[turbofan] Introduce CheckHole and CheckHoleNaN operators.

src/compiler/effect-control-linearizer.cc

Index: src/compiler/effect-control-linearizer.cc
diff --git a/src/compiler/effect-control-linearizer.cc b/src/compiler/effect-control-linearizer.cc
index 98d6832afd51b83e387e80b7a22203a32b3c19b5..f68ebdf5f489ac85b8da41109fc2c0fa04c14ec1 100644
--- a/src/compiler/effect-control-linearizer.cc
+++ b/src/compiler/effect-control-linearizer.cc
@@ -455,6 +455,12 @@ bool EffectControlLinearizer::TryWireInStateEffect(Node* node,
     case IrOpcode::kCheckIf:
       state = LowerCheckIf(node, frame_state, *effect, *control);
       break;
+    case IrOpcode::kCheckHole:
+      state = LowerCheckHole(node, frame_state, *effect, *control);
+      break;
+    case IrOpcode::kCheckHoleNaN:
+      state = LowerCheckHoleNaN(node, frame_state, *effect, *control);
+      break;
     case IrOpcode::kPlainPrimitiveToNumber:
       state = LowerPlainPrimitiveToNumber(node, *effect, *control);
       break;
@@ -1296,6 +1302,51 @@ EffectControlLinearizer::LowerCheckIf(Node* node, Node* frame_state,
 }
 
 EffectControlLinearizer::ValueEffectControl
+EffectControlLinearizer::LowerCheckHole(Node* node, Node* frame_state,
+                                        Node* effect, Node* control) {
+  CheckHoleMode mode = CheckHoleModeOf(node->op());
+  Node* value = node->InputAt(0);
+  Node* check = graph()->NewNode(machine()->WordEqual(), value,
+                                 jsgraph()->TheHoleConstant());
+  switch (mode) {
+    case CheckHoleMode::kAllowReturnHole:

[Jarin, 2016/06/15 11:18:43]

This is confusing - it does not return hole, it turns hole into undefined. Could
we have a name that somehow implies that (Like kConvertHoleToUndefined or some
such)?

[Benedikt Meurer, 2016/06/15 11:39:09]

Done.

+      value = graph()->NewNode(
+          common()->Select(MachineRepresentation::kTagged, BranchHint::kFalse),
+          check, jsgraph()->UndefinedConstant(), value);
+      break;
+    case CheckHoleMode::kNeverReturnHole:
+      control = effect = graph()->NewNode(common()->DeoptimizeIf(), check,

[Jarin, 2016/06/15 11:18:43]

kDeoptimizeIfHole?

[Benedikt Meurer, 2016/06/15 11:39:09]

I kinda prefer the never-return-hole thing here.

+                                          frame_state, effect, control);
+      break;
+  }
+
+  // Make sure the lowered node does not appear in any use lists.
+  node->TrimInputCount(0);
+
+  return ValueEffectControl(value, effect, control);
+}
+
+EffectControlLinearizer::ValueEffectControl
+EffectControlLinearizer::LowerCheckHoleNaN(Node* node, Node* frame_state,
+                                           Node* effect, Node* control) {
+  // If we reach this point w/o eliminating the {node} that's marked
+  // with allow-return-hole, we cannot do anything, so just deoptimize
+  // in case of the hole NaN (similar to Crankshaft).
+  Node* value = node->InputAt(0);
+  Node* check = graph()->NewNode(
+      machine()->Word32Equal(),
+      graph()->NewNode(machine()->Float64ExtractHighWord32(), value),
+      jsgraph()->Int32Constant(kHoleNanUpper32));
+  control = effect = graph()->NewNode(common()->DeoptimizeIf(), check,
+                                      frame_state, effect, control);
+
+  // Make sure the lowered node does not appear in any use lists.
+  node->TrimInputCount(0);
+
+  return ValueEffectControl(value, effect, control);
+}
+
+EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::AllocateHeapNumberWithValue(Node* value, Node* effect,
                                                      Node* control) {
   Node* result = effect = graph()->NewNode(