m68hc11.md

gcc-you can use this code to learn something about gcc, and inquire further into linux,

(define_split /* "bitcmpqi" */
  [(set (cc0)
	(and:QI (match_operand:QI 0 "tst_operand" "")
		(match_operand:QI 1 "hard_addr_reg_operand" "")))]
  "z_replacement_completed == 2"
  [(set (match_dup 3) (match_dup 2))
   (set (cc0) (and:QI (match_dup 0) (match_dup 4)))]
  "operands[2] = gen_rtx (REG, HImode, REGNO (operands[1]));
   operands[3] = gen_rtx (REG, HImode, SOFT_TMP_REGNUM);
   operands[4] = gen_rtx (REG, QImode, SOFT_TMP_REGNUM);")

(define_insn "bitcmpqi_z_used"
  [(set (cc0)
	(and:QI (match_operand:QI 0 "tst_operand" "d,m")
		(match_operand:QI 1 "cmp_operand" "m,d")))
   (use (match_operand:HI 2 "hard_reg_operand" "xy,xy"))
   (use (reg:HI SOFT_Z_REGNUM))]
  ""
  "#")
  
(define_split /* "bitcmpqi_z_used" */
  [(set (cc0)
	(and:QI (match_operand:QI 0 "tst_operand" "")
		(match_operand:QI 1 "cmp_operand" "")))
   (use (match_operand:HI 2 "hard_reg_operand" ""))
   (use (reg:HI SOFT_Z_REGNUM))]
  "z_replacement_completed == 2"
  [(set (mem:HI (pre_dec:HI (reg:HI SP_REGNUM))) (match_dup 2))
   (set (match_dup 2) (match_dup 3))
   (set (cc0) (and:QI (match_dup 0) (match_dup 1)))
   (set (match_dup 2) (mem:HI (post_inc:HI (reg:HI SP_REGNUM))))]
  "operands[3] = gen_rtx (REG, HImode, SOFT_Z_REGNUM);")

(define_insn "bitcmphi"
  [(set (cc0)
	(and:HI (match_operand:HI 0 "tst_operand" "d")
	        (match_operand:HI 1 "const_int_operand" "i")))]
  "(INTVAL (operands[1]) & 0x0ff) == 0
   || (INTVAL (operands[1]) & 0x0ff00) == 0"
  "*
{
   if ((INTVAL (operands[1]) & 0x0ff) == 0)
     return \"bita\\t%h1\";
   else
     return \"bitb\\t%1\";
}")

(define_insn "bitcmpqi_12"
  [(set (cc0)
	(zero_extract (match_operand:HI 0 "tst_operand" "d")
	              (match_operand:HI 1 "const_int_operand" "i")
		      (match_operand:HI 2 "const_int_operand" "i")))]
  "(unsigned) (INTVAL (operands[2]) + INTVAL (operands[1])) <= 8
   || (((unsigned) (INTVAL (operands[2]) + INTVAL (operands[1])) <= 16)
       && (unsigned) INTVAL (operands[2]) >= 8)"
  "*
{
   rtx ops[1];
   int mask;
   int startpos = INTVAL (operands[2]);
   int bitsize = INTVAL (operands[1]);

   if (startpos >= 8)
     {
       startpos -= 8;
       mask = (1 << (startpos + bitsize)) - 1;
       mask &= ~((1 << startpos) - 1);

       ops[0] = GEN_INT (mask);
       output_asm_insn (\"bita\\t%0\", ops);
     }
   else
     {
       mask = (1 << (startpos + bitsize)) - 1;
       mask &= ~((1 << startpos) - 1);

       ops[0] = GEN_INT (mask);
       output_asm_insn (\"bitb\\t%0\", ops);
     }
   return \"\";
}")

(define_insn "cmpqi_1"
  [(set (cc0)
	(compare (match_operand:QI 0 "tst_operand" "d,m,d,!u,*B,d*B")
		 (match_operand:QI 1 "cmp_operand" "im,d,!u,d,dim*A,*u")))]
  ""
  "*
{
   if (A_REG_P (operands[0]) || A_REG_P (operands[1]))
     {
        return \"#\";
     }
   else if (D_REG_P (operands[0]))
     {
        return \"cmpb\\t%b1\";
     }
   cc_status.flags |= CC_REVERSED;
   return \"cmpb\\t%b0\";
}")

(define_insn "cmpqi_z_used"
  [(set (cc0)
	(compare (match_operand:QI 0 "tst_operand" "dxy,m")
		 (match_operand:QI 1 "cmp_operand" "m,dxy")))
   (use (match_operand:HI 2 "hard_reg_operand" "dxy,dxy"))
   (use (reg:HI SOFT_Z_REGNUM))]
  ""
  "#")
  
(define_split /* cmpqi_z_used */
  [(set (cc0)
	(compare (match_operand:QI 0 "tst_operand" "")
		 (match_operand:QI 1 "cmp_operand" "")))
   (use (match_operand:HI 2 "hard_reg_operand" ""))
   (use (reg:HI SOFT_Z_REGNUM))]
  "z_replacement_completed == 2"
  [(set (mem:HI (pre_dec:HI (reg:HI SP_REGNUM))) (match_dup 2))
   (set (match_dup 2) (match_dup 3))
   (set (cc0) (compare (match_dup 0) (match_dup 1)))
   (set (match_dup 2) (mem:HI (post_inc:HI (reg:HI SP_REGNUM))))]
  "operands[3] = gen_rtx (REG, HImode, SOFT_Z_REGNUM);")

;;--------------------------------------------------------------------
;;-  Move strict_low_part
;;--------------------------------------------------------------------
;;
;; The (strict_low_part ...) patterns are replaced by normal (set) patterns.
;; The replacement must be made at the very end because we loose the
;; (strict_low_part ...) information.  This is correct for our machine
;; description but not for GCC optimization passes.
;;
(define_insn "movstrictsi"
  [(set (strict_low_part (match_operand:SI 0 "non_push_operand" "+um,D,D"))
	(match_operand:SI 1 "general_operand" "D,Dim,uD"))]
  ""
  "#")

(define_split
  [(set (strict_low_part (match_operand:SI 0 "non_push_operand" ""))
	(match_operand:SI 1 "general_operand" ""))]
  "z_replacement_completed == 2"
  [(set (match_dup 0) (match_dup 1))]
  "")

(define_insn "movstricthi"
  [(set (strict_low_part (match_operand:HI 0 "non_push_operand" "+um,dA,dA"))
	(match_operand:HI 1 "general_operand" "dA,dAim,u"))]
  ""
  "#")

(define_split
  [(set (strict_low_part (match_operand:HI 0 "non_push_operand" ""))
	(match_operand:HI 1 "general_operand" ""))]
  "z_replacement_completed == 2"
  [(set (match_dup 0) (match_dup 1))]
  "")

(define_insn "movstrictqi"
  [(set (strict_low_part (match_operand:QI 0 "non_push_operand" "+mu,!dA"))
	(match_operand:QI 1 "general_operand" "d,imudA"))]
  ""
  "#")

(define_split
  [(set (strict_low_part (match_operand:QI 0 "non_push_operand" ""))
	(match_operand:QI 1 "general_operand" ""))]
  "z_replacement_completed == 2"
  [(set (match_dup 0) (match_dup 1))]
  "")

;;--------------------------------------------------------------------
;;- 64-bit Move Operations.
;; The movdi and movdf patterns are identical except for the mode.
;; They are also very similar to those for movsi and movsf.
;;
;; For 68HC11, we need a scratch register (either D, X, Y) 
;; because there is no memory->memory moves.  It must be defined with
;; earlyclobber (&) so that it does not appear in the source or destination 
;; address.  Providing patterns for movdi/movdf allows GCC to generate
;; better code.  [Until now, the scratch register is limited to D because
;; otherwise we can run out of registers in the A_REGS class for reload].
;;
;; For 68HC12, the scratch register is not necessary.  To use the same
;; pattern and same split, we use the 'v' constraint.  This tells the
;; reload to use the _.tmp register (which is not used at all).
;; The insn will be split in one or several memory moves (movw).
;; [SCz: this does not work ?? So, I switched temporary to 'd' reg]
;;--------------------------------------------------------------------
(define_expand "movdi"
  [(parallel [(set (match_operand:DI 0 "nonimmediate_operand" "")
		   (match_operand:DI 1 "general_operand" ""))
	      (clobber (match_scratch:HI 2 ""))])]
  ""
  "
  /* For push/pop, emit a REG_INC note to make sure the reload
     inheritance and reload CSE pass notice the change of the stack
     pointer.  */
  if (IS_STACK_PUSH (operands[0]) || IS_STACK_POP (operands[1]))
    {
      rtx insn;

      insn = emit_insn (gen_movdi_internal (operands[0], operands[1]));
      REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC,
					  stack_pointer_rtx,
					  REG_NOTES (insn));
      DONE;
    }
")

(define_insn "movdi_internal"
  [(set (match_operand:DI 0 "nonimmediate_operand" "=ou,U,!u,U,m,m,!u")
	(match_operand:DI 1 "general_operand" "K,iU,iU,!u,mi,!u,!mu"))
   (clobber (match_scratch:HI 2 "=X,&d,&d,&d,&d,&d,&d"))]
  ""
  "#")

(define_split
  [(set (match_operand:DI 0 "nonimmediate_operand" "")
	(match_operand:DI 1 "general_operand" ""))
   (clobber (match_scratch:HI 2 ""))]
  "reload_completed"
  [(const_int 0)]
  "m68hc11_split_move (operands[0], operands[1], operands[2]);
   DONE;")

(define_expand "movdf"
  [(parallel [(set (match_operand:DF 0 "nonimmediate_operand" "")
		   (match_operand:DF 1 "general_operand" ""))
	      (clobber (match_scratch:HI 2 ""))])]
  ""
  "/* For push/pop, emit a REG_INC note to make sure the reload
      inheritance and reload CSE pass notice the change of the stack
      pointer.  */
  if (IS_STACK_PUSH (operands[0]) || IS_STACK_POP (operands[1]))
    {
      rtx insn;

      insn = emit_insn (gen_movdf_internal (operands[0], operands[1]));
      REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC,
					  stack_pointer_rtx,
					  REG_NOTES (insn));
      DONE;
    }
")

(define_insn "movdf_internal"
  [(set (match_operand:DF 0 "nonimmediate_operand" "=ou,U,!u,U,m,m,!u")
	(match_operand:DF 1 "general_operand" "G,iU,iU,!u,mi,!u,!mu"))
   (clobber (match_scratch:HI 2 "=X,&d,&d,&d,&d,&d,&d"))]
  ""
  "#")

(define_split
  [(set (match_operand:DF 0 "nonimmediate_operand" "")
	(match_operand:DF 1 "general_operand" ""))
   (clobber (match_scratch:HI 2 ""))]
  "reload_completed"
  [(const_int 0)]
  "m68hc11_split_move (operands[0], operands[1], operands[2]);
   DONE;")

;;--------------------------------------------------------------------
;;- 32-bit Move Operations.
;; The movsi and movsf patterns are identical except for the mode.
;; When we move to/from a hard register (d+x), we don't need a scratch.
;; Otherwise, a scratch register is used as intermediate register for
;; the move.  The '&' constraint is necessary to make sure the reload
;; pass does not give us a register that dies in the insn and is used
;; for input/output operands.
;;--------------------------------------------------------------------
(define_expand "movsi"
  [(parallel [(set (match_operand:SI 0 "nonimmediate_operand" "")
		   (match_operand:SI 1 "general_operand" ""))
	      (clobber (match_scratch:HI 2 ""))])]
  ""
  "/* For push/pop, emit a REG_INC note to make sure the reload
      inheritance and reload CSE pass notice the change of the stack
      pointer.  */
  if (IS_STACK_PUSH (operands[0]) || IS_STACK_POP (operands[1]))
    {
      rtx insn;

      insn = emit_insn (gen_movsi_internal (operands[0], operands[1]));
      REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC,
					  stack_pointer_rtx,
					  REG_NOTES (insn));
      DONE;
    }
")

(define_insn "movsi_internal"
  [(set (match_operand:SI 0 "nonimmediate_operand" "=ou,mu,?D,m,?D,?u,?u,!u,D")
	(match_operand:SI 1 "general_operand"      "K,imu,im,?D,!u,?D,mi,!u,!D"))
   (clobber (match_scratch:HI 2                    "=X,&d,X,X,X,X,&d,&d,X"))]
  ""
  "#")

(define_split
  [(set (match_operand:SI 0 "nonimmediate_operand" "")
	(match_operand:SI 1 "general_operand" ""))
   (clobber (match_scratch:HI 2 ""))]
  "reload_completed"
  [(const_int 0)]
  "m68hc11_split_move (operands[0], operands[1], operands[2]);
   DONE;")

(define_expand "movsf"
  [(parallel [(set (match_operand:SF 0 "nonimmediate_operand" "")
		   (match_operand:SF 1 "general_operand" ""))
	      (clobber (match_scratch:HI 2 ""))])]
  ""
  "/* For push/pop, emit a REG_INC note to make sure the reload
      inheritance and reload CSE pass notice the change of the stack
      pointer.  */
  if (IS_STACK_PUSH (operands[0]) || IS_STACK_POP (operands[1]))
    {
      rtx insn;

      insn = emit_insn (gen_movsf_internal (operands[0], operands[1]));
      REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC,
					  stack_pointer_rtx,
					  REG_NOTES (insn));
      DONE;
    }
")

(define_insn "movsf_internal"
  [(set (match_operand:SF 0 "nonimmediate_operand" "=o!u,m,D,m,D,!u,!u,!u,D")
	(match_operand:SF 1 "general_operand" "G,im,im,D,!u,D,mi,!u,!D"))
   (clobber (match_scratch:HI 2 "=X,&d,X,X,X,X,&d,&d,X"))]
  ""
  "#")

(define_split
  [(set (match_operand:SF 0 "nonimmediate_operand" "")
	(match_operand:SF 1 "general_operand" ""))
   (clobber (match_scratch:HI 2 ""))]
  "reload_completed"
  [(const_int 0)]
  "m68hc11_split_move (operands[0], operands[1], operands[2]);
   DONE;")


;;--------------------------------------------------------------------
;;- 16-bit Move Operations.
;; We don't need a scratch register.
;;--------------------------------------------------------------------

(define_insn "*movhi2_push"
  [(set (match_operand:HI 0 "push_operand" "=<,<,<")
	(match_operand:HI 1 "general_operand" "xy,?d,!z"))]
  "TARGET_M6811 && !TARGET_M6812"
  "*
{
  cc_status = cc_prev_status;
  if (D_REG_P (operands[1]))
    {
      output_asm_insn (\"pshb\", operands);
      return \"psha\";
    }
  else if (X_REG_P (operands[1]))
    {
      return \"pshx\";
    }
  else if (Y_REG_P (operands[1]))
    {
      return \"pshy\";
    }
  fatal_insn (\"Invalid register in the instruction\", insn);
}")

(define_insn "*movhi2_pop"
  [(set (match_operand:HI 0 "nonimmediate_operand" "=xy,d")
	(match_operand:HI 1 "pop_operand" ">,>"))]
  "TARGET_M6811"
  "*
{
  cc_status = cc_prev_status;
  if (D_REG_P (operands[0]))
    {
      output_asm_insn (\"pula\", operands);
      return \"pulb\";
    }
  else if (X_REG_P (operands[0]))
    {
      return \"pulx\";
    }
  else if (Y_REG_P (operands[0]))
    {
      return \"puly\";
    }
  fatal_insn (\"Invalid register in the instruction\", insn);
}")

(define_expand "movhi"
  [(set (match_operand:HI 0 "nonimmediate_operand" "")
	(match_operand:HI 1 "general_operand" ""))]
  ""
  "
{
  if (reload_in_progress)
    {
      if (m68hc11_reload_operands (operands))
        {
          DONE;
        }
    }
  if (TARGET_M6811 && (reload_in_progress | reload_completed) == 0)
    {
      if (GET_CODE (operands[0]) == MEM &&
	  (GET_CODE (operands[1]) == MEM
	   || GET_CODE (operands[1]) == CONST_INT))
        {
	  operands[1] = force_reg (HImode, operands[1]);
        }
      else if (IS_STACK_PUSH (operands[0])
	       && GET_CODE (operands[1]) != REG)
        {
	  operands[1] = force_reg (HImode, operands[1]);
        }
    }
  /* For push/pop, emit a REG_INC note to make sure the reload
     inheritance and reload CSE pass notice the change of the stack
     pointer.  */
  if (IS_STACK_PUSH (operands[0]) || IS_STACK_POP (operands[1]))
    {
      rtx insn;

      insn = emit_insn (gen_rtx (SET, VOIDmode, operands[0], operands[1]));
      REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC,
					  stack_pointer_rtx,
					  REG_NOTES (insn));
      DONE;
    }
}")

(define_insn "movhi_const0"
  [(set (match_operand:HI 0 "non_push_operand" "=d,A,um")
	(const_int 0))]
  ""