https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
Xi Ruoyao <xry111 at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever confirmed|0 |1 Last reconfirmed| |2023-09-08 --- Comment #5 from Xi Ruoyao <xry111 at gcc dot gnu.org> --- (In reply to chenglulu from comment #3) > This involves the template <optab>di3_fake: > (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"))))] > "" > { > return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands); > } > [(set_attr "type" "idiv") > (set_attr "mode" "SI") > (set (attr "enabled") > (if_then_else > (match_test "!!which_alternative == loongarch_check_zero_div_p()") > (const_string "yes") > (const_string "no")))]) > > > I think there is a problem with the implementation of this template. > First, the instructions generated in the template are [u]div.w[u], etc. The > description of such instructions in the instruction manual is that if the > upper 32 bits are not extended by the 31st bit sign then the result is > uncertain. I think this reason alone makes the pattern looks very wrong. I'll take a look...