http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57583
--- Comment #3 from Mikael Pettersson <mikpe at it dot uu.se> --- It's not too difficult to make the m68k backend use 32-bit offsets in its jump tables (adjust CASE_VECTOR_MODE, ASM_OUTPUT_ADDR_DIFF_ELT, ASM_RETURN_CASE_JUMP, drop the sign-extend from the tablejump expander, likewise in the unnamed insn that matches the output from the tablejump expander). I have a crude patch to do that, and make it compile-time selectable via an option. However, it seems to me that the compiler should be able to figure out for itself if a given jump table might need 32-bit offsets. In the worst case every element will overflow a (signed) 16-bit offset (0..32K-1 positive range) and need a GAS-inserted trampoline, for a total of 2 + 6 == 8 bytes per element. So tables with no more than 4K elements should work with 16-bit offsets. Tables larger than that may have their trampolines more than 32K away from the table PC base, which cannot work with 16-bit offsets, so for those the compiler should use 32-bit offsets. Seems to require implementing "casesi" for m68k though.
