+
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<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>
<!-- *********************************************************************** -->
<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>LLVM 2.2 was the last LLVM release to support llvm-gcc 4.0 and llvm-upgrade.
-llvm-gcc 4.0 has been replaced with llvm-gcc 4.2. llvm-upgrade 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 regressionn
-test suite no longer depends on llvm-upgrade, which makes it run faster.</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 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
- IRBuilder.</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
+ <a href="http://llvm.org/doxygen/classllvm_1_1IRBuilder.html">IRBuilder</a>.
+ </li>
+<li>MRegisterInfo was renamed to
+ <a href="http://llvm.org/doxygen/classllvm_1_1TargetRegisterInfo.html">
+ TargetRegisterInfo</a>.</li>
+<li>The MappedFile class is gone, please use
+ <a href="http://llvm.org/doxygen/classllvm_1_1MemoryBuffer.html">
+ MemoryBuffer</a> 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>
+<li>The ConstantFP::get method that uses APFloat now takes one argument
+ instead of two. The type argument has been removed, and the type is
+ now inferred from the size of the given APFloat value.</li>
+
+</ul>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="majorfeatures">Major New Features</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>
-<p>LLVM 2.3 includes several major new capabilities:</p>
+<!--=========================================================================-->
+<div class="doc_subsubsection">
+<a name="vmkit">vmkit</a>
+</div>
-<ul>
-<li>Multiple Return Value Support</li>
+<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>
+<div class="doc_code">
+<pre>svn co http://llvm.org/svn/llvm-project/vmkit/trunk vmkit</pre>
+</div>
-<li><p>LLVM 2.3 includes a complete reimplementation of the "llvmc" tool. It is
-designed to overcome several problems of the original llvmc and to provide a
-superset of the features as the 'gcc' driver.</p>
+</div>
-<p>The main features of llvmc2 is:</p>
+<!--=========================================================================-->
+<div class="doc_subsubsection">
+<a name="clang">Clang</a>
+</div>
-<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 edged in the abstract graph.</li>
-</l>The 'language' for driver behaviour 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>
+<div class="doc_text">
-</li>
+<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>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 focuses on automatically finding
+bugs in C and Objective-C code.</p>
+
+</div>
+
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="whatsnew">What's New?</a>
+</div>
+<!-- *********************************************************************** -->
-<li>Reimplemented <a href="LinkTimeOptimization.html">LTO interface</a> in
- C.</li>
+<div class="doc_text">
+<p>LLVM 2.3 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>
-<li>kaleidoscope tutorial in ocaml.</li>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="majorfeatures">Major New Features</a>
+</div>
+
+<div class="doc_text">
+
+<p>LLVM 2.3 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>
+</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>
</ul>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="frontends">llvm-gcc 4.2 Improvements and Clang</a>
+<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
</div>
<div class="doc_text">
-<p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end.</p>
+<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end, and includes support
+for the C, C++, Objective-C, Ada, and Fortran front-ends.</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>
+<ul>
+<li>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.</li>
+
+<li>Fortran <tt>EQUIVALENCE</tt>s are now supported by the gfortran
+front-end.</li>
-<p>llvm-gcc 4.2 includes many other fixes which improve conformance with the
-relevant parts of the GCC testsuite.</p>
+<li>llvm-gcc 4.2 includes many other fixes which improve conformance with the
+relevant parts of the GCC testsuite.</li>
-<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 2.3 release. If you are interested in
-this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
+</ul>
</div>
<p>New features include:
</p>
+<ul>
+<li>LLVM IR now directly represents "common" linkage, instead of representing it
+as a form of weak linkage.</li>
-Common linkage?
-
-Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize"
+<li>LLVM IR now has support for atomic operations, and this functionality can be
+accessed through the llvm-gcc "<tt>__sync_synchronize</tt>",
+"<tt>__sync_val_compare_and_swap</tt>", and related builtins. Support for
+atomics are available in the Alpha, X86, X86-64, and PowerPC backends.</li>
-<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>The C and Ocaml bindings have extended to 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>MemOperand in the code generator: describe me!.</li>
-<li>Target-independent codegen infastructure now uses LLVM's APInt class for
- handling integer values, which allow 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>Several compile time speedups for code with large basic blocks.</li>
-<li>Several improvements which make llc's <tt>--view-sunit-dags</tt>
- visualization of scheduling dependency graphs easier to understand.</li>
+
+<li><p>Loop index set splitting on by default.
+This transformation hoists conditions from loop bodies and reduces a loop's
+iteration space to improve performance. For example,</p>
+
+<div class="doc_code">
+<pre>
+for (i = LB; i < UB; ++i)
+ if (i <= NV)
+ LOOP_BODY
+</pre>
+</div>
+
+<p>is transformed into:</p>
+
+<p><div class="doc_code">
+<pre>
+NUB = min(NV+1, UB)
+for (i = LB; i < NUB; ++i)
+ LOOP_BODY
+</pre>
+</div>
+</p>
+</li>
+
+<li>LLVM now 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>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. The new ADCE pass is
+no longer based on control dependence, making it run faster.</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>
+
+<li>Several optimizations have been sped up, leading to faster code generation
+ with the same code quality.</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 2.3 optimizers support a few major enhancements:</p>
+<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>
<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
+ <a href="http://llvm.org/doxygen/classllvm_1_1APInt.html">APInt</a>
+ class to handle integer values, which allows it to support integer types
+ larger than 64 bits (for example i128). 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>Loop index set splitting on by default: describe me.</li>
-<li>LLVM includes a new memcpy optimization pass which optimizes out dead
-memcpy calls, unneeded copies of aggregates, and handles the return slot
-optimization. The LLVM optimizer now notices long sequences of consequtive
-stores and merges them into memcpy's where profitable.</li>
-<li>Alignment detection for vector memory references and for memcpy and
-memset is now more aggressive.</li>
+<li>LLVM 2.3 includes 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 <a
+ href="CodeGenerator.html#tailcallopt">tail calls</a> on X86/32 and initial
+ support for tail calls on PowerPC 32 (it may also work on PowerPC 64 but is
+ not thoroughly tested).</li>
</ul>
</div>
<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
+ 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.</li>
-
+ 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>
-
+ point stack. This is important because most X86 ABIs require return values
+ to be on the X87 Floating Point stack, but most CPUs prefer computation in
+ the SSE units.</li>
+
<li>The X86 backend supports stack realignment, which is particularly useful for
- vector code on OS's without 16-byte aligned stacks.</li>
+ vector code on OS's without 16-byte aligned stacks, such as Linux and
+ Windows.</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>
-
+ 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>128-bit integers are now supported on X86-64 targets. This can be used
+ through <tt>__attribute__((TImode))</tt> in llvm-gcc.</li>
+
+<li>The register allocator can now rematerialize PIC-base computations, which is
+ an important optimization for register use.</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>
</p>
<ul>
-<li>The LLVM C backend now supports vectors code.</li>
-
-
+<li>The LLVM C backend now supports vector code.</li>
+<li>The Cell SPU backend includes a number of improvements. It generates better
+ code and its stability/completeness is improving.</li>
</ul>
</div>
<ul>
<li>LLVM now builds with GCC 4.3.</li>
-<li>llvm2cpp tool was moved into llc, use llc -march=cpp</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 GNU autoconf to adapt itself
<ul>
<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
+<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
value for this option.</li>
</ul>
<div class="doc_text">
<ul>
-<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>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 position-independent code (PIC)
+ generation on Linux targets.</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 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>
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>
<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
<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, which are used when you take the address of a
- nested function.</p>
+ 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>
<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>
+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>
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
+<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>
+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>
+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>
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 llvm-gcc 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>
+<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">
<a name="additionalinfo">Additional Information</a>
projects / oota-llvm.git / blobdiff