m68k.c

gcc-2.95.3 Linux下最常用的C编译器

/* Subroutines for insn-output.c for Motorola 68000 family.
   Copyright (C) 1987, 93-98, 1999 Free Software Foundation, Inc.

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.  */


/* Some output-actions in m68k.md need these.  */
#include "config.h"
#include "system.h"
#include "tree.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-flags.h"
#include "output.h"
#include "insn-attr.h"
#include "recog.h"
#include "toplev.h"

/* Needed for use_return_insn.  */
#include "flags.h"

#ifdef SUPPORT_SUN_FPA

/* Index into this array by (register number >> 3) to find the
   smallest class which contains that register.  */
enum reg_class regno_reg_class[]
  = { DATA_REGS, ADDR_REGS, FP_REGS,
      LO_FPA_REGS, LO_FPA_REGS, FPA_REGS, FPA_REGS };

#endif /* defined SUPPORT_SUN_FPA */

/* This flag is used to communicate between movhi and ASM_OUTPUT_CASE_END,
   if SGS_SWITCH_TABLE.  */
int switch_table_difference_label_flag;

static rtx find_addr_reg ();
rtx legitimize_pic_address ();


/* Alignment to use for loops and jumps */
/* Specify power of two alignment used for loops. */
const char *m68k_align_loops_string;
/* Specify power of two alignment used for non-loop jumps. */
const char *m68k_align_jumps_string;
/* Specify power of two alignment used for functions. */
const char *m68k_align_funcs_string;

/* Specify power of two alignment used for loops. */
int m68k_align_loops;
/* Specify power of two alignment used for non-loop jumps. */
int m68k_align_jumps;
/* Specify power of two alignment used for functions. */
int m68k_align_funcs;

/* Nonzero if the last compare/test insn had FP operands.  The
   sCC expanders peek at this to determine what to do for the
   68060, which has no fsCC instructions.  */
int m68k_last_compare_had_fp_operands;

/* Sometimes certain combinations of command options do not make
   sense on a particular target machine.  You can define a macro
   `OVERRIDE_OPTIONS' to take account of this.  This macro, if
   defined, is executed once just after all the command options have
   been parsed.

   Don't use this macro to turn on various extra optimizations for
   `-O'.  That is what `OPTIMIZATION_OPTIONS' is for.  */

void
override_options ()
{
  int def_align;

  def_align = 1;

  /* Validate -malign-loops= value, or provide default */
  if (m68k_align_loops_string)
    {
      m68k_align_loops = atoi (m68k_align_loops_string);
      if (m68k_align_loops < 1 || m68k_align_loops > MAX_CODE_ALIGN)
	fatal ("-malign-loops=%d is not between 1 and %d",
	       m68k_align_loops, MAX_CODE_ALIGN);
    }
  else
    m68k_align_loops = def_align;

  /* Validate -malign-jumps= value, or provide default */
  if (m68k_align_jumps_string)
    {
      m68k_align_jumps = atoi (m68k_align_jumps_string);
      if (m68k_align_jumps < 1 || m68k_align_jumps > MAX_CODE_ALIGN)
	fatal ("-malign-jumps=%d is not between 1 and %d",
	       m68k_align_jumps, MAX_CODE_ALIGN);
    }
  else
    m68k_align_jumps = def_align;

  /* Validate -malign-functions= value, or provide default */
  if (m68k_align_funcs_string)
    {
      m68k_align_funcs = atoi (m68k_align_funcs_string);
      if (m68k_align_funcs < 1 || m68k_align_funcs > MAX_CODE_ALIGN)
	fatal ("-malign-functions=%d is not between 1 and %d",
	       m68k_align_funcs, MAX_CODE_ALIGN);
    }
  else
    m68k_align_funcs = def_align;
}

/* This function generates the assembly code for function entry.
   STREAM is a stdio stream to output the code to.
   SIZE is an int: how many units of temporary storage to allocate.
   Refer to the array `regs_ever_live' to determine which registers
   to save; `regs_ever_live[I]' is nonzero if register number I
   is ever used in the function.  This function is responsible for
   knowing which registers should not be saved even if used.  */


/* Note that the order of the bit mask for fmovem is the opposite
   of the order for movem!  */


void
output_function_prologue (stream, size)
     FILE *stream;
     int size;
{
  register int regno;
  register int mask = 0;
  int num_saved_regs = 0;
  extern char call_used_regs[];
  int fsize = (size + 3) & -4;
  int cfa_offset = INCOMING_FRAME_SP_OFFSET, cfa_store_offset = cfa_offset;
  

  if (frame_pointer_needed)
    {
      if (fsize == 0 && TARGET_68040)
	{
	/* on the 68040, pea + move is faster than link.w 0 */
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tpea (%s)\n\tmove.l %s,%s\n",
	       reg_names[FRAME_POINTER_REGNUM], reg_names[STACK_POINTER_REGNUM],
	       reg_names[FRAME_POINTER_REGNUM]);
#else
	  asm_fprintf (stream, "\tpea %s@\n\tmovel %s,%s\n",
	       reg_names[FRAME_POINTER_REGNUM], reg_names[STACK_POINTER_REGNUM],
	       reg_names[FRAME_POINTER_REGNUM]);
#endif
	}
      else if (fsize < 0x8000)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tlink.w %s,%0I%d\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#else
	  asm_fprintf (stream, "\tlink %s,%0I%d\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#endif
	}
      else if (TARGET_68020)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tlink.l %s,%0I%d\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#else
	  asm_fprintf (stream, "\tlink %s,%0I%d\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#endif
	}
      else
	{
      /* Adding negative number is faster on the 68040.  */
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tlink.w %s,%0I0\n\tadd.l %0I%d,%Rsp\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#else
	  asm_fprintf (stream, "\tlink %s,%0I0\n\taddl %0I%d,%Rsp\n",
		       reg_names[FRAME_POINTER_REGNUM], -fsize);
#endif
	}
      if (dwarf2out_do_frame ())
	{
	  char *l;
          l = (char *) dwarf2out_cfi_label ();   
	  cfa_store_offset += 4;
	  cfa_offset = cfa_store_offset;
	  dwarf2out_def_cfa (l, FRAME_POINTER_REGNUM, cfa_offset);
	  dwarf2out_reg_save (l, FRAME_POINTER_REGNUM, -cfa_store_offset);
	  cfa_store_offset += fsize;
	}
    }
  else if (fsize)
    {
      if (fsize + 4 < 0x8000)
	{
#ifndef NO_ADDSUB_Q
	  if (fsize + 4 <= 8)
	    {
	      if (!TARGET_5200)
		{
		  /* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
		  asm_fprintf (stream, "\tsubq.w %0I%d,%Rsp\n", fsize + 4);
#else
		  asm_fprintf (stream, "\tsubqw %0I%d,%Rsp\n", fsize + 4);
#endif
		}
	      else
		{
		  /* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
		  asm_fprintf (stream, "\tsubq.l %0I%d,%Rsp\n", fsize + 4);
#else
		  asm_fprintf (stream, "\tsubql %0I%d,%Rsp\n", fsize + 4);
#endif
		}
	    }
	  else if (fsize + 4 <= 16 && TARGET_CPU32)
	    {
	      /* On the CPU32 it is faster to use two subqw instructions to
		 subtract a small integer (8 < N <= 16) to a register. */
	      /* asm_fprintf() cannot handle %. */
#ifdef MOTOROLA
	      asm_fprintf (stream, "\tsubq.w %0I8,%Rsp\n\tsubq.w %0I%d,%Rsp\n",
			   fsize + 4 - 8);
#else
	      asm_fprintf (stream, "\tsubqw %0I8,%Rsp\n\tsubqw %0I%d,%Rsp\n",
			   fsize + 4 - 8);
#endif
	    }
	  else 
#endif /* not NO_ADDSUB_Q */
	  if (TARGET_68040)
	    {
	      /* Adding negative number is faster on the 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 (dwarf2out_do_frame ())
	{
	  cfa_store_offset += fsize;
	  cfa_offset = cfa_store_offset;
	  dwarf2out_def_cfa ("", STACK_POINTER_REGNUM, cfa_offset);
	}
    }
#ifdef SUPPORT_SUN_FPA
  for (regno = 24; regno < 56; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      {
#ifdef MOTOROLA
	asm_fprintf (stream, "\tfpmovd %s,-(%Rsp)\n",
		     reg_names[regno]);
#else
	asm_fprintf (stream, "\tfpmoved %s,%Rsp@-\n",
		     reg_names[regno]);
#endif
	if (dwarf2out_do_frame ())
	  {
	    char *l = dwarf2out_cfi_label ();

	    cfa_store_offset += 8;
	    if (! frame_pointer_needed)
	      {
		cfa_offset = cfa_store_offset;
		dwarf2out_def_cfa (l, STACK_POINTER_REGNUM, cfa_offset);
	      }
	    dwarf2out_reg_save (l, regno, -cfa_store_offset);
	  }
      }
#endif
  if (TARGET_68881)
    {
      for (regno = 16; regno < 24; regno++)
	if (regs_ever_live[regno] && ! call_used_regs[regno])
	  {
	    mask |= 1 << (regno - 16);
	    num_saved_regs++;
	  }
      if ((mask & 0xff) != 0)
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tfmovm %0I0x%x,-(%Rsp)\n", mask & 0xff);
#else
	  asm_fprintf (stream, "\tfmovem %0I0x%x,%Rsp@-\n", mask & 0xff);
#endif
	  if (dwarf2out_do_frame ())
	    {
	      char *l = (char *) dwarf2out_cfi_label ();
	      int n_regs;

	      cfa_store_offset += num_saved_regs * 12;
	      if (! frame_pointer_needed)
		{
		  cfa_offset = cfa_store_offset;
		  dwarf2out_def_cfa (l, STACK_POINTER_REGNUM, cfa_offset);
		}
	      for (regno = 16, n_regs = 0; regno < 24; regno++)
		if (mask & (1 << (regno - 16)))
		  dwarf2out_reg_save (l, regno,
				      -cfa_store_offset + n_regs++ * 12);
	    }
	}
      mask = 0;
      num_saved_regs = 0;
    }
  for (regno = 0; regno < 16; regno++)
    if (regs_ever_live[regno] && ! call_used_regs[regno])
      {
        mask |= 1 << (15 - regno);
        num_saved_regs++;
      }
  if (frame_pointer_needed)
    {
      mask &= ~ (1 << (15 - FRAME_POINTER_REGNUM));
      num_saved_regs--;
    }
  if (flag_pic && regs_ever_live[PIC_OFFSET_TABLE_REGNUM])
    {
      mask |= 1 << (15 - PIC_OFFSET_TABLE_REGNUM);
      num_saved_regs++;
    }

#if NEED_PROBE
#ifdef MOTOROLA
#ifdef CRDS
  asm_fprintf (stream, "\ttstl %d(%Rsp)\n", NEED_PROBE - num_saved_regs * 4);
#else
  asm_fprintf (stream, "\ttst.l %d(%Rsp)\n", NEED_PROBE - num_saved_regs * 4);
#endif
#else
  asm_fprintf (stream, "\ttstl %Rsp@(%d)\n", NEED_PROBE - num_saved_regs * 4);
#endif
#endif

  if (num_saved_regs <= 2)
    {
      /* Store each separately in the same order moveml uses.
         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))
	  {
	    asm_fprintf (stream,
#ifdef MOTOROLA
			 "\t%Omove.l %s,-(%Rsp)\n",
#else
			 "\tmovel %s,%Rsp@-\n",
#endif
			 reg_names[15 - i]);
	    if (dwarf2out_do_frame ())
	      {
		char *l = (char *) dwarf2out_cfi_label ();

		cfa_store_offset += 4;
 		if (! frame_pointer_needed)
 		  {
 		    cfa_offset = cfa_store_offset;
 		    dwarf2out_def_cfa (l, STACK_POINTER_REGNUM, cfa_offset);
 		  }
 		dwarf2out_reg_save (l, 15 - i, -cfa_store_offset);
	      }
	  }
    }
  else if (mask)
    {
      if (TARGET_5200)
	{
	  /* The coldfire does not support the predecrement form of the 
	     movml instruction, so we must adjust the stack pointer and
	     then use the plain address register indirect mode.  We also
	     have to invert the register save mask to use the new mode.

	     FIXME: if num_saved_regs was calculated earlier, we could
	     combine the stack pointer adjustment with any adjustment
	     done when the initial stack frame is created.  This would
	     save an instruction */
	     
	  int newmask = 0;
	  int i;

	  for (i = 0; i < 16; i++)
	    if (mask & (1 << i))
		newmask |= (1 << (15-i));

#ifdef MOTOROLA
	  asm_fprintf (stream, "\tlea (%d,%Rsp),%Rsp\n", -num_saved_regs*4);
	  asm_fprintf (stream, "\tmovm.l %0I0x%x,(%Rsp)\n", newmask);
#else
	  asm_fprintf (stream, "\tlea %Rsp@(%d),%Rsp\n", -num_saved_regs*4);
	  asm_fprintf (stream, "\tmoveml %0I0x%x,%Rsp@\n", newmask);
#endif
	}
      else
	{
#ifdef MOTOROLA
	  asm_fprintf (stream, "\tmovm.l %0I0x%x,-(%Rsp)\n", mask);
#else
	  asm_fprintf (stream, "\tmoveml %0I0x%x,%Rsp@-\n", mask);
#endif
	}
      if (dwarf2out_do_frame ())
	{
	  char *l = (char *) dwarf2out_cfi_label ();
	  int n_regs;

	  cfa_store_offset += num_saved_regs * 4;
	  if (! frame_pointer_needed)
	    {
	      cfa_offset = cfa_store_offset;
	      dwarf2out_def_cfa (l, STACK_POINTER_REGNUM, cfa_offset);
	    }
	  for (regno = 0, n_regs = 0; regno < 16; regno++)
	    if (mask & (1 << (15 - regno)))
	      dwarf2out_reg_save (l, regno,
				  -cfa_store_offset + n_regs++ * 4);
	}
    }
  if (flag_pic && current_function_uses_pic_offset_table)
    {
#ifdef MOTOROLA
      asm_fprintf (stream, "\t%Olea (%Rpc, %U_GLOBAL_OFFSET_TABLE_@GOTPC), %s\n",
		   reg_names[PIC_OFFSET_TABLE_REGNUM]);
#else
      asm_fprintf (stream, "\tmovel %0I__GLOBAL_OFFSET_TABLE_, %s\n",