Intrinsify typeof(T).GetGenericTypeDefinition()

src/coreclr/inc/corinfo.h

@@ -2082,6 +2082,22 @@ class ICorStaticInfo
         CORINFO_METHOD_HANDLE meth1Hnd,
         CORINFO_METHOD_HANDLE meth2Hnd) = 0;
 
+    //------------------------------------------------------------------------------
+    // getTypeDefinition: Get the (unconstructed) type definition from a given type handle.
+    //
+    // Arguments:
+    //    type - The input type handle
+    //
+    // Return Value:
+    //   The type handle for the (unconstructed) type definition from type.
+    //
+    // Remarks:
+    //   This is equivalent of Type.GetGenericTypeDefinition(). Given a generic type handle, it will
+    //   return the original type definition (eg. for Foo<int> it will return Foo<>). If called with
+    //   an unconstructed generic type, the method returns the same type as the input. This method
+    //   should only be called when the input type is in fact a generic type.
+    virtual CORINFO_CLASS_HANDLE getTypeDefinition(CORINFO_CLASS_HANDLE type) = 0;
+
     // Decides if you have any limitations for inlining. If everything's OK, it will return
     // INLINE_PASS.
     //

src/coreclr/inc/icorjitinfoimpl_generated.h

@@ -48,6 +48,9 @@ bool haveSameMethodDefinition(
           CORINFO_METHOD_HANDLE meth1Hnd,
           CORINFO_METHOD_HANDLE meth2Hnd) override;
 
+CORINFO_CLASS_HANDLE getTypeDefinition(
+          CORINFO_CLASS_HANDLE type) override;
+
 CorInfoInline canInline(
           CORINFO_METHOD_HANDLE callerHnd,
           CORINFO_METHOD_HANDLE calleeHnd) override;

src/coreclr/inc/jiteeversionguid.h

@@ -43,11 +43,11 @@ typedef const GUID *LPCGUID;
 #define GUID_DEFINED
 #endif // !GUID_DEFINED
 
-constexpr GUID JITEEVersionIdentifier = { /* 64fe30fb-0a27-4b1d-b89e-306e552ac848 */
-    0x64fe30fb,
-    0x0a27,
-    0x4b1d,
-    {0xb8, 0x9e, 0x30, 0x6e, 0x55, 0x2a, 0xc8, 0x48}
+constexpr GUID JITEEVersionIdentifier = { /* 273ba350-32bf-4714-beb0-7fa46c11364d */
+    0x273ba350,
+    0x32bf,
+    0x4714,
+    {0xbe, 0xb0, 0x7f, 0xa4, 0x6c, 0x11, 0x36, 0x4d}
   };
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////////

src/coreclr/jit/ICorJitInfo_names_generated.h

@@ -11,6 +11,7 @@ DEF_CLR_API(setMethodAttribs)
 DEF_CLR_API(getMethodSig)
 DEF_CLR_API(getMethodInfo)
 DEF_CLR_API(haveSameMethodDefinition)
+DEF_CLR_API(getTypeDefinition)
 DEF_CLR_API(canInline)
 DEF_CLR_API(beginInlining)
 DEF_CLR_API(reportInliningDecision)

src/coreclr/jit/ICorJitInfo_wrapper_generated.hpp

@@ -79,6 +79,15 @@ bool WrapICorJitInfo::haveSameMethodDefinition(
     return temp;
 }
 
+CORINFO_CLASS_HANDLE WrapICorJitInfo::getTypeDefinition(
+          CORINFO_CLASS_HANDLE type)
+{
+    API_ENTER(getTypeDefinition);
+    CORINFO_CLASS_HANDLE temp = wrapHnd->getTypeDefinition(type);
+    API_LEAVE(getTypeDefinition);
+    return temp;
+}
+
 CorInfoInline WrapICorJitInfo::canInline(
           CORINFO_METHOD_HANDLE callerHnd,
           CORINFO_METHOD_HANDLE calleeHnd)

src/coreclr/jit/compiler.h

@@ -4589,6 +4589,7 @@ class Compiler
 #endif
     void impResetLeaveBlock(BasicBlock* block, unsigned jmpAddr);
     GenTree* impTypeIsAssignable(GenTree* typeTo, GenTree* typeFrom);
+    GenTree* impGetGenericTypeDefinition(GenTree* type);
 
     // Mirrors StringComparison.cs
     enum StringComparison

src/coreclr/jit/fgbasic.cpp

@@ -1387,6 +1387,7 @@ void Compiler::fgFindJumpTargets(const BYTE* codeAddr, IL_OFFSET codeSize, Fixed
                             case NI_System_Type_get_IsByRefLike:
                             case NI_System_Type_get_IsGenericType:
                             case NI_System_Type_GetTypeFromHandle:
+                            case NI_System_Type_GetGenericTypeDefinition:
                             case NI_System_String_get_Length:
                             case NI_System_Buffers_Binary_BinaryPrimitives_ReverseEndianness:
 #if defined(FEATURE_HW_INTRINSICS)

src/coreclr/jit/importer.cpp

@@ -2490,6 +2490,42 @@ GenTree* Compiler::impTypeIsAssignable(GenTree* typeTo, GenTree* typeFrom)
     return nullptr;
 }
 
+//------------------------------------------------------------------------
+// impGetGenericTypeDefinition: gets the generic type definition from a 'typeof' expression.
+//
+// Arguments:
+//    type - The 'GenTree' node to inspect.
+//
+// Notes:
+//    If successful, this method will call 'impPopStack()' before returning.
+//
+GenTree* Compiler::impGetGenericTypeDefinition(GenTree* type)
+{
+    // This intrinsic requires the first arg to be some `typeof()` expression,
+    // ie. it applies to cases such as `typeof(...).GetGenericTypeDefinition()`.
+    CORINFO_CLASS_HANDLE hClassType = NO_CLASS_HANDLE;
+    if (gtIsTypeof(type, &hClassType))
+    {
+        // Check that the 'typeof()' expression is being used on a type that is in fact generic.
+        // If that is not the case, we don't expand the intrinsic. This will end up using
+        // the usual Type.GetGenericTypeDefinition() at runtime, which will throw in this case.
+        if (info.compCompHnd->getTypeInstantiationArgument(hClassType, 0) != NO_CLASS_HANDLE)
+        {
+            CORINFO_CLASS_HANDLE hClassResult = info.compCompHnd->getTypeDefinition(hClassType);
+
+            GenTree* handle  = gtNewIconEmbClsHndNode(hClassResult);
+            GenTree* retNode = gtNewHelperCallNode(CORINFO_HELP_TYPEHANDLE_TO_RUNTIMETYPE, TYP_REF, handle);
+
+            // Drop the typeof(T) node
+            impPopStack();
+
+            return retNode;
+        }
+    }
+
+    return nullptr;
+}
+
 /*****************************************************************************
  * 'logMsg' is true if a log message needs to be logged. false if the caller has
  *   already logged it (presumably in a more detailed fashion than done here)

src/coreclr/jit/importercalls.cpp

@@ -3321,6 +3321,9 @@ GenTree* Compiler::impIntrinsic(CORINFO_CLASS_HANDLE    clsHnd,
             case NI_System_Type_op_Equality:
             case NI_System_Type_op_Inequality:
 
+            // This allows folding "typeof(...).GetGenericTypeDefinition() == typeof(...)"
+            case NI_System_Type_GetGenericTypeDefinition:
+
             // These may lead to early dead code elimination
             case NI_System_Type_get_IsValueType:
             case NI_System_Type_get_IsPrimitive:
@@ -3856,6 +3859,14 @@ GenTree* Compiler::impIntrinsic(CORINFO_CLASS_HANDLE    clsHnd,
                 break;
             }
 
+            case NI_System_Type_GetGenericTypeDefinition:
+            {
+                GenTree* type = impStackTop(0).val;
+
+                retNode = impGetGenericTypeDefinition(type);
+                break;
+            }
+
             case NI_System_Type_op_Equality:
             case NI_System_Type_op_Inequality:
             {
@@ -10220,6 +10231,10 @@ NamedIntrinsic Compiler::lookupNamedIntrinsic(CORINFO_METHOD_HANDLE method)
                         {
                             result = NI_System_Type_GetTypeFromHandle;
                         }
+                        else if (strcmp(methodName, "GetGenericTypeDefinition") == 0)
+                        {
+                            result = NI_System_Type_GetGenericTypeDefinition;
+                        }
                         else if (strcmp(methodName, "IsAssignableFrom") == 0)
                         {
                             result = NI_System_Type_IsAssignableFrom;

src/coreclr/jit/namedintrinsiclist.h

@@ -89,6 +89,7 @@ enum NamedIntrinsic : unsigned short
     NI_System_Type_op_Equality,
     NI_System_Type_op_Inequality,
     NI_System_Type_GetTypeFromHandle,
+    NI_System_Type_GetGenericTypeDefinition,
     NI_System_Array_Clone,
     NI_System_Array_GetLength,
     NI_System_Array_GetLowerBound,

src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs

@@ -1248,6 +1248,11 @@ private bool haveSameMethodDefinition(CORINFO_METHOD_STRUCT_* methHnd1, CORINFO_
             return meth1.GetTypicalMethodDefinition() == meth2.GetTypicalMethodDefinition();
         }
 
+        private CORINFO_CLASS_STRUCT_* getTypeDefinition(CORINFO_CLASS_STRUCT_* type)
+        {
+            return ObjectToHandle(HandleToObject(type).GetTypeDefinition());
+        }
+
         private CorInfoInline canInline(CORINFO_METHOD_STRUCT_* callerHnd, CORINFO_METHOD_STRUCT_* calleeHnd)
         {
             MethodDesc callerMethod = HandleToObject(callerHnd);