Increased Tuner Safety (CNugteren#616)

* Added safety to ensure the user does not supply too little threads from the --threads parameter.

* Adjusted default arg type based on the change in utilities/utilities.hpp

* Fixed compilation errors

Author: EJainDev

src/tuning/tuning.cpp

@@ -220,7 +220,7 @@ void Tuner(int argc, char* argv[], const int V, GetTunerDefaultsFunc GetTunerDef
   args.device_id =
       GetArgument(command_line_args, help, kArgDevice, ConvertArgument(std::getenv("CLBLAST_DEVICE"), size_t{0}));
   args.precision = GetArgument(command_line_args, help, kArgPrecision, Precision::kSingle);
-  args.extra_threads = GetArgument(command_line_args, help, kArgNumThreads, size_t{1}) - 1;
+  args.extra_threads = GetArgument(command_line_args, help, kArgNumThreads, 1) - 1;
   for (auto& o : defaults.options) {
     if (o == kArgM) {
       args.m = GetArgument(command_line_args, help, kArgM, defaults.default_m);
@@ -272,6 +272,12 @@ void Tuner(int argc, char* argv[], const int V, GetTunerDefaultsFunc GetTunerDef
   const TunerSettings settings = GetTunerSettings(V, args);
 
   // Tests validity of the given arguments
+  if (args.extra_threads < 0) {
+    printf("Tuners cannot run without threads or negative threads. Provided %lli threads. Exiting...\n",
+           args.extra_threads);
+    return;
+  }
+
   TestValidArguments(V, args);
 
   // Initializes OpenCL
@@ -401,7 +407,7 @@ void Tuner(int argc, char* argv[], const int V, GetTunerDefaultsFunc GetTunerDef
   std::vector<ThreadInfo> thread_infos(configurations.size());
   std::vector<std::thread> threads;
   threads.reserve(args.extra_threads);
-  for (size_t i = 0; i < std::min(size_t{args.extra_threads}, configurations.size()); ++i) {
+  for (size_t i = 0; i < std::min(static_cast<size_t>(args.extra_threads), configurations.size()); ++i) {
     threads.push_back(std::thread(&kernelCompilationThread<T>, std::ref(thread_infos), std::cref(configurations), i,
                                   std::cref(settings), std::cref(args), std::cref(device), std::cref(context),
                                   args.extra_threads));

src/utilities/utilities.hpp

@@ -266,7 +266,7 @@ struct Arguments {
   // Common arguments
   size_t platform_id = 0;
   size_t device_id = 0;
-  size_t extra_threads = 1;
+  long long extra_threads = 1;
   Precision precision = Precision::kSingle;
   bool print_help = false;
   bool silent = false;