m88k.c

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  /* If a frame is requested, save the previous FP, and the return
     address (r1), so that a traceback can be done without using tdesc
     information.  Otherwise, simply save the FP if it is used as
     a preserve register.  */
  if (frame_pointer_needed)
    save_regs[FRAME_POINTER_REGNUM] = save_regs[1] = 1;
  else if (regs_ever_live[FRAME_POINTER_REGNUM])
    save_regs[FRAME_POINTER_REGNUM] = 1;

  /* Figure out which extended register(s) needs to be saved.  */
  for (regno = FIRST_EXTENDED_REGISTER + 1; regno < FIRST_PSEUDO_REGISTER;
       regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      {
	save_regs[regno] = 1;
	nxregs++;
      }

  /* Figure out which normal register(s) needs to be saved.  */
  for (regno = 2; regno < FRAME_POINTER_REGNUM; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      {
	save_regs[regno] = 1;
	nregs++;
      }

  /* Achieve greatest use of double memory ops.  Either we end up saving
     r30 or we use that slot to align the registers we do save.  */
  if (nregs >= 2 && save_regs[1] && !save_regs[FRAME_POINTER_REGNUM])
    sp_size += 4;

  nregs += save_regs[1] + save_regs[FRAME_POINTER_REGNUM];
  /* if we need to align extended registers, add a word */
  if (nxregs > 0 && (nregs & 1) != 0)
    sp_size +=4;
  sp_size += 4 * nregs;
  sp_size += 8 * nxregs;
  sp_size += current_function_outgoing_args_size;

  /* The first two saved registers are placed above the new frame pointer
     if any.  In the only case this matters, they are r1 and r30. */
  if (frame_pointer_needed || sp_size)
    m88k_fp_offset = ROUND_CALL_BLOCK_SIZE (sp_size - STARTING_FRAME_OFFSET);
  else
    m88k_fp_offset = -STARTING_FRAME_OFFSET;
  m88k_stack_size = m88k_fp_offset + STARTING_FRAME_OFFSET;

  /* First, combine m88k_stack_size and size.  If m88k_stack_size is
     nonzero, align the frame size to 8 mod 16; otherwise align the
     frame size to 0 mod 16.  (If stacks are 8 byte aligned, this ends
     up as a NOP.  */
  {
    int need
      = ((m88k_stack_size ? STACK_UNIT_BOUNDARY - STARTING_FRAME_OFFSET : 0)
	 - (frame_size % STACK_UNIT_BOUNDARY));
    if (need < 0)
      need += STACK_UNIT_BOUNDARY;
    m88k_stack_size
      = ROUND_CALL_BLOCK_SIZE (m88k_stack_size + frame_size + need
			       + current_function_pretend_args_size);
  }
}

/* Return true if this function is known to have a null prologue.  */

int
null_prologue ()
{
  if (! reload_completed)
    return 0;
  if (! frame_laid_out)
    m88k_layout_frame ();
  return (! frame_pointer_needed
	  && nregs == 0
	  && nxregs == 0
	  && m88k_stack_size == 0);
}

/* Determine if the current function has any references to the arg pointer.
   This is done indirectly by examining the DECL_ARGUMENTS' DECL_RTL.
   It is OK to return TRUE if there are no references, but FALSE must be
   correct.  */

static int
uses_arg_area_p ()
{
  register tree parm;

  if (current_function_decl == 0
      || variable_args_p)
    return 1;

  for (parm = DECL_ARGUMENTS (current_function_decl);
       parm;
       parm = TREE_CHAIN (parm))
    {
      if (DECL_RTL (parm) == 0
	  || GET_CODE (DECL_RTL (parm)) == MEM)
	return 1;

      if (DECL_INCOMING_RTL (parm) == 0
	  || GET_CODE (DECL_INCOMING_RTL (parm)) == MEM)
	return 1;
    }
  return 0;
}

static void
m88k_output_function_prologue (stream, size)
     FILE *stream ATTRIBUTE_UNUSED;
     HOST_WIDE_INT size ATTRIBUTE_UNUSED;
{
  if (TARGET_OMIT_LEAF_FRAME_POINTER && ! quiet_flag && leaf_function_p ())
    fprintf (stderr, "$");

  m88k_prologue_done = 1;	/* it's ok now to put out ln directives */
}

static void
m88k_output_function_end_prologue (stream)
     FILE *stream;
{
  if (TARGET_OCS_DEBUG_INFO && !prologue_marked)
    {
      PUT_OCS_FUNCTION_START (stream);
      prologue_marked = 1;

      /* If we've already passed the start of the epilogue, say that
	 it starts here.  This marks the function as having a null body,
	 but at a point where the return address is in a known location.

	 Originally, I thought this couldn't happen, but the pic prologue
	 for leaf functions ends with the instruction that restores the
	 return address from the temporary register.  If the temporary
	 register is never used, that instruction can float all the way
	 to the end of the function.  */
      if (epilogue_marked)
	PUT_OCS_FUNCTION_END (stream);
    }
}

void
m88k_expand_prologue ()
{
  m88k_layout_frame ();

  if (TARGET_OPTIMIZE_ARG_AREA
      && m88k_stack_size
      && ! uses_arg_area_p ())
    {
      /* The incoming argument area is used for stack space if it is not
	 used (or if -mno-optimize-arg-area is given).  */
      if ((m88k_stack_size -= REG_PARM_STACK_SPACE (0)) < 0)
	m88k_stack_size = 0;
    }

  if (m88k_stack_size)
    emit_add (stack_pointer_rtx, stack_pointer_rtx, -m88k_stack_size);

  if (nregs || nxregs)
    preserve_registers (m88k_fp_offset + 4, 1);

  if (frame_pointer_needed)
    emit_add (frame_pointer_rtx, stack_pointer_rtx, m88k_fp_offset);

  if (flag_pic && save_regs[PIC_OFFSET_TABLE_REGNUM])
    {
      rtx return_reg = gen_rtx_REG (SImode, 1);
      rtx label = gen_label_rtx ();
      rtx temp_reg = NULL_RTX;

      if (! save_regs[1])
	{
	  temp_reg = gen_rtx_REG (SImode, TEMP_REGNUM);
	  emit_move_insn (temp_reg, return_reg);
	}
      emit_insn (gen_locate1 (pic_offset_table_rtx, label));
      emit_insn (gen_locate2 (pic_offset_table_rtx, label));
      emit_insn (gen_addsi3 (pic_offset_table_rtx,
			     pic_offset_table_rtx, return_reg));
      if (! save_regs[1])
	emit_move_insn (return_reg, temp_reg);
    }
  if (current_function_profile)
    emit_insn (gen_blockage ());
}

/* This function generates the assembly code for function exit,
   on machines that need it.

   The function epilogue should not depend on the current stack pointer!
   It should use the frame pointer only, if there is a frame pointer.
   This is mandatory because of alloca; we also take advantage of it to
   omit stack adjustments before returning.  */

static void
m88k_output_function_begin_epilogue (stream)
     FILE *stream;
{
  if (TARGET_OCS_DEBUG_INFO && !epilogue_marked && prologue_marked)
    {
      PUT_OCS_FUNCTION_END (stream);
    }
  epilogue_marked = 1;
}

static void
m88k_output_function_epilogue (stream, size)
     FILE *stream;
     HOST_WIDE_INT size ATTRIBUTE_UNUSED;
{
  rtx insn = get_last_insn ();

  if (TARGET_OCS_DEBUG_INFO && !epilogue_marked)
    PUT_OCS_FUNCTION_END (stream);

  /* If the last insn isn't a BARRIER, we must write a return insn.  This
     should only happen if the function has no prologue and no body.  */
  if (GET_CODE (insn) == NOTE)
    insn = prev_nonnote_insn (insn);
  if (insn == 0 || GET_CODE (insn) != BARRIER)
    fprintf (stream, "\tjmp\t %s\n", reg_names[1]);

  /* If the last insn is a barrier, and the insn before that is a call,
     then add a nop instruction so that tdesc can walk the stack correctly
     even though there is no epilogue. (Otherwise, the label for the
     end of the tdesc region ends up at the start of the next function. */
  if (insn && GET_CODE (insn) == BARRIER)
    {
      insn = prev_nonnote_insn (insn);
      if (insn && GET_CODE (insn) == CALL_INSN)
        fprintf (stream, "\tor\t %s,%s,%s\n",reg_names[0],reg_names[0],reg_names[0]);
    }

  output_short_branch_defs (stream);

  fprintf (stream, "\n");

  if (TARGET_OCS_DEBUG_INFO)
    output_tdesc (stream, m88k_fp_offset + 4);

  m88k_function_number++;
  m88k_prologue_done	= 0;		/* don't put out ln directives */
  variable_args_p	= 0;		/* has variable args */
  frame_laid_out	= 0;
  epilogue_marked	= 0;
  prologue_marked	= 0;
}

void
m88k_expand_epilogue ()
{
#if (MONITOR_GCC & 0x4) /* What are interesting prologue/epilogue values?  */
  fprintf (stream, "; size = %d, m88k_fp_offset = %d, m88k_stack_size = %d\n",
	   size, m88k_fp_offset, m88k_stack_size);
#endif

  if (frame_pointer_needed)
    emit_add (stack_pointer_rtx, frame_pointer_rtx, -m88k_fp_offset);

  if (nregs || nxregs)
    preserve_registers (m88k_fp_offset + 4, 0);

  if (m88k_stack_size)
    emit_add (stack_pointer_rtx, stack_pointer_rtx, m88k_stack_size);
}

/* Emit insns to set DSTREG to SRCREG + AMOUNT during the prologue or
   epilogue.  */

static void
emit_add (dstreg, srcreg, amount)
     rtx dstreg;
     rtx srcreg;
     int amount;
{
  rtx incr = GEN_INT (abs (amount));

  if (! ADD_INTVAL (amount))
    {
      rtx temp = gen_rtx_REG (SImode, TEMP_REGNUM);
      emit_move_insn (temp, incr);
      incr = temp;
    }
  emit_insn ((amount < 0 ? gen_subsi3 : gen_addsi3) (dstreg, srcreg, incr));
}

/* Save/restore the preserve registers.  base is the highest offset from
   r31 at which a register is stored.  store_p is true if stores are to
   be done; otherwise loads.  */

static void
preserve_registers (base, store_p)
     int base;
     int store_p;
{
  int regno, offset;
  struct mem_op {
    int regno;
    int nregs;
    int offset;
  } mem_op[FIRST_PSEUDO_REGISTER];
  struct mem_op *mo_ptr = mem_op;

  /* The 88open OCS mandates that preserved registers be stored in
     increasing order.  For compatibility with current practice,
     the order is r1, r30, then the preserve registers.  */

  offset = base;
  if (save_regs[1])
    {
      /* An extra word is given in this case to make best use of double
	 memory ops.  */
      if (nregs > 2 && !save_regs[FRAME_POINTER_REGNUM])
	offset -= 4;
      emit_ldst (store_p, 1, SImode, offset);
      offset -= 4;
      base = offset;
    }

  /* Walk the registers to save recording all single memory operations.  */
  for (regno = FRAME_POINTER_REGNUM; regno > 1; regno--)
    if (save_regs[regno])
      {
	if ((offset & 7) != 4 || (regno & 1) != 1 || !save_regs[regno-1])
	  {
	    mo_ptr->nregs = 1;
	    mo_ptr->regno = regno;
	    mo_ptr->offset = offset;
	    mo_ptr++;
	    offset -= 4;
	  }
        else
	  {
	    regno--;
	    offset -= 2*4;
	  }
      }

  /* Walk the registers to save recording all double memory operations.
     This avoids a delay in the epilogue (ld.d/ld).  */
  offset = base;
  for (regno = FRAME_POINTER_REGNUM; regno > 1; regno--)
    if (save_regs[regno])
      {
	if ((offset & 7) != 4 || (regno & 1) != 1 || !save_regs[regno-1])
	  {
	    offset -= 4;
	  }
        else
	  {
	    mo_ptr->nregs = 2;
	    mo_ptr->regno = regno-1;
	    mo_ptr->offset = offset-4;
	    mo_ptr++;
	    regno--;
	    offset -= 2*4;
	  }
      }

  /* Walk the extended registers to record all memory operations.  */
  /*  Be sure the offset is double word aligned.  */
  offset = (offset - 1) & ~7;
  for (regno = FIRST_PSEUDO_REGISTER - 1; regno > FIRST_EXTENDED_REGISTER;
       regno--)
    if (save_regs[regno])
      {
	mo_ptr->nregs = 2;
	mo_ptr->regno = regno;
	mo_ptr->offset = offset;
	mo_ptr++;
	offset -= 2*4;
      }

  mo_ptr->regno = 0;

  /* Output the memory operations.  */
  for (mo_ptr = mem_op; mo_ptr->regno; mo_ptr++)
    {
      if (mo_ptr->nregs)
	emit_ldst (store_p, mo_ptr->regno,
		   (mo_ptr->nregs > 1 ? DImode : SImode),
		   mo_ptr->offset);
    }
}

static void
emit_ldst (store_p, regno, mode, offset)
     int store_p;
     int regno;
     enum machine_mode mode;
     int offset;
{
  rtx reg = gen_rtx_REG (mode, regno);
  rtx mem;

  if (SMALL_INTVAL (offset))
    {
      mem = gen_rtx_MEM (mode, plus_constant (stack_pointer_rtx, offset));
    }
  else
    {
      /* offset is too large for immediate index must use register */

      rtx disp = GEN_INT (offset);
      rtx temp = gen_rtx_REG (SImode, TEMP_REGNUM);
      rtx regi = gen_rtx_PLUS (SImode, stack_pointer_rtx, temp);

      emit_move_insn (temp, disp);
      mem = gen_rtx_MEM (mode, regi);
    }

  if (store_p)
    emit_move_insn (mem, reg);
  else
    emit_move_insn (reg, mem);
}

/* Convert the address expression REG to a CFA offset.  */

int
m88k_debugger_offset (reg, offset)
     register rtx reg;
     register int offset;
{
  if (GET_CODE (reg) == PLUS)
    {
      offset = INTVAL (XEXP (reg, 1));
      reg = XEXP (reg, 0);
    }

  /* Put the offset in terms of the CFA (arg pointer).  */
  if (reg == frame_pointer_rtx)
    offset += m88k_fp_offset - m88k_stack_size;
  else if (reg == stack_pointer_rtx)
    offset -= m88k_stack_size;
  else if (reg != arg_pointer_rtx)
    {
#if (MONITOR_GCC & 0x10) /* Watch for suspicious symbolic locations.  */
      if (! (GET_CODE (reg) == REG
	     && REGNO (reg) >= FIRST_PSEUDO_REGISTER))
	warning ("internal gcc error: Can't express symbolic location");
#endif
      return 0;
    }

  return offset;
}

/* Output the 88open OCS proscribed text description information.
   The information is:
        0  8: zero
	0 22: info-byte-length (16 or 20 bytes)
	0  2: info-alignment (word 2)
	1 32: info-protocol (version 1 or 2(pic))
	2 32: starting-address (inclusive, not counting prologue)
	3 32: ending-address (exclusive, not counting epilog)
	4  8: info-variant (version 1 or 3(extended registers))
	4 17: register-save-mask (from register 14 to 30)
	4  1: zero
	4  1: return-address-info-discrimin