Hi Diego,
1. According to the insn rtx of error message,
I think you can check the design of "*move_reg" pattern.
You probably missed some constraints.
2. Since there is no 'mul' instruction on your target,
perhaps you can try not to provide any multiply naming patterns.
GCC will generate library call for you.
See Chapter 4 of GCC Internals for more information. :)
Best regards,
jasonwucj
2013/2/8 Diego Bernini <diego.bernini@xxxxxxxxx>:
> Hi to all,
> I am porting GCC to a custom architecture.
>
> The custom architecture has not a "mul" instruction. Hence I am
> working to generate a proper routine call. The external routine ("
> __mulqi3") expect to have the first parameter inside the reg #0, the
> second parameter inside the reg #1 and then it puts the result inside
> the reg #0.
>
> Starting from the porting for AVR, I tried to add the following
> machine description definitions:
>
> define_expand "mulqi3"
> [(set (match_operand:QI 0 "register_operand" "")
> (mult:QI (match_operand:QI 1 "register_operand" "")
> (match_operand:QI 2 "register_operand" "")))]
> ""
> "
> emit_insn (gen_mulqi3_call (operands[0], operands[1], operands[2]));
> DONE;
> ")
>
> (define_expand "mulqi3_call"
> [(set (reg:QI 0) (match_operand:QI 1 "register_operand" ""))
> (set (reg:QI 1) (match_operand:QI 2 "register_operand" ""))
> (parallel [(set (reg:QI 0) (mult:QI (reg:QI 0) (reg:QI 1)))
> (clobber (reg:QI 1))
> ])
> (set (match_operand:QI 0 "register_operand" "") (reg:QI 0))]
> ""
> "")
>
> (define_insn "*mulqi3_call"
> [(set (reg:QI 0) (mult:QI (reg:QI 0) (reg:QI 1)))
> (clobber (reg:QI 1))
> ]
> ""
> "call __mulqi3"
> )
>
> There is something wrong with these definitions, because trying to
> compile a simple multiplication I obtain
>
> error: insn does not satisfy its constraints:
> (insn 51 25 26 (set (reg:QI 0 A0 [orig:51 a ] [51])
> (reg:QI 2 A2)) 5 {*move_regs} (nil)
> (nil))
>
>
> Any advice?
>
> Best,
> Diego
