DBC: Eager deoptimization and CheckSmi instruction.

runtime/vm/deopt_instructions.cc

Index: runtime/vm/deopt_instructions.cc
diff --git a/runtime/vm/deopt_instructions.cc b/runtime/vm/deopt_instructions.cc
index 1839f7fae8a14eb760f594f2148744adb99bc4f8..7594a16f947944928dbd57a6c8c1e20c5d01d0fa 100644
--- a/runtime/vm/deopt_instructions.cc
+++ b/runtime/vm/deopt_instructions.cc
@@ -67,13 +67,19 @@ DeoptContext::DeoptContext(const StackFrame* frame,
   // return-address. This section is copied as well, so that its contained
   // values can be updated before returning to the deoptimized function.
   // Note: on DBC stack grows upwards unlike on all other architectures.
+  const intptr_t frame_size =
+#if defined(TARGET_ARCH_DBC)
+      (static_cast<intptr_t>(frame->sp()) -

[Vyacheslav Egorov (Google), 2016/06/09 15:09:06]

I don't think these casts are needed really, they just make things look more
convoluted. 

You can add an assertion sp() < fp() and sp() > fp() for !DBC and DBC
respectively. 

[zra, 2016/06/09 16:42:23]

Done.

+       static_cast<intptr_t>(frame->fp())) / kWordSize;
+#else
+      (static_cast<intptr_t>(frame->fp()) -
+       static_cast<intptr_t>(frame->sp())) / kWordSize;
+#endif
+  ASSERT(frame_size >= 0);
+
   source_frame_size_ =
       + kDartFrameFixedSize  // For saved values below sp.
-#if !defined(TARGET_ARCH_DBC)
-      + ((frame->fp() - frame->sp()) / kWordSize)  // For frame size incl. sp.
-#else
-      + ((frame->sp() - frame->fp()) / kWordSize)  // For frame size incl. sp.
-#endif  // !defined(TARGET_ARCH_DBC)
+      + frame_size  // For frame size incl. sp.
       + 1  // For fp.
       + kParamEndSlotFromFp  // For saved values above fp.
       + num_args_;  // For arguments.