1============================ 2LLVM |release| Release Notes 3============================ 4 5.. contents:: 6 :local: 7 8.. only:: PreRelease 9 10 .. warning:: 11 These are in-progress notes for the upcoming LLVM |version| release. 12 Release notes for previous releases can be found on 13 `the Download Page <https://releases.llvm.org/download.html>`_. 14 15 16Introduction 17============ 18 19This document contains the release notes for the LLVM Compiler Infrastructure, 20release |release|. Here we describe the status of LLVM, including major improvements 21from the previous release, improvements in various subprojects of LLVM, and 22some of the current users of the code. All LLVM releases may be downloaded 23from the `LLVM releases web site <https://llvm.org/releases/>`_. 24 25For more information about LLVM, including information about the latest 26release, please check out the `main LLVM web site <https://llvm.org/>`_. If you 27have questions or comments, the `LLVM Developer's Mailing List 28<https://lists.llvm.org/mailman/listinfo/llvm-dev>`_ is a good place to send 29them. 30 31Note that if you are reading this file from a Git checkout or the main 32LLVM web page, this document applies to the *next* release, not the current 33one. To see the release notes for a specific release, please see the `releases 34page <https://llvm.org/releases/>`_. 35 36Non-comprehensive list of changes in this release 37================================================= 38.. NOTE 39 For small 1-3 sentence descriptions, just add an entry at the end of 40 this list. If your description won't fit comfortably in one bullet 41 point (e.g. maybe you would like to give an example of the 42 functionality, or simply have a lot to talk about), see the `NOTE` below 43 for adding a new subsection. 44 45* ... 46 47Update on required toolchains to build LLVM 48------------------------------------------- 49 50With LLVM 15.x we will raise the version requirements of the toolchain used 51to build LLVM. The new requirements are as follows: 52 53* GCC >= 7.1 54* Clang >= 5.0 55* Apple Clang >= 9.3 56* Visual Studio 2019 >= 16.7 57 58In LLVM 15.x these requirements will be "soft" requirements and the version 59check can be skipped by passing -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=ON 60to CMake. 61 62With the release of LLVM 16.x these requirements will be hard and LLVM developers 63can start using C++17 features, making it impossible to build with older 64versions of these toolchains. 65 66Changes to the LLVM IR 67---------------------- 68 69Changes to building LLVM 70------------------------ 71 72* Omitting ``CMAKE_BUILD_TYPE`` when using a single configuration generator is now 73 an error. You now have to pass ``-DCMAKE_BUILD_TYPE=<type>`` in order to configure 74 LLVM. This is done to help new users of LLVM select the correct type: since building 75 LLVM in Debug mode is very resource intensive, we want to make sure that new users 76 make the choice that lines up with their usage. We have also improved documentation 77 around this setting that should help new users. You can find this documentation 78 `here <https://llvm.org/docs/CMake.html#cmake-build-type>`_. 79 80Changes to TableGen 81------------------- 82 83Changes to the AArch64 Backend 84------------------------------ 85 86Changes to the AMDGPU Backend 87----------------------------- 88 89* 8 and 16-bit atomic loads and stores are now supported 90 91 92Changes to the ARM Backend 93-------------------------- 94 95* Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures. 96* Added support for the Armv8.1-M PACBTI-M extension. 97* Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures. 98* Added support for the Armv8.1-M PACBTI-M extension. 99* Removed the deprecation of ARMv8-A T32 Complex IT blocks. No deprecation 100 warnings will be generated and -mrestrict-it is now always off by default. 101 Previously it was on by default for Armv8 and off for all other architecture 102 versions. 103* Added a pass to workaround Cortex-A57 Erratum 1742098 and Cortex-A72 104 Erratum 1655431. This is enabled by default when targeting either CPU. 105* Implemented generation of Windows SEH unwind information. 106* Switched the MinGW target to use SEH instead of DWARF for unwind information. 107 108Changes to the AVR Backend 109-------------------------- 110 111* ... 112 113Changes to the Hexagon Backend 114------------------------------ 115 116* ... 117 118Changes to the MIPS Backend 119--------------------------- 120 121* ... 122 123Changes to the PowerPC Backend 124------------------------------ 125 126* ... 127 128Changes to the RISC-V Backend 129----------------------------- 130 131* The Zvfh extension was added. 132 133Changes to the WebAssembly Backend 134---------------------------------- 135 136* ... 137 138Changes to the X86 Backend 139-------------------------- 140 141* Support ``half`` type on SSE2 and above targets. 142 143Changes to the OCaml bindings 144----------------------------- 145 146 147Changes to the C API 148-------------------- 149 150* Add ``LLVMGetCastOpcode`` function to aid users of ``LLVMBuildCast`` in 151 resolving the best cast operation given a source value and destination type. 152 This function is a direct wrapper of ``CastInst::getCastOpcode``. 153 154* Add ``LLVMGetAggregateElement`` function as a wrapper for 155 ``Constant::getAggregateElement``, which can be used to fetch an element of a 156 constant struct, array or vector, independently of the underlying 157 representation. The ``LLVMGetElementAsConstant`` function is deprecated in 158 favor of the new function, which works on all constant aggregates, rather than 159 only instances of ``ConstantDataSequential``. 160 161Changes to the Go bindings 162-------------------------- 163 164 165Changes to the FastISel infrastructure 166-------------------------------------- 167 168* ... 169 170Changes to the DAG infrastructure 171--------------------------------- 172 173 174Changes to the Debug Info 175--------------------------------- 176 177During this release ... 178 179Changes to the LLVM tools 180--------------------------------- 181 182Changes to LLDB 183--------------------------------- 184 185* The "memory region" command now has a "--all" option to list all 186 memory regions (including unmapped ranges). This is the equivalent 187 of using address 0 then repeating the command until all regions 188 have been listed. 189* Added "--show-tags" option to the "memory find" command. This is off by default. 190 When enabled, if the target value is found in tagged memory, the tags for that 191 memory will be shown inline with the memory contents. 192* Various memory related parts of LLDB have been updated to handle 193 non-address bits (such as AArch64 pointer signatures): 194 195 * "memory read", "memory write" and "memory find" can now be used with 196 addresses with non-address bits. 197 * All the read and write memory methods on SBProccess and SBTarget can 198 be used with addreses with non-address bits. 199 * When printing a pointer expression, LLDB can now dereference the result 200 even if it has non-address bits. 201 * The memory cache now ignores non-address bits when looking up memory 202 locations. This prevents us reading locations multiple times, or not 203 writing out new values if the addresses have different non-address bits. 204 205Changes to Sanitizers 206--------------------- 207 208 209Other Changes 210------------- 211* The code for the `LLVM Visual Studio integration 212 <https://marketplace.visualstudio.com/items?itemName=LLVMExtensions.llvm-toolchain>`_ 213 has been removed. This had been obsolete and abandoned since Visual Studio 214 started including an integration by default in 2019. 215 216External Open Source Projects Using LLVM 15 217=========================================== 218 219* A project... 220 221Additional Information 222====================== 223 224A wide variety of additional information is available on the `LLVM web page 225<https://llvm.org/>`_, in particular in the `documentation 226<https://llvm.org/docs/>`_ section. The web page also contains versions of the 227API documentation which is up-to-date with the Git version of the source 228code. You can access versions of these documents specific to this release by 229going into the ``llvm/docs/`` directory in the LLVM tree. 230 231If you have any questions or comments about LLVM, please feel free to contact 232us via the `mailing lists <https://llvm.org/docs/#mailing-lists>`_. 233