Extend hashed symbol dictionaries to work with Ada

This patch allows Ada to speed up symbol lookup by using the facilities
in dictionary.[ch] for hashed lookups.  First, we generalize dictionary
search to allow clients to specify any matching function compatible with
the hashing function. Next, we modify the hashing algorithm so that symbols
that wild-match a name hash to the same value.  Finally, we modify Ada
symbol lookup to use these facilities.

Because this patch touches on a hashing algorithm used by other
languages, I took the precaution of doing a speed test on a list of
about 12000 identifiers (repeatedly inserting all of them into a table
and then doing a lookup on a million names at random, thus testing the
speed of the hashing algorithm and how well it distributed names).
There was actually a slight speedup, probably as a result of open-
coding some of the tests in msymbol_hash_iw.  By design, the revised
hashing algorithm produces the same results as the original on most
"normal" C identifiers.

We considered augmenting the dictionary interface still further by allowing
different hashing algorithms for different dictionaries, based on the
(supposed) language of the symbols in that dictionary.  While this produced
better isolation of the changes to Ada programs, the additional flexibility
also complicated the dictionary interface.  I'd prefer to keep things
simple for now.

Tested w/o regressions on Linux i686.

ChangeLog:

	gdb/
	* ada-lang.c (ada_match_name): Use new API for wild_match.
	(wild_match): Change API to be consistent with that of strcmp_iw;
	return 0 for a match, and switch operand order.
	(full_match): New function.
	(ada_add_block_symbols): Use dict_iter_match_{first,next} for
	matching to allow use of hashing.
	* dictionary.c (struct dict_vector): Generalize iter_name_first,
	iter_name_next ot iter_match_first, iter_match_next.
	(iter_name_first_hashed): Replace with iter_match_first_hashed.
	(iter_name_next_hashed): Replace with iter_match_next_hashed.
	(iter_name_first_linear): Replace with iter_match_first_linear.
	(iter_name_next_linear): Replace with iter_match_next_linear.
	(dict_iter_name_first): Re-implement to use dict_iter_match_first.
	(dict_iter_name_next): Re-implement to use dict_iter_match_next.
	(dict_iter_match_first): New function.
	(dict_iter_match_next): New function.
	(dict_hash): New function.
	* dictionary.h (dict_iter_match_first, dict_iter_match_next): Declare.
	* psymtab.c (ada_lookup_partial_symbol): Use new wild_match API.

1 files changed, 130 insertions, 39 deletions

diff --git a/gdb/dictionary.c b/gdb/dictionary.c
index e1c2010..f3ac306 100644
--- a/gdb/dictionary.c
+++ b/gdb/dictionary.c
@@ -21,6 +21,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
+#include <ctype.h>
 #include "gdb_obstack.h"
 #include "symtab.h"
 #include "buildsym.h"
@@ -116,11 +117,15 @@ struct dict_vector
 				    struct dict_iterator *iterator);
   struct symbol *(*iterator_next) (struct dict_iterator *iterator);
   /* Functions to iterate over symbols with a given name.  */
-  struct symbol *(*iter_name_first) (const struct dictionary *dict,
+  struct symbol *(*iter_match_first) (const struct dictionary *dict,
 				     const char *name,
+				     int (*equiv) (const char *,
+						   const char *),
+				     struct dict_iterator *iterator);
+  struct symbol *(*iter_match_next) (const char *name,
+				     int (*equiv) (const char *,
+						   const char *),
 				     struct dict_iterator *iterator);
-  struct symbol *(*iter_name_next) (const char *name,
-				    struct dict_iterator *iterator);
   /* A size function, for maint print symtabs.  */
   int (*size) (const struct dictionary *dict);
 };
@@ -236,12 +241,18 @@ static struct symbol *iterator_first_hashed (const struct dictionary *dict,
 
 static struct symbol *iterator_next_hashed (struct dict_iterator *iterator);
 
-static struct symbol *iter_name_first_hashed (const struct dictionary *dict,
-					      const char *name,
+static struct symbol *iter_match_first_hashed (const struct dictionary *dict,
+					       const char *name,
+					       int (*compare) (const char *,
+							       const char *),
 					      struct dict_iterator *iterator);
 
-static struct symbol *iter_name_next_hashed (const char *name,
-					     struct dict_iterator *iterator);
+static struct symbol *iter_match_next_hashed (const char *name,
+					      int (*compare) (const char *,
+							      const char *),
+					      struct dict_iterator *iterator);
+
+static unsigned int dict_hash (const char *string);
 
 /* Functions only for DICT_HASHED.  */
 
@@ -264,12 +275,16 @@ static struct symbol *iterator_first_linear (const struct dictionary *dict,
 
 static struct symbol *iterator_next_linear (struct dict_iterator *iterator);
 
-static struct symbol *iter_name_first_linear (const struct dictionary *dict,
-					      const char *name,
-					      struct dict_iterator *iterator);
+static struct symbol *iter_match_first_linear (const struct dictionary *dict,
+					       const char *name,
+					       int (*compare) (const char *,
+							       const char *),
+					       struct dict_iterator *iterator);
 
-static struct symbol *iter_name_next_linear (const char *name,
-					     struct dict_iterator *iterator);
+static struct symbol *iter_match_next_linear (const char *name,
+					      int (*compare) (const char *,
+							      const char *),
+					      struct dict_iterator *iterator);
 
 static int size_linear (const struct dictionary *dict);
 
@@ -289,8 +304,8 @@ static const struct dict_vector dict_hashed_vector =
     add_symbol_nonexpandable,		/* add_symbol */
     iterator_first_hashed,		/* iterator_first */
     iterator_next_hashed,		/* iterator_next */
-    iter_name_first_hashed,		/* iter_name_first */
-    iter_name_next_hashed,		/* iter_name_next */
+    iter_match_first_hashed,		/* iter_name_first */
+    iter_match_next_hashed,		/* iter_name_next */
     size_hashed,			/* size */
   };
 
@@ -301,8 +316,8 @@ static const struct dict_vector dict_hashed_expandable_vector =
     add_symbol_hashed_expandable,	/* add_symbol */
     iterator_first_hashed,		/* iterator_first */
     iterator_next_hashed,		/* iterator_next */
-    iter_name_first_hashed,		/* iter_name_first */
-    iter_name_next_hashed,		/* iter_name_next */
+    iter_match_first_hashed,		/* iter_name_first */
+    iter_match_next_hashed,		/* iter_name_next */
     size_hashed_expandable,		/* size */
   };
 
@@ -313,8 +328,8 @@ static const struct dict_vector dict_linear_vector =
     add_symbol_nonexpandable,		/* add_symbol */
     iterator_first_linear,		/* iterator_first */
     iterator_next_linear,		/* iterator_next */
-    iter_name_first_linear,		/* iter_name_first */
-    iter_name_next_linear,		/* iter_name_next */
+    iter_match_first_linear,		/* iter_name_first */
+    iter_match_next_linear,		/* iter_name_next */
     size_linear,			/* size */
   };
 
@@ -325,8 +340,8 @@ static const struct dict_vector dict_linear_expandable_vector =
     add_symbol_linear_expandable,	/* add_symbol */
     iterator_first_linear,		/* iterator_first */
     iterator_next_linear,		/* iterator_next */
-    iter_name_first_linear,		/* iter_name_first */
-    iter_name_next_linear,		/* iter_name_next */
+    iter_match_first_linear,		/* iter_name_first */
+    iter_match_next_linear,		/* iter_name_next */
     size_linear,			/* size */
   };
 
@@ -516,14 +531,31 @@ dict_iter_name_first (const struct dictionary *dict,
 		      const char *name,
 		      struct dict_iterator *iterator)
 {
-  return (DICT_VECTOR (dict))->iter_name_first (dict, name, iterator);
+  return dict_iter_match_first (dict, name, strcmp_iw, iterator);
 }
 
 struct symbol *
 dict_iter_name_next (const char *name, struct dict_iterator *iterator)
 {
+  return dict_iter_match_next (name, strcmp_iw, iterator);
+}
+
+struct symbol *
+dict_iter_match_first (const struct dictionary *dict,
+		       const char *name,
+		       int (*compare) (const char *, const char *),
+		       struct dict_iterator *iterator)
+{
+  return (DICT_VECTOR (dict))->iter_match_first (dict, name, compare, iterator);
+}
+
+struct symbol *
+dict_iter_match_next (const char *name,
+		      int (*compare) (const char *, const char *),
+		      struct dict_iterator *iterator)
+{
   return (DICT_VECTOR (DICT_ITERATOR_DICT (iterator)))
-    ->iter_name_next (name, iterator);
+    ->iter_match_next (name, compare, iterator);
 }
 
 int
@@ -614,12 +646,12 @@ iterator_hashed_advance (struct dict_iterator *iterator)
 }
 
 static struct symbol *
-iter_name_first_hashed (const struct dictionary *dict,
-			const char *name,
-			struct dict_iterator *iterator)
+iter_match_first_hashed (const struct dictionary *dict,
+			 const char *name,
+			 int (*compare) (const char *, const char *),
+			 struct dict_iterator *iterator)
 {
-  unsigned int hash_index
-    = msymbol_hash_iw (name) % DICT_HASHED_NBUCKETS (dict);
+  unsigned int hash_index = dict_hash (name) % DICT_HASHED_NBUCKETS (dict);
   struct symbol *sym;
 
   DICT_ITERATOR_DICT (iterator) = dict;
@@ -632,8 +664,8 @@ iter_name_first_hashed (const struct dictionary *dict,
        sym != NULL;
        sym = sym->hash_next)
     {
-      /* Warning: the order of arguments to strcmp_iw matters!  */
-      if (strcmp_iw (SYMBOL_SEARCH_NAME (sym), name) == 0)
+      /* Warning: the order of arguments to compare matters!  */
+      if (compare (SYMBOL_SEARCH_NAME (sym), name) == 0)
 	{
 	  break;
 	}
@@ -645,7 +677,9 @@ iter_name_first_hashed (const struct dictionary *dict,
 }
 
 static struct symbol *
-iter_name_next_hashed (const char *name, struct dict_iterator *iterator)
+iter_match_next_hashed (const char *name,
+			int (*compare) (const char *, const char *),
+			struct dict_iterator *iterator)
 {
   struct symbol *next;
 
@@ -653,7 +687,7 @@ iter_name_next_hashed (const char *name, struct dict_iterator *iterator)
        next != NULL;
        next = next->hash_next)
     {
-      if (strcmp_iw (SYMBOL_SEARCH_NAME (next), name) == 0)
+      if (compare (SYMBOL_SEARCH_NAME (next), name) == 0)
 	break;
     }
 
@@ -671,8 +705,8 @@ insert_symbol_hashed (struct dictionary *dict,
   unsigned int hash_index;
   struct symbol **buckets = DICT_HASHED_BUCKETS (dict);
 
-  hash_index = (msymbol_hash_iw (SYMBOL_SEARCH_NAME (sym))
-		% DICT_HASHED_NBUCKETS (dict));
+  hash_index = 
+    dict_hash (SYMBOL_SEARCH_NAME (sym)) % DICT_HASHED_NBUCKETS (dict);
   sym->hash_next = buckets[hash_index];
   buckets[hash_index] = sym;
 }
@@ -746,6 +780,60 @@ expand_hashtable (struct dictionary *dict)
   xfree (old_buckets);
 }
 
+/* Produce an unsigned hash value from STRING0 that is consistent
+   with strcmp_iw, strcmp, and, at least on Ada symbols, wild_match.
+   That is, two identifiers equivalent according to any of those three
+   comparison operators hash to the same value.  */
+
+static unsigned int
+dict_hash (const char *string)
+{
+  /* The Ada-encoded version of a name P1.P2...Pn has either the form
+     P1__P2__...Pn<suffix> or _ada_P1__P2__...Pn<suffix> (where the Pi
+     are lower-cased identifiers).  The <suffix> (which can be empty)
+     encodes additional information about the denoted entity.  This
+     routine hashes such names to msymbol_hash_iw(Pn).  It actually
+     does this for a superset of both valid Pi and of <suffix>, but 
+     in other cases it simply returns msymbol_hash_iw(STRING0).  */
+
+  unsigned int hash;
+  int c;
+
+  if (*string == '_' && strncmp (string, "_ada_", 5) == 0)
+    string += 5;
+
+  hash = 0;
+  while (*string)
+    {
+      switch (*string)
+	{
+	case '$':
+	case '.':
+	case 'X':
+	case '(':
+	  return hash;
+	case ' ':
+	  string += 1;
+	  break;
+	case '_':
+	  if (string[1] == '_')
+	    {
+	      if (((c = string[2]) < 'a' || c > 'z') && c != 'O')
+		return hash;
+	      hash = 0;
+	      string += 2;
+	      break;
+	    }
+	  /* FALL THROUGH */
+	default:
+	  hash = hash * 67 + *string - 113;
+	  string += 1;
+	  break;
+	}
+    }
+  return hash;
+}
+
 /* Functions for DICT_LINEAR and DICT_LINEAR_EXPANDABLE.  */
 
 static struct symbol *
@@ -769,18 +857,21 @@ iterator_next_linear (struct dict_iterator *iterator)
 }
 
 static struct symbol *
-iter_name_first_linear (const struct dictionary *dict,
-			const char *name,
-			struct dict_iterator *iterator)
+iter_match_first_linear (const struct dictionary *dict,
+			 const char *name,
+			 int (*compare) (const char *, const char *),
+			 struct dict_iterator *iterator)
 {
   DICT_ITERATOR_DICT (iterator) = dict;
   DICT_ITERATOR_INDEX (iterator) = -1;
 
-  return iter_name_next_linear (name, iterator);
+  return iter_match_next_linear (name, compare, iterator);
 }
 
 static struct symbol *
-iter_name_next_linear (const char *name, struct dict_iterator *iterator)
+iter_match_next_linear (const char *name,
+			int (*compare) (const char *, const char *),
+			struct dict_iterator *iterator)
 {
   const struct dictionary *dict = DICT_ITERATOR_DICT (iterator);
   int i, nsyms = DICT_LINEAR_NSYMS (dict);
@@ -789,7 +880,7 @@ iter_name_next_linear (const char *name, struct dict_iterator *iterator)
   for (i = DICT_ITERATOR_INDEX (iterator) + 1; i < nsyms; ++i)
     {
       sym = DICT_LINEAR_SYM (dict, i);
-      if (strcmp_iw (SYMBOL_SEARCH_NAME (sym), name) == 0)
+      if (compare (SYMBOL_SEARCH_NAME (sym), name) == 0)
 	{
 	  retval = sym;
 	  break;