[rfa] tweak sorting of partial symbols

[David Carlton <carlton at math dot stanford dot edu>]

Right now, partial symbols are sorted via strcmp.  But if you look up
NAME in the partial symbols, then what lookup_partial_symbol does is:

* Figure out where NAME fits under the strcmp ordering.

* Then, starting from that place in the partial symbols, look at all
  the partial symbols until we either find the right one or until we
  find one such that strcmp_iw(SYM_NAME,NAME) doesn't match.

In particular, there's the assumption that all symbols for which
strcmp_iw(SYM_NAME,NAME) matches are sorted via strcmp into a group
that starts out at the position where strcmp would put NAME.

But I can't see why this should be true.  So this patch adds a new
function strcmp_iw_ordered (not the best name, perhaps) that is
suitable for use via qsort (unlike strcmp_iw, which doesn't provide an
ordering or even an equivalence relation) and which does have the
desired property.  It does this by ignoring whitespace and by treating
'(' as the smallest non-NULL character (because, in some
circumstances, strcmp_iw wants to ignore matches where the difference
starts with an open parenthesis).

In practice, this should rarely if ever pose a problem, but it's a
good idea for the sake of pedanticism.  After this one goes in, I'll
also commit that patch to make_symbol_overload_list that we talked
about earlier today.

Tested on i686-pc-linux-gnu/GCC3.1/DWARF-2; OK to apply?

David Carlton
carlton at math dot stanford dot edu

2003-02-21  David Carlton  <carlton at math dot stanford dot edu>

	* symtab.c (lookup_partial_symbol): Use strcmp_iw_ordered to
	do the comparison, not strcmp.
	* symfile.c (compare_psymbols): Ditto.
	* defs.h: Declare strcmp_iw_ordered.
	* utils.c (strcmp_iw_ordered): New function.

Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.90
diff -u -p -r1.90 symtab.c
--- symtab.c	20 Feb 2003 22:07:38 -0000	1.90
+++ symtab.c	22 Feb 2003 01:05:45 -0000
@@ -1379,9 +1379,10 @@ lookup_partial_symbol (struct partial_sy
       do_linear_search = 0;
 
       /* Binary search.  This search is guaranteed to end with center
-         pointing at the earliest partial symbol with the correct
-         name.  At that point *all* partial symbols with that name
-         will be checked against the correct namespace. */
+         pointing at the earliest partial symbol whose name might be
+         correct.  At that point *all* partial symbols with an
+         appropriate name will be checked against the correct
+         namespace.  */
 
       bottom = start;
       top = start + length - 1;
@@ -1396,7 +1397,7 @@ lookup_partial_symbol (struct partial_sy
 	    {
 	      do_linear_search = 1;
 	    }
-	  if (strcmp (SYMBOL_PRINT_NAME (*center), name) >= 0)
+	  if (strcmp_iw_ordered (SYMBOL_PRINT_NAME (*center), name) >= 0)
 	    {
 	      top = center;
 	    }
Index: symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.89
diff -u -p -r1.89 symfile.c
--- symfile.c	20 Feb 2003 17:17:25 -0000	1.89
+++ symfile.c	22 Feb 2003 01:05:40 -0000
@@ -213,52 +213,17 @@ compare_symbols (const void *s1p, const 
   return (strcmp (SYMBOL_PRINT_NAME (*s1), SYMBOL_PRINT_NAME (*s2)));
 }
 
-/*
-
-   LOCAL FUNCTION
-
-   compare_psymbols -- compare two partial symbols by name
-
-   DESCRIPTION
-
-   Given pointers to pointers to two partial symbol table entries,
-   compare them by name and return -N, 0, or +N (ala strcmp).
-   Typically used by sorting routines like qsort().
-
-   NOTES
-
-   Does direct compare of first two characters before punting
-   and passing to strcmp for longer compares.  Note that the
-   original version had a bug whereby two null strings or two
-   identically named one character strings would return the
-   comparison of memory following the null byte.
-
- */
+/* This compares two partial symbols by names, using strcmp_iw_ordered
+   for the comparison.  */
 
 static int
 compare_psymbols (const void *s1p, const void *s2p)
 {
-  register struct partial_symbol **s1, **s2;
-  register char *st1, *st2;
-
-  s1 = (struct partial_symbol **) s1p;
-  s2 = (struct partial_symbol **) s2p;
-  st1 = SYMBOL_PRINT_NAME (*s1);
-  st2 = SYMBOL_PRINT_NAME (*s2);
-
+  struct partial_symbol *const *s1 = s1p;
+  struct partial_symbol *const *s2 = s2p;
 
-  if ((st1[0] - st2[0]) || !st1[0])
-    {
-      return (st1[0] - st2[0]);
-    }
-  else if ((st1[1] - st2[1]) || !st1[1])
-    {
-      return (st1[1] - st2[1]);
-    }
-  else
-    {
-      return (strcmp (st1, st2));
-    }
+  return strcmp_iw_ordered (SYMBOL_PRINT_NAME (*s1),
+			    SYMBOL_PRINT_NAME (*s2));
 }
 
 void
Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.113
diff -u -p -r1.113 defs.h
--- defs.h	14 Feb 2003 13:58:05 -0000	1.113
+++ defs.h	22 Feb 2003 01:05:31 -0000
@@ -305,6 +305,8 @@ extern void notice_quit (void);
 
 extern int strcmp_iw (const char *, const char *);
 
+extern int strcmp_iw_ordered (const char *, const char *);
+
 extern int streq (const char *, const char *);
 
 extern int subset_compare (char *, char *);
Index: utils.c
===================================================================
RCS file: /cvs/src/src/gdb/utils.c,v
retrieving revision 1.96
diff -u -p -r1.96 utils.c
--- utils.c	7 Feb 2003 00:27:30 -0000	1.96
+++ utils.c	22 Feb 2003 01:05:36 -0000
@@ -2358,6 +2358,64 @@ strcmp_iw (const char *string1, const ch
   return (*string1 != '\0' && *string1 != '(') || (*string2 != '\0');
 }
 
+/* This is like strcmp except that it ignores whitespace and treats
+   '(' as the first non-NULL character in terms of ordering.  Like
+   strcmp (and unlike strcmp_iw), it returns negative if STRING1 <
+   STRING2, 0 if STRING2 = STRING2, and positive if STRING1 > STRING2
+   according to that ordering.
+
+   If a list is sorted according to this function and if you want to
+   find names in the list that match some fixed NAME according to
+   strcmp_iw(LIST_ELT, NAME), then the place to start looking is right
+   where this function would put NAME.  */
+
+int
+strcmp_iw_ordered (const char *string1, const char *string2)
+{
+  while ((*string1 != '\0') && (*string2 != '\0'))
+    {
+      while (isspace (*string1))
+	{
+	  string1++;
+	}
+      while (isspace (*string2))
+	{
+	  string2++;
+	}
+      if (*string1 != *string2)
+	{
+	  break;
+	}
+      if (*string1 != '\0')
+	{
+	  string1++;
+	  string2++;
+	}
+    }
+
+  switch (*string1)
+    {
+      /* Characters are non-equal unless they're both '\0'; we want to
+	 make sure we get the comparison right according to our
+	 comparison in the cases where one of them is '\0' or '('.  */
+    case '\0':
+      if (*string2 == '\0')
+	return 0;
+      else
+	return -1;
+    case '(':
+      if (*string2 == '\0')
+	return 1;
+      else
+	return -1;
+    default:
+      if (*string2 == '(')
+	return 1;
+      else
+	return *string1 - *string2;
+    }
+}
+
 /* A simple comparison function with opposite semantics to strcmp.  */
 
 int