[Interpreter] Adds support for const/let variables to interpreter.

src/compiler/bytecode-graph-builder.cc

Index: src/compiler/bytecode-graph-builder.cc
diff --git a/src/compiler/bytecode-graph-builder.cc b/src/compiler/bytecode-graph-builder.cc
index f337a57c66209d75696e37dacc1796db8c4abaa2..042e0cbc730908b3205b89c508615799bdbe6f17 100644
--- a/src/compiler/bytecode-graph-builder.cc
+++ b/src/compiler/bytecode-graph-builder.cc
@@ -1513,6 +1513,20 @@ void BytecodeGraphBuilder::VisitStackCheck() {
   environment()->RecordAfterState(node, &states);
 }
 
+void BytecodeGraphBuilder::VisitJumpIfHole() {
+  BuildJumpIfEqual(jsgraph()->TheHoleConstant());
+}
+
+void BytecodeGraphBuilder::VisitJumpIfNotHole() {
+  Node* accumulator = environment()->LookupAccumulator();
+  Node* condition = NewNode(javascript()->StrictEqual(), accumulator,

[Michael Starzinger, 2016/02/08 11:54:08]

Can we use javascript()->StrictNotEqual() here? Or is there a particular reason
that wouldn't work in this case?

[mythria, 2016/02/08 13:22:33]

StrictNotEqual causes an assert fail here:
https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/ic/x64/ic-x...

According to my understanding, parser changes all strictNotEqual to stictEqual
and LogicalNot. So we don't see a strictNotEqual.

[Michael Starzinger, 2016/02/08 13:57:45]

Acknowledged. Ah, yeah, I have seen this before. I am fine with keeping this as
is, maybe I'll follow up on this at some point.

+                            jsgraph()->TheHoleConstant());
+  Node* node =
+      NewNode(common()->Select(MachineRepresentation::kTagged), condition,
+              jsgraph()->FalseConstant(), jsgraph()->TrueConstant());
+  BuildConditionalJump(node);
+}
+
 void BytecodeGraphBuilder::VisitReturn() {
   Node* control =
       NewNode(common()->Return(), environment()->LookupAccumulator());