iq2000.c

Mac OS X 10.4.9 for x86 Source Code gcc 实现源代码

      else (offset) = cfun->machine->gp_sp_offset 
	     + ((UNITS_PER_WORD - (POINTER_SIZE / BITS_PER_UNIT)) 
		* (BYTES_BIG_ENDIAN != 0)); 
    }

  return offset;
}

/* Common code to emit the insns (or to write the instructions to a file)
   to save/restore registers.  
   Other parts of the code assume that IQ2000_TEMP1_REGNUM (aka large_reg)
   is not modified within save_restore_insns.  */

#define BITSET_P(VALUE,BIT) (((VALUE) & (1L << (BIT))) != 0)

/* Emit instructions to load the value (SP + OFFSET) into IQ2000_TEMP2_REGNUM
   and return an rtl expression for the register.  Write the assembly
   instructions directly to FILE if it is not null, otherwise emit them as
   rtl.

   This function is a subroutine of save_restore_insns.  It is used when
   OFFSET is too large to add in a single instruction.  */

static rtx
iq2000_add_large_offset_to_sp (HOST_WIDE_INT offset)
{
  rtx reg = gen_rtx_REG (Pmode, IQ2000_TEMP2_REGNUM);
  rtx offset_rtx = GEN_INT (offset);

  emit_move_insn (reg, offset_rtx);
  emit_insn (gen_addsi3 (reg, reg, stack_pointer_rtx));
  return reg;
}

/* Make INSN frame related and note that it performs the frame-related
   operation DWARF_PATTERN.  */

static void
iq2000_annotate_frame_insn (rtx insn, rtx dwarf_pattern)
{
  RTX_FRAME_RELATED_P (insn) = 1;
  REG_NOTES (insn) = alloc_EXPR_LIST (REG_FRAME_RELATED_EXPR,
				      dwarf_pattern,
				      REG_NOTES (insn));
}

/* Emit a move instruction that stores REG in MEM.  Make the instruction
   frame related and note that it stores REG at (SP + OFFSET).  */

static void
iq2000_emit_frame_related_store (rtx mem, rtx reg, HOST_WIDE_INT offset)
{
  rtx dwarf_address = plus_constant (stack_pointer_rtx, offset);
  rtx dwarf_mem = gen_rtx_MEM (GET_MODE (reg), dwarf_address);

  iq2000_annotate_frame_insn (emit_move_insn (mem, reg),
			    gen_rtx_SET (GET_MODE (reg), dwarf_mem, reg));
}

/* Emit instructions to save/restore registers, as determined by STORE_P.  */

static void
save_restore_insns (int store_p)
{
  long mask = cfun->machine->mask;
  int regno;
  rtx base_reg_rtx;
  HOST_WIDE_INT base_offset;
  HOST_WIDE_INT gp_offset;
  HOST_WIDE_INT end_offset;

  if (frame_pointer_needed
      && ! BITSET_P (mask, HARD_FRAME_POINTER_REGNUM - GP_REG_FIRST))
    abort ();

  if (mask == 0)
    {
      base_reg_rtx = 0, base_offset  = 0;
      return;
    }

  /* Save registers starting from high to low.  The debuggers prefer at least
     the return register be stored at func+4, and also it allows us not to
     need a nop in the epilog if at least one register is reloaded in
     addition to return address.  */

  /* Save GP registers if needed.  */
  /* Pick which pointer to use as a base register.  For small frames, just
     use the stack pointer.  Otherwise, use a temporary register.  Save 2
     cycles if the save area is near the end of a large frame, by reusing
     the constant created in the prologue/epilogue to adjust the stack
     frame.  */

  gp_offset = cfun->machine->gp_sp_offset;
  end_offset
    = gp_offset - (cfun->machine->gp_reg_size
		   - GET_MODE_SIZE (gpr_mode));

  if (gp_offset < 0 || end_offset < 0)
    internal_error
      ("gp_offset (%ld) or end_offset (%ld) is less than zero.",
       (long) gp_offset, (long) end_offset);

  else if (gp_offset < 32768)
    base_reg_rtx = stack_pointer_rtx, base_offset  = 0;
  else
    {
      int regno;
      int reg_save_count = 0;

      for (regno = GP_REG_LAST; regno >= GP_REG_FIRST; regno--)
	if (BITSET_P (mask, regno - GP_REG_FIRST)) reg_save_count += 1;
      base_offset = gp_offset - ((reg_save_count - 1) * 4);
      base_reg_rtx = iq2000_add_large_offset_to_sp (base_offset);
    }

  for (regno = GP_REG_LAST; regno >= GP_REG_FIRST; regno--)
    {
      if (BITSET_P (mask, regno - GP_REG_FIRST))
	{
	  rtx reg_rtx;
	  rtx mem_rtx
	    = gen_rtx_MEM (gpr_mode,
		       gen_rtx_PLUS (Pmode, base_reg_rtx,
				GEN_INT (gp_offset - base_offset)));

	  reg_rtx = gen_rtx_REG (gpr_mode, regno);

	  if (store_p)
	    iq2000_emit_frame_related_store (mem_rtx, reg_rtx, gp_offset);
	  else 
	    {
	      emit_move_insn (reg_rtx, mem_rtx);
	    }
	  gp_offset -= GET_MODE_SIZE (gpr_mode);
	}
    }
}

/* Expand the prologue into a bunch of separate insns.  */

void
iq2000_expand_prologue (void)
{
  int regno;
  HOST_WIDE_INT tsize;
  int last_arg_is_vararg_marker = 0;
  tree fndecl = current_function_decl;
  tree fntype = TREE_TYPE (fndecl);
  tree fnargs = DECL_ARGUMENTS (fndecl);
  rtx next_arg_reg;
  int i;
  tree next_arg;
  tree cur_arg;
  CUMULATIVE_ARGS args_so_far;
  int store_args_on_stack = (iq2000_can_use_return_insn ());

  /* If struct value address is treated as the first argument.  */
  if (aggregate_value_p (DECL_RESULT (fndecl), fndecl)
      && ! current_function_returns_pcc_struct
      && targetm.calls.struct_value_rtx (TREE_TYPE (fndecl), 1) == 0)
    {
      tree type = build_pointer_type (fntype);
      tree function_result_decl = build_decl (PARM_DECL, NULL_TREE, type);

      DECL_ARG_TYPE (function_result_decl) = type;
      TREE_CHAIN (function_result_decl) = fnargs;
      fnargs = function_result_decl;
    }

  /* For arguments passed in registers, find the register number
     of the first argument in the variable part of the argument list,
     otherwise GP_ARG_LAST+1.  Note also if the last argument is
     the varargs special argument, and treat it as part of the
     variable arguments.

     This is only needed if store_args_on_stack is true.  */
  INIT_CUMULATIVE_ARGS (args_so_far, fntype, NULL_RTX, 0, 0);
  regno = GP_ARG_FIRST;

  for (cur_arg = fnargs; cur_arg != 0; cur_arg = next_arg)
    {
      tree passed_type = DECL_ARG_TYPE (cur_arg);
      enum machine_mode passed_mode = TYPE_MODE (passed_type);
      rtx entry_parm;

      if (TREE_ADDRESSABLE (passed_type))
	{
	  passed_type = build_pointer_type (passed_type);
	  passed_mode = Pmode;
	}

      entry_parm = FUNCTION_ARG (args_so_far, passed_mode, passed_type, 1);

      FUNCTION_ARG_ADVANCE (args_so_far, passed_mode, passed_type, 1);
      next_arg = TREE_CHAIN (cur_arg);

      if (entry_parm && store_args_on_stack)
	{
	  if (next_arg == 0
	      && DECL_NAME (cur_arg)
	      && ((0 == strcmp (IDENTIFIER_POINTER (DECL_NAME (cur_arg)),
				"__builtin_va_alist"))
		  || (0 == strcmp (IDENTIFIER_POINTER (DECL_NAME (cur_arg)),
				   "va_alist"))))
	    {
	      last_arg_is_vararg_marker = 1;
	      break;
	    }
	  else
	    {
	      int words;

	      if (GET_CODE (entry_parm) != REG)
	        abort ();

	      /* Passed in a register, so will get homed automatically.  */
	      if (GET_MODE (entry_parm) == BLKmode)
		words = (int_size_in_bytes (passed_type) + 3) / 4;
	      else
		words = (GET_MODE_SIZE (GET_MODE (entry_parm)) + 3) / 4;

	      regno = REGNO (entry_parm) + words - 1;
	    }
	}
      else
	{
	  regno = GP_ARG_LAST+1;
	  break;
	}
    }

  /* In order to pass small structures by value in registers we need to
     shift the value into the high part of the register.
     Function_arg has encoded a PARALLEL rtx, holding a vector of
     adjustments to be made as the next_arg_reg variable, so we split up the
     insns, and emit them separately.  */
  next_arg_reg = FUNCTION_ARG (args_so_far, VOIDmode, void_type_node, 1);
  if (next_arg_reg != 0 && GET_CODE (next_arg_reg) == PARALLEL)
    {
      rtvec adjust = XVEC (next_arg_reg, 0);
      int num = GET_NUM_ELEM (adjust);

      for (i = 0; i < num; i++)
	{
	  rtx insn, pattern;

	  pattern = RTVEC_ELT (adjust, i);
	  if (GET_CODE (pattern) != SET
	      || GET_CODE (SET_SRC (pattern)) != ASHIFT)
	    abort_with_insn (pattern, "Insn is not a shift");
	  PUT_CODE (SET_SRC (pattern), ASHIFTRT);

	  insn = emit_insn (pattern);

	  /* Global life information isn't valid at this point, so we
	     can't check whether these shifts are actually used.  Mark
	     them MAYBE_DEAD so that flow2 will remove them, and not
	     complain about dead code in the prologue.  */
	  REG_NOTES(insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, NULL_RTX,
					       REG_NOTES (insn));
	}
    }

  tsize = compute_frame_size (get_frame_size ());

  /* If this function is a varargs function, store any registers that
     would normally hold arguments ($4 - $7) on the stack.  */
  if (store_args_on_stack
      && ((TYPE_ARG_TYPES (fntype) != 0
	   && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
	       != void_type_node))
	  || last_arg_is_vararg_marker))
    {
      int offset = (regno - GP_ARG_FIRST) * UNITS_PER_WORD;
      rtx ptr = stack_pointer_rtx;

      for (; regno <= GP_ARG_LAST; regno++)
	{
	  if (offset != 0)
	    ptr = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset));
	  emit_move_insn (gen_rtx_MEM (gpr_mode, ptr),
			  gen_rtx_REG (gpr_mode, regno));

	  offset += GET_MODE_SIZE (gpr_mode);
	}
    }

  if (tsize > 0)
    {
      rtx tsize_rtx = GEN_INT (tsize);
      rtx adjustment_rtx, insn, dwarf_pattern;

      if (tsize > 32767)
	{
	  adjustment_rtx = gen_rtx_REG (Pmode, IQ2000_TEMP1_REGNUM);
	  emit_move_insn (adjustment_rtx, tsize_rtx);
	}
      else
	adjustment_rtx = tsize_rtx;

      insn = emit_insn (gen_subsi3 (stack_pointer_rtx, stack_pointer_rtx,
				    adjustment_rtx));

      dwarf_pattern = gen_rtx_SET (Pmode, stack_pointer_rtx,
				   plus_constant (stack_pointer_rtx, -tsize));

      iq2000_annotate_frame_insn (insn, dwarf_pattern);

      save_restore_insns (1);

      if (frame_pointer_needed)
	{
	  rtx insn = 0;

	  insn = emit_insn (gen_movsi (hard_frame_pointer_rtx,
				       stack_pointer_rtx));

	  if (insn)
	    RTX_FRAME_RELATED_P (insn) = 1;
	}
    }

  emit_insn (gen_blockage ());
}

/* Expand the epilogue into a bunch of separate insns.  */

void
iq2000_expand_epilogue (void)
{
  HOST_WIDE_INT tsize = cfun->machine->total_size;
  rtx tsize_rtx = GEN_INT (tsize);
  rtx tmp_rtx = (rtx)0;

  if (iq2000_can_use_return_insn ())
    {
      emit_jump_insn (gen_return ());
      return;
    }

  if (tsize > 32767)
    {
      tmp_rtx = gen_rtx_REG (Pmode, IQ2000_TEMP1_REGNUM);
      emit_move_insn (tmp_rtx, tsize_rtx);
      tsize_rtx = tmp_rtx;
    }

  if (tsize > 0)
    {
      if (frame_pointer_needed)
	{
	  emit_insn (gen_blockage ());

	  emit_insn (gen_movsi (stack_pointer_rtx, hard_frame_pointer_rtx));
	}

      save_restore_insns (0);

      if (current_function_calls_eh_return)
	{
	  rtx eh_ofs = EH_RETURN_STACKADJ_RTX;
	  emit_insn (gen_addsi3 (eh_ofs, eh_ofs, tsize_rtx));
	  tsize_rtx = eh_ofs;
	}

      emit_insn (gen_blockage ());

      if (tsize != 0 || current_function_calls_eh_return)
	{
	  emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx,
				 tsize_rtx));
	}
    }

  if (current_function_calls_eh_return)
    {
      /* Perform the additional bump for __throw.  */
      emit_move_insn (gen_rtx_REG (Pmode, HARD_FRAME_POINTER_REGNUM),
		      stack_pointer_rtx);
      emit_insn (gen_rtx_USE (VOIDmode, gen_rtx_REG (Pmode,
						  HARD_FRAME_POINTER_REGNUM)));
      emit_jump_insn (gen_eh_return_internal ());
    }
  else
      emit_jump_insn (gen_return_internal (gen_rtx_REG (Pmode,
						  GP_REG_FIRST + 31)));
}

void
iq2000_expand_eh_return (rtx address)
{
  HOST_WIDE_INT gp_offset = cfun->machine->gp_sp_offset;
  rtx scratch;

  scratch = plus_constant (stack_pointer_rtx, gp_offset);
  emit_move_insn (gen_rtx_MEM (GET_MODE (address), scratch), address);
}

/* Return nonzero if this function is known to have a null epilogue.
   This allows the optimizer to omit jumps to jumps if no stack
   was created.  */

int
iq2000_can_use_return_insn (void)
{
  if (! reload_completed)
    return 0;

  if (regs_ever_live[31] || profile_flag)
    return 0;

  if (cfun->machine->initialized)
    return cfun->machine->total_size == 0;

  return compute_frame_size (get_frame_size ()) == 0;
}

/* Returns nonzero if X contains a SYMBOL_REF.  */

static int
symbolic_expression_p (rtx x)
{
  if (GET_CODE (x) == SYMBOL_REF)
    return 1;

  if (GET_CODE (x) == CONST)
    return symbolic_expression_p (XEXP (x, 0));

  if (UNARY_P (x))
    return symbolic_expression_p (XEXP (x, 0));

  if (ARITHMETIC_P (x))
    return (symbolic_expression_p (XEXP (x, 0))
	    || symbolic_expression_p (XEXP (x, 1)));

  return 0;
}

/* Choose the section to use for the constant rtx expression X that has
   mode MODE.  */

static void
iq2000_select_rtx_section (enum machine_mode mode, rtx x ATTRIBUTE_UNUSED,
			   unsigned HOST_WIDE_INT align)
{
  /* For embedded applications, always put constants in read-only data,
     in order to reduce RAM usage.  */
      /* For embedded applications, always put constants in read-only data,
         in order to reduce RAM usage.  */
  mergeable_constant_section (mode, align, 0);
}

/* Choose the section to use for DECL.  RELOC is true if its value contains
   any relocatable expression.

   Some of the logic used here needs to be replicated in
   ENCODE_SECTION_INFO in iq2000.h so that references to these symbols
   are done correctly.  */

static void
iq2000_select_section (tree decl, int reloc ATTRIBUTE_UNUSED,
		       unsigned HOST_WIDE_INT align ATTRIBUTE_UNUSED)
{
  if (TARGET_EMBEDDED_DATA)
    {
      /* For embedded applications, always put an object in read-only data
	 if possible, in order to reduce RAM usage.  */
      if ((TREE_CODE (decl) == VAR_DECL
	   && TREE_READONLY (decl) && !TREE_SIDE_EFFECTS (decl)
	   && DECL_INITIAL (decl)
	   && (DECL_INITIAL (decl) == error_mark_node
	       || TREE_CONSTANT (DECL_INITIAL (decl))))
	  /* Deal with calls from output_constant_def_contents.  */
	  || TREE_CODE (decl) != VAR_DECL)
	readonly_data_section ();
      else
	data_section ();
    }
  else
    {
      /* For hosted applications, always put an object in small data if
	 possible, as this gives the best performance.  */
      if ((TREE_CODE (decl) == VAR_DECL
	   && TREE_READONLY (decl) && !TREE_SIDE_EFFECTS (decl)
	   && DECL_INITIAL (decl)
	   && (DECL_INITIAL (decl) == error_mark_node
	       || TREE_CONSTANT (DECL_INITIAL (decl))))
	  /* Deal with calls from output_constant_def_contents.  */
	  || TREE_CODE (decl) != VAR_DECL)
	readonly_dat