dict init: split into 2 specializations with rewrite on unmodifiable storage exception

Author: cosminbasca

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/HashingStorageNodes.java

@@ -300,16 +300,17 @@ public void doPDict(PDict self, PDict iterable, @SuppressWarnings("unused") PKey
             self.setDictStorage(iterable.getDictStorage().copy(HashingStorage.DEFAULT_EQIVALENCE));
         }
 
-        @Specialization(guards = {"!isNoValue(iterable)", "!isEmpty(kwargs)"})
+        @Specialization(guards = {"!isNoValue(iterable)", "!isEmpty(kwargs)"}, rewriteOn = HashingStorage.UnmodifiableStorageException.class)
         public void doPDictKwargs(PDict self, PDict iterable, PKeyword[] kwargs,
-                        @Cached("create()") UnionNode unionNode) {
-            HashingStorage dictStorage;
-            try {
-                dictStorage = iterable.getDictStorage().copy(HashingStorage.DEFAULT_EQIVALENCE);
-                dictStorage.addAll(new KeywordsStorage(kwargs));
-            } catch (HashingStorage.UnmodifiableStorageException e) {
-                dictStorage = unionNode.execute(iterable.getDictStorage(), new KeywordsStorage(kwargs));
-            }
+                                  @Cached("create()") UnionNode unionNode) {
+            HashingStorage dictStorage = unionNode.execute(iterable.getDictStorage(), new KeywordsStorage(kwargs));
+            self.setDictStorage(dictStorage);
+        }
+
+        @Specialization(guards = {"!isNoValue(iterable)", "!isEmpty(kwargs)"})
+        public void doPDictKwargs(PDict self, PDict iterable, PKeyword[] kwargs) {
+            HashingStorage dictStorage = iterable.getDictStorage().copy(HashingStorage.DEFAULT_EQIVALENCE);
+            dictStorage.addAll(new KeywordsStorage(kwargs));
             self.setDictStorage(dictStorage);
         }