Thank you very much for your attention. Meena, could you please give me advice about how to set up eliminating FP against SP ? In my target.h, these macros are NOT defined : ELIMINABLE_REGS CAN_ELIMINATE INITIAL_ELIMINATION_OFFSET I changed target.md : ________________________________________ ;; movhi (define_expand "movhi" [(set (match_operand:HI 0 "nonimmediate_operand" "") (match_operand:HI 1 "general_operand" "") )] "" { /* First try */ /* if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) != REG) { operands[1] = force_reg (HImode, operands[1]); } */ /* Second try */ if (!register_operand(operand0, HImode) && !register_operand(operand1, HImode)) { operands[1] = copy_to_mode_reg(HImode, operand1); } } ) ;; move.w r -> (r) (define_insn "movhi1" [(set (match_operand:HI 0 "nonimmediate_operand" "=r,m,r,r") (match_operand:HI 1 "general_operand" "r,r,m,i") )] "" "@ move.w\t%1,%0 move.w\t%1,%0 move.w\t%1,%0 move.w\t%1,%0" ) ______________________________ First and second try (as commented in the code) are successful to force copying immediate into register and then register into memory. But then, with both of them, this error appears: e.c:7: error: unrecognizable insn: (insn 8 7 9 3 e.c:4 (set (mem/c/i:HI (reg/f:HI 14) [0 i+0 S2 A16]) (reg:HI 15)) -1 (nil)) I don't know why. Since the pattern movhi1 allows register to memory transfer. I still wonder how I can deal with access modes ? For example, to obtain such an ASM instruction ______________ movew r1,8(r2) ;; move R1 to [R2 + 8] ______________ How to do that ? How to check the access mode ? Where to catch the 8 (in the example) ? Regards. Florent