m68k.c

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/* Subroutines for insn-output.c for Motorola 68000 family.
   Copyright (C) 1987, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003
   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.  */

#include "config.h"
#include "system.h"
#include "tree.h"
#include "rtl.h"
#include "function.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "output.h"
#include "insn-attr.h"
#include "recog.h"
#include "toplev.h"
#include "expr.h"
#include "reload.h"
#include "tm_p.h"
#include "target.h"
#include "target-def.h"
#include "debug.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.  */
const 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 PARAMS ((rtx));
static const char *singlemove_string PARAMS ((rtx *));
static void m68k_output_function_prologue PARAMS ((FILE *, HOST_WIDE_INT));
static void m68k_output_function_epilogue PARAMS ((FILE *, HOST_WIDE_INT));
static void m68k_coff_asm_named_section PARAMS ((const char *, unsigned int));
#ifdef CTOR_LIST_BEGIN
static void m68k_svr3_asm_out_constructor PARAMS ((rtx, int));
#endif
static void m68k_output_mi_thunk PARAMS ((FILE *, tree, HOST_WIDE_INT,
					  HOST_WIDE_INT, tree));
static int m68k_save_reg PARAMS ((unsigned int));


/* 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;

/* Initialize the GCC target structure.  */

#if INT_OP_GROUP == INT_OP_DOT_WORD
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.word\t"
#endif

#if INT_OP_GROUP == INT_OP_NO_DOT
#undef TARGET_ASM_BYTE_OP
#define TARGET_ASM_BYTE_OP "\tbyte\t"
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\tshort\t"
#undef TARGET_ASM_ALIGNED_SI_OP
#define TARGET_ASM_ALIGNED_SI_OP "\tlong\t"
#endif

#if INT_OP_GROUP == INT_OP_DC
#undef TARGET_ASM_BYTE_OP
#define TARGET_ASM_BYTE_OP "\tdc.b\t"
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\tdc.w\t"
#undef TARGET_ASM_ALIGNED_SI_OP
#define TARGET_ASM_ALIGNED_SI_OP "\tdc.l\t"
#endif

#undef TARGET_ASM_UNALIGNED_HI_OP
#define TARGET_ASM_UNALIGNED_HI_OP TARGET_ASM_ALIGNED_HI_OP
#undef TARGET_ASM_UNALIGNED_SI_OP
#define TARGET_ASM_UNALIGNED_SI_OP TARGET_ASM_ALIGNED_SI_OP

#undef TARGET_ASM_FUNCTION_PROLOGUE
#define TARGET_ASM_FUNCTION_PROLOGUE m68k_output_function_prologue
#undef TARGET_ASM_FUNCTION_EPILOGUE
#define TARGET_ASM_FUNCTION_EPILOGUE m68k_output_function_epilogue

#undef TARGET_ASM_OUTPUT_MI_THUNK
#define TARGET_ASM_OUTPUT_MI_THUNK m68k_output_mi_thunk
#undef TARGET_ASM_CAN_OUTPUT_MI_THUNK
#define TARGET_ASM_CAN_OUTPUT_MI_THUNK default_can_output_mi_thunk_no_vcall

struct gcc_target targetm = TARGET_INITIALIZER;

/* 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;
  int i;

  def_align = 1;

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

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

  /* Validate -malign-functions= value, or provide default */
  m68k_align_funcs = def_align;
  if (m68k_align_funcs_string)
    {
      i = atoi (m68k_align_funcs_string);
      if (i < 1 || i > MAX_CODE_ALIGN)
	error ("-malign-functions=%d is not between 1 and %d",
	       i, MAX_CODE_ALIGN);
      else
	m68k_align_funcs = i;
    }

  /* -fPIC uses 32-bit pc-relative displacements, which don't exist
     until the 68020.  */
  if (! TARGET_68020 && flag_pic == 2)
    error("-fPIC is not currently supported on the 68000 or 68010\n");

  /* ??? A historic way of turning on pic, or is this intended to
     be an embedded thing that doesn't have the same name binding
     significance that it does on hosted ELF systems?  */
  if (TARGET_PCREL && flag_pic == 0)
    flag_pic = 1;

  /* Turn off function cse if we are doing PIC.  We always want function call
     to be done as `bsr foo@PLTPC', so it will force the assembler to create
     the PLT entry for `foo'. Doing function cse will cause the address of
     `foo' to be loaded into a register, which is exactly what we want to
     avoid when we are doing PIC on svr4 m68k.  */
  if (flag_pic)
    flag_no_function_cse = 1;

  SUBTARGET_OVERRIDE_OPTIONS;

  /* Tell the compiler which flavor of XFmode we're using.  */
  real_format_for_mode[XFmode - QFmode] = &ieee_extended_motorola_format;
}

/* Return 1 if we need to save REGNO.  */
static int
m68k_save_reg (regno)
     unsigned int regno;
{
  if (flag_pic && current_function_uses_pic_offset_table
      && regno == PIC_OFFSET_TABLE_REGNUM)
    return 1;

  if (current_function_calls_eh_return)
    {
      unsigned int i;
      for (i = 0; ; i++)
	{
	  unsigned int test = EH_RETURN_DATA_REGNO (i);
	  if (test == INVALID_REGNUM)
	    break;
	  if (test == regno)
	    return 1;
	}
    }

  return (regs_ever_live[regno]
	  && !call_used_regs[regno]
	  && !fixed_regs[regno]
	  && !(regno == FRAME_POINTER_REGNUM && frame_pointer_needed));
}

/* 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!  */

#ifdef CRDS

static void
m68k_output_function_prologue (stream, size)
     FILE *stream;
     HOST_WIDE_INT size;
{
  register int regno;
  register int mask = 0;
  HOST_WIDE_INT fsize = ((size) + 3) & -4;

  /* unos stack probe */
  if (fsize > 30000)
    {
      fprintf (stream, "\tmovel sp,a0\n");
      fprintf (stream, "\taddl $-%d,a0\n", 2048 + fsize);
      fprintf (stream, "\ttstb (a0)\n");
    }
  else
    fprintf (stream, "\ttstb -%d(sp)\n", 2048 + fsize);

  if (frame_pointer_needed)
    {
      if (TARGET_68020 || fsize < 0x8000)
	fprintf (stream, "\tlink a6,$%d\n", -fsize);
      else
	fprintf (stream, "\tlink a6,$0\n\tsubl $%d,sp\n", fsize);
    }
  else if (fsize)
    {
      /* Adding negative number is faster on the 68040.  */
      if (fsize + 4 < 0x8000)
	fprintf (stream, "\tadd.w $%d,sp\n", - (fsize + 4));
      else
	fprintf (stream, "\tadd.l $%d,sp\n", - (fsize + 4));
    }

  for (regno = 16; regno < 24; regno++)
    if (m68k_save_reg (regno))
      mask |= 1 << (regno - 16);

  if ((mask & 0xff) != 0)
    fprintf (stream, "\tfmovem $0x%x,-(sp)\n", mask & 0xff);

  mask = 0;
  for (regno = 0; regno < 16; regno++)
    if (m68k_save_reg (regno))
      mask |= 1 << (15 - regno);

  if (exact_log2 (mask) >= 0)
    fprintf (stream, "\tmovel %s,-(sp)\n", reg_names[15 - exact_log2 (mask)]);
  else if (mask)
    fprintf (stream, "\tmovem $0x%x,-(sp)\n", mask);
}

#else  /* !CRDS */

static void
m68k_output_function_prologue (stream, size)
     FILE *stream;
     HOST_WIDE_INT size;
{
  register int regno;
  register int mask = 0;
  int num_saved_regs = 0;
  HOST_WIDE_INT fsize = (size + 3) & -4;
  HOST_WIDE_INT cfa_offset = INCOMING_FRAME_SP_OFFSET;
  HOST_WIDE_INT cfa_store_offset = cfa_offset;
  
  /* If the stack limit is a symbol, we can check it here,
     before actually allocating the space.  */
  if (current_function_limit_stack
      && GET_CODE (stack_limit_rtx) == SYMBOL_REF)
    {
#if defined (MOTOROLA)
      asm_fprintf (stream, "\tcmp.l %0I%s+%d,%Rsp\n\ttrapcs\n",
		   XSTR (stack_limit_rtx, 0), fsize + 4);
#else
      asm_fprintf (stream, "\tcmpl %0I%s+%d,%Rsp\n\ttrapcs\n",
		   XSTR (stack_limit_rtx, 0), fsize + 4);
#endif
    }

  if (frame_pointer_needed)
    {
      if (fsize == 0 && TARGET_68040)
	{
	/* on the 68040, pea + move is faster than link.w 0 */
#ifdef MOTOROLA
	  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
	  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_reg_save (l, FRAME_POINTER_REGNUM, -cfa_store_offset);
	  dwarf2out_def_cfa (l, FRAME_POINTER_REGNUM, cfa_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 + 4;
	  cfa_offset = cfa_store_offset;
	  dwarf2out_def_cfa ("", STACK_POINTER_REGNUM, cfa_offset);
	}
    }
#ifdef SUPPORT_SUN_FPA
  for (regno = 24; regno < 56; regno++)
    if (m68k_save_reg (regno))