============================ LLVM |release| Release Notes ============================ .. contents:: :local: .. only:: PreRelease .. warning:: These are in-progress notes for the upcoming LLVM |version| release. Release notes for previous releases can be found on `the Download Page `_. Introduction ============ This document contains the release notes for the LLVM Compiler Infrastructure, release |release|. 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 `_. For more information about LLVM, including information about the latest release, please check out the `main LLVM web site `_. If you have questions or comments, the `LLVM Developer's Mailing List `_ is a good place to send them. Note that if you are reading this file from a Git checkout or the main LLVM web page, this document applies to the *next* release, not the current one. To see the release notes for a specific release, please see the `releases page `_. Non-comprehensive list of changes in this release ================================================= .. NOTE For small 1-3 sentence descriptions, just add an entry at the end of this list. If your description won't fit comfortably in one bullet point (e.g. maybe you would like to give an example of the functionality, or simply have a lot to talk about), see the `NOTE` below for adding a new subsection. * ... Update on required toolchains to build LLVM ------------------------------------------- With LLVM 15.x we will raise the version requirements of the toolchain used to build LLVM. The new requirements are as follows: * GCC >= 7.1 * Clang >= 5.0 * Apple Clang >= 9.3 * Visual Studio 2019 >= 16.7 In LLVM 15.x these requirements will be "soft" requirements and the version check can be skipped by passing -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=ON to CMake. With the release of LLVM 16.x these requirements will be hard and LLVM developers can start using C++17 features, making it impossible to build with older versions of these toolchains. Changes to the LLVM IR ---------------------- Changes to building LLVM ------------------------ * Omitting ``CMAKE_BUILD_TYPE`` when using a single configuration generator is now an error. You now have to pass ``-DCMAKE_BUILD_TYPE=`` in order to configure LLVM. This is done to help new users of LLVM select the correct type: since building LLVM in Debug mode is very resource intensive, we want to make sure that new users make the choice that lines up with their usage. We have also improved documentation around this setting that should help new users. You can find this documentation `here `_. Changes to TableGen ------------------- Changes to the AArch64 Backend ------------------------------ Changes to the AMDGPU Backend ----------------------------- * 8 and 16-bit atomic loads and stores are now supported Changes to the ARM Backend -------------------------- * Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures. * Added support for the Armv8.1-M PACBTI-M extension. * Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures. * Added support for the Armv8.1-M PACBTI-M extension. * Removed the deprecation of ARMv8-A T32 Complex IT blocks. No deprecation warnings will be generated and -mrestrict-it is now always off by default. Previously it was on by default for Armv8 and off for all other architecture versions. * Added a pass to workaround Cortex-A57 Erratum 1742098 and Cortex-A72 Erratum 1655431. This is enabled by default when targeting either CPU. Changes to the AVR Backend -------------------------- * ... Changes to the Hexagon Backend ------------------------------ * ... Changes to the MIPS Backend --------------------------- * ... Changes to the PowerPC Backend ------------------------------ * ... Changes to the RISC-V Backend ----------------------------- * The Zvfh extension was added. Changes to the WebAssembly Backend ---------------------------------- * ... Changes to the X86 Backend -------------------------- * ... Changes to the OCaml bindings ----------------------------- Changes to the C API -------------------- * Add ``LLVMGetCastOpcode`` function to aid users of ``LLVMBuildCast`` in resolving the best cast operation given a source value and destination type. This function is a direct wrapper of ``CastInst::getCastOpcode``. Changes to the Go bindings -------------------------- Changes to the FastISel infrastructure -------------------------------------- * ... Changes to the DAG infrastructure --------------------------------- Changes to the Debug Info --------------------------------- During this release ... Changes to the LLVM tools --------------------------------- Changes to LLDB --------------------------------- * The "memory region" command now has a "--all" option to list all memory regions (including unmapped ranges). This is the equivalent of using address 0 then repeating the command until all regions have been listed. * Added "--show-tags" option to the "memory find" command. This is off by default. When enabled, if the target value is found in tagged memory, the tags for that memory will be shown inline with the memory contents. * Various memory related parts of LLDB have been updated to handle non-address bits (such as AArch64 pointer signatures): * "memory read", "memory write" and "memory find" can now be used with addresses with non-address bits. * All the read and write memory methods on SBProccess and SBTarget can be used with addreses with non-address bits. * When printing a pointer expression, LLDB can now dereference the result even if it has non-address bits. * The memory cache now ignores non-address bits when looking up memory locations. This prevents us reading locations multiple times, or not writing out new values if the addresses have different non-address bits. Changes to Sanitizers --------------------- Other Changes ------------- * The code for the `LLVM Visual Studio integration `_ has been removed. This had been obsolete and abandoned since Visual Studio started including an integration by default in 2019. External Open Source Projects Using LLVM 15 =========================================== * A project... Additional Information ====================== A wide variety of additional information is available on the `LLVM web page `_, in particular in the `documentation `_ section. The web page also contains versions of the API documentation which is up-to-date with the Git version of the source code. You can access versions of these documents specific to this release by going into the ``llvm/docs/`` directory in the LLVM tree. If you have any questions or comments about LLVM, please feel free to contact us via the `mailing lists `_.