avr.c

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

/* Output to FILE the asm instructions to adjust the frame pointer by
   ADJ (r29:r28 -= ADJ;) which can be positive (prologue) or negative
   (epilogue).  Returns the number of instructions generated.  */

static int
out_adj_frame_ptr (file, adj)
     FILE *file;
     int adj;
{
  int size = 0;

  if (adj)
    {
      if (TARGET_TINY_STACK)
	{
	  if (adj < -63 || adj > 63)
	    warning ("large frame pointer change (%d) with -mtiny-stack", adj);

	  /* The high byte (r29) doesn't change - prefer "subi" (1 cycle)
	     over "sbiw" (2 cycles, same size).  */

	  fprintf (file, (AS2 (subi, r28, %d) CR_TAB), adj);
	  size++;
	}
      else if (adj < -63 || adj > 63)
	{
	  fprintf (file, (AS2 (subi, r28, lo8(%d)) CR_TAB
			  AS2 (sbci, r29, hi8(%d)) CR_TAB),
		   adj, adj);
	  size += 2;
	}
      else if (adj < 0)
	{
	  fprintf (file, (AS2 (adiw, r28, %d) CR_TAB), -adj);
	  size++;
	}
      else
	{
	  fprintf (file, (AS2 (sbiw, r28, %d) CR_TAB), adj);
	  size++;
	}
    }
  return size;
}


/* Output to FILE the asm instructions to copy r29:r28 to SPH:SPL,
   handling various cases of interrupt enable flag state BEFORE and AFTER
   (0=disabled, 1=enabled, -1=unknown/unchanged) and target_flags.
   Returns the number of instructions generated.  */

static int
out_set_stack_ptr (file, before, after)
     FILE *file;
     int before;
     int after;
{
  int do_sph, do_cli, do_save, do_sei, lock_sph, size;

  /* The logic here is so that -mno-interrupts actually means
     "it is safe to write SPH in one instruction, then SPL in the
     next instruction, without disabling interrupts first".
     The after != -1 case (interrupt/signal) is not affected.  */

  do_sph = !TARGET_TINY_STACK;
  lock_sph = do_sph && !TARGET_NO_INTERRUPTS;
  do_cli = (before != 0 && (after == 0 || lock_sph));
  do_save = (do_cli && before == -1 && after == -1);
  do_sei = ((do_cli || before != 1) && after == 1);
  size = 1;

  if (do_save)
    {
      fprintf (file, AS2 (in, __tmp_reg__, __SREG__) CR_TAB);
      size++;
    }

  if (do_cli)
    {
      fprintf (file, "cli" CR_TAB);
      size++;
    }

  /* Do SPH first - maybe this will disable interrupts for one instruction
     someday (a suggestion has been sent to [e-mail] for consideration
     in future devices - that would make -mno-interrupts always safe).  */
  if (do_sph)
    {
      fprintf (file, AS2 (out, __SP_H__, r29) CR_TAB);
      size++;
    }

  /* Set/restore the I flag now - interrupts will be really enabled only
     after the next instruction.  This is not clearly documented, but
     believed to be true for all AVR devices.  */
  if (do_save)
    {
      fprintf (file, AS2 (out, __SREG__, __tmp_reg__) CR_TAB);
      size++;
    }
  else if (do_sei)
    {
      fprintf (file, "sei" CR_TAB);
      size++;
    }

  fprintf (file, AS2 (out, __SP_L__, r28) "\n");

  return size;
}


/* Output function prologue */

static void
avr_output_function_prologue (file, size)
     FILE *file;
     HOST_WIDE_INT size;
{
  int reg;
  int interrupt_func_p;
  int signal_func_p;
  int main_p;
  int live_seq;
  int minimize;

  last_insn_address = 0;
  jump_tables_size = 0;
  prologue_size = 0;
  fprintf (file, "/* prologue: frame size=%d */\n", size);

  if (avr_naked_function_p (current_function_decl))
    {
      fputs ("/* prologue: naked */\n", file);
      goto out;
    }

  interrupt_func_p = interrupt_function_p (current_function_decl);
  signal_func_p = signal_function_p (current_function_decl);
  main_p = MAIN_NAME_P (DECL_NAME (current_function_decl));
  live_seq = sequent_regs_live ();
  minimize = (TARGET_CALL_PROLOGUES
	      && !interrupt_func_p && !signal_func_p && live_seq);

  if (interrupt_func_p)
    {
      fprintf (file,"\tsei\n");
      ++prologue_size;
    }
  if (interrupt_func_p || signal_func_p)
    {
      fprintf (file, "\t"
               AS1 (push,__zero_reg__)   CR_TAB
               AS1 (push,__tmp_reg__)    CR_TAB
	       AS2 (in,__tmp_reg__,__SREG__) CR_TAB
	       AS1 (push,__tmp_reg__)    CR_TAB
	       AS1 (clr,__zero_reg__)    "\n");
      prologue_size += 5;
    }
  if (main_p)
    {
      fprintf (file, ("\t" 
		      AS2 (ldi,r28,lo8(%s - %d)) CR_TAB
		      AS2 (ldi,r29,hi8(%s - %d)) CR_TAB
		      AS2 (out,__SP_H__,r29)     CR_TAB
		      AS2 (out,__SP_L__,r28) "\n"),
	       avr_init_stack, size, avr_init_stack, size);
      
      prologue_size += 4;
    }
  else if (minimize && (frame_pointer_needed || live_seq > 6)) 
    {
      fprintf (file, ("\t"
		      AS2 (ldi, r26, lo8(%d)) CR_TAB
		      AS2 (ldi, r27, hi8(%d)) CR_TAB), size, size);

      fprintf (file, (AS2 (ldi, r30, pm_lo8(.L_%s_body)) CR_TAB
		      AS2 (ldi, r31, pm_hi8(.L_%s_body)) CR_TAB)
	       ,current_function_name, current_function_name);
      
      prologue_size += 4;
      
      if (AVR_MEGA)
	{
	  fprintf (file, AS1 (jmp,__prologue_saves__+%d) "\n",
		   (18 - live_seq) * 2);
	  prologue_size += 2;
	}
      else
	{
	  fprintf (file, AS1 (rjmp,__prologue_saves__+%d) "\n",
		   (18 - live_seq) * 2);
	  ++prologue_size;
	}
      fprintf (file, ".L_%s_body:\n", current_function_name);
    }
  else
    {
      HARD_REG_SET set;

      prologue_size += avr_regs_to_save (&set);
      for (reg = 0; reg < 32; ++reg)
	{
	  if (TEST_HARD_REG_BIT (set, reg))
	    {
	      fprintf (file, "\t" AS1 (push,%s) "\n", avr_regnames[reg]);
	    }
	}
      if (frame_pointer_needed)
	{
	  {
	    fprintf (file, "\t"
		     AS1 (push,r28) CR_TAB
		     AS1 (push,r29) CR_TAB
		     AS2 (in,r28,__SP_L__) CR_TAB
		     AS2 (in,r29,__SP_H__) "\n");
	    prologue_size += 4;
	    if (size)
	      {
		fputs ("\t", file);
		prologue_size += out_adj_frame_ptr (file, size);

		if (interrupt_func_p)
		  {
		    prologue_size += out_set_stack_ptr (file, 1, 1);
		  }
		else if (signal_func_p)
		  {
		    prologue_size += out_set_stack_ptr (file, 0, 0);
		  }
		else
		  {
		    prologue_size += out_set_stack_ptr (file, -1, -1);
		  }
	      }
	  }
	}
    }

 out:
  fprintf (file, "/* prologue end (size=%d) */\n", prologue_size);
}

/* Output function epilogue */

static void
avr_output_function_epilogue (file, size)
     FILE *file;
     HOST_WIDE_INT size;
{
  int reg;
  int interrupt_func_p;
  int signal_func_p;
  int main_p;
  int function_size;
  int live_seq;
  int minimize;
  rtx last = get_last_nonnote_insn ();

  function_size = jump_tables_size;
  if (last)
    {
      rtx first = get_first_nonnote_insn ();
      function_size += (INSN_ADDRESSES (INSN_UID (last)) -
			INSN_ADDRESSES (INSN_UID (first)));
      function_size += get_attr_length (last);
    }

  fprintf (file, "/* epilogue: frame size=%d */\n", size);
  epilogue_size = 0;

  if (avr_naked_function_p (current_function_decl))
    {
      fputs ("/* epilogue: naked */\n", file);
      goto out;
    }

  if (last && GET_CODE (last) == BARRIER)
    {
      fputs ("/* epilogue: noreturn */\n", file);
      goto out;
    }

  interrupt_func_p = interrupt_function_p (current_function_decl);
  signal_func_p = signal_function_p (current_function_decl);
  main_p = MAIN_NAME_P (DECL_NAME (current_function_decl));
  live_seq = sequent_regs_live ();
  minimize = (TARGET_CALL_PROLOGUES
	      && !interrupt_func_p && !signal_func_p && live_seq);
  
  if (main_p)
    {
      /* Return value from main() is already in the correct registers
	 (r25:r24) as the exit() argument.  */
      if (AVR_MEGA)
	{
	  fputs ("\t" AS1 (jmp,exit) "\n", file);
	  epilogue_size += 2;
	}
      else
	{
	  fputs ("\t" AS1 (rjmp,exit) "\n", file);
	  ++epilogue_size;
	}
    }
  else if (minimize && (frame_pointer_needed || live_seq > 4))
    {
      fprintf (file, ("\t" AS2 (ldi, r30, %d) CR_TAB), live_seq);
      ++epilogue_size;
      if (frame_pointer_needed)
	{
	  epilogue_size += out_adj_frame_ptr (file, -size);
	}
      else
	{
	  fprintf (file, (AS2 (in , r28, __SP_L__) CR_TAB
			  AS2 (in , r29, __SP_H__) CR_TAB));
	  epilogue_size += 2;
	}
      
      if (AVR_MEGA)
	{
	  fprintf (file, AS1 (jmp,__epilogue_restores__+%d) "\n",
		   (18 - live_seq) * 2);
	  epilogue_size += 2;
	}
      else
	{
	  fprintf (file, AS1 (rjmp,__epilogue_restores__+%d) "\n",
		   (18 - live_seq) * 2);
	  ++epilogue_size;
	}
    }
  else
    {
      HARD_REG_SET set;

      if (frame_pointer_needed)
	{
	  if (size)
	    {
	      fputs ("\t", file);
	      epilogue_size += out_adj_frame_ptr (file, -size);

	      if (interrupt_func_p || signal_func_p)
		{
		  epilogue_size += out_set_stack_ptr (file, -1, 0);
		}
	      else
		{
		  epilogue_size += out_set_stack_ptr (file, -1, -1);
		}
	    }
	  fprintf (file, "\t"
		   AS1 (pop,r29) CR_TAB
		   AS1 (pop,r28) "\n");
	  epilogue_size += 2;
	}

      epilogue_size += avr_regs_to_save (&set);
      for (reg = 31; reg >= 0; --reg)
	{
	  if (TEST_HARD_REG_BIT (set, reg))
	    {
	      fprintf (file, "\t" AS1 (pop,%s) "\n", avr_regnames[reg]);
	    }
	}

      if (interrupt_func_p || signal_func_p)
	{
	  fprintf (file, "\t"
		   AS1 (pop,__tmp_reg__)      CR_TAB
		   AS2 (out,__SREG__,__tmp_reg__) CR_TAB
		   AS1 (pop,__tmp_reg__)      CR_TAB
		   AS1 (pop,__zero_reg__)     "\n");
	  epilogue_size += 4;
	  fprintf (file, "\treti\n");
	}
      else
	fprintf (file, "\tret\n");
      ++epilogue_size;
    }

 out:
  fprintf (file, "/* epilogue end (size=%d) */\n", epilogue_size);
  fprintf (file, "/* function %s size %d (%d) */\n", current_function_name,
	   prologue_size + function_size + epilogue_size, function_size);
  commands_in_file += prologue_size + function_size + epilogue_size;
  commands_in_prologues += prologue_size;
  commands_in_epilogues += epilogue_size;
}


/* Return nonzero if X (an RTX) is a legitimate memory address on the target
   machine for a memory operand of mode MODE.  */

int
legitimate_address_p (mode, x, strict)
     enum machine_mode mode;
     rtx x;
     int strict;
{
  enum reg_class r = NO_REGS;
  
  if (TARGET_ALL_DEBUG)
    {
      fprintf (stderr, "mode: (%s) %s %s %s %s:",
	       GET_MODE_NAME(mode),
	       strict ? "(strict)": "",
	       reload_completed ? "(reload_completed)": "",
	       reload_in_progress ? "(reload_in_progress)": "",
	       reg_renumber ? "(reg_renumber)" : "");
      if (GET_CODE (x) == PLUS
	  && REG_P (XEXP (x, 0))
	  && GET_CODE (XEXP (x, 1)) == CONST_INT
	  && INTVAL (XEXP (x, 1)) >= 0
	  && INTVAL (XEXP (x, 1)) <= MAX_LD_OFFSET (mode)
	  && reg_renumber
	  )
	fprintf (stderr, "(r%d ---> r%d)", REGNO (XEXP (x, 0)),
		 true_regnum (XEXP (x, 0)));
      debug_rtx (x);
    }
  if (REG_P (x) && (strict ? REG_OK_FOR_BASE_STRICT_P (x)
                    : REG_OK_FOR_BASE_NOSTRICT_P (x)))
    r = POINTER_REGS;
  else if (CONSTANT_ADDRESS_P (x))
    r = ALL_REGS;
  else if (GET_CODE (x) == PLUS
           && REG_P (XEXP (x, 0))
	   && GET_CODE (XEXP (x, 1)) == CONST_INT
	   && INTVAL (XEXP (x, 1)) >= 0)
    {
      int fit = INTVAL (XEXP (x, 1)) <= MAX_LD_OFFSET (mode);
      if (fit)
	{
	  if (! strict
	      || REGNO (XEXP (x,0)) == REG_Y
	      || REGNO (XEXP (x,0)) == REG_Z)
	    r = BASE_POINTER_REGS;
	  if (XEXP (x,0) == frame_pointer_rtx
	      || XEXP (x,0) == arg_pointer_rtx)
	    r = BASE_POINTER_REGS;
	}
      else if (frame_pointer_needed && XEXP (x,0) == frame_pointer_rtx)
	r = POINTER_Y_REGS;
    }
  else if ((GET_CODE (x) == PRE_DEC || GET_CODE (x) == POST_INC)
           && REG_P (XEXP (x, 0))
           && (strict ? REG_OK_FOR_BASE_STRICT_P (XEXP (x, 0))
               : REG_OK_FOR_BASE_NOSTRICT_P (XEXP (x, 0))))
    {
      r = POINTER_REGS;
    }
  if (TARGET_ALL_DEBUG)
    {
      fprintf (stderr, "   ret = %c\n", r);
    }
  return r == NO_REGS ? 0 : (int)r;
}

/* Attempts to replace X with a valid
   memory address for an operand of mode MODE  */

rtx
legitimize_address (x, oldx, mode)
     rtx x;
     rtx oldx;
     enum machine_mode mode;
{
  x = oldx;
  if (TARGET_ALL_DEBUG)
    {
      fprintf (stderr, "legitimize_address mode: %s", GET_MODE_NAME(mode));
      debug_rtx (oldx);
    }
  
  if (GET_CODE (oldx) == PLUS
      && REG_P (XEXP (oldx,0)))
    {
      if (REG_P (XEXP (oldx,1)))
	x = force_reg (GET_MODE (oldx), oldx);
      else if (GET_CODE (XEXP (oldx, 1)) == CONST_INT)
	{
	  int offs = INTVAL (XEXP (oldx,1));
	  if (frame_pointer_rtx != XEXP (oldx,0))
	    if (offs > MAX_LD_OFFSET (mode))
	      {
		if (TARGET_ALL_DEBUG)
		  fprintf (stderr, "force_reg (big offset)\n");
		x = force_reg (GET_MODE (oldx), oldx);
	      }
	}
    }
  return x;
}


/* Return a pointer register name as a string */

static const char *
ptrreg_to_str (regno)
     int regno;
{
  switch (regno)
    {
    case REG_X: return "X";
    case REG_Y: return "Y";
    case REG_Z: return "Z";