frv.c

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 * +---------------+-----------------------+-----------------------+
 * |GR0            |Zero register          |        -              |
 * |GR1            |Stack pointer(SP)      |        -              |
 * |GR2            |Frame pointer(FP)      |        -              |
 * |GR3            |Hidden parameter       |        caller save    |
 * |GR4-GR7        |        -              |        caller save    |
 * |GR8-GR13       |Argument register      |        caller save    |
 * |GR14-GR15      |        -              |        caller save    |
 * |GR16-GR31      |        -              |        callee save    |
 * |GR32-GR47      |        -              |        caller save    |
 * |GR48-GR63      |        -              |        callee save    |
 * |FR0-FR15       |        -              |        caller save    |
 * |FR16-FR31      |        -              |        callee save    |
 * |FR32-FR47      |        -              |        caller save    |
 * |FR48-FR63      |        -              |        callee save    |
 * +---------------+-----------------------+-----------------------+
 *
 * Stack frame setup:
 * Low
 *     SP-> |-----------------------------------|
 *	    |         Argument area		|
 *	    |-----------------------------------|
 *	    |	 Register save area		|
 *	    |-----------------------------------|
 *	    |	Local variable save area	|
 *     FP-> |-----------------------------------|
 *	    |	    Old FP			|
 *	    |-----------------------------------|
 *	    |    Hidden parameter save area     |
 *	    |-----------------------------------|
 *	    | Return address(LR) storage area   |
 *	    |-----------------------------------|
 *	    |     Padding for alignment         |
 *	    |-----------------------------------|
 *	    |     Register argument area	|
 * OLD SP-> |-----------------------------------|
 *          |       Parameter area		|
 *          |-----------------------------------|
 * High
 *
 * Argument area/Parameter area:
 *
 * When a function is called, this area is used for argument transfer.  When
 * the argument is set up by the caller function, this area is referred to as
 * the argument area.  When the argument is referenced by the callee function,
 * this area is referred to as the parameter area.  The area is allocated when
 * all arguments cannot be placed on the argument register at the time of
 * argument transfer.
 *
 * Register save area:
 *
 * This is a register save area that must be guaranteed for the caller
 * function.  This area is not secured when the register save operation is not
 * needed.
 *
 * Local variable save area:
 *
 * This is the area for local variables and temporary variables.
 *
 * Old FP:
 *
 * This area stores the FP value of the caller function.
 *
 * Hidden parameter save area:
 *
 * This area stores the start address of the return value storage
 * area for a struct/union return function.
 * When a struct/union is used as the return value, the caller
 * function stores the return value storage area start address in
 * register GR3 and passes it to the caller function.
 * The callee function interprets the address stored in the GR3
 * as the return value storage area start address.
 * When register GR3 needs to be saved into memory, the callee
 * function saves it in the hidden parameter save area.  This
 * area is not secured when the save operation is not needed.
 *
 * Return address(LR) storage area:
 *
 * This area saves the LR.  The LR stores the address of a return to the caller
 * function for the purpose of function calling.
 *
 * Argument register area:
 *
 * This area saves the argument register.  This area is not secured when the
 * save operation is not needed.
 *
 * Argument:
 *
 * Arguments, the count of which equals the count of argument registers (6
 * words), are positioned in registers GR8 to GR13 and delivered to the callee
 * function.  When a struct/union return function is called, the return value
 * area address is stored in register GR3.  Arguments not placed in the
 * argument registers will be stored in the stack argument area for transfer
 * purposes.  When an 8-byte type argument is to be delivered using registers,
 * it is divided into two and placed in two registers for transfer.  When
 * argument registers must be saved to memory, the callee function secures an
 * argument register save area in the stack.  In this case, a continuous
 * argument register save area must be established in the parameter area.  The
 * argument register save area must be allocated as needed to cover the size of
 * the argument register to be saved.  If the function has a variable count of
 * arguments, it saves all argument registers in the argument register save
 * area.
 *
 * Argument Extension Format:
 *
 * When an argument is to be stored in the stack, its type is converted to an
 * extended type in accordance with the individual argument type.  The argument
 * is freed by the caller function after the return from the callee function is
 * made.
 *
 * +-----------------------+---------------+------------------------+
 * |    Argument Type      |Extended Type  |Stack Storage Size(byte)|
 * +-----------------------+---------------+------------------------+
 * |char                   |int            |        4		    |
 * |signed char            |int            |        4		    |
 * |unsigned char          |int            |        4		    |
 * |[signed] short int     |int            |        4		    |
 * |unsigned short int     |int            |        4		    |
 * |[signed] int           |No extension   |        4		    |
 * |unsigned int           |No extension   |        4		    |
 * |[signed] long int      |No extension   |        4		    |
 * |unsigned long int      |No extension   |        4		    |
 * |[signed] long long int |No extension   |        8		    |
 * |unsigned long long int |No extension   |        8		    |
 * |float                  |double         |        8		    |
 * |double                 |No extension   |        8		    |
 * |long double            |No extension   |        8		    |
 * |pointer                |No extension   |        4		    |
 * |struct/union           |-              |        4 (*1)	    |
 * +-----------------------+---------------+------------------------+
 *
 * When a struct/union is to be delivered as an argument, the caller copies it
 * to the local variable area and delivers the address of that area.
 *
 * Return Value:
 *
 * +-------------------------------+----------------------+
 * |Return Value Type              |Return Value Interface|
 * +-------------------------------+----------------------+
 * |void                           |None                  |
 * |[signed|unsigned] char         |GR8                   |
 * |[signed|unsigned] short int    |GR8                   |
 * |[signed|unsigned] int          |GR8                   |
 * |[signed|unsigned] long int     |GR8                   |
 * |pointer                        |GR8                   |
 * |[signed|unsigned] long long int|GR8 & GR9             |
 * |float                          |GR8                   |
 * |double                         |GR8 & GR9             |
 * |long double                    |GR8 & GR9             |
 * |struct/union                   |(*1)                  |
 * +-------------------------------+----------------------+
 *
 * When a struct/union is used as the return value, the caller function stores
 * the start address of the return value storage area into GR3 and then passes
 * it to the callee function.  The callee function interprets GR3 as the start
 * address of the return value storage area.  When this address needs to be
 * saved in memory, the callee function secures the hidden parameter save area
 * and saves the address in that area.
 */

frv_stack_t *
frv_stack_info ()
{
  static frv_stack_t info, zero_info;
  frv_stack_t *info_ptr	= &info;
  tree fndecl		= current_function_decl;
  int varargs_p		= 0;
  tree cur_arg;
  tree next_arg;
  int range;
  int alignment;
  int offset;

  /* If we've already calculated the values and reload is complete, just return now */
  if (frv_stack_cache)
    return frv_stack_cache;

  /* Zero all fields */
  info = zero_info;

  /* Set up the register range information */
  info_ptr->regs[STACK_REGS_GPR].name         = "gpr";
  info_ptr->regs[STACK_REGS_GPR].first        = LAST_ARG_REGNUM + 1;
  info_ptr->regs[STACK_REGS_GPR].last         = GPR_LAST;
  info_ptr->regs[STACK_REGS_GPR].dword_p      = TRUE;

  info_ptr->regs[STACK_REGS_FPR].name         = "fpr";
  info_ptr->regs[STACK_REGS_FPR].first        = FPR_FIRST;
  info_ptr->regs[STACK_REGS_FPR].last         = FPR_LAST;
  info_ptr->regs[STACK_REGS_FPR].dword_p      = TRUE;

  info_ptr->regs[STACK_REGS_LR].name          = "lr";
  info_ptr->regs[STACK_REGS_LR].first         = LR_REGNO;
  info_ptr->regs[STACK_REGS_LR].last          = LR_REGNO;
  info_ptr->regs[STACK_REGS_LR].special_p     = 1;

  info_ptr->regs[STACK_REGS_CC].name          = "cc";
  info_ptr->regs[STACK_REGS_CC].first         = CC_FIRST;
  info_ptr->regs[STACK_REGS_CC].last          = CC_LAST;
  info_ptr->regs[STACK_REGS_CC].field_p       = TRUE;

  info_ptr->regs[STACK_REGS_LCR].name         = "lcr";
  info_ptr->regs[STACK_REGS_LCR].first        = LCR_REGNO;
  info_ptr->regs[STACK_REGS_LCR].last         = LCR_REGNO;

  info_ptr->regs[STACK_REGS_STDARG].name      = "stdarg";
  info_ptr->regs[STACK_REGS_STDARG].first     = FIRST_ARG_REGNUM;
  info_ptr->regs[STACK_REGS_STDARG].last      = LAST_ARG_REGNUM;
  info_ptr->regs[STACK_REGS_STDARG].dword_p   = 1;
  info_ptr->regs[STACK_REGS_STDARG].special_p = 1;

  info_ptr->regs[STACK_REGS_STRUCT].name      = "struct";
  info_ptr->regs[STACK_REGS_STRUCT].first     = STRUCT_VALUE_REGNUM;
  info_ptr->regs[STACK_REGS_STRUCT].last      = STRUCT_VALUE_REGNUM;
  info_ptr->regs[STACK_REGS_STRUCT].special_p = 1;

  info_ptr->regs[STACK_REGS_FP].name          = "fp";
  info_ptr->regs[STACK_REGS_FP].first         = FRAME_POINTER_REGNUM;
  info_ptr->regs[STACK_REGS_FP].last          = FRAME_POINTER_REGNUM;
  info_ptr->regs[STACK_REGS_FP].special_p     = 1;

  /* Determine if this is a stdarg function.  If so, allocate space to store
     the 6 arguments.  */
  if (cfun->stdarg)
    varargs_p = 1;

  else
    {
      /* Find the last argument, and see if it is __builtin_va_alist.  */
      for (cur_arg = DECL_ARGUMENTS (fndecl); cur_arg != (tree)0; cur_arg = next_arg)
	{
	  next_arg = TREE_CHAIN (cur_arg);
	  if (next_arg == (tree)0)
	    {
	      if (DECL_NAME (cur_arg)
		  && !strcmp (IDENTIFIER_POINTER (DECL_NAME (cur_arg)), "__builtin_va_alist"))
		varargs_p = 1;

	      break;
	    }
	}
    }

  /* Iterate over all of the register ranges */
  for (range = 0; range < STACK_REGS_MAX; range++)
    {
      frv_stack_regs_t *reg_ptr = &(info_ptr->regs[range]);
      int first = reg_ptr->first;
      int last = reg_ptr->last;
      int size_1word = 0;
      int size_2words = 0;
      int regno;

      /* Calculate which registers need to be saved & save area size */
      switch (range)
	{
	default:
	  for (regno = first; regno <= last; regno++)
	    {
	      if ((regs_ever_live[regno] && !call_used_regs[regno])
		  || (current_function_calls_eh_return
		      && (regno >= FIRST_EH_REGNUM && regno <= LAST_EH_REGNUM))
		  || (flag_pic && cfun->uses_pic_offset_table && regno == PIC_REGNO))
		{
		  info_ptr->save_p[regno] = REG_SAVE_1WORD;
		  size_1word += UNITS_PER_WORD;
		}
	    }
	  break;

	  /* Calculate whether we need to create a frame after everything else
             has been processed.  */
	case STACK_REGS_FP:
	  break;

	case STACK_REGS_LR:
	  if (regs_ever_live[LR_REGNO]
              || profile_flag
              || frame_pointer_needed
              || (flag_pic && cfun->uses_pic_offset_table))
	    {
	      info_ptr->save_p[LR_REGNO] = REG_SAVE_1WORD;
	      size_1word += UNITS_PER_WORD;
	    }
	  break;

	case STACK_REGS_STDARG:
	  if (varargs_p)
	    {
	      /* If this is a stdarg function with an non varardic argument split
		 between registers and the stack, adjust the saved registers
		 downward */
	      last -= (ADDR_ALIGN (cfun->pretend_args_size, UNITS_PER_WORD)
		       / UNITS_PER_WORD);

	      for (regno = first; regno <= last; regno++)
		{
		  info_ptr->save_p[regno] = REG_SAVE_1WORD;
		  size_1word += UNITS_PER_WORD;
		}

	      info_ptr->stdarg_size = size_1word;
	    }
	  break;

	case STACK_REGS_STRUCT:
	  if (cfun->returns_struct)
	    {
	      info_ptr->save_p[STRUCT_VALUE_REGNUM] = REG_SAVE_1WORD;
	      size_1word += UNITS_PER_WORD;
	    }
	  break;
	}


      if (size_1word)
	{
	  /* If this is a field, it only takes one word */
	  if (reg_ptr->field_p)
	    size_1word = UNITS_PER_WORD;

	  /* Determine which register pairs can be saved together */
	  else if (reg_ptr->dword_p && TARGET_DWORD)
	    {
	      for (regno = first; regno < last; regno += 2)
		{
		  if (info_ptr->save_p[regno] && info_ptr->save_p[regno+1])
		    {
		      size_2words += 2 * UNITS_PER_WORD;
		      size_1word -= 2 * UNITS_PER_WORD;
		      info_ptr->save_p[regno] = REG_SAVE_2WORDS;
		      info_ptr->save_p[regno+1] = REG_SAVE_NO_SAVE;
		    }
		}
	    }

	  reg_ptr->size_1word = size_1word;
	  reg_ptr->size_2words = size_2words;

	  if (! reg_ptr->special_p)
	    {
	      info_ptr->regs_size_1word += size_1word;
	      info_ptr->regs_size_2words += size_2words;
	    }
	}
    }

  /* Set up the sizes of each each field in the frame body, making the sizes
     of each be divisible by the size of a dword if dword operations might
     be used, or the size of a word otherwise.  */
  alignment = (TARGET_DWORD? 2 * UNITS_PER_WORD : UNITS_PER_WORD);

  info_ptr->parameter_size = ADDR_ALIGN (cfun->outgoing_args_size, alignment);
  info_ptr->regs_size = ADDR_ALIGN (info_ptr->regs_size_2words
				    + info_ptr->regs_size_1word,
				    alignment);
  info_ptr->vars_size = ADDR_ALIGN (get_frame_size (), alignment);

  info_ptr->pretend_size = cfun->pretend_args_size;

  /* Work out the size of the frame, excluding the header.  Both the frame
     body and register parameter area will be dword-aligned.  */
  info_ptr->total_size
    = (ADDR_ALIGN (info_ptr->parameter_size
		   + info_ptr->regs_size
		   + info_ptr->vars_size,
		   2 * UNITS_PER_WORD)
       + ADDR_ALIGN (info_ptr->pretend_size
		     + info_ptr->stdarg_size,
		     2 * UNITS_PER_WORD));

  /* See if we need to create a frame at all, if so add header area.  */
  if (info_ptr->total_size  > 0
      || info_ptr->regs[STACK_REGS_LR].size_1word > 0
      || info_ptr->regs[STACK_REGS_STRUCT].size_1word > 0)
    {
      offset = info_ptr->parameter_size;
      info_ptr->header_size = 4 * UNITS_PER_WORD;
      info_ptr->total_size += 4 * UNITS_PER_WORD;

      /* Calculate the offsets to save normal register pairs */
      for (range = 0; range < STACK_REGS_MAX; range++)
	{
	  frv_stack_regs_t *reg_ptr = &(info_ptr->regs[range]);
	  if (! reg_ptr->special_p)
	    {