Skip calling f.read for `overwrite: true`-only cases

We only need to set outpath for that case.

1 files changed, 4 insertions, 2 deletions

diff --git a/tool/lib/output.rb b/tool/lib/output.rb
index a7faa44810..51e3d32010 100644
--- a/tool/lib/output.rb
+++ b/tool/lib/output.rb
@@ -30,8 +30,10 @@ class Output
 
     if (@ifchange or overwrite or create_only) and (@vpath.open(@path, "rb") {|f|
       outpath = f.path
-      original = f.read
-      (@ifchange and original == data) or (create_only and !original.empty?)
+      if @ifchange or create_only
+        original = f.read
+        (@ifchange and original == data) or (create_only and !original.empty?)
+      end
     } rescue false)
       puts "#{outpath} #{unchanged}"
       written = false