[patch] Speed up read_psymtabs_with_fullname

[Doug Evans]

Hi.
I happened to do "list 1" in a trivial program and it was taking forever.
I traced this to read_psymtabs_with_fullname trying to open every source file.
I have libc debug info installed which exacerbated the problem.

I will apply this fix (which is what we do elsewhere for this issue)
in a few days if there are no objections.

2013-04-02  Doug Evans  <dje@google.com>

	* psymtab.c (read_psymtabs_with_fullname): Don't call
	psymtab_to_fullname if the basenames are different.

Index: psymtab.c
===================================================================
RCS file: /cvs/src/src/gdb/psymtab.c,v
retrieving revision 1.70
diff -u -p -r1.70 psymtab.c
--- psymtab.c	20 Mar 2013 18:28:48 -0000	1.70
+++ psymtab.c	2 Apr 2013 22:58:36 -0000
@@ -1114,7 +1114,11 @@ read_psymtabs_with_fullname (struct objf
       if (p->anonymous)
 	continue;
 
-      if (filename_cmp (fullname, psymtab_to_fullname (p)) == 0)
+      /* psymtab_to_fullname tries to open the file which is unnecessarily
+	 slow.  Don't call it if we know the basenames don't match.  */
+      if ((basenames_may_differ
+	   || filename_cmp (lbasename (fullname), lbasename (p->filename)) == 0)
+	  && filename_cmp (fullname, psymtab_to_fullname (p)) == 0)
 	psymtab_to_symtab (objfile, p);
     }
 }