benchmark,lib: add process.hrtime.bigint benchmark

Add a benchmark, and amend the relevant source code comment to state
that currently, switching to directly returning a BigInt is not
stopped by technical obstacles but rather the fact that using a typed
array is actually a bit faster (about 2.5 %, measured locally).
PR-URL: #26381
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: addaleax

benchmark/process/bench-hrtime.js

@@ -5,27 +5,38 @@ const assert = require('assert');
 
 constbench=common.createBenchmark(main,{
 n: [1e6],
-type: ['raw','diff']
+type: ['raw','diff','bigint']
 });
 
 functionmain({ n, type }){
 consthrtime=process.hrtime;
-varnoDead=hrtime();
+varnoDead=type==='bigint' ? hrtime.bigint() : hrtime();
 vari;
 
-if(type==='raw'){
-bench.start();
-for(i=0;i<n;i++){
-noDead=hrtime();
-}
-bench.end(n);
-}else{
-bench.start();
-for(i=0;i<n;i++){
-noDead=hrtime(noDead);
-}
-bench.end(n);
+switch(type){
+case'raw':
+bench.start();
+for(i=0;i<n;i++){
+noDead=hrtime();
+}
+bench.end(n);
+break;
+case'diff':
+bench.start();
+for(i=0;i<n;i++){
+noDead=hrtime(noDead);
+}
+bench.end(n);
+break;
+case'bigint':
+bench.start();
+for(i=0;i<n;i++){
+noDead=hrtime.bigint();
+}
+bench.end(n);
+break;
 }
 
-assert.ok(Array.isArray(noDead));
+// eslint-disable-next-line valid-typeof
+assert.ok(Array.isArray(noDead)||typeofnoDead==='bigint');
 }

lib/internal/process/per_thread.js

@@ -122,8 +122,8 @@ function wrapProcessMethods(binding) {
 ];
 }
 
-// Use a BigUint64Array in the closure because V8 does not have an API for
-// creating a BigInt out of a uint64_t yet.
+// Use a BigUint64Array in the closure because this is actually a bit
+// faster than simply returning a BigInt from C++ in V8 7.1.
 consthrBigintValues=newBigUint64Array(1);
 functionhrtimeBigInt(){
 _hrtimeBigInt(hrBigintValues);