Replace some problematic platform specific codepaths with intrinsics in runtime. (case 1022228)

Author: joncham

mcs/class/System/System.Net.NetworkInformation/IPGlobalProperties.cs

@@ -163,6 +163,17 @@ public override string DomainName {
 	}
 #endif
 
+#if UNITY
+	sealed class UnixNoLibCIPGlobalProperties : UnixIPGlobalProperties
+	{
+		public override string DomainName {
+			get {
+				return String.Empty;
+			}
+		}
+	}
+#endif
+
 	// It expects /proc/net/snmp (or /usr/compat/linux/proc/net/snmp),
 	// formatted like:
 	// http://www.linuxdevcenter.com/linux/2000/11/16/example5.html

mcs/class/System/System/Platform.cs

@@ -79,14 +79,15 @@ private static void CheckOS() {
 		}
 #endif
 
+		// UNITY: runtime replaces this with intrinsic
 		public static bool IsMacOS {
 			get {
 				if (!checkedOS)
 #if UNITY
 					try {
 						CheckOS();
 					}
-					catch (DllNotFoundException e) {
+					catch (DllNotFoundException) {
 						// libc does not exist, so this is not MacOS
 						isMacOS = false;
 					}
@@ -97,6 +98,7 @@ public static bool IsMacOS {
 			}
 		}
 
+		// UNITY: runtime replaces this with intrinsic
 		public static bool IsFreeBSD {
 			get {
 				if (!checkedOS)

mcs/class/referencesource/System/net/System/Net/NetworkInformation/IPGlobalProperties.cs

@@ -12,6 +12,11 @@ namespace System.Net.NetworkInformation
 
     public abstract class IPGlobalProperties
     {
+#if UNITY
+        // defaults to false, but may be replaced by intrinsic in runtime
+        static bool PlatformNeedsLibCWorkaround { get; }
+#endif
+
         public static IPGlobalProperties GetIPGlobalProperties()
         {
 #if MONODROID
@@ -21,6 +26,10 @@ public static IPGlobalProperties GetIPGlobalProperties()
 #elif MONO
             switch (Environment.OSVersion.Platform) {
             case PlatformID.Unix:
+#if UNITY
+                if (PlatformNeedsLibCWorkaround)
+                    return new UnixNoLibCIPGlobalProperties();
+#endif
                 MibIPGlobalProperties impl = null;
                 if (Directory.Exists (MibIPGlobalProperties.ProcDir)) {
                     impl = new MibIPGlobalProperties (MibIPGlobalProperties.ProcDir);

mono/mini/method-to-ir.c

@@ -5780,6 +5780,34 @@ mini_emit_inst_for_method (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 			if (mono_type_is_native_blittable (arg0))
 				return mini_emit_memory_load (cfg, arg0, args [0], 0, 0);
 		}
+	} else if (!strcmp (cmethod->klass->image->assembly->aname.name, "System") &&
+			   !strcmp (cmethod->klass->name_space, "System") &&
+			   !strcmp (cmethod->klass->name, "Platform") &&
+			   !strcmp (cmethod->name, "get_IsMacOS")) {
+#if defined(TARGET_OSX)
+		EMIT_NEW_ICONST (cfg, ins, 1);
+#else
+		EMIT_NEW_ICONST (cfg, ins, 0);
+#endif
+		return ins;
+	} else if (!strcmp (cmethod->klass->image->assembly->aname.name, "System") &&
+			   !strcmp (cmethod->klass->name_space, "System") &&
+			   !strcmp (cmethod->klass->name, "Platform") &&
+			   !strcmp (cmethod->name, "get_IsFreeBSD")) {
+#if defined(__FreeBSD__)
+		EMIT_NEW_ICONST (cfg, ins, 1);
+#else
+		EMIT_NEW_ICONST (cfg, ins, 0);
+#endif
+		return ins;
+	} else if (!strcmp (cmethod->klass->image->assembly->aname.name, "System") &&
+			   !strcmp (cmethod->klass->name_space, "System.Net.NetworkInformation") &&
+			   !strcmp (cmethod->klass->name, "IPGlobalProperties") &&
+			   !strcmp (cmethod->name, "get_PlatformNeedsLibCWorkaround")) {
+#if defined(HOST_ANDROID)
+		EMIT_NEW_ICONST (cfg, ins, 1);
+		return ins;
+#endif
 	}
 
 #ifdef MONO_ARCH_SIMD_INTRINSICS