| // Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| package com.android.tools.r8.ir.analysis; |
| |
| import com.android.tools.r8.errors.Unreachable; |
| import com.android.tools.r8.graph.AppView; |
| import com.android.tools.r8.graph.DexClass; |
| import com.android.tools.r8.graph.DexDefinition; |
| import com.android.tools.r8.graph.DexEncodedField; |
| import com.android.tools.r8.graph.DexEncodedMethod; |
| import com.android.tools.r8.graph.DexItemFactory; |
| import com.android.tools.r8.graph.DexMethod; |
| import com.android.tools.r8.graph.DexType; |
| import com.android.tools.r8.graph.ResolutionResult; |
| import com.android.tools.r8.ir.analysis.type.TypeElement; |
| import com.android.tools.r8.ir.code.BasicBlock; |
| import com.android.tools.r8.ir.code.CatchHandlers.CatchHandler; |
| import com.android.tools.r8.ir.code.DominatorTree; |
| import com.android.tools.r8.ir.code.DominatorTree.Assumption; |
| import com.android.tools.r8.ir.code.DominatorTree.Inclusive; |
| import com.android.tools.r8.ir.code.FieldInstruction; |
| import com.android.tools.r8.ir.code.IRCode; |
| import com.android.tools.r8.ir.code.InitClass; |
| import com.android.tools.r8.ir.code.InstanceGet; |
| import com.android.tools.r8.ir.code.InstancePut; |
| import com.android.tools.r8.ir.code.Instruction; |
| import com.android.tools.r8.ir.code.InstructionIterator; |
| import com.android.tools.r8.ir.code.InvokeDirect; |
| import com.android.tools.r8.ir.code.InvokeInterface; |
| import com.android.tools.r8.ir.code.InvokeStatic; |
| import com.android.tools.r8.ir.code.InvokeSuper; |
| import com.android.tools.r8.ir.code.InvokeVirtual; |
| import com.android.tools.r8.ir.code.NewInstance; |
| import com.android.tools.r8.ir.code.StaticGet; |
| import com.android.tools.r8.ir.code.StaticPut; |
| import com.android.tools.r8.ir.code.Value; |
| import com.android.tools.r8.shaking.AppInfoWithLiveness; |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.Sets; |
| import com.google.common.collect.Streams; |
| import java.util.ArrayDeque; |
| import java.util.BitSet; |
| import java.util.Deque; |
| import java.util.List; |
| import java.util.Set; |
| |
| /** |
| * Analysis that given an instruction determines if a given type is guaranteed to be class |
| * initialized prior the given instruction. |
| */ |
| public class ClassInitializationAnalysis { |
| |
| public enum AnalysisAssumption { |
| INSTRUCTION_DOES_NOT_THROW, |
| NONE |
| } |
| |
| public enum Query { |
| DIRECTLY, |
| DIRECTLY_OR_INDIRECTLY |
| } |
| |
| private static final ClassInitializationAnalysis TRIVIAL = |
| new ClassInitializationAnalysis() { |
| |
| @Override |
| public boolean isClassDefinitelyLoadedBeforeInstruction( |
| DexType type, Instruction instruction) { |
| return false; |
| } |
| }; |
| |
| private final AppView<AppInfoWithLiveness> appView; |
| private final IRCode code; |
| private final DexItemFactory dexItemFactory; |
| |
| private DominatorTree dominatorTree = null; |
| private int markingColor = -1; |
| |
| private ClassInitializationAnalysis() { |
| this.appView = null; |
| this.code = null; |
| this.dexItemFactory = null; |
| } |
| |
| public ClassInitializationAnalysis(AppView<AppInfoWithLiveness> appView, IRCode code) { |
| this.appView = appView; |
| this.code = code; |
| this.dexItemFactory = appView.dexItemFactory(); |
| } |
| |
| // Returns a trivial, conservative analysis that always returns false. |
| public static ClassInitializationAnalysis trivial() { |
| return TRIVIAL; |
| } |
| |
| public boolean isClassDefinitelyLoadedBeforeInstruction(DexType type, Instruction instruction) { |
| DexType context = code.method.holder(); |
| BasicBlock block = instruction.getBlock(); |
| |
| // Visit the instructions in `block` prior to `instruction`. |
| for (Instruction previous : block.getInstructions()) { |
| if (previous == instruction) { |
| break; |
| } |
| if (previous.definitelyTriggersClassInitialization( |
| type, |
| context, |
| appView, |
| Query.DIRECTLY_OR_INDIRECTLY, |
| // The given instruction is only reached if none of the instructions in the same |
| // basic block throws, so we can safely assume that they will not. |
| AnalysisAssumption.INSTRUCTION_DOES_NOT_THROW)) { |
| return true; |
| } |
| } |
| |
| if (dominatorTree == null) { |
| dominatorTree = new DominatorTree(code, Assumption.MAY_HAVE_UNREACHABLE_BLOCKS); |
| } |
| |
| // Visit all the instructions in all the blocks that dominate `block`. |
| for (BasicBlock dominator : dominatorTree.dominatorBlocks(block, Inclusive.NO)) { |
| AnalysisAssumption assumption = getAssumptionForDominator(dominator, block); |
| InstructionIterator instructionIterator = dominator.iterator(); |
| while (instructionIterator.hasNext()) { |
| Instruction previous = instructionIterator.next(); |
| if (previous.definitelyTriggersClassInitialization( |
| type, context, appView, Query.DIRECTLY_OR_INDIRECTLY, assumption)) { |
| return true; |
| } |
| if (dominator.hasCatchHandlers() && previous.instructionTypeCanThrow()) { |
| // All of the instructions that follow the first instruction that may throw are |
| // guaranteed to be non-throwing. Hence they cannot cause any class initializations. |
| assert Streams.stream(instructionIterator) |
| .noneMatch(Instruction::instructionTypeCanThrow); |
| break; |
| } |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * Returns the analysis assumption to use when analyzing the instructions in the given dominator |
| * block. |
| * |
| * <p>If the given block has no catch handlers, then we can safely assume that the instruction |
| * does not throw, because execution would otherwise exit the method. |
| * |
| * <p>As a simple example, consider the method below. In order for the execution to get from the |
| * call to A.foo() to the call to A.bar() the call A.foo() must not throw. |
| * |
| * <pre> |
| * public static void method() { |
| * A.foo(); |
| * A.bar(); |
| * } |
| * </pre> |
| * |
| * This assumption cannot be made in the presence of intraprocedural exceptional control flow. |
| * Consider the following example. |
| * |
| * <pre> |
| * public static void method(A instance) { |
| * try { |
| * instance.field = 42; |
| * } catch (Exception e) { |
| * A.foo(); |
| * return; |
| * } |
| * A.bar(); |
| * } |
| * </pre> |
| * |
| * <p>At the call to A.foo() it is not guaranteed that the class A has been initialized, since |
| * `instance` could always be null. |
| * |
| * <p>At the call to A.bar() it is guaranteed, since the instance field assignment succeeded. |
| */ |
| private AnalysisAssumption getAssumptionForDominator(BasicBlock dominator, BasicBlock block) { |
| if (!dominator.hasCatchHandlers()) { |
| return AnalysisAssumption.INSTRUCTION_DOES_NOT_THROW; |
| } |
| |
| Instruction exceptionalExit = dominator.exceptionalExit(); |
| if (exceptionalExit == null) { |
| // The block cannot throw after all. |
| return AnalysisAssumption.INSTRUCTION_DOES_NOT_THROW; |
| } |
| |
| if (markingColor < 0) { |
| markingColor = code.reserveMarkingColor(); |
| code.markTransitivePredecessors(block, markingColor); |
| } |
| |
| for (CatchHandler<BasicBlock> catchHandler : dominator.getCatchHandlers()) { |
| if (catchHandler.target.isMarked(markingColor)) { |
| // There is a path from this catch handler to the instruction of interest, so we can't make |
| // any assumptions. |
| return AnalysisAssumption.NONE; |
| } |
| } |
| |
| // There are no paths from any of the catch handlers to the instruction of interest, so we can |
| // assume that no instructions in the given block will throw (otherwise, the instruction of |
| // interest will not be reached). |
| return AnalysisAssumption.INSTRUCTION_DOES_NOT_THROW; |
| } |
| |
| /** |
| * The analysis reuses the dominator tree and basic block markings. If the underlying structure of |
| * the IR changes, then this method must be called to reset the dominator tree, return the current |
| * marking color, and clear all marks. |
| */ |
| public void notifyCodeHasChanged() { |
| dominatorTree = null; |
| returnMarkingColor(); |
| } |
| |
| /** Returns the marking color, if any, and clears all marks. */ |
| public void finish() { |
| returnMarkingColor(); |
| } |
| |
| private void returnMarkingColor() { |
| if (markingColor >= 0) { |
| code.returnMarkingColor(markingColor); |
| markingColor = -1; |
| } |
| } |
| |
| public static class InstructionUtils { |
| |
| public static boolean forInitClass( |
| InitClass instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| // Class initialization may fail with ExceptionInInitializerError. |
| return false; |
| } |
| DexClass clazz = appView.definitionFor(instruction.getClassValue()); |
| return clazz != null && isTypeInitializedBy(instruction, type, clazz, appView, mode); |
| } |
| |
| public static boolean forInstanceGet( |
| InstanceGet instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| return forInstanceGetOrPut(instruction, type, appView, mode, assumption); |
| } |
| |
| public static boolean forInstancePut( |
| InstancePut instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| return forInstanceGetOrPut(instruction, type, appView, mode, assumption); |
| } |
| |
| private static boolean forInstanceGetOrPut( |
| FieldInstruction instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| assert instruction.isInstanceGet() || instruction.isInstancePut(); |
| if (assumption == AnalysisAssumption.NONE) { |
| Value object = |
| instruction.isInstanceGet() |
| ? instruction.asInstanceGet().object() |
| : instruction.asInstancePut().object(); |
| if (object.getType().isNullable()) { |
| // If the receiver is null we cannot be sure that the holder has been initialized. |
| return false; |
| } |
| } |
| DexEncodedField field = appView.appInfo().resolveField(instruction.getField()); |
| return field != null && isTypeInitializedBy(instruction, type, field, appView, mode); |
| } |
| |
| public static boolean forInvokeDirect( |
| InvokeDirect instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| if (instruction.getReceiver().getType().isNullable()) { |
| // If the receiver is null we cannot be sure that the holder has been initialized. |
| return false; |
| } |
| } |
| DexEncodedMethod method = appView.definitionFor(instruction.getInvokedMethod()); |
| return method != null && isTypeInitializedBy(instruction, type, method, appView, mode); |
| } |
| |
| public static boolean forInvokeInterface( |
| InvokeInterface instruction, |
| DexType type, |
| DexType context, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| if (instruction.getReceiver().getType().isNullable()) { |
| // If the receiver is null we cannot be sure that the holder has been initialized. |
| return false; |
| } |
| } |
| if (mode == Query.DIRECTLY) { |
| // We cannot ensure exactly which class is being loaded because it depends on the runtime |
| // type of the receiver. |
| // TODO(christofferqa): We can do better if there is a unique target. |
| return false; |
| } |
| if (appView.appInfo().hasLiveness()) { |
| DexEncodedMethod singleTarget = |
| instruction.lookupSingleTarget(appView.withLiveness(), context); |
| if (singleTarget != null) { |
| return isTypeInitializedBy(instruction, type, singleTarget, appView, mode); |
| } |
| } |
| DexMethod method = instruction.getInvokedMethod(); |
| ResolutionResult resolutionResult = |
| appView.appInfo().resolveMethodOnInterface(method.holder, method); |
| if (!resolutionResult.isSingleResolution()) { |
| return false; |
| } |
| DexType holder = resolutionResult.getSingleTarget().holder(); |
| return appView.isSubtype(holder, type).isTrue(); |
| } |
| |
| public static boolean forInvokeStatic( |
| InvokeStatic instruction, |
| DexType type, |
| DexType context, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| // Class initialization may fail with ExceptionInInitializerError. |
| return false; |
| } |
| DexEncodedMethod method = instruction.lookupSingleTarget(appView, context); |
| return method != null && isTypeInitializedBy(instruction, type, method, appView, mode); |
| } |
| |
| public static boolean forInvokeSuper( |
| InvokeSuper instruction, |
| DexType type, |
| DexType context, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| if (instruction.getReceiver().getType().isNullable()) { |
| // If the receiver is null we cannot be sure that the holder has been initialized. |
| return false; |
| } |
| } |
| if (mode == Query.DIRECTLY) { |
| // We cannot ensure exactly which class is being loaded because it depends on the runtime |
| // type of the receiver. |
| // TODO(christofferqa): We can do better if there is a unique target. |
| return false; |
| } |
| if (appView.appInfo().hasLiveness()) { |
| DexEncodedMethod singleTarget = |
| instruction.lookupSingleTarget(appView.withLiveness(), context); |
| if (singleTarget != null) { |
| return isTypeInitializedBy(instruction, type, singleTarget, appView, mode); |
| } |
| } |
| DexMethod method = instruction.getInvokedMethod(); |
| DexClass enclosingClass = appView.definitionFor(method.holder); |
| if (enclosingClass == null) { |
| return false; |
| } |
| DexType superType = enclosingClass.superType; |
| if (superType == null) { |
| return false; |
| } |
| ResolutionResult resolutionResult = |
| appView.appInfo().resolveMethod(superType, method, instruction.itf); |
| if (!resolutionResult.isSingleResolution()) { |
| return false; |
| } |
| DexType holder = resolutionResult.getSingleTarget().holder(); |
| return appView.isSubtype(holder, type).isTrue(); |
| } |
| |
| public static boolean forInvokeVirtual( |
| InvokeVirtual instruction, |
| DexType type, |
| DexType context, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| if (instruction.getReceiver().getType().isNullable()) { |
| // If the receiver is null we cannot be sure that the holder has been initialized. |
| return false; |
| } |
| } |
| if (mode == Query.DIRECTLY) { |
| // We cannot ensure exactly which class is being loaded because it depends on the runtime |
| // type of the receiver. |
| // TODO(christofferqa): We can do better if there is a unique target. |
| return false; |
| } |
| if (appView.appInfo().hasLiveness()) { |
| DexEncodedMethod singleTarget = |
| instruction.lookupSingleTarget(appView.withLiveness(), context); |
| if (singleTarget != null) { |
| return isTypeInitializedBy(instruction, type, singleTarget, appView, mode); |
| } |
| } |
| DexMethod method = instruction.getInvokedMethod(); |
| ResolutionResult resolutionResult = |
| appView.appInfo().resolveMethodOnClass(method.holder, method); |
| if (!resolutionResult.isSingleResolution()) { |
| return false; |
| } |
| DexType holder = resolutionResult.getSingleTarget().holder(); |
| return appView.isSubtype(holder, type).isTrue(); |
| } |
| |
| public static boolean forNewInstance( |
| NewInstance instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| if (assumption == AnalysisAssumption.NONE) { |
| // Instruction may throw. |
| return false; |
| } |
| DexClass clazz = appView.definitionFor(instruction.clazz); |
| return clazz != null && isTypeInitializedBy(instruction, type, clazz, appView, mode); |
| } |
| |
| public static boolean forStaticGet( |
| StaticGet instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| return forStaticGetOrPut(instruction, type, appView, mode, assumption); |
| } |
| |
| public static boolean forStaticPut( |
| StaticPut instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| return forStaticGetOrPut(instruction, type, appView, mode, assumption); |
| } |
| |
| private static boolean forStaticGetOrPut( |
| FieldInstruction instruction, |
| DexType type, |
| AppView<?> appView, |
| Query mode, |
| AnalysisAssumption assumption) { |
| assert instruction.isStaticGet() || instruction.isStaticPut(); |
| if (assumption == AnalysisAssumption.NONE) { |
| // Class initialization may fail with ExceptionInInitializerError. |
| return false; |
| } |
| DexEncodedField field = appView.appInfo().resolveField(instruction.getField()); |
| return field != null && isTypeInitializedBy(instruction, type, field, appView, mode); |
| } |
| |
| private static boolean isTypeInitializedBy( |
| Instruction instruction, |
| DexType typeToBeInitialized, |
| DexDefinition definition, |
| AppView<?> appView, |
| Query mode) { |
| if (mode == Query.DIRECTLY) { |
| if (definition.isDexClass()) { |
| return definition.asDexClass().type == typeToBeInitialized; |
| } |
| if (definition.isDexEncodedMember()) { |
| return definition.asDexEncodedMember().toReference().holder == typeToBeInitialized; |
| } |
| throw new Unreachable(); |
| } |
| |
| Set<DexType> visited = Sets.newIdentityHashSet(); |
| Deque<DexType> worklist = new ArrayDeque<>(); |
| |
| if (definition.isDexClass()) { |
| DexClass clazz = definition.asDexClass(); |
| enqueue(clazz.type, visited, worklist); |
| } else if (definition.isDexEncodedField()) { |
| DexEncodedField field = definition.asDexEncodedField(); |
| enqueue(field.holder(), visited, worklist); |
| } else if (definition.isDexEncodedMethod()) { |
| assert instruction.isInvokeMethod(); |
| DexEncodedMethod method = definition.asDexEncodedMethod(); |
| enqueue(method.holder(), visited, worklist); |
| enqueueInitializedClassesOnNormalExit(method, instruction.inValues(), visited, worklist); |
| } else { |
| assert false; |
| } |
| |
| while (!worklist.isEmpty()) { |
| DexType typeKnownToBeInitialized = worklist.removeFirst(); |
| assert visited.contains(typeKnownToBeInitialized); |
| |
| if (appView.isSubtype(typeKnownToBeInitialized, typeToBeInitialized).isTrue()) { |
| return true; |
| } |
| |
| DexClass clazz = appView.definitionFor(typeKnownToBeInitialized); |
| if (clazz != null) { |
| DexEncodedMethod classInitializer = clazz.getClassInitializer(); |
| if (classInitializer != null) { |
| enqueueInitializedClassesOnNormalExit( |
| classInitializer, ImmutableList.of(), visited, worklist); |
| } |
| } |
| } |
| |
| return false; |
| } |
| |
| private static void enqueue(DexType type, Set<DexType> visited, Deque<DexType> worklist) { |
| if (type.isClassType() && visited.add(type)) { |
| worklist.add(type); |
| } |
| } |
| |
| private static void enqueueInitializedClassesOnNormalExit( |
| DexEncodedMethod method, |
| List<Value> arguments, |
| Set<DexType> visited, |
| Deque<DexType> worklist) { |
| for (DexType type : method.getOptimizationInfo().getInitializedClassesOnNormalExit()) { |
| enqueue(type, visited, worklist); |
| } |
| // If an invoke to an instance method succeeds, then the receiver must be non-null, which |
| // implies that the type of the receiver must be initialized. |
| if (!method.isStatic()) { |
| assert arguments.size() > 0; |
| TypeElement type = arguments.get(0).getType(); |
| if (type.isClassType()) { |
| enqueue(type.asClassType().getClassType(), visited, worklist); |
| } |
| } |
| // If an invoke to a method succeeds, and the method would have thrown and exception if the |
| // i'th argument was null, then the i'th argument must be non-null, which implies that the |
| // type of the i'th argument must be initialized. |
| BitSet nonNullParamOrThrowFacts = method.getOptimizationInfo().getNonNullParamOrThrow(); |
| if (nonNullParamOrThrowFacts != null) { |
| for (int i = 0; i < arguments.size(); i++) { |
| if (nonNullParamOrThrowFacts.get(i)) { |
| TypeElement type = arguments.get(i).getType(); |
| if (type.isClassType()) { |
| enqueue(type.asClassType().getClassType(), visited, worklist); |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
