[COMMITTED PATCH] Fix PR symtab/17591

[Doug Evans <dje@google.com>]

Hi.

This patch fixes pr 17591.
Regression tested on amd64-linux.

The removing of the parens wasn't taking into account
looking up "(anonymous namespace)".

It turns out there can be a significant performance cost.
The lookup would use "" which in the program where this
was found had an entry in .gdb_index with ~1000 CUs,
none of which had (anonymous namespace),
so we were needlessly reading in a *lot* of debug info.

Before:

(gdb) pt obj
type = ...
Command execution time: 50.712058 (cpu), 52.275078 (wall)
Space used: 2379862016 (+2180878336 for this command)
#symtabs: 150433 (+150064), #primary symtabs: 2090 (+2081), #blocks: 774710 (+773450)

After:

(gdb) pt obj
type = ...
Command execution time: 0.850209 (cpu), 0.864219 (wall)
Space used: 232112128 (+33136640 for this command)
#symtabs: 3040 (+2671), #primary symtabs: 107 (+98), #blocks: 22595 (+21335)

2014-11-13  Doug Evans  <dje@google.com>

	PR symtab/17591
	* dwarf2read.c (find_slot_in_mapped_hash): Handle
	"(anonymous namespace)".

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index ce37adf..0c97447 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2917,7 +2917,11 @@ find_slot_in_mapped_hash (struct mapped_index *index, const char *name,
     {
       /* NAME is already canonical.  Drop any qualifiers as .gdb_index does
 	 not contain any.  */
-      const char *paren = strchr (name, '(');
+      const char *paren = NULL;
+
+      /* Need to handle "(anonymous namespace)".  */
+      if (*name != '(')
+	paren = strchr (name, '(');
 
       if (paren)
 	{