1 files changed, 51 insertions, 0 deletions
diff --git a/src/vm/arm/jithelpersarm.cpp b/src/vm/arm/jithelpersarm.cpp
new file mode 100644
index 0000000000..40827dd712
--- /dev/null
+++ b/src/vm/arm/jithelpersarm.cpp
@@ -0,0 +1,51 @@
+// 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: JITHelpersARM.CPP
+// ===========================================================================
+
+// This contains JITinterface routines that are specific to the
+// ARM platform. They are modeled after the AMD64 specific routines
+// found in JIThelpersAMD64.cpp
+
+
+#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->R7 - offsetof(TailCallFrame, m_calleeSavedRegisters));
+}
+
+// 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));
+
+    // The return addres for the pseudo-call
+    pContext->Lr  = (DWORD_PTR)JIT_TailCallHelperStub_ReturnAddress;
+    // The R11/ETW chain 'frame' pointer
+    pContext->R11 = GetSP(pContext) - (2 * sizeof(DWORD)); // LR & R11
+    // The unwind data frame pointer
+    pContext->R7  = pContext->R11 - (7 * sizeof(DWORD)); // r4-R10 non-volatile registers
+    // for the args and the remainder of the FrameWithCookie<TailCallFrame>
+    SetSP(pContext, (size_t) pNewFrame - (cbNewArgArea + sizeof(GSCookie)));
+
+    // For popping the Frame, store the Thread
+    pContext->R6  = (DWORD_PTR)pThread;
+    // And the current head/top
+    pContext->R5  = (DWORD_PTR)pThread->GetFrame();
+
+    return pNewFrame;
+}
+