9234066476
The processing of `-oso_prefix` uses `llvm::sys::fs::real_path` from the user value, but it is later tried to be matched with the result of `make_absolute`. While `real_path` resolves special symbols like `.`, `..` and `~`, and resolves symlinks along the path, `make_absolute` does neither, causing an incompatibility in some situations. In macOS, temporary directories would normally be reported as `/var/folders/<random>`, but `/var` is in fact a symlink to `private/var`. If own is working on a temporary directory and uses `-oso_prefix .`, it will be expanded to `/private/var/folder/<random>`, while `make_absolute` will expand to `/var/folder/<random>` instead, and `-oso_prefix` will fail to remove the prefix from the `N_OSO` entries, leaving absolute paths to the temporary directory in the resulting file. This would happen in any situation in which the working directory includes a symlink, not only in temporary directories. One can change the usage of `make_absolute` to use `real_path` as well, but `real_path` will mean checking the file system for each `N_OSO` entry. The other solution is stop using `real_path` when processing `-oso_prefix` and manually expand an input of `.` like `make_absolute` will do. This second option is the one implemented here, since it is the closest to the visible behaviour of ld64 (like the removed comment notes), so it is the better one for compatibility. This means that a test that checked the usage of the tilde as `-oso_prefix` needs to be removed (since it was done by using `real_path`), and two new tests are provided checking that symlinks do not affect the result. The second test checks a change in behaviour, in which if one provides the input files with a prefix of `./`, even when using `-oso_prefix .` because the matching is textual, the `./` prefix will stay in the `N_OSO` entries. This matches the observed behaviour of ld64.
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.