8315131: Clarify VarHandle set/get access on 32-bit platforms

Reviewed-by: rriggs, iris
Backport-of: ea6674fec8702eea481afa7ca7e522cbacd53841

Author: liach

src/java.base/share/classes/java/lang/foreign/MemoryLayout.java

@@ -276,10 +276,10 @@
  * if {@code A >= S}. An aligned var handle is guaranteed to support the following
  * access modes:
  * <ul>
- * <li>read write access modes for all {@code T}. On 32-bit platforms, access modes
- *     {@code get} and {@code set} for {@code long}, {@code double} and {@code MemorySegment}
- *     are supported but might lead to word tearing, as described in Section {@jls 17.7}.
- *     of <cite>The Java Language Specification</cite>.
+ * <li>read write access modes for all {@code T}.  Access modes {@code get} and
+ *     {@code set} for {@code long}, {@code double} and {@code MemorySegment}
+ *     are supported but have no atomicity guarantee, as described in Section
+ *     {@jls 17.7} of <cite>The Java Language Specification</cite>.
  * <li>atomic update access modes for {@code int}, {@code long},
  *     {@code float}, {@code double} and {@link MemorySegment}.
  *     (Future major platform releases of the JDK may support additional

src/java.base/share/classes/java/lang/invoke/MethodHandles.java

@@ -4305,9 +4305,10 @@ public static VarHandle byteArrayViewVarHandle(Class<?> viewArrayClass,
      * If access is aligned then following access modes are supported and are
      * guaranteed to support atomic access:
      * <ul>
-     * <li>read write access modes for all {@code T}, with the exception of
-     *     access modes {@code get} and {@code set} for {@code long} and
-     *     {@code double} on 32-bit platforms.
+     * <li>read write access modes for all {@code T}.  Access modes {@code get}
+     *     and {@code set} for {@code long} and {@code double} are supported but
+     *     have no atomicity guarantee, as described in Section {@jls 17.7} of
+     *     <cite>The Java Language Specification</cite>.
      * <li>atomic update access modes for {@code int}, {@code long},
      *     {@code float} or {@code double}.
      *     (Future major platform releases of the JDK may support additional