1====================== 2LLVM 3.4 Release Notes 3====================== 4 5.. contents:: 6 :local: 7 8Introduction 9============ 10 11This document contains the release notes for the LLVM Compiler Infrastructure, 12release 3.4. Here we describe the status of LLVM, including major improvements 13from the previous release, improvements in various subprojects of LLVM, and 14some of the current users of the code. All LLVM releases may be downloaded 15from the `LLVM releases web site <http://llvm.org/releases/>`_. 16 17For more information about LLVM, including information about the latest 18release, please check out the `main LLVM web site <http://llvm.org/>`_. If you 19have questions or comments, the `LLVM Developer's Mailing List 20<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_ is a good place to send 21them. 22 23Note that if you are reading this file from a Subversion checkout or the main 24LLVM web page, this document applies to the *next* release, not the current 25one. To see the release notes for a specific release, please see the `releases 26page <http://llvm.org/releases/>`_. 27 28Non-comprehensive list of changes in this release 29================================================= 30 31.. NOTE 32 For small 1-3 sentence descriptions, just add an entry at the end of 33 this list. If your description won't fit comfortably in one bullet 34 point (e.g. maybe you would like to give an example of the 35 functionality, or simply have a lot to talk about), see the `NOTE` below 36 for adding a new subsection. 37 38* This is expected to be the last release of LLVM which compiles using a C++98 39 toolchain. We expect to start using some C++11 features in LLVM and other 40 sub-projects starting after this release. That said, we are committed to 41 supporting a reasonable set of modern C++ toolchains as the host compiler on 42 all of the platforms. This will at least include Visual Studio 2012 on 43 Windows, and Clang 3.1 or GCC 4.7.x on Mac and Linux. The final set of 44 compilers (and the C++11 features they support) is not set in stone, but we 45 wanted users of LLVM to have a heads up that the next release will involve 46 a substantial change in the host toolchain requirements. 47 48* The regression tests now fail if any command in a pipe fails. To disable it in 49 a directory, just add ``config.pipefail = False`` to its ``lit.local.cfg``. 50 See :doc:`Lit <CommandGuide/lit>` for the details. 51 52* Support for exception handling has been removed from the old JIT. Use MCJIT 53 if you need EH support. 54 55* The R600 backend is not marked experimental anymore and is built by default. 56 57* APFloat::isNormal() was renamed to APFloat::isFiniteNonZero() and 58 APFloat::isIEEENormal() was renamed to APFloat::isNormal(). This ensures that 59 APFloat::isNormal() conforms to IEEE-754R-2008. 60 61* The library call simplification pass has been removed. Its functionality 62 has been integrated into the instruction combiner and function attribute 63 marking passes. 64 65* Support for building using Visual Studio 2008 has been dropped. Use VS 2010 66 or later instead. For more information, see the `Getting Started using Visual 67 Studio <GettingStartedVS.html>`_ page. 68 69* The Loop Vectorizer that was previously enabled for -O3 is now enabled for 70 -Os and -O2. 71 72* The new SLP Vectorizer is now enabled by default. 73 74* llvm-ar now uses the new Object library and produces archives and 75 symbol tables in the gnu format. 76 77* FileCheck now allows specifing -check-prefix multiple times. This 78 helps reduce duplicate check lines when using multiple RUN lines. 79 80* The bitcast instruction no longer allows casting between pointers 81 with different address spaces. To achieve this, use the new 82 addrspacecast instruction. 83 84* Different sized pointers for different address spaces should now 85 generally work. This is primarily useful for GPU targets. 86 87* ... next change ... 88 89.. NOTE 90 If you would like to document a larger change, then you can add a 91 subsection about it right here. You can copy the following boilerplate 92 and un-indent it (the indentation causes it to be inside this comment). 93 94 Special New Feature 95 ------------------- 96 97 Makes programs 10x faster by doing Special New Thing. 98 99Mips Target 100----------- 101 102Support for the MIPS SIMD Architecture (MSA) has been added. MSA is supported 103through inline assembly, intrinsics with the prefix '__builtin_msa', and normal 104code generation. 105 106For more information on MSA (including documentation for the instruction set), 107see the `MIPS SIMD page at Imagination Technologies 108<http://imgtec.com/mips/mips-simd.asp>`_ 109 110External Open Source Projects Using LLVM 3.4 111============================================ 112 113An exciting aspect of LLVM is that it is used as an enabling technology for 114a lot of other language and tools projects. This section lists some of the 115projects that have already been updated to work with LLVM 3.4. 116 117DXR 118--- 119 120`DXR <https://wiki.mozilla.org/DXR>`_ is Mozilla's code search and navigation 121tool, aimed at making sense of large projects like Firefox. It supports 122full-text and regex searches as well as structural queries like "Find all the 123callers of this function." Behind the scenes, it uses a custom trigram index, 124the re2 library, and structural data collected by a clang compiler plugin. 125 126LDC - the LLVM-based D compiler 127------------------------------- 128 129`D <http://dlang.org>`_ is a language with C-like syntax and static typing. It 130pragmatically combines efficiency, control, and modeling power, with safety and 131programmer productivity. D supports powerful concepts like Compile-Time Function 132Execution (CTFE) and Template Meta-Programming, provides an innovative approach 133to concurrency and offers many classical paradigms. 134 135`LDC <http://wiki.dlang.org/LDC>`_ uses the frontend from the reference compiler 136combined with LLVM as backend to produce efficient native code. LDC targets 137x86/x86_64 systems like Linux, OS X, FreeBSD and Windows and also Linux/PPC64. 138Ports to other architectures like ARM and AArch64 are underway. 139 140Likely 141------ 142 143`Likely <http://www.liblikely.org/>`_ is an open source domain specific 144language for image recognition. Algorithms are just-in-time compiled using 145LLVM's MCJIT infrastructure to execute on single or multi-threaded CPUs as well 146as OpenCL SPIR or CUDA enabled GPUs. Likely exploits the observation that while 147image processing and statistical learning kernels must be written generically 148to handle any matrix datatype, at runtime they tend to be executed repeatedly 149on the same type. 150 151Portable Computing Language (pocl) 152---------------------------------- 153 154In addition to producing an easily portable open source OpenCL 155implementation, another major goal of `pocl <http://portablecl.org/>`_ 156is improving performance portability of OpenCL programs with 157compiler optimizations, reducing the need for target-dependent manual 158optimizations. An important part of pocl is a set of LLVM passes used to 159statically parallelize multiple work-items with the kernel compiler, even in 160the presence of work-group barriers. This enables static parallelization of 161the fine-grained static concurrency in the work groups in multiple ways. 162 163TTA-based Co-design Environment (TCE) 164------------------------------------- 165 166`TCE <http://tce.cs.tut.fi/>`_ is a toolset for designing new 167exposed datapath processors based on the Transport triggered architecture (TTA). 168The toolset provides a complete co-design flow from C/C++ 169programs down to synthesizable VHDL/Verilog and parallel program binaries. 170Processor customization points include the register files, function units, 171supported operations, and the interconnection network. 172 173TCE uses Clang and LLVM for C/C++/OpenCL C language support, target independent 174optimizations and also for parts of code generation. It generates 175new LLVM-based code generators "on the fly" for the designed processors and 176loads them in to the compiler backend as runtime libraries to avoid 177per-target recompilation of larger parts of the compiler chain. 178 179WebCL Validator 180--------------- 181 182`WebCL Validator <https://github.com/KhronosGroup/webcl-validator>`_ implements 183validation for WebCL C language which is a subset of OpenCL ES 1.1. Validator 184checks the correctness of WebCL C, and implements memory protection for it as a 185source-2-source transformation. The transformation converts WebCL to memory 186protected OpenCL. The protected OpenCL cannot access any memory ranges which 187were not allocated for it, and its memory is always initialized to prevent 188information leakage from other programs. 189 190 191Additional Information 192====================== 193 194A wide variety of additional information is available on the `LLVM web page 195<http://llvm.org/>`_, in particular in the `documentation 196<http://llvm.org/docs/>`_ section. The web page also contains versions of the 197API documentation which is up-to-date with the Subversion version of the source 198code. You can access versions of these documents specific to this release by 199going into the ``llvm/docs/`` directory in the LLVM tree. 200 201If you have any questions or comments about LLVM, please feel free to contact 202us via the `mailing lists <http://llvm.org/docs/#maillist>`_. 203 204