Change shareElements message to allow sharing a subset.

Author: aardvark179

src/main/java/org/truffleruby/core/array/library/ArrayStoreLibrary.java

@@ -126,8 +126,9 @@ public Object makeShared(Object store) {
         return new SharedArrayStorage(store);
     }
 
-    /** Do any work required to start sharing elements across threads. */
-    public void shareElements(Object store) {
+    /** Do any work required to start sharing elements across threads in the range from {@code start} (inclusive) to
+     * {@code end} (exclusive). */
+    public void shareElements(Object store, int start, int end) {
     }
 
     /** Return a description of {@code store} for debugging output. */

src/main/java/org/truffleruby/core/array/library/DelegatedArrayStorage.java

@@ -64,14 +64,14 @@ public Object backingStore(
     @ExportMessage
     protected Object makeShared(
             @CachedLibrary(limit = "1") ArrayStoreLibrary stores) {
-        stores.shareElements(this);
+        stores.shareElements(this, 0, length);
         return new SharedArrayStorage(this);
     }
 
     @ExportMessage
-    protected void shareElements(
+    protected void shareElements(int start, int end,
             @CachedLibrary(limit = "1") ArrayStoreLibrary stores) {
-        stores.shareElements(storage);
+        stores.shareElements(storage, offset + start, offset + end);
     }
 
     @ExportMessage

src/main/java/org/truffleruby/core/array/library/NativeArrayStorage.java

@@ -145,21 +145,21 @@ protected Object[] boxedCopyOfRange(int start, int length,
     @ExportMessage
     protected static Object makeShared(NativeArrayStorage store,
             @CachedLibrary("store") ArrayStoreLibrary stores) {
-        stores.shareElements(store);
+        stores.shareElements(store, 0, stores.capacity(store));
         return new SharedArrayStorage(store);
     }
 
     @ExportMessage
     static class ShareElements {
 
         @Specialization
-        protected static void shareElements(NativeArrayStorage store,
+        protected static void shareElements(NativeArrayStorage store, int start, int end,
                 @CachedLibrary("store") ArrayStoreLibrary node,
                 @Cached @Exclusive LoopConditionProfile loopProfile,
                 @Cached WriteBarrierNode writeBarrierNode) {
-            int i = 0;
+            int i = start;
             try {
-                for (; loopProfile.inject(i < store.length); i++) {
+                for (; loopProfile.inject(i < end); i++) {
                     writeBarrierNode.executeWriteBarrier(node.read(store, i));
                 }
             } finally {

src/main/java/org/truffleruby/core/array/library/ObjectArrayStore.java

@@ -84,21 +84,21 @@ protected static Object[] boxedCopyOfRange(Object[] store, int start, int length
     @ExportMessage
     protected static Object makeShared(Object[] store,
             @CachedLibrary("store") ArrayStoreLibrary stores) {
-        stores.shareElements(store);
+        stores.shareElements(store, 0, stores.capacity(store));
         return new SharedArrayStorage(store);
     }
 
     @ExportMessage
     static class ShareElements {
 
         @Specialization
-        protected static void shareElements(Object[] store,
+        protected static void shareElements(Object[] store, int start, int end,
                 @CachedLibrary("store") ArrayStoreLibrary node,
                 @Cached @Exclusive LoopConditionProfile loopProfile,
                 @Cached WriteBarrierNode writeBarrierNode) {
-            int i = 0;
+            int i = start;
             try {
-                for (; loopProfile.inject(i < store.length); i++) {
+                for (; loopProfile.inject(i < end); i++) {
                     writeBarrierNode.executeWriteBarrier(store[i]);
                 }
             } finally {