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| author | John Criswell <criswell@uiuc.edu> | 2005-05-18 20:28:46 +0000 |
|---|---|---|
| committer | John Criswell <criswell@uiuc.edu> | 2005-05-18 20:28:46 +0000 |
| commit | 98391cedd578b3dc4a63d8f3a1d118eeea653386 (patch) | |
| tree | e939113bfdc2b55556a8661b6f72fea8171b624a /docs/ReleaseNotes.html | |
| parent | 0e9dfcb10cfdab9a5897cc376f0c9ad1a8dec0bc (diff) | |
| download | external_llvm-98391cedd578b3dc4a63d8f3a1d118eeea653386.zip external_llvm-98391cedd578b3dc4a63d8f3a1d118eeea653386.tar.gz external_llvm-98391cedd578b3dc4a63d8f3a1d118eeea653386.tar.bz2 | |
New Release Notes for LLVM 1.6.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22124 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/ReleaseNotes.html')
| -rw-r--r-- | docs/ReleaseNotes.html | 276 |
1 files changed, 11 insertions, 265 deletions
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html index 1c2db4e..1200008 100644 --- a/docs/ReleaseNotes.html +++ b/docs/ReleaseNotes.html @@ -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 1.5 Release Notes</title> + <title>LLVM 1.6 Release Notes</title> </head> <body> -<div class="doc_title">LLVM 1.5 Release Notes</div> +<div class="doc_title">LLVM 1.6 Release Notes</div> <ol> <li><a href="#intro">Introduction</a></li> @@ -32,10 +32,10 @@ <div class="doc_text"> <p>This document contains the release notes for the LLVM compiler -infrastructure, release 1.5. Here we describe the status of LLVM, including any +infrastructure, release 1.6. 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 -href="http://llvm.cs.uiuc.edu/releases/1.5/">LLVM 1.5 web site</a>. If you are +href="http://llvm.cs.uiuc.edu/releases/1.6/">LLVM 1.6 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> @@ -60,286 +60,32 @@ 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 seventh public release of the LLVM Compiler Infrastructure.</p> -<p>LLVM 1.5 is known to correctly compile a wide range of C and C++ programs, -includes bug fixes for those problems found since the 1.4 release, and includes +<p>LLVM 1.6 is known to correctly compile a wide range of C and C++ programs, +includes bug fixes for those problems found since the 1.5 release, and includes a large number of new features and enhancements, described below.</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="newfeatures">New Features in LLVM 1.5</a> -</div> - -<!--_________________________________________________________________________--> -<div class="doc_subsubsection"><a name="newcg">New Native Code -Generators</a></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 <a -href="#sparcv8">SPARC-V8</a> (32-bit SPARC). These code generators are still -beta quality, but are progressing rapidly. The Alpha backend is implemented -with an eye towards being compatible with the widely used SimpleScalar -simulator. -</p> -</div> - -<!--_________________________________________________________________________--> -<div class="doc_subsubsection"><a name="selectiondag">New Instruction -Selector Framework</a></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 targets, 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"><a name="customccs">New Support for Per-Function -Calling Conventions</a></div> - -<div class="doc_text"> -<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">per-function -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 (<a -href="LangRef.html#callingconv">C call, fast call, and cold call</a>) 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"><a name="tailcalls">New Support for -Proper Tail Calls</a></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 use a convention where the caller deallocates its stack before 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 caller's -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>To ensure a call is interpreted as a tail call, a front-end 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 an example:</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>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 (this -will be enabled by default in the next release). The example above compiles to: -</p> - -<pre> - bar: - sub ESP, 8 # Callee uses more space than the caller - mov ECX, DWORD PTR [ESP + 8] # Get the old return address - mov DWORD PTR [ESP + 4], 0 # First half of 0.0 - mov DWORD PTR [ESP + 8], 0 # Second half of 0.0 - mov DWORD PTR [ESP], ECX # Put the return address where it belongs - jmp EDX # Tail call "FP" -</pre> - -<p> -With fastcc on X86, the first two integer arguments are passed in EAX/EDX, the -callee pops its arguments off the stack, and the argument area is always a -multiple of 8 bytes in size. -</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>. Most LLVM tools build - natively with Visual C++ now.</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 - </a>" intrinsic, and llvm-gcc now supports __builtin_prefetch. - <li>LLVM now supports intrinsics for <a href="LangRef.html#int_count">bit - 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 mostly 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> - <li>The <a href="http://llvm.cs.uiuc.edu/ProjectsWithLLVM/#llvmtv">LLVM - Transformation Visualizer</a> (llvm-tv) project has been updated to - work with LLVM 1.5.</li> - <li>Nightly tester output is now archived on the <a - href="http://mail.cs.uiuc.edu/pipermail/llvm-testresults/"> - llvm-testresults</a> mailing list.</li> - -</ol> +<a name="newfeatures">New Features in LLVM 1.6</a> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="codequality">Code Quality Improvements in LLVM 1.5</a> +<a name="codequality">Code Quality Improvements in LLVM 1.6</a> </div> -<div class="doc_text"> -<ol> -<li>The new -simplify-libcalls pass improves code generated for well-known -library calls. The pass optimizes calls to many of the string, memory, and -standard I/O functions (e.g. replace the calls with simpler/faster calls) when -possible, given information known statically about the arguments to the call. -</li> - -<li>The -globalopt pass now promotes non-address-taken static globals that are -only accessed in main to SSA registers.</li> - -<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i -= 0; &A[i] != &A[n]; ++i) ...</tt>") are optimized better than before, -which primarily helps iterator-intensive C++ code.</li> - -<li>The optimizer now eliminates simple cases where redundant conditions exist - between neighboring blocks.</li> - -<li>The reassociation pass (which turns (1+X+3) into (X+1+3) among other -things), is more aggressive and intelligent.</li> - -<li>The -prune-eh pass now detects no-return functions in addition to the - no-unwind functions it did before.</li> - -<li>The -globalsmodref alias analysis generates more precise results in some - cases.</li> -</ol> -</div> - - <!--=========================================================================--> <div class="doc_subsection"> -<a name="codequality">Code Generator Improvements in LLVM 1.5</a> -</div> - -<div class="doc_text"> -<ol> -<li>The code generator now can provide and use information about commutative - two-address instructions when performing register allocation.</li> - -<li>The code generator now tracks function live-in registers explicitly, - instead of requiring the target to generate 'implicit defs' at the - entry to a function.</li> - -<li>The code generator can lower integer division by a constant to - multiplication by a magic constant and multiplication by a constant into - shift/add sequences.</li> - -<li>The code generator compiles fabs/fneg/sin/cos/sqrt to assembly instructions - when possible.</li> - -<li>The PowerPC backend generates better code in many cases, making use of - FMA instructions and the recording ("dot") forms of various PowerPC - instructions.</li> -</ol> +<a name="codequality">Code Generator Improvements in LLVM 1.6</a> </div> - <!--=========================================================================--> <div class="doc_subsection"> -<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a> -</div> - -<div class="doc_text"> - - -<p>Bugs fixed in the LLVM Core:</p> -<ol> - <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that - 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> -<ol> - <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant - expressions (and/or/xor) not implemented</a>.</li> - <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not - respect 'volatile'</a>.</li> - <li>The JIT sometimes miscompiled globals and constant pool entries for - 64-bit integer constants on 32-bit hosts.</li> - <li>The C backend should no longer produce code that crashes ICC 8.1.</li> -</ol> - -<p>Bugs in the C/C++ front-end:</p> -<ol> - <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly - rejects some constant initializers involving the addresses of array - elements</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling - anonymous union</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic - initialization where static init will do</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset - miscalculated for some structure fields following bit fields</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes - incorrect for short circuit logical operations</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling - bitfield <-> aggregate assignment</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling - virtual function thunk with an unnamed argument</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain - C99 complex number routines</a></li> - <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement - new on an array type</a></li> -</ol> - +<a name="bugfix">Significant Bugs Fixed in LLVM 1.6</a> </div> <!-- *********************************************************************** --> |