Update the remaining input index of phis after deleting an input.

bug:20715803
bug:20690906

(cherry picked from commit 5d7b7f81ed5455893f984752c00571ef27cc97c5)

Change-Id: Ie55739601b8d6fedc830d6e19d8a053392047d34

3 files changed, 61 insertions, 0 deletions

diff --git a/test/483-dce-block/expected.txt b/test/483-dce-block/expected.txt
new file mode 100644
index 0000000..ef48625
--- /dev/null
+++ b/test/483-dce-block/expected.txt
@@ -0,0 +1 @@
+class Main
diff --git a/test/483-dce-block/info.txt b/test/483-dce-block/info.txt
new file mode 100644
index 0000000..3db88ab
--- /dev/null
+++ b/test/483-dce-block/info.txt
@@ -0,0 +1,2 @@
+Regression test for optimizing that used to crash
+compiling the `foo` method.
diff --git a/test/483-dce-block/src/Main.java b/test/483-dce-block/src/Main.java
new file mode 100644
index 0000000..2f66a74
--- /dev/null
+++ b/test/483-dce-block/src/Main.java
@@ -0,0 +1,58 @@
+/*
+ * 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.
+ */
+
+public class Main {
+  public static void foo(Object o, int a) {
+    Object result = null;
+    if (o instanceof Main) {
+      // The compiler optimizes the type of `o` by introducing
+      // a `HBoundType` in this block.
+      while (a != 3) {
+        if (a == 2) {
+          a++;
+          result = o;
+          continue;
+        } else if (willInline()) {
+          // This block will be detected as dead after inlining.
+          result = new Object();
+          continue;
+        }
+        result = new Object();
+      }
+      // The compiler produces a phi at the back edge for `result`.
+      // Before dead block elimination, the phi has three inputs:
+      // result = (new Object(), new Object(), HBoundType)
+      //
+      // After dead block elimination, the phi has now two inputs:
+      // result = (new Object(), HBoundType)
+      //
+      // Our internal data structure for linking users and inputs expect
+      // the input index stored in that data structure to be the index
+      // in the inputs array. So the index before dead block elimination
+      // of the `HBoundType` would be 2. Dead block elimination must update
+      // that index to be 1.
+    }
+    System.out.println(result.getClass());
+  }
+
+  public static boolean willInline() {
+    return false;
+  }
+
+  public static void main(String[] args) {
+    foo(new Main(), 2);
+  }
+}