1 ====================== 2 LLVM 3.5 Release Notes 3 ====================== 4 5 .. contents:: 6 :local: 7 8 .. warning:: 9 These are in-progress notes for the upcoming LLVM 3.5 release. You may 10 prefer the `LLVM 3.4 Release Notes <http://llvm.org/releases/3.4/docs 11 /ReleaseNotes.html>`_. 12 13 14 Introduction 15 ============ 16 17 This document contains the release notes for the LLVM Compiler Infrastructure, 18 release 3.5. Here we describe the status of LLVM, including major improvements 19 from the previous release, improvements in various subprojects of LLVM, and 20 some of the current users of the code. All LLVM releases may be downloaded 21 from the `LLVM releases web site <http://llvm.org/releases/>`_. 22 23 For more information about LLVM, including information about the latest 24 release, please check out the `main LLVM web site <http://llvm.org/>`_. If you 25 have questions or comments, the `LLVM Developer's Mailing List 26 <http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_ is a good place to send 27 them. 28 29 Note that if you are reading this file from a Subversion checkout or the main 30 LLVM web page, this document applies to the *next* release, not the current 31 one. To see the release notes for a specific release, please see the `releases 32 page <http://llvm.org/releases/>`_. 33 34 Non-comprehensive list of changes in this release 35 ================================================= 36 37 * All backends have been changed to use the MC asm printer and support for the 38 non MC one has been removed. 39 40 * Clang can now successfully self-host itself on Linux/Sparc64 and on 41 FreeBSD/Sparc64. 42 43 * LLVM now assumes the assembler supports ``.loc`` for generating debug line 44 numbers. The old support for printing the debug line info directly was only 45 used by ``llc`` and has been removed. 46 47 * All inline assembly is parsed by the integrated assembler when it is enabled. 48 Previously this was only the case for object-file output. It is now the case 49 for assembly output as well. The integrated assembler can be disabled with 50 the ``-no-integrated-as`` option, 51 52 * llvm-ar now handles IR files like regular object files. In particular, a 53 regular symbol table is created for symbols defined in IR files, including 54 those in file scope inline assembly. 55 56 * LLVM now always uses cfi directives for producing most stack 57 unwinding information. 58 59 * The prefix for loop vectorizer hint metadata has been changed from 60 ``llvm.vectorizer`` to ``llvm.loop.vectorize``. 61 62 * Some backends previously implemented Atomic NAND(x,y) as ``x & ~y``. Now 63 all backends implement it as ``~(x & y)``, matching the semantics of GCC 4.4 64 and later. 65 66 .. NOTE 67 For small 1-3 sentence descriptions, just add an entry at the end of 68 this list. If your description won't fit comfortably in one bullet 69 point (e.g. maybe you would like to give an example of the 70 functionality, or simply have a lot to talk about), see the `NOTE` below 71 for adding a new subsection. 72 73 * ... next change ... 74 75 .. NOTE 76 If you would like to document a larger change, then you can add a 77 subsection about it right here. You can copy the following boilerplate 78 and un-indent it (the indentation causes it to be inside this comment). 79 80 Special New Feature 81 ------------------- 82 83 Makes programs 10x faster by doing Special New Thing. 84 85 Changes to the ARM Backend 86 -------------------------- 87 88 Since release 3.3, a lot of new features have been included in the ARM 89 back-end but weren't production ready (ie. well tested) on release 3.4. 90 Just after the 3.4 release, we started heavily testing two major parts 91 of the back-end: the integrated assembler (IAS) and the ARM exception 92 handling (EHABI), and now they are enabled by default on LLVM/Clang. 93 94 The IAS received a lot of GNU extensions and directives, as well as some 95 specific pre-UAL instructions. Not all remaining directives will be 96 implemented, as we made judgement calls on the need versus the complexity, 97 and have chosen simplicity and future compatibility where hard decisions 98 had to be made. The major difference is, as stated above, the IAS validates 99 all inline ASM, not just for object emission, and that cause trouble with 100 some uses of inline ASM as pre-processor magic. 101 102 So, while the IAS is good enough to compile large projects (including most 103 of the Linux kernel), there are a few things that we can't (and probably 104 won't) do. For those cases, please use ``-fno-integrated-as`` in Clang. 105 106 Exception handling is another big change. After extensive testing and 107 changes to cooperate with Dwarf unwinding, EHABI is enabled by default. 108 The options ``-arm-enable-ehabi`` and ``-arm-enable-ehabi-descriptors``, 109 which were used to enable EHABI in the previous releases, are removed now. 110 111 This means all ARM code will emit EH unwind tables, or CFI unwinding (for 112 debug/profiling), or both. To avoid run-time inconsistencies, C code will 113 also emit EH tables (in case they interoperate with C++ code), as is the 114 case for other architectures (ex. x86_64). 115 116 External Open Source Projects Using LLVM 3.5 117 ============================================ 118 119 An exciting aspect of LLVM is that it is used as an enabling technology for 120 a lot of other language and tools projects. This section lists some of the 121 projects that have already been updated to work with LLVM 3.5. 122 123 124 Additional Information 125 ====================== 126 127 A wide variety of additional information is available on the `LLVM web page 128 <http://llvm.org/>`_, in particular in the `documentation 129 <http://llvm.org/docs/>`_ section. The web page also contains versions of the 130 API documentation which is up-to-date with the Subversion version of the source 131 code. You can access versions of these documents specific to this release by 132 going into the ``llvm/docs/`` directory in the LLVM tree. 133 134 If you have any questions or comments about LLVM, please feel free to contact 135 us via the `mailing lists <http://llvm.org/docs/#maillist>`_. 136 137
