From aeee909ea7a5c12c591301e346a1da12c6e356f6 Mon Sep 17 00:00:00 2001
From: Timothy Hoffman <4001421+tim-hoffman@users.noreply.github.com>
Date: Fri, 16 Jul 2021 13:29:45 -0500
Subject: [PATCH] Replace array copy loop with System.arraycopy

---
 src/main/javassist/bytecode/StackMapTable.java     | 12 +++++++++---
 src/main/javassist/bytecode/stackmap/MapMaker.java |  3 +--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/main/javassist/bytecode/StackMapTable.java b/src/main/javassist/bytecode/StackMapTable.java
index 62a6aca0..4fed2010 100644
--- a/src/main/javassist/bytecode/StackMapTable.java
+++ b/src/main/javassist/bytecode/StackMapTable.java
@@ -912,9 +912,15 @@ public class StackMapTable extends AttributeInfo {
         static byte[] insertGap(byte[] info, int where, int gap) {
             int len = info.length;
             byte[] newinfo = new byte[len + gap];
-            for (int i = 0; i < len; i++)
-                newinfo[i + (i < where ? 0 : gap)] = info[i];
-
+            if (where <= 0) {
+                System.arraycopy(info, 0, newinfo, gap, len);
+            } else if (where >= len) {
+                System.arraycopy(info, 0, newinfo, 0, len);
+            } else {
+                assert (where > 0 && where < len);
+                System.arraycopy(info, 0, newinfo, 0, where);
+                System.arraycopy(info, where, newinfo, where + gap, len - where);
+            }
             return newinfo;
         }
 
diff --git a/src/main/javassist/bytecode/stackmap/MapMaker.java b/src/main/javassist/bytecode/stackmap/MapMaker.java
index bd79377f..d016a3be 100644
--- a/src/main/javassist/bytecode/stackmap/MapMaker.java
+++ b/src/main/javassist/bytecode/stackmap/MapMaker.java
@@ -309,8 +309,7 @@ public class MapMaker extends Tracer {
     }
 
     protected static void copyTypeData(int n, TypeData[] srcTypes, TypeData[] destTypes) {
-        for (int i = 0; i < n; i++)
-            destTypes[i] = srcTypes[i];
+        System.arraycopy(srcTypes, 0, destTypes, 0, n);
     }
 
     private static TypeData validateTypeData(TypeData[] data, int length, int index) {
-- 
2.39.5