src/java.base/share/classes/java/util/Base64.java

@@ -29,10 +29,11 @@
 import java.io.InputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
+import jdk.internal.HotSpotIntrinsicCandidate;
 
 /**
  * This class consists exclusively of static methods for obtaining
  * encoders and decoders for the Base64 encoding scheme. The
  * implementation of this class supports the following types of Base64

@@ -388,29 +389,35 @@
             if (!doPadding)
                 return this;
             return new Encoder(isURL, newline, linemax, false);
         }
 
+        @HotSpotIntrinsicCandidate
+        private void encodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL) {
+            char[] base64 = isURL ? toBase64URL : toBase64;
+            for (int sp0 = sp, dp0 = dp ; sp0 < sl; ) {
+                int bits = (src[sp0++] & 0xff) << 16 |
+                           (src[sp0++] & 0xff) <<  8 |
+                           (src[sp0++] & 0xff);
+                dst[dp0++] = (byte)base64[(bits >>> 18) & 0x3f];
+                dst[dp0++] = (byte)base64[(bits >>> 12) & 0x3f];
+                dst[dp0++] = (byte)base64[(bits >>> 6)  & 0x3f];
+                dst[dp0++] = (byte)base64[bits & 0x3f];
+            }
+        }
+
         private int encode0(byte[] src, int off, int end, byte[] dst) {
             char[] base64 = isURL ? toBase64URL : toBase64;
             int sp = off;
             int slen = (end - off) / 3 * 3;
             int sl = off + slen;
             if (linemax > 0 && slen  > linemax / 4 * 3)
                 slen = linemax / 4 * 3;
             int dp = 0;
             while (sp < sl) {
                 int sl0 = Math.min(sp + slen, sl);
-                for (int sp0 = sp, dp0 = dp ; sp0 < sl0; ) {
-                    int bits = (src[sp0++] & 0xff) << 16 |
-                               (src[sp0++] & 0xff) <<  8 |
-                               (src[sp0++] & 0xff);
-                    dst[dp0++] = (byte)base64[(bits >>> 18) & 0x3f];
-                    dst[dp0++] = (byte)base64[(bits >>> 12) & 0x3f];
-                    dst[dp0++] = (byte)base64[(bits >>> 6)  & 0x3f];
-                    dst[dp0++] = (byte)base64[bits & 0x3f];
-                }
+                encodeBlock(src, sp, sl0, dst, dp, isURL);
                 int dlen = (sl0 - sp) / 3 * 4;
                 dp += dlen;
                 sp = sl0;
                 if (dlen == linemax && sp < end) {
                     for (byte b : newline){