Preserve class loading semantics in optimizing.

We were being too agressive in removing HLoadClass instructions.
A HInvokeStaticOrDirect can only remove it if it's directly before it.

bug: 21711097
Change-Id: Id63502d90e11da60eccfb46daca62e0d5d022119
diff --git a/test/496-checker-inlinling-and-class-loader/src/Main.java b/test/496-checker-inlinling-and-class-loader/src/Main.java
new file mode 100644
index 0000000..f6d0b41
--- /dev/null
+++ b/test/496-checker-inlinling-and-class-loader/src/Main.java
@@ -0,0 +1,125 @@
+/*
+ * 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.Field;
+import java.lang.reflect.Method;
+import java.util.List;
+
+class MyClassLoader extends ClassLoader {
+  MyClassLoader() throws Exception {
+    super(MyClassLoader.class.getClassLoader());
+
+    // Some magic to get access to the pathList field of BaseDexClassLoader.
+    ClassLoader loader = getClass().getClassLoader();
+    Class<?> baseDexClassLoader = loader.getClass().getSuperclass();
+    Field f = baseDexClassLoader.getDeclaredField("pathList");
+    f.setAccessible(true);
+    Object pathList = f.get(loader);
+
+    // Some magic to get access to the dexField field of pathList.
+    f = pathList.getClass().getDeclaredField("dexElements");
+    f.setAccessible(true);
+    dexElements = (Object[]) f.get(pathList);
+    dexFileField = dexElements[0].getClass().getDeclaredField("dexFile");
+    dexFileField.setAccessible(true);
+  }
+
+  Object[] dexElements;
+  Field dexFileField;
+
+  protected Class<?> loadClass(String className, boolean resolve) throws ClassNotFoundException {
+    System.out.println("Request for " + className);
+
+    // We're only going to handle LoadedByMyClassLoader.
+    if (className != "LoadedByMyClassLoader") {
+      return getParent().loadClass(className);
+    }
+
+    // Mimic what DexPathList.findClass is doing.
+    try {
+      for (Object element : dexElements) {
+        Object dex = dexFileField.get(element);
+        Method method = dex.getClass().getDeclaredMethod(
+            "loadClassBinaryName", String.class, ClassLoader.class, List.class);
+
+        if (dex != null) {
+          Class clazz = (Class)method.invoke(dex, className, this, null);
+          if (clazz != null) {
+            return clazz;
+          }
+        }
+      }
+    } catch (Exception e) { /* Ignore */ }
+    return null;
+  }
+}
+
+class LoadedByMyClassLoader {
+  /// CHECK-START: void LoadedByMyClassLoader.bar() inliner (before)
+  /// CHECK:      LoadClass
+  /// CHECK-NEXT: ClinitCheck
+  /// CHECK-NEXT: InvokeStaticOrDirect
+  /// CHECK-NEXT: LoadClass
+  /// CHECK-NEXT: ClinitCheck
+  /// CHECK-NEXT: StaticFieldGet
+  /// CHECK-NEXT: LoadString
+  /// CHECK-NEXT: NullCheck
+  /// CHECK-NEXT: InvokeVirtual
+
+  /// CHECK-START: void LoadedByMyClassLoader.bar() inliner (after)
+  /// CHECK:      LoadClass
+  /// CHECK-NEXT: ClinitCheck
+                /* We inlined Main.$inline$bar */
+  /// CHECK-NEXT: LoadClass
+  /// CHECK-NEXT: ClinitCheck
+  /// CHECK-NEXT: StaticFieldGet
+  /// CHECK-NEXT: LoadString
+  /// CHECK-NEXT: NullCheck
+  /// CHECK-NEXT: InvokeVirtual
+
+  /// CHECK-START: void LoadedByMyClassLoader.bar() register (before)
+                /* Load and initialize Main */
+  /// CHECK:      LoadClass gen_clinit_check:true
+                /* Load and initialize System */
+  /// CHECK-NEXT: LoadClass gen_clinit_check:true
+  /// CHECK-NEXT: StaticFieldGet
+  /// CHECK-NEXT: LoadString
+  /// CHECK-NEXT: NullCheck
+  /// CHECK-NEXT: InvokeVirtual
+  public static void bar() {
+    Main.$inline$bar();
+    System.out.println("In between the two calls.");
+    Main.$noinline$bar();
+  }
+}
+
+class Main {
+  public static void main(String[] args) throws Exception {
+    MyClassLoader o = new MyClassLoader();
+    Class foo = o.loadClass("LoadedByMyClassLoader");
+    Method m = foo.getDeclaredMethod("bar");
+    m.invoke(null);
+  }
+
+  public static void $inline$bar() {
+  }
+
+  public static void $noinline$bar() {
+    try {
+      System.out.println("In $noinline$bar");
+    } catch (Throwable t) { /* Ignore */ }
+  }
+}