Support devirtualizing non-shared GVMs in R2R (#123183)

Implement the support for GVM devirtualization in managed type system.

It shares the same issue in #122023 where we are still not able to
devirt shared GVMs due to lacking a proper generic context, so let's do
the non-shared case first.

NativeAOT still not supported yet as it requires some work in the JIT to
stop spilling the helper call for fat pointers.

Contributes to #112596

/cc: @MichalStrehovsky @jakobbotsch

---------

Co-authored-by: Copilot <[email protected]>

Author: hez2010

src/coreclr/inc/corinfo.h

@@ -1558,7 +1558,6 @@ 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
 };
 

src/coreclr/inc/jiteeversionguid.h

@@ -37,11 +37,11 @@
 
 #include <minipal/guid.h>
 
-constexpr GUID JITEEVersionIdentifier = { /* 9068c4e3-6a0a-4347-a754-9ff2d63a1207 */
-    0x9068c4e3,
-    0x6a0a,
-    0x4347,
-    {0xa7, 0x54, 0x9f, 0xf2, 0xd6, 0x3a, 0x12, 0x07}
+constexpr GUID JITEEVersionIdentifier = { /* c10e2acf-7c94-4c61-b895-5178602e0e1e */
+    0xc10e2acf,
+    0x7c94,
+    0x4c61,
+    {0xb8, 0x95, 0x51, 0x78, 0x60, 0x2e, 0x0e, 0x1e}
   };
 
 #endif // JIT_EE_VERSIONING_GUID_H

src/coreclr/jit/compiler.cpp

@@ -10482,7 +10482,7 @@ const char* Compiler::devirtualizationDetailToString(CORINFO_DEVIRTUALIZATION_DE
         case CORINFO_DEVIRTUALIZATION_SUCCESS:
             return "success";
         case CORINFO_DEVIRTUALIZATION_FAILED_CANON:
-            return "object class was canonical";
+            return "object class or method was canonical";
         case CORINFO_DEVIRTUALIZATION_FAILED_COM:
             return "object class was com";
         case CORINFO_DEVIRTUALIZATION_FAILED_CAST:
@@ -10516,8 +10516,6 @@ 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/gentree.h

@@ -5275,8 +5275,13 @@ struct GenTreeCall final : public GenTree
     }
     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)));
+        return (gtCallType == CT_INDIRECT &&
+                (gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_VIRTUAL_FUNC_PTR) ||
+                 gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_GVMLOOKUP_FOR_SLOT)
+#ifdef FEATURE_READYTORUN
+                 || gtCallAddr->IsHelperCall(compiler, CORINFO_HELP_READYTORUN_VIRTUAL_FUNC_PTR)
+#endif
+                     ));
     }
 
     bool IsDevirtualizationCandidate(Compiler* compiler) const;

src/coreclr/tools/Common/Compiler/DevirtualizationManager.cs

@@ -66,6 +66,7 @@ protected virtual MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefType
         {
             devirtualizationDetail = CORINFO_DEVIRTUALIZATION_DETAIL.CORINFO_DEVIRTUALIZATION_UNKNOWN;
 
+            MethodDesc originalDeclMethod = declMethod;
             MethodDesc impl;
 
             if (declMethod.OwningType.IsInterface)
@@ -100,9 +101,19 @@ protected virtual MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefType
                 }
 
                 impl = implType.ResolveInterfaceMethodTargetWithVariance(declMethod);
+
                 if (impl != null)
                 {
                     impl = implType.FindVirtualFunctionTargetMethodOnObjectType(impl);
+
+                    // We need to bring the original instantiation back so that we can still try devirtualizing
+                    // when the method is a generic virtual method
+                    if (impl != null && originalDeclMethod.HasInstantiation)
+                    {
+                        // We may end up with a method that has substituted type parameters, so we need to instantiate
+                        // on the method definition
+                        impl = impl.GetMethodDefinition().MakeInstantiatedMethod(originalDeclMethod.Instantiation);
+                    }
                 }
                 else
                 {
@@ -178,9 +189,19 @@ protected virtual MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefType
                 }
 
                 impl = implType.FindVirtualFunctionTargetMethodOnObjectType(declMethod);
+
+                // We need to bring the original instantiation back so that we can still try devirtualizing
+                // when the method is a generic virtual method
+                if (impl != null && originalDeclMethod.HasInstantiation)
+                {
+                    // We may end up with a method that has substituted type parameters, so we need to instantiate
+                    // on the method definition
+                    impl = impl.GetMethodDefinition().MakeInstantiatedMethod(originalDeclMethod.Instantiation);
+                }
+
                 if (impl != null && (impl != declMethod))
                 {
-                    MethodDesc slotDefiningMethodImpl = MetadataVirtualMethodAlgorithm.FindSlotDefiningMethodForVirtualMethod(impl);
+                    MethodDesc slotDefiningMethodImpl = MetadataVirtualMethodAlgorithm.FindSlotDefiningMethodForVirtualMethod(impl.GetMethodDefinition());
                     MethodDesc slotDefiningMethodDecl = MetadataVirtualMethodAlgorithm.FindSlotDefiningMethodForVirtualMethod(declMethod);
 
                     if (slotDefiningMethodImpl != slotDefiningMethodDecl)
@@ -198,6 +219,13 @@ protected virtual MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefType
                 }
             }
 
+            if (impl != null && impl.HasInstantiation && impl.GetCanonMethodTarget(CanonicalFormKind.Specific).IsCanonicalMethod(CanonicalFormKind.Specific))
+            {
+                // We don't support devirtualization of shared generic virtual methods yet.
+                devirtualizationDetail = CORINFO_DEVIRTUALIZATION_DETAIL.CORINFO_DEVIRTUALIZATION_FAILED_CANON;
+                impl = null;
+            }
+
             return impl;
         }
 

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

@@ -1340,13 +1340,6 @@ private bool resolveVirtualMethod(CORINFO_DEVIRTUALIZATION_INFO* info)
             // Transform from the unboxing thunk to the normal method
             decl = decl.IsUnboxingThunk() ? decl.GetUnboxedMethod() : decl;
 
-            if (decl.HasInstantiation)
-            {
-                // We cannot devirtualize generic virtual methods in AOT yet
-                info->detail = CORINFO_DEVIRTUALIZATION_DETAIL.CORINFO_DEVIRTUALIZATION_FAILED_GENERIC_VIRTUAL;
-                return false;
-            }
-
             if ((info->context != null) && decl.OwningType.IsInterface)
             {
                 TypeDesc ownerTypeDesc = typeFromContext(info->context);

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

@@ -1126,7 +1126,7 @@ public 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
@@ -1142,7 +1142,6 @@ public 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
     }
 

src/coreclr/vm/jitinterface.cpp

@@ -14298,6 +14298,20 @@ BOOL LoadDynamicInfoEntry(Module *currentModule,
                 }
             }
 
+            // Strip off method instantiation for comparison if the method is generic virtual.
+            if (pDeclMethod->HasMethodInstantiation())
+            {
+                if (pImplMethodRuntime != NULL)
+                {
+                    pImplMethodRuntime = pImplMethodRuntime->StripMethodInstantiation();
+                }
+
+                if (pImplMethodCompiler != NULL)
+                {
+                    pImplMethodCompiler = pImplMethodCompiler->StripMethodInstantiation();
+                }
+            }
+
             if (pImplMethodRuntime != pImplMethodCompiler)
             {
                 if (kind == READYTORUN_FIXUP_Check_VirtualFunctionOverride)