From 074eeaae30f12dc2077641e1d12ae2011f0e4f42 Mon Sep 17 00:00:00 2001 From: NAKAMURA Takumi Date: Thu, 21 Apr 2011 01:52:00 +0000 Subject: [PATCH] docs/llvm.css: Introduce cascading style
and

continued on . For now, it is applied in AliasAnalysis.html and ReleaseNotes.html.

Section Example

Section preamble.

Subsection Example

Subsection body

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129901 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/AliasAnalysis.html | 129 ++++++++++++++++++++-------------------- docs/ReleaseNotes.html | 100 +++++++++++++++---------------- docs/llvm.css | 4 ++ 3 files changed, 119 insertions(+), 114 deletions(-) diff --git a/docs/AliasAnalysis.html b/docs/AliasAnalysis.html index bed3aceeb5c..306a3f4393c 100644 --- a/docs/AliasAnalysis.html +++ b/docs/AliasAnalysis.html @@ -64,7 +64,7 @@ -
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Alias Analysis (aka Pointer Analysis) is a class of techniques which attempt to determine whether or not two pointers ever can point to the same object in @@ -101,7 +101,7 @@ know.

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The AliasAnalysis @@ -122,14 +122,12 @@ multiple values, values which are not constants are all defined within the same function.

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Representation of Pointers

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Most importantly, the AliasAnalysis class provides several methods which are used to query whether or not two memory objects alias, whether @@ -185,7 +183,7 @@ that the accesses alias.

The alias method -
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The alias method is the primary interface used to determine whether or not two memory objects alias each other. It takes two memory objects as input and returns MustAlias, PartialAlias, MayAlias, or NoAlias as @@ -194,14 +192,13 @@ appropriate.

Like all AliasAnalysis interfaces, the alias method requires that either the two pointer values be defined within the same function, or at least one of the values is a constant.

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Must, May, and No Alias Responses

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The NoAlias response may be used when there is never an immediate dependence between any memory reference based on one pointer and any memory reference based the other. The most obvious example is when the two @@ -227,12 +224,14 @@ implies that the pointers compare equal.

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The getModRefInfo methods

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The getModRefInfo methods return information about whether the execution of an instruction can read or modify a memory location. Mod/Ref @@ -254,21 +253,19 @@ memory written to by CS2. Note that this relation is not commutative.

Other useful AliasAnalysis methods -
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Several other tidbits of information are often collected by various alias analysis implementations and can be put to good use by various clients.

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The pointsToConstantMemory method

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The pointsToConstantMemory method returns true if and only if the analysis can prove that the pointer only points to unchanging memory locations @@ -284,7 +281,7 @@ memory location to be modified.

onlyReadsMemory methods -
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These methods are used to provide very simple mod/ref information for function calls. The doesNotAccessMemory method returns true for a @@ -307,13 +304,17 @@ functions that satisfy the doesNotAccessMemory method also satisfies

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Writing a new AliasAnalysis Implementation

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Writing a new alias analysis implementation for LLVM is quite straight-forward. There are already several implementations that you can use @@ -321,14 +322,12 @@ for examples, and the following information should help fill in any details. For a examples, take a look at the various alias analysis implementations included with LLVM.

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Different Pass styles

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The first step to determining what type of LLVM pass you need to use for your Alias @@ -356,7 +355,7 @@ solve:

Required initialization calls -
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Your subclass of AliasAnalysis is required to invoke two methods on the AliasAnalysis base class: getAnalysisUsage and @@ -397,7 +396,7 @@ bool run(Module &M) { Interfaces which may be specified -

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All of the AliasAnalysis @@ -416,7 +415,7 @@ implementing, you just override the interfaces you can improve.

AliasAnalysis chaining behavior -
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With only two special exceptions (the basicaa and no-aa @@ -455,7 +454,7 @@ updated.

Updating analysis results for transformations -
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Alias analysis information is initially computed for a static snapshot of the program, but clients will use this information to make transformations to the @@ -471,12 +470,11 @@ their internal data structures are kept up-to-date as the program changes (for example, when an instruction is deleted), and clients of alias analysis must be sure to call these interfaces appropriately.

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The deleteValue method

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The deleteValue method is called by transformations when they remove an instruction or any other value from the program (including values that do not use pointers). Typically alias analyses keep data structures that have entries @@ -487,7 +485,7 @@ any entries for the specified value, if they exist.

The copyValue method

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The copyValue method is used when a new value is introduced into the program. There is no way to introduce a value into the program that did not exist before (this doesn't make sense for a safe compiler transformation), so @@ -498,7 +496,7 @@ new value has exactly the same properties as the value being copied.

The replaceWithNewValue method

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This method is a simple helper method that is provided to make clients easier to use. It is implemented by copying the old analysis information to the new value, then deleting the old value. This method cannot be overridden by alias @@ -508,7 +506,7 @@ analysis implementations.

The addEscapingUse method

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The addEscapingUse method is used when the uses of a pointer value have changed in ways that may invalidate precomputed analysis information. Implementations may either use this callback to provide conservative responses @@ -527,12 +525,14 @@ uses below:

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Efficiency Issues

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From the LLVM perspective, the only thing you need to do to provide an efficient alias analysis is to make sure that alias analysis queries are @@ -548,7 +548,7 @@ method as possible (within reason).

Limitations -
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The AliasAnalysis infrastructure has several limitations which make writing a new AliasAnalysis implementation difficult.

@@ -616,25 +616,25 @@ from itself.

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Using alias analysis results

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There are several different ways to use alias analysis results. In order of preference, these are...

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Using the MemoryDependenceAnalysis Pass

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The memdep pass uses alias analysis to provide high-level dependence information about memory-using instructions. This will tell you which store @@ -649,7 +649,7 @@ efficient, and is used by Dead Store Elimination, GVN, and memcpy optimizations. Using the AliasSetTracker class -

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Many transformations need information about alias sets that are active in some scope, rather than information about pairwise aliasing. The -

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The AliasSetTracker implementation

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The AliasSetTracker class is implemented to be as efficient as possible. It uses the union-find algorithm to efficiently merge AliasSets when a pointer is @@ -706,12 +704,14 @@ are.

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Using the AliasAnalysis interface directly

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If neither of these utility class are what your pass needs, you should use the interfaces exposed by the AliasAnalysis class directly. Try to use @@ -721,13 +721,15 @@ best precision and efficiency.

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Existing alias analysis implementations and clients

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If you're going to be working with the LLVM alias analysis infrastructure, you should know what clients and implementations of alias analysis are @@ -735,28 +737,24 @@ available. In particular, if you are implementing an alias analysis, you should be aware of the the clients that are useful for monitoring and evaluating different implementations.

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Available AliasAnalysis implementations

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This section lists the various implementations of the AliasAnalysis interface. With the exception of the -no-aa and -basicaa implementations, all of these chain to other alias analysis implementations.

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The -no-aa pass

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The -no-aa pass is just like what it sounds: an alias analysis that never returns any useful information. This pass can be useful if you think that @@ -770,7 +768,7 @@ problem.

The -basicaa pass -
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The -basicaa pass is an aggressive local analysis that "knows" many important facts:

@@ -798,7 +796,7 @@ many important facts:

The -globalsmodref-aa pass -
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This pass implements a simple context-sensitive mod/ref and alias analysis for internal global variables that don't "have their address taken". If a @@ -822,7 +820,7 @@ non-address taken globals), but is very quick analysis.

The -steens-aa pass -
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The -steens-aa pass implements a variation on the well-known "Steensgaard's algorithm" for interprocedural alias analysis. Steensgaard's @@ -845,7 +843,7 @@ module, it is not part of the LLVM core.

The -ds-aa pass -
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The -ds-aa pass implements the full Data Structure Analysis algorithm. Data Structure Analysis is a modular unification-based, @@ -868,7 +866,7 @@ module, it is not part of the LLVM core.

The -scev-aa pass -
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The -scev-aa pass implements AliasAnalysis queries by translating them into ScalarEvolution queries. This gives it a @@ -877,22 +875,23 @@ and loop induction variables than other alias analyses have.

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Alias analysis driven transformations

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LLVM includes several alias-analysis driven transformations which can be used with any of the implementations above. -

The -adce pass

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The -adce pass, which implements Aggressive Dead Code Elimination uses the AliasAnalysis interface to delete calls to functions that do @@ -906,7 +905,7 @@ not have side-effects and are not used.

The -licm pass -
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The -licm pass implements various Loop Invariant Code Motion related transformations. It uses the AliasAnalysis interface for several @@ -931,7 +930,7 @@ no may aliases to the loaded/stored memory location. The -argpromotion pass -

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The -argpromotion pass promotes by-reference arguments to be passed in by-value instead. In particular, if pointer arguments are only loaded from it @@ -947,33 +946,33 @@ pointer.

passes -
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These passes use AliasAnalysis information to reason about loads and stores.

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Clients for debugging and evaluation of implementations

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These passes are useful for evaluating the various alias analysis implementations. You can use them with commands like 'opt -ds-aa -aa-eval foo.bc -disable-output -stats'.

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The -print-alias-sets pass

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The -print-alias-sets pass is exposed as part of the opt tool to print out the Alias Sets formed by the AliasSetTracker class. To use it, use something like:

The -count-aa pass -
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The -count-aa pass is useful to see how many queries a particular pass is making and what responses are returned by the alias analysis. As an @@ -1018,7 +1017,7 @@ when debugging a transformation or an alias analysis implementation.

The -aa-eval pass -
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The -aa-eval pass simply iterates through all pairs of pointers in a function and asks an alias analysis whether or not the pointers alias. This @@ -1028,13 +1027,17 @@ algorithm will have a lower number of may aliases).

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Memory Dependence Analysis

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If you're just looking to be a client of alias analysis information, consider using the Memory Dependence Analysis interface instead. MemDep is a lazy, diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html index cef80a48bcb..afee19b07e2 100644 --- a/docs/ReleaseNotes.html +++ b/docs/ReleaseNotes.html @@ -41,7 +41,7 @@ Release Notes. -

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This document contains the release notes for the LLVM Compiler Infrastructure, release 2.9. Here we describe the status of LLVM, including @@ -77,7 +77,7 @@ current one. To see the release notes for a specific release, please see the -

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The LLVM 2.9 distribution currently consists of code from the core LLVM repository (which roughly includes the LLVM optimizers, code generators @@ -86,15 +86,12 @@ addition to this code, the LLVM Project includes other sub-projects that are in development. Here we include updates on these subprojects.

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Clang: C/C++/Objective-C Frontend Toolkit

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Clang is an LLVM front end for the C, C++, and Objective-C languages. Clang aims to provide a better user experience @@ -125,7 +122,7 @@ compatibility guide to make sure this is not intentional or a known issue. DragonEgg: GCC front-ends, LLVM back-end -

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DragonEgg is a gcc plugin that replaces GCC's @@ -157,7 +154,7 @@ work yet. compiler-rt: Compiler Runtime Library -

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The new LLVM compiler-rt project is a simple library that provides an implementation of the low-level @@ -183,7 +180,7 @@ libgcc routines).

LLDB: Low Level Debugger -
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LLDB is a brand new member of the LLVM umbrella of projects. LLDB is a next generation, high-performance debugger. It @@ -205,7 +202,7 @@ GDB.

libc++: C++ Standard Library -
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libc++ is another new member of the LLVM family. It is an implementation of the C++ standard library, written from the @@ -230,7 +227,7 @@ Like compiler_rt, libc++ is now dual LLBrowse: IR Browser -

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LLBrowse is an interactive viewer for LLVM modules. It can load any LLVM @@ -245,7 +242,7 @@ Like compiler_rt, libc++ is now dual VMKit -

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The VMKit project is an implementation of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and just-in-time compilation. As of LLVM 2.9, VMKit now supports generational @@ -262,7 +259,7 @@ Like compiler_rt, libc++ is now dual KLEE: A Symbolic Execution Virtual Machine -

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KLEE is a symbolic execution framework for programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths @@ -274,6 +271,7 @@ be used to verify some algorithms.

UPDATE!

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@@ -281,18 +279,16 @@ be used to verify some algorithms.

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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 2.9.

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Crack Programming Language

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Crack aims to provide the ease of development of a scripting language with the performance of a compiled @@ -304,7 +300,7 @@ object-oriented programming, operator overloading and strong typing.

TTA-based Codesign Environment (TCE)

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TCE is a toolset for designing application-specific processors (ASP) based on the Transport triggered architecture (TTA). The toolset provides a complete co-design flow from C/C++ programs down to synthesizable VHDL and parallel @@ -323,7 +319,7 @@ of larger parts of the compiler chain.

PinaVM

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PinaVM is an open source, SystemC front-end. Unlike many other front-ends, PinaVM actually executes the elaboration of the @@ -334,7 +330,7 @@ bitcode with SystemC-specific information.

Pure

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Pure is an algebraic/functional programming language based on term rewriting. Programs are collections @@ -355,7 +351,7 @@ bitcode with SystemC-specific information.

IcedTea Java Virtual Machine Implementation

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IcedTea provides a harness to build OpenJDK using only free software build tools and to provide @@ -374,7 +370,7 @@ releases >= 2.6 as well).

Glasgow Haskell Compiler (GHC)

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GHC is an open source, state-of-the-art programming suite for Haskell, a standard lazy functional programming language. It includes an optimizing static compiler generating good code for a variety of @@ -388,7 +384,7 @@ supports an LLVM code generator. GHC supports LLVM 2.7 and later.

Polly - Polyhedral optimizations for LLVM

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Polly is a project that aims to provide advanced memory access optimizations to better take advantage of SIMD units, cache hierarchies, multiple cores or even vector accelerators for LLVM. Built around an abstract mathematical @@ -403,7 +399,7 @@ and parallelism.

Rubinius

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Rubinius is an environment for running Ruby code which strives to write as much of the implementation in Ruby as possible. Combined with a bytecode interpreting VM, it uses LLVM to @@ -418,7 +414,7 @@ and parallelism.

FAUST Real-Time Audio Signal Processing Language -
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FAUST is a compiled language for real-time audio signal processing. The name FAUST stands for Functional AUdio STream. Its @@ -428,27 +424,27 @@ Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7-2.9.

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What's New in LLVM 2.9?

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This release includes a huge number of bug fixes, performance tweaks and minor improvements. Some of the major improvements and new features are listed in this section.

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Major New Features

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LLVM 2.9 includes several major new capabilities:

@@ -478,7 +474,7 @@ in this section. LLVM IR and Core Improvements -
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LLVM IR has several new features for better support of new targets and that expose new optimization opportunities:

@@ -505,7 +501,7 @@ expose new optimization opportunities:

Optimizer Improvements -
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In addition to a large array of minor performance tweaks and bug fixes, this release includes a few major enhancements and additions to the optimizers:

@@ -573,7 +569,7 @@ release includes a few major enhancements and additions to the optimizers:

MC Level Improvements -
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The LLVM Machine Code (aka MC) subsystem was created to solve a number of problems in the realm of assembly, disassembly, object file format handling, @@ -627,7 +623,7 @@ LLVM MC Project Blog Post. Target Independent Code Generator Improvements -

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We have put a significant amount of work into the code generator infrastructure, which allows us to implement more aggressive algorithms and make @@ -670,7 +666,7 @@ it run faster:

X86-32 and X86-64 Target Improvements -
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New features and major changes in the X86 target include:

@@ -709,7 +705,7 @@ it run faster:

ARM Target Improvements -
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New features of the ARM target include:

@@ -733,7 +729,7 @@ it run faster:

Other Target Specific Improvements -
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  • MicroBlaze: major updates for aggressive delay slot filler, MC-based assembly printing, assembly instruction parsing, ELF .o file emission, and MC @@ -758,7 +754,7 @@ It also now supports lowering block addresses.
    • Major Changes and Removed Features -
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    If you're already an LLVM user or developer with out-of-tree changes based on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading @@ -794,7 +790,7 @@ from the previous release.

    Internal API Changes -
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    In addition, many APIs have changed in this release. Some of the major LLVM API changes are:

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Known Problems

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This section contains significant known problems with the LLVM system, listed by component. If you run into a problem, please check the LLVM bug database and submit a bug if there isn't already one.

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Experimental features included with this release

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The following components of this LLVM release are either untested, known to be broken or unreliable, or are in early development. These components should @@ -859,7 +855,7 @@ href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list.

Known problems with the X86 back-end -
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