Ensure object ArraySet with null value does not need a type check.

The art::PrepareForRegisterAllocation visitor can remove an
art::BoundType instruction as value input of an
art::ArraySet instruction, possibly replacing it with an
art::NullConstant.  If this happens, remove the need for a
type check in this art::ArraySet.

Bug: 27638110
Change-Id: I6270f8a8e22822a24d8a5919df427ca9c64d121b

1 files changed, 68 insertions, 0 deletions

diff --git a/test/590-checker-array-set-null-regression/src/Main.java b/test/590-checker-array-set-null-regression/src/Main.java
new file mode 100644
index 0000000000..792ee4ecd6
--- /dev/null
+++ b/test/590-checker-array-set-null-regression/src/Main.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class Main {
+
+  public static void main(String args[]) {
+    Element[] elements = new Element[51];
+    testArraySetCheckCastNull(elements);
+
+    System.out.println("passed");
+  }
+
+  /// CHECK-START: void Main.testArraySetCheckCastNull(Main$Element[]) builder (after)
+  /// CHECK:         <<Array:l\d+>>         ParameterValue
+  /// CHECK-DAG:     <<Index:i\d+>>         IntConstant 42
+  /// CHECK-DAG:     <<Null:l\d+>>          NullConstant
+  /// CHECK-DAG:     <<Class:l\d+>>         LoadClass
+  /// CHECK-DAG:                            CheckCast [<<Null>>,<<Class>>]
+  /// CHECK-DAG:     <<CheckedValue:l\d+>>  BoundType [<<Null>>] klass:Main$Element can_be_null:true
+  /// CHECK-DAG:     <<CheckedArray:l\d+>>  NullCheck [<<Array>>]
+  /// CHECK-DAG:     <<Length:i\d+>>        ArrayLength [<<CheckedArray>>]
+  /// CHECK-DAG:     <<CheckedIndex:i\d+>>  BoundsCheck [<<Index>>,<<Length>>]
+  /// CHECK-DAG:     <<ArraySet:v\d+>>      ArraySet [<<CheckedArray>>,<<CheckedIndex>>,<<CheckedValue>>] needs_type_check:true
+
+  /// CHECK-START: void Main.testArraySetCheckCastNull(Main$Element[]) instruction_simplifier (after)
+  /// CHECK-NOT:                            CheckCast
+
+  /// CHECK-START: void Main.testArraySetCheckCastNull(Main$Element[]) prepare_for_register_allocation (before)
+  /// CHECK:         <<Array:l\d+>>         ParameterValue
+  /// CHECK-DAG:     <<Index:i\d+>>         IntConstant 42
+  /// CHECK-DAG:     <<Null:l\d+>>          NullConstant
+  /// CHECK-DAG:     <<Class:l\d+>>         LoadClass
+  /// CHECK-DAG:     <<CheckedValue:l\d+>>  BoundType [<<Null>>]
+  /// CHECK-DAG:     <<CheckedArray:l\d+>>  NullCheck [<<Array>>]
+  /// CHECK-DAG:     <<Length:i\d+>>        ArrayLength [<<CheckedArray>>]
+  /// CHECK-DAG:     <<CheckedIndex:i\d+>>  BoundsCheck [<<Index>>,<<Length>>]
+  /// CHECK-DAG:     <<ArraySet:v\d+>>      ArraySet [<<CheckedArray>>,<<CheckedIndex>>,<<CheckedValue>>] needs_type_check:true
+
+  /// CHECK-START: void Main.testArraySetCheckCastNull(Main$Element[]) prepare_for_register_allocation (after)
+  /// CHECK:         <<Array:l\d+>>         ParameterValue
+  /// CHECK-DAG:     <<Index:i\d+>>         IntConstant 42
+  /// CHECK-DAG:     <<Null:l\d+>>          NullConstant
+  /// CHECK-DAG:     <<Class:l\d+>>         LoadClass
+  /// CHECK-DAG:     <<Length:i\d+>>        ArrayLength [<<Array>>]
+  /// CHECK-DAG:     <<ArraySet:v\d+>>      ArraySet [<<Array>>,<<Index>>,<<Null>>] needs_type_check:false
+
+  static void testArraySetCheckCastNull(Element[] elements) {
+    Object object = null;
+    Element element = (Element) object;
+    elements[42] = element;
+  }
+
+  class Element {}
+
+}