src: simplify loop arithmetic in GetCPUInfo

Cache the repeated operations and reuse; potentially generating
efficient code in some platforms, and improving readability.

PR-URL: #26183
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/os.js

@@ -92,16 +92,17 @@ function cpus() {
   // [] is a bugfix for a regression introduced in 51cea61
   const data = getCPUs() || [];
   const result = [];
-  for (var i = 0; i < data.length; i += 7) {
+  let i = 0;
+  while (i < data.length) {
     result.push({
-      model: data[i],
-      speed: data[i + 1],
+      model: data[i++],
+      speed: data[i++],
       times: {
-        user: data[i + 2],
-        nice: data[i + 3],
-        sys: data[i + 4],
-        idle: data[i + 5],
-        irq: data[i + 6]
+        user: data[i++],
+        nice: data[i++],
+        sys: data[i++],
+        idle: data[i++],
+        irq: data[i++]
       }
     });
   }

src/node_os.cc

@@ -126,15 +126,15 @@ static void GetCPUInfo(const FunctionCallbackInfo<Value>& args) {
   // The array is in the format
   // [model, speed, (5 entries of cpu_times), model2, speed2, ...]
   std::vector<Local<Value>> result(count * 7);
-  for (int i = 0; i < count; i++) {
+  for (int i = 0, j = 0; i < count; i++) {
     uv_cpu_info_t* ci = cpu_infos + i;
-    result[i * 7] = OneByteString(isolate, ci->model);
-    result[i * 7 + 1] = Number::New(isolate, ci->speed);
-    result[i * 7 + 2] = Number::New(isolate, ci->cpu_times.user);
-    result[i * 7 + 3] = Number::New(isolate, ci->cpu_times.nice);
-    result[i * 7 + 4] = Number::New(isolate, ci->cpu_times.sys);
-    result[i * 7 + 5] = Number::New(isolate, ci->cpu_times.idle);
-    result[i * 7 + 6] = Number::New(isolate, ci->cpu_times.irq);
+    result[j++] = OneByteString(isolate, ci->model);
+    result[j++] = Number::New(isolate, ci->speed);
+    result[j++] = Number::New(isolate, ci->cpu_times.user);
+    result[j++] = Number::New(isolate, ci->cpu_times.nice);
+    result[j++] = Number::New(isolate, ci->cpu_times.sys);
+    result[j++] = Number::New(isolate, ci->cpu_times.idle);
+    result[j++] = Number::New(isolate, ci->cpu_times.irq);
   }
 
   uv_free_cpu_info(cpu_infos, count);