+
+
+Written by the LLVM Team
-This document contains the release notes for the LLVM Compiler - Infrastructure, release 3.0. Here we describe the status of LLVM, including - major improvements from the previous release and significant known problems. + Infrastructure, release 3.1. Here we describe the status of LLVM, including + major improvements from the previous release, improvements in various + subprojects of LLVM, and some of the current users of the code. All LLVM releases may be downloaded from the LLVM releases web site.
@@ -61,16 +62,8 @@ Release Notes. releases page.The LLVM 3.0 distribution currently consists of code from the core LLVM +
The LLVM 3.1 distribution currently consists of code from the core LLVM repository (which roughly includes the LLVM optimizers, code generators and supporting tools), and the Clang repository. In addition to this code, the LLVM Project includes other sub-projects that are @@ -99,37 +92,18 @@ Release Notes. provides a modular, library-based architecture that makes it suitable for creating or integrating with other development tools. Clang is considered a production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86 - (32- and 64-bit), and for darwin/arm targets.
- -In the LLVM 3.0 time-frame, the Clang team has made many improvements:
+ (32- and 64-bit), and for Darwin/ARM targets. +In the LLVM 3.1 time-frame, the Clang team has made many improvements:
For more details about the changes to Clang since the 2.9 release, see the +Clang release notes +
+ +If Clang rejects your code but another compiler accepts it, please take a look at the language compatibility guide to make sure this is not intentional or a known @@ -151,26 +125,12 @@ Release Notes. supports Ada, C, C++ and Fortran. It has partial support for Go, Java, Obj-C and Obj-C++.
-The 3.0 release has the following notable changes:
- -The 3.1 release has the following notable changes:
-In the LLVM 3.0 timeframe,
+....
@@ -202,11 +162,12 @@ Release Notes.LLDB has advanced by leaps and bounds in the 3.0 timeframe. It is - dramatically more stable and useful, and includes both a - new tutorial and - a side-by-side comparison with - GDB.
+LLDB is a ground-up implementation of a command line debugger, as well as a + debugger API that can be used from other applications. LLDB makes use of the + Clang parser to provide high-fidelity expression parsing (particularly for + C++) and uses the LLVM JIT for target support.
+ +...
- LLBrowse is an interactive viewer for LLVM modules. It can load any LLVM - module and displays its contents as an expandable tree view, facilitating an - easy way to inspect types, functions, global variables, or metadata nodes. It - is fully cross-platform, being based on the popular wxWidgets GUI - toolkit.
+...
In the LLVM 3.0 time-frame, VMKit has had significant improvements on both +
In the LLVM 3.1 time-frame, VMKit has had significant improvements on both runtime and startup performance:
Polly is an experimental + optimizer for data locality and parallelism. It currently provides high-level + loop optimizations and automatic parallelisation (using the OpenMP run time). + Work in the area of automatic SIMD and accelerator code generation was + started. + +
Within the LLVM 3.1 time-frame there were the following highlights:
+ +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 3.0.
- - -AddressSanitizer - uses compiler instrumentation and a specialized malloc library to find C/C++ - bugs such as use-after-free and out-of-bound accesses to heap, stack, and - globals. The key feature of the tool is speed: the average slowdown - introduced by AddressSanitizer is less than 2x.
- -Clam AntiVirus is an open source (GPL) - anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail - gateways.
- -Since version 0.96 it - has bytecode - signatures that allow writing detections for complex malware.
- -It uses LLVM's JIT to speed up the execution of bytecode on X86, X86-64, - PPC32/64, falling back to its own interpreter otherwise. The git version was - updated to work with LLVM 3.0.
- -clang_complete is a - VIM plugin, that provides accurate C/C++ autocompletion using the clang front - end. The development version of clang complete, can directly use libclang - which can maintain a cache to speed up auto completion.
- -clReflect is a C++ - parser that uses clang/LLVM to derive a light-weight reflection database - suitable for use in game development. It comes with a very simple runtime - library for loading and querying the database, requiring no external - dependencies (including CRT), and an additional utility library for object - management and serialisation.
- -Cling is an interactive compiler interface - (aka C++ interpreter). It uses LLVM's JIT and clang; it currently supports - C++ and C. It has a prompt interface, runs source files, calls into shared - libraries, prints the value of expressions, even does runtime lookup of - identifiers (dynamic scopes). And it just behaves like one would expect from - an interpreter.
- -Crack aims to provide - the ease of development of a scripting language with the performance of a - compiled language. The language derives concepts from C++, Java and Python, - incorporating object-oriented programming, operator overloading and strong - typing.
- -Eero is a fully - header-and-binary-compatible dialect of Objective-C 2.0, implemented with a - patched version of the Clang/LLVM compiler. It features a streamlined syntax, - Python-like indentation, and new operators, for improved readability and - reduced code clutter. It also has new features such as limited forms of - operator overloading and namespaces, and strict (type-and-operator-safe) - enumerations. It is inspired by languages such as Smalltalk, Python, and - Ruby.
- -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 platforms, together - with an interactive system for convenient, quick development.
- -GHC 7.0 and onwards include an LLVM code generator, supporting LLVM 2.8 and - later. Since LLVM 2.9, GHC now includes experimental support for the ARM - platform with LLVM 3.0.
- -gwXscript is an object oriented, - aspect oriented programming language which can create both executables (ELF, - EXE) and shared libraries (DLL, SO, DYNLIB). The compiler is implemented in - its own language and translates scripts into LLVM-IR which can be optimized - and translated into native code by the LLVM framework. Source code in - gwScript contains definitions that expand the namespaces. So you can build - your project and simply 'plug out' features by removing a file. The remaining - project does not leave scars since you directly separate concerns by the - 'template' feature of gwX. It is also possible to add new features to a - project by just adding files and without editing the original project. This - language is used for example to create games or content management systems - that should be extendable.
- -gwXscript is strongly typed and offers comfort with its native types string, - hash and array. You can easily write new libraries in gwXscript or native - code. gwXscript is type safe and users should not be able to crash your - program or execute malicious code except code that is eating CPU time.
- -include-what-you-use
- is a tool to ensure that a file directly #includes
- all .h files that provide a symbol that the file uses. It also
- removes superfluous #includes from source files.
ispc is a compiler for "single program, - multiple data" (SPMD) programs. It compiles a C-based SPMD programming - language to run on the SIMD units of CPUs; it often delivers 5-6x speedups on - a single core of a CPU with an 8-wide SIMD unit compared to serial code, - while still providing a clean and easy-to-understand programming model. For - an introduction to the language and its performance, - see the walkthrough of a short - example program. ispc is licensed under the BSD license.
- -LanguageKit is - a framework for implementing dynamic languages sharing an object model with - Objective-C. It provides static and JIT compilation using LLVM along with - its own interpreter. Pragmatic Smalltalk is a dialect of Smalltalk, built on - top of LanguageKit, that interfaces directly with Objective-C, sharing the - same object representation and message sending behaviour. These projects are - developed as part of the Étoié desktop environment.
- -LuaAV is a real-time - audiovisual scripting environment based around the Lua language and a - collection of libraries for sound, graphics, and other media protocols. LuaAV - uses LLVM and Clang to JIT compile efficient user-defined audio synthesis - routines specified in a declarative syntax.
- -An open source, cross-platform implementation of C# and the CLR that is - binary compatible with Microsoft.NET. Has an optional, dynamically-loaded - LLVM code generation backend in Mini, the JIT compiler.
- -Note that we use a Git mirror of LLVM with some patches. See: - https://github.com/mono/llvm
- -Polly is an advanced data-locality - optimizer and automatic parallelizer. It uses an advanced, mathematical - model to calculate detailed data dependency information which it uses to - optimize the loop structure of a program. Polly can speed up sequential code - by improving memory locality and consequently the cache use. Furthermore, - Polly is able to expose different kind of parallelism which it exploits by - introducing (basic) OpenMP and SIMD code. A mid-term goal of Polly is to - automatically create optimized GPU code.
- -Portable OpenCL is an open source implementation of the OpenCL standard which - can be easily adapted for new targets. One of the goals of the project is - improving performance portability of OpenCL programs, avoiding the need for - target-dependent manual optimizations. A "native" target is included, which - allows running OpenCL kernels on the host (CPU).
- -Pure is an - algebraic/functional programming language based on term rewriting. Programs - are collections of equations which are used to evaluate expressions in a - symbolic fashion. The interpreter uses LLVM as a backend to JIT-compile Pure - programs to fast native code. Pure offers dynamic typing, eager and lazy - evaluation, lexical closures, a hygienic macro system (also based on term - rewriting), built-in list and matrix support (including list and matrix - comprehensions) and an easy-to-use interface to C and other programming - languages (including the ability to load LLVM bitcode modules, and inline C, - C++, Fortran and Faust code in Pure programs if the corresponding LLVM-enabled - compilers are installed).
- -Pure version 0.48 has been tested and is known to work with LLVM 3.0 - (and continues to work with older LLVM releases >= 2.5).
- -Renderscript - is Android's advanced 3D graphics rendering and compute API. It provides a - portable C99-based language with extensions to facilitate common use cases - for enhancing graphics and thread level parallelism. The Renderscript - compiler frontend is based on Clang/LLVM. It emits a portable bitcode format - for the actual compiled script code, as well as reflects a Java interface for - developers to control the execution of the compiled bitcode. Executable - machine code is then generated from this bitcode by an LLVM backend on the - device. Renderscript is thus able to provide a mechanism by which Android - developers can improve performance of their applications while retaining - portability.
- -SAFECode is a memory safe C/C++ - compiler built using LLVM. It takes standard, unannotated C/C++ code, - analyzes the code to ensure that memory accesses and array indexing - operations are safe, and instruments the code with run-time checks when - safety cannot be proven statically. SAFECode can be used as a debugging aid - (like Valgrind) to find and repair memory safety bugs. It can also be used - to protect code from security attacks at run-time.
- -The Stupid D Compiler is a - project seeking to write a self-hosting compiler for the D programming - language without using the frontend of the reference compiler (DMD).
- -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 - program binaries. Processor customization points include the register files, - function units, supported operations, and the interconnection network.
- -TCE uses Clang and LLVM for C/C++ language support, target independent - optimizations and also for parts of code generation. It generates new - LLVM-based code generators "on the fly" for the designed TTA processors and - loads them in to the compiler backend as runtime libraries to avoid - per-target recompilation of larger parts of the compiler chain.
- -Tart is a general-purpose, - strongly typed programming language designed for application - developers. Strongly inspired by Python and C#, Tart focuses on practical - solutions for the professional software developer, while avoiding the clutter - and boilerplate of legacy languages like Java and C++. Although Tart is still - in development, the current implementation supports many features expected of - a modern programming language, such as garbage collection, powerful - bidirectional type inference, a greatly simplified syntax for template - metaprogramming, closures and function literals, reflection, operator - overloading, explicit mutability and immutability, and much more. Tart is - flexible enough to accommodate a broad range of programming styles and - philosophies, while maintaining a strong commitment to simplicity, minimalism - and elegance in design.
- -ThreadSanitizer is a - data race detector for (mostly) C and C++ code, available for Linux, Mac OS - and Windows. On different systems, we use binary instrumentation frameworks - (Valgrind and Pin) as frontends that generate the program events for the race - detection algorithm. On Linux, there's an option of using LLVM-based - compile-time instrumentation.
- -ZooLib is Open Source under the MIT - License. It provides GUI, filesystem access, TCP networking, thread-safe - memory management, threading and locking for Mac OS X, Classic Mac OS, - Microsoft Windows, POSIX operating systems with X11, BeOS, Haiku, Apple's iOS - and Research in Motion's BlackBerry.
- -My current work is to use CLang's static analyzer to improve ZooLib's code - quality. I also plan to set up LLVM compiles of the demo programs and test - programs using CLang and LLVM on all the platforms that CLang, LLVM and - ZooLib all support.
- -llvm-gcc is gone
+ -LLVM 3.0 includes several major new capabilities:
- - - - - -LLVM 3.1 includes several major changes and big features:
- - +LLVM IR has several new features for better support of new targets and that expose new optimization opportunities:
-One of the biggest changes is that 3.0 has a new exception handling
- system. The old system used LLVM intrinsics to convey the exception handling
- information to the code generator. It worked in most cases, but not
- all. Inlining was especially difficult to get right. Also, the intrinsics
- could be moved away from the invoke instruction, making it hard
- to recover that information.
The new EH system makes exception handling a first-class member of the IR. It - adds two new instructions:
- -landingpad —
- this instruction defines a landing pad basic block. It contains all of the
- information that's needed by the code generator. It's also required to be
- the first non-PHI instruction in the landing pad. In addition, a landing
- pad may be jumped to only by the unwind edge of an invoke
- instruction.resume — this
- instruction causes the current exception to resume traveling up the
- stack. It replaces the @llvm.eh.resume intrinsic.Converting from the old EH API to the new EH API is rather simple, because a
- lot of complexity has been removed. The two intrinsics,
- @llvm.eh.exception and @llvm.eh.selector have been
- superceded by the landingpad instruction. Instead of generating
- a call to @llvm.eh.exception and @llvm.eh.selector:
-
-
-Function *ExcIntr = Intrinsic::getDeclaration(TheModule, - Intrinsic::eh_exception); -Function *SlctrIntr = Intrinsic::getDeclaration(TheModule, - Intrinsic::eh_selector); - -// The exception pointer. -Value *ExnPtr = Builder.CreateCall(ExcIntr, "exc_ptr"); - -std::vector<Value*> Args; -Args.push_back(ExnPtr); -Args.push_back(Builder.CreateBitCast(Personality, - Type::getInt8PtrTy(Context))); - -// Add selector clauses to Args. - -// The selector call. -Builder.CreateCall(SlctrIntr, Args, "exc_sel"); --
You should instead generate a landingpad instruction, that
- returns an exception object and selector value:
-LandingPadInst *LPadInst = - Builder.CreateLandingPad(StructType::get(Int8PtrTy, Int32Ty, NULL), - Personality, 0); - -Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0); -Builder.CreateStore(LPadExn, getExceptionSlot()); - -Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1); -Builder.CreateStore(LPadSel, getEHSelectorSlot()); --
It's now trivial to add the individual clauses to the landingpad
- instruction.
-// Adding a catch clause -Constant *TypeInfo = getTypeInfo(); -LPadInst->addClause(TypeInfo); - -// Adding a C++ catch-all -LPadInst->addClause(Constant::getNullValue(Builder.getInt8PtrTy())); - -// Adding a cleanup -LPadInst->setCleanup(true); - -// Adding a filter clause -std::vector<Constant*> TypeInfos; -Constant *TypeInfo = getFilterTypeInfo(); -TypeInfos.push_back(Builder.CreateBitCast(TypeInfo, Builder.getInt8PtrTy())); - -ArrayType *FilterTy = ArrayType::get(Int8PtrTy, TypeInfos.size()); -LPadInst->addClause(ConstantArray::get(FilterTy, TypeInfos)); --
Converting from using the @llvm.eh.resume intrinsic to
- the resume instruction is trivial. It takes the exception
- pointer and exception selector values returned by
- the landingpad instruction:
-Type *UnwindDataTy = StructType::get(Builder.getInt8PtrTy(), - Builder.getInt32Ty(), NULL); -Value *UnwindData = UndefValue::get(UnwindDataTy); -Value *ExcPtr = Builder.CreateLoad(getExceptionObjSlot()); -Value *ExcSel = Builder.CreateLoad(getExceptionSelSlot()); -UnwindData = Builder.CreateInsertValue(UnwindData, ExcPtr, 0, "exc_ptr"); -UnwindData = Builder.CreateInsertValue(UnwindData, ExcSel, 1, "exc_sel"); -Builder.CreateResume(UnwindData); --
The induction variable simplification pass in 3.0 only modifies - induction variables when profitable. Sign and zero extension - elimination, linear function test replacement, loop unrolling, and - other simplifications that require induction variable analysis have - been generalized so they no longer require loops to be rewritten in a - typically suboptimal form prior to optimization. This new design - preserves more IR level information, avoids undoing earlier loop - optimizations (particularly hand-optimized loops), and no longer - strongly depends on the code generator rewriting loops a second time - in a now optimal form--an intractable problem.
- -The original behavior can be restored with -mllvm -enable-iv-rewrite; - however, support for this mode will be short lived. As such, bug - reports should be filed for any significant performance regressions - when moving from -mllvm -enable-iv-rewrite to the 3.0 default mode.
+In addition to a large array of minor performance tweaks and bug fixes, this +
In addition to many minor performance tweaks and bug fixes, this release includes a few major enhancements and additions to the optimizers:
-unroll-runtime flag.-vectorize to run this pass along with some associated
+ post-vectorization cleanup passes. For more information, see the EuroLLVM
+ 2012 slides:
+ Autovectorization with LLVM.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, and a number of other related areas that CPU instruction-set level tools work - in.
+ in. For more information, please see + the Intro + to the LLVM MC Project Blog Post.For more information, please see - the Intro - to the LLVM MC Project Blog Post.
- @@ -948,15 +383,52 @@ Builder.CreateResume(UnwindData);We have changed the way that the Type Legalizer legalizes vectors. The type + legalizer now attempts to promote integer elements. This enabled the + implementation of vector-select. Additionally, we see a performance boost on + workloads which use vectors of chars and shorts, since they are now promoted + to 32-bit types, which are better supported by the SIMD instruction set. + Floating point types are still widened as before.
+ +We have put a significant amount of work into the code generator infrastructure, which allows us to implement more aggressive algorithms and make it run faster:
MachineRegisterInfo now allows the reserved registers to be
+ frozen when register allocation starts. Target hooks should use the
+ MRI->canReserveReg(FramePtr) method to avoid accidentally
+ disabling frame pointer elimination during register allocation.MachineOperand provides a compact
+ representation of large clobber lists on call instructions. The register
+ mask operand references a bit mask of preserved registers. Everything else
+ is clobbered.We added new TableGen infrastructure to support bundling for + Very Long Instruction Word (VLIW) architectures. TableGen can now + automatically generate a deterministic finite automaton from a VLIW + target's schedule description which can be queried to determine + legal groupings of instructions in a bundle.
+ +We have added a new target independent VLIW packetizer based on the + DFA infrastructure to group machine instructions into bundles.
+ +A probability based block placement and code layout algorithm was added to
+LLVM's code generator. This layout pass supports probabilities derived from
+static heuristics as well as source code annotations such as
+__builtin_expect.
New features and major changes in the X86 target include:
@llvm.x86.sse42.crc32.[8|16|32]
- and @llvm.x86.sse42.crc64.[8|64]. They have been renamed to
- @llvm.x86.sse42.crc32.32.[8|16|32] and
- @llvm.x86.sse42.crc32.64.[8|64].New features of the ARM target include:
The ARM target now includes a full featured macro assembler, including +direct-to-object module support for clang. The assembler is currently enabled +by default for Darwin only pending testing and any additional necessary +platform specific support for Linux.
+ +Full support is included for Thumb1, Thumb2 and ARM modes, along with +subtarget and CPU specific extensions for VFP2, VFP3 and NEON.
+ +The assembler is Unified Syntax only (see ARM Architecural Reference Manual +for details). While there is some, and growing, support for pre-unfied (divided) +syntax, there are still significant gaps in that support.
+New features and major changes in the MIPS target include:
+This release has seen major new work on just about every aspect of the MIPS + backend. Some of the major new features include:
PPC32/ELF va_arg was implemented.
-PPC32 initial support for .o file writing was implemented.
-MicroBlaze scheduling itineraries were added that model the
- 3-stage and the 5-stage pipeline architectures. The 3-stage
- pipeline model can be selected with -mcpu=mblaze3
- and the 5-stage pipeline model can be selected with
- -mcpu=mblaze5.
Support for Qualcomm's Hexagon VLIW processor has been added.
+If you're already an LLVM user or developer with out-of-tree changes based on - LLVM 2.9, this section lists some "gotchas" that you may run into upgrading + LLVM 3.1, this section lists some "gotchas" that you may run into upgrading from the previous release.
LLVMC front end code was removed while separating
- out language independence.LowerSetJmp pass wasn't used effectively by any
- target and has been removed.TailDup pass was not used in the standard pipeline
- and was unable to update ssa form, so it has been removed.
- load volatile"/"store volatile". The old
- syntax ("volatile load"/"volatile store")
- is still accepted, but is now considered deprecated.llvm.memory.barrier and
- llvm.atomic.*) are now gone. Please use the new atomic
- instructions, described in the atomics guide.
+ PHINode::reserveOperandSpace has been removed. Instead, you
- must specify how many operands to reserve space for when you create the
- PHINode, by passing an extra argument
- into PHINode::Create.PHINode::block_begin
- and PHINode::block_end.ArrayRef instead of either a
- pair of pointers (or iterators) to the beginning and end of a range, or a
- pointer and a length. Others now return an ArrayRef instead
- of a reference to a SmallVector
- or std::vector. These include:
+ TargetOptions class, which is local to each
+ TargetMachine. As a consequence, the associated flags will
+ no longer be accepted by clang -mllvm. This includes:
CallInst::CreateComputeLinearIndex (in llvm/CodeGen/Analysis.h)ConstantArray::getConstantExpr::getExtractElementConstantExpr::getGetElementPtrConstantExpr::getInBoundsGetElementPtrConstantExpr::getIndicesConstantExpr::getInsertElementConstantExpr::getWithOperandsConstantFoldCall (in llvm/Analysis/ConstantFolding.h)ConstantFoldInstOperands (in llvm/Analysis/ConstantFolding.h)ConstantVector::getDIBuilder::createComplexVariableDIBuilder::getOrCreateArrayExtractValueInst::CreateExtractValueInst::getIndexedTypeExtractValueInst::getIndicesFindInsertedValue (in llvm/Analysis/ValueTracking.h)gep_type_begin (in llvm/Support/GetElementPtrTypeIterator.h)gep_type_end (in llvm/Support/GetElementPtrTypeIterator.h)GetElementPtrInst::CreateGetElementPtrInst::CreateInBoundsGetElementPtrInst::getIndexedTypeInsertValueInst::CreateInsertValueInst::getIndicesInvokeInst::CreateIRBuilder::CreateCallIRBuilder::CreateExtractValueIRBuilder::CreateGEPIRBuilder::CreateInBoundsGEPIRBuilder::CreateInsertValueIRBuilder::CreateInvokeMDNode::getMDNode::getIfExistsMDNode::getTemporaryMDNode::getWhenValsUnresolvedSimplifyGEPInst (in llvm/Analysis/InstructionSimplify.h)TargetData::getIndexedOffsetllvm::PrintMachineCodellvm::NoFramePointerElimllvm::NoFramePointerElimNonLeafllvm::DisableFramePointerElim(const MachineFunction &)llvm::LessPreciseFPMADOptionllvm::LessPrecideFPMAD()llvm::NoExcessFPPrecisionllvm::UnsafeFPMathllvm::NoInfsFPMathllvm::NoNaNsFPMathllvm::HonorSignDependentRoundingFPMathOptionllvm::HonorSignDependentRoundingFPMath()llvm::UseSoftFloatllvm::FloatABITypellvm::NoZerosInBSSllvm::JITExceptionHandlingllvm::JITEmitDebugInfollvm::JITEmitDebugInfoToDiskllvm::GuaranteedTailCallOptllvm::StackAlignmentOverridellvm::RealignStackllvm::DisableJumpTablesllvm::EnableFastISelllvm::getTrapFunctionName()llvm::EnableSegmentedStacksStringMap::getOrCreateValue have been remove
- except for the one which takes a StringRef.LLVMBuildUnwind function from the C API was removed. The
- LLVM unwind instruction has been deprecated for a long time
- and isn't used by the current front-ends. So this was removed during the
- exception handling rewrite.LLVMAddLowerSetJmpPass function from the C API was
- removed because the LowerSetJmp pass was removed.DIBuilder interface used by front ends to encode
- debugging information in the LLVM IR now expects clients to
- use DIBuilder::finalize() at the end of translation unit to
- complete debugging information encoding.PATypeHolder and OpaqueType are gone,
- and all APIs deal with Type* instead of const
- Type*. If you need to create recursive structures, then create a
- named structure, and use setBody() when all its elements are
- built. Type merging and refining is gone too: named structures are not
- merged with other structures, even if their layout is identical. (of
- course anonymous structures are still uniqued by layout).llvm.memset.i32).INITIALIZE_PASS{BEGIN,END,}
- and INITIALIZE_{PASS,AG}_DEPENDENCY.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.
- - -The following components of this LLVM release are either untested, known to - be broken or unreliable, or are in early development. These components - should not be relied on, and bugs should not be filed against them, but they - may be useful to some people. In particular, if you would like to work on - one of these components, please contact us on - the LLVMdev - list.
- -In addition, some tools have changed in this release. Some of the changes + are:
- -LLVM is generally a production quality compiler, and is used by a broad range + of applications and shipping in many products. That said, not every + subsystem is as mature as the aggregate, particularly the more obscure + targets. If you run into a problem, please check the LLVM bug database and submit a bug if + there isn't already one or ask on the LLVMdev + list.
-The C backend has numerous problems and is not being actively maintained. - Depending on it for anything serious is not advised.
+Known problem areas include: