1 ====================== 2 LLVM 3.9 Release Notes 3 ====================== 4 5 .. contents:: 6 :local: 7 8 .. warning:: 9 These are in-progress notes for the upcoming LLVM 3.9 release. You may 10 prefer the `LLVM 3.8 Release Notes <http://llvm.org/releases/3.8.0/docs 11 /ReleaseNotes.html>`_. 12 13 14 Introduction 15 ============ 16 17 This document contains the release notes for the LLVM Compiler Infrastructure, 18 release 3.9. 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.llvm.org/mailman/listinfo/llvm-dev>`_ 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 * The LLVMContext gains a new runtime check (see 37 LLVMContext::discardValueNames()) that can be set to discard Value names 38 (other than GlobalValue). This is intended to be used in release builds by 39 clients that are interested in saving CPU/memory as much as possible. 40 41 * There is no longer a "global context" available in LLVM, except for the C API. 42 43 * .. note about autoconf build having been removed. 44 45 * .. note about C API functions LLVMParseBitcode, 46 LLVMParseBitcodeInContext, LLVMGetBitcodeModuleInContext and 47 LLVMGetBitcodeModule having been removed. LLVMGetTargetMachineData has been 48 removed (use LLVMGetDataLayout instead). 49 50 * The C API function LLVMLinkModules has been removed. 51 52 * The C API function LLVMAddTargetData has been removed. 53 54 * The C API function LLVMGetDataLayout is deprecated 55 in favor of LLVMGetDataLayoutStr. 56 57 * The C API enum LLVMAttribute and associated API is deprecated in favor of 58 the new LLVMAttributeRef API. The deprecated functions are 59 LLVMAddFunctionAttr, LLVMAddTargetDependentFunctionAttr, 60 LLVMRemoveFunctionAttr, LLVMGetFunctionAttr, LLVMAddAttribute, 61 LLVMRemoveAttribute, LLVMGetAttribute, LLVMAddInstrAttribute, 62 LLVMRemoveInstrAttribute and LLVMSetInstrParamAlignment. 63 64 * ``TargetFrameLowering::eliminateCallFramePseudoInstr`` now returns an 65 iterator to the next instruction instead of ``void``. Targets that previously 66 did ``MBB.erase(I); return;`` now probably want ``return MBB.erase(I);``. 67 68 * ``SelectionDAGISel::Select`` now returns ``void``. Out of tree targets will 69 need to be updated to replace the argument node and remove any dead nodes in 70 cases where they currently return an ``SDNode *`` from this interface. 71 72 * Introduction of ThinLTO: [FIXME: needs to be documented more extensively in 73 /docs/ ; ping Mehdi/Teresa before the release if not done] 74 75 * Raised the minimum required CMake version to 3.4.3. 76 77 .. NOTE 78 For small 1-3 sentence descriptions, just add an entry at the end of 79 this list. If your description won't fit comfortably in one bullet 80 point (e.g. maybe you would like to give an example of the 81 functionality, or simply have a lot to talk about), see the `NOTE` below 82 for adding a new subsection. 83 84 * ... next change ... 85 86 .. NOTE 87 If you would like to document a larger change, then you can add a 88 subsection about it right here. You can copy the following boilerplate 89 and un-indent it (the indentation causes it to be inside this comment). 90 91 Special New Feature 92 ------------------- 93 94 Makes programs 10x faster by doing Special New Thing. 95 96 Changes to the LLVM IR 97 ---------------------- 98 99 * New intrinsics ``llvm.masked.load``, ``llvm.masked.store``, 100 ``llvm.masked.gather`` and ``llvm.masked.scatter`` were introduced to the 101 LLVM IR to allow selective memory access for vector data types. 102 103 Changes to LLVM's IPO model 104 --------------------------- 105 106 LLVM no longer does inter-procedural analysis and optimization (except 107 inlining) on functions with comdat linkage. Doing IPO over such 108 functions is unsound because the implementation the linker chooses at 109 link-time may be differently optimized than the one what was visible 110 during optimization, and may have arbitrarily different observable 111 behavior. See `PR26774 <http://llvm.org/PR26774>`_ for more details. 112 113 Changes to the ARM Backend 114 -------------------------- 115 116 During this release ... 117 118 119 Changes to the MIPS Target 120 -------------------------- 121 122 During this release ... 123 124 125 Changes to the PowerPC Target 126 ----------------------------- 127 128 Moved some optimizations from O3 to O2 (D18562) 129 130 * Enable sibling call optimization on ppc64 ELFv1/ELFv2 abi 131 132 Changes to the X86 Target 133 ------------------------- 134 135 * LLVM now supports the Intel CPU codenamed Skylake Server with AVX-512 136 extensions using ``-march=skylake-avx512``. The switch enables the 137 ISA extensions AVX-512{F, CD, VL, BW, DQ}. 138 139 * LLVM now supports the Intel CPU codenamed Knights Landing with AVX-512 140 extensions using ``-march=knl``. The switch enables the ISA extensions 141 AVX-512{F, CD, ER, PF}. 142 143 Changes to the AMDGPU Target 144 ----------------------------- 145 146 * Mesa 11.0.x is no longer supported 147 148 149 Changes to the OCaml bindings 150 ----------------------------- 151 152 During this release ... 153 154 Support for attribute 'notail' has been added 155 --------------------------------------------- 156 157 This marker prevents optimization passes from adding 'tail' or 158 'musttail' markers to a call. It is used to prevent tail call 159 optimization from being performed on the call. 160 161 External Open Source Projects Using LLVM 3.9 162 ============================================ 163 164 An exciting aspect of LLVM is that it is used as an enabling technology for 165 a lot of other language and tools projects. This section lists some of the 166 projects that have already been updated to work with LLVM 3.9. 167 168 * A project 169 170 171 Additional Information 172 ====================== 173 174 A wide variety of additional information is available on the `LLVM web page 175 <http://llvm.org/>`_, in particular in the `documentation 176 <http://llvm.org/docs/>`_ section. The web page also contains versions of the 177 API documentation which is up-to-date with the Subversion version of the source 178 code. You can access versions of these documents specific to this release by 179 going into the ``llvm/docs/`` directory in the LLVM tree. 180 181 If you have any questions or comments about LLVM, please feel free to contact 182 us via the `mailing lists <http://llvm.org/docs/#maillist>`_. 183 184
