History

Fangrui Song d45df09435 [ELF] Place SHT_NOTE sections with the same alignment into one PT_NOTE Summary: While the generic ABI requires notes to be 8-byte aligned in ELF64, many vendor-specific notes (from Linux, NetBSD, Solaris, etc) use 4-byte alignment. In a PT_NOTE segment, if 4-byte aligned notes are followed by an 8-byte aligned note, the possible 4-byte padding may make consumers fail to parse the 8-byte aligned note. See PR41000 for a recent report about .note.gnu.property (NT_GNU_PROPERTY_TYPE_0). (Note, for NT_GNU_PROPERTY_TYPE_0, the consumers should probably migrate to PT_GNU_PROPERTY, but the alignment issue affects other notes as well.) To fix the issue, don't mix notes with different alignments in one PT_NOTE. If compilers emit 4-byte aligned notes before 8-byte aligned notes, we'll create at most 2 segments. sh_size%sh_addralign=0 is actually implied by the rule for linking unrecognized sections (in generic ABI), so we don't have to check that. Notes that match in name, type and attribute flags are concatenated into a single output section. The compilers have to ensure sh_size%sh_addralign=0 to make concatenated notes parsable. An alternative approach is to create a PT_NOTE for each SHT_NOTE, but we'll have to incur the sizeof(Elf64_Phdr)=56 overhead every time a new note section is introduced. Reviewers: ruiu, jakehehrlich, phosek, jhenderson, pcc, espindola Subscribers: emaste, arichardson, krytarowski, fedor.sergeev, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D61296 llvm-svn: 359853		2019-05-03 00:35:49 +00:00
..
COFF	lld-link: Add /force:multipleres extension to make dupe resource diag non-fatal	2019-05-02 21:21:55 +00:00
Common	Fail early if an output file is not writable	2019-03-11 16:30:55 +00:00
ELF	[ELF] Place SHT_NOTE sections with the same alignment into one PT_NOTE	2019-05-03 00:35:49 +00:00
MinGW	[MinGW] Add an --appcontainer flag, passed through to lld-link	2019-04-19 13:50:43 +00:00
cmake/modules	[CMake] Properly conditionalize installation of lld libraries	2018-03-09 13:09:36 +00:00
docs	lld-link: Add /force:multipleres extension to make dupe resource diag non-fatal	2019-05-02 21:21:55 +00:00
include/lld	Fail early if an output file is not writable	2019-03-11 16:30:55 +00:00
lib	Use llvm::stable_sort	2019-04-23 02:42:06 +00:00
test	[ELF] Place SHT_NOTE sections with the same alignment into one PT_NOTE	2019-05-03 00:35:49 +00:00
tools/lld	Update the file headers across all of the LLVM projects in the monorepo	2019-01-19 08:50:56 +00:00
unittests	Update the file headers across all of the LLVM projects in the monorepo	2019-01-19 08:50:56 +00:00
utils	Python 2/3 compatibility	2019-03-20 07:42:13 +00:00
wasm	[WebAssembly] Always take into account added when applying runtime relocations	2019-04-25 17:11:54 +00:00
.arcconfig	[lld] Set up .arcconfig to point to new Diffusion LLD repository	2017-12-06 20:56:23 +00:00
.clang-format	…
.gitignore	…
CMakeLists.txt	[WebAssembly] Initial wasm linker implementation	2017-11-17 18:14:09 +00:00
CODE_OWNERS.TXT	[WebAssembly] Initial wasm linker implementation	2017-11-17 18:14:09 +00:00
LICENSE.TXT	Fix typos throughout the license files that somehow I and my reviewers	2019-01-21 09:52:34 +00:00
README.md	Note that the test .tar.xz has been updated.	2017-12-22 19:37:32 +00:00

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.