Change nbench warmup to run full, normal iterations (#2829)

* Change warmup to run full, normal iterations

* style

src/tools/nbench/benchmark.cpp

@@ -178,18 +178,13 @@ vector<runtime::PerformanceCounter> run_benchmark(shared_ptr<Function> f,
         }
     }
 
-    if (warmup_iterations)
+    stopwatch t1;
+    for (size_t i = 0; i < iterations + warmup_iterations; i++)
     {
-        for (int i = 0; i < warmup_iterations; i++)
+        if (i == warmup_iterations)
         {
-            compiled_func->call(results, args);
+            t1.start();
         }
-    }
-
-    stopwatch t1;
-    t1.start();
-    for (size_t i = 0; i < iterations; i++)
-    {
         if (copy_data)
         {
             for (size_t arg_index = 0; arg_index < args.size(); arg_index++)