fr30.c

linux下的gcc编译器

/* FR30 specific functions.
   Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   Contributed by Cygnus Solutions.

   This file is part of GNU CC.

   GNU CC is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GNU CC is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU CC; see the file COPYING.  If not, write to
   the Free Software Foundation, 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/*{{{  Includes */ 

#include "config.h"
#include "system.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-attr.h"
#include "flags.h"
#include "recog.h"
#include "tree.h"
#include "output.h"
#include "expr.h"
#include "obstack.h"
#include "except.h"
#include "function.h"
#include "tm_p.h"
#include "target.h"
#include "target-def.h"

/*}}}*/
/*{{{  Function Prologues & Epilogues */ 

/* Define the information needed to generate branch and scc insns.  This is
   stored from the compare operation.  */

struct rtx_def * fr30_compare_op0;
struct rtx_def * fr30_compare_op1;

/* The FR30 stack looks like this:

             Before call                       After call
   FP ->|                       |       |                       |
        +-----------------------+       +-----------------------+       high 
        |                       |       |                       |       memory
        |  local variables,     |       |  local variables,     |
        |  reg save area, etc.  |       |  reg save area, etc.  |
        |                       |       |                       |
        +-----------------------+       +-----------------------+
        |                       |       |                       |
        | args to the func that |       |  args to this func.   |
        | is being called that  |       |                       |
   SP ->| do not fit in regs    |       |                       |
        +-----------------------+       +-----------------------+
                                        |  args that used to be |  \
                                        | in regs; only created |   |  pretend_size 
                                   AP-> |   for vararg funcs    |  /  
                                        +-----------------------+    
                                        |                       |  \  
                                        |  register save area   |   |
                                        |                       |   |
					+-----------------------+   |  reg_size
                                        |    return address     |   | 
					+-----------------------+   |
                                   FP ->|   previous frame ptr  |  /
                                        +-----------------------+    
                                        |                       |  \   
                                        |  local variables      |   |  var_size 
                                        |                       |  /  
                                        +-----------------------+    
                                        |                       |  \       
     low                                |  room for args to     |   |
     memory                             |  other funcs called   |   |  args_size     
                                        |  from this one        |   |
                                   SP ->|                       |  /  
                                        +-----------------------+    
   
   Note, AP is a fake hard register.  It will be eliminated in favor of
   SP or FP as appropriate.

   Note, Some or all of the stack sections above may be omitted if they 
   are not needed.  */

/* Structure to be filled in by fr30_compute_frame_size() with register
   save masks, and offsets for the current function.  */
struct fr30_frame_info
{
  unsigned int total_size;	/* # Bytes that the entire frame takes up. */
  unsigned int pretend_size;	/* # Bytes we push and pretend caller did. */
  unsigned int args_size;	/* # Bytes that outgoing arguments take up. */
  unsigned int reg_size;	/* # Bytes needed to store regs. */
  unsigned int var_size;	/* # Bytes that variables take up. */
  unsigned int frame_size;      /* # Bytes in current frame.  */
  unsigned int gmask;		/* Mask of saved registers. */
  unsigned int save_fp;		/* Nonzero if frame pointer must be saved. */
  unsigned int save_rp;		/* Nonzero if return popinter must be saved. */
  int          initialised;	/* Nonzero if frame size already calculated. */
};

/* Current frame information calculated by fr30_compute_frame_size().  */
static struct fr30_frame_info 	current_frame_info;

/* Zero structure to initialize current_frame_info.  */
static struct fr30_frame_info 	zero_frame_info;

static rtx fr30_pass_by_reference PARAMS ((tree, tree));
static rtx fr30_pass_by_value PARAMS ((tree, tree));

#define FRAME_POINTER_MASK 	(1 << (FRAME_POINTER_REGNUM))
#define RETURN_POINTER_MASK 	(1 << (RETURN_POINTER_REGNUM))

/* Tell prologue and epilogue if register REGNO should be saved / restored.
   The return address and frame pointer are treated separately.
   Don't consider them here.  */
#define MUST_SAVE_REGISTER(regno)      \
  (   (regno) != RETURN_POINTER_REGNUM \
   && (regno) != FRAME_POINTER_REGNUM  \
   &&   regs_ever_live [regno]         \
   && ! call_used_regs [regno]         )

#define MUST_SAVE_FRAME_POINTER	 (regs_ever_live [FRAME_POINTER_REGNUM]  || frame_pointer_needed)
#define MUST_SAVE_RETURN_POINTER (regs_ever_live [RETURN_POINTER_REGNUM] || current_function_profile)

#if UNITS_PER_WORD == 4
#define WORD_ALIGN(SIZE) (((SIZE) + 3) & ~3)
#endif

/* Initialize the GCC target structure.  */
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.hword\t"
#undef TARGET_ASM_ALIGNED_SI_OP
#define TARGET_ASM_ALIGNED_SI_OP "\t.word\t"

struct gcc_target targetm = TARGET_INITIALIZER;

/* Returns the number of bytes offset between FROM_REG and TO_REG
   for the current function.  As a side effect it fills in the 
   current_frame_info structure, if the data is available.  */
unsigned int
fr30_compute_frame_size (from_reg, to_reg)
     int from_reg;
     int to_reg;
{
  int 		regno;
  unsigned int 	return_value;
  unsigned int	var_size;
  unsigned int	args_size;
  unsigned int	pretend_size;
  unsigned int 	reg_size;
  unsigned int 	gmask;

  var_size	= WORD_ALIGN (get_frame_size ());
  args_size	= WORD_ALIGN (current_function_outgoing_args_size);
  pretend_size	= current_function_pretend_args_size;

  reg_size	= 0;
  gmask		= 0;

  /* Calculate space needed for registers.  */
  for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno ++)
    {
      if (MUST_SAVE_REGISTER (regno))
	{
	  reg_size += UNITS_PER_WORD;
	  gmask |= 1 << regno;
	}
    }

  current_frame_info.save_fp = MUST_SAVE_FRAME_POINTER;
  current_frame_info.save_rp = MUST_SAVE_RETURN_POINTER;

  reg_size += (current_frame_info.save_fp + current_frame_info.save_rp)
	       * UNITS_PER_WORD;

  /* Save computed information.  */
  current_frame_info.pretend_size = pretend_size;
  current_frame_info.var_size     = var_size;
  current_frame_info.args_size    = args_size;
  current_frame_info.reg_size	  = reg_size;
  current_frame_info.frame_size   = args_size + var_size;
  current_frame_info.total_size   = args_size + var_size + reg_size + pretend_size;
  current_frame_info.gmask	  = gmask;
  current_frame_info.initialised  = reload_completed;

  /* Calculate the required distance.  */
  return_value = 0;
  
  if (to_reg == STACK_POINTER_REGNUM)
    return_value += args_size + var_size;
  
  if (from_reg == ARG_POINTER_REGNUM)
    return_value += reg_size;

  return return_value;
}

/* Called after register allocation to add any instructions needed for the
   prologue.  Using a prologue insn is favored compared to putting all of the
   instructions in output_function_prologue(), since it allows the scheduler
   to intermix instructions with the saves of the caller saved registers.  In
   some cases, it might be necessary to emit a barrier instruction as the last
   insn to prevent such scheduling.  */

void
fr30_expand_prologue ()
{
  int regno;
  rtx insn;

  if (! current_frame_info.initialised)
    fr30_compute_frame_size (0, 0);

  /* This cases shouldn't happen.  Catch it now.  */
  if (current_frame_info.total_size == 0
      && current_frame_info.gmask)
    abort ();

  /* Allocate space for register arguments if this is a variadic function.  */
  if (current_frame_info.pretend_size)
    {
      int regs_to_save = current_frame_info.pretend_size / UNITS_PER_WORD;
      
      /* Push argument registers into the pretend arg area.  */
      for (regno = FIRST_ARG_REGNUM + FR30_NUM_ARG_REGS; regno --, regs_to_save --;)
        {
	  insn = emit_insn (gen_movsi_push (gen_rtx_REG (Pmode, regno)));
	  RTX_FRAME_RELATED_P (insn) = 1;
	}
    }

  if (current_frame_info.gmask)
    {
      /* Save any needed call-saved regs.  */
      for (regno = STACK_POINTER_REGNUM; regno--;)
	{
	  if ((current_frame_info.gmask & (1 << regno)) != 0)
	    {
	      insn = emit_insn (gen_movsi_push (gen_rtx_REG (Pmode, regno)));
	      RTX_FRAME_RELATED_P (insn) = 1;
	    }
	}
    }

  /* Save return address if necessary.  */
  if (current_frame_info.save_rp)
    {
      insn = emit_insn (gen_movsi_push (gen_rtx_REG (Pmode, 
      						     RETURN_POINTER_REGNUM)));
      RTX_FRAME_RELATED_P (insn) = 1;
    }

  /* Save old frame pointer and create new one, if necessary.  */
  if (current_frame_info.save_fp)
    {
      if (current_frame_info.frame_size < ((1 << 10) - UNITS_PER_WORD))
        {
	  int enter_size = current_frame_info.frame_size + UNITS_PER_WORD;
	  rtx pattern;
	  
	  insn = emit_insn (gen_enter_func (GEN_INT (enter_size)));
          RTX_FRAME_RELATED_P (insn) = 1;
	  
	  pattern = PATTERN (insn);
	  
	  /* Also mark all 3 subexpressions as RTX_FRAME_RELATED_P. */
          if (GET_CODE (pattern) == PARALLEL)
            {
              int x;
              for (x = XVECLEN (pattern, 0); x--;)
		{
		  rtx part = XVECEXP (pattern, 0, x);
		  
		  /* One of the insns in the ENTER pattern updates the
		     frame pointer.  If we do not actually need the frame
		     pointer in this function then this is a side effect
		     rather than a desired effect, so we do not mark that
		     insn as being related to the frame set up.  Doing this
		     allows us to compile the crash66.C test file in the
		     G++ testsuite.  */
		  if (! frame_pointer_needed
		      && GET_CODE (part) == SET
		      && REGNO (SET_DEST (part)) == HARD_FRAME_POINTER_REGNUM)
		    RTX_FRAME_RELATED_P (part) = 0;
		  else
		    RTX_FRAME_RELATED_P (part) = 1;
		}
            }
	}
      else
	{
	  insn = emit_insn (gen_movsi_push (frame_pointer_rtx));
          RTX_FRAME_RELATED_P (insn) = 1;

	  if (frame_pointer_needed)
	    {
	      insn = emit_insn (gen_movsi (frame_pointer_rtx, stack_pointer_rtx));
	      RTX_FRAME_RELATED_P (insn) = 1;
	    }
	}
    }

  /* Allocate the stack frame.  */
  if (current_frame_info.frame_size == 0)
    ; /* Nothing to do.  */
  else if (current_frame_info.save_fp
	   && current_frame_info.frame_size < ((1 << 10) - UNITS_PER_WORD))
    ; /* Nothing to do.  */
  else if (current_frame_info.frame_size <= 512)
    {
      insn = emit_insn (gen_add_to_stack (GEN_INT (- current_frame_info.frame_size)));
      RTX_FRAME_RELATED_P (insn) = 1;
    }
  else
    {
      rtx tmp = gen_rtx_REG (Pmode, PROLOGUE_TMP_REGNUM);
      insn = emit_insn (gen_movsi (tmp, GEN_INT (current_frame_info.frame_size)));
      RTX_FRAME_RELATED_P (insn) = 1;
      insn = emit_insn (gen_subsi3 (stack_pointer_rtx, stack_pointer_rtx, tmp));
      RTX_FRAME_RELATED_P (insn) = 1;
    }

  if (current_function_profile)
    emit_insn (gen_blockage ());
}

/* Called after register allocation to add any instructions needed for the
   epilogue.  Using an epilogue insn is favored compared to putting all of the
   instructions in output_function_epilogue(), since it allows the scheduler
   to intermix instructions with the restores of the caller saved registers.
   In some cases, it might be necessary to emit a barrier instruction as the
   first insn to prevent such scheduling.  */
void
fr30_expand_epilogue ()
{
  int regno;

  /* Perform the inversion operations of the prologue.  */
  if (! current_frame_info.initialised)
    abort ();

  /* Pop local variables and arguments off the stack.
     If frame_pointer_needed is TRUE then the frame pointer register
     has actually been used as a frame pointer, and we can recover
     the stack pointer from it, otherwise we must unwind the stack
     manually.  */
  if (current_frame_info.frame_size > 0)
    {
      if (current_frame_info.save_fp && frame_pointer_needed)
	{
	  emit_insn (gen_leave_func ());
	  current_frame_info.save_fp = 0;
	}
      else if (current_frame_info.frame_size <= 508)
	emit_insn (gen_add_to_stack
		   (GEN_INT (current_frame_info.frame_size)));
      else
	{
	  rtx tmp = gen_rtx_REG (Pmode, PROLOGUE_TMP_REGNUM);
	  emit_insn (gen_movsi (tmp, GEN_INT (current_frame_info.frame_size)));