https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117699
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Hmm, reading https://gcc.gnu.org/onlinedocs/gccint/define_005fpeephole2.html#index-define_005fpeephole2 gives an impression if the scratch register is needed not to conflicting with the output then a match_dup is needed too. ``` Scratch registers are requested with a match_scratch pattern at the top level of the input pattern. The allocated register (initially) will be dead at the point requested within the original sequence. If the scratch is used at more than a single point, a match_dup pattern at the top level of the input pattern marks the last position in the input sequence at which the register must be available. ``` Ths is this would correct: ``` (define_peephole2 [(match_scratch:QI 3 "d") (parallel [(set (match_operand:ALL4 0 "register_operand" "") (ashift:ALL4 (match_operand:ALL4 1 "register_operand" "") (match_operand:QI 2 "const_int_operand" ""))) (clobber (reg:CC REG_CC))]) (match_dup 3)] ``` That is it must not conflict with the output register too. Now I could be reading this incorrectly and it should conflict with the output register without the extra match_dup there.
