lld 19.1.7 Release Notes — lld 19.1.7 documentation

# lld 19.1.7 Release Notes

## Introduction

This document contains the release notes for the lld linker, release 19.1.7. 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

- Experimental CREL relocations with explicit addends are now supported using the temporary section type code 0x40000020 (`clang -c -Wa,--crel,--allow-experimental-crel`). LLVM will change the code and break compatibility (Clang and lld of different versions are not guaranteed to cooperate, unlike other features). CREL with implicit addends are not supported. (#98115)

- `EI_OSABI` in the output is now inferred from input object files. (#97144)

- `--compress-sections <section-glib>={none,zlib,zstd}[:level]` is added to compress matched output sections without the `SHF_ALLOC` flag. (#84855) (#90567)

- The default compression level for zlib is now independent of linker optimization level (`Z_BEST_SPEED`).

- zstd compression parallelism no longer requires `ZSTD_MULITHREAD` build.

- `GNU_PROPERTY_AARCH64_FEATURE_PAUTH` notes, `R_AARCH64_AUTH_ABS64` and `R_AARCH64_AUTH_RELATIVE` relocations are now supported. (#72714)

- `--no-allow-shlib-undefined` now rejects non-exported definitions in the `def-hidden.so ref.so` case. (#86777)

- `--debug-names` is added to create a merged `.debug_names` index from input `.debug_names` sections. Type units are not handled yet. (#86508)

- `--enable-non-contiguous-regions` option allows automatically packing input sections into memory regions by automatically spilling to later matches if a region would overflow. This reduces the toil of manually packing regions (typical for embedded). It also makes full LTO feasible in such cases, since IR merging currently prevents the linker script from referring to input files. (#90007)

- `--default-script`/`-dT`` is implemented to specify a default script that is processed if `--script`/`-T` is not specified. (#89327)

- `--force-group-allocation` is implemented to discard `SHT_GROUP` sections and combine relocation sections if their relocated section group members are placed to the same output section. (#94704)

- `--build-id` now defaults to generating a 20-byte digest (“sha1”) instead of 8-byte (“fast”). This improves compatibility with RPM packaging tools. (#93943)

- `-z lrodata-after-bss` is implemented to place `.lrodata` after `.bss`. (#81224)

- `--export-dynamic` no longer creates dynamic sections for `-no-pie` static linking.

- `--lto-emit-asm` is now added as the canonical spelling of `--plugin-opt=emit-llvm`.

- `--lto-emit-llvm` now uses the pre-codegen module. (#97480)

- When AArch64 PAuth is enabled, `-z pack-relative-relocs` now encodes `R_AARCH64_AUTH_RELATIVE` relocations in `.rela.auth.dyn`. (#96496)

- `-z gcs` and `-z gcs-report` are now supported for AArch64 Guarded Control Stack extension.

- `-r` now forces `-Bstatic`.

- Thumb2 PLT is now supported for Cortex-M processors. (#93644)

- `DW_EH_sdata4` of addresses larger than 0x80000000 is now supported for MIPS32. (#92438)

- Certain unknown section types are rejected. (#85173)

- `PROVIDE(lhs = rhs) PROVIDE(rhs = ...)`, `lhs` is now defined only if `rhs` is needed. (#74771) (#87530)

- `OUTPUT_FORMAT(binary)` is now supported. (#98837)

- `NOCROSSREFS` and `NOCRFOSSREFS_TO` commands now supported to prohibit cross references between certain output sections. (#98773)

- Orphan placement is refined to prefer the last similar section when its rank <= orphan’s rank. (#94099) Non-alloc orphan sections are now placed at the end. (#94519)

- `R_X86_64_REX_GOTPCRELX` of the addq form is no longer incorrectly optimized when the address is larger than 0x80000000.

### Breaking changes

### COFF Improvements

### MinGW Improvements

### MachO Improvements

- Chained fixups are now enabled by default when targeting macOS 13.0, iOS 13.4, tvOS 14.0, watchOS 7.0, and visionOS 1.0 or later. They can be disabled with the -no_fixup_chains flag. (#99255)

### WebAssembly Improvements

#### Fixes