commands/spec: add outputRoot(--output_root) option

src/commands/spec.ts

@@ -57,6 +57,14 @@ export interface RunCPUOptions {
      * Meaning: Attempt to create all processes in a single group. Improves the chances that ^C will get the whole run, not just one of the children.
      */
     setprocgroup?: boolean;
+
+    /**
+     * If set to a non-empty value, all output files will be rooted under the named directory, instead of under $SPEC (or %SPEC%).
+     * If directory is not an absolute path (one that begins with "/" on Unix, or a device name on Windows), the path will be created under $SPEC.
+     *
+     * This option can be useful for sharing an installation.
+     */
+    outputRoot?: string;
 }
 
 export function runcpuOptions(o: RunCPUOptions): string[] {
@@ -76,5 +84,6 @@ export function runcpuOptions(o: RunCPUOptions): string[] {
         ...undefList(o.benchmarks, bench => bench),
         ...undefList(o.outputFormat, of => ["--output_format", of.join(",")]),
         ...optSwitch("--setprocgroup", o.setprocgroup),
+        ...optFlag("--output_root", o.outputRoot),
     ];
 }