https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112669
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Thomas Schwinge <tschwi...@gcc.gnu.org>: https://gcc.gnu.org/g:297fe5c166f1d920da6d5ef9c7e02846b0148575 commit r14-5884-g297fe5c166f1d920da6d5ef9c7e02846b0148575 Author: Thomas Schwinge <tho...@codesourcery.com> Date: Wed Nov 22 17:35:23 2023 +0100 GCN: Tag '-march=[...]', '-mtune=[...]' as 'Negative' of themselves [PR112669] Certain other command-line flags are mutually exclusive (random example: GCN '-march=gfx906', '-march=gfx908'). If they're not appropriately marked up, this does disturb the multilib selection machinery, for example: $ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-multi-directory -march=gfx906 gfx906 $ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-multi-directory -march=gfx908 gfx908 $ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-multi-directory -march=gfx906 -march=gfx908 . In the last invocation, '-march=gfx900 -march=gfx906', for example, in 'gcc/gcc.cc:set_multilib_dir' we see both flags -- which there doesn't exist a matching multilib for, therefore we "fail" to the default ('.'). Tagges as 'Negative', only the last flag survives, and we, for example, get the expected: $ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-multi-directory -march=gfx906 -march=gfx908 gfx908 I quickly found that the same also applies to GCN's '-mtune=[...]', but I've not otherwise reviewed the GCN options. PR target/112669 gcc/ * config/gcn/gcn.opt (march=, mtune=): Tag as 'Negative' of themselves.
