Lazy deopt:

runtime/vm/stack_frame.h

Index: runtime/vm/stack_frame.h
diff --git a/runtime/vm/stack_frame.h b/runtime/vm/stack_frame.h
index 9cc7bd573ef68598eff00ab0799f337509b6b4cc..48152b323db81986521dd181a0ec4a45e6773ddf 100644
--- a/runtime/vm/stack_frame.h
+++ b/runtime/vm/stack_frame.h
@@ -51,6 +51,18 @@ class StackFrame : public ValueObject {
     return 0;
   }
 
+  uword IsMarkedForLazyDeopt() const {
+    uword raw_pc = *reinterpret_cast<uword*>(
+        sp() + (kSavedPcSlotFromSp * kWordSize));
+    return raw_pc == StubCode::DeoptimizeLazyFromReturn_entry()->EntryPoint();
+  }
+  void MarkForLazyDeopt() {
+    set_pc(StubCode::DeoptimizeLazyFromReturn_entry()->EntryPoint());
+  }
+  void UnmarkForLazyDeopt() {

[Florian Schneider, 2016/10/04 21:32:41]

This reads a little weird: Maybe comment that pc_ is computed by consulting the
pending deopt table if necessary. Or can you use GetCallerPc directly here?

ASSERT(pc() != StubCode::DeoptimizeLazyFromReturn_entry()->EntryPoint());

[rmacnak, 2016/10/04 22:11:28]

Added comment and assert.  Can't use GetCallerPc here; pc_ in this frame came
from GetCallerPc on the callee frame in the iterator.

+    set_pc(pc());
+  }
+
   void set_pc(uword value) {
     *reinterpret_cast<uword*>(sp() + (kSavedPcSlotFromSp * kWordSize)) = value;
     pc_ = value;
@@ -362,6 +374,9 @@ class InlinedFunctionsIterator : public ValueObject {
 };
 
 
+void ValidateFrames();

[Florian Schneider, 2016/10/04 21:32:41]

#ifdef DEBUG

[rmacnak, 2016/10/04 22:11:28]

Done.

+
+
 #if !defined(TARGET_ARCH_DBC)
 DART_FORCE_INLINE static intptr_t LocalVarIndex(intptr_t fp_offset,
                                                 intptr_t var_index) {