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/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 126b3b9..7ef6955 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -2483,7 +2483,7 @@
     intrinsic_ = intrinsic;
   }
 
-  bool IsInlined() const {
+  bool IsFromInlinedInvoke() const {
     return GetEnvironment()->GetParent() != nullptr;
   }
 
@@ -3603,7 +3603,7 @@
   bool CanThrow() const OVERRIDE {
     // May call runtime and and therefore can throw.
     // TODO: finer grain decision.
-    return !is_referrers_class_;
+    return CanCallRuntime();
   }
 
   ReferenceTypeInfo GetLoadedClassRTI() {
diff --git a/compiler/optimizing/prepare_for_register_allocation.cc b/compiler/optimizing/prepare_for_register_allocation.cc
index a249aa9..ca928ae 100644
--- a/compiler/optimizing/prepare_for_register_allocation.cc
+++ b/compiler/optimizing/prepare_for_register_allocation.cc
@@ -86,16 +86,6 @@
     DCHECK(last_input != nullptr)
         << "Last input is not HLoadClass. It is " << last_input->DebugName();
 
-    // The static call will initialize the class so there's no need for a clinit check if
-    // it's the first user.
-    // There is one special case where we still need the clinit check, when inlining. Because
-    // currently the callee is responsible for reporting parameters to the GC, the code
-    // that walks the stack during `artQuickResolutionTrampoline` cannot be interrupted for GC.
-    // Therefore we cannot allocate any object in that code, including loading a new class.
-    if (last_input == invoke->GetPrevious() && !invoke->IsInlined()) {
-      last_input->SetMustGenerateClinitCheck(false);
-    }
-
     // Remove a load class instruction as last input of a static
     // invoke, which has been added (along with a clinit check,
     // removed by PrepareForRegisterAllocation::VisitClinitCheck
@@ -104,10 +94,20 @@
     // stage (i.e., after inlining has been performed).
     invoke->RemoveLoadClassAsLastInput();
 
-    // If the load class instruction is no longer used, remove it from
-    // the graph.
-    if (!last_input->HasUses() && !(last_input->MustGenerateClinitCheck() && invoke->IsInlined())) {
-      last_input->GetBlock()->RemoveInstruction(last_input);
+    // The static call will initialize the class so there's no need for a clinit check if
+    // it's the first user.
+    // There is one special case where we still need the clinit check, when inlining. Because
+    // currently the callee is responsible for reporting parameters to the GC, the code
+    // that walks the stack during `artQuickResolutionTrampoline` cannot be interrupted for GC.
+    // Therefore we cannot allocate any object in that code, including loading a new class.
+    if (last_input == invoke->GetPrevious() && !invoke->IsFromInlinedInvoke()) {
+      last_input->SetMustGenerateClinitCheck(false);
+
+      // If the load class instruction is no longer used, remove it from
+      // the graph.
+      if (!last_input->HasUses()) {
+        last_input->GetBlock()->RemoveInstruction(last_input);
+      }
     }
   }
 }
diff --git a/test/482-checker-loop-back-edge-use/src/Main.java b/test/482-checker-loop-back-edge-use/src/Main.java
index 5754723..a4280de 100644
--- a/test/482-checker-loop-back-edge-use/src/Main.java
+++ b/test/482-checker-loop-back-edge-use/src/Main.java
@@ -36,8 +36,8 @@
   }
 
   /// CHECK-START: void Main.loop3(boolean) liveness (after)
-  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,62)} uses:[58,62]
-  /// CHECK:         Goto            liveness:60
+  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,64)} uses:[60,64]
+  /// CHECK:         Goto            liveness:62
 
   /// CHECK-START: void Main.loop3(boolean) liveness (after)
   /// CHECK-NOT:     Goto liveness:56
@@ -63,9 +63,9 @@
   }
 
   /// CHECK-START: void Main.loop5(boolean) liveness (after)
-  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,52)} uses:[35,44,48,52]
-  /// CHECK:         Goto            liveness:46
-  /// CHECK:         Goto            liveness:50
+  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,54)} uses:[37,46,50,54]
+  /// CHECK:         Goto            liveness:48
+  /// CHECK:         Goto            liveness:52
   public static void loop5(boolean incoming) {
     // 'incoming' must have a use at both back edges.
     while (Runtime.getRuntime() != null) {
@@ -76,8 +76,8 @@
   }
 
   /// CHECK-START: void Main.loop6(boolean) liveness (after)
-  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,48)} uses:[26,48]
-  /// CHECK:         Goto            liveness:46
+  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,50)} uses:[26,50]
+  /// CHECK:         Goto            liveness:48
 
   /// CHECK-START: void Main.loop6(boolean) liveness (after)
   /// CHECK-NOT:     Goto            liveness:24
@@ -90,9 +90,9 @@
   }
 
   /// CHECK-START: void Main.loop7(boolean) liveness (after)
-  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,52)} uses:[34,43,48,52]
-  /// CHECK:         Goto            liveness:46
-  /// CHECK:         Goto            liveness:50
+  /// CHECK:         ParameterValue  liveness:4  ranges:{[4,54)} uses:[36,45,50,54]
+  /// CHECK:         Goto            liveness:48
+  /// CHECK:         Goto            liveness:52
   public static void loop7(boolean incoming) {
     // 'incoming' must have a use at both back edges.
     while (Runtime.getRuntime() != null) {
@@ -102,9 +102,9 @@
   }
 
   /// CHECK-START: void Main.loop8() liveness (after)
-  /// CHECK:         StaticFieldGet  liveness:14 ranges:{[14,46)} uses:[37,42,46]
-  /// CHECK:         Goto            liveness:40
-  /// CHECK:         Goto            liveness:44
+  /// CHECK:         StaticFieldGet  liveness:14 ranges:{[14,48)} uses:[39,44,48]
+  /// CHECK:         Goto            liveness:42
+  /// CHECK:         Goto            liveness:46
   public static void loop8() {
     // 'incoming' must have a use at both back edges.
     boolean incoming = field;
@@ -114,8 +114,8 @@
   }
 
   /// CHECK-START: void Main.loop9() liveness (after)
-  /// CHECK:         StaticFieldGet  liveness:24 ranges:{[24,38)} uses:[33,38]
-  /// CHECK:         Goto            liveness:40
+  /// CHECK:         StaticFieldGet  liveness:26 ranges:{[26,40)} uses:[35,40]
+  /// CHECK:         Goto            liveness:42
   public static void loop9() {
     while (Runtime.getRuntime() != null) {
       // 'incoming' must only have a use in the inner loop.
diff --git a/test/496-checker-inlinling-and-class-loader/expected.txt b/test/496-checker-inlinling-and-class-loader/expected.txt
new file mode 100644
index 0000000..c6fcb51
--- /dev/null
+++ b/test/496-checker-inlinling-and-class-loader/expected.txt
@@ -0,0 +1,4 @@
+Request for LoadedByMyClassLoader
+Request for Main
+In between the two calls.
+In $noinline$bar
diff --git a/test/496-checker-inlinling-and-class-loader/info.txt b/test/496-checker-inlinling-and-class-loader/info.txt
new file mode 100644
index 0000000..aa4b256
--- /dev/null
+++ b/test/496-checker-inlinling-and-class-loader/info.txt
@@ -0,0 +1,2 @@
+Regression test to ensure compilers preserve JLS
+semantics of class loading.
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 */ }
+  }
+}
diff --git a/test/Android.run-test.mk b/test/Android.run-test.mk
index e95f147..714953c 100644
--- a/test/Android.run-test.mk
+++ b/test/Android.run-test.mk
@@ -382,7 +382,8 @@
 
 # Known broken tests for the default compiler (Quick).
 TEST_ART_BROKEN_DEFAULT_RUN_TESTS := \
-  457-regs
+  457-regs \
+  496-checker-inlining-and-class-loader
 
 ifneq (,$(filter default,$(COMPILER_TYPES)))
   ART_TEST_KNOWN_BROKEN += $(call all-run-test-names,$(TARGET_TYPES),$(RUN_TYPES),$(PREBUILD_TYPES), \