defining add in a new port

[Jean-Marc Saffroy]

Hi gcc gurus,

I'm trying to port GCC to a new architecture, I'm new to gcc, and have
little problems defining add correctly.

My target has 2 types of (DI mode) registers, so I defined 2 classes:

- class D (data) regs can be used for computations, and that includes
operations such as additions and increments:
    reg  += small immediate
 or reg1 += reg2

- class A (address) can be used as base for loads, also they can be
modified with moves (between A-regs and from/to D-regs, not from
immediates) and with increments:
    reg += large immediate

So first for adddi3 I have defined the following:

(define_constraint "I"
  "Signed 6-bit integer constant for binops."
  (and (match_code "const_int")
       (match_test "IN_RANGE (ival, -24, 32)")))

(define_register_constraint "A" "ADDR_REGS"
  "The address registers.")

(define_register_constraint "D" "DATA_REGS"
  "The general (data) registers.")

(define_predicate "reg_or_18bit_signed_operand"
  (if_then_else (match_code "const_int")
    (match_test "IN_RANGE (INTVAL (op), -(1 << 17), (1 << 17) - 1)")
    (match_operand 0 "register_operand")))

(define_insn "adddi3"
  [(set (match_operand:DI 0 "register_operand" "=D,D,A")
        (plus:DI
         (match_operand:DI 1 "register_operand" "%0,0,0")
         (match_operand:DI 2 "reg_or_18bit_signed_operand" "I,D,n")))]
  ""
  "@
   addi   %0, %2
   add    %0, %2
   adda   %0, %2")

But this doesn't work, I get:

error: insn does not satisfy its constraints:
(insn 1424 1423 141 (set (reg:DI 2 r2)
        (plus:DI (reg:DI 2 r2)
            (const_int 40 [0x28])))
/home/jmsaffroy/cygnus/src/newlib/libc/time/strptime.c:165 24 {adddi3}
     (expr_list:REG_EQUIV (plus:DI (reg/f:DI 70 a6)
            (const_int 40 [0x28]))
        (nil)))

(r2 is a D-reg, a6 is an A-reg.)

It seems I was expecting too much intelligence from reload, or I didn't
give enough hints.

So I tried separating the add instructions for A-regs and D-regs into
different patterns with more restrictive predicates for each pattern (so
add for A regs can have large increments), but then I get other ICEs
which I don't understand (first assert in elimination_costs_in_insn fails).

Does anyone have a hint how I should approach this? Is a define_expand
required, or something else?


Cheers,
Jean-Marc