X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=blobdiff_plain;f=gcc%2Fread-rtl.c;h=1402c5468371c0a90fbf63b59c65bca6bd2dbade;hp=377eb7e051e470ab4b3a48650603f14d5ceee845;hb=15c581919d5e1aa94eb0023c17d25497dee0caaf;hpb=aab2cf92f98dc58ac1bffb472b685b9b73f71529

diff --git a/gcc/read-rtl.c b/gcc/read-rtl.c
index 377eb7e051e..1402c546837 100644
--- a/gcc/read-rtl.c
+++ b/gcc/read-rtl.c
@@ -1,13 +1,13 @@
 /* RTL reader for GCC.
    Copyright (C) 1987, 1988, 1991, 1994, 1997, 1998, 1999, 2000, 2001, 2002,
-   2003
+   2003, 2004, 2005, 2007, 2008, 2010
    Free Software Foundation, Inc.
 
 This file is part of GCC.
 
 GCC 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
+Software Foundation; either version 3, or (at your option) any later
 version.
 
 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
@@ -16,345 +16,596 @@ 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 GCC; see the file COPYING.  If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA.  */
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
 
 #include "bconfig.h"
+
+/* Disable rtl checking; it conflicts with the iterator handling.  */
+#undef ENABLE_RTL_CHECKING
+
 #include "system.h"
 #include "coretypes.h"
 #include "tm.h"
 #include "rtl.h"
 #include "obstack.h"
 #include "hashtab.h"
+#include "read-md.h"
+#include "gensupport.h"
+
+/* One element in a singly-linked list of (integer, string) pairs.  */
+struct map_value {
+  struct map_value *next;
+  int number;
+  const char *string;
+};
+
+/* Maps an iterator or attribute name to a list of (integer, string) pairs.
+   The integers are mode or code values; the strings are either C conditions
+   or attribute values.  */
+struct mapping {
+  /* The name of the iterator or attribute.  */
+  const char *name;
+
+  /* The group (modes or codes) to which the iterator or attribute belongs.  */
+  struct iterator_group *group;
+
+  /* Gives a unique number to the attribute or iterator.  Numbers are
+     allocated consecutively, starting at 0.  */
+  int index;
+
+  /* The list of (integer, string) pairs.  */
+  struct map_value *values;
+};
+
+/* A structure for abstracting the common parts of code and mode iterators.  */
+struct iterator_group {
+  /* Tables of "mapping" structures, one for attributes and one for iterators.  */
+  htab_t attrs, iterators;
+
+  /* The number of "real" modes or codes (and by extension, the first
+     number available for use as an iterator placeholder).  */
+  int num_builtins;
+
+  /* Treat the given string as the name of a standard mode or code and
+     return its integer value.  */
+  int (*find_builtin) (const char *);
+
+  /* Return true if the given rtx uses the given mode or code.  */
+  bool (*uses_iterator_p) (rtx, int);
+
+  /* Make the given rtx use the given mode or code.  */
+  void (*apply_iterator) (rtx, int);
+};
+
+/* A structure used to pass data from read_rtx to apply_iterator_traverse
+   via htab_traverse.  */
+struct iterator_traverse_data {
+  /* Instruction queue.  */
+  rtx queue;
+  /* Attributes seen for modes.  */
+  struct map_value *mode_maps;
+  /* The last unknown attribute used as a mode.  */
+  const char *unknown_mode_attr;
+};
+
+/* If CODE is the number of a code iterator, return a real rtx code that
+   has the same format.  Return CODE otherwise.  */
+#define BELLWETHER_CODE(CODE) \
+  ((CODE) < NUM_RTX_CODE ? CODE : bellwether_codes[CODE - NUM_RTX_CODE])
+
+static int find_mode (const char *);
+static bool uses_mode_iterator_p (rtx, int);
+static void apply_mode_iterator (rtx, int);
+static int find_code (const char *);
+static bool uses_code_iterator_p (rtx, int);
+static void apply_code_iterator (rtx, int);
+static const char *apply_iterator_to_string (const char *, struct mapping *, int);
+static rtx apply_iterator_to_rtx (rtx, struct mapping *, int,
+				  struct map_value *, const char **);
+static bool uses_iterator_p (rtx, struct mapping *);
+static const char *add_condition_to_string (const char *, const char *);
+static void add_condition_to_rtx (rtx, const char *);
+static int apply_iterator_traverse (void **, void *);
+static struct mapping *add_mapping (struct iterator_group *, htab_t t,
+				    const char *);
+static struct map_value **add_map_value (struct map_value **,
+					 int, const char *);
+static void initialize_iterators (void);
+static void read_conditions (void);
+static void validate_const_int (const char *);
+static int find_iterator (struct iterator_group *, const char *);
+static struct mapping *read_mapping (struct iterator_group *, htab_t);
+static void check_code_iterator (struct mapping *);
+static rtx read_rtx_code (const char *, struct map_value **);
+static rtx read_nested_rtx (struct map_value **);
+static rtx read_rtx_variadic (struct map_value **, rtx);
+
+/* The mode and code iterator structures.  */
+static struct iterator_group modes, codes;
+
+/* Index I is the value of BELLWETHER_CODE (I + NUM_RTX_CODE).  */
+static enum rtx_code *bellwether_codes;
+
+/* Implementations of the iterator_group callbacks for modes.  */
 
-static htab_t md_constants;
-
-static void fatal_with_file_and_line (FILE *, const char *, ...)
-  ATTRIBUTE_PRINTF_2 ATTRIBUTE_NORETURN;
-static void fatal_expected_char (FILE *, int, int) ATTRIBUTE_NORETURN;
-static void read_name (char *, FILE *);
-static char *read_string (struct obstack *, FILE *, int);
-static char *read_quoted_string (struct obstack *, FILE *);
-static char *read_braced_string (struct obstack *, FILE *);
-static void read_escape (struct obstack *, FILE *);
-static hashval_t def_hash (const void *);
-static int def_name_eq_p (const void *, const void *);
-static void read_constants (FILE *infile, char *tmp_char);
-static void validate_const_int (FILE *, const char *);
+static int
+find_mode (const char *name)
+{
+  int i;
 
-/* Subroutines of read_rtx.  */
+  for (i = 0; i < NUM_MACHINE_MODES; i++)
+    if (strcmp (GET_MODE_NAME (i), name) == 0)
+      return i;
 
-/* The current line number for the file.  */
-int read_rtx_lineno = 1;
+  fatal_with_file_and_line ("unknown mode `%s'", name);
+}
 
-/* The filename for aborting with file and line.  */
-const char *read_rtx_filename = "<unknown>";
+static bool
+uses_mode_iterator_p (rtx x, int mode)
+{
+  return (int) GET_MODE (x) == mode;
+}
 
 static void
-fatal_with_file_and_line (FILE *infile, const char *msg, ...)
+apply_mode_iterator (rtx x, int mode)
 {
-  char context[64];
-  size_t i;
-  int c;
-  va_list ap;
-
-  va_start (ap, msg);
+  PUT_MODE (x, (enum machine_mode) mode);
+}
 
-  fprintf (stderr, "%s:%d: ", read_rtx_filename, read_rtx_lineno);
-  vfprintf (stderr, msg, ap);
-  putc ('\n', stderr);
+/* Implementations of the iterator_group callbacks for codes.  */
 
-  /* Gather some following context.  */
-  for (i = 0; i < sizeof (context)-1; ++i)
-    {
-      c = getc (infile);
-      if (c == EOF)
-	break;
-      if (c == '\r' || c == '\n')
-	break;
-      context[i] = c;
-    }
-  context[i] = '\0';
+static int
+find_code (const char *name)
+{
+  int i;
 
-  fprintf (stderr, "%s:%d: following context is `%s'\n",
-	   read_rtx_filename, read_rtx_lineno, context);
+  for (i = 0; i < NUM_RTX_CODE; i++)
+    if (strcmp (GET_RTX_NAME (i), name) == 0)
+      return i;
 
-  va_end (ap);
-  exit (1);
+  fatal_with_file_and_line ("unknown rtx code `%s'", name);
 }
 
-/* Dump code after printing a message.  Used when read_rtx finds
-   invalid data.  */
+static bool
+uses_code_iterator_p (rtx x, int code)
+{
+  return (int) GET_CODE (x) == code;
+}
 
 static void
-fatal_expected_char (FILE *infile, int expected_c, int actual_c)
+apply_code_iterator (rtx x, int code)
 {
-  fatal_with_file_and_line (infile, "expected character `%c', found `%c'",
-			    expected_c, actual_c);
+  PUT_CODE (x, (enum rtx_code) code);
 }
 
-/* Read chars from INFILE until a non-whitespace char
-   and return that.  Comments, both Lisp style and C style,
-   are treated as whitespace.
-   Tools such as genflags use this function.  */
+/* Map a code or mode attribute string P to the underlying string for
+   ITERATOR and VALUE.  */
 
-int
-read_skip_spaces (FILE *infile)
+static struct map_value *
+map_attr_string (const char *p, struct mapping *iterator, int value)
 {
-  int c;
-
-  while (1)
+  const char *attr;
+  struct mapping *m;
+  struct map_value *v;
+
+  /* If there's a "iterator:" prefix, check whether the iterator name matches.
+     Set ATTR to the start of the attribute name.  */
+  attr = strchr (p, ':');
+  if (attr == 0)
+    attr = p;
+  else
     {
-      c = getc (infile);
-      switch (c)
-	{
-	case '\n':
-	  read_rtx_lineno++;
-	  break;
+      if (strncmp (p, iterator->name, attr - p) != 0
+	  || iterator->name[attr - p] != 0)
+	return 0;
+      attr++;
+    }
 
-	case ' ': case '\t': case '\f': case '\r':
-	  break;
+  /* Find the attribute specification.  */
+  m = (struct mapping *) htab_find (iterator->group->attrs, &attr);
+  if (m == 0)
+    return 0;
 
-	case ';':
-	  do
-	    c = getc (infile);
-	  while (c != '\n' && c != EOF);
-	  read_rtx_lineno++;
-	  break;
+  /* Find the attribute value for VALUE.  */
+  for (v = m->values; v != 0; v = v->next)
+    if (v->number == value)
+      break;
 
-	case '/':
-	  {
-	    int prevc;
-	    c = getc (infile);
-	    if (c != '*')
-	      fatal_expected_char (infile, '*', c);
+  return v;
+}
 
-	    prevc = 0;
-	    while ((c = getc (infile)) && c != EOF)
-	      {
-		if (c == '\n')
-		   read_rtx_lineno++;
-	        else if (prevc == '*' && c == '/')
-		  break;
-	        prevc = c;
-	      }
-	  }
-	  break;
+/* Given an attribute string used as a machine mode, return an index
+   to store in the machine mode to be translated by
+   apply_iterator_to_rtx.  */
 
-	default:
-	  return c;
-	}
-    }
+static unsigned int
+mode_attr_index (struct map_value **mode_maps, const char *string)
+{
+  char *p;
+  struct map_value *mv;
+
+  /* Copy the attribute string into permanent storage, without the
+     angle brackets around it.  */
+  obstack_grow0 (&string_obstack, string + 1, strlen (string) - 2);
+  p = XOBFINISH (&string_obstack, char *);
+
+  mv = XNEW (struct map_value);
+  mv->number = *mode_maps == 0 ? 0 : (*mode_maps)->number + 1;
+  mv->string = p;
+  mv->next = *mode_maps;
+  *mode_maps = mv;
+
+  /* We return a code which we can map back into this string: the
+     number of machine modes + the number of mode iterators + the index
+     we just used.  */
+  return MAX_MACHINE_MODE + htab_elements (modes.iterators) + mv->number;
 }
 
-/* Read an rtx code name into the buffer STR[].
-   It is terminated by any of the punctuation chars of rtx printed syntax.  */
+/* Apply MODE_MAPS to the top level of X, expanding cases where an
+   attribute is used for a mode.  ITERATOR is the current iterator we are
+   expanding, and VALUE is the value to which we are expanding it.
+   This sets *UNKNOWN to true if we find a mode attribute which has not
+   yet been defined, and does not change it otherwise.  */
 
 static void
-read_name (char *str, FILE *infile)
+apply_mode_maps (rtx x, struct map_value *mode_maps, struct mapping *iterator,
+		 int value, const char **unknown)
 {
-  char *p;
-  int c;
+  unsigned int offset;
+  int indx;
+  struct map_value *pm;
 
-  c = read_skip_spaces (infile);
+  offset = MAX_MACHINE_MODE + htab_elements (modes.iterators);
+  if (GET_MODE (x) < offset)
+    return;
 
-  p = str;
-  while (1)
+  indx = GET_MODE (x) - offset;
+  for (pm = mode_maps; pm; pm = pm->next)
     {
-      if (c == ' ' || c == '\n' || c == '\t' || c == '\f' || c == '\r')
-	break;
-      if (c == ':' || c == ')' || c == ']' || c == '"' || c == '/'
-	  || c == '(' || c == '[')
+      if (pm->number == indx)
 	{
-	  ungetc (c, infile);
-	  break;
+	  struct map_value *v;
+
+	  v = map_attr_string (pm->string, iterator, value);
+	  if (v)
+	    PUT_MODE (x, (enum machine_mode) find_mode (v->string));
+	  else
+	    *unknown = pm->string;
+	  return;
 	}
-      *p++ = c;
-      c = getc (infile);
     }
-  if (p == str)
-    fatal_with_file_and_line (infile, "missing name or number");
-  if (c == '\n')
-    read_rtx_lineno++;
+}
 
-  *p = 0;
+/* Given that ITERATOR is being expanded as VALUE, apply the appropriate
+   string substitutions to STRING.  Return the new string if any changes
+   were needed, otherwise return STRING itself.  */
 
-  if (md_constants)
-    {
-      /* Do constant expansion.  */
-      struct md_constant *def;
+static const char *
+apply_iterator_to_string (const char *string, struct mapping *iterator, int value)
+{
+  char *base, *copy, *p, *start, *end;
+  struct map_value *v;
 
-      p = str;
-      do
-	{
-	  struct md_constant tmp_def;
-
-	  tmp_def.name = p;
-	  def = htab_find (md_constants, &tmp_def);
-	  if (def)
-	    p = def->value;
-	} while (def);
-      if (p != str)
-	strcpy (str, p);
+  if (string == 0)
+    return string;
+
+  base = p = copy = ASTRDUP (string);
+  while ((start = strchr (p, '<')) && (end = strchr (start, '>')))
+    {
+      p = start + 1;
+
+      *end = 0;
+      v = map_attr_string (p, iterator, value);
+      *end = '>';
+      if (v == 0)
+	continue;
+
+      /* Add everything between the last copied byte and the '<',
+	 then add in the attribute value.  */
+      obstack_grow (&string_obstack, base, start - base);
+      obstack_grow (&string_obstack, v->string, strlen (v->string));
+      base = end + 1;
     }
+  if (base != copy)
+    {
+      obstack_grow (&string_obstack, base, strlen (base) + 1);
+      copy = XOBFINISH (&string_obstack, char *);
+      copy_md_ptr_loc (copy, string);
+      return copy;
+    }
+  return string;
 }
 
-/* Subroutine of the string readers.  Handles backslash escapes.
-   Caller has read the backslash, but not placed it into the obstack.  */
-static void
-read_escape (struct obstack *ob, FILE *infile)
+/* Return a copy of ORIGINAL in which all uses of ITERATOR have been
+   replaced by VALUE.  MODE_MAPS holds information about attribute
+   strings used for modes.  This sets *UNKNOWN_MODE_ATTR to the value of
+   an unknown mode attribute, and does not change it otherwise.  */
+
+static rtx
+apply_iterator_to_rtx (rtx original, struct mapping *iterator, int value,
+		       struct map_value *mode_maps,
+		       const char **unknown_mode_attr)
+{
+  struct iterator_group *group;
+  const char *format_ptr;
+  int i, j;
+  rtx x;
+  enum rtx_code bellwether_code;
+
+  if (original == 0)
+    return original;
+
+  /* Create a shallow copy of ORIGINAL.  */
+  bellwether_code = BELLWETHER_CODE (GET_CODE (original));
+  x = rtx_alloc (bellwether_code);
+  memcpy (x, original, RTX_CODE_SIZE (bellwether_code));
+
+  /* Change the mode or code itself.  */
+  group = iterator->group;
+  if (group->uses_iterator_p (x, iterator->index + group->num_builtins))
+    group->apply_iterator (x, value);
+
+  if (mode_maps)
+    apply_mode_maps (x, mode_maps, iterator, value, unknown_mode_attr);
+
+  /* Change each string and recursively change each rtx.  */
+  format_ptr = GET_RTX_FORMAT (bellwether_code);
+  for (i = 0; format_ptr[i] != 0; i++)
+    switch (format_ptr[i])
+      {
+      case 'T':
+	XTMPL (x, i) = apply_iterator_to_string (XTMPL (x, i), iterator, value);
+	break;
+
+      case 'S':
+      case 's':
+	XSTR (x, i) = apply_iterator_to_string (XSTR (x, i), iterator, value);
+	break;
+
+      case 'e':
+	XEXP (x, i) = apply_iterator_to_rtx (XEXP (x, i), iterator, value,
+					     mode_maps, unknown_mode_attr);
+	break;
+
+      case 'V':
+      case 'E':
+	if (XVEC (original, i))
+	  {
+	    XVEC (x, i) = rtvec_alloc (XVECLEN (original, i));
+	    for (j = 0; j < XVECLEN (x, i); j++)
+	      XVECEXP (x, i, j) = apply_iterator_to_rtx (XVECEXP (original, i, j),
+							 iterator, value, mode_maps,
+							 unknown_mode_attr);
+	  }
+	break;
+
+      default:
+	break;
+      }
+  return x;
+}
+
+/* Return true if X (or some subexpression of X) uses iterator ITERATOR.  */
+
+static bool
+uses_iterator_p (rtx x, struct mapping *iterator)
 {
-  int c = getc (infile);
+  struct iterator_group *group;
+  const char *format_ptr;
+  int i, j;
+
+  if (x == 0)
+    return false;
 
-  switch (c)
+  group = iterator->group;
+  if (group->uses_iterator_p (x, iterator->index + group->num_builtins))
+    return true;
+
+  format_ptr = GET_RTX_FORMAT (BELLWETHER_CODE (GET_CODE (x)));
+  for (i = 0; format_ptr[i] != 0; i++)
+    switch (format_ptr[i])
+      {
+      case 'e':
+	if (uses_iterator_p (XEXP (x, i), iterator))
+	  return true;
+	break;
+
+      case 'V':
+      case 'E':
+	if (XVEC (x, i))
+	  for (j = 0; j < XVECLEN (x, i); j++)
+	    if (uses_iterator_p (XVECEXP (x, i, j), iterator))
+	      return true;
+	break;
+
+      default:
+	break;
+      }
+  return false;
+}
+
+/* Return a condition that must satisfy both ORIGINAL and EXTRA.  If ORIGINAL
+   has the form "&& ..." (as used in define_insn_and_splits), assume that
+   EXTRA is already satisfied.  Empty strings are treated like "true".  */
+
+static const char *
+add_condition_to_string (const char *original, const char *extra)
+{
+  if (original != 0 && original[0] == '&' && original[1] == '&')
+    return original;
+  return join_c_conditions (original, extra);
+}
+
+/* Like add_condition, but applied to all conditions in rtx X.  */
+
+static void
+add_condition_to_rtx (rtx x, const char *extra)
+{
+  switch (GET_CODE (x))
     {
-      /* Backslash-newline is replaced by nothing, as in C.  */
-    case '\n':
-      read_rtx_lineno++;
-      return;
-
-      /* \" \' \\ are replaced by the second character.  */
-    case '\\':
-    case '"':
-    case '\'':
+    case DEFINE_INSN:
+    case DEFINE_EXPAND:
+      XSTR (x, 2) = add_condition_to_string (XSTR (x, 2), extra);
       break;
 
-      /* Standard C string escapes:
-	 \a \b \f \n \r \t \v
-	 \[0-7] \x
-	 all are passed through to the output string unmolested.
-	 In normal use these wind up in a string constant processed
-	 by the C compiler, which will translate them appropriately.
-	 We do not bother checking that \[0-7] are followed by up to
-	 two octal digits, or that \x is followed by N hex digits.
-	 \? \u \U are left out because they are not in traditional C.  */
-    case 'a': case 'b': case 'f': case 'n': case 'r': case 't': case 'v':
-    case '0': case '1': case '2': case '3': case '4': case '5': case '6':
-    case '7': case 'x':
-      obstack_1grow (ob, '\\');
+    case DEFINE_SPLIT:
+    case DEFINE_PEEPHOLE:
+    case DEFINE_PEEPHOLE2:
+    case DEFINE_COND_EXEC:
+      XSTR (x, 1) = add_condition_to_string (XSTR (x, 1), extra);
       break;
 
-      /* \; makes stuff for a C string constant containing
-	 newline and tab.  */
-    case ';':
-      obstack_grow (ob, "\\n\\t", 4);
-      return;
+    case DEFINE_INSN_AND_SPLIT:
+      XSTR (x, 2) = add_condition_to_string (XSTR (x, 2), extra);
+      XSTR (x, 4) = add_condition_to_string (XSTR (x, 4), extra);
+      break;
 
-      /* pass anything else through, but issue a warning.  */
     default:
-      fprintf (stderr, "%s:%d: warning: unrecognized escape \\%c\n",
-	       read_rtx_filename, read_rtx_lineno, c);
-      obstack_1grow (ob, '\\');
       break;
     }
+}
 
-  obstack_1grow (ob, c);
+/* A htab_traverse callback.  Search the EXPR_LIST given by DATA
+   for rtxes that use the iterator in *SLOT.  Replace each such rtx
+   with a list of expansions.  */
+
+static int
+apply_iterator_traverse (void **slot, void *data)
+{
+  struct iterator_traverse_data *mtd = (struct iterator_traverse_data *) data;
+  struct mapping *iterator;
+  struct map_value *v;
+  rtx elem, new_elem, original, x;
+
+  iterator = (struct mapping *) *slot;
+  for (elem = mtd->queue; elem != 0; elem = XEXP (elem, 1))
+    if (uses_iterator_p (XEXP (elem, 0), iterator))
+      {
+	/* For each iterator we expand, we set UNKNOWN_MODE_ATTR to NULL.
+	   If apply_iterator_rtx finds an unknown attribute for a mode,
+	   it will set it to the attribute.  We want to know whether
+	   the attribute is unknown after we have expanded all
+	   possible iterators, so setting it to NULL here gives us the
+	   right result when the hash table traversal is complete.  */
+	mtd->unknown_mode_attr = NULL;
+
+	original = XEXP (elem, 0);
+	for (v = iterator->values; v != 0; v = v->next)
+	  {
+	    x = apply_iterator_to_rtx (original, iterator, v->number,
+				       mtd->mode_maps,
+				       &mtd->unknown_mode_attr);
+	    add_condition_to_rtx (x, v->string);
+	    if (v != iterator->values)
+	      {
+		/* Insert a new EXPR_LIST node after ELEM and put the
+		   new expansion there.  */
+		new_elem = rtx_alloc (EXPR_LIST);
+		XEXP (new_elem, 1) = XEXP (elem, 1);
+		XEXP (elem, 1) = new_elem;
+		elem = new_elem;
+	      }
+	    XEXP (elem, 0) = x;
+	  }
+    }
+  return 1;
 }
 
+/* Add a new "mapping" structure to hashtable TABLE.  NAME is the name
+   of the mapping and GROUP is the group to which it belongs.  */
 
-/* Read a double-quoted string onto the obstack.  Caller has scanned
-   the leading quote.  */
-static char *
-read_quoted_string (struct obstack *ob, FILE *infile)
+static struct mapping *
+add_mapping (struct iterator_group *group, htab_t table, const char *name)
 {
-  int c;
+  struct mapping *m;
+  void **slot;
 
-  while (1)
-    {
-      c = getc (infile); /* Read the string  */
-      if (c == '\n')
-	read_rtx_lineno++;
-      else if (c == '\\')
-	{
-	  read_escape (ob, infile);
-	  continue;
-	}
-      else if (c == '"')
-	break;
+  m = XNEW (struct mapping);
+  m->name = xstrdup (name);
+  m->group = group;
+  m->index = htab_elements (table);
+  m->values = 0;
 
-      obstack_1grow (ob, c);
-    }
+  slot = htab_find_slot (table, m, INSERT);
+  if (*slot != 0)
+    fatal_with_file_and_line ("`%s' already defined", name);
 
-  obstack_1grow (ob, 0);
-  return obstack_finish (ob);
+  *slot = m;
+  return m;
 }
 
-/* Read a braced string (a la Tcl) onto the obstack.  Caller has
-   scanned the leading brace.  Note that unlike quoted strings,
-   the outermost braces _are_ included in the string constant.  */
-static char *
-read_braced_string (struct obstack *ob, FILE *infile)
-{
-  int c;
-  int brace_depth = 1;  /* caller-processed */
-  unsigned long starting_read_rtx_lineno = read_rtx_lineno;
+/* Add the pair (NUMBER, STRING) to a list of map_value structures.
+   END_PTR points to the current null terminator for the list; return
+   a pointer the new null terminator.  */
 
-  obstack_1grow (ob, '{');
-  while (brace_depth)
-    {
-      c = getc (infile); /* Read the string  */
-
-      if (c == '\n')
-	read_rtx_lineno++;
-      else if (c == '{')
-	brace_depth++;
-      else if (c == '}')
-	brace_depth--;
-      else if (c == '\\')
-	{
-	  read_escape (ob, infile);
-	  continue;
-	}
-      else if (c == EOF)
-	fatal_with_file_and_line
-	  (infile, "missing closing } for opening brace on line %lu",
-	   starting_read_rtx_lineno);
+static struct map_value **
+add_map_value (struct map_value **end_ptr, int number, const char *string)
+{
+  struct map_value *value;
 
-      obstack_1grow (ob, c);
-    }
+  value = XNEW (struct map_value);
+  value->next = 0;
+  value->number = number;
+  value->string = string;
 
-  obstack_1grow (ob, 0);
-  return obstack_finish (ob);
+  *end_ptr = value;
+  return &value->next;
 }
 
-/* Read some kind of string constant.  This is the high-level routine
-   used by read_rtx.  It handles surrounding parentheses, leading star,
-   and dispatch to the appropriate string constant reader.  */
+/* Do one-time initialization of the mode and code attributes.  */
 
-static char *
-read_string (struct obstack *ob, FILE *infile, int star_if_braced)
+static void
+initialize_iterators (void)
 {
-  char *stringbuf;
-  int saw_paren = 0;
-  int c;
-
-  c = read_skip_spaces (infile);
-  if (c == '(')
+  struct mapping *lower, *upper;
+  struct map_value **lower_ptr, **upper_ptr;
+  char *copy, *p;
+  int i;
+
+  modes.attrs = htab_create (13, leading_string_hash, leading_string_eq_p, 0);
+  modes.iterators = htab_create (13, leading_string_hash,
+				 leading_string_eq_p, 0);
+  modes.num_builtins = MAX_MACHINE_MODE;
+  modes.find_builtin = find_mode;
+  modes.uses_iterator_p = uses_mode_iterator_p;
+  modes.apply_iterator = apply_mode_iterator;
+
+  codes.attrs = htab_create (13, leading_string_hash, leading_string_eq_p, 0);
+  codes.iterators = htab_create (13, leading_string_hash,
+				 leading_string_eq_p, 0);
+  codes.num_builtins = NUM_RTX_CODE;
+  codes.find_builtin = find_code;
+  codes.uses_iterator_p = uses_code_iterator_p;
+  codes.apply_iterator = apply_code_iterator;
+
+  lower = add_mapping (&modes, modes.attrs, "mode");
+  upper = add_mapping (&modes, modes.attrs, "MODE");
+  lower_ptr = &lower->values;
+  upper_ptr = &upper->values;
+  for (i = 0; i < MAX_MACHINE_MODE; i++)
     {
-      saw_paren = 1;
-      c = read_skip_spaces (infile);
-    }
+      copy = xstrdup (GET_MODE_NAME (i));
+      for (p = copy; *p != 0; p++)
+	*p = TOLOWER (*p);
 
-  if (c == '"')
-    stringbuf = read_quoted_string (ob, infile);
-  else if (c == '{')
-    {
-      if (star_if_braced)
-	obstack_1grow (ob, '*');
-      stringbuf = read_braced_string (ob, infile);
+      upper_ptr = add_map_value (upper_ptr, i, GET_MODE_NAME (i));
+      lower_ptr = add_map_value (lower_ptr, i, copy);
     }
-  else
-    fatal_with_file_and_line (infile, "expected `\"' or `{', found `%c'", c);
 
-  if (saw_paren)
+  lower = add_mapping (&codes, codes.attrs, "code");
+  upper = add_mapping (&codes, codes.attrs, "CODE");
+  lower_ptr = &lower->values;
+  upper_ptr = &upper->values;
+  for (i = 0; i < NUM_RTX_CODE; i++)
     {
-      c = read_skip_spaces (infile);
-      if (c != ')')
-	fatal_expected_char (infile, ')', c);
-    }
+      copy = xstrdup (GET_RTX_NAME (i));
+      for (p = copy; *p != 0; p++)
+	*p = TOUPPER (*p);
 
-  return stringbuf;
+      lower_ptr = add_map_value (lower_ptr, i, GET_RTX_NAME (i));
+      upper_ptr = add_map_value (upper_ptr, i, copy);
+    }
 }
 
 /* Provide a version of a function to read a long long if the system does
@@ -394,95 +645,57 @@ atoll (const char *p)
   return tmp_wide;
 }
 #endif
-
-/* Given a constant definition, return a hash code for its name.  */
-static hashval_t
-def_hash (const void *def)
-{
-  unsigned result, i;
-  const char *string = ((const struct md_constant *) def)->name;
-
-  for (result = i = 0;*string++ != '\0'; i++)
-    result += ((unsigned char) *string << (i % CHAR_BIT));
-  return result;
-}
-
-/* Given two constant definitions, return true if they have the same name.  */
-static int
-def_name_eq_p (const void *def1, const void *def2)
-{
-  return ! strcmp (((const struct md_constant *) def1)->name,
-		   ((const struct md_constant *) def2)->name);
-}
-
-/* INFILE is a FILE pointer to read text from.  TMP_CHAR is a buffer suitable
-   to read a name or number into.  Process a define_constants directive,
-   starting with the optional space after the "define_constants".  */
+
+/* Process a define_conditions directive, starting with the optional
+   space after the "define_conditions".  The directive looks like this:
+
+     (define_conditions [
+        (number "string")
+        (number "string")
+        ...
+     ])
+
+   It's not intended to appear in machine descriptions.  It is
+   generated by (the program generated by) genconditions.c, and
+   slipped in at the beginning of the sequence of MD files read by
+   most of the other generators.  */
 static void
-read_constants (FILE *infile, char *tmp_char)
+read_conditions (void)
 {
   int c;
-  htab_t defs;
 
-  c = read_skip_spaces (infile);
+  c = read_skip_spaces ();
   if (c != '[')
-    fatal_expected_char (infile, '[', c);
-  defs = md_constants;
-  if (! defs)
-    defs = htab_create (32, def_hash, def_name_eq_p, (htab_del) 0);
-  /* Disable constant expansion during definition processing.  */
-  md_constants = 0;
-  while ( (c = read_skip_spaces (infile)) != ']')
+    fatal_expected_char ('[', c);
+
+  while ( (c = read_skip_spaces ()) != ']')
     {
-      struct md_constant *def;
-      void **entry_ptr;
+      struct md_name name;
+      char *expr;
+      int value;
 
       if (c != '(')
-	fatal_expected_char (infile, '(', c);
-      def = xmalloc (sizeof (struct md_constant));
-      def->name = tmp_char;
-      read_name (tmp_char, infile);
-      entry_ptr = htab_find_slot (defs, def, TRUE);
-      if (! *entry_ptr)
-	def->name = xstrdup (tmp_char);
-      c = read_skip_spaces (infile);
-      ungetc (c, infile);
-      read_name (tmp_char, infile);
-      if (! *entry_ptr)
-	{
-	  def->value = xstrdup (tmp_char);
-	  *entry_ptr = def;
-	}
-      else
-	{
-	  def = *entry_ptr;
-	  if (strcmp (def->value, tmp_char))
-	    fatal_with_file_and_line (infile,
-				      "redefinition of %s, was %s, now %s",
-				      def->name, def->value, tmp_char);
-	}
-      c = read_skip_spaces (infile);
+	fatal_expected_char ('(', c);
+
+      read_name (&name);
+      validate_const_int (name.string);
+      value = atoi (name.string);
+
+      c = read_skip_spaces ();
+      if (c != '"')
+	fatal_expected_char ('"', c);
+      expr = read_quoted_string ();
+
+      c = read_skip_spaces ();
       if (c != ')')
-	fatal_expected_char (infile, ')', c);
-    }
-  md_constants = defs;
-  c = read_skip_spaces (infile);
-  if (c != ')')
-    fatal_expected_char (infile, ')', c);
-}
+	fatal_expected_char (')', c);
 
-/* For every constant definition, call CALLBACK with two arguments:
-   a pointer a pointer to the constant definition and INFO.
-   Stops when CALLBACK returns zero.  */
-void
-traverse_md_constants (htab_trav callback, void *info)
-{
-  if (md_constants)
-    htab_traverse (md_constants, callback, info);
+      add_c_test (expr, value);
+    }
 }
 
 static void
-validate_const_int (FILE *infile, const char *string)
+validate_const_int (const char *string)
 {
   const char *cp;
   int valid = 1;
@@ -498,104 +711,218 @@ validate_const_int (FILE *infile, const char *string)
     if (! ISDIGIT (*cp))
       valid = 0;
   if (!valid)
-    fatal_with_file_and_line (infile, "invalid decimal constant \"%s\"\n", string);
+    fatal_with_file_and_line ("invalid decimal constant \"%s\"\n", string);
 }
 
-/* Read an rtx in printed representation from INFILE
-   and return an actual rtx in core constructed accordingly.
-   read_rtx is not used in the compiler proper, but rather in
-   the utilities gen*.c that construct C code from machine descriptions.  */
+/* Search GROUP for a mode or code called NAME and return its numerical
+   identifier.  */
 
-rtx
-read_rtx (FILE *infile)
+static int
+find_iterator (struct iterator_group *group, const char *name)
 {
-  int i, j;
-  RTX_CODE tmp_code;
-  const char *format_ptr;
-  /* tmp_char is a buffer used for reading decimal integers
-     and names of rtx types and machine modes.
-     Therefore, 256 must be enough.  */
-  char tmp_char[256];
-  rtx return_rtx;
-  int c;
-  int tmp_int;
-  HOST_WIDE_INT tmp_wide;
+  struct mapping *m;
 
-  /* Obstack used for allocating RTL objects.  */
-  static struct obstack rtl_obstack;
-  static int initialized;
+  m = (struct mapping *) htab_find (group->iterators, &name);
+  if (m != 0)
+    return m->index + group->num_builtins;
+  return group->find_builtin (name);
+}
 
-  /* Linked list structure for making RTXs: */
-  struct rtx_list
-    {
-      struct rtx_list *next;
-      rtx value;		/* Value of this node.  */
-    };
+/* Finish reading a declaration of the form:
 
-  if (!initialized) {
-    obstack_init (&rtl_obstack);
-    initialized = 1;
-  }
+       (define... <name> [<value1> ... <valuen>])
 
-again:
-  c = read_skip_spaces (infile); /* Should be open paren.  */
-  if (c != '(')
-    fatal_expected_char (infile, '(', c);
+   from the MD file, where each <valuei> is either a bare symbol name or a
+   "(<name> <string>)" pair.  The "(define..." part has already been read.
 
-  read_name (tmp_char, infile);
+   Represent the declaration as a "mapping" structure; add it to TABLE
+   (which belongs to GROUP) and return it.  */
+
+static struct mapping *
+read_mapping (struct iterator_group *group, htab_t table)
+{
+  struct md_name name;
+  struct mapping *m;
+  struct map_value **end_ptr;
+  const char *string;
+  int number, c;
 
-  tmp_code = UNKNOWN;
+  /* Read the mapping name and create a structure for it.  */
+  read_name (&name);
+  m = add_mapping (group, table, name.string);
 
-  if (! strcmp (tmp_char, "define_constants"))
+  c = read_skip_spaces ();
+  if (c != '[')
+    fatal_expected_char ('[', c);
+
+  /* Read each value.  */
+  end_ptr = &m->values;
+  c = read_skip_spaces ();
+  do
     {
-      read_constants (infile, tmp_char);
-      goto again;
+      if (c != '(')
+	{
+	  /* A bare symbol name that is implicitly paired to an
+	     empty string.  */
+	  unread_char (c);
+	  read_name (&name);
+	  string = "";
+	}
+      else
+	{
+	  /* A "(name string)" pair.  */
+	  read_name (&name);
+	  string = read_string (false);
+	  c = read_skip_spaces ();
+	  if (c != ')')
+	    fatal_expected_char (')', c);
+	}
+      number = group->find_builtin (name.string);
+      end_ptr = add_map_value (end_ptr, number, string);
+      c = read_skip_spaces ();
     }
-  for (i = 0; i < NUM_RTX_CODE; i++)
-    if (! strcmp (tmp_char, GET_RTX_NAME (i)))
-      {
-	tmp_code = (RTX_CODE) i;	/* get value for name */
-	break;
-      }
+  while (c != ']');
+
+  return m;
+}
+
+/* Check newly-created code iterator ITERATOR to see whether every code has the
+   same format.  Initialize the iterator's entry in bellwether_codes.  */
+
+static void
+check_code_iterator (struct mapping *iterator)
+{
+  struct map_value *v;
+  enum rtx_code bellwether;
+
+  bellwether = (enum rtx_code) iterator->values->number;
+  for (v = iterator->values->next; v != 0; v = v->next)
+    if (strcmp (GET_RTX_FORMAT (bellwether), GET_RTX_FORMAT (v->number)) != 0)
+      fatal_with_file_and_line ("code iterator `%s' combines "
+				"different rtx formats", iterator->name);
+
+  bellwether_codes = XRESIZEVEC (enum rtx_code, bellwether_codes,
+				 iterator->index + 1);
+  bellwether_codes[iterator->index] = bellwether;
+}
 
-  if (tmp_code == UNKNOWN)
-    fatal_with_file_and_line (infile, "unknown rtx code `%s'", tmp_char);
+/* Read an rtx-related declaration from the MD file, given that it
+   starts with directive name RTX_NAME.  Return true if it expands to
+   one or more rtxes (as defined by rtx.def).  When returning true,
+   store the list of rtxes as an EXPR_LIST in *X.  */
+
+bool
+read_rtx (const char *rtx_name, rtx *x)
+{
+  static rtx queue_head;
+  struct map_value *mode_maps;
+  struct iterator_traverse_data mtd;
 
-  /* (NIL) stands for an expression that isn't there.  */
-  if (tmp_code == NIL)
+  /* Do one-time initialization.  */
+  if (queue_head == 0)
     {
-      /* Discard the closeparen.  */
-      while ((c = getc (infile)) && c != ')')
-	;
+      initialize_iterators ();
+      queue_head = rtx_alloc (EXPR_LIST);
+    }
 
-      return 0;
+  /* Handle various rtx-related declarations that aren't themselves
+     encoded as rtxes.  */
+  if (strcmp (rtx_name, "define_conditions") == 0)
+    {
+      read_conditions ();
+      return false;
+    }
+  if (strcmp (rtx_name, "define_mode_attr") == 0)
+    {
+      read_mapping (&modes, modes.attrs);
+      return false;
     }
+  if (strcmp (rtx_name, "define_mode_iterator") == 0)
+    {
+      read_mapping (&modes, modes.iterators);
+      return false;
+    }
+  if (strcmp (rtx_name, "define_code_attr") == 0)
+    {
+      read_mapping (&codes, codes.attrs);
+      return false;
+    }
+  if (strcmp (rtx_name, "define_code_iterator") == 0)
+    {
+      check_code_iterator (read_mapping (&codes, codes.iterators));
+      return false;
+    }
+
+  mode_maps = 0;
+  XEXP (queue_head, 0) = read_rtx_code (rtx_name, &mode_maps);
+  XEXP (queue_head, 1) = 0;
+
+  mtd.queue = queue_head;
+  mtd.mode_maps = mode_maps;
+  mtd.unknown_mode_attr = mode_maps ? mode_maps->string : NULL;
+  htab_traverse (modes.iterators, apply_iterator_traverse, &mtd);
+  htab_traverse (codes.iterators, apply_iterator_traverse, &mtd);
+  if (mtd.unknown_mode_attr)
+    fatal_with_file_and_line ("undefined attribute '%s' used for mode",
+			      mtd.unknown_mode_attr);
+
+  *x = queue_head;
+  return true;
+}
+
+/* Subroutine of read_rtx and read_nested_rtx.  CODE_NAME is the name of
+   either an rtx code or a code iterator.  Parse the rest of the rtx and
+   return it.  MODE_MAPS is as for iterator_traverse_data.  */
+
+static rtx
+read_rtx_code (const char *code_name, struct map_value **mode_maps)
+{
+  int i;
+  RTX_CODE real_code, bellwether_code;
+  const char *format_ptr;
+  struct md_name name;
+  rtx return_rtx;
+  int c;
+  int tmp_int;
+  HOST_WIDE_INT tmp_wide;
+
+  /* Linked list structure for making RTXs: */
+  struct rtx_list
+    {
+      struct rtx_list *next;
+      rtx value;		/* Value of this node.  */
+    };
+
+  real_code = (enum rtx_code) find_iterator (&codes, code_name);
+  bellwether_code = BELLWETHER_CODE (real_code);
 
   /* If we end up with an insn expression then we free this space below.  */
-  return_rtx = rtx_alloc (tmp_code);
-  format_ptr = GET_RTX_FORMAT (GET_CODE (return_rtx));
+  return_rtx = rtx_alloc (bellwether_code);
+  format_ptr = GET_RTX_FORMAT (bellwether_code);
+  PUT_CODE (return_rtx, real_code);
 
   /* If what follows is `: mode ', read it and
      store the mode in the rtx.  */
 
-  i = read_skip_spaces (infile);
+  i = read_skip_spaces ();
   if (i == ':')
     {
-      read_name (tmp_char, infile);
-      for (j = 0; j < NUM_MACHINE_MODES; j++)
-	if (! strcmp (GET_MODE_NAME (j), tmp_char))
-	  break;
+      unsigned int mode;
 
-      if (j == MAX_MACHINE_MODE)
-	fatal_with_file_and_line (infile, "unknown mode `%s'", tmp_char);
-
-      PUT_MODE (return_rtx, (enum machine_mode) j);
+      read_name (&name);
+      if (name.string[0] != '<' || name.string[strlen (name.string) - 1] != '>')
+	mode = find_iterator (&modes, name.string);
+      else
+	mode = mode_attr_index (mode_maps, name.string);
+      PUT_MODE (return_rtx, (enum machine_mode) mode);
+      if (GET_MODE (return_rtx) != mode)
+	fatal_with_file_and_line ("mode too large");
     }
   else
-    ungetc (i, infile);
+    unread_char (i);
 
-  for (i = 0; i < GET_RTX_LENGTH (GET_CODE (return_rtx)); i++)
-    switch (*format_ptr++)
+  for (i = 0; format_ptr[i] != 0; i++)
+    switch (format_ptr[i])
       {
 	/* 0 means a field for internal use only.
 	   Don't expect it to be present in the input.  */
@@ -604,14 +931,14 @@ again:
 
       case 'e':
       case 'u':
-	XEXP (return_rtx, i) = read_rtx (infile);
+	XEXP (return_rtx, i) = read_nested_rtx (mode_maps);
 	break;
 
       case 'V':
 	/* 'V' is an optional vector: if a closeparen follows,
 	   just store NULL for this element.  */
-	c = read_skip_spaces (infile);
-	ungetc (c, infile);
+	c = read_skip_spaces ();
+	unread_char (c);
 	if (c == ')')
 	  {
 	    XVEC (return_rtx, i) = 0;
@@ -626,17 +953,19 @@ again:
 	  int list_counter = 0;
 	  rtvec return_vec = NULL_RTVEC;
 
-	  c = read_skip_spaces (infile);
+	  c = read_skip_spaces ();
 	  if (c != '[')
-	    fatal_expected_char (infile, '[', c);
+	    fatal_expected_char ('[', c);
 
 	  /* Add expressions to a list, while keeping a count.  */
 	  obstack_init (&vector_stack);
-	  while ((c = read_skip_spaces (infile)) && c != ']')
+	  while ((c = read_skip_spaces ()) && c != ']')
 	    {
-	      ungetc (c, infile);
+	      if (c == EOF)
+		fatal_expected_char (']', c);
+	      unread_char (c);
 	      list_counter++;
-	      obstack_ptr_grow (&vector_stack, read_rtx (infile));
+	      obstack_ptr_grow (&vector_stack, read_nested_rtx (mode_maps));
 	    }
 	  if (list_counter > 0)
 	    {
@@ -644,6 +973,8 @@ again:
 	      memcpy (&return_vec->elem[0], obstack_finish (&vector_stack),
 		      list_counter * sizeof (rtx));
 	    }
+	  else if (format_ptr[i] == 'E')
+	    fatal_with_file_and_line ("vector must have at least one element");
 	  XVEC (return_rtx, i) = return_vec;
 	  obstack_free (&vector_stack, NULL);
 	  /* close bracket gotten */
@@ -651,28 +982,30 @@ again:
 	break;
 
       case 'S':
-	/* 'S' is an optional string: if a closeparen follows,
-	   just store NULL for this element.  */
-	c = read_skip_spaces (infile);
-	ungetc (c, infile);
-	if (c == ')')
-	  {
-	    XSTR (return_rtx, i) = 0;
-	    break;
-	  }
-
       case 'T':
       case 's':
 	{
 	  char *stringbuf;
+	  int star_if_braced;
+
+	  c = read_skip_spaces ();
+	  unread_char (c);
+	  if (c == ')')
+	    {
+	      /* 'S' fields are optional and should be NULL if no string
+		 was given.  Also allow normal 's' and 'T' strings to be
+		 omitted, treating them in the same way as empty strings.  */
+	      XSTR (return_rtx, i) = (format_ptr[i] == 'S' ? NULL : "");
+	      break;
+	    }
 
 	  /* The output template slot of a DEFINE_INSN,
 	     DEFINE_INSN_AND_SPLIT, or DEFINE_PEEPHOLE automatically
 	     gets a star inserted as its first character, if it is
 	     written with a brace block instead of a string constant.  */
-	  int star_if_braced = (format_ptr[-1] == 'T');
+	  star_if_braced = (format_ptr[i] == 'T');
 
-	  stringbuf = read_string (&rtl_obstack, infile, star_if_braced);
+	  stringbuf = read_string (star_if_braced);
 
 	  /* For insn patterns, we want to provide a default name
 	     based on the file and line, like "*foo.md:12", if the
@@ -684,16 +1017,16 @@ again:
 		  || GET_CODE (return_rtx) == DEFINE_INSN_AND_SPLIT))
 	    {
 	      char line_name[20];
-	      const char *fn = (read_rtx_filename ? read_rtx_filename : "rtx");
+	      const char *fn = (read_md_filename ? read_md_filename : "rtx");
 	      const char *slash;
 	      for (slash = fn; *slash; slash ++)
 		if (*slash == '/' || *slash == '\\' || *slash == ':')
 		  fn = slash + 1;
-	      obstack_1grow (&rtl_obstack, '*');
-	      obstack_grow (&rtl_obstack, fn, strlen (fn));
-	      sprintf (line_name, ":%d", read_rtx_lineno);
-	      obstack_grow (&rtl_obstack, line_name, strlen (line_name)+1);
-	      stringbuf = (char *) obstack_finish (&rtl_obstack);
+	      obstack_1grow (&string_obstack, '*');
+	      obstack_grow (&string_obstack, fn, strlen (fn));
+	      sprintf (line_name, ":%d", read_md_lineno);
+	      obstack_grow (&string_obstack, line_name, strlen (line_name)+1);
+	      stringbuf = XOBFINISH (&string_obstack, char *);
 	    }
 
 	  if (star_if_braced)
@@ -704,20 +1037,20 @@ again:
 	break;
 
       case 'w':
-	read_name (tmp_char, infile);
-	validate_const_int (infile, tmp_char);
+	read_name (&name);
+	validate_const_int (name.string);
 #if HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_INT
-	tmp_wide = atoi (tmp_char);
+	tmp_wide = atoi (name.string);
 #else
 #if HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_LONG
-	tmp_wide = atol (tmp_char);
+	tmp_wide = atol (name.string);
 #else
 	/* Prefer atoll over atoq, since the former is in the ISO C99 standard.
 	   But prefer not to use our hand-rolled function above either.  */
 #if defined(HAVE_ATOLL) || !defined(HAVE_ATOQ)
-	tmp_wide = atoll (tmp_char);
+	tmp_wide = atoll (name.string);
 #else
-	tmp_wide = atoq (tmp_char);
+	tmp_wide = atoq (name.string);
 #endif
 #endif
 #endif
@@ -726,23 +1059,82 @@ again:
 
       case 'i':
       case 'n':
-	read_name (tmp_char, infile);
-	validate_const_int (infile, tmp_char);
-	tmp_int = atoi (tmp_char);
+	read_name (&name);
+	validate_const_int (name.string);
+	tmp_int = atoi (name.string);
 	XINT (return_rtx, i) = tmp_int;
 	break;
 
       default:
-	fprintf (stderr,
-		 "switch format wrong in rtl.read_rtx(). format was: %c.\n",
-		 format_ptr[-1]);
-	fprintf (stderr, "\tfile position: %ld\n", ftell (infile));
-	abort ();
+	gcc_unreachable ();
       }
 
-  c = read_skip_spaces (infile);
+  c = read_skip_spaces ();
+  /* Syntactic sugar for AND and IOR, allowing Lisp-like
+     arbitrary number of arguments for them.  */
+  if (c == '('
+      && (GET_CODE (return_rtx) == AND
+	  || GET_CODE (return_rtx) == IOR))
+    return read_rtx_variadic (mode_maps, return_rtx);
+
+  unread_char (c);
+  return return_rtx;
+}
+
+/* Read a nested rtx construct from the MD file and return it.
+   MODE_MAPS is as for iterator_traverse_data.  */
+
+static rtx
+read_nested_rtx (struct map_value **mode_maps)
+{
+  struct md_name name;
+  int c;
+  rtx return_rtx;
+
+  c = read_skip_spaces ();
+  if (c != '(')
+    fatal_expected_char ('(', c);
+
+  read_name (&name);
+  if (strcmp (name.string, "nil") == 0)
+    return_rtx = NULL;
+  else
+    return_rtx = read_rtx_code (name.string, mode_maps);
+
+  c = read_skip_spaces ();
   if (c != ')')
-    fatal_expected_char (infile, ')', c);
+    fatal_expected_char (')', c);
 
   return return_rtx;
 }
+
+/* Mutually recursive subroutine of read_rtx which reads
+   (thing x1 x2 x3 ...) and produces RTL as if
+   (thing x1 (thing x2 (thing x3 ...)))  had been written.
+   When called, FORM is (thing x1 x2), and the file position
+   is just past the leading parenthesis of x3.  Only works
+   for THINGs which are dyadic expressions, e.g. AND, IOR.  */
+static rtx
+read_rtx_variadic (struct map_value **mode_maps, rtx form)
+{
+  char c = '(';
+  rtx p = form, q;
+
+  do
+    {
+      unread_char (c);
+
+      q = rtx_alloc (GET_CODE (p));
+      PUT_MODE (q, GET_MODE (p));
+
+      XEXP (q, 0) = XEXP (p, 1);
+      XEXP (q, 1) = read_nested_rtx (mode_maps);
+
+      XEXP (p, 1) = q;
+      p = q;
+      c = read_skip_spaces ();
+    }
+  while (c == '(');
+  unread_char (c);
+  return form;
+}