m68hc11.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

/* Subroutines for code generation on Motorola 68HC11 and 68HC12.
   Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
   Contributed by Stephane Carrez ([e-mail])

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.

Note:
   A first 68HC11 port was made by Otto Lind ([e-mail])
   on gcc 2.6.3.  I have used it as a starting point for this port.
   However, this new port is a complete re-write.  Its internal
   design is completely different.  The generated code is not
   compatible with the gcc 2.6.3 port.

   The gcc 2.6.3 port is available at:

   ftp.unina.it/pub/electronics/motorola/68hc11/gcc/gcc-6811-fsf.tar.gz

*/

#include <stdio.h>
#include "config.h"
#include "system.h"
#include "rtl.h"
#include "tree.h"
#include "tm_p.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 "flags.h"
#include "recog.h"
#include "expr.h"
#include "toplev.h"
#include "basic-block.h"
#include "function.h"
#include "ggc.h"
#include "reload.h"
#include "target.h"
#include "target-def.h"

static void print_options PARAMS ((FILE *));
static void emit_move_after_reload PARAMS ((rtx, rtx, rtx));
static rtx simplify_logical PARAMS ((enum machine_mode, int, rtx, rtx *));
static void m68hc11_emit_logical PARAMS ((enum machine_mode, int, rtx *));
static int go_if_legitimate_address_internal PARAMS((rtx, enum machine_mode,
                                                     int));
static int register_indirect_p PARAMS((rtx, enum machine_mode, int));
static rtx m68hc11_expand_compare PARAMS((enum rtx_code, rtx, rtx));
static int must_parenthesize PARAMS ((rtx));
static int m68hc11_shift_cost PARAMS ((enum machine_mode, rtx, int));
static int autoinc_mode PARAMS ((rtx));
static int m68hc11_make_autoinc_notes PARAMS ((rtx*, void*));
static int m68hc11_auto_inc_p PARAMS ((rtx));
static tree m68hc11_handle_fntype_attribute PARAMS ((tree *, tree, tree, int, bool *));
const struct attribute_spec m68hc11_attribute_table[];

void create_regs_rtx PARAMS ((void));

static void asm_print_register PARAMS ((FILE *, int));
static void m68hc11_output_function_epilogue PARAMS ((FILE *, HOST_WIDE_INT));
static void m68hc11_asm_out_constructor PARAMS ((rtx, int));
static void m68hc11_asm_out_destructor PARAMS ((rtx, int));
static void m68hc11_encode_section_info PARAMS((tree, int));

/* Must be set to 1 to produce debug messages.  */
int debug_m6811 = 0;

extern FILE *asm_out_file;

rtx ix_reg;
rtx iy_reg;
rtx d_reg;
rtx m68hc11_soft_tmp_reg;
static GTY(()) rtx stack_push_word;
static GTY(()) rtx stack_pop_word;
static GTY(()) rtx z_reg;
static GTY(()) rtx z_reg_qi;
static int regs_inited = 0;

/* Set to 1 by expand_prologue() when the function is an interrupt handler.  */
int current_function_interrupt;

/* Set to 1 by expand_prologue() when the function is a trap handler.  */
int current_function_trap;

/* Set to 1 when the current function is placed in 68HC12 banked
   memory and must return with rtc.  */
int current_function_far;

/* Min offset that is valid for the indirect addressing mode.  */
HOST_WIDE_INT m68hc11_min_offset = 0;

/* Max offset that is valid for the indirect addressing mode.  */
HOST_WIDE_INT m68hc11_max_offset = 256;

/* The class value for base registers.  */
enum reg_class m68hc11_base_reg_class = A_REGS;

/* The class value for index registers.  This is NO_REGS for 68HC11.  */
enum reg_class m68hc11_index_reg_class = NO_REGS;

enum reg_class m68hc11_tmp_regs_class = NO_REGS;

/* Tables that tell whether a given hard register is valid for
   a base or an index register.  It is filled at init time depending
   on the target processor.  */
unsigned char m68hc11_reg_valid_for_base[FIRST_PSEUDO_REGISTER];
unsigned char m68hc11_reg_valid_for_index[FIRST_PSEUDO_REGISTER];

/* A correction offset which is applied to the stack pointer.
   This is 1 for 68HC11 and 0 for 68HC12.  */
int m68hc11_sp_correction;

/* Comparison operands saved by the "tstxx" and "cmpxx" expand patterns.  */
rtx m68hc11_compare_op0;
rtx m68hc11_compare_op1;


const struct processor_costs *m68hc11_cost;

/* Costs for a 68HC11.  */
static const struct processor_costs m6811_cost = {
  /* add */
  COSTS_N_INSNS (2),
  /* logical */
  COSTS_N_INSNS (2),
  /* non-constant shift */
  COSTS_N_INSNS (20),
  /* shiftQI const */
  { COSTS_N_INSNS (0), COSTS_N_INSNS (1), COSTS_N_INSNS (2),
    COSTS_N_INSNS (3), COSTS_N_INSNS (4), COSTS_N_INSNS (3),
    COSTS_N_INSNS (2), COSTS_N_INSNS (1) },

  /* shiftHI const */
  { COSTS_N_INSNS (0), COSTS_N_INSNS (1), COSTS_N_INSNS (4),
    COSTS_N_INSNS (6), COSTS_N_INSNS (8), COSTS_N_INSNS (6),
    COSTS_N_INSNS (4), COSTS_N_INSNS (2),
    COSTS_N_INSNS (2), COSTS_N_INSNS (4),
    COSTS_N_INSNS (6), COSTS_N_INSNS (8), COSTS_N_INSNS (10),
    COSTS_N_INSNS (8), COSTS_N_INSNS (6), COSTS_N_INSNS (4)
  },
  /* mulQI */
  COSTS_N_INSNS (20),
  /* mulHI */
  COSTS_N_INSNS (20 * 4),
  /* mulSI */
  COSTS_N_INSNS (20 * 16),
  /* divQI */
  COSTS_N_INSNS (20),
  /* divHI */
  COSTS_N_INSNS (80),
  /* divSI */
  COSTS_N_INSNS (100)
};

/* Costs for a 68HC12.  */
static const struct processor_costs m6812_cost = {
  /* add */
  COSTS_N_INSNS (2),
  /* logical */
  COSTS_N_INSNS (2),
  /* non-constant shift */
  COSTS_N_INSNS (20),
  /* shiftQI const */
  { COSTS_N_INSNS (0), COSTS_N_INSNS (1), COSTS_N_INSNS (2),
    COSTS_N_INSNS (3), COSTS_N_INSNS (4), COSTS_N_INSNS (3),
    COSTS_N_INSNS (2), COSTS_N_INSNS (1) },

  /* shiftHI const */
  { COSTS_N_INSNS (0), COSTS_N_INSNS (1), COSTS_N_INSNS (4),
    COSTS_N_INSNS (6), COSTS_N_INSNS (8), COSTS_N_INSNS (6),
    COSTS_N_INSNS (4), COSTS_N_INSNS (2),
    COSTS_N_INSNS (2), COSTS_N_INSNS (4), COSTS_N_INSNS (6),
    COSTS_N_INSNS (8), COSTS_N_INSNS (10), COSTS_N_INSNS (8),
    COSTS_N_INSNS (6), COSTS_N_INSNS (4)
  },
  /* mulQI */
  COSTS_N_INSNS (3),
  /* mulHI */
  COSTS_N_INSNS (3),
  /* mulSI */
  COSTS_N_INSNS (3 * 4),
  /* divQI */
  COSTS_N_INSNS (12),
  /* divHI */
  COSTS_N_INSNS (12),
  /* divSI */
  COSTS_N_INSNS (100)
};

/* Machine specific options */

const char *m68hc11_regparm_string;
const char *m68hc11_reg_alloc_order;
const char *m68hc11_soft_reg_count;

static int nb_soft_regs;

/* Initialize the GCC target structure.  */
#undef TARGET_ATTRIBUTE_TABLE
#define TARGET_ATTRIBUTE_TABLE m68hc11_attribute_table

#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.word\t"

#undef TARGET_ASM_FUNCTION_EPILOGUE
#define TARGET_ASM_FUNCTION_EPILOGUE m68hc11_output_function_epilogue

#undef TARGET_ENCODE_SECTION_INFO
#define TARGET_ENCODE_SECTION_INFO  m68hc11_encode_section_info

struct gcc_target targetm = TARGET_INITIALIZER;

int
m68hc11_override_options ()
{
  memset (m68hc11_reg_valid_for_index, 0,
	  sizeof (m68hc11_reg_valid_for_index));
  memset (m68hc11_reg_valid_for_base, 0, sizeof (m68hc11_reg_valid_for_base));

  /* Compilation with -fpic generates a wrong code.  */
  if (flag_pic)
    {
      warning ("-f%s ignored for 68HC11/68HC12 (not supported)",
	       (flag_pic > 1) ? "PIC" : "pic");
      flag_pic = 0;
    }

  /* Configure for a 68hc11 processor.  */
  if (TARGET_M6811)
    {
      /* If gcc was built for a 68hc12, invalidate that because
         a -m68hc11 option was specified on the command line.  */
      if (TARGET_DEFAULT != MASK_M6811)
        target_flags &= ~TARGET_DEFAULT;

      if (!TARGET_M6812)
        target_flags &= ~(TARGET_AUTO_INC_DEC | TARGET_MIN_MAX);
      m68hc11_cost = &m6811_cost;
      m68hc11_min_offset = 0;
      m68hc11_max_offset = 256;
      m68hc11_index_reg_class = NO_REGS;
      m68hc11_base_reg_class = A_REGS;
      m68hc11_reg_valid_for_base[HARD_X_REGNUM] = 1;
      m68hc11_reg_valid_for_base[HARD_Y_REGNUM] = 1;
      m68hc11_reg_valid_for_base[HARD_Z_REGNUM] = 1;
      m68hc11_sp_correction = 1;
      m68hc11_tmp_regs_class = D_REGS;
      if (m68hc11_soft_reg_count == 0 && !TARGET_M6812)
	m68hc11_soft_reg_count = "4";
    }

  /* Configure for a 68hc12 processor.  */
  if (TARGET_M6812)
    {
      m68hc11_cost = &m6812_cost;
      m68hc11_min_offset = -65536;
      m68hc11_max_offset = 65536;
      m68hc11_index_reg_class = D_REGS;
      m68hc11_base_reg_class = A_OR_SP_REGS;
      m68hc11_reg_valid_for_base[HARD_X_REGNUM] = 1;
      m68hc11_reg_valid_for_base[HARD_Y_REGNUM] = 1;
      m68hc11_reg_valid_for_base[HARD_Z_REGNUM] = 1;
      m68hc11_reg_valid_for_base[HARD_SP_REGNUM] = 1;
      m68hc11_reg_valid_for_index[HARD_D_REGNUM] = 1;
      m68hc11_sp_correction = 0;
      m68hc11_tmp_regs_class = TMP_REGS;
      target_flags &= ~MASK_M6811;
      target_flags |= MASK_NO_DIRECT_MODE;
      if (m68hc11_soft_reg_count == 0)
	m68hc11_soft_reg_count = "0";

      if (TARGET_LONG_CALLS)
        current_function_far = 1;
    }
  return 0;
}


void
m68hc11_conditional_register_usage ()
{
  int i;
  int cnt = atoi (m68hc11_soft_reg_count);

  if (cnt < 0)
    cnt = 0;
  if (cnt > SOFT_REG_LAST - SOFT_REG_FIRST)
    cnt = SOFT_REG_LAST - SOFT_REG_FIRST;

  nb_soft_regs = cnt;
  for (i = SOFT_REG_FIRST + cnt; i < SOFT_REG_LAST; i++)
    {
      fixed_regs[i] = 1;
      call_used_regs[i] = 1;
    }

  /* For 68HC12, the Z register emulation is not necessary when the
     frame pointer is not used.  The frame pointer is eliminated and
     replaced by the stack register (which is a BASE_REG_CLASS).  */
  if (TARGET_M6812 && flag_omit_frame_pointer && optimize)
    {
      fixed_regs[HARD_Z_REGNUM] = 1;
    }
}


/* Reload and register operations.  */

static const char *const reg_class_names[] = REG_CLASS_NAMES;


void
create_regs_rtx ()
{
  /*  regs_inited = 1; */
  ix_reg = gen_rtx (REG, HImode, HARD_X_REGNUM);
  iy_reg = gen_rtx (REG, HImode, HARD_Y_REGNUM);
  d_reg = gen_rtx (REG, HImode, HARD_D_REGNUM);
  m68hc11_soft_tmp_reg = gen_rtx (REG, HImode, SOFT_TMP_REGNUM);

  stack_push_word = gen_rtx (MEM, HImode,
			     gen_rtx (PRE_DEC, HImode,
				      gen_rtx (REG, HImode, HARD_SP_REGNUM)));
  stack_pop_word = gen_rtx (MEM, HImode,
			    gen_rtx (POST_INC, HImode,
				     gen_rtx (REG, HImode, HARD_SP_REGNUM)));

}

/* Value is 1 if hard register REGNO can hold a value of machine-mode MODE.
    - 8 bit values are stored anywhere (except the SP register).
    - 16 bit values can be stored in any register whose mode is 16
    - 32 bit values can be stored in D, X registers or in a soft register
      (except the last one because we need 2 soft registers)
    - Values whose size is > 32 bit are not stored in real hard
      registers.  They may be stored in soft registers if there are
      enough of them.  */
int
hard_regno_mode_ok (regno, mode)
     int regno;
     enum machine_mode mode;
{
  switch (GET_MODE_SIZE (mode))
    {
    case 8:
      return S_REGNO_P (regno) && nb_soft_regs >= 4;

    case 4:
      return X_REGNO_P (regno) || (S_REGNO_P (regno) && nb_soft_regs >= 2);

    case 2:
      return G_REGNO_P (regno);

    case 1:
      /* We have to accept a QImode in X or Y registers.  Otherwise, the
         reload pass will fail when some (SUBREG:QI (REG:HI X)) are defined
         in the insns.  Reload fails if the insn rejects the register class 'a'
         as well as if it accepts it.  Patterns that failed were
         zero_extend_qihi2 and iorqi3.  */

      return G_REGNO_P (regno) && !SP_REGNO_P (regno);

    default:
      return 0;
    }
}

int
m68hc11_hard_regno_rename_ok (reg1, reg2)
     int reg1, reg2;
{
  /* Don't accept renaming to Z register.  We will replace it to
     X,Y or D during machine reorg pass.  */
  if (reg2 == HARD_Z_REGNUM)
    return 0;

  /* Don't accept renaming D,X to Y register as the code will be bigger.  */
  if (TARGET_M6811 && reg2 == HARD_Y_REGNUM
      && (D_REGNO_P (reg1) || X_REGNO_P (reg1)))
    return 0;

  return 1;
}

enum reg_class
preferred_reload_class (operand, class)
     rtx operand;
     enum reg_class class;
{
  enum machine_mode mode;

  mode = GET_MODE (operand);

  if (debug_m6811)
    {
      printf ("Preferred reload: (class=%s): ", reg_class_names[class]);
    }

  if (class == D_OR_A_OR_S_REGS && SP_REG_P (operand))
    return m68hc11_base_reg_class;

  if (class >= S_REGS && (GET_CODE (operand) == MEM
			  || GET_CODE (operand) == CONST_INT))
    {
      /* S_REGS class must not be used.  The movhi template does not
         work to move a memory to a soft register.
         Restrict to a hard reg.  */
      switch (class)
	{
	default:
	case G_REGS:
	case D_OR_A_OR_S_REGS:
	  class = A_OR_D_REGS;
	  break;
	case A_OR_S_REGS:
	  class = A_REGS;
	  break;
	case D_OR_SP_OR_S_REGS:
	  class = D_OR_SP_REGS;
	  break;
	case D_OR_Y_OR_S_REGS:
	  class = D_OR_Y_REGS;
	  break;
	case D_OR_X_OR_S_REGS:
	  class = D_OR_X_REGS;
	  break;
	case SP_OR_S_REGS:
	  class = SP_REGS;
	  break;
	case Y_OR_S_REGS:
	  class = Y_REGS;
	  break;
	case X_OR_S_REGS:
	  class = X_REGS;
	  break;
	case D_OR_S_REGS:
	  class = D_REGS;
	}
    }
  else if (class == Y_REGS && GET_CODE (operand) == MEM)
    {
      class = Y_REGS;
    }
  else if (class == A_OR_D_REGS && GET_MODE_SIZE (mode) == 4)
    {
      class = D_OR_X_REGS;
    }
  else if (class >= S_REGS && S_REG_P (operand))
    {
      switch (class)
	{
	default:
	case G_REGS:
	case D_OR_A_OR_S_REGS:
	  class = A_OR_D_REGS;
	  break;
	case A_OR_S_REGS:
	  class = A_REGS;
	  break;
	case D_OR_SP_OR_S_REGS:
	  class = D_OR_SP_REGS;
	  break;
	case D_OR_Y_OR_S_REGS:
	  class = D_OR_Y_REGS;
	  break;
	case D_OR_X_OR_S_REGS:
	  class = D_OR_X_REGS;
	  break;
	case SP_OR_S_REGS:
	  class = SP_REGS;
	  break;
	case Y_OR_S_REGS:
	  class = Y_REGS;
	  break;
	case X_OR_S_REGS:
	  class = X_REGS;
	  break;
	case D_OR_S_REGS:
	  class = D_REGS;
	}
    }
  else if (class >= S_REGS)
    {
      if (debug_m6811)