https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68291
--- Comment #7 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- Eric, apologies for the slow response, I'm in the middle of an all-week trip with little Internet access. I think the best course of action is to adjust gimple_can_coalesce_p so that it returns false for RESULT_DECLs for which promote_ssa_mode returns BLKmode, and then adjust the block you quoted to assign a group rtx to the result decl, like the original code (still present a few lines below) used to do when hard_function_value returned a non-REG. I don't think we can allow coalescing in this case, because IIRC expanders can't deal with these parallels in general. I can look into this next week, when I'll be back home, if you prefer. Just let me know.
