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4bbcd63eea
For one metadata section usage, each text section references a metadata section. The metadata sections have a C identifier name to allow the runtime to collect them via `__start_/__stop_` symbols. Since `__start_`/`__stop_` references are always present from live sections, the C identifier name sections appear like GC roots, which means they cannot be discarded by `ld --gc-sections`. To make such sections GCable, either SHF_LINK_ORDER or a section group is needed. SHF_LINK_ORDER is not suitable for the references can be inlined into other functions (See D97430: Function A (in the section .text.A) references its `__sancov_guard` section. Function B inlines A (so now .text.B references `__sancov_guard` - this is invalid with the semantics of SHF_LINK_ORDER). In the linking stage, if `.text.A` gets discarded, and `__sancov_guard` is retained via the reference from `.text.B`, the output will be invalid because `__sancov_guard` references the discarded `.text.A`. LLD errors "sh_link points to discarded section". ) A section group have size overhead, and is cumbersome when there is just one metadata section. Add `-z start-stop-gc` to drop the "__start_/__stop_ references retain non-SHF_LINK_ORDER non-SHF_GROUP C identifier name sections" rule. We reserve the rights to switch the default in the future. Reviewed By: phosek, jrtc27 Differential Revision: https://reviews.llvm.org/D96914 |
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| .. | ||
| cmake/modules | ||
| COFF | ||
| Common | ||
| docs | ||
| ELF | ||
| include/lld | ||
| lib | ||
| MachO | ||
| MinGW | ||
| test | ||
| tools/lld | ||
| unittests | ||
| utils | ||
| wasm | ||
| .clang-format | ||
| .clang-tidy | ||
| .gitignore | ||
| CMakeLists.txt | ||
| CODE_OWNERS.TXT | ||
| LICENSE.TXT | ||
| README.md | ||
LLVM Linker (lld)
This directory and its subdirectories contain source code for the LLVM Linker, a modular cross platform linker which is built as part of the LLVM compiler infrastructure project.
lld is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.
Benchmarking
In order to make sure various developers can evaluate patches over the same tests, we create a collection of self contained programs.
It is hosted at https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz
The current sha256 is 10eec685463d5a8bbf08d77f4ca96282161d396c65bd97dc99dbde644a31610f.