[turbofan] Respect effect input when lowering JSToBoolean for string inputs.

src/compiler/js-typed-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 678 matching lines @@
     NodeProperties::ChangeOp(node, simplified()->NumberEqual());
     return Changed(node);
   }
   return NoChange();
 }
 
 
 Reduction JSTypedLowering::ReduceJSToBoolean(Node* node) {
   Node* const input = node->InputAt(0);
   Type* const input_type = NodeProperties::GetType(input);
+  Node* const effect = NodeProperties::GetEffectInput(node);
   if (input_type->Is(Type::Boolean())) {
     // JSToBoolean(x:boolean) => x
-    ReplaceWithValue(node, input);
+    ReplaceWithValue(node, input, effect);
     return Replace(input);
   } else if (input_type->Is(Type::OrderedNumber())) {
     // JSToBoolean(x:ordered-number) => BooleanNot(NumberEqual(x,#0))
     RelaxEffectsAndControls(node);
     node->ReplaceInput(0, graph()->NewNode(simplified()->NumberEqual(), input,
                                            jsgraph()->ZeroConstant()));
     node->TrimInputCount(1);
     NodeProperties::ChangeOp(node, simplified()->BooleanNot());
     return Changed(node);
   } else if (input_type->Is(Type::String())) {
     // JSToBoolean(x:string) => NumberLessThan(#0,x.length)
     FieldAccess const access = AccessBuilder::ForStringLength(graph()->zone());
-    // It is safe for the load to be effect-free (i.e. not linked into effect
-    // chain) because we assume String::length to be immutable.
     Node* length = graph()->NewNode(simplified()->LoadField(access), input,
-                                    graph()->start(), graph()->start());
+                                    effect, graph()->start());
     ReplaceWithValue(node, node, length);
     node->ReplaceInput(0, jsgraph()->ZeroConstant());
     node->ReplaceInput(1, length);
     node->TrimInputCount(2);
     NodeProperties::ChangeOp(node, simplified()->NumberLessThan());
     return Changed(node);
   }
   return NoChange();
 }
 
@@ skipping 1113 matching lines @@
 }
 
 
 MachineOperatorBuilder* JSTypedLowering::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8