bfin.c

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      if (lookup_attribute ("nesting", attrs))
	n++;

      for (i = REG_P7 + 1; i < REG_CC; i++)
	if (all 
	    || regs_ever_live[i]
	    || (!leaf_function_p () && call_used_regs[i]))
	  n += i == REG_A0 || i == REG_A1 ? 2 : 1;
    }
  return n;
}

/* Return the offset between two registers, one to be eliminated, and the other
   its replacement, at the start of a routine.  */

HOST_WIDE_INT
bfin_initial_elimination_offset (int from, int to)
{
  HOST_WIDE_INT offset = 0;

  if (from == ARG_POINTER_REGNUM)
    offset = n_regs_saved_by_prologue () * 4;

  if (to == STACK_POINTER_REGNUM)
    {
      if (current_function_outgoing_args_size >= FIXED_STACK_AREA)
	offset += current_function_outgoing_args_size;
      else if (current_function_outgoing_args_size)
	offset += FIXED_STACK_AREA;

      offset += get_frame_size ();
    }

  return offset;
}

/* Emit code to load a constant CONSTANT into register REG; setting
   RTX_FRAME_RELATED_P on all insns we generate if RELATED is true.
   Make sure that the insns we generate need not be split.  */

static void
frame_related_constant_load (rtx reg, HOST_WIDE_INT constant, bool related)
{
  rtx insn;
  rtx cst = GEN_INT (constant);

  if (constant >= -32768 && constant < 65536)
    insn = emit_move_insn (reg, cst);
  else
    {
      /* We don't call split_load_immediate here, since dwarf2out.c can get
	 confused about some of the more clever sequences it can generate.  */
      insn = emit_insn (gen_movsi_high (reg, cst));
      if (related)
	RTX_FRAME_RELATED_P (insn) = 1;
      insn = emit_insn (gen_movsi_low (reg, reg, cst));
    }
  if (related)
    RTX_FRAME_RELATED_P (insn) = 1;
}

/* Generate efficient code to add a value to the frame pointer.  We
   can use P1 as a scratch register.  Set RTX_FRAME_RELATED_P on the
   generated insns if FRAME is nonzero.  */

static void
add_to_sp (rtx spreg, HOST_WIDE_INT value, int frame)
{
  if (value == 0)
    return;

  /* Choose whether to use a sequence using a temporary register, or
     a sequence with multiple adds.  We can add a signed 7 bit value
     in one instruction.  */
  if (value > 120 || value < -120)
    {
      rtx tmpreg = gen_rtx_REG (SImode, REG_P1);
      rtx insn;

      if (frame)
	frame_related_constant_load (tmpreg, value, TRUE);
      else
	{
	  insn = emit_move_insn (tmpreg, GEN_INT (value));
	  if (frame)
	    RTX_FRAME_RELATED_P (insn) = 1;
	}

      insn = emit_insn (gen_addsi3 (spreg, spreg, tmpreg));
      if (frame)
	RTX_FRAME_RELATED_P (insn) = 1;
    }
  else
    do
      {
	int size = value;
	rtx insn;

	if (size > 60)
	  size = 60;
	else if (size < -60)
	  /* We could use -62, but that would leave the stack unaligned, so
	     it's no good.  */
	  size = -60;

	insn = emit_insn (gen_addsi3 (spreg, spreg, GEN_INT (size)));
	if (frame)
	  RTX_FRAME_RELATED_P (insn) = 1;
	value -= size;
      }
    while (value != 0);
}

/* Generate a LINK insn for a frame sized FRAME_SIZE.  If this constant
   is too large, generate a sequence of insns that has the same effect.
   SPREG contains (reg:SI REG_SP).  */

static void
emit_link_insn (rtx spreg, HOST_WIDE_INT frame_size)
{
  HOST_WIDE_INT link_size = frame_size;
  rtx insn;
  int i;

  if (link_size > 262140)
    link_size = 262140;

  /* Use a LINK insn with as big a constant as possible, then subtract
     any remaining size from the SP.  */
  insn = emit_insn (gen_link (GEN_INT (-8 - link_size)));
  RTX_FRAME_RELATED_P (insn) = 1;

  for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
    {
      rtx set = XVECEXP (PATTERN (insn), 0, i);
      gcc_assert (GET_CODE (set) == SET);
      RTX_FRAME_RELATED_P (set) = 1;
    }

  frame_size -= link_size;

  if (frame_size > 0)
    {
      /* Must use a call-clobbered PREG that isn't the static chain.  */
      rtx tmpreg = gen_rtx_REG (Pmode, REG_P1);

      frame_related_constant_load (tmpreg, -frame_size, TRUE);
      insn = emit_insn (gen_addsi3 (spreg, spreg, tmpreg));
      RTX_FRAME_RELATED_P (insn) = 1;
    }
}

/* Return the number of bytes we must reserve for outgoing arguments
   in the current function's stack frame.  */

static HOST_WIDE_INT
arg_area_size (void)
{
  if (current_function_outgoing_args_size)
    {
      if (current_function_outgoing_args_size >= FIXED_STACK_AREA)
	return current_function_outgoing_args_size;
      else
	return FIXED_STACK_AREA;
    }
  return 0;
}

/* Save RETS and FP, and allocate a stack frame.  ALL is true if the
   function must save all its registers (true only for certain interrupt
   handlers).  */

static void
do_link (rtx spreg, HOST_WIDE_INT frame_size, bool all)
{
  frame_size += arg_area_size ();

  if (all || stack_frame_needed_p ()
      || (must_save_fp_p () && ! current_function_is_leaf))
    emit_link_insn (spreg, frame_size);
  else
    {
      if (! current_function_is_leaf)
	{
	  rtx pat = gen_movsi (gen_rtx_MEM (Pmode,
					    gen_rtx_PRE_DEC (Pmode, spreg)),
			       bfin_rets_rtx);
	  rtx insn = emit_insn (pat);
	  RTX_FRAME_RELATED_P (insn) = 1;
	}
      if (must_save_fp_p ())
	{
	  rtx pat = gen_movsi (gen_rtx_MEM (Pmode,
					    gen_rtx_PRE_DEC (Pmode, spreg)),
			       gen_rtx_REG (Pmode, REG_FP));
	  rtx insn = emit_insn (pat);
	  RTX_FRAME_RELATED_P (insn) = 1;
	}
      add_to_sp (spreg, -frame_size, 1);
    }
}

/* Like do_link, but used for epilogues to deallocate the stack frame.  */

static void
do_unlink (rtx spreg, HOST_WIDE_INT frame_size, bool all)
{
  frame_size += arg_area_size ();

  if (all || stack_frame_needed_p ())
    emit_insn (gen_unlink ());
  else 
    {
      rtx postinc = gen_rtx_MEM (Pmode, gen_rtx_POST_INC (Pmode, spreg));

      add_to_sp (spreg, frame_size, 0);
      if (must_save_fp_p ())
	{
	  rtx fpreg = gen_rtx_REG (Pmode, REG_FP);
	  emit_move_insn (fpreg, postinc);
	  emit_insn (gen_rtx_USE (VOIDmode, fpreg));
	}
      if (! current_function_is_leaf)
	{
	  emit_move_insn (bfin_rets_rtx, postinc);
	  emit_insn (gen_rtx_USE (VOIDmode, bfin_rets_rtx));
	}
    }
}

/* Generate a prologue suitable for a function of kind FKIND.  This is
   called for interrupt and exception handler prologues.
   SPREG contains (reg:SI REG_SP).  */

static void
expand_interrupt_handler_prologue (rtx spreg, e_funkind fkind)
{
  int i;
  HOST_WIDE_INT frame_size = get_frame_size ();
  rtx predec1 = gen_rtx_PRE_DEC (SImode, spreg);
  rtx predec = gen_rtx_MEM (SImode, predec1);
  rtx insn;
  tree attrs = TYPE_ATTRIBUTES (TREE_TYPE (current_function_decl));
  bool all = lookup_attribute ("saveall", attrs) != NULL_TREE;
  tree kspisusp = lookup_attribute ("kspisusp", attrs);

  if (kspisusp)
    {
      insn = emit_move_insn (spreg, gen_rtx_REG (Pmode, REG_USP));
      RTX_FRAME_RELATED_P (insn) = 1;
    }

  /* We need space on the stack in case we need to save the argument
     registers.  */
  if (fkind == EXCPT_HANDLER)
    {
      insn = emit_insn (gen_addsi3 (spreg, spreg, GEN_INT (-12)));
      RTX_FRAME_RELATED_P (insn) = 1;
    }

  insn = emit_move_insn (predec, gen_rtx_REG (SImode, REG_ASTAT));
  RTX_FRAME_RELATED_P (insn) = 1;

  /* If we're calling other functions, they won't save their call-clobbered
     registers, so we must save everything here.  */
  if (!current_function_is_leaf)
    all = true;
  expand_prologue_reg_save (spreg, all, true);

  for (i = REG_P7 + 1; i < REG_CC; i++)
    if (all 
	|| regs_ever_live[i]
	|| (!leaf_function_p () && call_used_regs[i]))
      {
	if (i == REG_A0 || i == REG_A1)
	  insn = emit_move_insn (gen_rtx_MEM (PDImode, predec1),
				 gen_rtx_REG (PDImode, i));
	else
	  insn = emit_move_insn (predec, gen_rtx_REG (SImode, i));
	RTX_FRAME_RELATED_P (insn) = 1;
      }

  if (lookup_attribute ("nesting", attrs))
    {
      rtx srcreg = gen_rtx_REG (Pmode, (fkind == EXCPT_HANDLER ? REG_RETX
					: fkind == NMI_HANDLER ? REG_RETN
					: REG_RETI));
      insn = emit_move_insn (predec, srcreg);
      RTX_FRAME_RELATED_P (insn) = 1;
    }

  do_link (spreg, frame_size, all);

  if (fkind == EXCPT_HANDLER)
    {
      rtx r0reg = gen_rtx_REG (SImode, REG_R0);
      rtx r1reg = gen_rtx_REG (SImode, REG_R1);
      rtx r2reg = gen_rtx_REG (SImode, REG_R2);
      rtx insn;

      insn = emit_move_insn (r0reg, gen_rtx_REG (SImode, REG_SEQSTAT));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
      insn = emit_insn (gen_ashrsi3 (r0reg, r0reg, GEN_INT (26)));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
      insn = emit_insn (gen_ashlsi3 (r0reg, r0reg, GEN_INT (26)));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
      insn = emit_move_insn (r1reg, spreg);
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
      insn = emit_move_insn (r2reg, gen_rtx_REG (Pmode, REG_FP));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
      insn = emit_insn (gen_addsi3 (r2reg, r2reg, GEN_INT (8)));
      REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx,
					    NULL_RTX);
    }
}

/* Generate an epilogue suitable for a function of kind FKIND.  This is
   called for interrupt and exception handler epilogues.
   SPREG contains (reg:SI REG_SP).  */

static void
expand_interrupt_handler_epilogue (rtx spreg, e_funkind fkind)
{
  int i;
  rtx postinc1 = gen_rtx_POST_INC (SImode, spreg);
  rtx postinc = gen_rtx_MEM (SImode, postinc1);
  tree attrs = TYPE_ATTRIBUTES (TREE_TYPE (current_function_decl));
  bool all = lookup_attribute ("saveall", attrs) != NULL_TREE;

  /* A slightly crude technique to stop flow from trying to delete "dead"
     insns.  */
  MEM_VOLATILE_P (postinc) = 1;

  do_unlink (spreg, get_frame_size (), all);

  if (lookup_attribute ("nesting", attrs))
    {
      rtx srcreg = gen_rtx_REG (Pmode, (fkind == EXCPT_HANDLER ? REG_RETX
					: fkind == NMI_HANDLER ? REG_RETN
					: REG_RETI));
      emit_move_insn (srcreg, postinc);
    }

  /* If we're calling other functions, they won't save their call-clobbered
     registers, so we must save (and restore) everything here.  */
  if (!current_function_is_leaf)
    all = true;

  for (i = REG_CC - 1; i > REG_P7; i--)
    if (all
	|| regs_ever_live[i]
	|| (!leaf_function_p () && call_used_regs[i]))
      {
	if (i == REG_A0 || i == REG_A1)
	  {
	    rtx mem = gen_rtx_MEM (PDImode, postinc1);
	    MEM_VOLATILE_P (mem) = 1;
	    emit_move_insn (gen_rtx_REG (PDImode, i), mem);
	  }
	else
	  emit_move_insn (gen_rtx_REG (SImode, i), postinc);
      }

  expand_epilogue_reg_restore (spreg, all, true);

  emit_move_insn (gen_rtx_REG (SImode, REG_ASTAT), postinc);

  /* Deallocate any space we left on the stack in case we needed to save the
     argument registers.  */
  if (fkind == EXCPT_HANDLER)
    emit_insn (gen_addsi3 (spreg, spreg, GEN_INT (12)));

  emit_jump_insn (gen_return_internal (GEN_INT (fkind)));
}

/* Used while emitting the prologue to generate code to load the correct value
   into the PIC register, which is passed in DEST.  */

static rtx
bfin_load_pic_reg (rtx dest)
{
  struct cgraph_local_info *i = NULL;
  rtx addr, insn;
 
  if (flag_unit_at_a_time)
    i = cgraph_local_info (current_function_decl);
 
  /* Functions local to the translation unit don't need to reload the
     pic reg, since the caller always passes a usable one.  */
  if (i && i->local)
    return pic_offset_table_rtx;
      
  if (bfin_lib_id_given)
    addr = plus_constant (pic_offset_table_rtx, -4 - bfin_library_id * 4);
  else
    addr = gen_rtx_PLUS (Pmode, pic_offset_table_rtx,
			 gen_rtx_UNSPEC (Pmode, gen_rtvec (1, const0_rtx),
					 UNSPEC_LIBRARY_OFFSET));
  insn = emit_insn (gen_movsi (dest, gen_rtx_MEM (Pmode, addr)));
  REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx, NULL);
  return dest;
}

/* Generate RTL for the prologue of the current function.  */

void
bfin_expand_prologue (void)
{
  rtx insn;
  HOST_WIDE_INT frame_size = get_frame_size ();
  rtx spreg = gen_rtx_REG (Pmode, REG_SP);
  e_funkind fkind = funkind (TREE_TYPE (current_function_decl));
  rtx pic_reg_loaded = NULL_RTX;

  if (fkind != SUBROUTINE)
    {
      expand_interrupt_handler_prologue (spreg, fkind);
      return;
    }

  if (current_function_limit_stack)
    {
      HOST_WIDE_INT offset
	= bfin_initial_elimination_offset (ARG_POINTER_REGNUM,
					   STACK_POINTER_REGNUM);
      rtx lim = stack_limit_rtx;

      if (GET_CODE (lim) == SYMBOL_REF)
	{
	  rtx p2reg = gen_rtx_REG (Pmode, REG_P2);
	  if (TARGET_ID_SHARED_LIBRARY)
	    {
	      rtx p1reg = gen_rtx_REG (Pmode, REG_P1);
	      rtx val;
	      pic_reg_loaded = bfin_load_pic_reg (p2reg);
	      val = legitimize_pic_address (stack_limit_rtx, p1reg,
					    pic_reg_loaded);
	      emit_move_insn (p1reg, val);
	      frame_related_constant_load (p2reg, offset, FALSE);
	      emit_insn (gen_addsi3 (p2reg, p2reg, p1reg));
	      lim = p2reg;
	    }
	  else
	    {
	      rtx limit = plus_constant (stack_limit_rtx, offset);
	      emit_move_insn (p2reg, limit);
	      lim = p2reg;
	    }
	}
      emit_insn (gen_compare_lt (bfin_cc_rtx, spreg, lim));
      emit_insn (gen_trapifcc ());
    }
  expand_prologue_reg_save (spreg, 0, false);

  do_link (spreg, frame_size, false);

  if (TARGET_ID_SHARED_LIBRARY
      && (current_function_uses_pic_offset_table
	  || !current_function_is_leaf))
    bfin_load_pic_reg (pic_offset_table_rtx);
}

/* Generate RTL for the epilogue of the current function.  NEED_RETURN is zero
   if this is for a sibcall.  EH_RETURN is nonzero if we're expanding an
   eh_return pattern.  */

void
bfin_expand_epilogue (int need_return, int eh_return)
{
  rtx spreg = gen_rtx_REG (Pmode, REG_SP);
  e_funkind fkind = funkind (TREE_TYPE (current_function_decl));

  if (fkind != SUBROUTINE)
    {
      expand_interrupt_handler_epilogue (spreg, fkind);
      return;
    }