llvm-project

20ca85b6 - [lld] macho: Support section branch relocations, including the 1-byte form (#169062)

[lld] macho: Support section branch relocations, including the 1-byte form (#169062) I noticed that we had a hardcoded value of 4 for the pcrel section relocations, which seems like an issue given that we recently added support for 1-byte branch relocations in https://github.com/llvm/llvm-project/pull/164439. The code included an assert that the relevant relocation had the BYTE4 attribute, but that is actually not enough to use a hardcoded value of 4: we need to assert that the *other* `BYTE<n>` attributes are not set either. However, since we did not support local branch relocations, that doesn't seem to have mattered in practice. That said, local branch relocations can be emitted by compilers, and ld64 does handle the 4-byte version of them, so I've added support for it here. ld64 actually seems to reject 1-byte section relocations, so the questionable code is actually probably fine (minus the incorrect assert). So we have two options: add an equivalent check in LLD, or just support 1-byte local branch relocations. Supporting it actually requires less code, so I've gone with that option here.