Re: Problem with modyfying "addsi3" in machine description

[Tomasz Jankowski <tomcioj at gmail dot com>]

Ok, I fixed it using using pair of define_insn and define_expand below:

   (define_expand "addsi3"
     [(set (match_operand:SI 0 "register_operand" "=r")
           (plus:SI (match_operand:SI 1 "register_operand" "r")
                    (match_operand:SI 2 "nonmemory_operand" "")))]
     ""
     {
       if (CONST_INT_P (operands [2]))
       {
         if (can_create_pseudo_p ())
         {
           operands[2] = force_reg (SImode, operands[2]);
           emit_insn (gen_rtx_SET (SImode, operands[0], gen_rtx_PLUS
(SImode, operands [1], operands [2])));
         }
       }
       else
       {
         emit_insn (gen_rtx_SET (SImode, operands[0], gen_rtx_PLUS
(SImode, operands [1], operands [2])));
       }
       DONE;
     })

   (define_insn "*addsi3_internal"
     [(set (match_operand:SI 0 "register_operand" "=r")
           (plus:SI (match_operand:SI 1 "register_operand" "r")
                    (match_operand:SI 2 "register_operand" "r")))]
     ""
     "l.radd   \t%0,%1,%2"
     [(set_attr "type" "add")
      (set_attr "length" "1")])

I have to admit, that I don't understand why it works... I figured out
possible explanation. When define_expand doesn't emit any insns, but
it finishes with DONE, GCC tries other strategy to fir RTL instruction
to machine description, right?

I have also question about output assembly (compiled with -dP option).
Sample C code:

    int b = 123;
    int a = b + 998;

output:

    #(insn 8 7 19 simple_test.c:4 (set (reg:SI 3 r3 [44])
    #        (const_int 998 [0x3e6])) 8 {*movsi_insn} (nil))
    	l.addi  	r3,r0,998	 # move immediate I	# 8	*movsi_insn/1	[length = 1]
    #(insn 19 8 9 (set (reg:SI 3 r3 [44])
    #        (rto:SI (reg:SI 3 r3 [44]))) 72 {rto} (nil))
    	l.rto    	r3,r3	# 19	rto	[length = 1]
    #(insn 9 19 10 simple_test.c:4 (set:SI (reg:SI 3 r3 [43])
    #        (plus:SI (reg:SI 4 r4 [42])
    #            (reg:SI 3 r3 [44]))) 49 {*addsi3_internal}
(expr_list:REG_EQUAL (plus:SI (reg:SI 4 r4 [42])
    #            (const_int 998 [0x3e6]))
    #        (nil)))
    	l.radd   	r3,r4,r3	# 9	*addsi3_internal	[length = 1]

What "(expr_list:REG_EQUAL (..." stays for?