1=========================== 2lld |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 |release| release. 12 Release notes for previous releases can be found on 13 `the Download Page <https://releases.llvm.org/download.html>`_. 14 15Introduction 16============ 17 18This document contains the release notes for the lld linker, release |release|. 19Here we describe the status of lld, including major improvements 20from the previous release. All lld releases may be downloaded 21from the `LLVM releases web site <https://llvm.org/releases/>`_. 22 23Non-comprehensive list of changes in this release 24================================================= 25 26ELF Improvements 27---------------- 28 29* When ``--threads=`` is not specified, the number of concurrency is now capped to 16. 30 A large ``--thread=`` can harm performance, especially with some system 31 malloc implementations like glibc's. 32 (`D147493 <https://reviews.llvm.org/D147493>`_) 33* ``--remap-inputs=`` and ``--remap-inputs-file=`` are added to remap input files. 34 (`D148859 <https://reviews.llvm.org/D148859>`_) 35* ``--lto=`` is now available to support ``clang -funified-lto`` 36 (`D123805 <https://reviews.llvm.org/D123805>`_) 37* ``--lto-CGO[0-3]`` is now available to control ``CodeGenOpt::Level`` independent of the LTO optimization level. 38 (`D141970 <https://reviews.llvm.org/D141970>`_) 39* ``--check-dynamic-relocations=`` is now correct 32-bit targets when the addend is larger than 0x80000000. 40 (`D149347 <https://reviews.llvm.org/D149347>`_) 41* ``--print-memory-usage`` has been implemented for memory regions. 42 (`D150644 <https://reviews.llvm.org/D150644>`_) 43* ``SHF_MERGE``, ``--icf=``, and ``--build-id=fast`` have switched to 64-bit xxh3. 44 (`D154813 <https://reviews.llvm.org/D154813>`_) 45* Quoted output section names can now be used in linker scripts. 46 (`#60496 <https://github.com/llvm/llvm-project/issues/60496>`_) 47* ``MEMORY`` can now be used without a ``SECTIONS`` command. 48 (`D145132 <https://reviews.llvm.org/D145132>`_) 49* ``REVERSE`` can now be used in input section descriptions to reverse the order of input sections. 50 (`D145381 <https://reviews.llvm.org/D145381>`_) 51* Program header assignment can now be used within ``OVERLAY``. This functionality was accidentally lost in 2020. 52 (`D150445 <https://reviews.llvm.org/D150445>`_) 53* Operators ``^`` and ``^=`` can now be used in linker scripts. 54* LoongArch is now supported. 55* ``DT_AARCH64_MEMTAG_*`` dynamic tags are now supported. 56 (`D143769 <https://reviews.llvm.org/D143769>`_) 57* AArch32 port now supports BE-8 and BE-32 modes for big-endian. 58 (`D140201 <https://reviews.llvm.org/D140201>`_) 59 (`D140202 <https://reviews.llvm.org/D140202>`_) 60 (`D150870 <https://reviews.llvm.org/D150870>`_) 61* ``R_ARM_THM_ALU_ABS_G*`` relocations are now supported. 62 (`D153407 <https://reviews.llvm.org/D153407>`_) 63* ``.ARM.exidx`` sections may start at non-zero output section offset. 64 (`D148033 <https://reviews.llvm.org/D148033>`_) 65* Arm Cortex-M Security Extensions is now implemented. 66 (`D139092 <https://reviews.llvm.org/D139092>`_) 67* BTI landing pads are now added to PLT entries accessed by range extension thunks or relative vtables. 68 (`D148704 <https://reviews.llvm.org/D148704>`_) 69 (`D153264 <https://reviews.llvm.org/D153264>`_) 70* AArch64 short range thunk has been implemented to mitigate the performance loss of a long range thunk. 71 (`D148701 <https://reviews.llvm.org/D148701>`_) 72* ``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. 73 (`D147100 <https://reviews.llvm.org/D147100>`_) 74 (`D147364 <https://reviews.llvm.org/D147364>`_) 75* ``--no-power10-stubs`` now works for PowerPC64. 76* ``DT_PPC64_OPT`` is now supported; 77 (`D150631 <https://reviews.llvm.org/D150631>`_) 78* ``PT_RISCV_ATTRIBUTES`` is added to include the SHT_RISCV_ATTRIBUTES section. 79 (`D152065 <https://reviews.llvm.org/D152065>`_) 80* ``R_RISCV_PLT32`` is added to support C++ relative vtables. 81 (`D143115 <https://reviews.llvm.org/D143115>`_) 82* RISC-V global pointer relaxation has been implemented. Specify ``--relax-gp`` to enable the linker relaxation. 83 (`D143673 <https://reviews.llvm.org/D143673>`_) 84* The symbol value of ``foo`` is correctly handled when ``--wrap=foo`` and RISC-V linker relaxation are used. 85 (`D151768 <https://reviews.llvm.org/D151768>`_) 86* x86-64 large data sections are now placed away from code sections to alleviate relocation overflow pressure. 87 (`D150510 <https://reviews.llvm.org/D150510>`_) 88 89Breaking changes 90---------------- 91 92COFF Improvements 93----------------- 94 95* lld-link can now find libraries with relative paths that are relative to 96 `/libpath`. Before it would only be able to find libraries relative to the 97 current directory. 98 I.e. ``lld-link /libpath:c:\relative\root relative\path\my.lib`` where before 99 we would have to do ``lld-link /libpath:c:\relative\root\relative\path my.lib`` 100* lld-link learned -print-search-paths that will print all the paths where it will 101 search for libraries. 102* By default lld-link will now search for libraries in the toolchain directories. 103 Specifically it will search: 104 ``<toolchain>/lib``, ``<toolchain>/lib/clang/<version>/lib`` and 105 ``<toolchain>/lib/clang/<version>/lib/windows``. 106 107MinGW Improvements 108------------------ 109 110* A warning is now printed if the linked module contains runtime pseudo 111 relocations that are too narrow, that can end up producing runtime 112 errors if loaded too far away from the referenced DLL in the address 113 space. (`D154777 <https://reviews.llvm.org/D154777>`_) 114 115MachO Improvements 116------------------ 117 118WebAssembly Improvements 119------------------------ 120 121Fixes 122##### 123 124* Arm exception index tables (.ARM.exidx sections) are now output 125 correctly when they are at a non zero offset within their output 126 section. (`D148033 <https://reviews.llvm.org/D148033>`_) 127