-
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<head>
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- <title>LLVM 2.3 Release Notes</title>
+ <title>LLVM 2.5 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.3 Release Notes</div>
-
+<div class="doc_title">LLVM 2.5 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="#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>
-<!-- Done through Week-of-Mon-20080324.txt -->
-
<!-- *********************************************************************** -->
<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 2.3. 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>
+<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="changes">Major Changes and Sub-project Status</a>
+ <a name="subproj">Sub-project Status Update</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
-
-<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>
+<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 2.3:
- Machine LICM
- Machine Sinking
- LegalizeDAGTypes
- -->
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="changes">Major Changes in LLVM 2.3</a>
+<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
</div>
<div class="doc_text">
-<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>
+<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>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>
+<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="otherprojects">Other LLVM Sub-Projects</a>
+<a name="clangsa">Clang Static Analyzer</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 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 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>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>
-<tt>svn co http://llvm.org/svn/llvm-project/vmkit/trunk vmkit</tt>
-</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_subsubsection">
-<a name="clang">Clang</a>
+<div class="doc_subsection">
+<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>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>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>
-<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>
+<li>?</li>
+</ul>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
- <a name="whatsnew">What's New?</a>
+ <a name="whatsnew">What's New in LLVM?</a>
</div>
<!-- *********************************************************************** -->
+<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="majorfeatures">Major New Features</a>
<div class="doc_text">
-<p>LLVM 2.3 includes several major new capabilities:</p>
+<p>LLVM 2.5 includes several major new capabilities:</p>
<ul>
-<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><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
+-->
</ul>
<div class="doc_text">
-<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>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>
-<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>
+<ul>
+<li>?</li>
+</ul>
</div>
</div>
<div class="doc_text">
-<p>New features include:
-</p>
-
-
-Common linkage?
-
-Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize",
-"__sync_val_compare_and_swap", etc
+<p>New features include:</p>
<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>
+<li>?</li>
+
</ul>
-
+
</div>
<!--=========================================================================-->
<div class="doc_text">
-<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>
+<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>
<ul>
-<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>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>?</li>
-<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
-<tt>memset</tt> is now more aggressive.</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>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>
</div>
<div class="doc_text">
-<p>We put a significant amount of work into the code generator infrastructure,
+<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>The code generator now has support for carrying information about memory
- references throughout the entire code generation process, via the
- <a href="http://llvm.org/doxygen/classllvm_1_1MachineMemOperand.html">
- MachineMemOperand</a> class. In the future this will be used to improve
- both pre-pass and post-pass scheduling, and to improve compiler-debugging
- output.</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, particularly in the instruction selection phase, register
- allocation, scheduling, and tail merging/jump threading.</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>
-<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="x86specific">X86/X86-64 Specific Improvements</a>
+<a name="targetspecific">Target Specific Improvements</a>
</div>
<div class="doc_text">
</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>Support for Win64 was added. This includes code generation itself, JIT
- support and necessary changes to llvm-gcc.</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>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>The X86 backend supports stack realignment, which is particularly useful for
- vector code on OS's without 16-byte aligned stacks.</li>
-
-<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>
-
-<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>
-
+<li>?</li>
</ul>
-
+
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="targetspecific">Other Target Specific Improvements</a>
+<a name="otherimprovements">Other Improvements</a>
</div>
<div class="doc_text">
-<p>New target-specific features include:
+<p>New features include:
</p>
<ul>
-<li>The LLVM C backend now supports vector code.</li>
-</ul>
-
-</div>
+<li>?</li>
+</ul>
+</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="otherimprovements">Other Improvements</a>
+<a name="changes">Major Changes and Removed Features</a>
</div>
<div class="doc_text">
-<p>New features include:
-</p>
+
+<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>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>
+
+<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 (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 (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>
<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>
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
+<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>
</ul>
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
+ <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>
</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>
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>
<a name="c-fe">Known problems with the llvm-gcc C front-end</a>
</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>
+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
itself, Qt, Mozilla, etc.</p>
<ul>
-<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>
+<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_subsection">
+ <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
+</div>
+
+<div class="doc_text">
+<ul>
+<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>
+</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
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 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 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>
<hr>
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