Several newbie questions (+any simple .md available?)

[Sami Khawam <S dot Khawam at ee dot ed dot ac dot uk>]

Hi all,

I am sure these questions have been asked in the 
past, however I was unable to find any response in 
the archive. Any help would be appreciated.

Basically I am trying to port gcc to a custom cpu 
architecture. Does anyone know if there is a simple 
.md description of a cpu with the basic instruction 
set so I could start with it? I had a look at the 
'stormy16' and 'camille' descriptions which seem to 
be quite simple, however whenever I try to make any 
modifications I get a number of errors related to 
reloading etc.

Secondly, is there a way to output the internal RTL 
description of a compiled file?

Finally, one constraint I have in my CPU 
architecture is that constants (immediate operands) 
are not allowed in arithmetic instructions, thus 
operations like:
   ADD   r5, #5
have to become:
   MOV   r4, #5
   ADD   r5, r4

I tried to limit the insn definitions to fit this, 
but the compiler does not seem to be able to 
decompose the "ADD   r5, #5" instruction and 
complains that there is no insn of a plus with const:


Sections of the .md file:

(define_expand "movhi"
  [(set (match_operand 0 "register_operand" "")
	(match_operand 1 "general_operand" ""))]
  ""
  "")

(define_insn "*mov_all_modes" 

        [(set (match_operand 0 
"nonimmediate_nonstack_operand" "") 

              (match_operand 1 "general_operand" 
    ""))]
        "" 

        "MOV  %0, %1")

(define_expand "addhi3" 

        [(set (match_operand:HI 0 
"register_operand" "")
              (plus:HI (match_operand:HI 1 
"general_operand" "")
                       (match_operand:HI 2 
"general_operand" "")))]
        "" 

        "") 



(define_insn "*add_all_modes" 

        [(set (match_operand 0 "register_operand" 
"=r")
              (plus (match_operand 1 
"register_operand" "0")
                    (match_operand 2 
"general_operand" "ri")))]
        "" 

	"ADD	%0, %2")




And the error generated by the compiler is:



dct_simple.c:89: error: unrecognizable insn:
(insn/f 412 411 413 0 (parallel [
            (set (reg/f:HI 15 sp)
                (plus:HI (reg/f:HI 15 sp)
                    (const_int 12 [0xc])))
            (clobber (reg:BI 16 carry))
        ]) -1 (nil)
    (expr_list:REG_UNUSED (reg:BI 16 carry)
        (nil)))
dct_simple.c:89: internal compiler error: in 
extract_insn, at recog.c:2083



Any help would be really appreciated!


Regards,

Sami Khawam

The University of Edinburgh
http://www.see.ed.ac.uk/~sxk