i960.c

GUN开源阻止下的编译器GCC

  if (get_frame_size () != 0)
    leaf_proc_ok = 0;

  /* I don't understand this condition, and do not think that it is correct.
     Apparently this is just checking whether the frame pointer is used, and
     we can't trust regs_ever_live[fp] since it is (almost?) always set.  */

  if (tail_call_ok)
    for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
      if (GET_CODE (insn) == INSN
	  && reg_mentioned_p (frame_pointer_rtx, insn))
	{
	  tail_call_ok = 0;
	  break;
	}

  /* Check for CALL insns.  Can not be a leaf routine if there are any.  */

  if (leaf_proc_ok)
    for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
      if (GET_CODE (insn) == CALL_INSN)
	{
	  leaf_proc_ok = 0;
	  break;
	}

  /* Can not be a leaf routine if any non-call clobbered registers are
     used in this function.  */

  if (leaf_proc_ok)
    for (i = 0, j = 0; i < FIRST_PSEUDO_REGISTER; i++)
      if (regs_ever_live[i]
	  && ((! call_used_regs[i]) || (i > 7 && i < 12)))
	{
	  /* Global registers.  */
	  if (i < 16 && i > 7 && i != 13)
	    leaf_proc_ok = 0;
	  /* Local registers.  */
	  else if (i < 32)
	    leaf_proc_ok = 0;
	}

  /* Now choose a leaf return register, if we can find one, and if it is
     OK for this to be a leaf routine.  */

  i960_leaf_ret_reg = -1;

  if (optimize && leaf_proc_ok)
    {
      for (i960_leaf_ret_reg = -1, i = 0; i < 8; i++)
	if (regs_ever_live[i] == 0)
	  {
	    i960_leaf_ret_reg = i;
	    regs_ever_live[i] = 1;
	    break;
	  }
    }

  /* Do this after choosing the leaf return register, so it will be listed
     if one was chosen.  */

  fprintf (file, "\t#  Function '%s'\n", (name[0] == '*' ? &name[1] : name));
  fprintf (file, "\t#  Registers used: ");

  for (i = 0, j = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      if (regs_ever_live[i])
	{
	  fprintf (file, "%s%s ", reg_names[i], call_used_regs[i] ? "" : "*");

	  if (i > 15 && j == 0)
	    {
	      fprintf (file,"\n\t#\t\t   ");
	      j++;
            }
        }
    }

  fprintf (file, "\n");

  if (i960_leaf_ret_reg >= 0)
    {
      /* Make it a leaf procedure.  */

      if (TREE_PUBLIC (fndecl))
	fprintf (file,"\t.globl\t%s.lf\n", (name[0] == '*' ? &name[1] : name));

      fprintf (file, "\t.leafproc\t");
      assemble_name (file, name);
      fprintf (file, ",%s.lf\n", (name[0] == '*' ? &name[1] : name));
      ASM_OUTPUT_LABEL (file, name);
      fprintf (file, "\tlda    LR%d,g14\n", ret_label);
      fprintf (file, "%s.lf:\n", (name[0] == '*' ? &name[1] : name));
      fprintf (file, "\tmov    g14,g%d\n", i960_leaf_ret_reg);

      if (TARGET_C_SERIES)
	{
	  fprintf (file, "\tlda    0,g14\n");
	  i960_last_insn_type = I_TYPE_MEM;
	}
      else
	{
	  fprintf (file, "\tmov    0,g14\n");
	  i960_last_insn_type = I_TYPE_REG;
	}
    }
  else
    {
      ASM_OUTPUT_LABEL (file, name);
      i960_last_insn_type = I_TYPE_CTRL; 
    }
}

/* Compute and return the frame size.  */

int
compute_frame_size (size)
     int size;
{
  int actual_fsize;
  int outgoing_args_size = current_function_outgoing_args_size;

  /* The STARTING_FRAME_OFFSET is totally hidden to us as far
     as size is concerned.  */
  actual_fsize = (size + 15) & -16;
  actual_fsize += (outgoing_args_size + 15) & -16;

  return actual_fsize;
}

/* Output code for the function prologue.  */

void
i960_function_prologue (file, size)
     FILE *file;
     unsigned int size;
{
  register int i, j, nr;
  int n_iregs = 0;
  int rsize = 0;
  int actual_fsize, offset;
  char tmpstr[1000];
  /* -1 if reg must be saved on proc entry, 0 if available, 1 if saved
     somewhere.  */
  int regs[FIRST_PSEUDO_REGISTER];

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    if (regs_ever_live[i]
	&& ((! call_used_regs[i]) || (i > 7 && i < 12)))
      {
	regs[i] = -1;
        /* Count global registers that need saving.  */
	if (i < 16)
	  n_iregs++;
      }
    else
      regs[i] = 0;

  epilogue_string[0] = '\0';

  if (profile_flag || profile_block_flag)
    {
      /* When profiling, we may use registers 20 to 27 to save arguments, so
	 they can't be used here for saving globals.  J is the number of
	 argument registers the mcount call will save.  */
      for (j = 7; j >= 0 && ! regs_ever_live[j]; j--)
	;

      for (i = 20; i <= j + 20; i++)
	regs[i] = -1;
    }

  /* First look for local registers to save globals in.  */
  for (i = 0; i < 16; i++)
    {
      if (regs[i] == 0)
	continue;

      /* Start at r4, not r3.  */
      for (j = 20; j < 32; j++)
	{
	  if (regs[j] != 0)
	    continue;

	  regs[i] = 1;
	  regs[j] = -1;
	  regs_ever_live[j] = 1;
	  nr = 1;
	  if (i <= 14 && i % 2 == 0 && j <= 30 && j % 2 == 0
	      && regs[i+1] != 0 && regs[j+1] == 0)
	    {
	      nr = 2;
	      regs[i+1] = 1;
	      regs[j+1] = -1;
	      regs_ever_live[j+1] = 1;
	    }
	  if (nr == 2 && i <= 12 && i % 4 == 0 && j <= 28 && j % 4 == 0
	      && regs[i+2] != 0 && regs[j+2] == 0)
	    {
	      nr = 3;
	      regs[i+2] = 1;
	      regs[j+2] = -1;
	      regs_ever_live[j+2] = 1;
	    }
	  if (nr == 3 && regs[i+3] != 0 && regs[j+3] == 0)
	    {
	      nr = 4;
	      regs[i+3] = 1;
	      regs[j+3] = -1;
	      regs_ever_live[j+3] = 1;
	    }

	  fprintf (file, "\tmov%s	%s,%s\n",
		   ((nr == 4) ? "q" :
		    (nr == 3) ? "t" :
		    (nr == 2) ? "l" : ""),
		   reg_names[i], reg_names[j]);
	  sprintf (tmpstr, "\tmov%s	%s,%s\n",
		   ((nr == 4) ? "q" :
		    (nr == 3) ? "t" :
		    (nr == 2) ? "l" : ""),
		   reg_names[j], reg_names[i]);
	  strcat (epilogue_string, tmpstr);

	  n_iregs -= nr;
	  i += nr-1;
	  break;
	}
    }

  /* N_iregs is now the number of global registers that haven't been saved
     yet.  */

  rsize = (n_iregs * 4);
  actual_fsize = compute_frame_size (size) + rsize;
#if 0
  /* ??? The 1.2.1 compiler does this also.  This is meant to round the frame
     size up to the nearest multiple of 16.  I don't know whether this is
     necessary, or even desirable.

     The frame pointer must be aligned, but the call instruction takes care of
     that.  If we leave the stack pointer unaligned, we may save a little on
     dynamic stack allocation.  And we don't lose, at least according to the
     i960CA manual.  */
  actual_fsize = (actual_fsize + 15) & ~0xF;
#endif

  /* Allocate space for register save and locals.  */
  if (actual_fsize > 0)
    {
      if (actual_fsize < 32)
	fprintf (file, "\taddo	%d,sp,sp\n", actual_fsize);
      else
	fprintf (file, "\tlda\t%d(sp),sp\n", actual_fsize);
    }

  /* Take hardware register save area created by the call instruction
     into account, but store them before the argument block area.  */
  offset = 64 + actual_fsize - compute_frame_size (0) - rsize;
  /* Save registers on stack if needed.  */
  for (i = 0, j = n_iregs; j > 0 && i < 16; i++)
    {
      if (regs[i] != -1)
	continue;

      nr = 1;

      if (i <= 14 && i % 2 == 0 && regs[i+1] == -1 && offset % 2 == 0)
	nr = 2;

      if (nr == 2 && i <= 12 && i % 4 == 0 && regs[i+2] == -1
	  && offset % 4 == 0)
	nr = 3;

      if (nr == 3 && regs[i+3] == -1)
	nr = 4;

      fprintf (file,"\tst%s	%s,%d(fp)\n",
	       ((nr == 4) ? "q" :
		(nr == 3) ? "t" :
		(nr == 2) ? "l" : ""),
	       reg_names[i], offset);
      sprintf (tmpstr,"\tld%s	%d(fp),%s\n",
	       ((nr == 4) ? "q" :
		(nr == 3) ? "t" :
		(nr == 2) ? "l" : ""),
	       offset, reg_names[i]);
      strcat (epilogue_string, tmpstr);
      i += nr-1;
      j -= nr;
      offset += nr * 4;
    }

  if (actual_fsize == 0 && size == 0 && rsize == 0)
    return;

  fprintf (file, "\t#Prologue stats:\n");
  fprintf (file, "\t#  Total Frame Size: %d bytes\n", actual_fsize);

  if (size)
    fprintf (file, "\t#  Local Variable Size: %d bytes\n", size);
  if (rsize)
    fprintf (file, "\t#  Register Save Size: %d regs, %d bytes\n",
	     n_iregs, rsize);
  fprintf (file, "\t#End Prologue#\n");
}

/* Output code for the function profiler.  */

void
output_function_profiler (file, labelno)
     FILE *file;
     int labelno;
{
  /* The last used parameter register.  */
  int last_parm_reg;
  int i, j, increment;
  int varargs_stdarg_function
    = VARARGS_STDARG_FUNCTION (current_function_decl);

  /* Figure out the last used parameter register.  The proper thing to do
     is to walk incoming args of the function.  A function might have live
     parameter registers even if it has no incoming args.  Note that we
     don't have to save parameter registers g8 to g11 because they are
     call preserved.  */

  /* See also output_function_prologue, which tries to use local registers
     for preserved call-saved global registers.  */

  for (last_parm_reg = 7;
       last_parm_reg >= 0 && ! regs_ever_live[last_parm_reg];
       last_parm_reg--)
    ;

  /* Save parameter registers in regs r4 (20) to r11 (27).  */

  for (i = 0, j = 4; i <= last_parm_reg; i += increment, j += increment)
    {
      if (i % 4 == 0 && (last_parm_reg - i) >= 3)
	increment = 4;
      else if (i % 4 == 0 && (last_parm_reg - i) >= 2)
	increment = 3;
      else if (i % 2 == 0 && (last_parm_reg - i) >= 1)
	increment = 2;
      else
	increment = 1;

      fprintf (file, "\tmov%s	g%d,r%d\n",
	       (increment == 4 ? "q" : increment == 3 ? "t"
		: increment == 2 ? "l": ""), i, j);
      }

  /* If this function uses the arg pointer, then save it in r3 and then
     set it to zero.  */

  if (current_function_args_size != 0 || varargs_stdarg_function)
    fprintf (file, "\tmov	g14,r3\n\tmov	0,g14\n");

  /* Load location address into g0 and call mcount.  */

  fprintf (file, "\tlda\tLP%d,g0\n\tcallx\tmcount\n", labelno);

  /* If this function uses the arg pointer, restore it.  */

  if (current_function_args_size != 0 || varargs_stdarg_function)
    fprintf (file, "\tmov	r3,g14\n");

  /* Restore parameter registers.  */

  for (i = 0, j = 4; i <= last_parm_reg; i += increment, j += increment)
    {
      if (i % 4 == 0 && (last_parm_reg - i) >= 3)
	increment = 4;
      else if (i % 4 == 0 && (last_parm_reg - i) >= 2)
	increment = 3;
      else if (i % 2 == 0 && (last_parm_reg - i) >= 1)
	increment = 2;
      else
	increment = 1;

      fprintf (file, "\tmov%s	r%d,g%d\n",
	       (increment == 4 ? "q" : increment == 3 ? "t"
		: increment == 2 ? "l": ""), j, i);
    }
}

/* Output code for the function epilogue.  */

void
i960_function_epilogue (file, size)
     FILE *file;
     unsigned int size;
{
  if (i960_leaf_ret_reg >= 0)
    {
      fprintf (file, "LR%d:	ret\n", ret_label);
      return;
    }

  if (*epilogue_string == 0)
    {
      register rtx tmp;
	
      /* Emit a return insn, but only if control can fall through to here.  */

      tmp = get_last_insn ();
      while (tmp)
	{
	  if (GET_CODE (tmp) == BARRIER)
	    return;
	  if (GET_CODE (tmp) == CODE_LABEL)
	    break;
	  if (GET_CODE (tmp) == JUMP_INSN)
	    {
	      if (GET_CODE (PATTERN (tmp)) == RETURN)
		return;
	      break;
	    }
	  if (GET_CODE (tmp) == NOTE)
	    {
	      tmp = PREV_INSN (tmp);
	      continue;
	    }
	  break;
	}
      fprintf (file, "LR%d:	ret\n", ret_label);
      return;
    }

  fprintf (file, "LR%d:\n", ret_label);

  fprintf (file, "\t#EPILOGUE#\n");

  /* Output the string created by the prologue which will restore all
     registers saved by the prologue.  */

  if (epilogue_string[0] != '\0')
    fprintf (file, "%s", epilogue_string);

  /* Must clear g14 on return if this function set it.
     Only varargs/stdarg functions modify g14.  */

  if (VARARGS_STDARG_FUNCTION (current_function_decl))
    fprintf (file, "\tmov	0,g14\n");

  fprintf (file, "\tret\n");
  fprintf (file, "\t#End Epilogue#\n");
}

/* Output code for a call insn.  */

char *
i960_output_call_insn (target, argsize_rtx, arg_pointer, insn)
     register rtx target, argsize_rtx, arg_pointer, insn;
{
  int argsize = INTVAL (argsize_rtx);
  rtx nexti = next_real_insn (insn);
  rtx operands[2];
  int varargs_stdarg_function
    = VARARGS_STDARG_FUNCTION (current_function_decl);

  operands[0] = target;
  operands[1] = arg_pointer;

  if (current_function_args_size != 0 || varargs_stdarg_function)
    output_asm_insn ("mov	g14,r3", operands);

  if (argsize > 48)
    output_asm_insn ("lda	%a1,g14", operands);
  else if (current_function_args_size != 0 || varargs_stdarg_function)
    output_asm_insn ("mov	0,g14", operands);

  /* The code used to assume that calls to SYMBOL_REFs could not be more
     than 24 bits away (b vs bx, callj vs callx).  This is not true.  This
     feature is now implemented by relaxing in the GNU linker.  It can convert
     bx to b if in range, and callx to calls/call/balx/bal as appropriate.  */

  /* Nexti could be zero if the called routine is volatile.  */
  if (optimize && (*epilogue_string == 0) && argsize == 0 && tail_call_ok 
      && (nexti == 0 || GET_CODE (PATTERN (nexti)) == RETURN))
    {
      /* Delete following return insn.  */
      if (nexti && no_labels_between_p (insn, nexti))
	delete_insn (nexti);
      output_asm_insn ("bx	%0", operands);
      return "# notreached";
    }

  output_asm_insn ("callx	%0", operands);

  /* If the caller sets g14 to the address of the argblock, then the caller
     must clear it after the return.  */

  if (current_function_args_size != 0 || varargs_stdarg_function)
    output_asm_insn ("mov	r3,g14", operands);
  else if (argsize > 48)
    output_asm_insn ("mov	0,g14", operands);

  return "";
}

/* Output code for a return insn.  */

char *
i960_output_ret_insn (insn)
     register rtx insn;
{
  static char lbuf[20];
  
  if (*epilogue_string != 0)
    {
      if (! TARGET_CODE_ALIGN && next_real_insn (insn) == 0)
	return "";