[turbofan] Ensure that NTLs are always properly connected to the end.

src/compiler/js-generic-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/code-stubs.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/js-generic-lowering.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-aux-data-inl.h"
@@ skipping 27 matching lines @@
     case IrOpcode::k##x: \
       Lower##x(node);    \
       break;
     JS_OP_LIST(DECLARE_CASE)
 #undef DECLARE_CASE
     case IrOpcode::kBranch:
       // TODO(mstarzinger): If typing is enabled then simplified lowering will
       // have inserted the correct ChangeBoolToBit, otherwise we need to perform
       // poor-man's representation inference here and insert manual change.
       if (!info()->is_typing_enabled()) {
-        Node* test = graph()->NewNode(machine()->WordEqual(), node->InputAt(0),
-                                      jsgraph()->TrueConstant());
-        node->ReplaceInput(0, test);
+        Node* condition = node->InputAt(0);
+        if (condition->opcode() != IrOpcode::kAlways) {
+          Node* test = graph()->NewNode(machine()->WordEqual(), condition,
+                                        jsgraph()->TrueConstant());
+          node->ReplaceInput(0, test);
+        }
         break;
       }
       // Fall-through.
     default:
       // Nothing to see.
       return NoChange();
   }
   return Changed(node);
 }
 
@@ skipping 370 matching lines @@
 
 
 void JSGenericLowering::LowerJSCallRuntime(Node* node) {
   const CallRuntimeParameters& p = CallRuntimeParametersOf(node->op());
   ReplaceWithRuntimeCall(node, p.id(), static_cast<int>(p.arity()));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8