Make @TruffleBoundary more local.

Author: ppisl

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/list/ListBuiltins.java

@@ -547,18 +547,9 @@ public PNone insertLongIndex(PList list, long index, Object value,
         }
 
         @Specialization
-        @TruffleBoundary
         public PNone insertPIntIndex(PList list, PInt index, Object value,
                         @Cached("createListInsertNode()") ListInsertNode insertNode) {
-            int where = 0;
-            BigInteger bigIndex = index.getValue();
-            if (bigIndex.compareTo(BigInteger.valueOf(Integer.MIN_VALUE)) == -1) {
-                where = 0;
-            } else if (bigIndex.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) == 1) {
-                where = Integer.MAX_VALUE;
-            } else {
-                where = bigIndex.intValue();
-            }
+            int where = normalizePIntForIndex(index);
             where = normalizeIndex(where, list.len());
             return insertNode.execute(list, where, value);
         }
@@ -574,6 +565,20 @@ public PNone insert(PList list, Object i, Object value,
             return insertNode.execute(list, indexValue, value);
         }
 
+        @TruffleBoundary
+        private static int normalizePIntForIndex(PInt index) {
+            int where = 0;
+            BigInteger bigIndex = index.getValue();
+            if (bigIndex.compareTo(BigInteger.valueOf(Integer.MIN_VALUE)) == -1) {
+                where = 0;
+            } else if (bigIndex.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) == 1) {
+                where = Integer.MAX_VALUE;
+            } else {
+                where = bigIndex.intValue();
+            }
+            return where;
+        }
+
         private static int normalizeIndex(int index, int len) {
             int idx = index;
             if (idx < 0) {