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

This allows us to re-enable the mjsunit/tools/profile test case.

R=jarin@chromium.org
BUG=v8:4493
LOG=n

Review URL: https://codereview.chromium.org/1418643002

Cr-Commit-Position: refs/heads/master@{#31416}

src/compiler/js-typed-lowering.cc

@@ -696,9 +696,10 @@ Reduction JSTypedLowering::ReduceJSUnaryNot(Node* node) {
 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))
@@ -711,10 +712,8 @@ Reduction JSTypedLowering::ReduceJSToBoolean(Node* 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);

test/mjsunit/mjsunit.status

@@ -154,7 +154,6 @@
 
   # Issue 4493: Bugs due to --turbo-inlining.
   'harmony/reflect': [PASS, NO_VARIANTS],
-  'tools/profile': [PASS, NO_VARIANTS],
 
   # Assumptions about optimization need investigation in TurboFan.
   'compiler/inlined-call': [PASS, NO_VARIANTS],

test/mjsunit/regress/regress-4493-1.js

+// Copyright 2015 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.
+
+// Flags: --allow-natives-syntax
+
+function baz(x, f) { return x.length; };
+
+function bar(x, y) {
+  if (y) {}
+  baz(x, function() { return x; });
+};
+
+function foo(x) { bar(x, ''); }
+%OptimizeFunctionOnNextCall(foo);
+foo(['a']);