[turbofan] Remove typeof optimization from typed lowering.

Now that Ignition has the dedicated TestTypeOf operator, there's not
really a point in doing the typeof with abstract/strict equal combining
in TurboFan anymore. In fact it's counter-productive to do so, as it
might try to cover typeof comparisons in cases where it's better to just
compute the typeof once, i.e.:

  let x = typeof a, y = typeof b;
  if (x === y) {
    if (x === 'string') {
      ...
    }
  }

Here we would combine the second comparison into an ObjectIsString, and
still compute the typeof a.

R=jarin@chromium.org
BUG=v8:5267

Review-Url: https://codereview.chromium.org/2780953003
Cr-Commit-Position: refs/heads/master@{#44220}

src/compiler/js-typed-lowering.cc

@@ -842,63 +842,7 @@ Reduction JSTypedLowering::ReduceJSTypeOf(Node* node) {
   return NoChange();
 }
 
-Reduction JSTypedLowering::ReduceJSEqualTypeOf(Node* node) {
-  Node* input;
-  Handle<String> type;
-  HeapObjectBinopMatcher m(node);
-  if (m.left().IsJSTypeOf() && m.right().HasValue() &&
-      m.right().Value()->IsString()) {
-    input = m.left().InputAt(0);
-    type = Handle<String>::cast(m.right().Value());
-  } else if (m.right().IsJSTypeOf() && m.left().HasValue() &&
-             m.left().Value()->IsString()) {
-    input = m.right().InputAt(0);
-    type = Handle<String>::cast(m.left().Value());
-  } else {
-    return NoChange();
-  }
-  Node* value;
-  if (String::Equals(type, factory()->boolean_string())) {
-    value =
-        graph()->NewNode(common()->Select(MachineRepresentation::kTagged),
-                         graph()->NewNode(simplified()->ReferenceEqual(), input,
-                                          jsgraph()->TrueConstant()),
-                         jsgraph()->TrueConstant(),
-                         graph()->NewNode(simplified()->ReferenceEqual(), input,
-                                          jsgraph()->FalseConstant()));
-  } else if (String::Equals(type, factory()->function_string())) {
-    value = graph()->NewNode(simplified()->ObjectIsDetectableCallable(), input);
-  } else if (String::Equals(type, factory()->number_string())) {
-    value = graph()->NewNode(simplified()->ObjectIsNumber(), input);
-  } else if (String::Equals(type, factory()->object_string())) {
-    value = graph()->NewNode(
-        common()->Select(MachineRepresentation::kTagged),
-        graph()->NewNode(simplified()->ObjectIsNonCallable(), input),
-        jsgraph()->TrueConstant(),
-        graph()->NewNode(simplified()->ReferenceEqual(), input,
-                         jsgraph()->NullConstant()));
-  } else if (String::Equals(type, factory()->string_string())) {
-    value = graph()->NewNode(simplified()->ObjectIsString(), input);
-  } else if (String::Equals(type, factory()->symbol_string())) {
-    value = graph()->NewNode(simplified()->ObjectIsSymbol(), input);
-  } else if (String::Equals(type, factory()->undefined_string())) {
-    value = graph()->NewNode(
-        common()->Select(MachineRepresentation::kTagged),
-        graph()->NewNode(simplified()->ReferenceEqual(), input,
-                         jsgraph()->NullConstant()),
-        jsgraph()->FalseConstant(),
-        graph()->NewNode(simplified()->ObjectIsUndetectable(), input));
-  } else {
-    return NoChange();
-  }
-  ReplaceWithValue(node, value);
-  return Replace(value);
-}
-
 Reduction JSTypedLowering::ReduceJSEqual(Node* node) {
-  Reduction const reduction = ReduceJSEqualTypeOf(node);
-  if (reduction.Changed()) return reduction;
-
   JSBinopReduction r(this, node);
 
   if (r.BothInputsAre(Type::UniqueName())) {
@@ -961,9 +905,6 @@ Reduction JSTypedLowering::ReduceJSStrictEqual(Node* node) {
     }
   }
 
-  Reduction const reduction = ReduceJSEqualTypeOf(node);
-  if (reduction.Changed()) return reduction;
-
   if (r.BothInputsAre(Type::Unique())) {
     return r.ChangeToPureOperator(simplified()->ReferenceEqual());
   }

src/compiler/js-typed-lowering.h

@@ -57,7 +57,6 @@ class V8_EXPORT_PRIVATE JSTypedLowering final
   Reduction ReduceJSStoreContext(Node* node);
   Reduction ReduceJSLoadModule(Node* node);
   Reduction ReduceJSStoreModule(Node* node);
-  Reduction ReduceJSEqualTypeOf(Node* node);
   Reduction ReduceJSEqual(Node* node);
   Reduction ReduceJSStrictEqual(Node* node);
   Reduction ReduceJSToBoolean(Node* node);