m68k.c

gcc-2.95.3 Linux下最常用的C编译器

		   reg_names[PIC_OFFSET_TABLE_REGNUM]);
      asm_fprintf (stream, "\tlea %Rpc@(0,%s:l),%s\n",
		   reg_names[PIC_OFFSET_TABLE_REGNUM],
		   reg_names[PIC_OFFSET_TABLE_REGNUM]);
#endif
    }
}

/* Return true if this function's epilogue can be output as RTL.  */

int
use_return_insn ()
{
  int regno;

  if (!reload_completed || frame_pointer_needed || get_frame_size () != 0)
    return 0;
  
  /* Copied from output_function_epilogue ().  We should probably create a
     separate layout routine to perform the common work.  */
  
  for (regno = 0 ; regno < FIRST_PSEUDO_REGISTER ; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      return 0;
  
  return 1;
}

/* This function generates the assembly code for function exit,
   on machines that need it.  Args are same as for FUNCTION_PROLOGUE.

   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.  */

void
output_function_epilogue (stream, size)
     FILE *stream;
     int size;
{
  register int regno;
  register int mask, fmask;
  register int nregs;
  int offset, foffset, fpoffset;
  extern char call_used_regs[];
  int fsize = (size + 3) & -4;
  int big = 0;
  rtx insn = get_last_insn ();
  int restore_from_sp = 0;
  
  /* If the last insn was a BARRIER, we don't have to write any code.  */
  if (GET_CODE (insn) == NOTE)
    insn = prev_nonnote_insn (insn);
  if (insn && GET_CODE (insn) == BARRIER)
    {
      /* Output just a no-op so that debuggers don't get confused
	 about which function the pc is in at this address.  */
      asm_fprintf (stream, "\tnop\n");
      return;
    }

#ifdef FUNCTION_BLOCK_PROFILER_EXIT
  if (profile_block_flag == 2)
    {
      FUNCTION_BLOCK_PROFILER_EXIT (stream);
    }
#endif

#ifdef FUNCTION_EXTRA_EPILOGUE
  FUNCTION_EXTRA_EPILOGUE (stream, size);
#endif
  nregs = 0;  fmask = 0; fpoffset = 0;
#ifdef SUPPORT_SUN_FPA
  for (regno = 24 ; regno < 56 ; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      nregs++;
  fpoffset = nregs * 8;
#endif
  nregs = 0;
  if (TARGET_68881)
    {
      for (regno = 16; regno < 24; regno++)
	if (regs_ever_live[regno] && ! call_used_regs[regno])
	  {
	    nregs++;
	    fmask |= 1 << (23 - regno);
	  }
    }
  foffset = fpoffset + nregs * 12;
  nregs = 0;  mask = 0;
  if (frame_pointer_needed)
    regs_ever_live[FRAME_POINTER_REGNUM] = 0;
  for (regno = 0; regno < 16; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      {
        nregs++;
	mask |= 1 << regno;
      }
  if (flag_pic && regs_ever_live[PIC_OFFSET_TABLE_REGNUM])
    {
      nregs++;
      mask |= 1 << PIC_OFFSET_TABLE_REGNUM;
    }
  offset = foffset + nregs * 4;
  /* FIXME : leaf_function_p below is too strong.
     What we really need to know there is if there could be pending
     stack adjustment needed at that point. */
  restore_from_sp = ! frame_pointer_needed
	     || (! current_function_calls_alloca && leaf_function_p ());
  if (offset + fsize >= 0x8000
      && ! restore_from_sp
      && (mask || fmask || fpoffset))
    {
#ifdef MOTOROLA
      asm_fprintf (stream, "\t%Omove.l %0I%d,%Ra1\n", -fsize);
#else
      asm_fprintf (stream, "\tmovel %0I%d,%Ra1\n", -fsize);
#endif
      fsize = 0, big = 1;
    }
  if (TARGET_5200 || nregs <= 2)
    {
      /* Restore each separately in the same order moveml does.
         Using two movel instructions instead of a single moveml
         is about 15% faster for the 68020 and 68030 at no expense
         in code size. */

      int i;

      /* Undo the work from above. */
      for (i = 0; i< 16; i++)
        if (mask & (1 << i))
          {
            if (big)
	      {
#ifdef MOTOROLA
		asm_fprintf (stream, "\t%Omove.l -%d(%s,%Ra1.l),%s\n",
			     offset + fsize,
			     reg_names[FRAME_POINTER_REGNUM],
			     reg_names[i]);
#else
		asm_fprintf (stream, "\tmovel %s@(-%d,%Ra1:l),%s\n",
			     reg_names[FRAME_POINTER_REGNUM],
			     offset + fsize, reg_names[i]);
#endif
	      }
            else if (restore_from_sp)
	      {
#ifdef MOTOROLA
		asm_fprintf (stream, "\t%Omove.l (%Rsp)+,%s\n",
			     reg_names[i]);
#else
		asm_fprintf (stream, "\tmovel %Rsp@+,%s\n",
			     reg_names[i]);
#endif
	      }
            else
	      {
#ifdef MOTOROLA
		asm_fprintf (stream, "\t%Omove.l -%d(%s),%s\n",
			     offset + fsize,
			     reg_names[FRAME_POINTER_REGNUM],
			     reg_names[i]);
#else
		asm_fprintf (stream, "\tmovel %s@(-%d),%s\n",
			     reg_names[FRAME_POINTER_REGNUM],
			     offset + fsize, reg_names[i]);
#endif
	      }
            offset = offset - 4;
          }
    }
  else if (mask)
    {
      if (big)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tmovm.l -%d(%s,%Ra1.l),%0I0x%x\n",
		       offset + fsize,
		       reg_names[FRAME_POINTER_REGNUM],
		       mask);
#else
	  asm_fprintf (stream, "\tmoveml %s@(-%d,%Ra1:l),%0I0x%x\n",
		       reg_names[FRAME_POINTER_REGNUM],
		       offset + fsize, mask);
#endif
	}
      else if (restore_from_sp)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tmovm.l (%Rsp)+,%0I0x%x\n", mask);
#else
	  asm_fprintf (stream, "\tmoveml %Rsp@+,%0I0x%x\n", mask);
#endif
	}
      else
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tmovm.l -%d(%s),%0I0x%x\n",
		       offset + fsize,
		       reg_names[FRAME_POINTER_REGNUM],
		       mask);
#else
	  asm_fprintf (stream, "\tmoveml %s@(-%d),%0I0x%x\n",
		       reg_names[FRAME_POINTER_REGNUM],
		       offset + fsize, mask);
#endif
	}
    }
  if (fmask)
    {
      if (big)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tfmovm -%d(%s,%Ra1.l),%0I0x%x\n",
		       foffset + fsize,
		       reg_names[FRAME_POINTER_REGNUM],
		       fmask);
#else
	  asm_fprintf (stream, "\tfmovem %s@(-%d,%Ra1:l),%0I0x%x\n",
		       reg_names[FRAME_POINTER_REGNUM],
		       foffset + fsize, fmask);
#endif
	}
      else if (restore_from_sp)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tfmovm (%Rsp)+,%0I0x%x\n", fmask);
#else
	  asm_fprintf (stream, "\tfmovem %Rsp@+,%0I0x%x\n", fmask);
#endif
	}
      else
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tfmovm -%d(%s),%0I0x%x\n",
		       foffset + fsize,
		       reg_names[FRAME_POINTER_REGNUM],
		       fmask);
#else
	  asm_fprintf (stream, "\tfmovem %s@(-%d),%0I0x%x\n",
		       reg_names[FRAME_POINTER_REGNUM],
		       foffset + fsize, fmask);
#endif
	}
    }
  if (fpoffset != 0)
    for (regno = 55; regno >= 24; regno--)
      if (regs_ever_live[regno] && ! call_used_regs[regno])
        {
	  if (big)
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tfpmovd -%d(%s,%Ra1.l), %s\n",
			   fpoffset + fsize,
			   reg_names[FRAME_POINTER_REGNUM],
			   reg_names[regno]);
#else
	      asm_fprintf (stream, "\tfpmoved %s@(-%d,%Ra1:l), %s\n",
			   reg_names[FRAME_POINTER_REGNUM],
			   fpoffset + fsize, reg_names[regno]);
#endif
	    }
	  else if (restore_from_sp)
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tfpmovd (%Rsp)+,%s\n",
			   reg_names[regno]);
#else
	      asm_fprintf (stream, "\tfpmoved %Rsp@+, %s\n",
			   reg_names[regno]);
#endif
	    }
	  else
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tfpmovd -%d(%s), %s\n",
			   fpoffset + fsize,
			   reg_names[FRAME_POINTER_REGNUM],
			   reg_names[regno]);
#else
	      asm_fprintf (stream, "\tfpmoved %s@(-%d), %s\n",
			   reg_names[FRAME_POINTER_REGNUM],
			   fpoffset + fsize, reg_names[regno]);
#endif
	    }
	  fpoffset -= 8;
	}
  if (frame_pointer_needed)
    fprintf (stream, "\tunlk %s\n",
	     reg_names[FRAME_POINTER_REGNUM]);
  else if (fsize)
    {
#ifndef NO_ADDSUB_Q
      if (fsize + 4 <= 8) 
	{
	  if (!TARGET_5200)
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\taddq.w %0I%d,%Rsp\n", fsize + 4);
#else
	      asm_fprintf (stream, "\taddqw %0I%d,%Rsp\n", fsize + 4);
#endif
	    }
	  else
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\taddq.l %0I%d,%Rsp\n", fsize + 4);
#else
	      asm_fprintf (stream, "\taddql %0I%d,%Rsp\n", fsize + 4);
#endif
	    }
	}
      else if (fsize + 4 <= 16 && TARGET_CPU32)
	{
	  /* On the CPU32 it is faster to use two addqw instructions to
	     add a small integer (8 < N <= 16) to a register. */
	  /* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
	  asm_fprintf (stream, "\taddq.w %0I8,%Rsp\n\taddq.w %0I%d,%Rsp\n",
		       fsize + 4 - 8);
#else
	  asm_fprintf (stream, "\taddqw %0I8,%Rsp\n\taddqw %0I%d,%Rsp\n",
		       fsize + 4 - 8);
#endif
	}
      else
#endif /* not NO_ADDSUB_Q */
      if (fsize + 4 < 0x8000)
	{
	  if (TARGET_68040)
	    { 
	      /* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tadd.w %0I%d,%Rsp\n", fsize + 4);
#else
	      asm_fprintf (stream, "\taddw %0I%d,%Rsp\n", fsize + 4);
#endif
	    }
	  else
	    {
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tlea (%d,%Rsp),%Rsp\n", fsize + 4);
#else
	      asm_fprintf (stream, "\tlea %Rsp@(%d),%Rsp\n", fsize + 4);
#endif
	    }
	}
      else
	{
	/* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tadd.l %0I%d,%Rsp\n", fsize + 4);
#else
	  asm_fprintf (stream, "\taddl %0I%d,%Rsp\n", fsize + 4);
#endif
	}
    }
  if (current_function_pops_args)
    asm_fprintf (stream, "\trtd %0I%d\n", current_function_pops_args);
  else
    fprintf (stream, "\trts\n");
}

/* Similar to general_operand, but exclude stack_pointer_rtx.  */

int
not_sp_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return op != stack_pointer_rtx && general_operand (op, mode);
}

/* Return TRUE if X is a valid comparison operator for the dbcc 
   instruction.  

   Note it rejects floating point comparison operators.
   (In the future we could use Fdbcc).

   It also rejects some comparisons when CC_NO_OVERFLOW is set.  */
   
int
valid_dbcc_comparison_p (x, mode)
     rtx x;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  switch (GET_CODE (x))
    {
      case EQ: case NE: case GTU: case LTU:
      case GEU: case LEU:
        return 1;

      /* Reject some when CC_NO_OVERFLOW is set.  This may be over
         conservative */
      case GT: case LT: case GE: case LE:
        return ! (cc_prev_status.flags & CC_NO_OVERFLOW);
      default:
        return 0;
    }
}

/* Return non-zero if flags are currently in the 68881 flag register.  */
int
flags_in_68881 ()
{
  /* We could add support for these in the future */
  return cc_status.flags & CC_IN_68881;
}

/* Output a dbCC; jCC sequence.  Note we do not handle the 
   floating point version of this sequence (Fdbcc).  We also
   do not handle alternative conditions when CC_NO_OVERFLOW is
   set.  It is assumed that valid_dbcc_comparison_p and flags_in_68881 will
   kick those out before we get here.  */

void
output_dbcc_and_branch (operands)
     rtx *operands;
{
  switch (GET_CODE (operands[3]))
    {
      case EQ:
#ifdef MOTOROLA
        output_asm_insn ("dbeq %0,%l1\n\tjbeq %l2", operands);
#else
        output_asm_insn ("dbeq %0,%l1\n\tjeq %l2", operands);
#endif
        break;

      case NE:
#ifdef MOTOROLA
        output_asm_insn ("dbne %0,%l1\n\tjbne %l2", operands);
#else
        output_asm_insn ("dbne %0,%l1\n\tjne %l2", operands);
#endif
        break;

      case GT:
#ifdef MOTOROLA
        output_asm_insn ("dbgt %0,%l1\n\tjbgt %l2", operands);
#else
        output_asm_insn ("dbgt %0,%l1\n\tjgt %l2", operands);
#endif
        break;

      case GTU:
#ifdef MOTOROLA
        output_asm_insn ("dbhi %0,%l1\n\tjbhi %l2", operands);
#else
        output_asm_insn ("dbhi %0,%l1\n\tjhi %l2", operands);
#endif
        break;

      case LT:
#ifdef MOTOROLA
        output_asm_insn ("dblt %0,%l1\n\tjblt %l2", operands);
#else
        output_asm_insn ("dblt %0,%l1\n\tjlt %l2", operands);
#endif
        break;

      case LTU:
#ifdef MOTOROLA
        output_asm_insn ("dbcs %0,%l1\n\tjbcs %l2", operands);
#else
        output_asm_insn ("dbcs %0,%l1\n\tjcs %l2", operands);
#endif
        break;