Handle stack frames differently inside and on the boundary of wasm.

src/frames.cc

Index: src/frames.cc
diff --git a/src/frames.cc b/src/frames.cc
index 643ee69ce8fa3b6ba970d387574683f417707a95..55281bf7053f22b58e8f127d348d01885b50e635 100644
--- a/src/frames.cc
+++ b/src/frames.cc
@@ -458,7 +458,16 @@ StackFrame::Type StackFrame::ComputeType(const StackFrameIteratorBase* iterator,
       case Code::OPTIMIZED_FUNCTION:
         return OPTIMIZED;
       case Code::WASM_FUNCTION:
-        return WASM;
+        switch (code_obj->wasm_function_type()) {
+          case Code::WASM_INNER_FUNCTION:
+            return WASM;
+          case Code::WASM_TO_JS:
+            return WASM_TO_JS;
+          case Code::JS_TO_WASM:
+            return JS_TO_WASM;
+          default:
+            UNREACHABLE();

[JF, 2016/03/03 21:11:52]

You'll already get a warning if you don't cover all enumerators, because
wasm_function_type() returns an enum. I'd drop the default: any other value is
UB anyways.

[titzer, 2016/03/03 21:36:20]

Better safe than sorry. 

[JF, 2016/03/03 21:38:46]

Right, what I'm saying is that having `default: UNREACHABLE();` makes it a
runtime failure, whereas not having a default makes it a compile-time failure.

[bradn, 2016/03/03 21:39:10]

I'm not sure I share your trust in the compiler :-), given there is more than
one.

[JF, 2016/03/03 21:58:33]

All you need is one to give you the warning. The bots will do that. But eh, if
you'd rather fail at runtime I reserve the right to point and laugh :)

+        }
       case Code::BUILTIN:
         if (!marker->IsSmi()) {
           if (StandardFrame::IsArgumentsAdaptorFrame(state->fp)) {
@@ -707,12 +716,14 @@ void StandardFrame::IterateCompiledFrame(ObjectVisitor* v) const {
   // Visit the return address in the callee and incoming arguments.
   IteratePc(v, pc_address(), constant_pool_address(), code);
 
-  // Visit the context in stub frame and JavaScript frame.
-  // Visit the function in JavaScript frame.
-  Object** fixed_base = &Memory::Object_at(
-      fp() + StandardFrameConstants::kMarkerOffset);
-  Object** fixed_limit = &Memory::Object_at(fp());
-  v->VisitPointers(fixed_base, fixed_limit);
+  if (!is_wasm() && !is_wasm_to_js()) {
+    // Visit the context in stub frame and JavaScript frame.
+    // Visit the function in JavaScript frame.
+    Object** fixed_base =
+        &Memory::Object_at(fp() + StandardFrameConstants::kMarkerOffset);
+    Object** fixed_limit = &Memory::Object_at(fp());
+    v->VisitPointers(fixed_base, fixed_limit);
+  }
 }