8294278: ForkJoinPool.getAndAddPoolIds should use Unsafe.staticFieldBase

Reviewed-by: burban, chegar, martin

Author: Alan Bateman

src/java.base/share/classes/java/lang/Thread.java

@@ -25,6 +25,7 @@
 
 package java.lang;
 
+import java.lang.reflect.Field;
 import java.security.AccessController;
 import java.security.AccessControlContext;
 import java.security.Permission;
@@ -1107,14 +1108,21 @@ protected Object clone() throws CloneNotSupportedException {
      */
     private static class ThreadNumbering {
         private static final Unsafe U;
-        private static final long NEXT;
+        private static final Object NEXT_BASE;
+        private static final long NEXT_OFFSET;
         static {
             U = Unsafe.getUnsafe();
-            NEXT = U.objectFieldOffset(ThreadNumbering.class, "next");
+            try {
+                Field nextField = ThreadNumbering.class.getDeclaredField("next");
+                NEXT_BASE = U.staticFieldBase(nextField);
+                NEXT_OFFSET = U.staticFieldOffset(nextField);
+            } catch (NoSuchFieldException e) {
+                throw new ExceptionInInitializerError(e);
+            }
         }
         private static volatile int next;
         static int next() {
-            return U.getAndAddInt(ThreadNumbering.class, NEXT, 1);
+            return U.getAndAddInt(NEXT_BASE, NEXT_OFFSET, 1);
         }
     }
 

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java

@@ -36,6 +36,7 @@
 package java.util.concurrent;
 
 import java.lang.Thread.UncaughtExceptionHandler;
+import java.lang.reflect.Field;
 import java.security.AccessController;
 import java.security.AccessControlContext;
 import java.security.Permission;
@@ -1527,6 +1528,7 @@ final void setClearThreadLocals() {
     private static final long RUNSTATE;
     private static final long PARALLELISM;
     private static final long THREADIDS;
+    private static final Object POOLIDS_BASE;
     private static final long POOLIDS;
 
     private boolean compareAndSetCtl(long c, long v) {
@@ -1545,7 +1547,7 @@ private long incrementThreadIds() {
         return U.getAndAddLong(this, THREADIDS, 1L);
     }
     private static int getAndAddPoolIds(int x) {
-        return U.getAndAddInt(ForkJoinPool.class, POOLIDS, x);
+        return U.getAndAddInt(POOLIDS_BASE, POOLIDS, x);
     }
     private int getAndSetParallelism(int v) {
         return U.getAndSetInt(this, PARALLELISM, v);
@@ -3763,7 +3765,9 @@ protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
         U = Unsafe.getUnsafe();
         Class<ForkJoinPool> klass = ForkJoinPool.class;
         try {
-            POOLIDS = U.staticFieldOffset(klass.getDeclaredField("poolIds"));
+            Field poolIdsField = klass.getDeclaredField("poolIds");
+            POOLIDS_BASE = U.staticFieldBase(poolIdsField);
+            POOLIDS = U.staticFieldOffset(poolIdsField);
         } catch (NoSuchFieldException e) {
             throw new ExceptionInInitializerError(e);
         }