Added option to manually specify a reference to compare the results to.

src/options.rs

@@ -204,6 +204,9 @@ pub struct Options {
     /// Whether or not to ignore non-zero exit codes
     pub command_failure_action: CmdFailureAction,
 
+    // Command to use as a reference for relative speed comparison
+    pub reference_command: Option<String>,
+
     /// Command(s) to run before each timing run
     pub preparation_command: Option<Vec<String>>,
 
@@ -245,6 +248,7 @@ impl Default for Options {
             warmup_count: 0,
             min_benchmarking_time: 3.0,
             command_failure_action: CmdFailureAction::RaiseError,
+            reference_command: None,
             preparation_command: None,
             conclusion_command: None,
             setup_command: None,
@@ -304,6 +308,8 @@ impl Options {
 
         options.setup_command = matches.get_one::<String>("setup").map(String::from);
 
+        options.reference_command = matches.get_one::<String>("reference").map(String::from);
+
         options.preparation_command = matches
             .get_many::<String>("prepare")
             .map(|values| values.map(String::from).collect::<Vec<String>>());