<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 1.4 Release Notes</title>
+ <title>LLVM 1.7 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 1.4 Release Notes</div>
+<div class="doc_title">LLVM 1.7 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</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>
- <ul>
- <li><a href="#experimental">Experimental features included in this
- release</a>
- <li><a href="#core">Known problems with the LLVM Core</a>
- <li><a href="#c-fe">Known problems with the C Front-end</a>
- <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
- <li><a href="#x86-be">Known problems with the X86 Back-end</a>
- <li><a href="#sparcv9-be">Known problems with the SparcV9 Back-end</a>
- <li><a href="#ppc-be">Known problems with the PowerPC Back-end</a>
- <li><a href="#c-be">Known problems with the C back-end</a>
- </ul></li>
<li><a href="#additionalinfo">Additional Information</a></li>
</ol>
<div class="doc_author">
- <p>Written by the <a href="http://llvm.
cs.uiuc.edu">LLVM team</a><p>
+ <p>Written by the <a href="http://llvm.
org">LLVM Team</a><p>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This document contains the release notes for the LLVM compiler
-infrastructure, release 1.4. Here we describe the status of LLVM, including any
-known problems and improvements from the previous release. The most up-to-date
-version of this document can be found on the <a
-href="http://llvm.cs.uiuc.edu/releases/1.4/">LLVM 1.4 web site</a>. If you are
+infrastructure, release 1.7. Here we describe the status of LLVM, including any
+known problems and major improvements from the previous release. The most
+
up-to-date version of this document can be found on the <a
+href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
not reading this on the LLVM web pages, you should probably go there because
this document may be updated after the release.</p>
<p>For more information about LLVM, including information about the latest
-release, please check out the <a href="http://llvm.cs.uiuc.edu">main LLVM
+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>
-<p>Note that if you are reading this file from CVS, this document applies
-to the <i>next</i> release, not the current one. To see the release notes for
-the current or previous releases, see the <a
-href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
+<p>Note that if you are reading this file from CVS 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 the current or previous releases, see the <a
+href="http://llvm.org/releases/">releases page</a>.</p>
</div>
<div class="doc_text">
-<p>This is the fifth public release of the LLVM compiler infrastructure.</p>
-
-<p> At this time, LLVM is known to correctly compile on a broad range of
-C and C++ programs, including the SPEC CPU95 & 2000 suite. This release
-includes several major enhancements to the LLVM system, including a new
-PowerPC JIT, enhancements to the C/C++ front-end to provide source line number
-information in LLVM, a new <a href="CommandGuide/html/llvmc.html">compiler
-driver</a>, and several other enhancements listed below. It also includes
-bug fixes for those problems found since the 1.3 release.</p>
-
-<p>Note that this release seperates the LLVM Program Testsuite out of the
-main LLVM distribution into a seperate CVS repository and tarball. This
-reduces the size of the main LLVM distribution. Also note that LLVM now
-builds tools into llvm/Debug/bin by default instead of llvm/tools/Debug.</p>
+<p>This is the eighth public release of the LLVM Compiler Infrastructure. This
+release incorporates a large number of enhancements and new features,
+including vector support (Intel SSE and Altivec), a new GCC4.0-based
+C/C++ front-end, Objective C/C++ support, inline assembly support, and many
+other big features.
+</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="newfeatures">This release implements the following new features:</a>
+<div class="doc_subsection">
+<a name="newfeatures">New Features in LLVM 1.7</a>
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="llvmgcc4">GCC4.0-based llvm-gcc
+front-end</a></div>
+
<div class="doc_text">
-<ol>
- <li>LLVM now includes a Just-In-Time compiler for the PowerPC target.</li>
- <li>llvmgcc and llvmg++ now emit source line number information when '-g' is
- passed in, making it possible to map from LLVM code back to source.
- This information is currently used by llvm-db and can be used with other
- tools and passes.</li>
- <li>The test/Programs hierarchy <a href="http://llvm.cs.uiuc.edu/PR257">has
- been moved out of the main LLVM tree</a> into a separate CVS repository and
- tarball. This shrinks the distribution size of LLVM itself significantly.
- </li>
- <li>LLVM now optimizes global variables more aggressively than it did
- before.</li>
- <li>LLVM now includes the new '<tt>undef</tt>' value and
- <a href="LangRef.html#i_unreachable"><tt>unreachable</tt></a> instruction,
- which give the optimizer more information about the behavior of the
- program.
- </li>
- <li>Bytecode compression with bzip2 has been implemented. All bytecode files
- generated by LLVM will now be compressed by default. Compression can be
- disabled with the <tt>-disable-compression</tt> option to the tools that can
- generate bytecode files.
- </li>
- <li>A generic <a href="CommandGuide/html/llvmc.html">compiler driver</a>
- (llvmc) and
- an associated <a href="CommandGuide/html/llvm-ld.html">generic linker</a>
- (llvm-ld) have been added. The compiler driver is generic because it can be
- configured
- to pre-process, translate, optimize, assemble, and link code from any source
- language with an LLVM front-end. This makes it easier for compiler writers
- to hide the multiple steps required to compile a program (compiling,
- optimizing, linking runtime libraries, etc) in one simple command.
- </li>
- <li>The <a href="http://llvm.cs.uiuc.edu/PR263">dependent libraries</a>
- feature has been implemented. This allows front end compilers to indicate in
- the bytecode which libraries the bytecode needs to be linked with. Both the
- C/C++ and Stacker front ends support generating the required dependencies.
- The linker now supports using this information to ensure required libaries are
- linked into the module. This minimizes the need to use the <tt>-l</tt> option
- when using <a href="CommandGuide/html/llvmc.html"><tt>llvmc</tt></a>
- </li>
- <li>The LLVM makefiles have been improved to build LLVM much faster and
- includes new targets (like dist-check, uninstall). One important user-visible
- change is that libraries and tools will now be built into
- <tt>$builddir/Debug/{bin,lib}</tt>
- instead of <tt>$builddir/tools/Debug</tt> and <tt>$builddir/lib/Debug</tt>
- (Similarly for <tt>Release</tt> and <tt>Profile</tt> builds).
- </li>
- <li>The LLVM source code is much more compatible with Microsoft Visual C++,
- including the JIT and runtime-code generation, though the entire system
- may not work with it.
- </li>
- <li>The JIT-Target interfaces <a href="http://llvm.cs.uiuc.edu/PR283">are
- now much simpler</a> and more powerful.
- </li>
- <li>LLVM now provides llvm-ar and llvm-ranlib tools for working with archives
- of LLVM bytecode files.</li>
- <li>zlib and libpng are <a href="http://llvm.cs.uiuc.edu/PR417">no longer
- included in the main LLVM tarball</a>.</li>
- <li>The LLVM code generator now automatically generates assembly code writers
- from an abstract target descriptions, eliminating the need to write
- assembly printers manually.</li>
- <li>LLVM regression and feature tests now use DejaGNU instead of QMTest.</li>
-</ol>
-</div>
+<p>LLVM 1.7 includes a brand new llvm-gcc, based on GCC 4.0.1. This version
+of llvm-gcc solves many serious long-standing problems with llvm-gcc, including
+all of those blocked by the <a href="http://llvm.org/PR498">llvm-gcc 4 meta
+bug</a>. In addition, llvm-gcc4 implements support for many new features,
+including GCC inline assembly, generic vector support, SSE and Altivec
+intrinsics, and several new GCC attributes. Finally, llvm-gcc4 is
+significantly faster than llvm-gcc3, respects -O options, its -c/-S options
+correspond to GCC's (they emit native code), supports Objective C/C++, and
+it has debugging support well underway.</p>
+<p>If you can use it, llvm-gcc4 offers significant new functionality, and we
+hope that it will replace llvm-gcc3 completely in a future release.
+Unfortunately, it does not currently support C++ exception handling at all, and
+it only works on Apple Mac OS/X machines with X86 or PowerPC processors.
+</p>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-In this release, the following missing features were implemented:
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="inlineasm">Inline Assembly
+Support</a></div>
+
<div class="doc_text">
-<ol>
- <li><a href="http://llvm.cs.uiuc.edu/PR419">JIT interface should support
- arbitrary calls</a>
- </li>
- <li>The <tt>llvm-ar</tt> tool was previously incomplete and didn't properly
- support other ar(1) implementations. This has been corrected. <tt>llvm-ar</tt>
- now fully supports all archive editing functions, table of contents listing,
- extraction, and printing. It can also read BSD4.4/MacOSX and SVR4 style
- archives. See <a href="CommandGuide/html/llvm-ar.html">llvm-ar</a> for
- details.
- </li>
-</ol>
+<p>The LLVM IR and llvm-gcc4 front-end now fully support arbitrary GCC <a
+href="LangRef.html#inlineasm">inline assembly</a>. The LLVM X86 and PowerPC
+code generators have initial support for it,
+being able to compile basic statements, but are missing some features. Please
+report any inline asm statements that crash the compiler or that are miscompiled
+as bugs.</p>
</div>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="qualityofimp">In this release, the following Quality of Implementation
-issues were fixed:</a>
-</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="newsparc">New SPARC backend</a></div>
<div class="doc_text">
-<ol>
- <li>The linker no longer <a href="http://llvm.cs.uiuc.edu/PR426">emits many
- useless warnings</a> when linking C++ programs.
- </li>
- <li>The LLVM <a href="http://llvm.cs.uiuc.edu/PR352">#include namespace</a>
- has been made consistent. Files in <tt>llvm/include/{Support,Config}</tt>
- are now located in <tt>llvm/include/llvm/{Support,Config}</tt>.
- </li>
- <li>The names of the libraries generated by compiling LLVM source have been
- changed to ensure they do not conflict with other packages upon installation.
- Each LLVM library is now prefixed with LLVM and uses mixed clase. For example,
- the library <tt>libasmparser.a</tt> in 1.3 has become
- <tt>libLLVMAsmParser.a</tt> in release 1.4.
- </li>
- <li>The C++ frontend no longer expands and emits <a
- href="http://llvm.cs.uiuc.edu/PR459">all inline functions, even if they
- are unused</a>. It now properly tracks which functions are needed and
- only compiles those.</li>
-
- <li>Many improvements in the <a href="http://llvm.cs.uiuc.edu/PR256">autoconf
- and makefile systems</a> have been implemented.</li>
-</ol>
-</div>
+<p>LLVM 1.7 includes a new, fully functional, SPARC backend built in the
+target-independent code generator. This SPARC backend includes support for
+SPARC V8 and SPARC V9 subtargets (controlling whether V9 features can be used),
+and targets the 32-bit SPARC ABI.</p>
+
+<p>The LLVM 1.7 release is the last release that will include the LLVM "SparcV9"
+backend, which was the very first LLVM native code generator. It will
+be removed in LLVM 1.8, being replaced with the new SPARC backend.</p>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="codequality">This release includes the following Code Quality
-improvements:</a>
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="genvector">Generic Vector Support
+</a></div>
+
<div class="doc_text">
-<ol>
- <li>The optimizer produces <a href="http://llvm.cs.uiuc.edu/PR362">more
- efficient code for std::min/std::max</a> and other similar functions.</li>
- <li>The X86 backend generates substantially faster code for floating point
- intensive programs.</li>
- <li>The PowerPC backend generates more efficient code in many common
- scenarios.</li>
-</ol>
+
+<p>LLVM now includes significantly extended support for SIMD vectors in its
+core instruction set. It now includes three new instructions for manipulating
+vectors: <a href="LangRef.html#i_extractelement"><tt>extractelement</tt></a>,
+<a href="LangRef.html#i_insertelement"><tt>insertelement</tt></a>, and
+<a href="LangRef.html#i_shufflevector"><tt>shufflevector</tt></a>. Further,
+many bugs in vector handling have been fixed, and vectors are now supported by
+the target-independent code generator. For example, if a vector operation is
+not supported by a particular target, it will be correctly broken down and
+executed as scalar operations.</p>
+
+<p>Because llvm-gcc3 does not support GCC generic vectors or vector intrinsics,
+llvm-gcc4 must be used.</p>
</div>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="bugfix">In this release, the following bugs in the previous release
-were fixed:</a>
+
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="ssealtivec">Intel SSE and PowerPC
+Altivec support
+</a></div>
+
+<div class="doc_text">
+
+<p>The LLVM X86 backend now supports Intel SSE 1, 2, and 3, and now uses scalar
+SSE operations to implement scalar floating point math when the target supports
+SSE1 (for floats) or SSE2 (for doubles). Vector SSE instructions are generated
+by llvm-gcc4 when the generic vector mechanism or specific SSE intrinsics are
+used.
+</p>
+
+<p>The LLVM PowerPC backend now supports the Altivec instruction set, including
+both GCC -maltivec and -faltivec modes. Altivec instructions are generated
+by llvm-gcc4 when the generic vector mechanism or specific Altivec intrinsics
+are used.
+</p>
+
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="optimizernew">Optimizer
+Improvements</a></div>
+
<div class="doc_text">
+<ul>
+<li>The Loop Unswitching pass (<tt>-loop-unswitch</tt>) has had several bugs
+ fixed, has several new features, and is enabled by default in llvmgcc3
+ now.</li>
+<li>The Loop Strength Reduction pass (<tt>-loop-reduce</tt>) is now enabled for
+ the X86 and Alpha backends.</li>
+<li>The Instruction Combining pass (<tt>-instcombine</tt>) now includes a
+ framework and implementation for simplifying code based on whether computed
+ bits are demanded or not.</li>
+<li>The Scalar Replacement of Aggregates pass (<tt>-scalarrepl</tt>) can now
+ promote simple unions to registers.</li>
+<li>The Reassociation pass (<tt>-reassociate</tt>) can now
+ factor expressions, e.g. turning "A*A+A*B" into "A*(A+B)".</li>
+<li>Several LLVM passes are <a href="http://llvm.org/PR681">significantly
+faster</a>.</li>
+</ul>
+</div>
-<p>Bugs fixed in the LLVM Core:</p>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="codgennew">Code Generator
+Improvements</a></div>
-<ol>
- <li><a href="http://llvm.cs.uiuc.edu/PR420">[licm] LICM invalidates alias
- analysis info and uses broken information</a> (optimizer crash)</li>
- <li><a href="http://llvm.cs.uiuc.edu/PR422">[asmwriter] Asmwriter is really
- slow for functions with lots of values</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR423">[anders-aa] Andersen's AA is
- completely broken in LLVM 1.3</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR430">[bcwriter] Empty compaction
- tables defined</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR227">[X86] llc output for functions
- w/certain names tickles GNU 'as' bugs</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR472">[cbackend] Static globals are
- prototyped as 'extern'</a></li>
-</ol>
+<div class="doc_text">
+<ul>
+<li>LLVM has a new prepass (before register allocation) list scheduler, which
+ supports bottom-up and top-down scheduling, pluggable priority functions and
+ pluggable hazard recognizers. The X86 backend uses this to reduce register
+ pressure and RISC targets schedule based on operation latency.</li>
+<li>The tblgen-based target description framework introduced in LLVM 1.6 has
+ several new features, useful for targets that can fold loads and stores into
+ operations, and features that make the .td files more expressive.</li>
+<li>The instruction selector is significantly faster in 1.7 than in 1.6.</li>
+<li>The X86, Alpha and Itanium backends use new DAG-DAG instruction selectors,
+ making them easier to maintain and generate slightly better code.</li>
+<li>The X86 backend now supports generation of Scalar SSE code for scalar FP
+ expressions. LLVM provides significantly better performance with Scalar SSE
+ instructions than it does with the Intel floating point stack
+ instructions.</li>
+<li>The Itanium backend now has a bundling pass, which improves performance
+ by ~10% and reduces code size (previously it unconditionally inserted a stop
+ bit after every instruction).</li>
+</ul>
+</div>
-<p>Bugs in the C/C++ front-end:</p>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="othernew">Other New Features</a></div>
-<ol>
- <li><a href="http://llvm.cs.uiuc.edu/PR445">[llvmg++] not enough templates are
- instantiated</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR450">[llvmg++] Extern const globals
- cannot be marked 'constant' if they have nontrivial ctors or dtors</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR461">[llvmgcc] Crash compiling unnamed
- bitfield which does not increase struct size</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR424">[llvmgcc] llvmgcc emits invalid
- constant exprs</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR421">[llvmg++] Crash initializing
- array with constructors in hard EH situations</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR397">[llvm-gcc] Inline function
- redefinitions error due to 'asm' function rename</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an
- implicitly external function is re-declared as static</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR360">[llvmgcc] Structure field with
- non-constant offset crashes llvmgcc</a></li>
- <li><a href="http://llvm.cs.uiuc.edu/PR447">[llvmg++] Crash compiling
- friend with default argument</a></li>
-</ol>
+<div class="doc_text">
+<ul>
+<li>The Mac OS/X PowerPC and X86 backends now have initial support for
+ Darwin DWARF
+ debugging information, however, debug info generation has been disabled for
+ the 1.7 release in llvmgcc4.</li>
+<li>LLVM includes the new <a href="docs/CommandGuide/html/llvm-config.html">
+ llvm-config</a> utility, which makes it easier to build and link programs
+ against the LLVM libraries when not using the LLVM makefiles.</li>
+<li>LLVM now supports first class global ctor/dtor initialization lists, no
+ longer forcing targets to use "__main".</li>
+<li>LLVM supports assigning globals and functions to a particular section
+ in the result executable using the GCC section attribute.</li>
+<li><a href="ExtendingLLVM.html">Adding intrinsics to LLVM</a> is now
+ significantly easier.</li>
+<li>llvmgcc4 now fully supports C99 Variable Length Arrays, including dynamic
+ stack deallocation.</li>
-<p>Bugs fixed in the Sparc V9 back-end:</p>
+</ul>
+</div>
-<ol>
- <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
- failure with certain indirect calls</a></li>
-</ol>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="changes">Significant Changes in LLVM 1.7</a>
</div>
+<div class="doc_text">
+<ul>
+<li>The official LLVM URL is now <a href="http://llvm.org/">
+ http://llvm.org/</a>.</li>
+<li>The LLVM intrinsics used to be overloaded based on type: for example,
+ <a href="LangRef.html#int_ctpop"><tt>llvm.ctpop</tt></a> could work with any
+ integer datatype. They are now separated into different intrinsics with
+ suffixes to denote their argument type (e.g. <tt>llvm.ctpop.i32</tt>)). Old
+ LLVM .ll and .bc files that use these intrinsics will continue to work with
+ new LLVM versions (they are transparently upgraded by the parsers), but will
+ cause a warning to be emitted.</li>
+<li>The <tt>llvm.readport</tt>, <tt>llvm.writeport</tt>, <tt>llvm.readio</tt>,
+ and <tt>llvm.writeio</tt> intrinsics have been removed. The first two
+ were ever only supported by the X86 backend, the last two were never
+ correctly supported by any target, and none were accessible through the
+ C front-end. Inline assembly support can now be used to
+ implement these operations.</li>
+<li>The <tt>llvm-db</tt> tool had basic support for stepping through code, which
+ used the JIT. This code has been removed, and DWARF emission support added
+ instead. <tt>llvm-db</tt> still exists in CVS if someone wanted to write a
+ <tt>ptrace</tt> backend for it.</li>
+</ul>
+</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="portability">Portability and Supported Platforms</a>
<div class="doc_text">
-<p>LLVM is known to work in the following platforms:</p>
+<p>LLVM is known to work on the following platforms:</p>
<ul>
-<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
- other unix-like systems).</li>
+ <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
+ (and probably other unix-like systems).</li>
<li>Sun UltraSPARC workstations running Solaris 8.</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>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
+<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above.</li>
+<li>Alpha-based machines running Debian GNU/Linux.</li>
+<li>Itanium-based machines running Linux and HP-UX.</li>
</ul>
<p>The core LLVM infrastructure uses
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>
-<!--
-<p>Note that the LLVM build system does not currently support directories with
-spaces on them when running on Win32/cygwin. We strongly recommend running
-LLVM and the C frontend out of a top-level directory without spaces (e.g.,
-<tt>/cygdrive/c/llvm</tt>). Also, make sure to install <b>all</b> of the
-cygwin packages. By default, many important tools are not installed that
-are needed by the LLVM build process or test suite (e.g., /bin/time). Finally,
-please make sure that there are no directories with spaces in them in your
-PATH environment variable.</p>
--->
-
</div>
<!-- *********************************************************************** -->
<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
-href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
+href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
there isn't already one.</p>
</div>
components, please contact us on the llvmdev list.</p>
<ul>
-<li>The following passes are incomplete or buggy, and may be removed in future
- releases: <tt>-pgmdep, -memdep, -ipmodref, -cee, -branch-combine,
- -instloops, -paths, -pre</tt></li>
-<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
- be used to step through programs and inspect the stack.</li>
-<li>The "iterative scan" register allocator (enabled with -regalloc=iterativescan)
- is not stable.</li>
+<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
+ future release.</li>
+<li>The IA64 code generator is experimental.</li>
+<li>The Alpha JIT is experimental.</li>
+<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
+ <tt>-filetype</tt> llc option.</li>
</ul>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="build">Known problems with the Build System</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>none yet</li>
+</ul>
+</div>
+
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="core">Known problems with the LLVM Core</a>
<div class="doc_text">
<ul>
- <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.
- </li>
- <li>The JIT does not use mutexes to protect its internal data structures. As
- such, execution of a threaded program could cause these data structures to be
- corrupted.
- </li>
- <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
- mark values live across a setjmp as volatile</a>. This missing feature
- only affects targets whose setjmp/longjmp libraries do not save and restore
- the entire register file.</li>
+ <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
+ work.</li>
</ul>
</div>
<div class="doc_subsubsection">Bugs</div>
<div class="doc_text">
+
+<p>
+llvm-gcc3 has many significant problems that are fixed by llvm-gcc4. See
+ those blocked on the <a href="http://llvm.org/PR498">llvm-gcc4 meta bug</a>.
+Two major ones include:</p>
+
<ul>
-<li>C99 Variable sized arrays do not release stack memory when they go out of
+<li>With llvm-gcc3,
+ C99 variable sized arrays do not release stack memory when they go out of
scope. Thus, the following program may run out of stack space:
<pre>
for (i = 0; i != 1000000; ++i) {
}
</pre></li>
-<li>Initialization of global union variables can only be done <a
-href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
+<li>
With llvm-gcc3, Initialization of global union variables can only be done <a
+href="http://llvm.org/PR162">with the largest union member</a>.</li>
</ul>
</div>
<ul>
-<li>Inline assembly is not yet supported.</li>
-
<li>"long double" is transformed by the front-end into "double". There is no
support for floating point data types of any size other than 32 and 64
bits.</li>
return.<br>
<b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
- <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
+ <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
+ <tt>unused</tt>, <tt>used</tt>,
<tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
- <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
+ <b>Ignored:</b> <tt>noinline</tt>,
<tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
<tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
- <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
+ <b>Unsupported:</b> <tt>section</tt>, <tt>alias</tt>,
<tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
<tt>fastcall</tt>, all other target specific attributes</li>
Specifying attributes of variables.<br>
<b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
<tt>deprecated</tt>, <tt>transparent_union</tt>,
- <tt>unused</tt>, <tt>weak</tt><br>
+ <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
<b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
<tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
<tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
<tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
(currently ignored). We also support builtins for ISO C99 floating
- point comparison macros (e.g., <tt>__builtin_islessequal</tt>).</li>
+ point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
+ <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
+ <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
</ol>
<p>The following extensions <b>are</b> known to be supported:</p>
<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---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</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>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
front-end</a>.</li>
-<li><b>IA-64 specific</b>: The C++ front-end does not use <a
-href="http://llvm.cs.uiuc.edu/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>
-
</ul>
</div>
<ul>
-<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
-parser is significantly more standards compliant (and picky) than prior GCC
-versions. For more information, see the C++ section of the <a
-href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
-
<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
function and in the <tt>setjmp</tt> receiver function may not be run.
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="x86-be">Known problems with the X86 back-end</a>
+ <a name="c-be">Known problems with the C back-end</a>
</div>
<div class="doc_text">
<ul>
- <li>none yet</li>
+
+<li>The C back-end produces code that violates the ANSI C Type-Based Alias
+Analysis rules. As such, special options may be necessary to compile the code
+(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
+problem probably cannot be fixed.</li>
+
+<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
+supported</a>. This should not affect LLVM produced by the C or C++
+frontends.</li>
+
+<li>The C backend does not correctly implement the <a
+href="LangRef.html#i_stacksave"><tt>llvm.stacksave</tt></a> or
+<a href="LangRef.html#i_stackrestore"><tt>llvm.stackrestore</tt></a>
+intrinsics. This means that some code compiled by it can run out of stack
+space if they depend on these (e.g. C99 varargs).</li>
+
</ul>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
+ <a name="x86-be">Known problems with the X86 back-end</a>
</div>
<div class="doc_text">
<ul>
-<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
-several programs in the LLVM test suite</a></li>
+<li><a href="http://llvm.org/PR736">Indirect calls crash JIT on
+Darwin/x86</a>.</li>
</ul>
</div>
<div class="doc_text">
<ul>
-<li>none yet</li>
+<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
+implement ordered FP comparisons</a>.</li>
</ul>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="c-be">Known problems with the C back-end</a>
+ <a name="alpha-be">Known problems with the Alpha back-end</a>
</div>
<div class="doc_text">
<ul>
-<li>The C back-end produces code that violates the ANSI C Type-Based Alias
-Analysis rules. As such, special options may be necessary to compile the code
-(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
-problem probably cannot be fixed.</li>
+<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
+appropriate nops inserted to ensure restartability.</li>
-<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
-supported</a>. This should not affect LLVM produced by the C or C++
-frontends.</li>
+</ul>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ia64-be">Known problems with the IA64 back-end</a>
+</div>
+
+<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>
+
+</ul>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="sparc-be">Known problems with the SPARC back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
+ support the 64-bit SPARC ABI (-m64).</li>
+</ul>
+
+</div>
+
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li><a href="http://llvm.org/PR60">[sparcv9] SparcV9 backend miscompiles
+several programs in the LLVM test suite</a></li>
+<li>The SparcV9 backend is slated to be removed before the LLVM 1.8
+ release.</li>
</ul>
</div>
<div class="doc_text">
-<p>A wide variety of additional information is available on the LLVM web page,
-including mailing lists and publications describing algorithms and components
-implemented in LLVM. The web page also contains versions of the API
-documentation which is up-to-date with the CVS version of the source code. You
-can access versions of these documents specific to this release by going into
-the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
+<p>A wide variety of additional information is available on the <a
+href="http://llvm.org">LLVM web page</a>, including <a
+href="http://llvm.org/docs/">documentation</a> and <a
+href="http://llvm.org/pubs/">publications describing algorithms and
+components implemented in LLVM</a>. The web page also contains versions of the
+API documentation which is up-to-date with the CVS version of the source code.
+You can access versions of these documents specific to this release by going
+into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
<p>If you have any questions or comments about LLVM, please feel free to contact
-us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
+us via the <a href="http://llvm.org/docs/#maillist"> mailing
lists</a>.</p>
</div>
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src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
- <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
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