<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 2.5 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.2 Release Notes</div>
-
+<div class="doc_title">LLVM 2.5 Release Notes</div>
+
<ol>
<li><a href="#intro">Introduction</a></li>
- <li><a href="#whatsnew">What's New?</a></li>
+ <li><a href="#subproj">Sub-project Status Update</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>
- <li><a href="#knownproblems">Known Problems</a>
+ <li><a href="#knownproblems">Known Problems</a></li>
<li><a href="#additionalinfo">Additional Information</a></li>
</ol>
<div class="doc_author">
- <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
+ <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
</div>
-
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="intro">Introduction</a>
<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
-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>
+<p>This document contains the release notes for the LLVM Compiler
+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>
<p>For more information about LLVM, including information about the latest
release, please check out the <a href="http://llvm.org/">main LLVM
web site</a>. If you have questions or comments, the <a
-href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
-list</a> is a good place to send them.</p>
+href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
+List</a> is a good place to send them.</p>
-<p>Note that if you are reading this file from a Subversion checkout or the
+<p>Note that if you are reading this file from a Subversion checkout or the
main LLVM web page, this document applies to the <i>next</i> release, not the
-current one. To see the release notes for a specific releases, please see the
+current one. To see the release notes for a specific release, please see the
<a href="http://llvm.org/releases/">releases page</a>.</p>
</div>
+<!-- Unfinished features in 2.5:
+ Machine LICM
+ Machine Sinking
+ 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
+
+ -->
+
+ <!-- for announcement email:
+ -->
+
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="whatsnew">What's New?</a>
+ <a name="subproj">Sub-project Status Update</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>
+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 <a href="#clang">Clang Project</a> and
+the <a href="#vmkit">VMKit Project</a>.
+</p>
</div>
-<!-- Unfinished features in 2.2:
- Index Set Splitting not enabled by default
- Machine LICM
- Machine Sinking
- LegalizeDAGTypes
- -->
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="deprecation">Deprecated features in LLVM 2.2</a>
+<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</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>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. 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 <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 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_subsection">
-<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
+<a name="clangsa">Clang Static Analyzer</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 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>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>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>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>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="majorfeatures">Major New Features</a>
+<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
</div>
<div class="doc_text">
+<p>
+The <a href="http://vmkit.llvm.org/">VMKit project</a> 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>LLVM 2.2 includes several major new capabilities:</p>
+<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>Scott Michel contributed an SPU backend, which generates code for the
-vector coprocessors on the Cell processor. (Status?)</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>
-<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>
+<li>?</li>
-<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>
+</ul>
+</div>
-<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>
-<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_section">
+ <a name="whatsnew">What's New in LLVM?</a>
+</div>
+<!-- *********************************************************************** -->
-</ul>
+<div class="doc_text">
+<p>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.
+</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="coreimprovements">LLVM Core Improvements</a>
+<a name="majorfeatures">Major New Features</a>
</div>
<div class="doc_text">
-<p>New features include:
-</p>
+
+<p>LLVM 2.5 includes several major new capabilities:</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><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:
+
+xcore backend!
+fortran on darwin!
+
+.ll parser rewrite.
+GCC inliner off.
+cmake mature?
+x86 backend FS/GS segment address spaces?
+nocapture
+memdep 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
+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.
+asmprinters seperate from targets for jits
+-->
-<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>
+</ul>
-<li>Devang added LLVMFoldingBuilder, a version of LLVMBuilder that implicitly
-simplifies the code as it is constructed.</li>
+</div>
-<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>
-<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>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
+</div>
+
+<div class="doc_text">
-<li>Dan Gohman added support for vector sin, cos, and pow intrinsics.</li>
+<p>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.</p>
+<ul>
+<li>?</li>
</ul>
-
+
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="codegen">Code Generator Improvements</a>
+<a name="coreimprovements">LLVM Core 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>New features include:</p>
<ul>
+<li>?</li>
+
+</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>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>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>
+</div>
-<li>Evan added initial support for register coalescing of subregister
-references.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="optimizer">Optimizer Improvements</a>
+</div>
-<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>
+<div class="doc_text">
-<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>
+<p>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:</p>
-<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>
+<ul>
-<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>
+<li>?</li>
-<li>The MachineInstr, MachineOperand and TargetInstrDesc classes are simpler,
-more consistent, and better documented.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="optimizer">Optimizer Improvements</a>
+<a name="codegen">Code Generator 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>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>
<ul>
-
-<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>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>Evan added support for simple exit value substitution to LSR.</li>
-
-<li>Evan enhanced LSR to support induction variable reuse when the induction
-variables have different widths.</li>
+<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>
</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>?</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>?</li>
+
</ul>
-
+
+</div>
+
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="changes">Major Changes and Removed Features</a>
+</div>
+
+<div class="doc_text">
+
+<p>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
+from the previous release.</p>
+
+<ul>
+
+<li>?</li>
+</ul>
+
+
+<p>In addition, many APIs have changed in this release. Some of the major LLVM
+API changes are:</p>
+
+<ul>
+<li>?</li>
+</ul>
+
+<li>?</li>
+</ul>
+
</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="portability">Portability and Supported Platforms</a>
<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
- (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 (IA32, X86-64, AMD64, EMT-64) 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>
<div class="doc_text">
-<p>This section contains all known problems with the LLVM system, listed by
-component. As new problems are discovered, they will be added to these
-sections. If you run into a problem, please check the <a
+<p>This section contains significant known problems with the LLVM system,
+listed by component. If you run into a problem, please check the <a
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</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, MIPS, and PIC16 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> due to lack of support for the
+ 'u' inline assembly constraint and X87 floating point inline assembly.</li>
+ <li>The X86-64 backend does not yet support the LLVM IR instruction
+ <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
+ argument constructs on X86-64 by lowering them manually.</li>
</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>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="mips-be">Known problems with the MIPS back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>The O32 ABI is not fully supported.</li>
+<li>64-bit MIPS targets are not supported yet.</li>
+</ul>
+
+</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="alpha-be">Known problems with the Alpha back-end</a>
<div class="doc_text">
<ul>
-
-<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
-made where the argument is not 16-byte aligned, as required on IA64. (Strictly
-speaking this is not a bug in the IA64 back-end; it will also be encountered
-when building C++ programs using the C back-end.)</li>
-
-<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
-ABI compliant layout of v-tables</a>. In particular, it just stores function
-pointers instead of function descriptors in the vtable. This bug prevents
-mixing C++ code compiled with LLVM with C++ objects compiled by other C++
-compilers.</li>
-
-<li>There are a few ABI violations which will lead to problems when mixing LLVM
-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>The Itanium backend has bitrotted somewhat.</li>
+<li>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.</li>
</ul>
</div>
<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>
+<li>The C backend does not support arbitrary precision integers.</li>
</ul>
</div>
<!-- ======================================================================= -->
<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>
+ <a name="c-fe">Known problems with the llvm-gcc C 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>
+
+<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
+Optimization</a> on most platforms "out-of-the-box". Please inquire on the
+LLVMdev mailing list if you are interested.</p>
+
+<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>
+
+<p>If you run into GCC extensions which are not supported, please let us know.
+</p>
+
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="fortran-fe">Known problems with the Fortran front-end</a>
+ <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
</div>
<div class="doc_text">
+<p>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.</p>
+
<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>
+<li>Exception handling works well on the X86 and PowerPC targets. Currently
+ only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
</ul>
-</div>
-
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">Bugs</div>
-
-<div class="doc_text">
-
-<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
-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 class="doc_subsection">
+ <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
</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>:
-
- 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>
-
+<li>Fortran support generally works, but there are still several unresolved bugs
+ in Bugzilla. Please see the tools/gfortran component for details.</li>
+
+<li>The Fortran front-end currently does not build on Darwin (without tweaks)
+ due to unresolved dependencies on the C front-end.</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>
-
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c++-fe">Known problems with the C++ front-end</a>
+ <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
</div>
<div class="doc_text">
-
-<p>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.</p>
-
+The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
+technology and problems should be expected.
<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>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>.
+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).
+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
+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>
-
-
<!-- *********************************************************************** -->
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