-gcc and clang and codegen use them.
+ DebugInfoBuilder gone.
+asmprinters seperate from targets for jits
+PBQP register allocator now supports register coalescing.
+JIT supports exceptions on linux/x86-64 and linux/x86-64.
+integer overflow intrinsics for [us](add/sub/mul). Supported on all targets,
+ but only generates efficient code on x86.
+X86 backend now supports -disable-mmx.
+noalias attribute on return value indicates that function returns new memory
+ (e.g. malloc).
+llvmc2 renamed to llvmc
+Jump threading more powerful: it is iterative, handles threading based on values
+ with fully redundant and partially redundant loads.
+LSR improvements?
+ARM debug info support?
+unit test framework based on Google Test.
+
+vector shift support + X86 backend.
+x86 JIT now detects core i7 and atom, autoconfiguring itself appropriately.
+SROA is more aggressive about promoting unions.
+non-zero __builtin_return_address values on X86.
+x86-64 now uses red zone (unless -mno-red-zone option is specified).
+private linkage.
+
+llvm-gcc defaults to -fno-math-errno on all x86 targets.
+
+initial support for debug line numbers when optimization enabled, not useful in
+ 2.5 but will be for 2.6.
+-->
</ul>
includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
<ul>
-<li>LLVM 2.4 supports the full set of atomic <tt>__sync_*</tt> builtins. LLVM
-2.3 only supported those used by OpenMP, but 2.4 supports them all. Note that
-while llvm-gcc supports all of these builtins, not all targets do. X86 support
-them all in both 32-bit and 64-bit mode and PowerPC supports them all except for
-the 64-bit operations when in 32-bit mode.</li>
-
-<li>llvm-gcc now supports an <tt>-flimited-precision</tt> option, which tells
-the compiler that it is okay to use low-precision approximations of certain libm
-functions (like <tt>exp</tt>, <tt>log</tt>, etc). This allows you to get high
-performance if you only need (say) 12-bits of precision.</li>
-
-<li>llvm-gcc now supports a C language extension known as "<a
-href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks</a>".
-This feature is similar to nested functions and closures, but does not
-require stack trampolines (with most ABIs), and supports returning closures
-from functions that define them. Note that actually <em>using</em> Blocks
-requires a small runtime that is not included with llvm-gcc.</li>
-
-<li>llvm-gcc now supports a new <tt>-flto</tt> option. On systems that support
-transparent Link Time Optimization (currently Darwin systems with Xcode 3.1 and
-later) this allows the use of LTO with other optimization levels like -Os.
-Previously, LTO could only be used with -O4, which implied optimizations in
--O3 that can increase code size.</li>
+<li>?</li>
</ul>
</div>
<p>New features include:</p>
<ul>
-<li>A major change to the <tt>Use</tt> class landed, which shrank it by 25%. Since
-this is a pervasive part of the LLVM, it ended up reducing the memory use of
-LLVM IR in general by 15% for most programs.</li>
-
-<li>Values with no names are now pretty printed by <tt>llvm-dis</tt> more
-nicely. They now print as "<tt>%3 = add i32 %A, 4</tt>" instead of
-"<tt>add i32 %A, 4 ; <i32>:3</tt>", which makes it much easier to read.
-</li>
-
-<li>LLVM 2.4 includes some changes for better vector support. First, the shift
-operations (<tt>shl</tt>, <tt>ashr</tt>, and <tt>lshr</tt>) now all support
-vectors and do an element-by-element shift (shifts of the whole vector can be
-accomplished by bitcasting the vector to <tt><1 x i128></tt>, for example). Second,
-there is initial support in development for vector comparisons with the
-<tt><a href="LangRef.html#i_fcmp">fcmp</a>/<a href="LangRef.html#i_icmp">icmp</a></tt>
-instructions. These instructions compare two vectors and return a vector of
-<tt>i1</tt>'s for each result. Note that there is very little codegen support
-available for any of these IR features though.</li>
-
-<li>A new <tt>DebugInfoBuilder</tt> class is available, which makes it much
-easier for front-ends to create debug info descriptors, similar to the way that
-<tt>IRBuilder</tt> makes it easier to create LLVM IR.</li>
-
-<li>The <tt>IRBuilder</tt> class is now parameterized by a class responsible
-for constant folding. The default <tt>ConstantFolder</tt> class does target independent
-constant folding. The <tt>NoFolder</tt> class does no constant folding at all, which is
-useful when learning how LLVM works. The <tt>TargetFolder</tt> class folds the most,
-doing target dependent constant folding.</li>
-
-<li>LLVM now supports "function attributes", which allow us to separate return
-value attributes from function attributes. LLVM now supports attributes on a
-function itself, a return value, and its parameters. New supported function
-attributes include <tt>noinline/alwaysinline</tt> and the <tt>opt-size</tt> flag,
-which says the function should be optimized for code size.</li>
-
-<li>LLVM IR now directly represents "common" linkage, instead of
- representing it as a form of weak linkage.</li>
+<li>?</li>
</ul>
<ul>
-<li>The Global Value Numbering (GVN) pass now does local Partial Redundancy
-Elimination (PRE) to eliminate some partially redundant expressions in cases
-where doing so won't grow code size.</li>
+<li>?</li>
-<li>LLVM 2.4 includes a new loop deletion pass (which removes output-free
-provably-finite loops) and a rewritten Aggressive Dead Code Elimination (ADCE)
-pass that no longer uses control dependence information. These changes speed up
-the optimizer and also prevent it from deleting output-free infinite
-loops.</li>
+</ul>
-<li>The new AddReadAttrs pass works out which functions are read-only or
-read-none (these correspond to 'pure' and 'const' in GCC) and marks them
-with the appropriate attribute.</li>
+</div>
-<li>LLVM 2.4 now includes a new SparsePropagation framework, which makes it
-trivial to build lattice-based dataflow solvers that operate over LLVM IR. Using
-this interface means that you just define objects to represent your lattice
-values and the transfer functions that operate on them. It handles the
-mechanics of worklist processing, liveness tracking, handling PHI nodes,
-etc.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="codegen">Code Generator Improvements</a>
+</div>
-<li>The Loop Strength Reduction and induction variable optimization passes have
-several improvements to avoid inserting MAX expressions, to optimize simple
-floating point induction variables and to analyze trip counts of more
-loops.</li>
+<div class="doc_text">
-<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
-pulled out of the Instruction Combining pass and put into a new
-<tt>ValueTracking.h</tt> header, where they can be reused by other passes.</li>
+<p>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:</p>
-<li>The tail duplication pass has been removed from the standard optimizer
-sequence used by llvm-gcc. This pass still exists, but the benefits it once
-provided are now achieved by other passes.</li>
+<ul>
+<li>The type legalization logic has been completely rewritten, and is now
+more powerful (it supports arbitrary precision integer types for example)
+and hopefully more correct.
+The type legalizer converts operations on types that are not natively
+supported by the target machine into equivalent code sequences that only use
+natively supported types.
+The old type legalizer is still available and will be used if
+<tt>-disable-legalize-types</tt> is passed to <tt>llc</tt>.
+</li>
+<li>?</li>
</ul>
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="codegen">Code Generator Improvements</a>
+<a name="pic16">PIC16 Target Improvements</a>
</div>
<div class="doc_text">
-
-<p>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:</p>
+<p>New features of the PIC16 target include:
+</p>
<ul>
-<li>The target-independent code generator supports (and the X86 backend
- currently implements) a new interface for "fast" instruction selection. This
- interface is optimized to produce code as quickly as possible, sacrificing
- code quality to do it. This is used by default at -O0 or when using
- "llc -fast" on X86. It is straight-forward to add support for
- other targets if faster -O0 compilation is desired.</li>
-
-<li>In addition to the new 'fast' instruction selection path, many existing
- pieces of the code generator have been optimized in significant ways.
- SelectionDAG's are now pool allocated and use better algorithms in many
- places, the ".s" file printers now use <tt>raw_ostream</tt> to emit text much faster,
- etc. The end result of these improvements is that the compiler also takes
- substantially less time to generate code that is just as good (and often
- better) than before.</li>
-
-<li>Each target has been split to separate the ".s" file printing logic from the
- rest of the target. This enables JIT compilers that don't link in the
- (somewhat large) code and data tables used for printing a ".s" file.</li>
-
-<li>The code generator now includes a "stack slot coloring" pass, which packs
- together individual spilled values into common stack slots. This reduces
- the size of stack frames with many spills, which tends to increase L1 cache
- effectiveness.</li>
-
-<li>Various pieces of the register allocator (e.g. the coalescer and two-address
- operation elimination pass) now know how to rematerialize trivial operations
- to avoid copies and include several other optimizations.</li>
-
-<li>The <a href="CodeGenerator.html#selectiondag_process">graphs</a> produced by
- the <tt>llc -view-*-dags</tt> options are now significantly prettier and
- easier to read.</li>
-
-<li>LLVM 2.4 includes a new register allocator based on Partitioned Boolean
- Quadratic Programming (PBQP). This register allocator is still in
- development, but is very simple and clean.</li>
+<li>Both direct and indirect load/stores work now.</li>
+<li>Logical, bitwise and conditional operations now work for integer data
+types.</li>
+<li>Function calls involving basic types work now.</li>
+<li>Support for integer arrays.</li>
+<li>Compiler can now emit libcalls for operations not support by m/c insns.</li>
+<li>Support for both data and rom address spaces.</li>
+</li>
+</ul>
+
+<p>Things not yet supported:</p>
+<ul>
+<li>Floating point.</li>
+<li>Passing/returning aggregate types to/from functions.</li>
+<li>Variable arguments.</li>
+<li>Indirect function calls.</li>
+<li>Interrupts/prgrams.</li>
+<li>Debug info.</li>
+</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="targetspecific">Target Specific Improvements</a>
+<a name="othertargetspecific">Other Target Specific Improvements</a>
</div>
<div class="doc_text">
</p>
<ul>
-<li>Exception handling is supported by default on Linux/x86-64.</li>
-<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li>
-<li><tt>@llvm.frameaddress</tt> now supports getting the frame address of stack frames
- > 0 on x86/x86-64.</li>
-<li>MIPS has improved a lot since last release, the most important changes
- are: Little endian support, floating point support, allegrex core and
- intrinsics support. O32 ABI is improved but isn't complete. The EABI
- was implemented and is fully supported. We also have support for small
- sections and gp_rel relocation for its access, a threshold in bytes can be
- specified through command line.</li>
-<li>The PowerPC backend now supports trampolines.</li>
+<li>?</li>
+</ul>
+
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="llvmc">Improvements in LLVMC</a>
+</div>
+
+<div class="doc_text">
+<p>New features include:</p>
+
+<ul>
+<li>Beginning with LLVM 2.5, llvmc2 is known as just 'llvmc'. The
+ old llvmc driver was removed.</li>
+
+<li>The Clang plugin was substantially improved and is now enabled
+ by default. The command 'llvmc --clang' can be now used as a
+ synonym to 'ccc'.</li>
+
+<li>There is now a '--check-graph' option which is supposed to
+ catch common errors like multiple default edges, mismatched
+ output/input language names and cycles. In general, these
+ checks can't be done at compile-time because of the need to
+ support plugins.</li>
+
+<li>Plugins are now more flexible and can refer to compilation
+ graph nodes and options defined in other plugins. To manage
+ dependencies, a priority-sorting mechanism was introduced. This
+ change affects the '.td' file syntax; see the documentation for
+ details.</li>
+
+<li>Hooks can now be provided with arguments. The syntax
+ is "$CALL(MyHook, 'Arg1', 'Arg2', 'Arg #3')".</li>
+
+<li>A new option type: multi-valued option, for options that take
+ more than one argument (for example, "-foo a b c").</li>
+
+<li>New option properties: 'one_or_more', 'zero_or_more', 'hidden'
+ and 'really_hidden'.</li>
+
+<li>The 'case' expression gained an 'error' action and an 'empty'
+ test (equivalent to '(not (not_empty ...))').</li>
+
+<li>Documentation now looks more consistent to the rest of the LLVM
+ docs. There is also a man page now.</li>
+
</ul>
</div>
</p>
<ul>
-<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin
- support. It is now easier to experiment with <tt>llvmc2</tt> and
- build your own tools based on it.</li>
-
-<li>LLVM 2.4 includes a number of new generic algorithms and data structures,
- including a scoped hash table, 'immutable' data structures, a simple
- free-list manager, and a <tt>raw_ostream</tt> class.
- The <tt>raw_ostream</tt> class and
- <tt>format</tt> allow for efficient file output, and various pieces of LLVM
- have switched over to use it. The eventual goal is to eliminate
- use of <tt>std::ostream</tt> in favor of it.</li>
-
-<li>LLVM 2.4 includes an optional build system based on CMake. It
- still is in its early stages but can be useful for Visual C++
- users who can not use the Visual Studio IDE.</li>
+<li>?</li>
</ul>
<div class="doc_text">
<p>If you're already an LLVM user or developer with out-of-tree changes based
-on LLVM 2.3, this section lists some "gotchas" that you may run into upgrading
+on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
from the previous release.</p>
<ul>
-<li>The LLVM IR generated by llvm-gcc no longer names all instructions. This
- makes it run faster, but may be more confusing to some people. If you
- prefer to have names, the '<tt>opt -instnamer</tt>' pass will add names to
- all instructions.</li>
-
-<li>The LoadVN and GCSE passes have been removed from the tree. They are
- obsolete and have been replaced with the GVN and MemoryDependence passes.
- </li>
+<li>?</li>
</ul>
API changes are:</p>
<ul>
-
-<li>Now, function attributes and return value attributes are managed
-separately. Interface exported by <tt>ParameterAttributes.h</tt> header is now
-exported by <tt>Attributes.h</tt> header. The new attributes interface changes are:
-<ul>
-<li><tt>getParamAttrs</tt> method is now replaced by
-<tt>getParamAttributes</tt>, <tt>getRetAttributes</tt> and
-<tt>getFnAttributes</tt> methods.</li>
-<li> Return value attributes are stored at index 0. Function attributes are
-stored at index ~0U. Parameter attributes are stored at index that matches
-parameter number.</li>
-<li> <tt>ParamAttr</tt> namespace is now renamed as <tt>Attribute</tt>.</li>
-<li> The name of the class that manages reference count of opaque
-attributes is changed from <tt>PAListPtr</tt> to <tt>AttrListPtr</tt>.</li>
-<li> <tt>ParamAttrsWithIndex</tt> is now renamed as <tt>AttributeWithIndex</tt>.
-</li>
+<li>?</li>
</ul>
-</li>
-<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
-<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
-converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
-"<tt>llvm/Analysis/ValueTracking.h</tt>".</li>
-
-<li>The APIs to create various instructions have changed from lower case
- "create" methods to upper case "Create" methods (e.g.
- <tt>BinaryOperator::create</tt>). LLVM 2.4 includes both cases, but the
- lower case ones are removed in mainline (2.5 and later), please migrate.</li>
-
-<li>Various header files like "<tt>llvm/ADT/iterator</tt>" were given a ".h" suffix.
- Change your code to #include "<tt>llvm/ADT/iterator.h</tt>" instead.</li>
-
-<li>The <tt>getresult</tt> instruction has been removed and replaced with the
- <tt>extractvalue</tt> instruction. This is part of support for first class
- aggregates.</li>
-
-<li>In the code generator, many <tt>MachineOperand</tt> predicates were renamed to be
- shorter (e.g. <tt>isFrameIndex()</tt> -> <tt>isFI()</tt>),
- <tt>SDOperand</tt> was renamed to <tt>SDValue</tt> (and the "<tt>Val</tt>"
- member was changed to be the <tt>getNode()</tt> accessor), and the
- <tt>MVT::ValueType</tt> enum has been replaced with an "<tt>MVT</tt>"
- struct. The <tt>getSignExtended</tt> and <tt>getValue</tt> methods in the
- ConstantSDNode class were renamed to <tt>getSExtValue</tt> and
- <tt>getZExtValue</tt> respectively, to be more consistent with
- the <tt>ConstantInt</tt> class.</li>
+<li>?</li>
</ul>
</div>
C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
C++ code compiled with llc or native compilers.</li>
<li>The C backend does not support all exception handling constructs.</li>
+<li>The C backend does not support arbitrary precision integers.</li>
</ul>
</div>
however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
which does support trampolines.</li>
<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
+This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
+exception handling, which is used internally by the compiler.
Workaround: configure with --disable-bootstrap.</li>
<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
-(c380004 also fails with gcc-4.2 mainline).</li>
+(c380004 also fails with gcc-4.2 mainline).
+If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
+causes the compiler to go into an infinite loop, using up all system memory.</li>
<li>Some gcc specific Ada tests continue to crash the compiler.</li>
<li>The -E binder option (exception backtraces)
<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
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