<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 1.9 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 1.4 Release Notes</div>
+<div class="doc_title">LLVM 1.9 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 1.9. 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 (corresponding to LLVM CVS) 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 and 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 tenth public release of the LLVM Compiler Infrastructure. This
+release incorporates a large number of enhancements, new features, and bug
+fixes. We recommend that all users of previous LLVM versions upgrade.
+</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 1.9</a>
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="x86-64">New X86-64 Backend</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. This information can be used with llvm-db or 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++ front end and Stacker support generating the required libraries. 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 can now be run with DejaGNU.</li>
- <li>llvmgcc and llvmg++ now emit source-level line number information, making
- it possible to map from LLVM code back to source. This is currently used
- by llvm-db.</li>
-</ol>
-
+<p>LLVM 1.9 now fully supports the x86-64 instruction set on Mac OS/X, and
+supports it on Linux (and other operating systems) when compiling in -static
+mode. LLVM includes JIT support for X86-64, and supports both Intel EMT-64T
+and AMD-64 architectures. The X86-64 instruction set permits addressing a
+64-bit addressing space and provides the compiler with twice the
+number of integer registers to use.</p>
</div>
-
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-In this release, the following missing features were implemented:
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="lto">Link-Time Optimization integration
+with native linkers</a></div>
+<div class="doc_text">
+<p>LLVM now includes <a href="LinkTimeOptimization.html">liblto</a> which can
+be used to integrate LLVM Link-Time Optimization support into a native linker.
+This allows LLVM .bc to transparently participate with linking an application,
+even when some .o files are in LLVM form and some are not.</p>
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="dwarf">DWARF debugging
+support for Linux, Cygwin and MinGW on X86</a></div>
<div class="doc_text">
+<p>llvm-gcc4 now supports generating debugging info for Linux, Cygwin and MinGW.
+This extends the PPC/Darwin and X86/Darwin debugging support available in the
+1.8 release. DWARF is a standard debugging format used on many platforms.</p>
+</div>
-<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>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="optimizer">Optimizer
+Improvements</a></div>
+<div class="doc_text">
+<p>The mid-level optimizer is now faster and produces better code in many cases.
+ Significant changes include:</p>
+<ul>
+<li>LLVM includes a new 'predicate simplifier' pass, which
+ currently performs dominator tree-based optimizations.</li>
+<li>The complete loop unroll pass now supports unrolling of
+ multiple basic block loops.</li>
+<li>The 'globalopt' pass can now perform the scalar replacement of
+ aggregates transformation on some heap allocations.</li>
+<li>The globalsmodref-aa alias analysis can now track 'indirect pointer
+ globals' more accurately.</li>
+<li>The instruction combiner can now perform element propagation
+analysis of vector expressions, eliminating computation of vector elements
+that are not used.</li>
+</ul>
+
</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="codegen">Code
+Generator Enhancements</a></div>
<div class="doc_text">
+<p>
+The LLVM Target-Independent code generator now supports more target features and
+optimizes many cases more aggressively. New features include:
+</p>
-<ol>
- <li>The linker no longer <a href="http://llvm.cs.uiuc.edu/PR426">emits many
- useless warnings</a> when linking C++ programs.</a>
- </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>.</a>
- </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>
+<ul>
+<li>LLVM now includes a late branch folding pass which optimizes code
+ layout, performs several branch optzns, and deletes unreachable code.</li>
+<li>The code generator now support targets that have pre/post-increment
+ addressing modes.</li>
+<li>LLVM now supports dynamically-loadable register allocators and
+ schedulers.</li>
+<li>LLVM 1.9 includes several improvements to inline asm support,
+ including support for new constraints and modifiers.</li>
+<li>The register coalescer is now more aggressive than before,
+ allowing it to eliminate more copies.</li>
+</ul>
- <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>In addition, the LLVM target description format has itself been extended in
+ several ways:</p>
+
+<ul>
+<li>tblgen now allows definition of '<a
+ href="TableGenFundamentals.html#multiclass">multiclasses</a>' which can be
+ used to factor instruction patterns more aggressively in .td files.</li>
+<li>LLVM has a new TargetAsmInfo class which captures a variety of
+ information about the target assembly language format.</li>
+<li>.td files now support "<tt>${:foo}</tt>" syntax for encoding
+ subtarget-specific assembler syntax into instruction descriptions.</li>
+</ul>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="codequality">This release includes the following Code Quality
-improvements:</a>
-</div>
+<p>Further, several significant target-specific enhancements are included in
+LLVM 1.9:</p>
-<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>
-</div>
+<ul>
+<li>The LLVM ARM backend now supports more instructions
+ and the use of a frame pointer. It is now possible to build
+ libgcc and a simple cross compiler, but it is not considered "complete" yet.
+ </li>
+<li>LLVM supports the Win32 dllimport/dllexport linkage and
+ stdcall/fastcall calling conventions.</li>
+</ul>
-<!--=========================================================================-->
-<div class="doc_subsubsection">
-<a name="bugfix">In this release, the following bugs in the previous release
-were fixed:</a>
</div>
+<!--_________________________________________________________________________-->
+<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
<div class="doc_text">
+<p>This release includes many other improvements, including improvements to
+ the optimizers and code generators (improving the generated code) changes to
+ speed up the compiler in many ways (improving algorithms and fine tuning
+ code), and changes to reduce the code size of the compiler itself.</p>
-<p>Bugs fixed in the LLVM Core:</p>
+<p>More specific changes include:</p>
-<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>
+<ul>
+<li>The llvm-test framework now supports SPEC2006.</li>
+<li>LLVM now includes a <a href="GetElementPtr.html">FAQ about the
+<tt>getelementptr</tt> instruction</a>.</li>
+<li>Bugpoint now supports a new "<tt>-find-bugs</tt>" mode. This mode makes
+ bugpoint permute pass sequences to try to expose bugs due to pass
+ sequencing.</li>
+<li>The JIT now supports lazily streaming code from multiple modules at a
+ time, implicitly linking the code as it goes.</li>
+</ul>
+</div>
-<p>Bugs in the C/C++ front-end:</p>
+<!--=========================================================================-->
+<div class="doc_subsection">
+<a name="apichanges">Significant API Changes in LLVM 1.9</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">
-<p>Bugs fixed in the Sparc V9 back-end:</p>
+<p>Several significant API changes have been made. If you are maintaining
+out-of-tree code, please be aware that:</p>
-<ol>
- <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
- failure with certain indirect calls</a></li>
-</ol>
+<ul>
+<li>The ConstantSInt and ConstantUInt classes have been merged into the
+ ConstantInt class.</li>
+<li><p>As a step towards making LLVM's integer types signless, several new
+instructions have been added to LLVM. The <tt>Div</tt> instruction is now
+<tt>UDiv</tt>, <tt>SDiv</tt>, and <tt>FDiv</tt>. The <tt>Rem</tt> instruction
+is now <tt>URem</tt>, <tt>SRem</tt> and <tt>FRem</tt>. See the
+<a href="LangRef.html">Language Reference</a> for details on these new
+instructions.</p>
+<li><p><tt>ConstantBool::True</tt> and <tt>ConstantBool::False</tt> have been
+ renamed to <tt>ConstantBool::getTrue()</tt> and
+ <tt>ConstantBool::getFalse()</tt>.</p></li>
+<li>The 'analyze' tool has been merged into the 'opt' tool.</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>Intel and AMD machines running on Win32 using MinGW libraries (native)</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 in 32-bit and
+ 64-bit modes.</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>
be broken or unreliable, or are in early development. These components should
not be relied on, and bugs should not be filed against them, but they may be
useful to some people. In particular, if you would like to work on one of these
-components, please contact us on the llvmdev list.</p>
+components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
+
+<ul>
+<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
+ future release.</li>
+<li>The IA64 code generator is experimental.</li>
+<li>The ARM 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="x86-be">Known problems with the X86 back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
+ assembly that uses the X86 floating point stack</a>. See the <a
+ href="http://llvm.org/PR879">bug</a> for details on workarounds on
+ Linux.</li>
+</ul>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ppc-be">Known problems with the PowerPC back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
+implement ordered FP comparisons</a>.</li>
+<li>The 64-bit PowerPC backend is not fully stable. If you desire PPC64 support,
+ please use mainline CVS LLVM, which has several important bug fixes.</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="c-be">Known problems with the C back-end</a>
+</div>
+
+<div class="doc_text">
<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 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#int_stacksave"><tt>llvm.stacksave</tt></a> or
+<a href="LangRef.html#int_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>
+
+<li><a href="http://llvm.org/PR802">The C backend does not support inline
+ assembly code</a>.</li>
+</ul>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="alpha-be">Known problems with the Alpha back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+
+<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
+appropriate nops inserted to ensure restartability.</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="arm-be">Known problems with the ARM back-end</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+<li>The ARM backend is currently in early development stages, it is not
+ready for production use.</li>
</ul>
</div>
<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">
-<ul>
-<li>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) {
- int X[n];
- foo(X);
- }
-</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>
-</ul>
+<p>
+
+<p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
+does not currently support <a href="http://llvm.org/PR869">Link-Time
+Optimization</a> or <a href="http://llvm.org/PR870">C++ Exception Handling</a>,
+which llvm-gcc3 does.</p>
+
+<p>llvm-gcc4 does not support the <a href="http://llvm.org/PR947">GCC indirect
+goto extension</a>, but llvm-gcc3 does.</p>
+
</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>
-<li>The following Unix system functionality has not been tested and may not
-work:
- <ol>
- <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
- appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
- <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
- <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
- - These functions have not been tested.
- </ol></li>
-
<li>Although many GCC extensions are supported, some are not. In particular,
the following extensions are known to <b>not be</b> supported:
<ol>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
- <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
</ol>
Declaring that functions have no side effects or that they can never
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>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
+ <b>Supported:</b> <tt>constructor</tt>, <tt>destructor</tt>,
+ <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
+ <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noreturn</tt>,
+ <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
+ <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
- <b>Ignored:</b> <tt>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>,
- <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
- <tt>fastcall</tt>, all other target specific attributes</li>
+ <b>Unsupported:</b> <tt>alias</tt>, <tt>regparm</tt>, all other target specific
+ attributes</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
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>deprecated</tt>, <tt>dllimport</tt>, <tt>dllexport</tt>,
+ <tt>section</tt>, <tt>transparent_union</tt>, <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>vector_size</tt>, <tt>dllimport</tt>,
- <tt>dllexport</tt>, all target specific attributes.</li>
+ <tt>shared</tt>, <tt>tls_model</tt>,
+ <tt>vector_size</tt>, all target specific attributes.
+ </li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
<b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</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/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
+ <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/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>
<div class="doc_text">
-<p>For this release, the C++ front-end is considered to be fully. It has been
+<p>For this release, the C++ front-end is considered to be fully
tested and works for a number of non-trivial programs, including LLVM
itself.</p>
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">Bugs</div>
-
-<div class="doc_text">
-
-<ul>
-<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>
-
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
Notes
</div>
<div class="doc_text">
-
<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>llvm-gcc4 does not support C++ exception handling at all yet.</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
representation issues. Because we use this API, code generated by the LLVM
compilers should be binary compatible with machine code generated by other
Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
- <i>However</i>, the exception handling mechanism used by LLVM is very
+ <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
different from the model used in the Itanium ABI, so <b>exceptions will not
interact correctly</b>. </li>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="x86-be">Known problems with the X86 back-end</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
- <li>none yet</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.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
-several programs in the LLVM test suite</a></li>
-</ul>
-
-</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ppc-be">Known problems with the PowerPC back-end</a>
-</div>
-
-<div class="doc_text">
-
-<ul>
-<li>none yet</li>
-</ul>
-
-</div>
-
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="c-be">Known problems with the C 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><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_section">
<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>
<a href="http://validator.w3.org/check/referer"><img
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>
Last modified: $Date$
</address>
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