[llvm-commits] CVS: llvm/docs/ReleaseNotes.html
Chris Lattner
lattner at cs.uiuc.edu
Tue Aug 8 10:27:42 PDT 2006
Changes in directory llvm/docs:
ReleaseNotes.html updated: 1.358 -> 1.359
---
Log message:
First draft of the llvm 1.8 release notes.
---
Diffs of the changes: (+77 -162)
ReleaseNotes.html | 239 +++++++++++++++++-------------------------------------
1 files changed, 77 insertions(+), 162 deletions(-)
Index: llvm/docs/ReleaseNotes.html
diff -u llvm/docs/ReleaseNotes.html:1.358 llvm/docs/ReleaseNotes.html:1.359
--- llvm/docs/ReleaseNotes.html:1.358 Wed Apr 19 23:24:28 2006
+++ llvm/docs/ReleaseNotes.html Tue Aug 8 12:27:28 2006
@@ -4,11 +4,11 @@
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 1.7 Release Notes</title>
+ <title>LLVM 1.8 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 1.7 Release Notes</div>
+<div class="doc_title">LLVM 1.8 Release Notes</div>
<ol>
<li><a href="#intro">Introduction</a></li>
@@ -32,9 +32,10 @@
<div class="doc_text">
<p>This document contains the release notes for the LLVM compiler
-infrastructure, release 1.7. Here we describe the status of LLVM, including any
+infrastructure, release 1.8. Here we describe the status of LLVM, including any
known problems and major improvements from the previous release. The most
-up-to-date version of this document can be found on the <a
+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>
@@ -62,38 +63,30 @@
<p>This is the eighth public release of the LLVM Compiler Infrastructure. This
release incorporates a large number of enhancements and new features,
-including vector support (Intel SSE and Altivec), a new GCC4.0-based
-C/C++ front-end, Objective C/C++ support, inline assembly support, and many
-other big features.
+including DWARF debugging support (C and C++ on Darwin/PPC), improved inline
+assembly support, a new <a href="http://llvm.org/nightlytest/">nightly
+tester</a>, llvm-config enhancments, many bugs
+fixed, and performance and compile time improvements.
</p>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="newfeatures">New Features in LLVM 1.7</a>
+<a name="newfeatures">New Features in LLVM 1.8</a>
</div>
<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="llvmgcc4">GCC4.0-based llvm-gcc
-front-end</a></div>
+<div class="doc_subsubsection"><a name="dwarf">DWARF debugging
+support </a></div>
<div class="doc_text">
-<p>LLVM 1.7 includes a brand new llvm-gcc, based on GCC 4.0.1. This version
-of llvm-gcc solves many serious long-standing problems with llvm-gcc, including
-all of those blocked by the <a href="http://llvm.org/PR498">llvm-gcc 4 meta
-bug</a>. In addition, llvm-gcc4 implements support for many new features,
-including GCC inline assembly, generic vector support, SSE and Altivec
-intrinsics, and several new GCC attributes. Finally, llvm-gcc4 is
-significantly faster than llvm-gcc3, respects -O options, its -c/-S options
-correspond to GCC's (they emit native code), supports Objective C/C++, and
-it has debugging support well underway.</p>
-
-<p>If you can use it, llvm-gcc4 offers significant new functionality, and we
-hope that it will replace llvm-gcc3 completely in a future release.
-Unfortunately, it does not currently support C++ exception handling at all, and
-it only works on Apple Mac OS/X machines with X86 or PowerPC processors.
+<p>The llvm-gcc4 C front-end now generates debugging info for C and C++. This
+information is propagated through the compiler and the code generator can
+currently produce DWARF debugging information from it. DWARF is a standard
+debugging format used on many platforms, but currently LLVM only includes
+target support for Mac OS X targets for the 1.8 release.
</p>
</div>
@@ -104,174 +97,96 @@
<div class="doc_text">
-<p>The LLVM IR and llvm-gcc4 front-end now fully support arbitrary GCC <a
-href="LangRef.html#inlineasm">inline assembly</a>. The LLVM X86 and PowerPC
-code generators have initial support for it,
-being able to compile basic statements, but are missing some features. Please
-report any inline asm statements that crash the compiler or that are miscompiled
-as bugs.</p>
+<p>Inline assembly support is substantially improved in LLVM 1.8 over LLVM 1.7.
+Many unsupported features are now supported, and inline asm support in the X86
+backend is far better. llvm-gcc4 now supports global register variables as
+well.</p>
</div>
<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="newsparc">New SPARC backend</a></div>
+<div class="doc_subsubsection"><a name="loopopt">Loop Optimizer Improvements</a></div>
<div class="doc_text">
-<p>LLVM 1.7 includes a new, fully functional, SPARC backend built in the
-target-independent code generator. This SPARC backend includes support for
-SPARC V8 and SPARC V9 subtargets (controlling whether V9 features can be used),
-and targets the 32-bit SPARC ABI.</p>
-
-<p>The LLVM 1.7 release is the last release that will include the LLVM "SparcV9"
-backend, which was the very first LLVM native code generator. It will
-be removed in LLVM 1.8, being replaced with the new SPARC backend.</p>
+<p>The Loop Optimizer pass now used "Loop-Closed SSA Form", which makes it
+easier to update SSA form as loop transformations change the code. An
+immediate benefit of this is that the loop unswitching pass can now unswitch
+loops in more cases.
+</p>
</div>
<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="genvector">Generic Vector Support
+<div class="doc_subsubsection"><a name="jumptab">Jump Table Support for Switches
</a></div>
<div class="doc_text">
-<p>LLVM now includes significantly extended support for SIMD vectors in its
-core instruction set. It now includes three new instructions for manipulating
-vectors: <a href="LangRef.html#i_extractelement"><tt>extractelement</tt></a>,
-<a href="LangRef.html#i_insertelement"><tt>insertelement</tt></a>, and
-<a href="LangRef.html#i_shufflevector"><tt>shufflevector</tt></a>. Further,
-many bugs in vector handling have been fixed, and vectors are now supported by
-the target-independent code generator. For example, if a vector operation is
-not supported by a particular target, it will be correctly broken down and
-executed as scalar operations.</p>
+<p>The code generator now lowers switch statements to jump tables, providing
+significant performance boosts for applications (e.g. interpreters) whose
+performance is highly correlated to switch statement performance.</p>
-<p>Because llvm-gcc3 does not support GCC generic vectors or vector intrinsics,
-llvm-gcc4 must be used.</p>
</div>
-
<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="ssealtivec">Intel SSE and PowerPC
-Altivec support
+<div class="doc_subsubsection"><a name="jitrelease">Deallocation of JIT'd
+Machine Code
</a></div>
<div class="doc_text">
-<p>The LLVM X86 backend now supports Intel SSE 1, 2, and 3, and now uses scalar
-SSE operations to implement scalar floating point math when the target supports
-SSE1 (for floats) or SSE2 (for doubles). Vector SSE instructions are generated
-by llvm-gcc4 when the generic vector mechanism or specific SSE intrinsics are
-used.
-</p>
-
-<p>The LLVM PowerPC backend now supports the Altivec instruction set, including
-both GCC -maltivec and -faltivec modes. Altivec instructions are generated
-by llvm-gcc4 when the generic vector mechanism or specific Altivec intrinsics
-are used.
+<p>The LLVM JIT now allows clients to deallocate machine code JIT'd to its code
+buffer. This is important for long living applications that depend on the JIT.
</p>
</div>
<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="optimizernew">Optimizer
-Improvements</a></div>
+<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
<div class="doc_text">
-<ul>
-<li>The Loop Unswitching pass (<tt>-loop-unswitch</tt>) has had several bugs
- fixed, has several new features, and is enabled by default in llvmgcc3
- now.</li>
-<li>The Loop Strength Reduction pass (<tt>-loop-reduce</tt>) is now enabled for
- the X86 and Alpha backends.</li>
-<li>The Instruction Combining pass (<tt>-instcombine</tt>) now includes a
- framework and implementation for simplifying code based on whether computed
- bits are demanded or not.</li>
-<li>The Scalar Replacement of Aggregates pass (<tt>-scalarrepl</tt>) can now
- promote simple unions to registers.</li>
-<li>The Reassociation pass (<tt>-reassociate</tt>) can now
- factor expressions, e.g. turning "A*A+A*B" into "A*(A+B)".</li>
-<li>Several LLVM passes are <a href="http://llvm.org/PR681">significantly
-faster</a>.</li>
-</ul>
-</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="codgennew">Code Generator
-Improvements</a></div>
+<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>More specific changes include:</p>
+
+<ul>
+<li>LLVM 1.8 includes an initial ARM backend. This backend is in early
+ development stages.</li>
+<li>LLVM 1.8 now includes significantly better support for mingw and
+ cygwin.</li>
+<li>The <a href="CommandGuide/html/llvm-config.html">llvm-config</a> tool is
+ now built by default and has several new features.</li>
+<li>The X86 and PPC backends now use the correct platform ABI for passing
+ vectors as arguments to functions.</li>
+<li>The X86 backend now includes support for the Microsoft ML assembler
+ ("MASM").</li>
+<li>The PowerPC backend now pattern matches the 'rlwimi' instruction more
+ aggressively.</li>
+<li>Most of LLVM is now built with "-pedantic", ensuring better portability
+ to more C++ Compilers.</li>
+<li>The PowerPC backend now includes initial 64-bit support. The JIT is not
+ complete, and the static compiler has a couple of known bugs, but support
+ is mostly in place. LLVM 1.9 will include completed PPC-64 support. </li>
-<div class="doc_text">
-<ul>
-<li>LLVM has a new prepass (before register allocation) list scheduler, which
- supports bottom-up and top-down scheduling, pluggable priority functions and
- pluggable hazard recognizers. The X86 backend uses this to reduce register
- pressure and RISC targets schedule based on operation latency.</li>
-<li>The tblgen-based target description framework introduced in LLVM 1.6 has
- several new features, useful for targets that can fold loads and stores into
- operations, and features that make the .td files more expressive.</li>
-<li>The instruction selector is significantly faster in 1.7 than in 1.6.</li>
-<li>The X86, Alpha and Itanium backends use new DAG-DAG instruction selectors,
- making them easier to maintain and generate slightly better code.</li>
-<li>The X86 backend now supports generation of Scalar SSE code for scalar FP
- expressions. LLVM provides significantly better performance with Scalar SSE
- instructions than it does with the Intel floating point stack
- instructions.</li>
-<li>The Itanium backend now has a bundling pass, which improves performance
- by ~10% and reduces code size (previously it unconditionally inserted a stop
- bit after every instruction).</li>
</ul>
</div>
-<!--_________________________________________________________________________-->
-<div class="doc_subsubsection"><a name="othernew">Other New Features</a></div>
-
-<div class="doc_text">
-<ul>
-<li>The Mac OS/X PowerPC and X86 backends now have initial support for
- Darwin DWARF
- debugging information, however, debug info generation has been disabled for
- the 1.7 release in llvmgcc4.</li>
-<li>LLVM includes the new <a href="docs/CommandGuide/html/llvm-config.html">
- llvm-config</a> utility, which makes it easier to build and link programs
- against the LLVM libraries when not using the LLVM makefiles.</li>
-<li>LLVM now supports first class global ctor/dtor initialization lists, no
- longer forcing targets to use "__main".</li>
-<li>LLVM supports assigning globals and functions to a particular section
- in the result executable using the GCC section attribute.</li>
-<li><a href="ExtendingLLVM.html">Adding intrinsics to LLVM</a> is now
- significantly easier.</li>
-<li>llvmgcc4 now fully supports C99 Variable Length Arrays, including dynamic
- stack deallocation.</li>
-
-</ul>
-</div>
-
-
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="changes">Significant Changes in LLVM 1.7</a>
+<a name="changes">Significant Changes in LLVM 1.8</a>
</div>
<div class="doc_text">
<ul>
-<li>The official LLVM URL is now <a href="http://llvm.org/">
- http://llvm.org/</a>.</li>
-<li>The LLVM intrinsics used to be overloaded based on type: for example,
- <a href="LangRef.html#int_ctpop"><tt>llvm.ctpop</tt></a> could work with any
- integer datatype. They are now separated into different intrinsics with
- suffixes to denote their argument type (e.g. <tt>llvm.ctpop.i32</tt>)). Old
- LLVM .ll and .bc files that use these intrinsics will continue to work with
- new LLVM versions (they are transparently upgraded by the parsers), but will
- cause a warning to be emitted.</li>
-<li>The <tt>llvm.readport</tt>, <tt>llvm.writeport</tt>, <tt>llvm.readio</tt>,
- and <tt>llvm.writeio</tt> intrinsics have been removed. The first two
- were ever only supported by the X86 backend, the last two were never
- correctly supported by any target, and none were accessible through the
- C front-end. Inline assembly support can now be used to
- implement these operations.</li>
-<li>The <tt>llvm-db</tt> tool had basic support for stepping through code, which
- used the JIT. This code has been removed, and DWARF emission support added
- instead. <tt>llvm-db</tt> still exists in CVS if someone wanted to write a
- <tt>ptrace</tt> backend for it.</li>
+<li>The LLVM "SparcV9" backend (deprecated in LLVM 1.7) has been removed in
+LLVM 1.8. The LLVM "Sparc" backend replaces it.</li>
+<li>The --version option now prints more useful information, including the
+ build configuration for the tool.</li>
</ul>
</div>
@@ -382,8 +297,7 @@
<div class="doc_text">
<p>
-llvm-gcc3 has many significant problems that are fixed by llvm-gcc4. See
- those blocked on the <a href="http://llvm.org/PR498">llvm-gcc4 meta bug</a>.
+llvm-gcc3 has many significant problems that are fixed by llvm-gcc4.
Two major ones include:</p>
<ul>
@@ -401,6 +315,11 @@
href="http://llvm.org/PR162">with the largest union member</a>.</li>
</ul>
+
+<p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
+does not currently support Link-Time-Optimization or C++ Exception Handling,
+which llvm-gcc3 does.</p>
+
</div>
<!-- _______________________________________________________________________ -->
@@ -638,8 +557,7 @@
<div class="doc_text">
<ul>
-<li><a href="http://llvm.org/PR736">Indirect calls crash JIT on
-Darwin/x86</a>.</li>
+<li>none yet.</li>
</ul>
</div>
@@ -718,19 +636,16 @@
</div>
-
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
+ <a name="arm-be">Known problems with the ARM back-end</a>
</div>
<div class="doc_text">
<ul>
-<li><a href="http://llvm.org/PR60">[sparcv9] SparcV9 backend miscompiles
-several programs in the LLVM test suite</a></li>
-<li>The SparcV9 backend is slated to be removed before the LLVM 1.8
- release.</li>
+<li>The ARM backend is currently in early development stages, it is not
+ready for production use.</li>
</ul>
</div>
@@ -768,7 +683,7 @@
src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
<a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
- Last modified: $Date: 2006/04/20 04:24:28 $
+ Last modified: $Date: 2006/08/08 17:27:28 $
</address>
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