https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115881
--- Comment #5 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Richard Sandiford from comment #4) > As expected, the results weren't pretty. Things like: > > (define_split > [(set (match_operand:SWI48 0 "register_operand") > (and:SWI48 (match_dup 0) > (const_int -65536))) > (clobber (reg:CC FLAGS_REG))] > "(TARGET_FAST_PREFIX && !TARGET_PARTIAL_REG_STALL) > || optimize_function_for_size_p (cfun)" > [(set (strict_low_part (match_dup 1)) (const_int 0))] > "operands[1] = gen_lowpart (HImode, operands[0]);") > > expect to be able to generate (strict_low_part (subreg:HI (reg:DI SP) 0)) > after reload, so we can't ban it outright. The fallback was going to be > to make register_operand reject subregs after reload, but patterns like: > > (define_insn_and_split "*neg<mode>_1_slp" > [(set (strict_low_part (match_operand:SWI12 0 "register_operand" > "+<r>,&<r>")\ > ) > (neg:SWI12 (match_operand:SWI12 1 "register_operand" "0,!<r>"))) > (clobber (reg:CC FLAGS_REG))] > > use register_operand for cases like the above. Not really sure what > to do here. Maybe define "register_operand_slp" predicate that would allow SUBREGs after reload? When accessing the operand of "register_operand_slp" after reload, one would have to use reg_or_subregno instead of REGNO.
