LLVM 13.0.0 Release Notes


This document contains the release notes for the LLVM Compiler Infrastructure, release 13.0.0. 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

  • Windows Control-flow Enforcement Technology: the -ehcontguard option now emits valid unwind entrypoints which are validated when the context is being set during exception handling.

  • Flang is now included in the binary packages released by LLVM.

  • The debuginfo-test project has been renamed cross-project-tests and is now intended for testing components from multiple projects, not just debug information. The new “cross-project-tests” name replaces “debuginfo-test” in LLVM_ENABLE_PROJECTS, and a new check-cross-project-tests target has been added for running all tests in the project. The pre-existing check-debuginfo- test target remains for running just the debug information tests. (D95339 and D96513)

Changes to the LLVM IR

  • The inalloca attribute now has a mandatory type field, similar to byval and sret.

  • The opaque pointer type ptr has been introduced. It is still in the process of being worked on and should not be used yet.

  • Using the legacy pass manager for the optimization pipeline is deprecated and will be removed after LLVM 14. In the meantime, only minimal effort will be made to maintain the legacy pass manager for the optimization pipeline.

Changes to building LLVM

  • The build system now supports building multiple distributions, so that you can e.g. have one distribution containing just tools and another for libraries (to enable development). See Multi-distribution configurations for details.

Changes to the AArch64 Backend

  • Introduced assembly support for Armv9-A’s Realm Management Extension (RME) and Scalable Matrix Extension (SME).

  • Produce proper cross-section relative relocations on COFF

  • Fixed the calling convention on Windows for variadic functions involving floats in the fixed arguments

Changes to the ARM Backend

  • Produce proper cross-section relative relocations on COFF

Changes to the MIPS Target

During this release …

Changes to the Hexagon Target

  • The Hexagon target now supports V68/HVX ISA.

Changes to the PowerPC Target

During this release …

Changes to the X86 Target

During this release …

Changes to the AMDGPU Target

During this release …

Changes to the AVR Target

During this release …

Changes to the WebAssembly Target

During this release …

Changes to the C API

  • The C API functions LLVMGetAlignment and LLVMSetAlignment now allow changing alignment on atomicrmw and cmpxchg instructions

  • A new entry LLVMDIArgListMetadataKind was added to the LLVMMetadataKind enum, representing DIArgLists (D88175)

  • Type attributes have been added to LLVM-C, introducing LLVMCreateTypeAttribute, LLVMGetTypeAttributeValue and LLVMIsTypeAttribute. (D977763’)

  • The LTO_API_VERSION was bumped to 28, introducing a new function lto_set_debug_options for parsing LTO debug options (D92611)

  • LLVMJITTargetSymbolFlags was renamed to LLVMJITSymbolTargetFlags (rG8d718a0bff73af066675a6258c01307937c33cf9)

  • The C API received support for creating custom ORCv2 MaterializationUnits and APIs to retrieve an LLJIT instance’s linking layers. An ABI breaking change for LLVMOrcAbsoluteSymbols was introduced to make it consistent with LLVMOrcCreateCustomMaterializationUnit. (rGc8fc5e3ba942057d6c4cdcd1faeae69a28e7b671)

  • The C API received support for adding ORCv2 object buffers directly to an object layer. (rG7b73cd684a8d5fb44d34064200f10e2723085c33)

  • A breaking change to LLVMGetInlineAsm was introduced, adding a ninth argument LLVMBool CanThrow (D95745)

  • The C API received support for calling into the new pass manager. (D102136)

  • The C API function LLVMIntrinsicCopyOverloadedName has been deprecated. Please migrate to LLVMIntrinsicCopyOverloadedName2 which takes an extra module argument and which also handles unnamed types. (D99173)

  • The C API received support for dumping objects from ORCv2 (rGcec8e69f01c3374cb38c6683058381b96fab8f89)

  • A breaking change to LLVMOrcObjectTransformLayerTransformFunction was introduced, changing the order of the function pointer’s arguments. (rG8962c68ad007a525f9daa987c99eda57e0d0069a)

  • The C API received support for accessing utilities from the LLJIT IRTransformLayer and ThreadSafeModule classes. (D103855)

  • The C API received support for creating lazy-export MaterializationUnits (D104672)

  • The C API function LLVMPassBuilderOptionsSetCoroutines was removed because couroutine passes have been enabled by default. (D105877)

  • comdat noduplicates was renamed to comdat nodeduplicate and as a result, LLVMNoDuplicatesComdatSelectionKind was renamed to LLVMNoDeduplicateComdatSelectionKind. (D106319)

Changes to the FastISel infrastructure

  • FastISel no longer tracks killed registers, and instead leaves this to the register allocator. This means that hasTrivialKill() is removed, as well as the OpNIsKill parameters to the fastEmit_*() family of functions.

Changes to the Debug Info

During this release …

Changes to the LLVM tools

  • The options --build-id-link-{dir,input,output} have been deleted. (D96310)

  • Support for in-order processors has been added to llvm-mca. (D94928)

  • llvm-objdump supports -M {att,intel} now. --x86-asm-syntax is a deprecated internal option which will be removed in LLVM 14.0.0. (D101695)

  • The llvm-readobj short aliases -s (previously --sections) and -t (previously --syms) have been changed to --syms and --section-details respectively, to match llvm-readelf. (D105055)

  • The llvm-nm short aliases -M (--print-armap), -U (--defined-only), and -W (--no-weak) are now deprecated. Use the long form versions instead. The alias --just-symbol-name is now deprecated in favor of --format=just-symbols and -j. (D105330)

  • In lli the default JIT engine switched from MCJIT (-jit-kind=mcjit) to ORC (-jit-kind=orc). (D98931)

  • llvm-rc got support for invoking Clang to preprocess its input. (D100755)

  • llvm-rc got a GNU windres compatible frontend, llvm-windres. (D100756)

  • llvm-ml has improved compatibility with MS ml.exe, managing to assemble more asm files.

Changes to LLDB

  • LLDB executable is now included in pre-built LLVM binaries.

  • LLDB now includes full featured support for AArch64 SVE register access.

  • LLDB now supports AArch64 Pointer Authentication, allowing stack unwind with signed return address.

  • LLDB now supports debugging programs on AArch64 Linux that use memory tagging (MTE).

  • Added memory tag read and memory tag write commands.

  • The memory region command will note when a region has memory tagging enabled.

  • Synchronous and asynchronous tag faults are recognised.

  • Synchronous tag faults have memory tag annotations in addition to the usual fault address.

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.