From: Tom Tromey <tom@tromey.com>
Date: Fri, 2 Feb 2024 01:56:43 +0000 (-0700)
Subject: Avoid an allocation in attr_to_dynamic_prop
X-Git-Tag: gdb-15-branchpoint~1055
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4b858d4dbbdc2d497231d6340a49414c88db7dbb;p=thirdparty%2Fbinutils-gdb.git

Avoid an allocation in attr_to_dynamic_prop

I noticed that attr_to_dynamic_prop allocates a dwarf_block, when no
allocation is required.  This patch stack-allocates the object
instead.

Reviewed-By: Tom de Vries <tdevries@suse.de>
---

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index eab56ec505d..a5a22c068eb 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -15371,24 +15371,23 @@ attr_to_dynamic_prop (const struct attribute *attr, struct die_info *die,
       baton->locexpr.per_cu = cu->per_cu;
       baton->locexpr.per_objfile = per_objfile;
 
-      struct dwarf_block *block;
+      struct dwarf_block block;
       if (attr->form == DW_FORM_data16)
 	{
 	  size_t data_size = 16;
-	  block = XOBNEW (obstack, struct dwarf_block);
-	  block->size = (data_size
-			 + 2 /* Extra bytes for DW_OP and arg.  */);
-	  gdb_byte *data = XOBNEWVEC (obstack, gdb_byte, block->size);
+	  block.size = (data_size
+			+ 2 /* Extra bytes for DW_OP and arg.  */);
+	  gdb_byte *data = XOBNEWVEC (obstack, gdb_byte, block.size);
 	  data[0] = DW_OP_implicit_value;
 	  data[1] = data_size;
 	  memcpy (&data[2], attr->as_block ()->data, data_size);
-	  block->data = data;
+	  block.data = data;
 	}
       else
-	block = attr->as_block ();
+	block = *attr->as_block ();
 
-      baton->locexpr.size = block->size;
-      baton->locexpr.data = block->data;
+      baton->locexpr.size = block.size;
+      baton->locexpr.data = block.data;
       switch (attr->name)
 	{
 	case DW_AT_string_length: