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IOW what's the point of silently ignoring > > .addrsig_sym when there's no .addrsig anywhere? > > Because addrsig is an opt-in mechanism. A file with only .addrsig means that > none of the symbols are address significant, while a file without is treated > as if all symbols were. > > The silent ignore behavior is not ideal, but it could be added later. The > primary target of this patch is compiler generated output. The idea is that if no symbol is address significant, clang -S just emits `.addrsig` with no `.addrsig_sym $sym`. The .llvm_addrsig section is empty but it conveys information to ld.lld --icf=safe. In llvm-mc, `.addrsig_sym` accepts exactly one symbol. Technically, if the directive were designed to support zero or any number of symbols, `.addrsig` could be removed. > > And such a toggle-on > > directive likely would want to allow expressing also (or even only) > > via a command line option. > > How would that work? That leads to two kind of end results, 1. mark *all* > symbols as address-insignificant (if there's no addrsig_sym directives) > or maybe 2. toggle off llvm_addrsig support (but why?).