[binutils-gdb] Avoid extra allocations in block

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f52688890edd7c587ec11cf1d565f235e41a6c43

commit f52688890edd7c587ec11cf1d565f235e41a6c43
Author: Tom Tromey <tom@tromey.com>
Date:   Mon Jan 16 17:04:39 2023 -0700

    Avoid extra allocations in block
    
    block_set_scope and block_set_using unconditionally allocate the block
    namespace object.  However, this isn't truly needed, so arrange to
    only allocate when it is.

Diff:
---
 gdb/block.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/gdb/block.c b/gdb/block.c
index 751f67d30f7..f24a2b5d084 100644
--- a/gdb/block.c
+++ b/gdb/block.c
@@ -320,6 +320,12 @@ void
 block_set_scope (struct block *block, const char *scope,
 		 struct obstack *obstack)
 {
+  if (scope == nullptr || scope[0] == '\0')
+    {
+      /* Don't bother.  */
+      return;
+    }
+
   block_initialize_namespace (block, obstack);
 
   block->namespace_info ()->scope = scope;
@@ -346,6 +352,12 @@ block_set_using (struct block *block,
 		 struct using_direct *using_decl,
 		 struct obstack *obstack)
 {
+  if (using_decl == nullptr)
+    {
+      /* Don't bother.  */
+      return;
+    }
+
   block_initialize_namespace (block, obstack);
 
   block->namespace_info ()->using_decl = using_decl;