1 files changed, 67 insertions, 0 deletions
diff --git a/src/Native/System.Private.TypeLoader.Native/amd64/MethodEntrypointStubs.asm b/src/Native/System.Private.TypeLoader.Native/amd64/MethodEntrypointStubs.asm
new file mode 100644
index 000000000..f0c212b12
--- /dev/null
+++ b/src/Native/System.Private.TypeLoader.Native/amd64/MethodEntrypointStubs.asm
@@ -0,0 +1,67 @@
+;; Licensed to the .NET Foundation under one or more agreements.
+;; The .NET Foundation licenses this file to you under the MIT license.
+;; See the LICENSE file in the project root for more information.
+
+LEAF_ENTRY macro Name, Section
+    Section segment para 'CODE'
+    align   16
+    public  Name
+    Name    proc
+endm
+
+LEAF_END macro Name, Section
+    Name    endp
+    Section ends
+endm
+
+.data
+
+g_methodEntrypointThunk qword 0  ; The method which operates on universal transition
+g_universalTransition qword 0 ; The address of Redhawk's UniversalTransition thunk
+
+.code
+
+;  - TAILCALL_RAX: ("jmp rax") should be used for tailcalls, this emits an instruction 
+;            sequence which is recognized by the unwinder as a valid epilogue terminator
+TAILJMP_RAX TEXTEQU <DB 048h, 0FFh, 0E0h>
+
+PointerSize equ 8
+
+;;
+;; __jmpstub__MethodEntrypointStubs_CommonCallingStub(?)
+;;  Used when we dynamically need a VTableResolver not pre-generated
+;;
+;; r10 contains a pointer to a VTableResolverStruct
+;;   struct MethodEntryPointStubInfo
+;;   {
+;;       IntPtr targetCodePointer;
+;;       IntPtr MethodEntrypointStructPointer;
+;;   };
+;;
+LEAF_ENTRY __jmpstub__MethodEntrypointStubs_CommonCallingStub, _TEXT
+        ;; r10 <- stub info
+        mov rax, [r10]
+        cmp rax, 0
+        je SLOW_PATH
+        mov rax, [r10]
+        TAILJMP_RAX
+SLOW_PATH:
+        mov         r11, [r10 + 8]
+        mov         r10, g_methodEntrypointThunk
+        mov         rax, g_universalTransition
+        TAILJMP_RAX
+LEAF_END __jmpstub__MethodEntrypointStubs_CommonCallingStub, _TEXT
+
+;; Returns the size of the pre-generated thunks
+;; IntPtr MethodEntrypointStubs_SetupPointers(
+;;                          IntPtr universalTransition,
+;;                          IntPtr methodEntrypointThunk)
+;;
+LEAF_ENTRY MethodEntrypointStubs_SetupPointers, _TEXT
+        mov    g_universalTransition, rcx
+        mov    g_methodEntrypointThunk, rdx
+        lea    rax, [__jmpstub__MethodEntrypointStubs_CommonCallingStub]
+        ret
+LEAF_END MethodEntrypointStubs_SetupPointers, _TEXT
+
+end