JIT: Devirtualize non-shared generic virtual methods

src/coreclr/inc/corinfo.h

@@ -1540,7 +1540,7 @@ enum CORINFO_DEVIRTUALIZATION_DETAIL
 {
     CORINFO_DEVIRTUALIZATION_UNKNOWN,                              // no details available
     CORINFO_DEVIRTUALIZATION_SUCCESS,                              // devirtualization was successful
-    CORINFO_DEVIRTUALIZATION_FAILED_CANON,                         // object class was canonical
+    CORINFO_DEVIRTUALIZATION_FAILED_CANON,                         // object class or method was canonical
     CORINFO_DEVIRTUALIZATION_FAILED_COM,                           // object class was com
     CORINFO_DEVIRTUALIZATION_FAILED_CAST,                          // object class could not be cast to interface class
     CORINFO_DEVIRTUALIZATION_FAILED_LOOKUP,                        // interface method could not be found
@@ -1556,6 +1556,7 @@ enum CORINFO_DEVIRTUALIZATION_DETAIL
     CORINFO_DEVIRTUALIZATION_FAILED_DUPLICATE_INTERFACE,           // crossgen2 virtual method algorithm and runtime algorithm differ in the presence of duplicate interface implementations
     CORINFO_DEVIRTUALIZATION_FAILED_DECL_NOT_REPRESENTABLE,        // Decl method cannot be represented in R2R image
     CORINFO_DEVIRTUALIZATION_FAILED_TYPE_EQUIVALENCE,              // Support for type equivalence in devirtualization is not yet implemented in crossgen2
+    CORINFO_DEVIRTUALIZATION_FAILED_GENERIC_VIRTUAL,               // Devirtualization of generic virtual methods is not yet implemented in crossgen2
     CORINFO_DEVIRTUALIZATION_COUNT,                                // sentinel for maximum value
 };
 
@@ -1578,7 +1579,7 @@ struct CORINFO_DEVIRTUALIZATION_INFO
     // - If pResolvedTokenDevirtualizedMethod is not set to NULL and targeting an R2R image
     //   use it as the parameter to getCallInfo
     // - isInstantiatingStub is set to TRUE if the devirtualized method is a generic method instantiating stub
-    // - wasArrayInterfaceDevirt is set TRUE for array interface method devirtualization
+    // - needsMethodContext is set TRUE if the devirtualized method may require a method context
     //     (in which case the method handle and context will be a generic method)
     //
     CORINFO_METHOD_HANDLE           devirtualizedMethod;
@@ -1587,7 +1588,7 @@ struct CORINFO_DEVIRTUALIZATION_INFO
     CORINFO_RESOLVED_TOKEN          resolvedTokenDevirtualizedMethod;
     CORINFO_RESOLVED_TOKEN          resolvedTokenDevirtualizedUnboxedMethod;
     bool                            isInstantiatingStub;
-    bool                            wasArrayInterfaceDevirt;
+    bool                            needsMethodContext;
 };
 
 //----------------------------------------------------------------------------

src/coreclr/inc/jiteeversionguid.h

@@ -37,11 +37,11 @@
 
 #include <minipal/guid.h>
 
-constexpr GUID JITEEVersionIdentifier = { /* d1188f9b-d81e-487a-b525-cedb10d15c8e */
-    0xd1188f9b,
-    0xd81e,
-    0x487a,
-    {0xb5, 0x25, 0xce, 0xdb, 0x10, 0xd1, 0x5c, 0x8e}
+constexpr GUID JITEEVersionIdentifier = { /* cc48149b-7cb0-404a-9e9a-3d1623bb6194 */
+    0xcc48149b,
+    0x7cb0,
+    0x404a,
+    {0x9e, 0x9a, 0x3d, 0x16, 0x23, 0xbb, 0x61, 0x94}
   };
 
 #endif // JIT_EE_VERSIONING_GUID_H

src/coreclr/jit/compiler.cpp

@@ -10590,6 +10590,8 @@ const char* Compiler::devirtualizationDetailToString(CORINFO_DEVIRTUALIZATION_DE
             return "Decl method cannot be represented in R2R image";
         case CORINFO_DEVIRTUALIZATION_FAILED_TYPE_EQUIVALENCE:
             return "Support for type equivalence in devirtualization is not yet implemented in crossgen2";
+        case CORINFO_DEVIRTUALIZATION_FAILED_GENERIC_VIRTUAL:
+            return "Devirtualization of generic virtual methods is not yet implemented in crossgen2";
         default:
             return "undefined";
     }

src/coreclr/jit/fginline.cpp

@@ -544,32 +544,6 @@ class SubstitutePlaceholdersAndDevirtualizeWalker : public GenTreeVisitor<Substi
     }
 #endif // FEATURE_MULTIREG_RET
 
-    CORINFO_METHOD_HANDLE GetMethodHandle(GenTreeCall* call)
-    {
-        assert(call->IsDevirtualizationCandidate(m_compiler));
-        if (call->IsVirtual())
-        {
-            return call->gtCallMethHnd;
-        }
-        else
-        {
-            GenTree* runtimeMethHndNode =
-                call->gtCallAddr->AsCall()->gtArgs.FindWellKnownArg(WellKnownArg::RuntimeMethodHandle)->GetNode();
-            assert(runtimeMethHndNode != nullptr);
-            switch (runtimeMethHndNode->OperGet())
-            {
-                case GT_RUNTIMELOOKUP:
-                    return runtimeMethHndNode->AsRuntimeLookup()->GetMethodHandle();
-                case GT_CNS_INT:
-                    return CORINFO_METHOD_HANDLE(runtimeMethHndNode->AsIntCon()->IconValue());
-                default:
-                    assert(!"Unexpected type in RuntimeMethodHandle arg.");
-                    return nullptr;
-            }
-            return nullptr;
-        }
-    }
-
     //------------------------------------------------------------------------
     // LateDevirtualization: re-examine calls after inlining to see if we
     //   can do more devirtualization
@@ -612,9 +586,9 @@ class SubstitutePlaceholdersAndDevirtualizeWalker : public GenTreeVisitor<Substi
 
         if (tree->OperIs(GT_CALL))
         {
-            GenTreeCall* call = tree->AsCall();
-            // TODO-CQ: Drop `call->gtCallType == CT_USER_FUNC` once we have GVM devirtualization
-            bool tryLateDevirt = call->IsDevirtualizationCandidate(m_compiler) && (call->gtCallType == CT_USER_FUNC);
+            GenTreeCall*          call          = tree->AsCall();
+            CORINFO_METHOD_HANDLE method        = NO_METHOD_HANDLE;
+            bool                  tryLateDevirt = call->IsDevirtualizationCandidate(m_compiler, &method);
 
 #ifdef DEBUG
             tryLateDevirt = tryLateDevirt && (JitConfig.JitEnableLateDevirtualization() == 1);
@@ -632,11 +606,12 @@ class SubstitutePlaceholdersAndDevirtualizeWalker : public GenTreeVisitor<Substi
 
                 CORINFO_CONTEXT_HANDLE context                = call->gtLateDevirtualizationInfo->exactContextHnd;
                 InlineContext*         inlinersContext        = call->gtLateDevirtualizationInfo->inlinersContext;
-                CORINFO_METHOD_HANDLE  method                 = GetMethodHandle(call);
                 unsigned               methodFlags            = 0;
                 const bool             isLateDevirtualization = true;
                 const bool             explicitTailCall       = call->IsTailPrefixedCall();
 
+                assert(method != NO_METHOD_HANDLE);
+
                 CORINFO_CONTEXT_HANDLE contextInput = context;
                 context                             = nullptr;
                 m_compiler->impDevirtualizeCall(call, nullptr, &method, &methodFlags, &contextInput, &context,

src/coreclr/jit/gentree.cpp

@@ -2367,16 +2367,50 @@ int GenTreeCall::GetNonStandardAddedArgCount(Compiler* compiler) const
 //                              is devirtualized.
 //
 // Arguments:
-//     compiler - the compiler instance so that we can call eeFindHelper
+//     compiler    - [In]  the compiler instance so that we can call eeFindHelper
+//     pMethHandle - [Out] the method handle if the call is a devirtualization candidate
 //
 // Return Value:
 //     Returns true if this GT_CALL node is a devirtualization candidate.
 //
-bool GenTreeCall::IsDevirtualizationCandidate(Compiler* compiler) const
+bool GenTreeCall::IsDevirtualizationCandidate(Compiler* compiler, CORINFO_METHOD_HANDLE* pMethHandle) const
 {
-    return IsVirtual() ||
-           (gtCallType == CT_INDIRECT && (gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_VIRTUAL_FUNC_PTR) ||
-                                          gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_GVMLOOKUP_FOR_SLOT)));
+    CORINFO_METHOD_HANDLE methHandleToDevirt = NO_METHOD_HANDLE;
+    bool                  isDevirtCandidate  = false;
+
+    if (IsVirtual() && gtCallType == CT_USER_FUNC)
+    {
+        methHandleToDevirt = gtCallMethHnd;
+        isDevirtCandidate  = true;
+    }
+    else if (IsGenericVirtual(compiler) && (JitConfig.JitEnableGenericVirtualDevirtualization() != 0))
+    {
+        GenTree* runtimeMethHndNode =
+            gtCallAddr->AsCall()->gtArgs.FindWellKnownArg(WellKnownArg::RuntimeMethodHandle)->GetNode();
+        assert(runtimeMethHndNode != nullptr);
+        switch (runtimeMethHndNode->OperGet())
+        {
+            case GT_RUNTIMELOOKUP:
+                methHandleToDevirt = runtimeMethHndNode->AsRuntimeLookup()->GetMethodHandle();
+                isDevirtCandidate  = true;
+                break;
+            case GT_CNS_INT:
+                methHandleToDevirt = CORINFO_METHOD_HANDLE(runtimeMethHndNode->AsIntCon()->gtCompileTimeHandle);
+                isDevirtCandidate  = true;
+                break;
+            default:
+                // Unable to get method handle for devirtualization.
+                // This can happen if the method handle is not an RUNTIMELOOKUP or CNS_INT for generic virtuals,
+                break;
+        }
+    }
+
+    if (pMethHandle)
+    {
+        *pMethHandle = methHandleToDevirt;
+    }
+
+    return isDevirtCandidate;
 }
 
 //-------------------------------------------------------------------------

src/coreclr/jit/gentree.h

@@ -5260,8 +5260,13 @@ struct GenTreeCall final : public GenTree
     {
         return (gtFlags & GTF_CALL_VIRT_KIND_MASK) == GTF_CALL_VIRT_VTABLE;
     }
+    bool IsGenericVirtual(Compiler* compiler) const
+    {
+        return (gtCallType == CT_INDIRECT && (gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_VIRTUAL_FUNC_PTR) ||
+                                              gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_GVMLOOKUP_FOR_SLOT)));
+    }
 
-    bool IsDevirtualizationCandidate(Compiler* compiler) const;
+    bool IsDevirtualizationCandidate(Compiler* compiler, CORINFO_METHOD_HANDLE* pMethHandle = nullptr) const;
 
     bool IsInlineCandidate() const
     {