gas/config/tc-ft32.c

/* tc-ft32.c -- Assemble code for ft32
   Copyright (C) 2008-2021 Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS 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 3, or (at your option)
   any later version.

   GAS 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 GAS; see the file COPYING.  If not, write to
   the Free Software Foundation, 51 Franklin Street - Fifth Floor,
   Boston, MA 02110-1301, USA.  */

/* Contributed by Anthony Green <green@spindazzle.org>.  */

#include "as.h"
#include "safe-ctype.h"
#include "opcode/ft32.h"

extern const ft32_opc_info_t ft32_opc_info[128];

/* See md_parse_option() for meanings of these options.  */
static char norelax;			/* True if -norelax switch seen.  */

const char comment_chars[]        = "#";
const char line_separator_chars[] = ";";
const char line_comment_chars[]   = "#";

static int pending_reloc;
static htab_t opcode_hash_control;

static valueT md_chars_to_number (char * buf, int n);

const pseudo_typeS md_pseudo_table[] =
{
  {0, 0, 0}
};

const char FLT_CHARS[] = "rRsSfFdDxXpP";
const char EXP_CHARS[] = "eE";

/* This function is called once, at assembler startup time.  It sets
   up the hash table with all the opcodes in it, and also initializes
   some aliases for compatibility with other assemblers.  */

void
md_begin (void)
{
  const ft32_opc_info_t *opcode;
  opcode_hash_control = str_htab_create ();

  /* Insert names into hash table.  */
  for (opcode = ft32_opc_info; opcode->name; opcode++)
    str_hash_insert (opcode_hash_control, opcode->name, opcode, 0);

  bfd_set_arch_mach (stdoutput, TARGET_ARCH, 0);
  if (!norelax)
    linkrelax = 1;
}

/* Parse an expression and then restore the input line pointer.  */

static char *
parse_exp_save_ilp (char *s, expressionS *op)
{
  char *save = input_line_pointer;

  input_line_pointer = s;
  expression (op);
  s = input_line_pointer;
  input_line_pointer = save;
  return s;
}

static int
parse_condition (char **ptr)
{
  char *s = *ptr;
  static const struct
  {
    const char *name;
    int bits;
  }
  ccs[] =
  {
    { "gt,"   , (2 << FT32_FLD_CR_BIT) | (5 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "gte,"  , (2 << FT32_FLD_CR_BIT) | (4 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "lt,"   , (2 << FT32_FLD_CR_BIT) | (4 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "lte,"  , (2 << FT32_FLD_CR_BIT) | (5 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "a,"    , (2 << FT32_FLD_CR_BIT) | (6 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "ae,"   , (2 << FT32_FLD_CR_BIT) | (1 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "be,"   , (2 << FT32_FLD_CR_BIT) | (6 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "b,"    , (2 << FT32_FLD_CR_BIT) | (1 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "nz,"   , (2 << FT32_FLD_CR_BIT) | (0 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "z,"    , (2 << FT32_FLD_CR_BIT) | (0 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "nc,"   , (2 << FT32_FLD_CR_BIT) | (1 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "c,"    , (2 << FT32_FLD_CR_BIT) | (1 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "no,"   , (2 << FT32_FLD_CR_BIT) | (2 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "o,"    , (2 << FT32_FLD_CR_BIT) | (2 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { "ns,"   , (2 << FT32_FLD_CR_BIT) | (3 << FT32_FLD_CB_BIT) | (0 << FT32_FLD_CV_BIT)},
    { "s,"    , (2 << FT32_FLD_CR_BIT) | (3 << FT32_FLD_CB_BIT) | (1 << FT32_FLD_CV_BIT)},
    { NULL, 0}
  }, *pc;

  for (pc = ccs; pc->name; pc++)
    {
      if (memcmp(pc->name, s, strlen(pc->name)) == 0)
        {
          *ptr += strlen(pc->name) - 1;
          return pc->bits;
        }
    }
  return -1;
}

static int
parse_decimal (char **ptr)
{
  int r = 0;
  char *s = *ptr;

  while (('0' <= *s) && (*s <= '9'))
    {
      r *= 10;
      r += (*s++ - '0');
    }
  *ptr = s;
  return r;
}

static int
parse_register_operand (char **ptr)
{
  int reg;
  char *s = *ptr;

  if (*s != '$')
    {
      as_bad (_("expecting register"));
      ignore_rest_of_line ();
      return -1;
    }
  if ((s[1] == 's') && (s[2] == 'p'))
    {
      reg = 31;
    }
  else if ((s[1] == 'c') && (s[2] == 'c'))
    {
      reg = 30;
    }
  else if ((s[1] == 'f') && (s[2] == 'p'))
    {
      reg = 29;
    }
  else if (s[1] == 'r')
    {
      reg = s[2] - '0';
      if ((reg < 0) || (reg > 9))
	{
	  as_bad (_("illegal register number"));
	  ignore_rest_of_line ();
	  return -1;
	}
      if ((reg == 1) || (reg == 2) || (reg == 3))
	{
	  int r2 = s[3] - '0';
	  if ((r2 >= 0) && (r2 <= 9))
	    {
	      reg = (reg * 10) + r2;
	      *ptr += 1;
	    }
	}
    }
  else
    {
      as_bad (_("illegal register number"));
      ignore_rest_of_line ();
      return -1;
    }

  *ptr += 3;

  return reg;
}

/* This is the guts of the machine-dependent assembler.  STR points to
   a machine dependent instruction.  This function is supposed to emit
   the frags/bytes it assembles to.  */

void
md_assemble (char *str)
{
  char *op_start;
  char *op_end;
  ft32_opc_info_t *opcode;
  char *output;
  int idx = 0;
  char pend;
  int nlen = 0;
  unsigned int b;
  int f;
  expressionS arg;
  bool fixed = false;
  unsigned int sc;
  bool can_sc;

  /* Drop leading whitespace.  */
  while (*str == ' ')
    str++;

  /* Find the op code end.  */
  op_start = str;
  for (op_end = str;
       *op_end
       && !is_end_of_line[*op_end & 0xff]
       && *op_end != ' '
       && *op_end != '.';
       op_end++)
    nlen++;

  pend = *op_end;
  *op_end = 0;

  if (nlen == 0)
    as_bad (_("can't find opcode "));

  opcode = (ft32_opc_info_t *) str_hash_find (opcode_hash_control, op_start);
  *op_end = pend;

  if (opcode == NULL)
    {
      as_bad (_("unknown opcode %s"), op_start);
      return;
    }

  b = opcode->bits;
  f = opcode->fields;

  if (opcode->dw)
    {
      int dw;

      if (*op_end == '.')
        {
          switch (op_end[1])
            {
              case 'b':
                dw = 0;
                break;
              case 's':
                dw = 1;
                break;
              case 'l':
                dw = 2;
                break;
              default:
                as_bad (_("unknown width specifier '.%c'"), op_end[1]);
                return;
            }
          op_end += 2;
        }
      else
        {
          dw = 2; /* default is ".l" */
        }
      b |= dw << FT32_FLD_DW_BIT;
    }

  while (ISSPACE (*op_end))
    op_end++;

  output = frag_more (4);

  while (f)
    {
      int lobit = f & -f;

      if (f & lobit)
        {
          switch (lobit)
	    {
	    case  FT32_FLD_CBCRCV:
	      b |= parse_condition( &op_end);
	      break;
	    case  FT32_FLD_CB:
	      b |= parse_decimal (&op_end) << FT32_FLD_CB_BIT;
	      break;
	    case  FT32_FLD_R_D:
	      b |= parse_register_operand (&op_end) << FT32_FLD_R_D_BIT;
	      break;
	    case  FT32_FLD_CR:
	      b |= (parse_register_operand (&op_end) - 28) << FT32_FLD_CR_BIT;
	      break;
	    case  FT32_FLD_CV:
	      b |= parse_decimal (&op_end) << FT32_FLD_CV_BIT;
	      break;
	    case  FT32_FLD_R_1:
	      b |= parse_register_operand (&op_end) << FT32_FLD_R_1_BIT;
	      break;
	    case  FT32_FLD_RIMM:
	      if (*op_end == '$')
		{
		  b |= parse_register_operand (&op_end) << FT32_FLD_RIMM_BIT;
		}
	      else
		{
		  b |= 0x400 << FT32_FLD_RIMM_BIT;
		  op_end = parse_exp_save_ilp (op_end, &arg);
		  fixed = true;
		  fix_new_exp (frag_now,
			       (output - frag_now->fr_literal),
			       2,
			       &arg,
			       0,
			       BFD_RELOC_FT32_10);
		}
	      break;
	    case  FT32_FLD_R_2:
	      b |= parse_register_operand (&op_end) << FT32_FLD_R_2_BIT;
	      break;
	    case  FT32_FLD_K20:
	      op_end = parse_exp_save_ilp (op_end, &arg);
	      fixed = true;
	      fix_new_exp (frag_now,
			   (output - frag_now->fr_literal),
			   3,
			   &arg,
			   0,
			   BFD_RELOC_FT32_20);
	      break;
	    case  FT32_FLD_PA:
	      op_end = parse_exp_save_ilp (op_end, &arg);
	      fixed = true;
	      fix_new_exp (frag_now,
			   (output - frag_now->fr_literal),
			   3,
			   &arg,
			   0,
			   BFD_RELOC_FT32_18);
	      break;
	    case  FT32_FLD_AA:
	      op_end = parse_exp_save_ilp (op_end, &arg);
	      fixed = true;
	      fix_new_exp (frag_now,
			   (output - frag_now->fr_literal),
			   3,
			   &arg,
			   0,
			   BFD_RELOC_FT32_17);
	      break;
	    case  FT32_FLD_K16:
	      op_end = parse_exp_save_ilp (op_end, &arg);
	      fixed = true;
	      fix_new_exp (frag_now,
			   (output - frag_now->fr_literal),
			   2,
			   &arg,
			   0,
			   BFD_RELOC_16);
	      break;
	    case  FT32_FLD_K15:
	      op_end = parse_exp_save_ilp (op_end, &arg);
	      if (arg.X_add_number & 0x80)
		arg.X_add_number ^= 0x7f00;
	      fixed = true;
	      fix_new_exp (frag_now,
			   (output - frag_now->fr_literal),
			   2,
			   &arg,
			   0,
			   BFD_RELOC_FT32_15);
	      break;
	    case  FT32_FLD_R_D_POST:
	      b |= parse_register_operand (&op_end) << FT32_FLD_R_D_BIT;
	      break;
	    case  FT32_FLD_R_1_POST:
	      b |= parse_register_operand (&op_end) << FT32_FLD_R_1_BIT;
	      break;
	    default:
	      as_bad (_("internal error in argument parsing"));
	      break;
	    }

          f &= ~lobit;

          if (f)
            {
              while (ISSPACE (*op_end))
                op_end++;

              if (*op_end != ',')
                {
                  as_bad (_("expected comma separator"));
                  ignore_rest_of_line ();
                }

              op_end++;
              while (ISSPACE (*op_end))
                op_end++;
            }
        }
    }

  if (*op_end != 0)
    as_warn (_("extra stuff on line ignored"));

  can_sc = ft32_shortcode (b, &sc);

  if (!fixed && can_sc)
    {
      arg.X_op = O_constant;
      arg.X_add_number = 0;
      arg.X_add_symbol = NULL;
      arg.X_op_symbol = NULL;
      fix_new_exp (frag_now,
                   (output - frag_now->fr_literal),
                   2,
                   &arg,
                   0,
                   BFD_RELOC_FT32_RELAX);
    }

  output[idx++] = 0xff & (b >> 0);
  output[idx++] = 0xff & (b >> 8);
  output[idx++] = 0xff & (b >> 16);
  output[idx++] = 0xff & (b >> 24);

  dwarf2_emit_insn (4);

  while (ISSPACE (*op_end))
    op_end++;

  if (*op_end != 0)
    as_warn ("extra stuff on line ignored");

  if (pending_reloc)
    as_bad ("Something forgot to clean up\n");
}

/* Turn a string in input_line_pointer into a floating point constant
   of type type, and store the appropriate bytes in *LITP.  The number
   of LITTLENUMS emitted is stored in *SIZEP .  An error message is
   returned, or NULL on OK.  */

const char *
md_atof (int type, char *litP, int *sizeP)
{
  int prec;
  LITTLENUM_TYPE words[4];
  char *t;
  int i;

  switch (type)
    {
    case 'f':
      prec = 2;
      break;

    case 'd':
      prec = 4;
      break;

    default:
      *sizeP = 0;
      return _("bad call to md_atof");
    }

  t = atof_ieee (input_line_pointer, type, words);
  if (t)
    input_line_pointer = t;

  *sizeP = prec * 2;

  for (i = prec - 1; i >= 0; i--)
    {
      md_number_to_chars (litP, (valueT) words[i], 2);
      litP += 2;
    }

  return NULL;
}

const char *md_shortopts = "";

struct option md_longopts[] =
{
#define OPTION_NORELAX (OPTION_MD_BASE)
  {"norelax", no_argument, NULL, OPTION_NORELAX},
  {"no-relax", no_argument, NULL, OPTION_NORELAX},
  {NULL, no_argument, NULL, 0}
};
size_t md_longopts_size = sizeof (md_longopts);

/* We have no target specific options yet, so these next
   two functions are empty.  */
int
md_parse_option (int c ATTRIBUTE_UNUSED, const char *arg ATTRIBUTE_UNUSED)
{
  switch (c)
    {
    case OPTION_NORELAX:
      norelax = 1;
      break;

    default:
      return 0;
    }

  return 1;
}

void
md_show_usage (FILE *stream ATTRIBUTE_UNUSED)
{
  fprintf (stream, _("FT32 options:\n"));
  fprintf (stream, _("\n\
-no-relax		don't relax relocations\n\
			\n"));
}

/* Convert from target byte order to host byte order.  */

static valueT
md_chars_to_number (char * buf, int n)
{
  valueT result = 0;
  unsigned char * where = (unsigned char *) buf;

  while (n--)
    {
      result <<= 8;
      result |= (where[n] & 255);
    }

  return result;
}

/* Apply a fixup to the object file.  */

void
md_apply_fix (fixS *fixP ATTRIBUTE_UNUSED,
	      valueT * valP ATTRIBUTE_UNUSED, segT seg ATTRIBUTE_UNUSED)
{
  char *buf = fixP->fx_where + fixP->fx_frag->fr_literal;
  long val = *valP;
  long newval;

  if (linkrelax && fixP->fx_subsy)
    {
      /* For a subtraction relocation expression, generate one
         of the DIFF relocs, with the value being the difference.
         Note that a sym1 - sym2 expression is adjusted into a
         section_start_sym + sym4_offset_from_section_start - sym1
         expression. fixP->fx_addsy holds the section start symbol,
         fixP->fx_offset holds sym2's offset, and fixP->fx_subsy
         holds sym1. Calculate the current difference and write value,
         but leave fx_offset as is - during relaxation,
         fx_offset - value gives sym1's value.  */

       switch (fixP->fx_r_type)
         {
           case BFD_RELOC_32:
             fixP->fx_r_type = BFD_RELOC_FT32_DIFF32;
             break;
           default:
             as_bad_subtract (fixP);
             break;
         }

      val = S_GET_VALUE (fixP->fx_addsy) +
          fixP->fx_offset - S_GET_VALUE (fixP->fx_subsy);
      *valP = val;

      fixP->fx_subsy = NULL;
  }

  /* We don't actually support subtracting a symbol.  */
  if (fixP->fx_subsy != (symbolS *) NULL)
    as_bad_subtract (fixP);

  switch (fixP->fx_r_type)
    {
    case BFD_RELOC_FT32_DIFF32:
    case BFD_RELOC_32:
      buf[3] = val >> 24;
      buf[2] = val >> 16;
      buf[1] = val >> 8;
      buf[0] = val >> 0;
      break;

    case BFD_RELOC_16:
      buf[1] = val >> 8;
      buf[0] = val >> 0;
      break;

    case BFD_RELOC_8:
      *buf = val;
      break;

    case BFD_RELOC_FT32_10:
      if (!val)
	break;
      newval = md_chars_to_number (buf, 2);
      newval |= (val & ((1 << 10) - 1)) << FT32_FLD_RIMM_BIT;
      md_number_to_chars (buf, newval, 2);
      break;

    case BFD_RELOC_FT32_20:
      if (!val)
	break;
      newval = md_chars_to_number (buf, 3);
      newval |= val & ((1 << 20) - 1);
      md_number_to_chars (buf, newval, 3);
      break;

    case BFD_RELOC_FT32_15:
      if (!val)
	break;
      newval = md_chars_to_number (buf, 2);
      newval |= val & ((1 << 15) - 1);
      md_number_to_chars (buf, newval, 2);
      break;

    case BFD_RELOC_FT32_17:
      if (!val)
	break;
      newval = md_chars_to_number (buf, 3);
      newval |= val & ((1 << 17) - 1);
      md_number_to_chars (buf, newval, 3);
      break;

    case BFD_RELOC_FT32_18:
      if (!val)
	break;
      newval = md_chars_to_number (buf, 4);
      newval |= (val >> 2) & ((1 << 18) - 1);
      md_number_to_chars (buf, newval, 4);
      break;

    case BFD_RELOC_FT32_RELAX:
      break;

    default:
      abort ();
    }

  if (fixP->fx_addsy == NULL && fixP->fx_pcrel == 0)
    fixP->fx_done = 1;
}

void
md_number_to_chars (char *ptr, valueT use, int nbytes)
{
  number_to_chars_littleendian (ptr, use, nbytes);
}

/* Generate a machine-dependent relocation.  */

arelent *
tc_gen_reloc (asection *section ATTRIBUTE_UNUSED, fixS *fixP)
{
  arelent *relP;
  bfd_reloc_code_real_type code;

  switch (fixP->fx_r_type)
    {
    case BFD_RELOC_32:
    case BFD_RELOC_16:
    case BFD_RELOC_8:
    case BFD_RELOC_FT32_10:
    case BFD_RELOC_FT32_20:
    case BFD_RELOC_FT32_15:
    case BFD_RELOC_FT32_17:
    case BFD_RELOC_FT32_18:
    case BFD_RELOC_FT32_RELAX:
    case BFD_RELOC_FT32_DIFF32:
      code = fixP->fx_r_type;
      break;
    default:
      as_bad_where (fixP->fx_file, fixP->fx_line,
		    _("Semantics error.  This type of operand can not be "
                      "relocated, it must be an assembly-time constant"));
      return NULL;
    }

  relP = XNEW (arelent);
  gas_assert (relP != 0);
  relP->sym_ptr_ptr = XNEW (asymbol *);
  *relP->sym_ptr_ptr = symbol_get_bfdsym (fixP->fx_addsy);
  relP->address = fixP->fx_frag->fr_address + fixP->fx_where;

  relP->addend = fixP->fx_offset;

  relP->howto = bfd_reloc_type_lookup (stdoutput, code);
  if (! relP->howto)
    {
      const char *name;

      name = S_GET_NAME (fixP->fx_addsy);
      if (name == NULL)
	name = _("<unknown>");
      as_fatal (_("Cannot generate relocation type for symbol %s, code %s"),
		name, bfd_get_reloc_code_name (code));
    }

  return relP;
}

/* TC_FORCE_RELOCATION hook */

static bool
relaxable_section (asection *sec)
{
  return ((sec->flags & SEC_DEBUGGING) == 0
          && (sec->flags & SEC_CODE) != 0
          && (sec->flags & SEC_ALLOC) != 0);
}

/* Does whatever the xtensa port does.  */

int
ft32_validate_fix_sub (fixS *fix)
{
  segT add_symbol_segment, sub_symbol_segment;

  /* The difference of two symbols should be resolved by the assembler when
     linkrelax is not set.  If the linker may relax the section containing
     the symbols, then an Xtensa DIFF relocation must be generated so that
     the linker knows to adjust the difference value.  */
  if (!linkrelax || fix->fx_addsy == NULL)
    return 0;

  /* Make sure both symbols are in the same segment, and that segment is
     "normal" and relaxable.  If the segment is not "normal", then the
     fix is not valid.  If the segment is not "relaxable", then the fix
     should have been handled earlier.  */
  add_symbol_segment = S_GET_SEGMENT (fix->fx_addsy);
  if (! SEG_NORMAL (add_symbol_segment) ||
      ! relaxable_section (add_symbol_segment))
    return 0;

  sub_symbol_segment = S_GET_SEGMENT (fix->fx_subsy);
  return (sub_symbol_segment == add_symbol_segment);
}

/* TC_FORCE_RELOCATION hook */

/* If linkrelax is turned on, and the symbol to relocate
   against is in a relaxable segment, don't compute the value -
   generate a relocation instead.  */

int
ft32_force_relocation (fixS *fix)
{
  if (linkrelax && fix->fx_addsy
      && relaxable_section (S_GET_SEGMENT (fix->fx_addsy)))
    {
      return 1;
    }

  return generic_force_reloc (fix);
}

bool
ft32_allow_local_subtract (expressionS * left,
			   expressionS * right,
			   segT section)
{
  /* If we are not in relaxation mode, subtraction is OK.  */
  if (!linkrelax)
    return true;

  /* If the symbols are not in a code section then they are OK.  */
  if ((section->flags & SEC_CODE) == 0)
    return true;

  if (left->X_add_symbol == right->X_add_symbol)
    return true;

  /* We have to assume that there may be instructions between the
     two symbols and that relaxation may increase the distance between
     them.  */
  return false;
}