[review] Only make a nullterminated string if we need to

["Christian Biesinger (Code Review)" <gerrit at gnutoolchain-gerrit dot osci dot io>]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/222
......................................................................

Only make a nullterminated string if we need to

As of 7bb43059820c5febb4509b15202a93efde442bc6, we no longer need
a nullterminated linkage_name to look up the entry in the hash table.

So this patch makes it so we only make the copy if the entry was
not found.

gdb/ChangeLog:

2019-10-22  Christian Biesinger  <cbiesinger@google.com>

	* symtab.c (symbol_set_names): Only make a nullterminated copy of
	linkage_name if the entry was not found and we need to demangle.

Change-Id: I183302e1f51483ff6dff0fd5c3b0f32f0f04a5d2
---
M gdb/symtab.c
1 file changed, 16 insertions(+), 16 deletions(-)



diff --git a/gdb/symtab.c b/gdb/symtab.c
index 0a87fec..787c4b6 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -829,8 +829,6 @@
 		  struct objfile_per_bfd_storage *per_bfd)
 {
   struct demangled_name_entry **slot;
-  /* A 0-terminated copy of the linkage name.  */
-  const char *linkage_name_copy;
 
   if (gsymbol->language == language_ada)
     {
@@ -855,20 +853,7 @@
   if (per_bfd->demangled_names_hash == NULL)
     create_demangled_names_hash (per_bfd);
 
-  if (linkage_name[len] != '\0')
-    {
-      char *alloc_name;
-
-      alloc_name = (char *) alloca (len + 1);
-      memcpy (alloc_name, linkage_name, len);
-      alloc_name[len] = '\0';
-
-      linkage_name_copy = alloc_name;
-    }
-  else
-    linkage_name_copy = linkage_name;
-
-  struct demangled_name_entry entry (gdb::string_view (linkage_name_copy, len));
+  struct demangled_name_entry entry (gdb::string_view (linkage_name, len));
   slot = ((struct demangled_name_entry **)
 	  htab_find_slot (per_bfd->demangled_names_hash.get (),
 			  &entry, INSERT));
@@ -880,6 +865,21 @@
       || (gsymbol->language == language_go
 	  && (*slot)->demangled[0] == '\0'))
     {
+      /* A 0-terminated copy of the linkage name.  */
+      const char *linkage_name_copy;
+      if (linkage_name[len] != '\0')
+	{
+	  char *alloc_name;
+
+	  alloc_name = (char *) alloca (len + 1);
+	  memcpy (alloc_name, linkage_name, len);
+	  alloc_name[len] = '\0';
+
+	  linkage_name_copy = alloc_name;
+	}
+      else
+	linkage_name_copy = linkage_name;
+
       char *demangled_name_ptr
 	= symbol_find_demangled_name (gsymbol, linkage_name_copy);
       gdb::unique_xmalloc_ptr<char> demangled_name (demangled_name_ptr);