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* Experimental CREL relocations with explicit addends are now supported using the 30 temporary section type code 0x40000020 (``clang -c -Wa,--crel,--allow-experimental-crel``). 31 LLVM will change the code and break compatibility (Clang and lld of different 32 versions are not guaranteed to cooperate, unlike other features). CREL with 33 implicit addends are not supported. 34 (`#98115 <https://github.com/llvm/llvm-project/pull/98115>`_) 35* ``EI_OSABI`` in the output is now inferred from input object files. 36 (`#97144 <https://github.com/llvm/llvm-project/pull/97144>`_) 37* ``--compress-sections <section-glib>={none,zlib,zstd}[:level]`` is added to compress 38 matched output sections without the ``SHF_ALLOC`` flag. 39 (`#84855 <https://github.com/llvm/llvm-project/pull/84855>`_) 40 (`#90567 <https://github.com/llvm/llvm-project/pull/90567>`_) 41* The default compression level for zlib is now independent of linker 42 optimization level (``Z_BEST_SPEED``). 43* zstd compression parallelism no longer requires ``ZSTD_MULITHREAD`` build. 44* ``GNU_PROPERTY_AARCH64_FEATURE_PAUTH`` notes, ``R_AARCH64_AUTH_ABS64`` and 45 ``R_AARCH64_AUTH_RELATIVE`` relocations are now supported. 46 (`#72714 <https://github.com/llvm/llvm-project/pull/72714>`_) 47* ``--no-allow-shlib-undefined`` now rejects non-exported definitions in the 48 ``def-hidden.so ref.so`` case. 49 (`#86777 <https://github.com/llvm/llvm-project/issues/86777>`_) 50* ``--debug-names`` is added to create a merged ``.debug_names`` index 51 from input ``.debug_names`` sections. Type units are not handled yet. 52 (`#86508 <https://github.com/llvm/llvm-project/pull/86508>`_) 53* ``--enable-non-contiguous-regions`` option allows automatically packing input 54 sections into memory regions by automatically spilling to later matches if a 55 region would overflow. This reduces the toil of manually packing regions 56 (typical for embedded). It also makes full LTO feasible in such cases, since 57 IR merging currently prevents the linker script from referring to input 58 files. (`#90007 <https://github.com/llvm/llvm-project/pull/90007>`_) 59* ``--default-script`/``-dT`` is implemented to specify a default script that is processed 60 if ``--script``/``-T`` is not specified. 61 (`#89327 <https://github.com/llvm/llvm-project/pull/89327>`_) 62* ``--force-group-allocation`` is implemented to discard ``SHT_GROUP`` sections 63 and combine relocation sections if their relocated section group members are 64 placed to the same output section. 65 (`#94704 <https://github.com/llvm/llvm-project/pull/94704>`_) 66* ``--build-id`` now defaults to generating a 20-byte digest ("sha1") instead 67 of 8-byte ("fast"). This improves compatibility with RPM packaging tools. 68 (`#93943 <https://github.com/llvm/llvm-project/pull/93943>`_) 69* ``-z lrodata-after-bss`` is implemented to place ``.lrodata`` after ``.bss``. 70 (`#81224 <https://github.com/llvm/llvm-project/pull/81224>`_) 71* ``--export-dynamic`` no longer creates dynamic sections for ``-no-pie`` static linking. 72* ``--lto-emit-asm`` is now added as the canonical spelling of ``--plugin-opt=emit-llvm``. 73* ``--lto-emit-llvm`` now uses the pre-codegen module. 74 (`#97480 <https://github.com/llvm/llvm-project/pull/97480>`_) 75* When AArch64 PAuth is enabled, ``-z pack-relative-relocs`` now encodes ``R_AARCH64_AUTH_RELATIVE`` relocations in ``.rela.auth.dyn``. 76 (`#96496 <https://github.com/llvm/llvm-project/pull/96496>`_) 77* ``-z gcs`` and ``-z gcs-report`` are now supported for AArch64 Guarded Control Stack extension. 78* ``-r`` now forces ``-Bstatic``. 79* Thumb2 PLT is now supported for Cortex-M processors. 80 (`#93644 <https://github.com/llvm/llvm-project/pull/93644>`_) 81* ``DW_EH_sdata4`` of addresses larger than 0x80000000 is now supported for MIPS32. 82 (`#92438 <https://github.com/llvm/llvm-project/pull/92438>`_) 83* Certain unknown section types are rejected. 84 (`#85173 <https://github.com/llvm/llvm-project/pull/85173>`_) 85* ``PROVIDE(lhs = rhs) PROVIDE(rhs = ...)``, ``lhs`` is now defined only if ``rhs`` is needed. 86 (`#74771 <https://github.com/llvm/llvm-project/issues/74771>`_) 87 (`#87530 <https://github.com/llvm/llvm-project/pull/87530>`_) 88* ``OUTPUT_FORMAT(binary)`` is now supported. 89 (`#98837 <https://github.com/llvm/llvm-project/pull/98837>`_) 90* ``NOCROSSREFS`` and ``NOCRFOSSREFS_TO`` commands now supported to prohibit 91 cross references between certain output sections. 92 (`#98773 <https://github.com/llvm/llvm-project/pull/98773>`_) 93* Orphan placement is refined to prefer the last similar section when its rank <= orphan's rank. 94 (`#94099 <https://github.com/llvm/llvm-project/pull/94099>`_) 95 Non-alloc orphan sections are now placed at the end. 96 (`#94519 <https://github.com/llvm/llvm-project/pull/94519>`_) 97* ``R_X86_64_REX_GOTPCRELX`` of the addq form is no longer incorrectly optimized when the address is larger than 0x80000000. 98 99Breaking changes 100---------------- 101 102COFF Improvements 103----------------- 104 105MinGW Improvements 106------------------ 107 108MachO Improvements 109------------------ 110 111* Chained fixups are now enabled by default when targeting macOS 13.0, 112 iOS 13.4, tvOS 14.0, watchOS 7.0, and visionOS 1.0 or later. 113 They can be disabled with the `-no_fixup_chains` flag. 114 (`#99255 <https://github.com/llvm/llvm-project/pull/99255>`_) 115 116WebAssembly Improvements 117------------------------ 118 119Fixes 120##### 121