<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="_static/llvm.css" type="text/css">
- <title>LLVM 3.1 Release Notes</title>
+ <title>LLVM 3.2 Release Notes</title>
</head>
<body>
-<h1>LLVM 3.1 Release Notes</h1>
+<h1>LLVM 3.2 Release Notes</h1>
<div>
<img style="float:right" src="http://llvm.org/img/DragonSmall.png"
<ol>
<li><a href="#intro">Introduction</a></li>
<li><a href="#subproj">Sub-project Status Update</a></li>
- <li><a href="#externalproj">External Projects Using LLVM 3.1</a></li>
+ <li><a href="#externalproj">External Projects Using LLVM 3.2</a></li>
<li><a href="#whatsnew">What's New in LLVM?</a></li>
<li><a href="GettingStarted.html">Installation Instructions</a></li>
<li><a href="#knownproblems">Known Problems</a></li>
<p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
</div>
-<h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.1
+<h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.2
release.<br>
You may prefer the
-<a href="http://llvm.org/releases/3.0/docs/ReleaseNotes.html">LLVM 3.0
+<a href="http://llvm.org/releases/3.1/docs/ReleaseNotes.html">LLVM 3.1
Release Notes</a>.</h1>
<!-- *********************************************************************** -->
<div>
<p>This document contains the release notes for the LLVM Compiler
- Infrastructure, release 3.1. Here we describe the status of LLVM, including
+ Infrastructure, release 3.2. Here we describe the status of LLVM, including
major improvements from the previous release, improvements in various
- subprojects of LLVM, and some of the current users of the code.
- All LLVM releases may be downloaded from
- the <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
+ subprojects of LLVM, and some of the current users of the code. All LLVM
+ releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
+ releases web site</a>.</p>
<p>For more information about LLVM, including information about the latest
release, please check out the <a href="http://llvm.org/">main LLVM web
<div>
-<p>The LLVM 3.1 distribution currently consists of code from the core LLVM
- repository (which roughly includes the LLVM optimizers, code generators and
- supporting tools), and the Clang repository. In addition to this code, the
- LLVM Project includes other sub-projects that are in development. Here we
+<p>The LLVM 3.2 distribution currently consists of code from the core LLVM
+ repository, which roughly includes the LLVM optimizers, code generators and
+ supporting tools, and the Clang repository. In addition to this code, the
+ LLVM Project includes other sub-projects that are in development. Here we
include updates on these subprojects.</p>
<!--=========================================================================-->
production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
(32- and 64-bit), and for Darwin/ARM targets.</p>
-<p>In the LLVM 3.1 time-frame, the Clang team has made many improvements.
+<p>In the LLVM 3.2 time-frame, the Clang team has made many improvements.
Highlights include:</p>
<ul>
- <li>Greatly expanded <a href="http://clang.llvm.org/cxx_status.html">C++11
- support</a> including lambdas, initializer lists, constexpr, user-defined
- literals, and atomics.</li>
- <li>A new <a href="http://clang.llvm.org/docs/Tooling.html">tooling</a>
- library to ease building of clang-based standalone tools.</li>
- <li>Extended support for
- <a href="http://clang.llvm.org/docs/ObjectiveCLiterals.html">literals in
- Objective C</a>.</li>
+ <li>...</li>
</ul>
-<p>For more details about the changes to Clang since the 3.0 release, see the
+<p>For more details about the changes to Clang since the 3.1 release, see the
<a href="http://clang.llvm.org/docs/ReleaseNotes.html">Clang release
notes.</a></p>
Linux and OpenBSD platforms. It fully supports Ada, C, C++ and Fortran. It
has partial support for Go, Java, Obj-C and Obj-C++.</p>
-<p>The 3.1 release has the following notable changes:</p>
+<p>The 3.2 release has the following notable changes:</p>
<ul>
- <li>Partial support for gcc-4.7. Ada support is poor, but other languages work
- fairly well.</li>
-
- <li>Support for ARM processors. Some essential gcc headers that are needed to
- build DragonEgg for ARM are not installed by gcc. To work around this,
- copy the missing headers from the gcc source tree.</li>
-
- <li>Better optimization for Fortran by exploiting the fact that Fortran scalar
- arguments have 'restrict' semantics.</li>
-
- <li>Better optimization for all languages by passing information about type
- aliasing and type ranges to the LLVM optimizers.</li>
-
- <li>A regression test-suite was added.</li>
+ <li>...</li>
</ul>
</div>
target-specific hooks required by code generation and other runtime
components. For example, when compiling for a 32-bit target, converting a
double to a 64-bit unsigned integer is compiled into a runtime call to the
- "__fixunsdfdi" function. The compiler-rt library provides highly optimized
- implementations of this and other low-level routines (some are 3x faster than
- the equivalent libgcc routines).</p>
+ <code>__fixunsdfdi</code> function. The compiler-rt library provides highly
+ optimized implementations of this and other low-level routines (some are 3x
+ faster than the equivalent libgcc routines).</p>
+
+<p>The 3.2 release has the following notable changes:</p>
-<p>As of 3.1, compiler-rt includes the helper functions for atomic operations,
- allowing atomic operations on arbitrary-sized quantities to work. These
- functions follow the specification defined by gcc and are used by clang.</p>
+<ul>
+ <li>...</li>
+</ul>
</div>
expression parsing (particularly for C++) and uses the LLVM JIT for target
support.</p>
+<p>The 3.2 release has the following notable changes:</p>
+
+<ul>
+ <li>...</li>
+</ul>
+
</div>
<!--=========================================================================-->
licensed</a> under the MIT and UIUC license, allowing it to be used more
permissively.</p>
-<p>Within the LLVM 3.1 time-frame there were the following highlights:</p>
+<p>Within the LLVM 3.2 time-frame there were the following highlights:</p>
<ul>
- <li>The <code><atomic></code> header is now passing all tests, when
- compiling with clang and linking against the support code from
- compiler-rt.</li>
- <li>FreeBSD now includes libc++ as part of the base system.</li>
- <li>libc++ has been ported to Solaris and, in combination with libcxxrt and
- clang, is working with a large body of existing code.</li>
+ <li>...</li>
</ul>
</div>
of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
just-in-time compilation.</p>
-<p>In the LLVM 3.1 time-frame, VMKit has had significant improvements on both
- runtime and startup performance.</p>
+<p>The 3.2 release has the following notable changes:</p>
+
+<ul>
+ <li>...</li>
+</ul>
</div>
Work in the area of automatic SIMD and accelerator code generation was
started.</p>
-<p>Within the LLVM 3.1 time-frame there were the following highlights:</p>
+<p>Within the LLVM 3.2 time-frame there were the following highlights:</p>
<ul>
- <li>Polly became an official LLVM project</li>
- <li>Polly can be loaded directly into clang (enabled by '-O3 -mllvm -polly')</li>
- <li>An automatic scheduling optimizer (derived
- from <a href="http://pluto-compiler.sourceforge.net/">Pluto</a>) was
- integrated. It performs loop transformations to optimize for data-locality
- and parallelism. The transformations include, but are not limited to
- interchange, fusion, fission, skewing and tiling.</li>
+ <li>...</li>
</ul>
</div>
<!-- *********************************************************************** -->
<h2>
- <a name="externalproj">External Open Source Projects Using LLVM 3.1</a>
+ <a name="externalproj">External Open Source Projects Using LLVM 3.2</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>An exciting aspect of LLVM is that it is used as an enabling technology for
- a lot of other language and tools projects. This section lists some of the
- projects that have already been updated to work with LLVM 3.1.</p>
+ a lot of other language and tools projects. This section lists some of the
+ projects that have already been updated to work with LLVM 3.2.</p>
<h3>Crack</h3>
<!-- *********************************************************************** -->
<h2>
- <a name="whatsnew">What's New in LLVM 3.1?</a>
+ <a name="whatsnew">What's New in LLVM 3.2?</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>This release includes a huge number of bug fixes, performance tweaks and
- minor improvements. Some of the major improvements and new features are
+ minor improvements. Some of the major improvements and new features are
listed in this section.</p>
<!--=========================================================================-->
<div>
- <!-- Features that need text if they're finished for 3.1:
+ <!-- Features that need text if they're finished for 3.2:
ARM EHABI
combiner-aa?
strong phi elim
loop dependence analysis
CorrelatedValuePropagation
- lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
+ lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.2.
Integrated assembler on by default for arm/thumb?
-->
llvm/lib/Archive - replace with lib object?
-->
-<p>LLVM 3.1 includes several major changes and big features:</p>
+<p>LLVM 3.2 includes several major changes and big features:</p>
<ul>
- <li><a href="../tools/clang/docs/AddressSanitizer.html">AddressSanitizer</a>,
- a fast memory error detector.</li>
- <li><a href="CodeGenerator.html#machineinstrbundle">MachineInstr Bundles</a>,
- Support to model instruction bundling / packing.</li>
- <li><a href="#armintegratedassembler">ARM Integrated Assembler</a>,
- A full featured assembler and direct-to-object support for ARM.</li>
- <li><a href="#blockplacement">Basic Block Placement</a>
- Probability driven basic block placement.</li>
+ <li>...</li>
</ul>
</div>
expose new optimization opportunities:</p>
<ul>
- <li>A new type representing 16 bit <i>half</i> floating point values has
- been added.</li>
- <li>IR now supports vectors of pointers, including vector GEPs.</li>
- <li>Module flags have been introduced. They convey information about the
- module as a whole to LLVM subsystems. This is currently used to encode
- Objective C ABI information.</li>
- <li>Loads can now have range metadata attached to them to describe the
- possible values being loaded.</li>
- <li>The <tt>llvm.ctlz</tt> and <tt>llvm.cttz</tt> intrinsics now have an
- additional argument which indicates whether the behavior of the intrinsic
- is undefined on a zero input. This can be used to generate more efficient
- code on platforms that only have instructions which don't return the type
- size when counting bits in 0.</li>
+ <li>...</li>
</ul>
</div>
<div>
-<p>In addition to many minor performance tweaks and bug fixes, this
- release includes a few major enhancements and additions to the
- optimizers:</p>
+<p>In addition to many minor performance tweaks and bug fixes, this release
+ includes a few major enhancements and additions to the optimizers:</p>
<ul>
- <li>The loop unroll pass now is able to unroll loops with run-time trip counts.
- This feature is turned off by default, and is enabled with the
- <code>-unroll-runtime</code> flag.</li>
- <li>A new basic-block autovectorization pass is available. Pass
- <code>-vectorize</code> to run this pass along with some associated
- post-vectorization cleanup passes. For more information, see the EuroLLVM
- 2012 slides: <a href="http://llvm.org/devmtg/2012-04-12/Slides/Hal_Finkel.pdf">
- Autovectorization with LLVM</a>.</li>
- <li>Inline cost heuristics have been completely overhauled and now closely
- model constant propagation through call sites, disregard trivially dead
- code costs, and can model C++ STL iterator patterns.</li>
+ <li>...</li>
</ul>
</div>
<p>The LLVM Machine Code (aka MC) subsystem was created to solve a number of
problems in the realm of assembly, disassembly, object file format handling,
and a number of other related areas that CPU instruction-set level tools work
- in. For more information, please see
-
the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro
- to the LLVM MC Project Blog Post</a>.</p>
+ in. For more information, please see the
+ <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro
+ to the LLVM MC Project Blog Post</a>.</p>
<ul>
- <li>The integrated assembler can optionally emit debug information when
- assembling a </tt>.s</tt> file. It can be enabled by passing the
- <tt>-g</tt> option to <tt>llvm-mc</tt>.</li>
+ <li>...</li>
</ul>
</div>
make it run faster:</p>
<ul>
- <li>TableGen can now synthesize register classes that are only needed to
- represent combinations of constraints from instructions and sub-registers.
- The synthetic register classes inherit most of their properties form their
- closest user-defined super-class.</li>
- <li><code>MachineRegisterInfo</code> now allows the reserved registers to be
- frozen when register allocation starts. Target hooks should use the
- <code>MRI->canReserveReg(FramePtr)</code> method to avoid accidentally
- disabling frame pointer elimination during register allocation.</li>
- <li>A new kind of <code>MachineOperand</code> provides a compact
- representation of large clobber lists on call instructions. The register
- mask operand references a bit mask of preserved registers. Everything else
- is clobbered.</li>
- <li>The DWARF debug info writer gained support for emitting data for the
- <a href="SourceLevelDebugging.html#acceltable">name accelerator tables
- DWARF extension</a>. It is used by LLDB to speed up name lookup.</li>
+ <li>...</li>
</ul>
<p> We added new TableGen infrastructure to support bundling for
<h4>
<a name="blockplacement">Basic Block Placement</a>
</h4>
+
<div>
+
<p>A probability based block placement and code layout algorithm was added to
-LLVM's code generator. This layout pass supports probabilities derived from
-static heuristics as well as source code annotations such as
-<code>__builtin_expect</code>.</p>
+ LLVM's code generator. This layout pass supports probabilities derived from
+ static heuristics as well as source code annotations such as
+ <code>__builtin_expect</code>.</p>
+
</div>
<!--=========================================================================-->
<p>New features and major changes in the X86 target include:</p>
<ul>
- <li>Greatly improved support for AVX2.</li>
- <li>Lots of bug fixes and improvements for AVX1.</li>
- <li>Support for the FMA4 and XOP instruction set extensions.</li>
- <li>Call instructions use the new register mask operands for faster compile
- times and better support for different calling conventions. The old WINCALL
- instructions are no longer needed.</li>
- <li>DW2 Exception Handling is enabled on Cygwin and MinGW.</li>
- <li>Support for implicit TLS model used with MSVC runtime.</li>
+ <li>...</li>
</ul>
</div>
<p>New features of the ARM target include:</p>
<ul>
- <li>The constant island pass now supports basic block and constant pool entry
- alignments greater than 4 bytes.</li>
- <li>On Darwin, the ARM target now has a full-featured integrated assembler.
- </li>
+ <li>...</li>
</ul>
+<!--_________________________________________________________________________-->
+
<h4>
<a name="armintegratedassembler">ARM Integrated Assembler</a>
</h4>
+
<div>
+
<p>The ARM target now includes a full featured macro assembler, including
-direct-to-object module support for clang. The assembler is currently enabled
-by default for Darwin only pending testing and any additional necessary
-platform specific support for Linux.</p>
+ direct-to-object module support for clang. The assembler is currently enabled
+ by default for Darwin only pending testing and any additional necessary
+ platform specific support for Linux.</p>
<p>Full support is included for Thumb1, Thumb2 and ARM modes, along with
-subtarget and CPU specific extensions for VFP2, VFP3 and NEON.</p>
+ subtarget and CPU specific extensions for VFP2, VFP3 and NEON.</p>
<p>The assembler is Unified Syntax only (see ARM Architecural Reference Manual
-for details). While there is some, and growing, support for pre-unfied (divided)
-syntax, there are still significant gaps in that support.</p>
-</div>
+ for details). While there is some, and growing, support for pre-unfied
+ (divided) syntax, there are still significant gaps in that support.</p>
</div>
-<!--=========================================================================-->
-<h3>
-<a name="MIPS">MIPS Target Improvements</a>
-</h3>
-<div>
-New features and major changes in the MIPS target include:</p>
-
-<ul>
- <li>MIPS32 little-endian direct object code emission is functional.</li>
- <li>MIPS64 little-endian code generation is largely functional for N64 ABI in assembly printing mode with the exception of handling of long double (f128) type.</li>
- <li>Support for new instructions has been added, which includes swap-bytes
- instructions (WSBH and DSBH), floating point multiply-add/subtract and
- negative multiply-add/subtract instructions, and floating
- point load/store instructions with reg+reg addressing (LWXC1, etc.)</li>
- <li>Various fixes to improve performance have been implemented.</li>
- <li>Post-RA scheduling is now enabled at -O3.</li>
- <li>Support for soft-float code generation has been added.</li>
- <li>clang driver's support for MIPS 64-bits targets.</li>
- <li>Support for MIPS floating point ABI option in clang driver.</li>
-</ul>
</div>
<!--=========================================================================-->
<h3>
-<a name="PTX">PTX Target Improvements</a>
+<a name="MIPS">MIPS Target Improvements</a>
</h3>
<div>
-<p>An outstanding conditional inversion bug was fixed in this release.</p>
+<p>New features and major changes in the MIPS target include:</p>
-<p><b>NOTE</b>: LLVM 3.1 marks the last release of the PTX back-end, in its
- current form. The back-end is currently being replaced by the NVPTX
- back-end, currently in SVN ToT.</p>
+<ul>
+ <li>...</li>
+</ul>
</div>
<div>
<ul>
- <li>Support for Qualcomm's Hexagon VLIW processor has been added.</li>
+ <li>...</li>
</ul>
</div>
<div>
<p>If you're already an LLVM user or developer with out-of-tree changes based on
- LLVM 3.1, this section lists some "gotchas" that you may run into upgrading
+ LLVM 3.2, this section lists some "gotchas" that you may run into upgrading
from the previous release.</p>
<ul>
- <li>LLVM's build system now requires a python 2 interpreter to be present at
- build time. A perl interpreter is no longer required.</li>
- <li>The C backend has been removed. It had numerous problems, to the point of
- not being able to compile any nontrivial program.</li>
- <li>The Alpha, Blackfin and SystemZ targets have been removed due to lack of
- maintenance.</li>
- <li>LLVM 3.1 removes support for reading LLVM 2.9 bitcode files. Going
- forward, we aim for all future versions of LLVM to read bitcode files and
- <tt>.ll</tt> files produced by LLVM 3.0 and later.</li>
- <li>The <tt>unwind</tt> instruction is now gone. With the introduction of the
- new exception handling system in LLVM 3.0, the <tt>unwind</tt> instruction
- became obsolete.</li>
- <li>LLVM 3.0 and earlier automatically added the returns_twice fo functions
- like setjmp based on the name. This functionality was removed in 3.1.
- This affects Clang users, if -ffreestanding is used.</li>
+ <li>...</li>
</ul>
</div>
LLVM API changes are:</p>
<ul>
- <li>Target specific options have been moved from global variables to members
- on the new <code>TargetOptions</code> class, which is local to each
- <code>TargetMachine</code>. As a consequence, the associated flags will
- no longer be accepted by <tt>clang -mllvm</tt>. This includes:
-<ul>
-<li><code>llvm::PrintMachineCode</code></li>
-<li><code>llvm::NoFramePointerElim</code></li>
-<li><code>llvm::NoFramePointerElimNonLeaf</code></li>
-<li><code>llvm::DisableFramePointerElim(const MachineFunction &)</code></li>
-<li><code>llvm::LessPreciseFPMADOption</code></li>
-<li><code>llvm::LessPrecideFPMAD()</code></li>
-<li><code>llvm::NoExcessFPPrecision</code></li>
-<li><code>llvm::UnsafeFPMath</code></li>
-<li><code>llvm::NoInfsFPMath</code></li>
-<li><code>llvm::NoNaNsFPMath</code></li>
-<li><code>llvm::HonorSignDependentRoundingFPMathOption</code></li>
-<li><code>llvm::HonorSignDependentRoundingFPMath()</code></li>
-<li><code>llvm::UseSoftFloat</code></li>
-<li><code>llvm::FloatABIType</code></li>
-<li><code>llvm::NoZerosInBSS</code></li>
-<li><code>llvm::JITExceptionHandling</code></li>
-<li><code>llvm::JITEmitDebugInfo</code></li>
-<li><code>llvm::JITEmitDebugInfoToDisk</code></li>
-<li><code>llvm::GuaranteedTailCallOpt</code></li>
-<li><code>llvm::StackAlignmentOverride</code></li>
-<li><code>llvm::RealignStack</code></li>
-<li><code>llvm::DisableJumpTables</code></li>
-<li><code>llvm::EnableFastISel</code></li>
-<li><code>llvm::getTrapFunctionName()</code></li>
-<li><code>llvm::EnableSegmentedStacks</code></li>
-</ul></li>
-
- <li>The <code>MDBuilder</code> class has been added to simplify the creation
- of metadata.</li>
+ <li>...</li>
</ul>
</div>
<p>In addition, some tools have changed in this release. Some of the changes
are:</p>
-
<ul>
- <li><tt>llvm-stress</tt> is a command line tool for generating random
- <tt>.ll</tt> files to fuzz different LLVM components. </li>
- <li>The <tt>llvm-ld</tt> tool has been removed. The clang driver provides a
- more reliable solution for turning a set of bitcode files into a binary.
- To merge bitcode files <tt>llvm-link</tt> can be used instead.</li>
+ <li>...</li>
</ul>
</div>
<div>
<p>Officially supported Python bindings have been added! Feature support is far
-from complete. The current bindings support interfaces to:</p>
+ from complete. The current bindings support interfaces to:</p>
+
<ul>
- <li>Object File Interface</li>
- <li>Disassembler</li>
+ <li>...</li>
</ul>
-<p>Using the Object File Interface, it is possible to inspect binary object files.
-Think of it as a Python version of readelf or llvm-objdump.</p>
-
-<p>Support for additional features is currently being developed by community
-contributors. If you are interested in shaping the direction of the Python
-bindings, please express your intent on IRC or the developers list.</p>
-
</div>
</div>
<p>LLVM is generally a production quality compiler, and is used by a broad range
of applications and shipping in many products. That said, not every
subsystem is as mature as the aggregate, particularly the more obscure
- targets. If you run into a problem, please check the <a
- href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
- there isn't already one or ask on the <a
- href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev
- list</a>.</p>
+ targets. If you run into a problem, please check
+ the <a href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
+ there isn't already one or ask on
+ the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev
+ list</a>.</p>
<p>Known problem areas include:</p>
<li>The CellSPU, MSP430, PTX and XCore backends are experimental.</li>
<li>The integrated assembler, disassembler, and JIT is not supported by
- several targets. If an integrated assembler is not supported, then a
+ several targets. If an integrated assembler is not supported, then a
system assembler is required. For more details, see the <a
href="CodeGenerator.html#targetfeatures">Target Features Matrix</a>.
</li>
projects / oota-llvm.git / commitdiff