From b306c03b3de293ad6cb0d0ed08ef87df9c7cc4e5 Mon Sep 17 00:00:00 2001
From: Rattenkrieg <shallowstack@gmail.com>
Date: Mon, 30 Nov 2020 00:06:22 +0300
Subject: [PATCH 1/2] conditionally assign (exact)contextHandle

---
 src/coreclr/src/jit/importer.cpp | 35 ++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/coreclr/src/jit/importer.cpp b/src/coreclr/src/jit/importer.cpp
index fb9e10c6a98093..00bf9d82c8e792 100644
--- a/src/coreclr/src/jit/importer.cpp
+++ b/src/coreclr/src/jit/importer.cpp
@@ -21195,12 +21195,43 @@ void Compiler::impDevirtualizeCall(GenTreeCall*            call,
     // the base in most other ways.
     *method        = derivedMethod;
     *methodFlags   = derivedMethodAttribs;
-    *contextHandle = MAKE_METHODCONTEXT(derivedMethod);
+
+    if (((SIZE_T)(*contextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_METHOD)
+    {
+        *contextHandle = MAKE_METHODCONTEXT(derivedMethod);
+    }
+    else
+    {
+        assert(((SIZE_T)(*contextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_CLASS);
+        if (isExact)
+        {
+            *contextHandle = MAKE_CLASSCONTEXT(objClass);
+        }
+        else
+        {
+            *contextHandle = MAKE_CLASSCONTEXT(derivedClass);
+        }
+    }
 
     // Update context handle.
     if ((exactContextHandle != nullptr) && (*exactContextHandle != nullptr))
     {
-        *exactContextHandle = MAKE_METHODCONTEXT(derivedMethod);
+        if (((SIZE_T)(*exactContextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_METHOD)
+        {
+            *exactContextHandle = MAKE_METHODCONTEXT(derivedMethod);
+        }
+        else
+        {
+            assert(((SIZE_T)(*exactContextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_CLASS);
+            if (isExact)
+            {
+                *exactContextHandle = MAKE_CLASSCONTEXT(objClass);
+            }
+            else
+            {
+                *exactContextHandle = MAKE_CLASSCONTEXT(derivedClass);
+            }
+        }
     }
 
 #ifdef FEATURE_READYTORUN_COMPILER

From a471905a40bfd72ffef962b2a02d39df7bdb7ecb Mon Sep 17 00:00:00 2001
From: Rattenkrieg <shallowstack@gmail.com>
Date: Mon, 30 Nov 2020 23:44:00 +0300
Subject: [PATCH 2/2] assign updated context when exactContextHandle pointing
 to nullptr

---
 src/coreclr/src/jit/importer.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/coreclr/src/jit/importer.cpp b/src/coreclr/src/jit/importer.cpp
index 00bf9d82c8e792..055918d16c619b 100644
--- a/src/coreclr/src/jit/importer.cpp
+++ b/src/coreclr/src/jit/importer.cpp
@@ -21193,8 +21193,8 @@ void Compiler::impDevirtualizeCall(GenTreeCall*            call,
     // https://github.com/dotnet/runtime/issues/38477
     // but hopefully the derived method conforms to
     // the base in most other ways.
-    *method        = derivedMethod;
-    *methodFlags   = derivedMethodAttribs;
+    *method      = derivedMethod;
+    *methodFlags = derivedMethodAttribs;
 
     if (((SIZE_T)(*contextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_METHOD)
     {
@@ -21214,7 +21214,7 @@ void Compiler::impDevirtualizeCall(GenTreeCall*            call,
     }
 
     // Update context handle.
-    if ((exactContextHandle != nullptr) && (*exactContextHandle != nullptr))
+    if ((exactContextHandle != nullptr))
     {
         if (((SIZE_T)(*exactContextHandle) & CORINFO_CONTEXTFLAGS_MASK) == CORINFO_CONTEXTFLAGS_METHOD)
         {