From 310b0f5f15ac9ef8fb7ed0a12ff9ba3e4da17033 Mon Sep 17 00:00:00 2001
From: Nicolas Geoffray <ngeoffray@google.com>
Date: Wed, 24 Jun 2015 12:41:20 +0100
Subject: [PATCH] Fix another case of un-verified dead code.

bug:22042796
https://code.google.com/p/android/issues/detail?id=178008

(cherry picked from commit 1efcc22cd1895c48adccbe49270d8e8583c2b12d)

Change-Id: I5c0d783e842da39cd3dcbb2f18ccf784e797a64f
---
 compiler/optimizing/builder.cc                   |  9 ++++++--
 test/516-dead-move-result/expected.txt           |  0
 test/516-dead-move-result/info.txt               |  3 +++
 test/516-dead-move-result/smali/MoveResult.smali | 25 ++++++++++++++++++++
 test/516-dead-move-result/src/Main.java          | 29 ++++++++++++++++++++++++
 5 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 test/516-dead-move-result/expected.txt
 create mode 100644 test/516-dead-move-result/info.txt
 create mode 100644 test/516-dead-move-result/smali/MoveResult.smali
 create mode 100644 test/516-dead-move-result/src/Main.java

diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index ed3992310..b564aca27 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -2062,8 +2062,13 @@ bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, uint32
     case Instruction::MOVE_RESULT:
     case Instruction::MOVE_RESULT_WIDE:
     case Instruction::MOVE_RESULT_OBJECT:
-      UpdateLocal(instruction.VRegA(), latest_result_);
-      latest_result_ = nullptr;
+      if (latest_result_ == nullptr) {
+        // Only dead code can lead to this situation, where the verifier
+        // does not reject the method.
+      } else {
+        UpdateLocal(instruction.VRegA(), latest_result_);
+        latest_result_ = nullptr;
+      }
       break;
 
     case Instruction::CMP_LONG: {
diff --git a/test/516-dead-move-result/expected.txt b/test/516-dead-move-result/expected.txt
new file mode 100644
index 000000000..e69de29bb
diff --git a/test/516-dead-move-result/info.txt b/test/516-dead-move-result/info.txt
new file mode 100644
index 000000000..49d948903
--- /dev/null
+++ b/test/516-dead-move-result/info.txt
@@ -0,0 +1,3 @@
+Regression test for the graph builder in optimizing,
+where a move-result was bogus, but it passed the verifier
+because it was dead code.
diff --git a/test/516-dead-move-result/smali/MoveResult.smali b/test/516-dead-move-result/smali/MoveResult.smali
new file mode 100644
index 000000000..9650b588e
--- /dev/null
+++ b/test/516-dead-move-result/smali/MoveResult.smali
@@ -0,0 +1,25 @@
+# Copyright (C) 2015 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.
+
+.class public LMoveResult;
+
+.super Ljava/lang/Object;
+
+.method public static method()V
+   .registers 1
+   goto :b1
+   move-result v0
+   :b1
+   return-void
+.end method
diff --git a/test/516-dead-move-result/src/Main.java b/test/516-dead-move-result/src/Main.java
new file mode 100644
index 000000000..90580a846
--- /dev/null
+++ b/test/516-dead-move-result/src/Main.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+import java.lang.reflect.Method;
+
+public class Main {
+  // Workaround for b/18051191.
+  class InnerClass {}
+
+  public static void main(String[] args) throws Exception {
+    Class<?> c = Class.forName("MoveResult");
+    Method m = c.getMethod("method");
+    Object[] arguments = { };
+    m.invoke(null, arguments);
+  }
+}
-- 
2.11.0