https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
--- Comment #15 from Xi Ruoyao <xry111 at gcc dot gnu.org> --- (In reply to chenglulu from comment #13) > (In reply to Xi Ruoyao from comment #12) > > (In reply to chenglulu from comment #11) > > > (In reply to Xi Ruoyao from comment #10) > > > > (In reply to Xi Ruoyao from comment #9) > > > > > > > > > (define_insn "<optab>di3_fake" > > > > > [(set (match_operand:DI 0 "register_operand" "=r,&r,&r") > > > > > - (sign_extend:DI > > > > > - (any_div:SI (match_operand:DI 1 "register_operand" "r,r,0") > > > > > - (match_operand:DI 2 "register_operand" > > > > > "r,r,r"))))] > > > > > - "" > > > > > + (if_then_else > > > > > + (and (eq (match_operand:DI 1 "register_operand" "r,r,0") > > > > > + (sign_extend:DI (subreg:SI (match_dup 1) 0))) > > > > > + (eq (match_operand:DI 2 "register_operand" "r,r,r") > > > > > + (sign_extend:DI (subreg:SI (match_dup 2) 0)))) > > > > > + (sign_extend:DI > > > > > + (any_div:SI (subreg:SI (match_dup 1) 0) > > > > > + (subreg:SI (match_dup 2) 0))) > > > > > + (unspec:DI [(const_int 0)] UNSPEC_BAD_DIVW)))] > > > > > > > > With this the compiler will still believe all bad {div,mod}.w{,u} > > > > > > I think this is already defined as UNSPEC. Isn’t the simpler the logic, > > > the > > > better? > > > > Yes, I think we should just use 4 different UNSPEC_ values and the simple > > version. But I've not find a way to use 4 different UNSPEC_ values in the > > RTL template except duplicating everything 4 times... > > I still have a question that I don't quite understand, that is, why that the > four generated strings are equivalent when using an UNSPEC name? My template > names are different, and they will not be automatically matched during > optimization.??? Oh I get it, you mean (define_insn "<optab>di3_fake" [(set (match_operand:DI 0 "register_operand" "=r,&r,&r") (sign_extend:DI - (any_div:SI (match_operand:DI 1 "register_operand" "r,r,0") - (match_operand:DI 2 "register_operand" "r,r,r"))))] + (unspec:DI [(any_div:DI + (match_operand:DI 1 "register_operand" "r,r,0") + (match_operand:DI 2 "register_operand" "r,r,r"))] + UNSPEC_ANY_DIV)))] "" { return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands); Good idea! I think it's better than my stupid hacks :). I'd been thinking about: (define_insn "<optab>di3_fake" [(set (match_operand:DI 0 "register_operand" "=r,&r,&r") (sign_extend:DI - (any_div:SI (match_operand:DI 1 "register_operand" "r,r,0") - (match_operand:DI 2 "register_operand" "r,r,r"))))] + (unspec:DI [(match_operand:DI 1 "register_operand" "r,r,0") + (match_operand:DI 2 "register_operand" "r,r,r")] + UNSPEC_ANY_DIV)))] "" { return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands); and this is just wrong.