lld 20.1.0 Release Notes

Introduction

This document contains the release notes for the lld linker, release 20.1.0. Here we describe the status of lld, including major improvements from the previous release. All lld releases may be downloaded from the LLVM releases web site.

Non-comprehensive list of changes in this release

ELF Improvements

  • -z nosectionheader has been implemented to omit the section header table. The operation is similar to llvm-objcopy --strip-sections. (#101286)

  • --randomize-section-padding=<seed> is introduced to insert random padding between input sections and at the start of each segment. This can be used to control measurement bias in A/B experiments. (#117653)

  • The reproduce tarball created with --reproduce= now excludes directories specified in the --dependency-file argument (used by Ninja). This resolves an error where non-existent directories could cause issues when invoking ld.lld @response.txt.

  • --symbol-ordering-file= and call graph profile can now be used together.

  • When --call-graph-ordering-file= is specified, .llvm.call-graph-profile sections in relocatable files are no longer used.

  • --lto-basic-block-sections=labels is deprecated in favor of --lto-basic-block-address-map. (#110697)

  • In non-relocatable links, a .note.GNU-stack section with the SHF_EXECINSTR flag is now rejected unless -z execstack is specified. (#124068)

  • In relocatable links, the sh_entsize member of a SHF_MERGE section with relocations is now respected in the output.

  • Quoted names can now be used in output section phdr, memory region names, OVERLAY, the LHS of --defsym, and INSERT AFTER.

  • Section CLASS linker script syntax binds input sections to named classes, which are referenced later one or more times. This provides access to the automatic spilling mechanism of –enable-non-contiguous-regions without globally changing the semantics of section matching. It also independently increases the expressive power of linker scripts. (#95323)

  • INCLUDE cycle detection has been fixed. A linker script can now be included twice.

  • The archivename: syntax when matching input sections is now supported. (#119293)

  • To support Arm v6-M, short thunks using B.w are no longer generated. (#118111)

  • For AArch64, BTI-aware long branch thunks can now be created to a destination function without a BTI instruction. (#108989) (#116402)

  • Relocations related to GOT and TLSDESC for the AArch64 Pointer Authentication ABI are now supported.

  • Supported relocation types for x86-64 target: * R_X86_64_CODE_4_GOTPCRELX (#109783) (#116737) * R_X86_64_CODE_4_GOTTPOFF (#116634) * R_X86_64_CODE_4_GOTPC32_TLSDESC (#116909) * R_X86_64_CODE_6_GOTTPOFF (#117675)

  • Supported relocation types for LoongArch target: R_LARCH_TLS_{LD,GD,DESC}_PCREL20_S2. (#100105)

Breaking changes

  • Removed support for the (deprecated) R_RISCV_RVC_LUI relocation. This was a binutils-internal relocation used during relaxation, and was not emitted by compilers/assemblers.

COFF Improvements

  • /includeglob has been implemented to match the behavior of --undefined-glob available for ELF.

  • /lldsavetemps allows saving select intermediate LTO compilation results (e.g. resolution, preopt, promote, internalize, import, opt, precodegen, prelink, combinedindex).

  • /machine:arm64ec support completed, enabling the linking of ARM64EC images.

  • COFF weak anti-dependency alias symbols are now supported.

MinGW Improvements

  • --undefined-glob is now supported by translating into the /includeglob flag.

MachO Improvements

WebAssembly Improvements

Fixes