stdlib: Add util methods for time measurements

runtime/src/main/cpp/Time.cpp

@@ -0,0 +1,21 @@
+#include <chrono>
+#include "Types.h"
+#include "Natives.h"
+
+using namespace std::chrono;
+
+extern "C" {
+
+KLong Kotlin_system_getTimeMillis() {
+  return duration_cast<milliseconds>(high_resolution_clock::now().time_since_epoch()).count();
+}
+
+KLong Kotlin_system_getTimeNanos() {
+  return duration_cast<nanoseconds>(high_resolution_clock::now().time_since_epoch()).count();
+}
+
+KLong Kotlin_system_getTimeMicros() {
+  return duration_cast<microseconds>(high_resolution_clock::now().time_since_epoch()).count();
+}
+
+}  // extern "C"

runtime/src/main/kotlin/kotlin/system/Timing.kt

@@ -0,0 +1,34 @@
+package kotlin.system
+
+@PublishedApi
+@SymbolName("Kotlin_system_getTimeMillis")
+internal external fun getTimeMillis() : Long
+
+@PublishedApi
+@SymbolName("Kotlin_system_getTimeNanos")
+internal external fun getTimeNanos() : Long
+
+@PublishedApi
+@SymbolName("Kotlin_system_getTimeMicros")
+internal external fun getTimeMicros() : Long
+
+/** Executes the given block and returns elapsed time in milliseconds. */
+public inline fun measureTimeMillis(block: () -> Unit) : Long {
+    val start = getTimeMillis()
+    block()
+    return getTimeMillis() - start
+}
+
+/** Executes the given block and returns elapsed time in microseconds (Kotlin/Native only). */
+public inline fun measureTimeMicros(block: () -> Unit) : Long {
+    val start = getTimeMicros()
+    block()
+    return getTimeMicros() - start
+}
+
+/** Executes the given block and returns elapsed time in nanoseconds. */
+public inline fun measureNanoTime(block: () -> Unit) : Long {
+    val start = getTimeNanos()
+    block()
+    return getTimeNanos() - start
+}