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| author | Chris Lattner <sabre@nondot.org> | 2009-02-25 04:41:31 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2009-02-25 04:41:31 +0000 |
| commit | 38ab04cb442c30806af65b4013260c441ffc6576 (patch) | |
| tree | 8ab7eaa52fedb114525a03eaffae344c931f7181 | |
| parent | 8f1579aedca03f089e239552ba7f1398e657c6f5 (diff) | |
| download | external_llvm-38ab04cb442c30806af65b4013260c441ffc6576.zip external_llvm-38ab04cb442c30806af65b4013260c441ffc6576.tar.gz external_llvm-38ab04cb442c30806af65b4013260c441ffc6576.tar.bz2 | |
rip out llvm 2.4 details to make room for 2.5
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65429 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | docs/ReleaseNotes.html | 261 |
1 files changed, 19 insertions, 242 deletions
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html index b74463b..d7f1c47 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 2.4 Release Notes</title> + <title>LLVM 2.5 Release Notes</title> </head> <body> -<div class="doc_title">LLVM 2.4 Release Notes</div> +<div class="doc_title">LLVM 2.5 Release Notes</div> <ol> <li><a href="#intro">Introduction</a></li> @@ -33,7 +33,7 @@ <div class="doc_text"> <p>This document contains the release notes for the LLVM Compiler -Infrastructure, release 2.4. Here we describe the status of LLVM, including +Infrastructure, release 2.5. Here we describe the status of LLVM, including major improvements from the previous release and significant known problems. All LLVM releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p> @@ -51,7 +51,7 @@ current one. To see the release notes for a specific release, please see the </div> -<!-- Unfinished features in 2.4: +<!-- Unfinished features in 2.5: Machine LICM Machine Sinking LegalizeDAGTypes @@ -72,7 +72,7 @@ current one. To see the release notes for a specific release, please see the <div class="doc_text"> <p> -The LLVM 2.4 distribution currently consists of code from the core LLVM +The LLVM 2.5 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 @@ -170,21 +170,13 @@ The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of a JVM and a CLI Virtual Machines (Microsoft .NET is an implementation of the CLI) using the Just-In-Time compiler of LLVM.</p> -<p>Following LLVM 2.4, VMKit has its first release 0.24 that you can find on its +<p>Following LLVM 2.5, VMKit has its first release 0.24 that you can find on its <a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes bug fixes, cleanup and new features. The major changes are:</p> <ul> -<li> Support for generics in the .Net virtual machine.</li> -<li> Initial support for the Mono class libraries. </li> -<li> Support for MacOSX/x86, following LLVM's support for exceptions in -JIT on MacOSX/x86. </li> -<li> A new vmkit driver: a program to run java or .net applications. The driver -supports llvm command line arguments including the new "-fast" option. </li> -<li> A new memory allocation scheme in the JVM that makes unloading a -class loader very fast. </li> -<li> VMKit now follows the LLVM Makefile machinery. </li> +<li>?</li> </ul> </div> @@ -211,29 +203,10 @@ in this section. <div class="doc_text"> -<p>LLVM 2.4 includes several major new capabilities:</p> +<p>LLVM 2.5 includes several major new capabilities:</p> <ul> -<li><p>The most visible end-user change in LLVM 2.4 is that it includes many -optimizations and changes to make -O0 compile times much faster. You should see -improvements in speed on the order of 30% (or more) than in LLVM 2.3. There are -many pieces to this change described in more detail below. The speedups and new -components can also be used for JIT compilers that want fast -compilation.</p></li> - -<li><p>The biggest change to the LLVM IR is that Multiple Return Values (which -were introduced in LLVM 2.3) have been generalized to full support for "First -Class Aggregate" values in LLVM 2.4. This means that LLVM IR supports using -structs and arrays as values in a function. This capability is mostly useful -for front-end authors, who prefer to treat things like complex numbers, simple -tuples, dope vectors, etc., as Value*'s instead of as a tuple of Value*'s or as -memory values. Bitcode files from LLVM 2.3 will automatically migrate to the -general representation.</p></li> - -<li><p>LLVM 2.4 also includes an initial port for the PIC16 microprocessor. This -target only has support for 8 bit registers, and a number of other crazy -constraints. While the port is still in early development stages, it shows some -interesting things you can do with LLVM.</p></li> +<li><p>?</p></li> </ul> @@ -252,29 +225,7 @@ front-ends and driver with the LLVM optimizer and code generator. It currently includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p> <ul> -<li>LLVM 2.4 supports the full set of atomic <tt>__sync_*</tt> builtins. LLVM -2.3 only supported those used by OpenMP, but 2.4 supports them all. Note that -while llvm-gcc supports all of these builtins, not all targets do. X86 support -them all in both 32-bit and 64-bit mode and PowerPC supports them all except for -the 64-bit operations when in 32-bit mode.</li> - -<li>llvm-gcc now supports an <tt>-flimited-precision</tt> option, which tells -the compiler that it is okay to use low-precision approximations of certain libm -functions (like <tt>exp</tt>, <tt>log</tt>, etc). This allows you to get high -performance if you only need (say) 12-bits of precision.</li> - -<li>llvm-gcc now supports a C language extension known as "<a -href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks</a>". -This feature is similar to nested functions and closures, but does not -require stack trampolines (with most ABIs), and supports returning closures -from functions that define them. Note that actually <em>using</em> Blocks -requires a small runtime that is not included with llvm-gcc.</li> - -<li>llvm-gcc now supports a new <tt>-flto</tt> option. On systems that support -transparent Link Time Optimization (currently Darwin systems with Xcode 3.1 and -later) this allows the use of LTO with other optimization levels like -Os. -Previously, LTO could only be used with -O4, which implied optimizations in --O3 that can increase code size.</li> +<li>?</li> </ul> </div> @@ -289,43 +240,7 @@ Previously, LTO could only be used with -O4, which implied optimizations in <p>New features include:</p> <ul> -<li>A major change to the <tt>Use</tt> class landed, which shrank it by 25%. Since -this is a pervasive part of the LLVM, it ended up reducing the memory use of -LLVM IR in general by 15% for most programs.</li> - -<li>Values with no names are now pretty printed by <tt>llvm-dis</tt> more -nicely. They now print as "<tt>%3 = add i32 %A, 4</tt>" instead of -"<tt>add i32 %A, 4 ; <i32>:3</tt>", which makes it much easier to read. -</li> - -<li>LLVM 2.4 includes some changes for better vector support. First, the shift -operations (<tt>shl</tt>, <tt>ashr</tt>, and <tt>lshr</tt>) now all support -vectors and do an element-by-element shift (shifts of the whole vector can be -accomplished by bitcasting the vector to <tt><1 x i128></tt>, for example). Second, -there is initial support in development for vector comparisons with the -<tt><a href="LangRef.html#i_fcmp">fcmp</a>/<a href="LangRef.html#i_icmp">icmp</a></tt> -instructions. These instructions compare two vectors and return a vector of -<tt>i1</tt>'s for each result. Note that there is very little codegen support -available for any of these IR features though.</li> - -<li>A new <tt>DebugInfoBuilder</tt> class is available, which makes it much -easier for front-ends to create debug info descriptors, similar to the way that -<tt>IRBuilder</tt> makes it easier to create LLVM IR.</li> - -<li>The <tt>IRBuilder</tt> class is now parameterized by a class responsible -for constant folding. The default <tt>ConstantFolder</tt> class does target independent -constant folding. The <tt>NoFolder</tt> class does no constant folding at all, which is -useful when learning how LLVM works. The <tt>TargetFolder</tt> class folds the most, -doing target dependent constant folding.</li> - -<li>LLVM now supports "function attributes", which allow us to separate return -value attributes from function attributes. LLVM now supports attributes on a -function itself, a return value, and its parameters. New supported function -attributes include <tt>noinline/alwaysinline</tt> and the <tt>opt-size</tt> flag, -which says the function should be optimized for code size.</li> - -<li>LLVM IR now directly represents "common" linkage, instead of - representing it as a form of weak linkage.</li> +<li>?</li> </ul> @@ -343,39 +258,7 @@ release includes a few major enhancements and additions to the optimizers:</p> <ul> -<li>The Global Value Numbering (GVN) pass now does local Partial Redundancy -Elimination (PRE) to eliminate some partially redundant expressions in cases -where doing so won't grow code size.</li> - -<li>LLVM 2.4 includes a new loop deletion pass (which removes output-free -provably-finite loops) and a rewritten Aggressive Dead Code Elimination (ADCE) -pass that no longer uses control dependence information. These changes speed up -the optimizer and also prevent it from deleting output-free infinite -loops.</li> - -<li>The new AddReadAttrs pass works out which functions are read-only or -read-none (these correspond to 'pure' and 'const' in GCC) and marks them -with the appropriate attribute.</li> - -<li>LLVM 2.4 now includes a new SparsePropagation framework, which makes it -trivial to build lattice-based dataflow solvers that operate over LLVM IR. Using -this interface means that you just define objects to represent your lattice -values and the transfer functions that operate on them. It handles the -mechanics of worklist processing, liveness tracking, handling PHI nodes, -etc.</li> - -<li>The Loop Strength Reduction and induction variable optimization passes have -several improvements to avoid inserting MAX expressions, to optimize simple -floating point induction variables and to analyze trip counts of more -loops.</li> - -<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were -pulled out of the Instruction Combining pass and put into a new -<tt>ValueTracking.h</tt> header, where they can be reused by other passes.</li> - -<li>The tail duplication pass has been removed from the standard optimizer -sequence used by llvm-gcc. This pass still exists, but the benefits it once -provided are now achieved by other passes.</li> +<li>?</li> </ul> @@ -393,41 +276,7 @@ which allows us to implement more aggressive algorithms and make it run faster:</p> <ul> -<li>The target-independent code generator supports (and the X86 backend - currently implements) a new interface for "fast" instruction selection. This - interface is optimized to produce code as quickly as possible, sacrificing - code quality to do it. This is used by default at -O0 or when using - "llc -fast" on X86. It is straight-forward to add support for - other targets if faster -O0 compilation is desired.</li> - -<li>In addition to the new 'fast' instruction selection path, many existing - pieces of the code generator have been optimized in significant ways. - SelectionDAG's are now pool allocated and use better algorithms in many - places, the ".s" file printers now use <tt>raw_ostream</tt> to emit text much faster, - etc. The end result of these improvements is that the compiler also takes - substantially less time to generate code that is just as good (and often - better) than before.</li> - -<li>Each target has been split to separate the ".s" file printing logic from the - rest of the target. This enables JIT compilers that don't link in the - (somewhat large) code and data tables used for printing a ".s" file.</li> - -<li>The code generator now includes a "stack slot coloring" pass, which packs - together individual spilled values into common stack slots. This reduces - the size of stack frames with many spills, which tends to increase L1 cache - effectiveness.</li> - -<li>Various pieces of the register allocator (e.g. the coalescer and two-address - operation elimination pass) now know how to rematerialize trivial operations - to avoid copies and include several other optimizations.</li> - -<li>The <a href="CodeGenerator.html#selectiondag_process">graphs</a> produced by - the <tt>llc -view-*-dags</tt> options are now significantly prettier and - easier to read.</li> - -<li>LLVM 2.4 includes a new register allocator based on Partitioned Boolean - Quadratic Programming (PBQP). This register allocator is still in - development, but is very simple and clean.</li> +<li>?</li> </ul> @@ -444,17 +293,7 @@ faster:</p> </p> <ul> -<li>Exception handling is supported by default on Linux/x86-64.</li> -<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li> -<li><tt>@llvm.frameaddress</tt> now supports getting the frame address of stack frames - > 0 on x86/x86-64.</li> -<li>MIPS has improved a lot since last release, the most important changes - are: Little endian support, floating point support, allegrex core and - intrinsics support. O32 ABI is improved but isn't complete. The EABI - was implemented and is fully supported. We also have support for small - sections and gp_rel relocation for its access, a threshold in bytes can be - specified through command line.</li> -<li>The PowerPC backend now supports trampolines.</li> +<li>?</li> </ul> </div> @@ -470,21 +309,7 @@ faster:</p> </p> <ul> -<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin - support. It is now easier to experiment with <tt>llvmc2</tt> and - build your own tools based on it.</li> - -<li>LLVM 2.4 includes a number of new generic algorithms and data structures, - including a scoped hash table, 'immutable' data structures, a simple - free-list manager, and a <tt>raw_ostream</tt> class. - The <tt>raw_ostream</tt> class and - <tt>format</tt> allow for efficient file output, and various pieces of LLVM - have switched over to use it. The eventual goal is to eliminate - use of <tt>std::ostream</tt> in favor of it.</li> - -<li>LLVM 2.4 includes an optional build system based on CMake. It - still is in its early stages but can be useful for Visual C++ - users who can not use the Visual Studio IDE.</li> +<li>?</li> </ul> @@ -498,19 +323,12 @@ faster:</p> <div class="doc_text"> <p>If you're already an LLVM user or developer with out-of-tree changes based -on LLVM 2.3, this section lists some "gotchas" that you may run into upgrading +on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading from the previous release.</p> <ul> -<li>The LLVM IR generated by llvm-gcc no longer names all instructions. This - makes it run faster, but may be more confusing to some people. If you - prefer to have names, the '<tt>opt -instnamer</tt>' pass will add names to - all instructions.</li> - -<li>The LoadVN and GCSE passes have been removed from the tree. They are - obsolete and have been replaced with the GVN and MemoryDependence passes. - </li> +<li>?</li> </ul> @@ -518,51 +336,10 @@ from the previous release.</p> API changes are:</p> <ul> - -<li>Now, function attributes and return value attributes are managed -separately. Interface exported by <tt>ParameterAttributes.h</tt> header is now -exported by <tt>Attributes.h</tt> header. The new attributes interface changes are: -<ul> -<li><tt>getParamAttrs</tt> method is now replaced by -<tt>getParamAttributes</tt>, <tt>getRetAttributes</tt> and -<tt>getFnAttributes</tt> methods.</li> -<li> Return value attributes are stored at index 0. Function attributes are -stored at index ~0U. Parameter attributes are stored at index that matches -parameter number.</li> -<li> <tt>ParamAttr</tt> namespace is now renamed as <tt>Attribute</tt>.</li> -<li> The name of the class that manages reference count of opaque -attributes is changed from <tt>PAListPtr</tt> to <tt>AttrListPtr</tt>.</li> -<li> <tt>ParamAttrsWithIndex</tt> is now renamed as <tt>AttributeWithIndex</tt>. -</li> +<li>?</li> </ul> -</li> -<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and -<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be -converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via -"<tt>llvm/Analysis/ValueTracking.h</tt>".</li> - -<li>The APIs to create various instructions have changed from lower case - "create" methods to upper case "Create" methods (e.g. - <tt>BinaryOperator::create</tt>). LLVM 2.4 includes both cases, but the - lower case ones are removed in mainline (2.5 and later), please migrate.</li> - -<li>Various header files like "<tt>llvm/ADT/iterator</tt>" were given a ".h" suffix. - Change your code to #include "<tt>llvm/ADT/iterator.h</tt>" instead.</li> - -<li>The <tt>getresult</tt> instruction has been removed and replaced with the - <tt>extractvalue</tt> instruction. This is part of support for first class - aggregates.</li> - -<li>In the code generator, many <tt>MachineOperand</tt> predicates were renamed to be - shorter (e.g. <tt>isFrameIndex()</tt> -> <tt>isFI()</tt>), - <tt>SDOperand</tt> was renamed to <tt>SDValue</tt> (and the "<tt>Val</tt>" - member was changed to be the <tt>getNode()</tt> accessor), and the - <tt>MVT::ValueType</tt> enum has been replaced with an "<tt>MVT</tt>" - struct. The <tt>getSignExtended</tt> and <tt>getValue</tt> methods in the - ConstantSDNode class were renamed to <tt>getSExtValue</tt> and - <tt>getZExtValue</tt> respectively, to be more consistent with - the <tt>ConstantInt</tt> class.</li> +<li>?</li> </ul> </div> |