+
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.2 Release Notes</title>
+ <title>LLVM 2.3 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.2 Release Notes</div>
+<div class="doc_title">LLVM 2.3 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</a></li>
+ <li><a href="#changes">Major Changes and Sub-project Status</a></li>
<li><a href="#whatsnew">What's New?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#portability">Portability and Supported Platforms</a></li>
<p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
</div>
+<!-- Done through Week-of-Mon-20080324.txt -->
<!-- *********************************************************************** -->
<div class="doc_section">
<div class="doc_text">
<p>This document contains the release notes for the LLVM compiler
-infrastructure, release 2.2. Here we describe the status of LLVM, including
+infrastructure, release 2.3. Here we describe the status of LLVM, including
major improvements from the previous release and any known problems. All LLVM
releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
releases web site</a>.</p>
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="whatsnew">What's New?</a>
+ <a name="changes">Major Changes and Sub-project Status</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
-<p>This is the thirteenth public release of the LLVM Compiler Infrastructure.
-It includes many features and refinements from LLVM 2.1.</p>
+<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
+It includes a large number of features and refinements from LLVM 2.2.</p>
</div>
-<!-- Unfinished features in 2.2:
- Index Set Splitting not enabled by default
+<!-- Unfinished features in 2.3:
Machine LICM
Machine Sinking
LegalizeDAGTypes
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="deprecation">Deprecated features in LLVM 2.2</a>
+<a name="changes">Major Changes in LLVM 2.3</a>
</div>
<div class="doc_text">
-<p>This is the last LLVM release to support llvm-gcc 4.0, llvm-upgrade, and
-llvmc in its current form. llvm-gcc 4.0 has been replaced with llvm-gcc 4.2.
-llvm-upgrade is useful for upgrading llvm 1.9 files to llvm 2.x syntax, but you
-can always use an old release to do this. llvmc is currently mostly useless in
-llvm 2.2, and will be redesigned or removed in llvm 2.3.</p>
+<p>LLVM 2.3 no longer supports llvm-gcc 4.0, it has been replaced with
+ llvm-gcc 4.2.</p>
+
+<p>LLVM 2.3 no longer includes the <tt>llvm-upgrade</tt> tool. It was useful
+ for upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a
+ previous LLVM release to do this. One nice impact of this is that the LLVM
+ regression test suite no longer depends on llvm-upgrade, which makes it run
+ faster.</p>
+<p>The <tt>llvm2cpp</tt> tool has been folded into llc, use
+ <tt>llc -march=cpp</tt> instead of <tt>llvm2cpp</tt>.</p>
+
+<p>LLVM API Changes:</p>
+
+<ul>
+<li>Several core LLVM IR classes have migrated to use the
+ '<tt>FOOCLASS::Create(...)</tt>' pattern instead of '<tt>new
+ FOOCLASS(...)</tt>' (e.g. where FOOCLASS=<tt>BasicBlock</tt>). We hope to
+ standardize on <tt>FOOCLASS::Create</tt> for all IR classes in the future,
+ but not all of them have been moved over yet.</li>
+<li>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
+ IRBuilder.</li>
+<li>MRegisterInfo was renamed to TargetRegisterInfo.</li>
+<li>The MappedFile class is gone, please use MemoryBuffer instead.</li>
+<li>The '<tt>-enable-eh</tt>' flag to llc has been removed. Now code should
+ encode whether it is safe to omit unwind information for a function by
+ tagging the Function object with the '<tt>nounwind</tt>' attribute.</li>
+
+</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
+<a name="otherprojects">Other LLVM Sub-Projects</a>
+</div>
+
+<div class="doc_text">
+<p>
+The core LLVM 2.3 distribution currently consists of code from the core LLVM
+repository (which roughly contains the LLVM optimizer, 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 new <a href="#vmkit">vmkit Project</a>
+and the <a href="#clang">Clang Project</a>.
+</p>
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsubsection">
+<a name="vmkit">vmkit</a>
+</div>
+
+<div class="doc_text">
+<p>
+The "vmkit" project is a new addition to the LLVM family. It 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.</p>
+
+<p>The JVM, called JnJVM, executes real-world applications such as Apache
+projects (e.g. Felix and Tomcat) and the SpecJVM98 benchmark. It uses the GNU
+Classpath project for the base classes. The CLI implementation, called N3, is
+its in early stages but can execute simple applications and the "pnetmark"
+benchmark. It uses the pnetlib project as its core library.</p>
+
+<p>The 'vmkit' VMs compare in performance with industrial and top open-source
+VMs on scientific applications. Besides the JIT, the VMs use many features of
+the LLVM framework, including the standard set of optimizations, atomic
+operations, custom function provider and memory manager for JITed methods, and
+specific virtual machine optimizations. vmkit is not an official part of LLVM
+2.3 release. It is publicly available under the LLVM license and can be
+downloaded from:
+</p>
+
+<p>
+<tt>svn co http://llvm.org/svn/llvm-project/vmkit/trunk vmkit</tt>
+</p>
+
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsubsection">
+<a name="clang">Clang</a>
</div>
<div class="doc_text">
-<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
-LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
-has made leaps and bounds and is now at least as good as 4.0 in virtually every
-area, and is better in several areas (for example, exception handling
-correctness, support for Ada and Fortran, better ABI compatibility, etc). We
-strongly recommend that you
-migrate from llvm-gcc 4.0 to llvm-gcc 4.2 in this release cycle because
-<b>LLVM 2.2 is the last release that will support llvm-gcc 4.0</b>: LLVM 2.3
-will only support the llvm-gcc 4.2 front-end.</p>
+<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>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. Currently, its C and Objective-C support is maturing
-nicely, and it has advanced source-to-source analysis and transformation
-capabilities. If you are interested in building source-level tools for C and
-Objective-C (and eventually C++), you should take a look. However, note that
-clang is not an official part of the LLVM 2.2 release. If you are interested in
-this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
+<p>At this point, Clang is most useful if you are interested in source-to-source
+transformations (such as refactoring) and other source-level tools for C and
+Objective-C. Clang now also includes tools for turning C code into pretty HTML,
+and includes a new <a href="http://clang.llvm.org/StaticAnalysis.html">static
+analysis tool</a> in development. This tool is automatically focused on finding
+bugs in C and Objective-C code.</p>
</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="whatsnew">What's New?</a>
+</div>
+<!-- *********************************************************************** -->
+
<!--=========================================================================-->
<div class="doc_subsection">
<a name="majorfeatures">Major New Features</a>
<div class="doc_text">
-<p>LLVM 2.2 includes several major new capabilities:</p>
+<p>LLVM 2.3 includes several major new capabilities:</p>
<ul>
-<li>Scott Michel contributed an SPU backend, which generates code for the
-vector coprocessors on the Cell processor. (Status?)</li>
+<li><p>The biggest change in LLVM 2.3 is Multiple Return Value (MRV) support.
+ MRVs allow LLVM IR to directly represent functions that return multiple
+ values without having to pass them "by reference" in the LLVM IR. This
+ allows a front-end to generate more efficient code, as MRVs are generally
+ returned in registers if a target supports them. See the <a
+ href="LangRef.html#i_getresult">LLVM IR Reference</a> for more details.</p>
+
+ <p>MRVs are fully supported in the LLVM IR, but are not yet fully supported in
+ on all targets. However, it is generally safe to return up to 2 values from
+ a function: most targets should be able to handle at least that. MRV
+ support is a critical requirement for X86-64 ABI support, as X86-64 requires
+ the ability to return multiple registers from functions, and we use MRVs to
+ accomplish this in a direct way.</p></li>
+
+<li><p>LLVM 2.3 includes a complete reimplementation of the "<tt>llvmc</tt>"
+ tool. It is designed to overcome several problems with the original
+ <tt>llvmc</tt> and to provide a superset of the features of the
+ '<tt>gcc</tt>' driver.</p>
+
+<p>The main features of <tt>llvmc2</tt> are:
+ <ul>
+ <li>Extended handling of command line options and smart rules for
+ dispatching them to different tools.</li>
+ <li>Flexible (and extensible) rules for defining different tools.</li>
+ <li>The different intermediate steps performed by tools are represented
+ as edges in the abstract graph.</li>
+ <li>The 'language' for driver behavior definition is tablegen and thus
+ it's relatively easy to add new features.</li>
+ <li>The definition of driver is transformed into set of C++ classes, thus
+ no runtime interpretation is needed.</li>
+ </ul></p>
+ </li>
+
+<li><p>LLVM 2.3 includes a completely rewritten interface for <a
+ href="LinkTimeOptimization.html">Link Time Optimization</a>. This interface
+ is written in C, which allows for easier integration with C code bases, and
+ incorporates improvements we learned about from the first incarnation of the
+ interface.</p></li>
+
+<li><p>The <a href="tutorial/LangImpl1.html">Kaleidoscope tutorial</a> now
+ includes a "port" of the tutorial that <a
+ href="tutorial/OCamlLangImpl1.html">uses the Ocaml bindings</a> to implement
+ the Kaleidoscope language.</p></li>
-<li>Anton and Duncan significantly improved llvm-gcc 4.2 support for the GCC Ada
-(GNAT) and Fortran (gfortran) front-ends. These front-ends should still be considered
-experimental however: see the <a href="#knownproblems">list of known problems</a>.
-The release binaries do not contain either front-end: they need to be built from
-source (the Ada front-end only builds on x86-32 linux).</li>
+</ul>
-<li>Dale contributed full support for long double on x86/x86-64 (where it is 80
-bits) and on Darwin PPC/PPC64 (where it is 128 bits). In previous LLVM
-releases, llvm-gcc silently mapped long double to double.</li>
+</div>
-<li>Gordon Henriksen rewrote most of the <a href="GarbageCollection.html"
->Accurate Garbage Collection</a> code in the code generator, making the
-generated code more efficient and adding support for the OCaml garbage collector
-metadata format.</li>
-<li>Christopher Lamb contributed support for multiple address spaces in LLVM
-IR. This is useful for supporting targets that have 'near' vs 'far' pointers,
-'RAM' vs 'ROM' pointers, or that have non-local memory that can be accessed with
-special instructions.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
+</div>
-<li>LLVM now includes a new set of detailed <a
-href="tutorial/index.html">tutorials</a>, which explain how to implement a
-language with LLVM and shows how to use several important APIs.</li>
+<div class="doc_text">
-</ul>
+<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end.</p>
+
+<p>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
+front-end. Objective-C now works very well on Mac OS/X.</p>
+
+<p>Fortran EQUIVALENCEs are now supported by the gfortran front-end.</p>
+
+<p>llvm-gcc 4.2 includes many other fixes which improve conformance with the
+relevant parts of the GCC testsuite.</p>
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
<a name="coreimprovements">LLVM Core Improvements</a>
<p>New features include:
</p>
-<ul>
-<li>Gordon contributed support for C and OCaml Bindings for the basic LLVM IR
-construction routines as well as several other auxiliary APIs.</li>
-
-<li>Anton added readnone/readonly attributes for modeling function side effects.
-Duncan hooked up GCC's pure/const attributes to them and enhanced mod/ref
-analysis to use them.</li>
-
-<li>Devang added LLVMFoldingBuilder, a version of LLVMBuilder that implicitly
-simplifies the code as it is constructed.</li>
-<li>Ted Kremenek added a framework for generic object serialization to bitcode
-files. This support is only used by clang right now for ASTs but is extensible
-and could be used for serializing arbitrary other data into bitcode files.</li>
-
-<li>Duncan improved TargetData to distinguish between the size/alignment of a
-type in a register, in memory according to the platform ABI, and in memory when
-we have a choice.</li>
+Common linkage?
-<li>Reid moved parameter attributes off of FunctionType and onto functions
-and calls. This makes it much easier to add attributes to a function in a
-transformation pass.</li>
-
-<li>Dan Gohman added support for vector sin, cos, and pow intrinsics.</li>
+Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize",
+"__sync_val_compare_and_swap", etc
+<ul>
+<li>The C and Ocaml bindings have received additional improvements. The
+bindings now cover pass managers, several transformation passes, iteration
+over the LLVM IR, target data, and parameter attribute lists.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="codegen">Code Generator Improvements</a>
+<a name="optimizer">Optimizer Improvements</a>
</div>
<div class="doc_text">
-<p>We 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>In addition to a huge array of bug fixes and minor performance tweaks, the
+LLVM 2.3 optimizers support a few major enhancements:</p>
<ul>
-<li>Owen refactored the existing LLVM dominator and loop information code to
-allow it work on the machine code representation. He contributed support for
-dominator and loop information on machine code and merged the code for forward
-and backward dominator computation.</li>
+<li>Loop index set splitting on by default.<p>
+This transformation hoists conditions from loop bodies and reduces loop's
+iteration space to improve performance. For example, <p>
+<pre>
+for (i = LB; i < UB; ++i)
+ if (i <= NV)
+ LOOP_BODY
+</pre>
+is transformed into
+<pre>
+NUB = min(NV+1, UB)
+for (i = LB; i < NUB; ++i)
+ LOOP_BODY
+</pre>
+</li>
-<li>Dan added support for emitting debug information with .file and .loc
-directives on platforms that support it, instead of emitting large tables in the .s
-file.</li>
+<li>LLVM includes a new <tt>memcpy</tt> optimization pass which removes
+dead <tt>memcpy</tt> calls, unneeded copies of aggregates, and performs
+return slot optimization. The LLVM optimizer now notices long sequences of
+consecutive stores and merges them into <tt>memcpy</tt>'s where profitable.</li>
-<li>Evan extended the DAG scheduler to model physical register dependencies
-explicitly and have the BURR scheduler pick a correct schedule based on the
-dependencies. This reduces our use of the 'flag' operand hack.</li>
+<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
+<tt>memset</tt> is now more aggressive.</li>
-<li>Evan added initial support for register coalescing of subregister
-references.</li>
+<li>The aggressive dead code elimination (ADCE) optimization has been rewritten
+to make it both faster and safer in the presence of code containing infinite
+loops. Some of its prior functionality has been factored out into the loop
+deletion pass, which <em>is</em> safe for infinite loops.</li>
-<li>Rafael Espindola implemented initial support for a new 'byval' attribute,
-which allows more efficient by-value argument passing in the LLVM IR. Evan
-finished support for it and enabled it in the X86 (32- and 64-bit) and C
-backends.</li>
+<li>Several optimizations have been sped up, leading to faster code generation
+ with the same code quality.</li>
+
+<li>The 'SimplifyLibCalls' pass, which optimizes calls to libc and libm
+ functions for C-based languages, has been rewritten to be a FunctionPass
+ instead a ModulePass. This allows it to be run more often and to be
+ included at -O1 in llvm-gcc. It was also extended to include more
+ optimizations and several corner case bugs were fixed.</li>
+
+<li>LLVM now includes a simple 'Jump Threading' pass, which attempts to simplify
+ conditional branches using information about predecessor blocks, simplifying
+ the control flow graph. This pass is pretty basic at this point, but
+ catches some important cases and provides a foundation to build on.</li>
+
+<li>Several corner case bugs which could lead to deleting volatile memory
+ accesses have been fixed.</li>
+</ul>
-<li>The LLVM TargetInstrInfo class can now answer queries about the mod/ref and
-side-effect behavior of MachineInstr's. This information is inferred
-automatically by TableGen from .td files for all instructions with
-patterns.</li>
+</div>
-<li>Evan implemented simple live interval splitting on basic block boundaries.
-This allows the register allocator to be more successful at keeping values in
-registers in some parts of a value's live range, even if they need to be spilled
-in some other block.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="codegen">Code Generator Improvements</a>
+</div>
+
+<div class="doc_text">
-<li>The new MachineRegisterInfo.h class provides support for efficiently
-iterating over all defs/uses of a register, and this information is
-automatically kept up-to-date. This support is similar to the use_iterator in
-the LLVM IR level.</li>
+<p>We 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 MachineInstr, MachineOperand and TargetInstrDesc classes are simpler,
-more consistent, and better documented.</li>
+<ul>
+<li>MemOperand in the code generator: describe me!.</li>
+
+<li>The target-independent code generator infrastructure now uses LLVM's APInt
+ class to handle integer values, which allows it to support integer types
+ larger than 64 bits. Note that support for such types is also dependent on
+ target-specific support. Use of APInt is also a step toward support for
+ non-power-of-2 integer sizes.</li>
+
+<li>LLVM 2.3 includes several compile time speedups for code with large basic
+ blocks, particular in the instruction selection phase, register allocation,
+ scheduling, and tail merging/jump threading.</li>
+
+<li>Several improvements which make llc's <tt>--view-sunit-dags</tt>
+ visualization of scheduling dependency graphs easier to understand.</li>
+
+<li>The code generator allows targets to write patterns that generate subreg
+ references directly in .td files now.</li>
+
+<li><tt>memcpy</tt> lowering in the backend is more aggressive, particularly for
+ <tt>memcpy</tt> calls introduced by the code generator when handling
+ pass-by-value structure argument copies.</li>
+
+<li>Inline assembly with multiple register results now returns those results
+ directly in the appropriate registers, rather than going through memory.
+ Inline assembly that uses constraints like "ir" with immediates now use the
+ 'i' form when possible instead of always loading the value in a register.
+ This saves an instruction and reduces register use.</li>
+
+<li>Added support for PIC/GOT style tail calls on x86/32 and initial support
+ for tail calls on PowerPC 32 (it may also work on ppc64 but not
+ thoroughly tested).</li>
</ul>
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="optimizer">Optimizer Improvements</a>
+<a name="x86specific">X86/X86-64 Specific Improvements</a>
</div>
<div class="doc_text">
-
-<p>In addition to a huge array of bug fixes and minor performance tweaks, the
-LLVM 2.2 optimizers support a few major enhancements:</p>
+<p>New target-specific features include:
+</p>
<ul>
+<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
+ area of passing and returning structures by value. llvm-gcc compiled code
+ now interoperates very well on X86-64 systems with other compilers.</li>
-<li>Daniel Berlin and Curtis Dunham rewrote Andersen's alias analysis to be
-several orders of magnitude faster, and implemented Offline Variable
-Substitution and Lazy Cycle Detection. Note that Andersen's is not enabled in
-llvm-gcc by default, but can be accessed through 'opt'.</li>
+<li>Support for Win64 was added. This includes code generation itself, JIT
+ support and necessary changes to llvm-gcc.</li>
-<li>Dan Gohman contributed several enhancements to Loop Strength Reduction (LSR)
-to make it more aggressive with SSE intrinsics and when induction variables are
-used by non-memory instructions.</li>
+<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
+ the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins. Various
+ generic vector operations (insert/extract/shuffle) are much more efficient
+ when SSE 4.1 is enabled. The JIT automatically takes advantage of these
+ instructions, but llvm-gcc must be explicitly told to use them, e.g. with
+ <tt>-march=penryn</tt>.</li>
-<li>Evan added support for simple exit value substitution to LSR.</li>
+<li>The X86 backend now does a number of optimizations that aim to avoid
+ converting numbers back and forth from SSE registers to the X87 floating
+ point stack.</li>
-<li>Evan enhanced LSR to support induction variable reuse when the induction
-variables have different widths.</li>
+<li>The X86 backend supports stack realignment, which is particularly useful for
+ vector code on OS's without 16-byte aligned stacks.</li>
-</ul>
+<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
+ functions to be tagged as passing floating point values in SSE
+ registers.</li>
-</div>
+<li>Trampolines (taking the address of a nested function) now work on
+ Linux/X86-64.</li>
+<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
+ instructions instead of being ignored.</li>
+
+<li>128-bit integers are now supported on X86-64 targets.</li>
+
+<li>The register allocator can now rematerialize PIC-base computations.</li>
+
+<li>The "t" and "f" inline assembly constraints for the X87 floating point stack
+ now work. However, the "u" constraint is still not fully supported.</li>
+
+</ul>
+
+</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="targetspecific">Target Specific Improvements</a>
+<a name="targetspecific">Other Target Specific Improvements</a>
</div>
<div class="doc_text">
</p>
<ul>
-<li>Evan contributed support to the X86 backend to model the mod/ref behavior
-of the EFLAGS register explicitly in all instructions. This gives more freedom
-to the scheduler, and is a more explicit way to model the instructions.</li>
-<li>Dale contributed support for exception handling on Darwin/x86-64 and
-Darwin/PPC.</li>
-<li>Evan turned on if-conversion by default for ARM, allowing LLVM to take
-advantage of its predication features.</li>
-<li>Bruno added PIC support to the MIPS backend, fixed many bugs and improved
-support for architecture variants.</li>
-<li>Arnold Schwaighofer added support for X86 tail calls (limitations?
-details?).</li>
-<li>Evan contributed several enhancements to Darwin/x86 debug information,
-and improvements at -O0 (details?).</li>
-<li>Duncan added x86-64 support for trampolines (pointers to nested functions).</li>
+<li>The LLVM C backend now supports vector code.</li>
</ul>
</div>
+
+
<!--=========================================================================-->
<div class="doc_subsection">
<a name="otherimprovements">Other Improvements</a>
</p>
<ul>
-<li>Gordon expanded and updated the <a href="Passes.html">LLVM Analysis and
-Transformation Passes</a> reference to include descriptions for each pass.</li>
-
-<li>We rewrote the lexer and parser used by TableGen to make them simpler
-and cleaner. This gives tblgen support for 'caret diagnostics'. The .ll file
-lexer was also rewritten to support caret diagnostics but doesn't use this
-support yet.</li>
-
-<li>Dale has been grinding through the GCC testsuite, and marked many
-LLVM-incompatible tests as not-to-be-run (for example, if they are grepping
-through some GCC dump file that LLVM doesn't produce), he also found and fixed
-many LLVM bugs exposed by the testsuite.</li>
+<li>LLVM now builds with GCC 4.3.</li>
+<li>Bugpoint now supports running custom scripts (with the <tt>-run-custom</tt>
+ option) to determine how to execute the command and whether it is making
+ forward process.</li>
</ul>
</div>
<p>LLVM is known to work on the following platforms:</p>
<ul>
-<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
+<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
(and probably other unix-like systems).</li>
<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
64-bit modes.</li>
<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
support is available for native builds with Visual C++).</li>
-<li>Sun UltraSPARC workstations running Solaris 8.</li>
+<li>Sun UltraSPARC workstations running Solaris 10.</li>
<li>Alpha-based machines running Debian GNU/Linux.</li>
-<li>Itanium-based machines running Linux and HP-UX.</li>
+<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
</ul>
-<p>The core LLVM infrastructure uses
-<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
+<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
to the machine and operating system on which it is built. However, minor
porting may be required to get LLVM to work on new platforms. We welcome your
portability patches and reports of successful builds or error messages.</p>
be broken or unreliable, or are in early development. These components should
not be relied on, and bugs should not be filed against them, but they may be
useful to some people. In particular, if you would like to work on one of these
-components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
+components, please contact us on the <a
+href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
- LLVM 2.3.</li>
-<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
-<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
+<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
+<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
value for this option.</li>
-<li>The llvmc tool is not supported.</li>
</ul>
</div>
<div class="doc_text">
<ul>
-<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
- assembly that uses the X86 floating point stack</a>.</li>
-<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
- problems</a> on operating systems that don't require 16-byte stack alignment
- (including most non-darwin OS's like linux).</li>
-<li>The X86 backend generates inefficient floating point code when configured to
- generate code for systems that don't have SSE2.</li>
+ <li>The X86 backend does not yet support
+ all <a href="http://llvm.org/PR879">inline assembly that uses the X86
+ floating point stack</a>. It supports the 'f' and 't' constraints, but not
+ 'u'.</li>
+ <li>The X86 backend generates inefficient floating point code when configured
+ to generate code for systems that don't have SSE2.</li>
+ <li>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
+ to <a href="http://llvm.org/PR2255">several</a>
+ <a href="http://llvm.org/PR2257">bugs</a> in FP stackifier
</ul>
</div>
results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
</li>
-<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
+<li>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.</li>
</ul>
output with code built with other compilers, particularly for floating-point
programs.</li>
-<li>Defining vararg functions is not supported (but calling them is ok).</li>
+<li>Defining vararg functions is not supported (but calling them is OK).</li>
<li>The Itanium backend has bitrotted somewhat.</li>
</ul>
<div class="doc_text">
<ul>
-<li><a href="http://llvm.org/PR802">The C backend does not support inline
- assembly code</a>.</li>
-<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
- yet</a>.</li>
+<li><a href="http://llvm.org/PR802">The C backend has only basic support for
+ inline assembly code</a>.</li>
<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
- C++ code compiled with LLC or native compilers.</li>
+ C++ code compiled with llc or native compilers.</li>
<li>The C backend does not support all exception handling constructs.</li>
</ul>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c-fe">Known problems with the C front-end</a>
-</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ada-fe">Known problems with the Ada front-end</a>
-</div>
-
-<div class="doc_text">
-The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
-technology and problems should be expected.
-<ul>
-<li>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 <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>.
-Workaround: configure with --disable-bootstrap.</li>
-<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
-fail (c380004 also fails with gcc-4.2 mainline).</li>
-<li>Many 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
-crashing if an exception is raised. Workaround: do not use -E.</li>
-<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
-or finish at a non-byte offset</a> in a record. Workaround: do not pack records
-or use representation clauses that result in a field of a non-discrete type
-starting or finishing in the middle of a byte.</li>
-<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
-as generated by the Ada binder to be invalid</a>.
-Workaround: hand edit the file to use pointers for argv and envp rather than
-integers.</li>
-<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
-</ul>
-</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="fortran-fe">Known problems with the Fortran front-end</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
-<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
-<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
-</ul>
+ <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
</div>
<!-- _______________________________________________________________________ -->
Optimization</a> on most platforms "out-of-the-box". Please inquire on the
llvmdev mailing list if you are interested.</p>
-</div>
-
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- Notes
-</div>
-
-<div class="doc_text">
-<ul>
-
-<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
- See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
-</li>
-
-<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
- <ol>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
+<p>The only major language feature of GCC not supported by llvm-gcc is
+ the <tt>__builtin_apply</tt> family of builtins. However, some extensions
+ are only supported on some targets. For example, trampolines are only
+ supported on some targets (these are used when you take the address of a
+ nested function).</p>
- As in Algol and Pascal, lexical scoping of functions.
- Nested functions are supported, but llvm-gcc does not support
- taking the address of a nested function (except on X86 targets)
- or non-local gotos.</li>
-
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
-
- Declaring that functions have no side effects or that they can never
- return.<br>
-
- <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
- <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
- <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
- <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
- <tt>noreturn</tt>, <tt>nothrow</tt>, <tt>pure</tt>, <tt>regparm</tt>
- <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
- <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
-
- <b>Ignored:</b> <tt>malloc</tt>,
- <tt>no_instrument_function</tt></li>
- </ol>
-</li>
-
-<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
-
- <ol>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
- Other built-in functions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
- Specifying attributes of variables.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
- Arrays whose length is computed at run time.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
-or arrays as values.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character <ESC>.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
- </ol></li>
-
-</ul>
-
-<p>If you run into GCC extensions which have not been included in any of these
-lists, please let us know (also including whether or not they work).</p>
+<p>If you run into GCC extensions which are not supported, please let us know.
+</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c++-fe">Known problems with the C++ front-end</a>
+ <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
</div>
<div class="doc_text">
itself, Qt, Mozilla, etc.</p>
<ul>
-<li>Exception handling only works well on the X86 and PowerPC targets.
-It works well for x86-64 darwin but not x86-64 linux.</li>
+<li>Exception handling works well on the X86 and PowerPC targets, including
+X86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
+supported on X86-64 linux, but that is disabled by default in this release.</li>
</ul>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
+</div>
+
+<div class="doc_text">
+The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
+technology and problems should be expected.
+<ul>
+<li>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 <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>.
+Workaround: configure with --disable-bootstrap.</li>
+<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
+fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
+<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
+<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
+reports most tests as having failed even though they pass.</li>
+<li>The -E binder option (exception backtraces)
+<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
+crashing if an exception is raised. Workaround: do not use -E.</li>
+<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
+or finish at a non-byte offset</a> in a record. Workaround: do not pack records
+or use representation clauses that result in a field of a non-discrete type
+starting or finishing in the middle of a byte.</li>
+<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
+'main' as generated by the Ada binder to be invalid</a>.
+Workaround: hand edit the file to use pointers for <tt>argv</tt> and
+<tt>envp</tt> rather than integers.</li>
+<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
+ignored</a>.</li>
+</ul>
+</div>
<!-- *********************************************************************** -->
<div class="doc_section">
projects / oota-llvm.git / blobdiff