428a7c1b38
ICF previously operated only within a given OutputSection. We would merge all CFStrings first, then merge all regular code sections in a second phase. This worked fine since CFStrings would never reference regular `__text` sections. However, I would like to expand ICF to merge functions that reference unwind info. Unwind info references the LSDA section, which can in turn reference the `__text` section, so we cannot perform ICF in phases. In order to have ICF operate on InputSections spanning multiple OutputSections, we need a way to distinguish InputSections that are destined for different OutputSections, so that we don't fold across section boundaries. We achieve this by creating OutputSections early, and setting `InputSection::parent` to point to them. This is what LLD-ELF does. (This change should also make it easier to implement the `section$start$` symbols.) This diff also folds InputSections w/o checking their flags, which I think is the right behavior -- if they are destined for the same OutputSection, they will have the same flags in the output (even if their input flags differ). I.e. the `parent` pointer check subsumes the `flags` check. In practice this has nearly no effect (ICF did not become any more effective on chromium_framework). I've also updated ICF.cpp's block comment to better reflect its current status. Reviewed By: #lld-macho, smeenai Differential Revision: https://reviews.llvm.org/D105641
7.9 KiB
7.9 KiB