Re: /stable/12 future
- In reply to: Dimitry Andric : "Re: /stable/12 future"
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Tue, 21 Dec 2021 19:57:27 UTC
On Mon, 20 Dec 2021 at 15:54, Dimitry Andric <firstname.lastname@example.org> wrote: > > The obvious solution would seem to be to switch to lld as the default > linker, however that also runs into a snag. Since lld uses the blx > instruction for interworking, it prints a warning "lld uses blx > instruction, no object with architecture supporting feature detected". > > And because we link with the --fatal-warnings option, this stops> buildworld dead in its tracks. Obviously, this warning could be ignored > (by removing --fatal-warnings, or patching it out), but I think this > might result in issues when the actual binaries are run. I believe this warning is emitted in any environment that a blx instruction might be necessary, not that the instruction is actually used. From ELF/InputFiles.cpp: // The ARM support in lld makes some use of instructions that are not available // on all ARM architectures. Namely: // - Use of BLX instruction for interworking between ARM and Thumb state. // - Use of the extended Thumb branch encoding in relocation. // - Use of the MOVT/MOVW instructions in Thumb Thunks. I wonder if we could remove the warning from ELF/Driver.cpp in the case that config->armHasBlx == false, and replace it with an error in ELF/Arch/ARM.cpp if we actually need to emit a blx instruction?