On 7/7/19 11:02 AM, William Tambe wrote: > Let's consider the following code snippet that retrieve the address of a label: > > mylabel: > void* ptr = &&mylabel; > > when compiling the above, GCC associate the label with the constraint "i". > > However, I am unable to force GCC to associate symbols with the > constraint "A" that I am defining in the excerpt below: > > ---------------------------------------- > (define_constraint "A" > "A memory address." > (and (match_code "mem") > (ior (match_test "GET_CODE (XEXP (op, 0)) == SYMBOL_REF") > (match_test "GET_CODE (XEXP (op, 0)) == LABEL_REF") > (match_test "GET_CODE (XEXP (op, 0)) == CONST")))) > > (define_insn "movsi" > [(set (match_operand:SI 0 "nonimmediate_operand" "=r,r") > (match_operand:SI 1 "general_operand" "A,i"))] > "" > "@ > gip %0, %1 > li %0, %1") > ---------------------------------------------------------- > > GCC always choose to match the line "li %0, %1" instead of the line > "gip %0, %1". > > How can I force GCC to match "gip %0, %1" for a symbol ? > You'd have to debug the register allocation and reloading phase to determine what it's doing and why. And, in general, you want your constraints and predicates to match as closely as possible. So in the above case your predicates are "nonimmediate_operand and "general_operand". You'd be better off with "register_operand" and "immediate_operand" since operand 0's constraints only allow registers and operand 1's constraints only allow immediates. Jeff
