Fix loop optimization in the presence of environment uses.

We should not remove instructions that have deoptimize as
users, or that have environment uses in a debuggable setup.

bug: 62536525
bug: 33775412
Test: 656-loop-deopt
Change-Id: Iaec1a0b6e90c6a0169f18c6985f00fd8baf2dece

1 files changed, 104 insertions, 0 deletions

diff --git a/test/656-loop-deopt/src/Main.java b/test/656-loop-deopt/src/Main.java
new file mode 100644
index 0000000000..c99cccf4f1
--- /dev/null
+++ b/test/656-loop-deopt/src/Main.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2017 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) throws Exception {
+    System.loadLibrary(args[0]);
+
+    $noinline$intUpdate(new Main());
+    ensureJitCompiled(Main.class, "$noinline$intUpdate");
+    $noinline$intUpdate(new SubMain());
+    if (myIntStatic != 5000) {
+      throw new Error("Expected 5000, got " + myIntStatic);
+    }
+
+    $noinline$objectUpdate(new Main());
+    ensureJitCompiled(Main.class, "$noinline$objectUpdate");
+    $noinline$objectUpdate(new SubMain());
+
+    $noinline$loopIncrement(new Main());
+    ensureJitCompiled(Main.class, "$noinline$loopIncrement");
+    $noinline$loopIncrement(new SubMain());
+  }
+
+  public boolean doCheck() {
+    return false;
+  }
+
+  public static void $noinline$intUpdate(Main m) {
+    int a = 0;
+    // We used to kill 'a' when the inline cache of 'doCheck' only
+    // contains 'Main' (which makes the only branch using 'a' dead).
+    // So the deoptimization at the inline cache was incorrectly assuming
+    // 'a' was dead.
+    for (int i = 0; i < 5000; i++) {
+      if (m.doCheck()) {
+        a++;
+        // We make this branch the only true user of the 'a' phi. All other uses
+        // of 'a' are phi updates.
+        myIntStatic = a;
+      } else if (myIntStatic == 42) {
+        a = 1;
+      }
+    }
+  }
+
+  public static void $noinline$objectUpdate(Main m) {
+    Object o = new Object();
+    // We used to kill 'o' when the inline cache of 'doCheck' only
+    // contains 'Main' (which makes the only branch using 'a' dead).
+    // So the deoptimization at the inline cache was incorrectly assuming
+    // 'o' was dead.
+    // This lead to a NPE on the 'toString' call just after deoptimizing.
+    for (int i = 0; i < 5000; i++) {
+      if (m.doCheck()) {
+        // We make this branch the only true user of the 'o' phi. All other uses
+        // of 'o' are phi updates.
+        o.toString();
+      } else if (myIntStatic == 42) {
+        o = m;
+      }
+    }
+  }
+
+  public static void $noinline$loopIncrement(Main m) {
+    int k = 0;
+    // We used to kill 'k' and replace it with 5000 when the inline cache
+    // of 'doCheck' only contains 'Main'.
+    // So the deoptimization at the inline cache was incorrectly assuming
+    // 'k' was 5000.
+    for (int i = 0; i < 5000; i++, k++) {
+      if (m.doCheck()) {
+        // We make this branch the only true user of the 'a' phi. All other uses
+        // of 'a' are phi updates.
+        myIntStatic = k;
+      }
+    }
+    if (k != 5000) {
+      throw new Error("Expected 5000, got " + k);
+    }
+  }
+
+  public static int myIntStatic = 0;
+
+  public static native void ensureJitCompiled(Class<?> itf, String name);
+}
+
+class SubMain extends Main {
+  public boolean doCheck() {
+    return true;
+  }
+}