sh.c

GCC编译器源代码

}

/* Find the last barrier from insn FROM which is close enough to hold the
   constant pool.  If we can't find one, then create one near the end of
   the range.  */

static rtx
find_barrier (num_mova, mova, from)
     int num_mova;
     rtx mova, from;
{
  int count_si = 0;
  int count_hi = 0;
  int found_hi = 0;
  int found_si = 0;
  int leading_mova = num_mova;
  rtx barrier_before_mova, found_barrier = 0, good_barrier = 0;
  int si_limit;
  int hi_limit;

  /* For HImode: range is 510, add 4 because pc counts from address of
     second instruction after this one, subtract 2 for the jump instruction
     that we may need to emit before the table, subtract 2 for the instruction
     that fills the jump delay slot (in very rare cases, reorg will take an
     instruction from after the constant pool or will leave the delay slot
     empty).  This gives 510.
     For SImode: range is 1020, add 4 because pc counts from address of
     second instruction after this one, subtract 2 in case pc is 2 byte
     aligned, subtract 2 for the jump instruction that we may need to emit
     before the table, subtract 2 for the instruction that fills the jump
     delay slot.  This gives 1018.  */

  /* The branch will always be shortened now that the reference address for
     forward branches is the successor address, thus we need no longer make
     adjustments to the [sh]i_limit for -O0.  */

  si_limit = 1018;
  hi_limit = 510;

  while (from && count_si < si_limit && count_hi < hi_limit)
    {
      int inc = 0;

      /* The instructions created by fixup_addr_diff_vecs have no valid length
       info yet.  They should be considered to have zero at this point.  */
      if (INSN_UID (from) < max_uid_before_fixup_addr_diff_vecs)
	inc = get_attr_length (from);

      if (GET_CODE (from) == BARRIER)
	{
	  found_barrier = from;
	  /* If we are at the end of the function, or in front of an alignment
	     instruction, we need not insert an extra alignment.  We prefer
	     this kind of barrier.  */
	
	  if (cache_align_p (next_real_insn (found_barrier)))
	    good_barrier = from;
	}

      if (broken_move (from))
	{
	  rtx pat, src, dst;
	  enum machine_mode mode;

	  pat = PATTERN (from);
	  if (GET_CODE (pat) == PARALLEL)
	    pat = XVECEXP (pat, 0, 0);
	  src = SET_SRC (pat);
	  dst = SET_DEST (pat);
	  mode = GET_MODE (dst);

	  /* We must explicitly check the mode, because sometimes the
	     front end will generate code to load unsigned constants into
	     HImode targets without properly sign extending them.  */
	  if (mode == HImode || (mode == SImode && hi_const (src)))
	    {
	      found_hi += 2;
	      /* We put the short constants before the long constants, so
		 we must count the length of short constants in the range
		 for the long constants.  */
	      /* ??? This isn't optimal, but is easy to do.  */
	      si_limit -= 2;
	    }
	  else
	    {
	      if (found_si > count_si)
		count_si = found_si;
	      found_si += GET_MODE_SIZE (mode);
	      if (num_mova)
		si_limit -= GET_MODE_SIZE (mode);
	    }
	}

      if (GET_CODE (from) == INSN
	  && GET_CODE (PATTERN (from)) == SET
	  && GET_CODE (SET_SRC (PATTERN (from))) == UNSPEC
	  && XINT (SET_SRC (PATTERN (from)), 1) == 1)
	{
	  if (! num_mova++)
	    {
	      leading_mova = 0;
	      mova = from;
	      barrier_before_mova = good_barrier ? good_barrier : found_barrier;
	    }
	  if (found_si > count_si)
	    count_si = found_si;
	}
      else if (GET_CODE (from) == JUMP_INSN
	       && (GET_CODE (PATTERN (from)) == ADDR_VEC
		   || GET_CODE (PATTERN (from)) == ADDR_DIFF_VEC))
	{
	  if (num_mova)
	    num_mova--;
	  if (cache_align_p (NEXT_INSN (next_nonnote_insn (from))))
	    {
	      /* We have just passed the barrier in front front of the
		 ADDR_DIFF_VEC.  Since the ADDR_DIFF_VEC is accessed
		 as data, just like our pool constants, this is a good
		 opportunity to accommodate what we have gathered so far.
		 If we waited any longer, we could end up at a barrier in
		 front of code, which gives worse cache usage for separated
		 instruction / data caches.  */
	      good_barrier = found_barrier;
	      break;
	    }
	}

      if (found_si)
	count_si += inc;
      if (found_hi)
	count_hi += inc;
      from = NEXT_INSN (from);
    }

  if (num_mova)
    if (leading_mova)
      {
	/* Try as we might, the leading mova is out of range.  Change
	   it into a load (which will become a pcload) and retry.  */
	SET_SRC (PATTERN (mova)) = XVECEXP (SET_SRC (PATTERN (mova)), 0, 0);
	INSN_CODE (mova) = -1;
        return find_barrier (0, 0, mova);
      }
    else
      {
	/* Insert the constant pool table before the mova instruction,
	   to prevent the mova label reference from going out of range.  */
	from = mova;
	good_barrier = found_barrier = barrier_before_mova;
      }

  if (found_barrier)
    {
      /* We have before prepared barriers to come in pairs, with an
	 alignment instruction in-between.  We want to use the first
	 barrier, so that the alignment applies to the code.
	 If we are compiling for SH3 or newer, there are some exceptions
	 when the second barrier and the alignment doesn't exist yet, so
	 we have to add it.  */
      if (good_barrier)
	found_barrier = good_barrier;
      else if (! TARGET_SMALLCODE)
	{
	  found_barrier
	    = emit_insn_before (gen_align_log (GEN_INT (CACHE_LOG)),
				found_barrier);
	  found_barrier = emit_barrier_before (found_barrier);
	}
    }
  else
    {
      /* We didn't find a barrier in time to dump our stuff,
	 so we'll make one.  */
      rtx label = gen_label_rtx ();

      /* If we exceeded the range, then we must back up over the last
	 instruction we looked at.  Otherwise, we just need to undo the
	 NEXT_INSN at the end of the loop.  */
      if (count_hi > hi_limit || count_si > si_limit)
	from = PREV_INSN (PREV_INSN (from));
      else
	from = PREV_INSN (from);

      /* Walk back to be just before any jump or label.
	 Putting it before a label reduces the number of times the branch
	 around the constant pool table will be hit.  Putting it before
	 a jump makes it more likely that the bra delay slot will be
	 filled.  */
      while (GET_CODE (from) == JUMP_INSN || GET_CODE (from) == NOTE
	     || GET_CODE (from) == CODE_LABEL)
	from = PREV_INSN (from);

      from = emit_jump_insn_after (gen_jump (label), from);
      JUMP_LABEL (from) = label;
      LABEL_NUSES (label) = 1;
      found_barrier = emit_barrier_after (from);
      emit_label_after (label, found_barrier);
      if (! TARGET_SMALLCODE)
	{
	  emit_barrier_after (found_barrier);
	  emit_insn_after (gen_align_log (GEN_INT (CACHE_LOG)), found_barrier);
	}
    }

  return found_barrier;
}

/* If the instruction INSN is implemented by a special function, and we can
   positively find the register that is used to call the sfunc, and this
   register is not used anywhere else in this instruction - except as the
   destination of a set, return this register; else, return 0.  */
rtx
sfunc_uses_reg (insn)
     rtx insn;
{
  int i;
  rtx pattern, part, reg_part, reg;

  if (GET_CODE (insn) != INSN)
    return 0;
  pattern = PATTERN (insn);
  if (GET_CODE (pattern) != PARALLEL || get_attr_type (insn) != TYPE_SFUNC)
    return 0;

  for (reg_part = 0, i = XVECLEN (pattern, 0) - 1; i >= 1; i--)
    {
      part = XVECEXP (pattern, 0, i);
      if (GET_CODE (part) == USE && GET_MODE (XEXP (part, 0)) == SImode)
	reg_part = part;
    }
  if (! reg_part)
    return 0;
  reg = XEXP (reg_part, 0);
  for (i = XVECLEN (pattern, 0) - 1; i >= 0; i--)
    {
      part = XVECEXP (pattern, 0, i);
      if (part == reg_part)
	continue;
      if (reg_mentioned_p (reg, ((GET_CODE (part) == SET
				  && GET_CODE (SET_DEST (part)) == REG)
				 ? SET_SRC (part) : part)))
	return 0;
    }
  return reg;
}

/* See if the only way in which INSN uses REG is by calling it, or by
   setting it while calling it.  Set *SET to a SET rtx if the register
   is set by INSN.  */

static int
noncall_uses_reg (reg, insn, set)
     rtx reg;
     rtx insn;
     rtx *set;
{
  rtx pattern, reg2;

  *set = NULL_RTX;

  reg2 = sfunc_uses_reg (insn);
  if (reg2 && REGNO (reg2) == REGNO (reg))
    {
      pattern = single_set (insn);
      if (pattern
	  && GET_CODE (SET_DEST (pattern)) == REG
	  && REGNO (reg) == REGNO (SET_DEST (pattern)))
	*set = pattern;
      return 0;
    }
  if (GET_CODE (insn) != CALL_INSN)
    {
      /* We don't use rtx_equal_p because we don't care if the mode is
	 different.  */
      pattern = single_set (insn);
      if (pattern
	  && GET_CODE (SET_DEST (pattern)) == REG
	  && REGNO (reg) == REGNO (SET_DEST (pattern)))
	{
	  rtx par, part;
	  int i;

	  *set = pattern;
	  par = PATTERN (insn);
	  if (GET_CODE (par) == PARALLEL)
	    for (i = XVECLEN (par, 0) - 1; i >= 0; i--)
	      {
		part = XVECEXP (par, 0, i);
		if (GET_CODE (part) != SET && reg_mentioned_p (reg, part))
		  return 1;
	      }
	  return reg_mentioned_p (reg, SET_SRC (pattern));
	}

      return 1;
    }

  pattern = PATTERN (insn);

  if (GET_CODE (pattern) == PARALLEL)
    {
      int i;

      for (i = XVECLEN (pattern, 0) - 1; i >= 1; i--)
	if (reg_mentioned_p (reg, XVECEXP (pattern, 0, i)))
	  return 1;
      pattern = XVECEXP (pattern, 0, 0);
    }

  if (GET_CODE (pattern) == SET)
    {
      if (reg_mentioned_p (reg, SET_DEST (pattern)))
	{
	  /* We don't use rtx_equal_p, because we don't care if the
             mode is different.  */
	  if (GET_CODE (SET_DEST (pattern)) != REG
	      || REGNO (reg) != REGNO (SET_DEST (pattern)))
	    return 1;

	  *set = pattern;
	}

      pattern = SET_SRC (pattern);
    }

  if (GET_CODE (pattern) != CALL
      || GET_CODE (XEXP (pattern, 0)) != MEM
      || ! rtx_equal_p (reg, XEXP (XEXP (pattern, 0), 0)))
    return 1;

  return 0;
}

/* Given a X, a pattern of an insn or a part of it, return a mask of used
   general registers.  Bits 0..15 mean that the respective registers
   are used as inputs in the instruction.  Bits 16..31 mean that the
   registers 0..15, respectively, are used as outputs, or are clobbered.
   IS_DEST should be set to 16 if X is the destination of a SET, else to 0.  */
int
regs_used (x, is_dest)
     rtx x; int is_dest;
{
  enum rtx_code code;
  char *fmt;
  int i, used = 0;

  if (! x)
    return used;
  code = GET_CODE (x);
  switch (code)
    {
    case REG:
      if (REGNO (x) < 16)
	return (((1 << HARD_REGNO_NREGS (0, GET_MODE (x))) - 1)
		<< (REGNO (x) + is_dest));
      return 0;
    case SUBREG:
      {
	rtx y = SUBREG_REG (x);
     
	if (GET_CODE (y) != REG)
	  break;
	if (REGNO (y) < 16)
	  return (((1 << HARD_REGNO_NREGS (0, GET_MODE (x))) - 1)
		  << (REGNO (y) + SUBREG_WORD (x) + is_dest));
	return 0;
      }
    case SET:
      return regs_used (SET_SRC (x), 0) | regs_used (SET_DEST (x), 16);
    case RETURN:
      /* If there was a return value, it must have been indicated with USE.  */
      return 0x00ffff00;
    case CLOBBER:
      is_dest = 1;
      break;
    case MEM:
      is_dest = 0;
      break;
    case CALL:
      used |= 0x00ff00f0;
      break;
    }

  fmt = GET_RTX_FORMAT (code);

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'E')
	{
	  register int j;
	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
	    used |= regs_used (XVECEXP (x, i, j), is_dest);
	}
      else if (fmt[i] == 'e')
	used |= regs_used (XEXP (x, i), is_dest);
    }
  return used;
}

/* Create an instruction that prevents redirection of a conditional branch
   to the destination of the JUMP with address ADDR.
   If the branch needs to be implemented as an indirect jump, try to find
   a scratch register for it.
   If NEED_BLOCK is 0, don't do anything unless we need a scratch register.
   If any preceding insn that doesn't fit into a delay slot is good enough,
   pass 1.  Pass 2 if a definite blocking insn is needed.
   -1 is used internally to avoid deep recursion.
   If a blocking instruction is made or recognized, return it.  */
   
static rtx
gen_block_redirect (jump, addr, need_block)
     rtx jump;
     int addr, need_block;
{
  int dead = 0;
  rtx prev = prev_nonnote_insn (jump);
  rtx dest;

  /* First, check if we already have an instruction that satisfies our need.  */
  if (prev && GET_CODE (prev) == INSN && ! INSN_DELETED_P (prev))
    {
      if (INSN_CODE (prev) == CODE_FOR_indirect_jump_scratch)
	return prev;
      if (GET_CODE (PATTERN (prev)) == USE
	  || GET_CODE (PATTERN (prev)) == CLOBBER
	  || get_attr_in_delay_slot (prev) == IN_DELAY_SLOT_YES)
	prev = jump;
      else if ((need_block &= ~1) < 0)
	return prev;
      else if (recog_memoized (prev) == CODE_FOR_block_branch_redirect)
	need_block = 0;
    }
  /* We can't use JUMP_LABEL here because it might be undefined
     when not optimizing.  */
  dest = XEXP (SET_SRC (PATTERN (jump)), 0);
  /* If the branch is out of range, try to find a scratch register for it.  */
  if (optimize
      && (insn_addresses[INSN_UID (dest)] - addr + 4092U > 4092 + 4098))
    {
      rtx scan;
      /* Don't look for the stack pointer as a scratch register,
	 it would cause trouble if an interrupt occurred.  */
      unsigned try = 0x7fff, used;
      int jump_left = flag_expensive_optimizations + 1;
    
      /* It is likely that the most recent eligible instruction is wanted for
	 the delay slot.  Therefore, find out which registers it uses, and
	 try to avoid using them.  */
	 
      for (scan = jump; scan = PREV_INSN (scan); )
	{
	  enum rtx_code code;

	  if (INSN_DELETED_P (scan))
	    continue;
	  code = GET_CODE (scan);
	  if (code == CODE_LABEL || code == JUMP_INSN)
	    break;
	  if (code == INSN
	      && GET_CODE (PATTERN (scan)) != USE
	      && GET_CODE (PATTERN (scan)) != CLOBBER
	      && get_attr_in_delay_slot (scan) == IN_DELAY_SLOT_YES)
	    {
	      try &= ~regs_used (PATTERN (scan), 0);
	      break;
	    }
	}
      for (used = dead = 0, scan =