[turbofan] Add bounds check to Node::InputAt(index) and fix tests that go out of bounds.

src/compiler/node.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_NODE_H_
 #define V8_COMPILER_NODE_H_
 
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 #include "src/types-inl.h"
@@ skipping 40 matching lines @@
   void set_op(const Operator* op) { op_ = op; }
 
   IrOpcode::Value opcode() const {
     DCHECK(op_->opcode() <= IrOpcode::kLast);
     return static_cast<IrOpcode::Value>(op_->opcode());
   }
 
   NodeId id() const { return id_; }
 
   int InputCount() const { return input_count(); }
-  Node* InputAt(int index) const { return GetInputRecordPtr(index)->to; }
+  Node* InputAt(int index) const {
+#if DEBUG
+    if (index < 0 || index >= InputCount()) {
+      V8_Fatal(__FILE__, __LINE__, "Node #%d:%s->InputAt(%d) out of bounds",
+               id(), op()->mnemonic(), index);
+    }
+#endif
+    return GetInputRecordPtr(index)->to;
+  }
   inline void ReplaceInput(int index, Node* new_to);
   void AppendInput(Zone* zone, Node* new_to);
   void InsertInput(Zone* zone, int index, Node* new_to);
   void RemoveInput(int index);
   void NullAllInputs();
   void TrimInputCount(int new_input_count);
 
   int UseCount() const;
   void ReplaceUses(Node* replace_to);
 
@@ skipping 404 matching lines @@
 
 void Node::ReplaceInput(int index, Node* new_to) {
   GetInputRecordPtr(index)->Update(new_to);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_NODE_H_