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lld Release Notes

PreRelease

Warning

These are in-progress notes for the upcoming LLVM release. Release notes for previous releases can be found on the Download Page.

Introduction

This document contains the release notes for the lld linker, release . 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

  • When --threads= is not specified, the number of concurrency is now capped to 16. A large --thread= can harm performance, especially with some system malloc implementations like glibc's. (D147493)
  • --remap-inputs= and --remap-inputs-file= are added to remap input files. (D148859)
  • --lto= is now available to support clang -funified-lto (D123805)
  • --lto-CGO[0-3] is now available to control CodeGenOpt::Level independent of the LTO optimization level. (D141970)
  • --check-dynamic-relocations= is now correct 32-bit targets when the addend is larger than 0x80000000. (D149347)
  • --print-memory-usage has been implemented for memory regions. (D150644)
  • SHF_MERGE, --icf=, and --build-id=fast have switched to 64-bit xxh3. (D154813)
  • Quoted output section names can now be used in linker scripts. (#60496)
  • MEMORY can now be used without a SECTIONS command. (D145132)
  • REVERSE can now be used in input section descriptions to reverse the order of input sections. (D145381)
  • Program header assignment can now be used within OVERLAY. This functionality was accidentally lost in 2020. (D150445)
  • Operators ^ and ^= can now be used in linker scripts.
  • LoongArch is now supported.
  • DT_AARCH64_MEMTAG_* dynamic tags are now supported. (D143769)
  • AArch32 port now supports BE-8 and BE-32 modes for big-endian. (D140201) (D140202) (D150870)
  • R_ARM_THM_ALU_ABS_G* relocations are now supported. (D153407)
  • .ARM.exidx sections may start at non-zero output section offset. (D148033)
  • Arm Cortex-M Security Extensions is now implemented. (D139092)
  • BTI landing pads are now added to PLT entries accessed by range extension thunks or relative vtables. (D148704) (D153264)
  • AArch64 short range thunk has been implemented to mitigate the performance loss of a long range thunk. (D148701)
  • R_AVR_8_LO8/R_AVR_8_HI8/R_AVR_8_HLO8/R_AVR_LO8_LDI_GS/R_AVR_HI8_LDI_GS have been implemented. (D147100) (D147364)
  • --no-power10-stubs now works for PowerPC64.
  • DT_PPC64_OPT is now supported; (D150631)
  • PT_RISCV_ATTRIBUTES is added to include the SHT_RISCV_ATTRIBUTES section. (D152065)
  • R_RISCV_PLT32 is added to support C++ relative vtables. (D143115)
  • RISC-V global pointer relaxation has been implemented. Specify --relax-gp to enable the linker relaxation. (D143673)
  • The symbol value of foo is correctly handled when --wrap=foo and RISC-V linker relaxation are used. (D151768)
  • x86-64 large data sections are now placed away from code sections to alleviate relocation overflow pressure. (D150510)

Breaking changes

COFF Improvements

  • lld-link can now find libraries with relative paths that are relative to /libpath. Before it would only be able to find libraries relative to the current directory. I.e. lld-link /libpath:c:\relative\root relative\path\my.lib where before we would have to do lld-link /libpath:c:\relative\root\relative\path my.lib
  • lld-link learned -print-search-paths that will print all the paths where it will search for libraries.
  • By default lld-link will now search for libraries in the toolchain directories. Specifically it will search: <toolchain>/lib, <toolchain>/lib/clang/<version>/lib and <toolchain>/lib/clang/<version>/lib/windows.

MinGW Improvements

  • A warning is now printed if the linked module contains runtime pseudo relocations that are too narrow, that can end up producing runtime errors if loaded too far away from the referenced DLL in the address space. (D154777)

MachO Improvements

WebAssembly Improvements

Fixes

  • Arm exception index tables (.ARM.exidx sections) are now output correctly when they are at a non zero offset within their output section. (D148033)