[llvm-commits] [llvm] r83716 - /llvm/trunk/docs/ReleaseNotes-2.6.html
Chris Lattner
sabre at nondot.org
Sat Oct 10 11:33:13 PDT 2009
Author: lattner
Date: Sat Oct 10 13:33:13 2009
New Revision: 83716
URL: http://llvm.org/viewvc/llvm-project?rev=83716&view=rev
Log:
checkpoint.
Modified:
llvm/trunk/docs/ReleaseNotes-2.6.html
Modified: llvm/trunk/docs/ReleaseNotes-2.6.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/ReleaseNotes-2.6.html?rev=83716&r1=83715&r2=83716&view=diff
==============================================================================
--- llvm/trunk/docs/ReleaseNotes-2.6.html (original)
+++ llvm/trunk/docs/ReleaseNotes-2.6.html Sat Oct 10 13:33:13 2009
@@ -92,11 +92,10 @@
<div class="doc_text">
<p>
The LLVM 2.6 distribution currently consists of code from the core LLVM
-repository —which roughly includes the LLVM optimizers, code generators
-and supporting tools — and the llvm-gcc repository. In addition to this
-code, the LLVM Project includes other sub-projects that are in development. The
-two which are the most actively developed are the <a href="#clang">Clang
-Project</a> and the <a href="#vmkit">VMKit Project</a>.
+repository (which roughly includes the LLVM optimizers, code generators
+and supporting tools), the Clang repository and the llvm-gcc 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>
</div>
@@ -112,8 +111,12 @@
<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
a set of new 'LLVM native' front-end technologies for the C family of languages.
LLVM 2.6 is the first release to officially include Clang, and it provides a
-production quality C and Objective-C compiler. If you are interested in fast
-compiles and good diagnostics, we encourage you to try it out.</p>
+production quality C and Objective-C compiler. If you are interested in <a
+href="http://clang.llvm.org/performance.html">fast compiles</a> and
+<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
+encourage you to try it out. Clang currently compiles typical Objective-C code
+3x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
+(which is when the most pressure is on the frontend).</p>
<p>In addition to supporting these languages, C++ support is also <a
href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
@@ -127,7 +130,7 @@
<ul>
<li>C and Objective-C support are now considered production quality.</li>
-<li>AuroraUX / FreeBSD & OpenBSD Toolchain support.</li>
+<li>AuroraUX, FreeBSD, and OpenBSD are now supported.</li>
<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
<li>Many many bugs are fixed and many features have been added.</li>
</ul>
@@ -201,8 +204,9 @@
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 compiling into a runtime call to the "__fixunsdfdi"
-function. The compiler-rt library provides optimized implementations of this and
-other low-level routines.</p>
+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>
All of the code in the compiler-rt project is available under the standard LLVM
@@ -282,6 +286,14 @@
</div>
<!-- *********************************************************************** -->
+<div class="doc_text">
+
+<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 2.6.</p>
+</div>
+
+
<!--=========================================================================-->
<div class="doc_subsection">
<a name="Rubinius">Rubinius</a>
@@ -440,16 +452,14 @@
enables support for <a href="LinkTimeOptimization.html">transparent
link-time optimization</a> on ELF targets when used with the Gold binutils
linker.</li>
-<li>LLVM now supports doing optimization and code generation on multiple threads
- by allowing multiple "LLVMContext" objects to exist. Please see the <a
- href="ProgrammersManual.html#threading">threading entry in the Programmer's
- Manual</a> for more information.</li>
+<li>LLVM now supports doing optimization and code generation on multiple
+ threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
+ Programmer's Manual</a> for more information.</li>
<li>LLVM now has experimental support for <a
href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
metadata</a> in LLVM IR, though the implementation is not guaranteed to be
final and the .bc file format may change in future releases. Debug info
- does not yet use this format in LLVM 2.6.</p>
-
+ does not yet use this format in LLVM 2.6.</li>
</ul>
</div>
@@ -460,18 +470,54 @@
</div>
<div class="doc_text">
-<p>LLVM IR has several new features that are used by our existing front-ends and
-can be useful if you are writing a front-end for LLVM:</p>
+<p>LLVM IR has several new features for better support of new targets and that
+expose new optimization opportunities:</p>
<ul>
-<li>Getelementpr instruction now allows any integer type for array/pointer indexes.</li>
-<li>Inbounds for GEP</li>
-<li>NSW/NUW/exact div</li>
-<li>LSR promotes int induction variables to 64-bit on 64-bit targets, major perf boost for numerical code.</li>
-<li>LSR now analyzes pointer expressions (e.g. getelementptrs), not just integers.</li>
-<li>new linkage types linkonce_odr, weak_odr, linker_private, and available_externally.</li>
-<li>New fadd, fsub, fmul instructions and classes. </li>
-<li>Target intrinsics can now return multiple results.</li>
+<li>The <a href="LangRef.html#i_add">add</a>, <a
+ href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
+ instructions have been split into integer and floating point version (like
+ divide and remainder), introducing new <a
+ href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
+ and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
+<li>The <a href="LangRef.html#i_add">add</a>, <a
+ href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
+ instructions now support optional "nsw" and "nuw" bits which indicate that
+ the operation is guaranteed to not overflow (in the signed or
+ unsigned case, respectively). This gives the optimizer more information and
+ can be used for things C signed integer values, which are undefined on
+ overflow.</li>
+<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
+ optional "exact" flag which indicates that the result of the division is
+ guaranteed to have a remainder of zero. This is useful to optimize pointer
+ subtraction in C.</li>
+<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
+ supports arbitrary integer index values for array/pointer indices. This
+ allows for better better code generation on 16-bit targets like PIC16.</li>
+<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
+ supports an "inbounds" optimization hint that tells the optimizer that the
+ pointer is guaranteed to be within its allocated object.</li>
+<li>LLVM now support a series of new linkage types for global values which allow
+ for better optimization and new capabilities:
+ <ul>
+ <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
+ <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
+ semantics as the non-"odr" linkage types. The difference is that these
+ linkage types indicate that all definitions of the specified function
+ are guaranteed to have the same semantics. This allows inlining
+ templates functions in C++ but not inlining weak functions in C,
+ which previously both got the same linkage type.</li>
+ <li><a href="LangRef.html#linkage_available_externally">available_externally
+ </a> is a new linkage type that gives the optimizer visibility into the
+ definition of a function (allowing inlining and side effect analysis)
+ but that does not cause code to be generated. This allows better
+ optimization of "GNU inline" functions, extern templates, etc.</li>
+ <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
+ new linkage type (which is only useful on Mac OS X) that is used for
+ some metadata generation and other obscure things.</li>
+ </ul></li>
+<li>Finally, target-specific intrinsics can now return multiple values, which
+ is useful for modeling target operations with multiple results.</li>
</ul>
</div>
@@ -492,6 +538,8 @@
<li>Inliner reuse stack space when inlining arrays?</li>
<li>Enabled GVN Load PRE.</li>
<li>New Static Single Information (SSI) construction pass (not used by anything yet, experimental).</li>
+<li>LSR promotes int induction variables to 64-bit on 64-bit targets, major perf boost for numerical code.</li>
+<li>LSR now analyzes pointer expressions (e.g. getelementptrs), not just integers.</li>
</li>
</ul>
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