Merge pull request #4358 from pleroy/CPUId

Add support for querying the CPU flags from C#

Author: pleroy

ksp_plugin/interface.cpp

@@ -667,6 +667,14 @@ int __cdecl principia__GetStderrLogging() {
   return m.Return(FLAGS_stderrthreshold);
 }
 
+void __cdecl principia__GetCPUIDFeatureFlags(bool* const has_avx,
+                                             bool* const has_fma) {
+  journal::Method<journal::GetCPUIDFeatureFlags> m({has_avx, has_fma});
+  *has_avx = CPUIDFeatureFlag::AVX.IsSet();
+  *has_fma = CPUIDFeatureFlag::FMA.IsSet();
+  return m.Return();
+}
+
 int __cdecl principia__GetSuppressedLogging() {
   journal::Method<journal::GetSuppressedLogging> m;
   return m.Return(FLAGS_minloglevel);

ksp_plugin_adapter/loader.cs

@@ -96,7 +96,18 @@ internal static string LoadPrincipiaDllAndInitGoogleLogging() {
       Interface.LoadSymbols();
       loaded_principia_dll = true;
       Log.InitGoogleLogging();
-      return null;
+      Interface.GetCPUIDFeatureFlags(out bool has_avx, out bool has_fma);
+      Log.Info("Processor " +
+               (has_avx ? "has" : "does not have") +
+               " AVX support and " +
+               (has_fma ? "has" : "does not have") +
+               " FMA support.");
+      if (has_fma && !has_avx) {
+        return "Principia does not run on processors with FMA support but no " +
+               "AVX support.";
+      } else {
+        return null;
+      }
     } catch (Exception e) {
       UnityEngine.Debug.LogException(e);
       if (non_ascii_path_error != null) {

serialization/journal.proto

@@ -1327,6 +1327,17 @@ message GetBufferedLogging {
   optional Return return = 3;
 }
 
+message GetCPUIDFeatureFlags {
+  extend Method {
+    optional GetCPUIDFeatureFlags extension = 5198;
+  }
+  message Out {
+    required bool has_avx = 1;
+    required bool has_fma = 2;
+  }
+  optional Out out = 2;
+}
+
 message GetStderrLogging {
   extend Method {
     optional GetStderrLogging extension = 5007;