Do not replace a live phi with a dead phi.

A dead phi is not properly typed. Therefore, always use the live phi
equivalent instead.

bug:21865466

(cherry picked from commit 4230e1895b915a22363452823b0e51eabe92cb60)

Change-Id: If9a3313fc953c2eb4be85b625676e48112fcb1f6

1 files changed, 35 insertions, 0 deletions

diff --git a/test/520-equivalent-phi/smali/Equivalent.smali b/test/520-equivalent-phi/smali/Equivalent.smali
new file mode 100644
index 0000000..fb4b756
--- /dev/null
+++ b/test/520-equivalent-phi/smali/Equivalent.smali
@@ -0,0 +1,35 @@
+# 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 LEquivalent;
+
+.super Ljava/lang/Object;
+
+.method public static method([I)V
+   .registers 3
+   const/4 v0, 0
+   if-eq p0, v0, :first_if
+   move-object v0, p0
+   :first_if
+   if-eqz v0, :second_if
+   # Having this move-object used to confuse the type propagation
+   # phase of the optimizing compiler: the phase propagates types
+   # based on uses, but a move-object disappears after SSA, leaving
+   # the compiler with a reference equivalent that has no use. So
+   # we would consider the phi equivalent reference of v0, as dead,
+   # even though it is the one that has the correct type.
+   move-object v1, v0
+   :second_if
+   return-void
+.end method