1 files changed, 48 insertions, 0 deletions
diff --git a/src/vm/amd64/jithelpersamd64.cpp b/src/vm/amd64/jithelpersamd64.cpp
new file mode 100644
index 0000000000..8f0a889fde
--- /dev/null
+++ b/src/vm/amd64/jithelpersamd64.cpp
@@ -0,0 +1,48 @@
+// 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.
+// ===========================================================================
+// File: JITHelpers.CPP
+// ===========================================================================
+
+// This contains JITinterface routines that are specific to the
+// AMD64 platform. They are modeled after the X86 specific routines
+// found in JIThelp.asm
+
+
+#include "common.h"
+#include "jitinterface.h"
+#include "eeconfig.h"
+#include "excep.h"
+#include "ecall.h"
+#include "asmconstants.h"
+
+EXTERN_C void JIT_TailCallHelperStub_ReturnAddress();
+
+TailCallFrame * TailCallFrame::GetFrameFromContext(CONTEXT * pContext)
+{
+    _ASSERTE((void*)::GetIP(pContext) == JIT_TailCallHelperStub_ReturnAddress);
+    return (TailCallFrame*)(pContext->R13 + sizeof(GSCookie));
+}
+
+// Assuming pContext is a plain generic call-site, adjust it to look like
+// it called into TailCallHelperStub, and is at the point of the call.
+TailCallFrame * TailCallFrame::AdjustContextForTailCallHelperStub(CONTEXT * pContext, size_t cbNewArgArea, Thread * pThread)
+{
+    TailCallFrame * pNewFrame = (TailCallFrame *)(GetSP(pContext) - sizeof(TailCallFrame));
+
+    // R13 is the frame pointer (for popping the stack)
+    pContext->R13 = (size_t)pNewFrame - sizeof(GSCookie);
+    // R12 is the previous stack pointer, so we can determine if a return buffer from the
+    // immediate caller (and thus being discarded via the tail call), or someplace else
+    pContext->R12 = GetSP(pContext);
+    // for the args and pushed return address of the 'call'
+    SetSP(pContext, (size_t)pNewFrame - (cbNewArgArea + sizeof(void*) + sizeof(GSCookie)));
+
+    // For popping the Frame, store the Thread
+    pContext->R14 = (DWORD_PTR)pThread;
+    // And the current head/top
+    pContext->R15 = (DWORD_PTR)pThread->GetFrame(); // m_Next
+
+    return (TailCallFrame *) pNewFrame;
+}