https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91255
Bug ID: 91255 Summary: Can't use define_subst in target that uses set_attr_alternative Product: gcc Version: 9.0 Status: UNCONFIRMED Keywords: internal-improvement Severity: normal Priority: P3 Component: other Assignee: unassigned at gcc dot gnu.org Reporter: ktkachov at gcc dot gnu.org CC: rsandifo at gcc dot gnu.org Target Milestone: --- I'm trying to add a define_subst use in the arm backend but am getting many build errors complaining about: `set_attr_alternative' is unsupported by `define_subst' Looking at the gensupport.c code it iterates over all define_insns and errors if any of them have set_attr_alternative. The usecase I'm targetting doesn't involve patterns with set_attr_alternative, so could we make the define_subst handling more robust to only error out if the define_subst is actually attempted on a set_attr_alternative? grepping around the sources it looks like the only ports that make use of define_subst don't have any set_attr_alternative occurrences