[turbofan] Correctify JSToBoolean lowering.

src/compiler/simplified-operator-reducer.cc

Index: src/compiler/simplified-operator-reducer.cc
diff --git a/src/compiler/simplified-operator-reducer.cc b/src/compiler/simplified-operator-reducer.cc
index 0868cab3fc7e57d11a75b92a3e515ee927f4864b..9d45e5b19261c39f5492687aa828588b3a63054c 100644
--- a/src/compiler/simplified-operator-reducer.cc
+++ b/src/compiler/simplified-operator-reducer.cc
@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "src/compiler/simplified-operator-reducer.h"
+
+#include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-matchers.h"
-#include "src/compiler/simplified-operator-reducer.h"
+#include "src/compiler/node-properties-inl.h"
 
 namespace v8 {
 namespace internal {
@@ -20,6 +23,8 @@ SimplifiedOperatorReducer::~SimplifiedOperatorReducer() {}
 
 Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
   switch (node->opcode()) {
+    case IrOpcode::kAnyToBoolean:
+      return ReduceAnyToBoolean(node);
     case IrOpcode::kBooleanNot: {
       HeapObjectMatcher<HeapObject> m(node->InputAt(0));
       if (m.Is(Unique<HeapObject>::CreateImmovable(factory()->false_value()))) {
@@ -105,8 +110,36 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
 }
 
 
+Reduction SimplifiedOperatorReducer::ReduceAnyToBoolean(Node* node) {
+  Node* const input = NodeProperties::GetValueInput(node, 0);
+  Type* const input_type = NodeProperties::GetBounds(input).upper;
+  if (input_type->Is(Type::Boolean())) {
+    // AnyToBoolean(x:boolean) => x
+    return Replace(input);
+  }
+  if (input_type->Is(Type::OrderedNumber())) {
+    // AnyToBoolean(x:ordered-number) => BooleanNot(NumberEqual(x, #0))
+    Node* compare = graph()->NewNode(simplified()->NumberEqual(), input,
+                                     jsgraph()->ZeroConstant());
+    return Change(node, simplified()->BooleanNot(), compare);
+  }
+  if (input_type->Is(Type::String())) {
+    // AnyToBoolean(x:string) => BooleanNot(NumberEqual(x.length, #0))
+    FieldAccess const access = AccessBuilder::ForStringLength();
+    Node* length = graph()->NewNode(simplified()->LoadField(access), input,
+                                    graph()->start(), graph()->start());
+    Node* compare = graph()->NewNode(simplified()->NumberEqual(), length,
+                                     jsgraph()->ZeroConstant());
+    return Change(node, simplified()->BooleanNot(), compare);
+  }
+  return NoChange();
+}
+
+
 Reduction SimplifiedOperatorReducer::Change(Node* node, const Operator* op,
                                             Node* a) {
+  DCHECK_EQ(node->InputCount(), OperatorProperties::GetTotalInputCount(op));
+  DCHECK_LE(1, node->InputCount());
   node->set_op(op);
   node->ReplaceInput(0, a);
   return Changed(node);
@@ -141,6 +174,11 @@ Factory* SimplifiedOperatorReducer::factory() const {
 }
 
 
+CommonOperatorBuilder* SimplifiedOperatorReducer::common() const {
+  return jsgraph()->common();
+}
+
+
 MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
   return jsgraph()->machine();
 }