mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-12 17:32:19 +00:00
Strip out 2.3 info, make space for 2.4 info. I'd appreciate it if
various component owners could look through and update their areas in the known-problems section. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57376 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
ce91ec285d
commit
857fb1309f
@ -1,15 +1,14 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 2.3 Release Notes</title>
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<title>LLVM 2.4 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">LLVM 2.3 Release Notes</div>
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<div class="doc_title">LLVM 2.4 Release Notes</div>
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<ol>
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<li><a href="#intro">Introduction</a></li>
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@ -36,7 +35,7 @@
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<div class="doc_text">
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<p>This document contains the release notes for the LLVM compiler
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infrastructure, release 2.3. Here we describe the status of LLVM, including
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infrastructure, release 2.4. Here we describe the status of LLVM, including
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major improvements from the previous release and any known problems. All LLVM
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releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
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releases web site</a>.</p>
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@ -62,12 +61,12 @@ current one. To see the release notes for a specific releases, please see the
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<div class="doc_text">
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<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
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It includes a large number of features and refinements from LLVM 2.2.</p>
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<p>This is the fifteenth public release of the LLVM Compiler Infrastructure.
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It includes a large number of features and refinements from LLVM 2.3.</p>
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|
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</div>
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||||
|
||||
<!-- Unfinished features in 2.3:
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<!-- Unfinished features in 2.4:
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Machine LICM
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Machine Sinking
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LegalizeDAGTypes
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@ -75,47 +74,17 @@ It includes a large number of features and refinements from LLVM 2.2.</p>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="changes">Major Changes in LLVM 2.3</a>
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<a name="changes">Major Changes in LLVM 2.4</a>
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</div>
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<div class="doc_text">
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<p>LLVM 2.3 no longer supports llvm-gcc 4.0, it has been replaced with
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llvm-gcc 4.2.</p>
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|
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<p>LLVM 2.3 no longer includes the <tt>llvm-upgrade</tt> tool. It was useful
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for upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a
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previous LLVM release to do this. One nice impact of this is that the LLVM
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regression test suite no longer depends on llvm-upgrade, which makes it run
|
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faster.</p>
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|
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<p>The <tt>llvm2cpp</tt> tool has been folded into llc, use
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<tt>llc -march=cpp</tt> instead of <tt>llvm2cpp</tt>.</p>
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<p>....</p>
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|
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<p>LLVM API Changes:</p>
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|
||||
<ul>
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<li>Several core LLVM IR classes have migrated to use the
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'<tt>FOOCLASS::Create(...)</tt>' pattern instead of '<tt>new
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FOOCLASS(...)</tt>' (e.g. where FOOCLASS=<tt>BasicBlock</tt>). We hope to
|
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standardize on <tt>FOOCLASS::Create</tt> for all IR classes in the future,
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but not all of them have been moved over yet.</li>
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<li>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
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<a href="http://llvm.org/doxygen/classllvm_1_1IRBuilder.html">IRBuilder</a>.
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</li>
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<li>MRegisterInfo was renamed to
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<a href="http://llvm.org/doxygen/classllvm_1_1TargetRegisterInfo.html">
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TargetRegisterInfo</a>.</li>
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<li>The MappedFile class is gone, please use
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<a href="http://llvm.org/doxygen/classllvm_1_1MemoryBuffer.html">
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MemoryBuffer</a> instead.</li>
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<li>The '<tt>-enable-eh</tt>' flag to llc has been removed. Now code should
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encode whether it is safe to omit unwind information for a function by
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tagging the Function object with the '<tt>nounwind</tt>' attribute.</li>
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<li>The ConstantFP::get method that uses APFloat now takes one argument
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instead of two. The type argument has been removed, and the type is
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now inferred from the size of the given APFloat value.</li>
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<li>....</li>
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</ul>
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</div>
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@ -126,12 +95,12 @@ It includes a large number of features and refinements from LLVM 2.2.</p>
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<div class="doc_text">
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<p>
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The core LLVM 2.3 distribution currently consists of code from the core LLVM
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The core LLVM 2.4 distribution currently consists of code from the core LLVM
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repository (which roughly contains the LLVM optimizer, code generators and
|
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supporting tools) and the llvm-gcc repository. In addition to this code, the
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||||
LLVM Project includes other sub-projects that are in development. The two which
|
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are the most actively developed are the new <a href="#vmkit">vmkit Project</a>
|
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and the <a href="#clang">Clang Project</a>.
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are the most actively developed are the <a href="#clang">Clang Project</a> and
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<a href="#vmkit">vmkit Project</a>.
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</p>
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</div>
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@ -142,28 +111,11 @@ and the <a href="#clang">Clang Project</a>.
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<div class="doc_text">
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<p>
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The "vmkit" project is a new addition to the LLVM family. It is an
|
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implementation of a JVM and a CLI Virtual Machines (Microsoft .NET is an
|
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The <a href="http://vmkit.llvm.org/">"vmkit" project</a> is an implementation of
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a JVM and a CLI Virtual Machines (Microsoft .NET is an
|
||||
implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
|
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|
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<p>The JVM, called JnJVM, executes real-world applications such as Apache
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projects (e.g. Felix and Tomcat) and the SpecJVM98 benchmark. It uses the GNU
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Classpath project for the base classes. The CLI implementation, called N3, is
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its in early stages but can execute simple applications and the "pnetmark"
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benchmark. It uses the pnetlib project as its core library.</p>
|
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|
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<p>The 'vmkit' VMs compare in performance with industrial and top open-source
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VMs on scientific applications. Besides the JIT, the VMs use many features of
|
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the LLVM framework, including the standard set of optimizations, atomic
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operations, custom function provider and memory manager for JITed methods, and
|
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specific virtual machine optimizations. vmkit is not an official part of LLVM
|
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2.3 release. It is publicly available under the LLVM license and can be
|
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downloaded from:
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</p>
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<div class="doc_code">
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<pre>svn co http://llvm.org/svn/llvm-project/vmkit/trunk vmkit</pre>
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</div>
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<p>...</p>
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|
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</div>
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@ -182,12 +134,12 @@ generation support is far enough along to build many C applications. While not
|
||||
yet production quality, it is progressing very nicely. In addition, C++
|
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front-end work has started to make significant progress.</p>
|
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|
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<p>At this point, Clang is most useful if you are interested in source-to-source
|
||||
transformations (such as refactoring) and other source-level tools for C and
|
||||
Objective-C. Clang now also includes tools for turning C code into pretty HTML,
|
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and includes a new <a href="http://clang.llvm.org/StaticAnalysis.html">static
|
||||
analysis tool</a> in development. This tool focuses on automatically finding
|
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bugs in C and Objective-C code.</p>
|
||||
<p>Codegen progress/state
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<a href="http://clang.llvm.org/StaticAnalysis.html">static analysis tool</a>
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||||
</p>
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||||
|
||||
</div>
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||||
|
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@ -200,7 +152,7 @@ bugs in C and Objective-C code.</p>
|
||||
|
||||
<div class="doc_text">
|
||||
|
||||
<p>LLVM 2.3 includes a huge number of bug fixes, performance tweaks and minor
|
||||
<p>LLVM 2.4 includes a huge number of bug fixes, performance tweaks and minor
|
||||
improvements. Some of the major improvements and new features are listed in
|
||||
this section.
|
||||
</p>
|
||||
@ -213,52 +165,18 @@ this section.
|
||||
|
||||
<div class="doc_text">
|
||||
|
||||
<p>LLVM 2.3 includes several major new capabilities:</p>
|
||||
<p>LLVM 2.4 includes several major new capabilities:</p>
|
||||
|
||||
<ul>
|
||||
<li><p>The biggest change in LLVM 2.3 is Multiple Return Value (MRV) support.
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||||
MRVs allow LLVM IR to directly represent functions that return multiple
|
||||
values without having to pass them "by reference" in the LLVM IR. This
|
||||
allows a front-end to generate more efficient code, as MRVs are generally
|
||||
returned in registers if a target supports them. See the <a
|
||||
href="LangRef.html#i_getresult">LLVM IR Reference</a> for more details.</p>
|
||||
<li>
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||||
<p>MRVs got generalized to FCAs.</p>
|
||||
</li>
|
||||
|
||||
<p>MRVs are fully supported in the LLVM IR, but are not yet fully supported in
|
||||
on all targets. However, it is generally safe to return up to 2 values from
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||||
a function: most targets should be able to handle at least that. MRV
|
||||
support is a critical requirement for X86-64 ABI support, as X86-64 requires
|
||||
the ability to return multiple registers from functions, and we use MRVs to
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||||
accomplish this in a direct way.</p></li>
|
||||
<li><p>fast isel, -O0 compile times</p></li>
|
||||
|
||||
<li><p>LLVM 2.3 includes a complete reimplementation of the "<tt>llvmc</tt>"
|
||||
tool. It is designed to overcome several problems with the original
|
||||
<tt>llvmc</tt> and to provide a superset of the features of the
|
||||
'<tt>gcc</tt>' driver.</p>
|
||||
<li><p>Attrs changes?</p></li>
|
||||
|
||||
<p>The main features of <tt>llvmc2</tt> are:
|
||||
<ul>
|
||||
<li>Extended handling of command line options and smart rules for
|
||||
dispatching them to different tools.</li>
|
||||
<li>Flexible (and extensible) rules for defining different tools.</li>
|
||||
<li>The different intermediate steps performed by tools are represented
|
||||
as edges in the abstract graph.</li>
|
||||
<li>The 'language' for driver behavior definition is tablegen and thus
|
||||
it's relatively easy to add new features.</li>
|
||||
<li>The definition of driver is transformed into set of C++ classes, thus
|
||||
no runtime interpretation is needed.</li>
|
||||
</ul>
|
||||
</li>
|
||||
|
||||
<li><p>LLVM 2.3 includes a completely rewritten interface for <a
|
||||
href="LinkTimeOptimization.html">Link Time Optimization</a>. This interface
|
||||
is written in C, which allows for easier integration with C code bases, and
|
||||
incorporates improvements we learned about from the first incarnation of the
|
||||
interface.</p></li>
|
||||
|
||||
<li><p>The <a href="tutorial/LangImpl1.html">Kaleidoscope tutorial</a> now
|
||||
includes a "port" of the tutorial that <a
|
||||
href="tutorial/OCamlLangImpl1.html">uses the Ocaml bindings</a> to implement
|
||||
the Kaleidoscope language.</p></li>
|
||||
<li><p>...</p></li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -272,19 +190,12 @@ this section.
|
||||
|
||||
<div class="doc_text">
|
||||
|
||||
<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end, and includes support
|
||||
<p>LLVM 2.4 fully supports the llvm-gcc 4.2 front-end, and includes support
|
||||
for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
|
||||
|
||||
<p>
|
||||
<ul>
|
||||
<li>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
|
||||
front-end. Objective-C now works very well on Mac OS/X.</li>
|
||||
|
||||
<li>Fortran <tt>EQUIVALENCE</tt>s are now supported by the gfortran
|
||||
front-end.</li>
|
||||
|
||||
<li>llvm-gcc 4.2 includes many other fixes which improve conformance with the
|
||||
relevant parts of the GCC testsuite.</li>
|
||||
<li>...</li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -301,17 +212,7 @@ relevant parts of the GCC testsuite.</li>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>LLVM IR now directly represents "common" linkage, instead of representing it
|
||||
as a form of weak linkage.</li>
|
||||
|
||||
<li>LLVM IR now has support for atomic operations, and this functionality can be
|
||||
accessed through the llvm-gcc "<tt>__sync_synchronize</tt>",
|
||||
"<tt>__sync_val_compare_and_swap</tt>", and related builtins. Support for
|
||||
atomics are available in the Alpha, X86, X86-64, and PowerPC backends.</li>
|
||||
|
||||
<li>The C and Ocaml bindings have extended to cover pass managers, several
|
||||
transformation passes, iteration over the LLVM IR, target data, and parameter
|
||||
attribute lists.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -324,64 +225,11 @@ attribute lists.</li>
|
||||
<div class="doc_text">
|
||||
|
||||
<p>In addition to a huge array of bug fixes and minor performance tweaks, the
|
||||
LLVM 2.3 optimizers support a few major enhancements:</p>
|
||||
LLVM 2.4 optimizers support a few major enhancements:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li><p>Loop index set splitting on by default.
|
||||
This transformation hoists conditions from loop bodies and reduces a loop's
|
||||
iteration space to improve performance. For example,</p>
|
||||
|
||||
<div class="doc_code">
|
||||
<pre>
|
||||
for (i = LB; i < UB; ++i)
|
||||
if (i <= NV)
|
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LOOP_BODY
|
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</pre>
|
||||
</div>
|
||||
|
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<p>is transformed into:</p>
|
||||
|
||||
<p><div class="doc_code">
|
||||
<pre>
|
||||
NUB = min(NV+1, UB)
|
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for (i = LB; i < NUB; ++i)
|
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LOOP_BODY
|
||||
</pre>
|
||||
</div>
|
||||
</p>
|
||||
</li>
|
||||
|
||||
<li>LLVM now includes a new <tt>memcpy</tt> optimization pass which removes
|
||||
dead <tt>memcpy</tt> calls, unneeded copies of aggregates, and performs
|
||||
return slot optimization. The LLVM optimizer now notices long sequences of
|
||||
consecutive stores and merges them into <tt>memcpy</tt>'s where profitable.</li>
|
||||
|
||||
<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
|
||||
<tt>memset</tt> is now more aggressive.</li>
|
||||
|
||||
<li>The Aggressive Dead Code Elimination (ADCE) optimization has been rewritten
|
||||
to make it both faster and safer in the presence of code containing infinite
|
||||
loops. Some of its prior functionality has been factored out into the loop
|
||||
deletion pass, which <em>is</em> safe for infinite loops. The new ADCE pass is
|
||||
no longer based on control dependence, making it run faster.</li>
|
||||
|
||||
<li>The 'SimplifyLibCalls' pass, which optimizes calls to libc and libm
|
||||
functions for C-based languages, has been rewritten to be a FunctionPass
|
||||
instead a ModulePass. This allows it to be run more often and to be
|
||||
included at -O1 in llvm-gcc. It was also extended to include more
|
||||
optimizations and several corner case bugs were fixed.</li>
|
||||
|
||||
<li>LLVM now includes a simple 'Jump Threading' pass, which attempts to simplify
|
||||
conditional branches using information about predecessor blocks, simplifying
|
||||
the control flow graph. This pass is pretty basic at this point, but
|
||||
catches some important cases and provides a foundation to build on.</li>
|
||||
|
||||
<li>Several corner case bugs which could lead to deleting volatile memory
|
||||
accesses have been fixed.</li>
|
||||
|
||||
<li>Several optimizations have been sped up, leading to faster code generation
|
||||
with the same code quality.</li>
|
||||
<li>.</li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -399,45 +247,9 @@ which allows us to implement more aggressive algorithms and make it run
|
||||
faster:</p>
|
||||
|
||||
<ul>
|
||||
<li>The code generator now has support for carrying information about memory
|
||||
references throughout the entire code generation process, via the
|
||||
<a href="http://llvm.org/doxygen/classllvm_1_1MachineMemOperand.html">
|
||||
MachineMemOperand</a> class. In the future this will be used to improve
|
||||
both pre-pass and post-pass scheduling, and to improve compiler-debugging
|
||||
output.</li>
|
||||
<li>Selection dag speedups</li>
|
||||
<li>...</li>
|
||||
|
||||
<li>The target-independent code generator infrastructure now uses LLVM's
|
||||
<a href="http://llvm.org/doxygen/classllvm_1_1APInt.html">APInt</a>
|
||||
class to handle integer values, which allows it to support integer types
|
||||
larger than 64 bits (for example i128). Note that support for such types is
|
||||
also dependent on target-specific support. Use of APInt is also a step
|
||||
toward support for non-power-of-2 integer sizes.</li>
|
||||
|
||||
<li>LLVM 2.3 includes several compile time speedups for code with large basic
|
||||
blocks, particularly in the instruction selection phase, register
|
||||
allocation, scheduling, and tail merging/jump threading.</li>
|
||||
|
||||
<li>LLVM 2.3 includes several improvements which make llc's
|
||||
<tt>--view-sunit-dags</tt> visualization of scheduling dependency graphs
|
||||
easier to understand.</li>
|
||||
|
||||
<li>The code generator allows targets to write patterns that generate subreg
|
||||
references directly in .td files now.</li>
|
||||
|
||||
<li><tt>memcpy</tt> lowering in the backend is more aggressive, particularly for
|
||||
<tt>memcpy</tt> calls introduced by the code generator when handling
|
||||
pass-by-value structure argument copies.</li>
|
||||
|
||||
<li>Inline assembly with multiple register results now returns those results
|
||||
directly in the appropriate registers, rather than going through memory.
|
||||
Inline assembly that uses constraints like "ir" with immediates now use the
|
||||
'i' form when possible instead of always loading the value in a register.
|
||||
This saves an instruction and reduces register use.</li>
|
||||
|
||||
<li>Added support for PIC/GOT style <a
|
||||
href="CodeGenerator.html#tailcallopt">tail calls</a> on X86/32 and initial
|
||||
support for tail calls on PowerPC 32 (it may also work on PowerPC 64 but is
|
||||
not thoroughly tested).</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -453,48 +265,7 @@ faster:</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
|
||||
area of passing and returning structures by value. llvm-gcc compiled code
|
||||
now interoperates very well on X86-64 systems with other compilers.</li>
|
||||
|
||||
<li>Support for Win64 was added. This includes code generation itself, JIT
|
||||
support, and necessary changes to llvm-gcc.</li>
|
||||
|
||||
<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
|
||||
the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins. Various
|
||||
generic vector operations (insert/extract/shuffle) are much more efficient
|
||||
when SSE 4.1 is enabled. The JIT automatically takes advantage of these
|
||||
instructions, but llvm-gcc must be explicitly told to use them, e.g. with
|
||||
<tt>-march=penryn</tt>.</li>
|
||||
|
||||
<li>The X86 backend now does a number of optimizations that aim to avoid
|
||||
converting numbers back and forth from SSE registers to the X87 floating
|
||||
point stack. This is important because most X86 ABIs require return values
|
||||
to be on the X87 Floating Point stack, but most CPUs prefer computation in
|
||||
the SSE units.</li>
|
||||
|
||||
<li>The X86 backend supports stack realignment, which is particularly useful for
|
||||
vector code on OS's without 16-byte aligned stacks, such as Linux and
|
||||
Windows.</li>
|
||||
|
||||
<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
|
||||
functions to be tagged as passing floating point values in SSE
|
||||
registers.</li>
|
||||
|
||||
<li>Trampolines (taking the address of a nested function) now work on
|
||||
Linux/X86-64.</li>
|
||||
|
||||
<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
|
||||
instructions instead of being ignored.</li>
|
||||
|
||||
<li>128-bit integers are now supported on X86-64 targets. This can be used
|
||||
through <tt>__attribute__((TImode))</tt> in llvm-gcc.</li>
|
||||
|
||||
<li>The register allocator can now rematerialize PIC-base computations, which is
|
||||
an important optimization for register use.</li>
|
||||
|
||||
<li>The "t" and "f" inline assembly constraints for the X87 floating point stack
|
||||
now work. However, the "u" constraint is still not fully supported.</li>
|
||||
<li>...</li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -510,9 +281,7 @@ faster:</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>The LLVM C backend now supports vector code.</li>
|
||||
<li>The Cell SPU backend includes a number of improvements. It generates better
|
||||
code and its stability/completeness is improving.</li>
|
||||
<li>....</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -529,10 +298,7 @@ faster:</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>LLVM now builds with GCC 4.3.</li>
|
||||
<li>Bugpoint now supports running custom scripts (with the <tt>-run-custom</tt>
|
||||
option) to determine how to execute the command and whether it is making
|
||||
forward process.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user