[turbofan] Use Node input iterators where possible

src/compiler/graph-reducer.cc

Index: src/compiler/graph-reducer.cc
diff --git a/src/compiler/graph-reducer.cc b/src/compiler/graph-reducer.cc
index b13b9547140fcc69952abaa7037c8d7fb63cee7b..9f550c9eb8a5418123f80a896e44c44ccb11cfa9 100644
--- a/src/compiler/graph-reducer.cc
+++ b/src/compiler/graph-reducer.cc
@@ -115,15 +115,25 @@ void GraphReducer::ReduceTop() {
 
   // Recurse on an input if necessary.
   int start = entry.input_index < node->InputCount() ? entry.input_index : 0;
-  for (int i = start; i < node->InputCount(); i++) {
-    Node* input = node->InputAt(i);
-    entry.input_index = i + 1;
-    if (input != node && Recurse(input)) return;
+
+  Node::Inputs node_inputs = node->inputs();
+  auto node_inputs_begin = node_inputs.begin();
+  auto node_inputs_end = node_inputs.end();
+  DCHECK(node_inputs_end == node_inputs_begin + node->InputCount());
+
+  for (auto it = node_inputs_begin + start; it != node_inputs_end; ++it) {
+    Node* input = *it;
+    if (input != node && Recurse(input)) {
+      entry.input_index = (it - node_inputs_begin) + 1;
+      return;
+    }
   }
-  for (int i = 0; i < start; i++) {
-    Node* input = node->InputAt(i);
-    entry.input_index = i + 1;
-    if (input != node && Recurse(input)) return;
+  for (auto it = node_inputs_begin; it != node_inputs_begin + start; ++it) {
+    Node* input = *it;
+    if (input != node && Recurse(input)) {
+      entry.input_index = (it - node_inputs_begin) + 1;
+      return;
+    }
   }
 
   // Remember the max node id before reduction.
@@ -139,10 +149,15 @@ void GraphReducer::ReduceTop() {
   Node* const replacement = reduction.replacement();
   if (replacement == node) {
     // In-place update of {node}, may need to recurse on an input.
-    for (int i = 0; i < node->InputCount(); ++i) {
-      Node* input = node->InputAt(i);
-      entry.input_index = i + 1;
-      if (input != node && Recurse(input)) return;
+    Node::Inputs node_inputs = node->inputs();
+    auto node_inputs_begin = node_inputs.begin();
+    auto node_inputs_end = node_inputs.end();
+    for (auto it = node_inputs_begin; it != node_inputs_end; ++it) {
+      Node* input = *it;
+      if (input != node && Recurse(input)) {
+        entry.input_index = (it - node_inputs_begin) + 1;
+        return;
+      }
     }
   }