Make a single managed startup method for CoreCLR

A common configuration for coreclr is event source enabled, startup
hooks disabled, so at least one managed call is inevitable.  Since we
have to call into managed no matter what, let the trimmer determine
what happens once we get there.

This is different from mono where published trimmed apps may have both
startup hooks and event source disabled.  In that case we would rather
avoid a managed call to an empty method early in startup.

src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -229,6 +229,7 @@
     <Compile Include="$(BclSourcesRoot)\System\RuntimeType.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Security\DynamicSecurityMethodAttribute.cs" />
     <Compile Include="$(BclSourcesRoot)\System\String.CoreCLR.cs" />
+    <Compile Include="$(BclSourcesRoot)\System\StartupHookProvider.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\StubHelpers.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Text\StringBuilder.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Threading\Interlocked.CoreCLR.cs" />

src/coreclr/System.Private.CoreLib/src/System/StartupHookProvider.CoreCLR.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+using System;
+using System.Diagnostics;
+using System.Diagnostics.Tracing;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Reflection;
+using System.Runtime.Loader;
+
+namespace System
+{
+    internal partial static class StartupHookProvider
+    {
+        private static void ManagedStartup()
+        {
+#if FEATURE_PERFTRACING
+            if (EventSource.IsSupported)
+                RuntimeEventSource.Initialize();
+#endif
+
+            if (IsSupported)
+                ProcessStartupHooks();
+        }
+    }
+}

src/coreclr/vm/assembly.cpp

@@ -1421,29 +1421,7 @@ static void RunMainPost()
     }
 }
 
-static void RuntimeEventSourceInitialize()
-{
-#ifdef FEATURE_PERFTRACING
-    CONTRACTL
-    {
-        THROWS;
-        GC_TRIGGERS;
-        MODE_COOPERATIVE;
-        INJECT_FAULT(COMPlusThrowOM(););
-    }
-    CONTRACTL_END;
-
-    MethodDescCallSite eventSourceIsSupported(METHOD__EVENT_SOURCE__GET_IS_SUPPORTED);
-
-    if (eventSourceIsSupported.Call_RetBool(NULL))
-    {
-        MethodDescCallSite runtimeEventSourceInitialize(METHOD__RUNTIME_EVENT_SOURCE__INITIALIZE);
-        runtimeEventSourceInitialize.Call(NULL);
-    }
-#endif
-}
-
-static void RunStartupHooks()
+static void RunManagedStartup()
 {
     CONTRACTL
     {
@@ -1454,14 +1432,8 @@ static void RunStartupHooks()
     }
     CONTRACTL_END;
 
-    MethodDescCallSite processStartupHooks(METHOD__STARTUP_HOOK_PROVIDER__PROCESS_STARTUP_HOOKS);
-    processStartupHooks.Call(NULL);
-}
-
-static void RunManagedStartup()
-{
-    RuntimeEventSourceInitialize();
-    RunStartupHooks();
+    MethodDescCallSite managedStartup(METHOD__STARTUP_HOOK_PROVIDER__MANAGED_STARTUP);
+    managedStartup.Call(NULL);
 }
 
 INT32 Assembly::ExecuteMainMethod(PTRARRAYREF *stringArgs, BOOL waitForOtherThreads)

src/coreclr/vm/corelib.h

@@ -332,11 +332,6 @@ DEFINE_FIELD_U(_xptrs,             ExceptionObject,    _xptrs)
 DEFINE_FIELD_U(_xcode,             ExceptionObject,    _xcode)
 DEFINE_FIELD_U(_HResult,           ExceptionObject,    _HResult)
 
-BEGIN_ILLINK_FEATURE_SWITCH(System.Diagnostics.Tracing.EventSource.IsSupported, true, true)
-DEFINE_CLASS(EVENT_SOURCE,         DiagnosticsTracing,      EventSource)
-DEFINE_STATIC_PROPERTY(EVENT_SOURCE, IS_SUPPORTED, IsSupported, Bool)
-END_ILLINK_FEATURE_SWITCH()
-
 
 DEFINE_CLASS(EXCEPTION,             System,                 Exception)
 DEFINE_METHOD(EXCEPTION,            INTERNAL_PRESERVE_STACK_TRACE, InternalPreserveStackTrace, IM_RetVoid)
@@ -696,11 +691,6 @@ DEFINE_METHOD(RUNTIME_HELPERS,      ALLOC_TAILCALL_ARG_BUFFER, AllocTailCallArgB
 DEFINE_METHOD(RUNTIME_HELPERS,      GET_TAILCALL_INFO,      GetTailCallInfo, NoSig)
 DEFINE_METHOD(RUNTIME_HELPERS,      DISPATCH_TAILCALLS,     DispatchTailCalls,          NoSig)
 
-BEGIN_ILLINK_FEATURE_SWITCH(System.Diagnostics.Tracing.EventSource.IsSupported, true, true)
-DEFINE_CLASS(RUNTIME_EVENT_SOURCE,  DiagnosticsTracing,     RuntimeEventSource)
-DEFINE_METHOD(RUNTIME_EVENT_SOURCE, INITIALIZE,             Initialize, SM_RetVoid)
-END_ILLINK_FEATURE_SWITCH()
-
 DEFINE_CLASS(UNSAFE,                CompilerServices,       Unsafe)
 DEFINE_METHOD(UNSAFE,               AS_POINTER,             AsPointer, NoSig)
 DEFINE_METHOD(UNSAFE,               BYREF_IS_NULL,          IsNullRef, NoSig)
@@ -826,7 +816,7 @@ DEFINE_FIELD_U(rgiLastFrameFromForeignExceptionStackTrace,            StackFrame
 DEFINE_FIELD_U(iFrameCount,                StackFrameHelper,   iFrameCount)
 
 DEFINE_CLASS(STARTUP_HOOK_PROVIDER,  System,                StartupHookProvider)
-DEFINE_METHOD(STARTUP_HOOK_PROVIDER, PROCESS_STARTUP_HOOKS, ProcessStartupHooks, SM_RetVoid)
+DEFINE_METHOD(STARTUP_HOOK_PROVIDER, MANAGED_STARTUP, ManagedStartup, SM_RetVoid)
 
 DEFINE_CLASS(STREAM,                IO,                     Stream)
 DEFINE_METHOD(STREAM,               BEGIN_READ,             BeginRead,  IM_ArrByte_Int_Int_AsyncCallback_Object_RetIAsyncResult)

src/coreclr/vm/namespace.h

@@ -19,7 +19,6 @@
 #define g_CollectionsNS     g_SystemNS ".Collections"
 #define g_ResourcesNS       g_SystemNS ".Resources"
 #define g_DiagnosticsNS     g_SystemNS ".Diagnostics"
-#define g_DiagnosticsTracingNS g_DiagnosticsNS ".Tracing"
 #define g_CodeContractsNS   g_DiagnosticsNS ".Contracts"
 #define g_AssembliesNS      g_SystemNS ".Configuration.Assemblies"
 #define g_GlobalizationNS   g_SystemNS ".Globalization"

src/libraries/System.Private.CoreLib/src/System/StartupHookProvider.cs

@@ -11,7 +11,7 @@
 
 namespace System
 {
-    internal static class StartupHookProvider
+    internal partial static class StartupHookProvider
     {
         private const string StartupHookTypeName = "StartupHook";
         private const string InitializeMethodName = "Initialize";