Add a tool to locate global variables

build_tools/find_globals.fish

@@ -0,0 +1,19 @@
+#!/usr/bin/env fish
+
+# Finds global variables by parsing the output of 'nm'
+# for object files in this directory.
+# This was written for macOS nm.
+
+set total_globals 0
+
+for file in ./**.o
+  set filename (basename $file)
+  for line in (nm -p -P -U $file)
+    # Look in data (dD) and bss (bB) segments.
+    set matches (string match --regex '^([^ ]+) ([dDbB])' -- $line) ; or continue
+    echo $filename (echo $matches[2] | c++filt) $matches[3]
+    set total_globals (math $total_globals + 1)
+  end
+end
+
+echo "Total: $total_globals"