Fix `String` ctor with `hibyte` for empty strings.

Mark empty strings as compressed for any value of `hibyte`.

Test: New test in 021-string2.
Test: testrunner.py --host --optimizing -t 021-string2
Bug: 250530521
Change-Id: Ie129fba599a24021eda0a4a81a39fd3fc3769597

1 files changed, 6 insertions, 0 deletions

diff --git a/test/021-string2/src/Main.java b/test/021-string2/src/Main.java
index 39595f3280..5da10ca722 100644
--- a/test/021-string2/src/Main.java
+++ b/test/021-string2/src/Main.java
@@ -119,6 +119,7 @@ public class Main {
         testEqualsConstString();
         testConstStringEquals();
         testStringConcat();
+        testEmptyWithHighByte();
 
         // Regression tests for String.setCharAt() breaking string compression invariants.
         Locale en_US = new Locale("en", "US");
@@ -760,6 +761,11 @@ public class Main {
         Assert.assertEquals("abc\u0440xyzw\u0440", "abc\u0440".concat("xyzw\u0440"));
     }
 
+    public static void testEmptyWithHighByte() {
+        String empty = new String(new byte[0], 1);
+        Assert.assertEquals("", empty);
+    }
+
     public static boolean $noinline$equalsConstString0(String s) {
         return s.equals("");
     }