Faster implementation of long and int rotation (#10187)

I picked up the implementation by @cogman from gerrit and added a few
testcases.

Fixes #9563
Co-authored-by: Thomas May <[email protected]>

Author: zbynek

user/super/com/google/gwt/emul/java/lang/Integer.java

@@ -184,24 +184,15 @@ public static int reverseBytes(int i) {
   }
 
   public static int rotateLeft(int i, int distance) {
-    while (distance-- > 0) {
-      i = i << 1 | ((i < 0) ? 1 : 0);
-    }
-    return i;
+    int lowerBits = i >>> (SIZE - distance);
+    int upperBits = i << distance;
+    return upperBits | lowerBits;
   }
 
   public static int rotateRight(int i, int distance) {
-    int ui = i & MAX_VALUE; // avoid sign extension
-    int carry = (i < 0) ? 0x40000000 : 0; // MIN_VALUE rightshifted 1
-    while (distance-- > 0) {
-      int nextcarry = ui & 1;
-      ui = carry | (ui >> 1);
-      carry = (nextcarry == 0) ? 0 : 0x40000000;
-    }
-    if (carry != 0) {
-      ui = ui | MIN_VALUE;
-    }
-    return ui;
+    int upperBits = i << (SIZE - distance);
+    int lowerBits = i >>> distance;
+    return upperBits | lowerBits;
   }
 
   public static int signum(int i) {

user/super/com/google/gwt/emul/java/lang/Long.java

@@ -128,24 +128,15 @@ public static long reverseBytes(long l) {
   }
 
   public static long rotateLeft(long i, int distance) {
-    while (distance-- > 0) {
-      i = i << 1 | ((i < 0) ? 1 : 0);
-    }
-    return i;
+    long lowerBits = i >>> (SIZE - distance);
+    long upperBits = i << distance;
+    return upperBits | lowerBits;
   }
 
   public static long rotateRight(long i, int distance) {
-    long ui = i & MAX_VALUE; // avoid sign extension
-    long carry = (i < 0) ? 0x4000000000000000L : 0; // MIN_VALUE rightshifted 1
-    while (distance-- > 0) {
-      long nextcarry = ui & 1;
-      ui = carry | (ui >> 1);
-      carry = (nextcarry == 0) ? 0 : 0x4000000000000000L;
-    }
-    if (carry != 0) {
-      ui = ui | MIN_VALUE;
-    }
-    return ui;
+    long upperBits = i << (SIZE - distance);
+    long lowerBits = i >>> distance;
+    return upperBits | lowerBits;
   }
 
   public static int signum(long i) {

user/test/com/google/gwt/emultest/java/lang/IntegerTest.java

@@ -234,13 +234,19 @@ public void testRotateLeft() {
     assertEquals(-1, Integer.rotateLeft(-1, 4));
     assertEquals(Integer.MIN_VALUE, Integer.rotateLeft(0x40000000, 1));
     assertEquals(1, Integer.rotateLeft(Integer.MIN_VALUE, 1));
+    assertEquals(Integer.MIN_VALUE, Integer.rotateLeft(Integer.MIN_VALUE, 0));
+    assertEquals(Integer.MIN_VALUE, Integer.rotateLeft(1, -1));
+    assertEquals(-1, Integer.rotateLeft(-1, 1000));
   }
 
   public void testRotateRight() {
     assertEquals(0, Integer.rotateRight(0, 4));
     assertEquals(Integer.MIN_VALUE, Integer.rotateRight(1, 1));
     assertEquals(0x10000000, Integer.rotateRight(1, 4));
     assertEquals(-1, Integer.rotateRight(-1, 4));
+    assertEquals(Integer.MIN_VALUE, Integer.rotateLeft(Integer.MIN_VALUE, 0));
+    assertEquals(1, Integer.rotateRight(Integer.MIN_VALUE, -1));
+    assertEquals(-1, Integer.rotateRight(-1, 1000));
   }
 
   public void testSignum() {

user/test/com/google/gwt/emultest/java/lang/LongTest.java

@@ -224,13 +224,19 @@ public void testRotateLeft() {
     assertEquals(-1, Long.rotateLeft(-1, 4));
     assertEquals(Long.MIN_VALUE, Long.rotateLeft(0x4000000000000000L, 1));
     assertEquals(1, Long.rotateLeft(Long.MIN_VALUE, 1));
+    assertEquals(Long.MIN_VALUE, Long.rotateLeft(Long.MIN_VALUE, 0));
+    assertEquals(Long.MIN_VALUE, Long.rotateLeft(1, -1));
+    assertEquals(-1, Long.rotateLeft(-1, 1000));
   }
 
   public void testRotateRight() {
     assertEquals(0, Long.rotateRight(0, 4));
     assertEquals(Long.MIN_VALUE, Long.rotateRight(1, 1));
     assertEquals(0x1000000000000000L, Long.rotateRight(1, 4));
     assertEquals(-1, Long.rotateRight(-1, 4));
+    assertEquals(Long.MIN_VALUE, Long.rotateRight(Long.MIN_VALUE, 0));
+    assertEquals(1, Long.rotateRight(Long.MIN_VALUE, -1));
+    assertEquals(-1, Long.rotateRight(-1, 1000));
   }
 
   public void testSignum() {