ART: Single-frame deopt

Add deoptimization of a single frame. Works by removing the managed
code frame and jumping into the quick-to-interpreter bridge, and
the bridge understanding a stored ShadowFrame.

We need a separate fixup pass. For x86, we leave the return address
on the stack so we don't need to push it there.

Bug: 21611912
Change-Id: I06625685ced8b054244f8685ab50b238a705b9d2
diff --git a/runtime/arch/context.h b/runtime/arch/context.h
index 9ef761e..9af7c04 100644
--- a/runtime/arch/context.h
+++ b/runtime/arch/context.h
@@ -50,6 +50,9 @@
   // Sets the program counter value.
   virtual void SetPC(uintptr_t new_pc) = 0;
 
+  // Sets the first argument register.
+  virtual void SetArg0(uintptr_t new_arg0_value) = 0;
+
   // Returns whether the given GPR is accessible (read or write).
   virtual bool IsAccessibleGPR(uint32_t reg) = 0;