classlib: improve and fix Integer/Long long bit operations

classlib/src/main/java/org/teavm/classlib/java/lang/TInteger.java

@@ -331,11 +331,11 @@ public class TInteger extends TNumber implements TComparable<TInteger> {
     }
 
     public static int highestOneBit(int i) {
-        return 0x80000000 >>> numberOfLeadingZeros(i);
+        return i & (0x80000000 >>> numberOfLeadingZeros(i));
     }
 
     public static int lowestOneBit(int i) {
-        return 1 << numberOfTrailingZeros(i);
+        return -i & i;
     }
 
     public static int bitCount(int i) {

classlib/src/main/java/org/teavm/classlib/java/lang/TLong.java

@@ -254,10 +254,6 @@ public class TLong extends TNumber implements TComparable<TLong> {
         }
     }
 
-    public static long highestOneBit(long i) {
-        return 0x8000000000000000L >>> numberOfLeadingZeros(i);
-    }
-
     public static int numberOfLeadingZeros(long i) {
         if (i == 0) {
             return SIZE;
@@ -322,9 +318,12 @@ public class TLong extends TNumber implements TComparable<TLong> {
         return SIZE - n - 1;
     }
 
+    public static long highestOneBit(long i) {
+        return i & (0x8000000000000000L >>> numberOfLeadingZeros(i));
+    }
 
     public static long lowestOneBit(long i) {
-        return 1L << numberOfTrailingZeros(i);
+        return -i & i;
     }
 
     public static int bitCount(long i) {

tests/src/test/java/org/teavm/classlib/java/lang/IntegerTest.java

@@ -26,6 +26,12 @@ import org.teavm.junit.WholeClassCompilation;
 @RunWith(TeaVMTestRunner.class)
 @WholeClassCompilation
 public class IntegerTest {
+    @Test
+    public void testRightUnsignedShift() {
+        assertEquals(1 << 31, Integer.MIN_VALUE >>> Integer.parseInt("0"));
+        assertEquals(-1, -1 >>> Integer.parseInt("0"));
+    }
+
     @Test
     public void parsesInteger() {
         assertEquals(0, Integer.parseInt("0", 10));
@@ -86,6 +92,7 @@ public class IntegerTest {
 
     @Test
     public void numberOfLeadingZerosComputed() {
+        assertEquals(0, Integer.numberOfLeadingZeros(-1));
         assertEquals(1, Integer.numberOfLeadingZeros(0x40000000));
         assertEquals(1, Integer.numberOfLeadingZeros(0x40000123));
         assertEquals(1, Integer.numberOfLeadingZeros(0x7FFFFFFF));
@@ -112,6 +119,21 @@ public class IntegerTest {
         assertEquals(32, Integer.numberOfTrailingZeros(0));
     }
 
+    @Test
+    public void highestOneBit() {
+        assertEquals(1 << 31, Integer.highestOneBit(-1));
+        assertEquals(1 << 31, Integer.highestOneBit(Integer.MIN_VALUE));
+        assertEquals(0, Integer.highestOneBit(0));
+        assertEquals(16, Integer.highestOneBit(31));
+    }
+
+    @Test
+    public void lowestOneBit() {
+        assertEquals(0, Integer.lowestOneBit(0));
+        assertEquals(2, Integer.lowestOneBit(50));
+        assertEquals(1, Integer.lowestOneBit(-1));
+    }
+
     @Test
     public void bitsCounted() {
         assertEquals(0, Integer.bitCount(0));

tests/src/test/java/org/teavm/classlib/java/lang/LongTest.java

@@ -64,6 +64,21 @@ public class LongTest {
         assertEquals(0xF63BA00000000000L, Long.reverse(0x5DC6F));
     }
 
+    @Test
+    public void highestOneBit() {
+        assertEquals(1L << 63, Long.highestOneBit(-1L));
+        assertEquals(1L << 63, Long.highestOneBit(Long.MIN_VALUE));
+        assertEquals(0, Long.highestOneBit(0L));
+        assertEquals(16L, Long.highestOneBit(31L));
+    }
+
+    @Test
+    public void lowestOneBit() {
+        assertEquals(0L, Long.lowestOneBit(0L));
+        assertEquals(2L, Long.lowestOneBit(50L));
+        assertEquals(1L, Long.lowestOneBit(-1L));
+    }
+
     @Test
     public void bitsCounted() {
         assertEquals(39, Long.bitCount(2587208649207147453L));