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author | Chris Lattner <sabre@nondot.org> | 2005-05-15 05:44:51 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2005-05-15 05:44:51 +0000 |
commit | 8a458764d69892b824f760a3308d608d5750abf4 (patch) | |
tree | bed16c70c77ae67f9bc5216d09f6dc431fec1ce4 /docs/ReleaseNotes.html | |
parent | e5eb6f829c983dfe0da6634f5ea46a2bf16f359e (diff) | |
download | external_llvm-8a458764d69892b824f760a3308d608d5750abf4.zip external_llvm-8a458764d69892b824f760a3308d608d5750abf4.tar.gz external_llvm-8a458764d69892b824f760a3308d608d5750abf4.tar.bz2 |
Substantial edits for the release notes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22045 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/ReleaseNotes.html')
-rw-r--r-- | docs/ReleaseNotes.html | 174 |
1 files changed, 125 insertions, 49 deletions
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html index 352527e..0c11255 100644 --- a/docs/ReleaseNotes.html +++ b/docs/ReleaseNotes.html @@ -33,8 +33,8 @@ <p>This document contains the release notes for the LLVM compiler infrastructure, release 1.5. 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 +known problems and major 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/1.5/">LLVM 1.5 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> @@ -60,48 +60,124 @@ href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p> <div class="doc_text"> -<p>This is the sixth public release of the LLVM compiler infrastructure.</p> +<p>This is the sixth public release of the LLVM Compiler Infrastructure.</p> -<p> At this time, LLVM is known to correctly compile a broad range of C and -C++ programs, including the SPEC CPU95 & 2000 suite. TODO. It also includes -bug fixes for those problems found since the 1.4 release.</p> +<p> At this time, LLVM is known to correctly compile a wide range of C and C++ +programs, including the SPEC CPU95 & 2000 suite. It includes bug fixes for +those problems found since the 1.4 release and a large number of new features +and enhancements, described below.</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 1.5</a> </div> -<div class="doc_text"> -<ol> - <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415"> - Interprocedural Sparse Conditional Constant Propagation</a> pass, named - -ipsccp, which is run by default at link-time.</li> - <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data structures - use about 30% less memory.</li> - <li>LLVM includes new experimental native code generators for SparcV8, - Alpha, and IA64.</li> - <li>Support for Microsoft Visual Studio is improved, and <a - href="GettingStartedVS.html">now documented</a>.</li> - <li>Configuring LLVM to build targets selectively is now implemented, via the - <tt>--enable-targets=</tt> option. This feature is documented - <a href="GettingStarted.html#config">here</a>.</li> - <li>LLVM now supports <a href="LangRef.html#callingconv">custom and - target-specific calling conventions</a>.</li> -</ol> +<!--_________________________________________________________________________--> +<div class="doc_subsubsection">New Native Code Generators</div> +<div class="doc_text"> +<p> +This release includes new native code generators for <a +href="#alpha-be">Alpha</a>, <a href="#ia64-be">IA-64</a>, and SPARC-V8 (32-bit +SPARC). These code generators are still beta quality, but are progressing +rapidly. +</p> </div> +<!--_________________________________________________________________________--> +<div class="doc_subsubsection">New Instruction Selector Framework</div> -<!--=========================================================================--> -<div class="doc_subsubsection"> -In this release, the following missing features were implemented: -</div> +<div class="doc_text"> +<p>This release includes a <a href="CodeGenerator.html#instselect">new framework +for building instruction selectors</a>, which has long been the hardest part of +building a new LLVM target. This framework handles a lot of the mundane (but +easy to get wrong) details of writing the instruction selector, such as +generating efficient code for <a +href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting +small integer types to larger types (e.g. for RISC targets with one size of +integer registers), expanding 64-bit integer operations for 32-bit hosts, etc. +Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The +SPARC backends will be migrated when time permits. +</p> +</div> + +<!--_________________________________________________________________________--> +<div class="doc_subsubsection">New Support For Custom Calling Convetions</div> <div class="doc_text"> +<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">custom and +target-specific calling conventions</a>. Traditionally, the LLVM code +generators match the native C calling conventions for a target. This is +important for compatibility, but is not very flexible. This release allows +custom calling conventions to be established for functions, and defines three +target-independent conventions (C call, fast call, and cold call) which may be +supported by code generators. When possible, the LLVM optimizer promotes C +functions to use the "fastcc" convention, allowing the use of more efficient +calling sequences (e.g., parameters are passed in registers in the X86 target). +</p> + +<p>Targets may now also define target-specific calling conventions, allowing +LLVM to fully support calling convention altering options (e.g. GCC's +<tt>-mregparm</tt> flag) and well-defined target conventions (e.g. stdcall and +fastcall on X86).</p> +</div> + +<!--_________________________________________________________________________--> +<div class="doc_subsubsection">New Support for "Proper Tail Calls"</div> +<div class="doc_text"> +<p>The release now includes support for <a +href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as +required to implement languages like Scheme. Tail calls make use of two +features: custom calling conventions (described above), which allow the code +generator to emit code for the caller to deallocate its own stack when it +returns. The second feature is a flag on the <a href="LangRef.html#i_call">call +instruction</a>, which indicates that the callee does not access the callers +stack frame (indicating that it is acceptable to deallocate the caller stack +before invoking the callee). LLVM proper tail calls run on the system stack (as +do normal calls), supports indirect tail calls, tail calls with arbitrary +numbers of arguments, tail calls where the callee requires more argument space +than the caller, etc. The only case not supported are varargs calls, but that +could be added if desired. +</p> + +<p>In order for a front-end to get guaranteed tail call, it must mark functions +as "fastcc", mark calls with the 'tail' marker, and follow the call with a +return of the called value (or void). The optimizer and code generator attempt +to handle more general cases, but the simple case will always work if the code +generator supports tail calls. Here is a simple example:</p> + +<p><pre> +fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i> + %Y = tail call fastcc int %FP(double 0.0, int %X) ;<i> tail, fastcc</i> + ret int %Y +} +</pre></p> + +<p>In LLVM 1.5, the X86 code generator is the only target that has been enhanced +to support proper tail calls (other targets will be enhanced in future). +Further, because this support was added very close to the release, it is +disabled by default. Pass <tt>-enable-x86-fastcc</tt> to llc to enable it. X86 +support will be enabled by default in the next LLVM release.</p> +</div> + +<!--_________________________________________________________________________--> +<div class="doc_subsubsection">Other New Features</div> + +<div class="doc_text"> <ol> + <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415"> + Interprocedural Sparse Conditional Constant Propagation</a> pass, named + -ipsccp, which is run by default at link-time.</li> + <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data + structures use about 30% less memory.</li> + <li>Support for Microsoft Visual Studio is improved, and <a + href="GettingStartedVS.html">now documented</a>.</li> + <li><a href="GettingStarted.html#config">Configuring LLVM to build a subset + of the available targets</a> is now implemented, via the + <tt>--enable-targets=</tt> option.</li> <li>LLVM can now create native shared libraries with '<tt>llvm-gcc ... -shared -Wl,-native</tt>' (or with <tt>-Wl,-native-cbe</tt>).</li> <li>LLVM now supports a new "<a href="LangRef.html#i_prefetch">llvm.prefetch @@ -110,40 +186,38 @@ In this release, the following missing features were implemented: counting</a> and llvm-gcc now implements the GCC <tt>__builtin_popcount</tt>, <tt>__builtin_ctz</tt>, and <tt>__builtin_clz</tt> builtins.</li> + <li>LLVM now builds on HP-UX with the HP aCC Compiler.</li> + <li>The LLVM X86 backend can now emit Cygwin-compatible .s files.</li> + <li>LLVM now includes workarounds in the code generator generator which + reduces the likelyhood of <a href="http://llvm.cs.uiuc.edu/PR448">GCC + hitting swap during optimized builds</a>.</li> </ol> - </div> <!--=========================================================================--> -<div class="doc_subsubsection"> -<a name="qualityofimp">In this release, the following Quality of Implementation -issues were fixed:</a> +<div class="doc_subsection"> +<a name="codequality">Code Quality Improvements in LLVM 1.5</a> </div> <div class="doc_text"> - <ol> - <li><a href="http://llvm.cs.uiuc.edu/PR448">Building LLVM in optimized mode - should no longer cause GCC to hit swap in the PowerPC backend.</a></li> -</ol> -</div> +<li>The -globalopt pass now promotes non-address-taken static globals that are +only accessed in main to SSA registers.</li> -<!--=========================================================================--> -<div class="doc_subsubsection"> -<a name="codequality">This release includes the following Code Quality -improvements:</a> -</div> +<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i += 0; &A[i] != &A[100]; ++i) ...</tt>") are optimized better than before, +which primarily helps iterator-intensive C++ codes.</li> -<div class="doc_text"> -<ol> - <li>Transition code for 1.0 style varargs was removed. </li> +<li>The code generator now uses information about takes advantage of commutative +two-address instructions when performing register allocation.</li> + + </ol> </div> <!--=========================================================================--> -<div class="doc_subsubsection"> -<a name="bugfix">In this release, the following bugs in the previous release -were fixed:</a> +<div class="doc_subsection"> +<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a> </div> <div class="doc_text"> @@ -155,6 +229,8 @@ were fixed:</a> are partially overwritten by smaller stores</a></li> <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of setcc or setcc in one case</a></li> + <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file + parser. LLVM 1.0 bytecode files are still supported. </li> </ol> <p>Code Generator Bugs:</p> |