cond.c

/* cond.c - conditional assembly pseudo-ops, and .include
   Copyright (C) 1990-2017 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.  */

#include "as.h"
#include "sb.h"
#include "macro.h"

#include "obstack.h"

/* This is allocated to grow and shrink as .ifdef/.endif pairs are
   scanned.  */
struct obstack cond_obstack;

struct file_line {
  const char *file;
  unsigned int line;
};

/* We push one of these structures for each .if, and pop it at the
   .endif.  */

struct conditional_frame {
  /* The source file & line number of the "if".  */
  struct file_line if_file_line;
  /* The source file & line of the "else".  */
  struct file_line else_file_line;
  /* The previous conditional.  */
  struct conditional_frame *previous_cframe;
  /* Have we seen an else yet?  */
  int else_seen;
  /* Whether we are currently ignoring input.  */
  int ignoring;
  /* Whether a conditional at a higher level is ignoring input.
     Set also when a branch of an "if .. elseif .." tree has matched
     to prevent further matches.  */
  int dead_tree;
  /* Macro nesting level at which this conditional was created.  */
  int macro_nest;
};

static void initialize_cframe (struct conditional_frame *cframe);
static char *get_mri_string (int, int *);

static struct conditional_frame *current_cframe = NULL;

/* Performs the .ifdef (test_defined == 1) and
   the .ifndef (test_defined == 0) pseudo op.  */

void
s_ifdef (int test_defined)
{
  /* Points to name of symbol.  */
  char *name;
  /* Points to symbol.  */
  symbolS *symbolP;
  struct conditional_frame cframe;
  char c;

  /* Leading whitespace is part of operand.  */
  SKIP_WHITESPACE ();
  name = input_line_pointer;

  if (!is_name_beginner (*name) && *name != '"')
    {
      as_bad (_("invalid identifier for \".ifdef\""));
      obstack_1grow (&cond_obstack, 0);
      ignore_rest_of_line ();
      return;
    }

  c = get_symbol_name (& name);
  symbolP = symbol_find (name);
  (void) restore_line_pointer (c);

  initialize_cframe (&cframe);

  if (cframe.dead_tree)
    cframe.ignoring = 1;
  else
    {
      int is_defined;

      /* Use the same definition of 'defined' as .equiv so that a symbol
	 which has been referenced but not yet given a value/address is
	 considered to be undefined.  */
      is_defined =
	symbolP != NULL
	&& (S_IS_DEFINED (symbolP) || symbol_equated_p (symbolP))
	&& S_GET_SEGMENT (symbolP) != reg_section;

      cframe.ignoring = ! (test_defined ^ is_defined);
    }

  current_cframe = ((struct conditional_frame *)
		    obstack_copy (&cond_obstack, &cframe,
				  sizeof (cframe)));

  if (LISTING_SKIP_COND ()
      && cframe.ignoring
      && (cframe.previous_cframe == NULL
	  || ! cframe.previous_cframe->ignoring))
    listing_list (2);

  demand_empty_rest_of_line ();
}

void
s_if (int arg)
{
  expressionS operand;
  struct conditional_frame cframe;
  int t;
  char *stop = NULL;
  char stopc = 0;

  if (flag_mri)
    stop = mri_comment_field (&stopc);

  /* Leading whitespace is part of operand.  */
  SKIP_WHITESPACE ();

  if (current_cframe != NULL && current_cframe->ignoring)
    {
      operand.X_add_number = 0;
      while (! is_end_of_line[(unsigned char) *input_line_pointer])
	++input_line_pointer;
    }
  else
    {
      expression_and_evaluate (&operand);
      if (operand.X_op != O_constant)
	as_bad (_("non-constant expression in \".if\" statement"));
    }

  switch ((operatorT) arg)
    {
    case O_eq: t = operand.X_add_number == 0; break;
    case O_ne: t = operand.X_add_number != 0; break;
    case O_lt: t = operand.X_add_number < 0; break;
    case O_le: t = operand.X_add_number <= 0; break;
    case O_ge: t = operand.X_add_number >= 0; break;
    case O_gt: t = operand.X_add_number > 0; break;
    default:
      abort ();
      return;
    }

  /* If the above error is signaled, this will dispatch
     using an undefined result.  No big deal.  */
  initialize_cframe (&cframe);
  cframe.ignoring = cframe.dead_tree || ! t;
  current_cframe = ((struct conditional_frame *)
		    obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));

  if (LISTING_SKIP_COND ()
      && cframe.ignoring
      && (cframe.previous_cframe == NULL
	  || ! cframe.previous_cframe->ignoring))
    listing_list (2);

  if (flag_mri)
    mri_comment_end (stop, stopc);

  demand_empty_rest_of_line ();
}

/* Performs the .ifb (test_blank == 1) and
   the .ifnb (test_blank == 0) pseudo op.  */

void
s_ifb (int test_blank)
{
  struct conditional_frame cframe;

  initialize_cframe (&cframe);

  if (cframe.dead_tree)
    cframe.ignoring = 1;
  else
    {
      int is_eol;

      SKIP_WHITESPACE ();
      is_eol = is_end_of_line[(unsigned char) *input_line_pointer];
      cframe.ignoring = (test_blank == !is_eol);
    }

  current_cframe = ((struct conditional_frame *)
		    obstack_copy (&cond_obstack, &cframe,
				  sizeof (cframe)));

  if (LISTING_SKIP_COND ()
      && cframe.ignoring
      && (cframe.previous_cframe == NULL
	  || ! cframe.previous_cframe->ignoring))
    listing_list (2);

  ignore_rest_of_line ();
}

/* Get a string for the MRI IFC or IFNC pseudo-ops.  */

static char *
get_mri_string (int terminator, int *len)
{
  char *ret;
  char *s;

  SKIP_WHITESPACE ();
  s = ret = input_line_pointer;
  if (*input_line_pointer == '\'')
    {
      ++s;
      ++input_line_pointer;
      while (! is_end_of_line[(unsigned char) *input_line_pointer])
	{
	  *s++ = *input_line_pointer++;
	  if (s[-1] == '\'')
	    {
	      if (*input_line_pointer != '\'')
		break;
	      ++input_line_pointer;
	    }
	}
      SKIP_WHITESPACE ();
    }
  else
    {
      while (*input_line_pointer != terminator
	     && ! is_end_of_line[(unsigned char) *input_line_pointer])
	++input_line_pointer;
      s = input_line_pointer;
      while (s > ret && (s[-1] == ' ' || s[-1] == '\t'))
	--s;
    }

  *len = s - ret;
  return ret;
}

/* The MRI IFC and IFNC pseudo-ops.  */

void
s_ifc (int arg)
{
  char *stop = NULL;
  char stopc = 0;
  char *s1, *s2;
  int len1, len2;
  int res;
  struct conditional_frame cframe;

  if (flag_mri)
    stop = mri_comment_field (&stopc);

  s1 = get_mri_string (',', &len1);

  if (*input_line_pointer != ',')
    as_bad (_("bad format for ifc or ifnc"));
  else
    ++input_line_pointer;

  s2 = get_mri_string (';', &len2);

  res = len1 == len2 && strncmp (s1, s2, len1) == 0;

  initialize_cframe (&cframe);
  cframe.ignoring = cframe.dead_tree || ! (res ^ arg);
  current_cframe = ((struct conditional_frame *)
		    obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));

  if (LISTING_SKIP_COND ()
      && cframe.ignoring
      && (cframe.previous_cframe == NULL
	  || ! cframe.previous_cframe->ignoring))
    listing_list (2);

  if (flag_mri)
    mri_comment_end (stop, stopc);

  demand_empty_rest_of_line ();
}

void
s_elseif (int arg)
{
  if (current_cframe == NULL)
    {
      as_bad (_("\".elseif\" without matching \".if\""));
    }
  else if (current_cframe->else_seen)
    {
      as_bad (_("\".elseif\" after \".else\""));
      as_bad_where (current_cframe->else_file_line.file,
		    current_cframe->else_file_line.line,
		    _("here is the previous \".else\""));
      as_bad_where (current_cframe->if_file_line.file,
		    current_cframe->if_file_line.line,
		    _("here is the previous \".if\""));
    }
  else
    {
      current_cframe->else_file_line.file
       	= as_where (&current_cframe->else_file_line.line);

      current_cframe->dead_tree |= !current_cframe->ignoring;
      current_cframe->ignoring = current_cframe->dead_tree;
    }

  if (current_cframe == NULL || current_cframe->ignoring)
    {
      while (! is_end_of_line[(unsigned char) *input_line_pointer])
	++input_line_pointer;

      if (current_cframe == NULL)
	return;
    }
  else
    {
      expressionS operand;
      int t;

      /* Leading whitespace is part of operand.  */
      SKIP_WHITESPACE ();

      expression_and_evaluate (&operand);
      if (operand.X_op != O_constant)
	as_bad (_("non-constant expression in \".elseif\" statement"));

      switch ((operatorT) arg)
	{
	case O_eq: t = operand.X_add_number == 0; break;
	case O_ne: t = operand.X_add_number != 0; break;
	case O_lt: t = operand.X_add_number < 0; break;
	case O_le: t = operand.X_add_number <= 0; break;
	case O_ge: t = operand.X_add_number >= 0; break;
	case O_gt: t = operand.X_add_number > 0; break;
	default:
	  abort ();
	  return;
	}

      current_cframe->ignoring = current_cframe->dead_tree || ! t;
    }

  if (LISTING_SKIP_COND ()
      && (current_cframe->previous_cframe == NULL
	  || ! current_cframe->previous_cframe->ignoring))
    {
      if (! current_cframe->ignoring)
	listing_list (1);
      else
	listing_list (2);
    }

  demand_empty_rest_of_line ();
}

void
s_endif (int arg ATTRIBUTE_UNUSED)
{
  struct conditional_frame *hold;

  if (current_cframe == NULL)
    {
      as_bad (_("\".endif\" without \".if\""));
    }
  else
    {
      if (LISTING_SKIP_COND ()
	  && current_cframe->ignoring
	  && (current_cframe->previous_cframe == NULL
	      || ! current_cframe->previous_cframe->ignoring))
	listing_list (1);

      hold = current_cframe;
      current_cframe = current_cframe->previous_cframe;
      obstack_free (&cond_obstack, hold);
    }				/* if one pop too many */

  if (flag_mri)
    {
      while (! is_end_of_line[(unsigned char) *input_line_pointer])
	++input_line_pointer;
    }

  demand_empty_rest_of_line ();
}

void
s_else (int arg ATTRIBUTE_UNUSED)
{
  if (current_cframe == NULL)
    {
      as_bad (_("\".else\" without matching \".if\""));
    }
  else if (current_cframe->else_seen)
    {
      as_bad (_("duplicate \".else\""));
      as_bad_where (current_cframe->else_file_line.file,
		    current_cframe->else_file_line.line,
		    _("here is the previous \".else\""));
      as_bad_where (current_cframe->if_file_line.file,
		    current_cframe->if_file_line.line,
		    _("here is the previous \".if\""));
    }
  else
    {
      current_cframe->else_file_line.file
       	= as_where (&current_cframe->else_file_line.line);

      current_cframe->ignoring =
	current_cframe->dead_tree | !current_cframe->ignoring;

      if (LISTING_SKIP_COND ()
	  && (current_cframe->previous_cframe == NULL
	      || ! current_cframe->previous_cframe->ignoring))
	{
	  if (! current_cframe->ignoring)
	    listing_list (1);
	  else
	    listing_list (2);
	}

      current_cframe->else_seen = 1;
    }

  if (flag_mri)
    {
      while (! is_end_of_line[(unsigned char) *input_line_pointer])
	++input_line_pointer;
    }

  demand_empty_rest_of_line ();
}

void
s_ifeqs (int arg)
{
  char *s1, *s2;
  int len1, len2;
  int res;
  struct conditional_frame cframe;

  s1 = demand_copy_C_string (&len1);

  SKIP_WHITESPACE ();
  if (*input_line_pointer != ',')
    {
      as_bad (_(".ifeqs syntax error"));
      ignore_rest_of_line ();
      return;
    }

  ++input_line_pointer;

  s2 = demand_copy_C_string (&len2);

  res = len1 == len2 && strncmp (s1, s2, len1) == 0;

  initialize_cframe (&cframe);
  cframe.ignoring = cframe.dead_tree || ! (res ^ arg);
  current_cframe = ((struct conditional_frame *)
		    obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));

  if (LISTING_SKIP_COND ()
      && cframe.ignoring
      && (cframe.previous_cframe == NULL
	  || ! cframe.previous_cframe->ignoring))
    listing_list (2);

  demand_empty_rest_of_line ();
}

int
ignore_input (void)
{
  char *s;

  s = input_line_pointer;

  if (NO_PSEUDO_DOT || flag_m68k_mri)
    {
      if (s[-1] != '.')
	--s;
    }
  else
    {
      if (s[-1] != '.')
	return (current_cframe != NULL) && (current_cframe->ignoring);
    }

  /* We cannot ignore certain pseudo ops.  */
  if (((s[0] == 'i'
	|| s[0] == 'I')
       && (!strncasecmp (s, "if", 2)
	   || !strncasecmp (s, "ifdef", 5)
	   || !strncasecmp (s, "ifndef", 6)))
      || ((s[0] == 'e'
	   || s[0] == 'E')
	  && (!strncasecmp (s, "else", 4)
	      || !strncasecmp (s, "endif", 5)
	      || !strncasecmp (s, "endc", 4))))
    return 0;

  return (current_cframe != NULL) && (current_cframe->ignoring);
}

static void
initialize_cframe (struct conditional_frame *cframe)
{
  memset (cframe, 0, sizeof (*cframe));
  cframe->if_file_line.file
	    = as_where (&cframe->if_file_line.line);
  cframe->previous_cframe = current_cframe;
  cframe->dead_tree = current_cframe != NULL && current_cframe->ignoring;
  cframe->macro_nest = macro_nest;
}

/* Give an error if a conditional is unterminated inside a macro or
   the assembly as a whole.  If NEST is non negative, we are being
   called because of the end of a macro expansion.  If NEST is
   negative, we are being called at the of the input files.  */

void
cond_finish_check (int nest)
{
  if (current_cframe != NULL && current_cframe->macro_nest >= nest)
    {
      if (nest >= 0)
	as_bad (_("end of macro inside conditional"));
      else
	as_bad (_("end of file inside conditional"));
      as_bad_where (current_cframe->if_file_line.file,
		    current_cframe->if_file_line.line,
		    _("here is the start of the unterminated conditional"));
      if (current_cframe->else_seen)
	as_bad_where (current_cframe->else_file_line.file,
		      current_cframe->else_file_line.line,
		      _("here is the \"else\" of the unterminated conditional"));
    }
}

/* This function is called when we exit out of a macro.  We assume
   that any conditionals which began within the macro are correctly
   nested, and just pop them off the stack.  */

void
cond_exit_macro (int nest)
{
  while (current_cframe != NULL && current_cframe->macro_nest >= nest)
    {
      struct conditional_frame *hold;

      hold = current_cframe;
      current_cframe = current_cframe->previous_cframe;
      obstack_free (&cond_obstack, hold);
    }
}