dwarf2dbg.c

来自「基于4个mips核的noc设计」· C语言 代码 · 共 1,313 行 · 第 1/3 页

out_byte (byte)
     int byte;
{
  FRAG_APPEND_1_CHAR (byte);
}

/* Emit a statement program opcode into the current segment.  */

static inline void
out_opcode (opc)
     int opc;
{
  out_byte (opc);
}

/* Emit a two-byte word into the current segment.  */

static inline void
out_two (data)
     int data;
{
  md_number_to_chars (frag_more (2), data, 2);
}

/* Emit a four byte word into the current segment.  */

static inline void
out_four (data)
     int data;
{
  md_number_to_chars (frag_more (4), data, 4);
}

/* Emit an unsigned "little-endian base 128" number.  */

static void
out_uleb128 (value)
     addressT value;
{
  output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
}

/* Emit a tuple for .debug_abbrev.  */

static inline void
out_abbrev (name, form)
     int name, form;
{
  out_uleb128 (name);
  out_uleb128 (form);
}

/* Create a new fake symbol whose value is the current position.  */

static symbolS *
symbol_new_now ()
{
  return symbol_new (fake_label_name, now_seg, frag_now_fix (), frag_now);
}

/* Set the value of SYM to the current position in the current segment.  */

static void
set_symbol_value_now (sym)
     symbolS *sym;
{
  S_SET_SEGMENT (sym, now_seg);
  S_SET_VALUE (sym, frag_now_fix ());
  symbol_set_frag (sym, frag_now);
}

/* Get the size of a fragment.  */

static offsetT
get_frag_fix (frag)
     fragS *frag;
{
  frchainS *fr;

  if (frag->fr_next)
    return frag->fr_fix;

  /* If a fragment is the last in the chain, special measures must be
     taken to find its size before relaxation, since it may be pending
     on some subsegment chain.  */
  for (fr = frchain_root; fr; fr = fr->frch_next)
    if (fr->frch_last == frag)
      {
	return ((char *) obstack_next_free (&fr->frch_obstack)
		- frag->fr_literal);
      }

  abort ();
}

/* Set an absolute address (may result in a relocation entry).  */

static void
out_set_addr (seg, frag, ofs)
     segT seg;
     fragS *frag;
     addressT ofs;
{
  expressionS expr;
  symbolS *sym;

  sym = symbol_new (fake_label_name, seg, ofs, frag);

  out_opcode (DW_LNS_extended_op);
  out_uleb128 (sizeof_address + 1);

  out_opcode (DW_LNE_set_address);
  expr.X_op = O_symbol;
  expr.X_add_symbol = sym;
  expr.X_add_number = 0;
  emit_expr (&expr, sizeof_address);
}

/* Encode a pair of line and address skips as efficiently as possible.
   Note that the line skip is signed, whereas the address skip is unsigned.

   The following two routines *must* be kept in sync.  This is
   enforced by making emit_inc_line_addr abort if we do not emit
   exactly the expected number of bytes.  */

static int
size_inc_line_addr (line_delta, addr_delta)
     int line_delta;
     addressT addr_delta;
{
  unsigned int tmp, opcode;
  int len = 0;

  /* Scale the address delta by the minimum instruction length.  */
#if DWARF2_LINE_MIN_INSN_LENGTH > 1
  assert (addr_delta % DWARF2_LINE_MIN_INSN_LENGTH == 0);
  addr_delta /= DWARF2_LINE_MIN_INSN_LENGTH;
#endif

  /* INT_MAX is a signal that this is actually a DW_LNE_end_sequence.
     We cannot use special opcodes here, since we want the end_sequence
     to emit the matrix entry.  */
  if (line_delta == INT_MAX)
    {
      if (addr_delta == MAX_SPECIAL_ADDR_DELTA)
	len = 1;
      else
	len = 1 + sizeof_leb128 (addr_delta, 0);
      return len + 3;
    }

  /* Bias the line delta by the base.  */
  tmp = line_delta - DWARF2_LINE_BASE;

  /* If the line increment is out of range of a special opcode, we
     must encode it with DW_LNS_advance_line.  */
  if (tmp >= DWARF2_LINE_RANGE)
    {
      len = 1 + sizeof_leb128 (line_delta, 1);
      line_delta = 0;
      tmp = 0 - DWARF2_LINE_BASE;
    }

  /* Bias the opcode by the special opcode base.  */
  tmp += DWARF2_LINE_OPCODE_BASE;

  /* Avoid overflow when addr_delta is large.  */
  if (addr_delta < 256 + MAX_SPECIAL_ADDR_DELTA)
    {
      /* Try using a special opcode.  */
      opcode = tmp + addr_delta * DWARF2_LINE_RANGE;
      if (opcode <= 255)
	return len + 1;

      /* Try using DW_LNS_const_add_pc followed by special op.  */
      opcode = tmp + (addr_delta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
      if (opcode <= 255)
	return len + 2;
    }

  /* Otherwise use DW_LNS_advance_pc.  */
  len += 1 + sizeof_leb128 (addr_delta, 0);

  /* DW_LNS_copy or special opcode.  */
  len += 1;

  return len;
}

static void
emit_inc_line_addr (line_delta, addr_delta, p, len)
     int line_delta;
     addressT addr_delta;
     char *p;
     int len;
{
  unsigned int tmp, opcode;
  int need_copy = 0;
  char *end = p + len;

#if DWARF2_LINE_MIN_INSN_LENGTH > 1
  /* Scale the address delta by the minimum instruction length.  */
  assert (addr_delta % DWARF2_LINE_MIN_INSN_LENGTH == 0);
  addr_delta /= DWARF2_LINE_MIN_INSN_LENGTH;
#endif
  /* INT_MAX is a signal that this is actually a DW_LNE_end_sequence.
     We cannot use special opcodes here, since we want the end_sequence
     to emit the matrix entry.  */
  if (line_delta == INT_MAX)
    {
      if (addr_delta == MAX_SPECIAL_ADDR_DELTA)
	*p++ = DW_LNS_const_add_pc;
      else
	{
	  *p++ = DW_LNS_advance_pc;
	  p += output_leb128 (p, addr_delta, 0);
	}

      *p++ = DW_LNS_extended_op;
      *p++ = 1;
      *p++ = DW_LNE_end_sequence;
      goto done;
    }

  /* Bias the line delta by the base.  */
  tmp = line_delta - DWARF2_LINE_BASE;

  /* If the line increment is out of range of a special opcode, we
     must encode it with DW_LNS_advance_line.  */
  if (tmp >= DWARF2_LINE_RANGE)
    {
      *p++ = DW_LNS_advance_line;
      p += output_leb128 (p, line_delta, 1);

      /* Prettier, I think, to use DW_LNS_copy instead of a
	 "line +0, addr +0" special opcode.  */
      if (addr_delta == 0)
	{
	  *p++ = DW_LNS_copy;
	  goto done;
	}

      line_delta = 0;
      tmp = 0 - DWARF2_LINE_BASE;
      need_copy = 1;
    }

  /* Bias the opcode by the special opcode base.  */
  tmp += DWARF2_LINE_OPCODE_BASE;

  /* Avoid overflow when addr_delta is large.  */
  if (addr_delta < 256 + MAX_SPECIAL_ADDR_DELTA)
    {
      /* Try using a special opcode.  */
      opcode = tmp + addr_delta * DWARF2_LINE_RANGE;
      if (opcode <= 255)
	{
	  *p++ = opcode;
	  goto done;
	}

      /* Try using DW_LNS_const_add_pc followed by special op.  */
      opcode = tmp + (addr_delta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
      if (opcode <= 255)
	{
	  *p++ = DW_LNS_const_add_pc;
	  *p++ = opcode;
	  goto done;
	}
    }

  /* Otherwise use DW_LNS_advance_pc.  */
  *p++ = DW_LNS_advance_pc;
  p += output_leb128 (p, addr_delta, 0);

  if (need_copy)
    *p++ = DW_LNS_copy;
  else
    *p++ = tmp;

 done:
  assert (p == end);
}

/* Handy routine to combine calls to the above two routines.  */

static void
out_inc_line_addr (line_delta, addr_delta)
     int line_delta;
     addressT addr_delta;
{
  int len = size_inc_line_addr (line_delta, addr_delta);
  emit_inc_line_addr (line_delta, addr_delta, frag_more (len), len);
}

/* Generate a variant frag that we can use to relax address/line
   increments between fragments of the target segment.  */

static void
relax_inc_line_addr (line_delta, seg, to_frag, to_ofs, from_frag, from_ofs)
     int line_delta;
     segT seg;
     fragS *to_frag, *from_frag;
     addressT to_ofs, from_ofs;
{
  symbolS *to_sym, *from_sym;
  expressionS expr;
  int max_chars;

  to_sym = symbol_new (fake_label_name, seg, to_ofs, to_frag);
  from_sym = symbol_new (fake_label_name, seg, from_ofs, from_frag);

  expr.X_op = O_subtract;
  expr.X_add_symbol = to_sym;
  expr.X_op_symbol = from_sym;
  expr.X_add_number = 0;

  /* The maximum size of the frag is the line delta with a maximum
     sized address delta.  */
  max_chars = size_inc_line_addr (line_delta, -DWARF2_LINE_MIN_INSN_LENGTH);

  frag_var (rs_dwarf2dbg, max_chars, max_chars, 1,
	    make_expr_symbol (&expr), line_delta, NULL);
}

/* The function estimates the size of a rs_dwarf2dbg variant frag
   based on the current values of the symbols.  It is called before
   the relaxation loop.  We set fr_subtype to the expected length.  */

int
dwarf2dbg_estimate_size_before_relax (frag)
     fragS *frag;
{
  offsetT addr_delta;
  int size;

  addr_delta = resolve_symbol_value (frag->fr_symbol, 0);
  size = size_inc_line_addr (frag->fr_offset, addr_delta);

  frag->fr_subtype = size;

  return size;
}

/* This function relaxes a rs_dwarf2dbg variant frag based on the
   current values of the symbols.  fr_subtype is the current length
   of the frag.  This returns the change in frag length.  */

int
dwarf2dbg_relax_frag (frag)
     fragS *frag;
{
  int old_size, new_size;

  old_size = frag->fr_subtype;
  new_size = dwarf2dbg_estimate_size_before_relax (frag);

  return new_size - old_size;
}

/* This function converts a rs_dwarf2dbg variant frag into a normal
   fill frag.  This is called after all relaxation has been done.
   fr_subtype will be the desired length of the frag.  */

void
dwarf2dbg_convert_frag (frag)
     fragS *frag;
{
  offsetT addr_diff;

  addr_diff = resolve_symbol_value (frag->fr_symbol, 1);

  /* fr_var carries the max_chars that we created the fragment with.
     fr_subtype carries the current expected length.  We must, of
     course, have allocated enough memory earlier.  */
  assert (frag->fr_var >= (int) frag->fr_subtype);

  emit_inc_line_addr (frag->fr_offset, addr_diff,
		      frag->fr_literal + frag->fr_fix, frag->fr_subtype);

  frag->fr_fix += frag->fr_subtype;
  frag->fr_type = rs_fill;
  frag->fr_var = 0;
  frag->fr_offset = 0;
}

/* Generate .debug_line content for the chain of line number entries
   beginning at E, for segment SEG.  */

static void
process_entries (seg, e)
     segT seg;
     struct line_entry *e;
{
  unsigned filenum = 1;
  unsigned line = 1;
  unsigned column = 0;
  unsigned flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_BEGIN_STMT : 0;
  fragS *frag = NULL;
  fragS *last_frag;
  addressT frag_ofs = 0;
  addressT last_frag_ofs;
  struct line_entry *next;

  while (e)
    {
      int changed = 0;

      if (filenum != e->loc.filenum)
	{
	  filenum = e->loc.filenum;
	  out_opcode (DW_LNS_set_file);
	  out_uleb128 (filenum);
	  changed = 1;
	}

      if (column != e->loc.column)
	{
	  column = e->loc.column;
	  out_opcode (DW_LNS_set_column);
	  out_uleb128 (column);
	  changed = 1;
	}

      if ((e->loc.flags ^ flags) & DWARF2_FLAG_BEGIN_STMT)
	{
	  flags = e->loc.flags;
	  out_opcode (DW_LNS_negate_stmt);
	  changed = 1;
	}

      if (e->loc.flags & DWARF2_FLAG_BEGIN_BLOCK)
	{
	  out_opcode (DW_LNS_set_basic_block);
	  changed = 1;
	}

      /* Don't try to optimize away redundant entries; gdb wants two