| // Copyright (c) 2017, 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.optimize; |
| |
| import com.android.tools.r8.errors.CompilationError; |
| import com.android.tools.r8.graph.DexClass; |
| import com.android.tools.r8.graph.DexEncodedField; |
| import com.android.tools.r8.graph.DexEncodedMethod; |
| import com.android.tools.r8.graph.DexEncodedMethod.TrivialInitializer; |
| import com.android.tools.r8.graph.DexEncodedMethod.TrivialInitializer.TrivialClassInitializer; |
| import com.android.tools.r8.graph.DexField; |
| import com.android.tools.r8.graph.DexItem; |
| import com.android.tools.r8.graph.DexMethod; |
| import com.android.tools.r8.graph.DexType; |
| import com.android.tools.r8.ir.code.ConstNumber; |
| import com.android.tools.r8.ir.code.IRCode; |
| 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.InvokeMethod; |
| 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.ir.code.ValueType; |
| import com.android.tools.r8.shaking.Enqueuer.AppInfoWithLiveness; |
| import com.android.tools.r8.shaking.ProguardMemberRule; |
| import java.util.function.Predicate; |
| |
| public class MemberValuePropagation { |
| |
| private final AppInfoWithLiveness appInfo; |
| |
| private enum RuleType { |
| NONE, |
| ASSUME_NO_SIDE_EFFECTS, |
| ASSUME_VALUES |
| } |
| |
| private static class ProguardMemberRuleLookup { |
| |
| final RuleType type; |
| final ProguardMemberRule rule; |
| |
| ProguardMemberRuleLookup(RuleType type, ProguardMemberRule rule) { |
| this.type = type; |
| this.rule = rule; |
| } |
| } |
| |
| public MemberValuePropagation(AppInfoWithLiveness appInfo) { |
| this.appInfo = appInfo; |
| } |
| |
| private ProguardMemberRuleLookup lookupMemberRule(DexItem item) { |
| ProguardMemberRule rule = appInfo.noSideEffects.get(item); |
| if (rule != null) { |
| return new ProguardMemberRuleLookup(RuleType.ASSUME_NO_SIDE_EFFECTS, rule); |
| } |
| rule = appInfo.assumedValues.get(item); |
| if (rule != null) { |
| return new ProguardMemberRuleLookup(RuleType.ASSUME_VALUES, rule); |
| } |
| return null; |
| } |
| |
| private Instruction constantReplacementFromProguardRule( |
| ProguardMemberRule rule, IRCode code, Instruction instruction) { |
| // Check if this value can be assumed constant. |
| Instruction replacement = null; |
| ValueType valueType = instruction.outValue().outType(); |
| if (rule != null && rule.hasReturnValue() && rule.getReturnValue().isSingleValue()) { |
| Value value = code.createValue(valueType, instruction.getLocalInfo()); |
| assert valueType != ValueType.OBJECT || rule.getReturnValue().isNull(); |
| replacement = new ConstNumber(value, rule.getReturnValue().getSingleValue()); |
| } |
| if (replacement == null && |
| rule != null && rule.hasReturnValue() && rule.getReturnValue().isField()) { |
| DexField field = rule.getReturnValue().getField(); |
| assert ValueType.fromDexType(field.type) == valueType; |
| DexEncodedField staticField = appInfo.lookupStaticTarget(field.clazz, field); |
| if (staticField != null) { |
| Value value = code.createValue(valueType, instruction.getLocalInfo()); |
| replacement = staticField.getStaticValue().asConstInstruction(false, value); |
| } else { |
| throw new CompilationError(field.clazz.toSourceString() + "." + field.name.toString() + |
| " used in assumevalues rule does not exist."); |
| } |
| } |
| return replacement; |
| } |
| |
| private void setValueRangeFromProguardRule(ProguardMemberRule rule, Value value) { |
| if (rule.hasReturnValue() && rule.getReturnValue().isValueRange()) { |
| assert !rule.getReturnValue().isSingleValue(); |
| value.setValueRange(rule.getReturnValue().getValueRange()); |
| } |
| } |
| |
| private void replaceInstructionFromProguardRule(RuleType ruleType, InstructionIterator iterator, |
| Instruction current, Instruction replacement) { |
| if (ruleType == RuleType.ASSUME_NO_SIDE_EFFECTS) { |
| iterator.replaceCurrentInstruction(replacement); |
| } else { |
| if (current.outValue() != null) { |
| assert replacement.outValue() != null; |
| current.outValue().replaceUsers(replacement.outValue()); |
| } |
| replacement.setPosition(current.getPosition()); |
| iterator.add(replacement); |
| } |
| } |
| |
| /** |
| * Replace invoke targets and field accesses with constant values where possible. |
| * <p> |
| * Also assigns value ranges to values where possible. |
| */ |
| public void rewriteWithConstantValues( |
| IRCode code, DexType callingContext, Predicate<DexEncodedMethod> isProcessedConcurrently) { |
| InstructionIterator iterator = code.instructionIterator(); |
| while (iterator.hasNext()) { |
| Instruction current = iterator.next(); |
| if (current.isInvokeMethod()) { |
| InvokeMethod invoke = current.asInvokeMethod(); |
| DexMethod invokedMethod = invoke.getInvokedMethod(); |
| DexType invokedHolder = invokedMethod.getHolder(); |
| if (!invokedHolder.isClassType()) { |
| continue; |
| } |
| // TODO(70550443): Maybe check all methods here. |
| DexEncodedMethod definition = appInfo |
| .lookup(invoke.getType(), invokedMethod, callingContext); |
| |
| boolean invokeReplaced = false; |
| ProguardMemberRuleLookup lookup = lookupMemberRule(definition); |
| if (lookup != null) { |
| if (lookup.type == RuleType.ASSUME_NO_SIDE_EFFECTS |
| && (invoke.outValue() == null || !invoke.outValue().isUsed())) { |
| // Remove invoke if marked as having no side effects and the return value is not used. |
| iterator.remove(); |
| invokeReplaced = true; |
| } else if (invoke.outValue() != null && invoke.outValue().isUsed()) { |
| // Check to see if a constant value can be assumed. |
| Instruction replacement = |
| constantReplacementFromProguardRule(lookup.rule, code, invoke); |
| if (replacement != null) { |
| replaceInstructionFromProguardRule(lookup.type, iterator, current, replacement); |
| invokeReplaced = true; |
| } else { |
| // Check to see if a value range can be assumed. |
| setValueRangeFromProguardRule(lookup.rule, current.outValue()); |
| } |
| } |
| } |
| |
| // If no Proguard rule could replace the instruction check for knowledge about the |
| // return value. |
| if (!invokeReplaced && invoke.outValue() != null) { |
| DexEncodedMethod target = invoke.computeSingleTarget(appInfo); |
| if (target != null) { |
| if (target.getOptimizationInfo().neverReturnsNull() && invoke.outValue().canBeNull()) { |
| invoke.outValue().markNeverNull(); |
| } |
| if (target.getOptimizationInfo().returnsConstant()) { |
| long constant = target.getOptimizationInfo().getReturnedConstant(); |
| ValueType valueType = invoke.outType(); |
| Value value = code.createValue(valueType); |
| Instruction knownConstReturn = new ConstNumber(value, constant); |
| invoke.outValue().replaceUsers(value); |
| knownConstReturn.setPosition(invoke.getPosition()); |
| iterator.add(knownConstReturn); |
| } |
| } |
| } |
| } else if (current.isInstancePut()) { |
| InstancePut instancePut = current.asInstancePut(); |
| DexField field = instancePut.getField(); |
| DexEncodedField target = appInfo.lookupInstanceTarget(field.getHolder(), field); |
| if (target != null) { |
| // Remove writes to dead (i.e. never read) fields. |
| if (!isFieldRead(target, false) && instancePut.object().isNeverNull()) { |
| iterator.remove(); |
| } |
| } |
| } else if (current.isStaticGet()) { |
| StaticGet staticGet = current.asStaticGet(); |
| DexField field = staticGet.getField(); |
| DexEncodedField target = appInfo.lookupStaticTarget(field.getHolder(), field); |
| ProguardMemberRuleLookup lookup = null; |
| if (target != null) { |
| // Check if a this value is known const. |
| Instruction replacement = target.valueAsConstInstruction(appInfo, staticGet.dest()); |
| if (replacement == null) { |
| lookup = lookupMemberRule(target); |
| if (lookup != null) { |
| replacement = constantReplacementFromProguardRule(lookup.rule, code, staticGet); |
| } |
| } |
| if (replacement == null) { |
| // If no const replacement was found, at least store the range information. |
| if (lookup != null) { |
| setValueRangeFromProguardRule(lookup.rule, staticGet.dest()); |
| } |
| } |
| if (replacement != null) { |
| // Ignore assumenosideeffects for fields. |
| if (lookup != null && lookup.type == RuleType.ASSUME_VALUES) { |
| replaceInstructionFromProguardRule(lookup.type, iterator, current, replacement); |
| } else { |
| iterator.replaceCurrentInstruction(replacement); |
| } |
| } else if (staticGet.dest() != null) { |
| // In case the class holder of this static field satisfying following criteria: |
| // -- cannot trigger other static initializer except for its own |
| // -- is final |
| // -- has a class initializer which is classified as trivial |
| // (see CodeRewriter::computeClassInitializerInfo) and |
| // initializes the field being accessed |
| // |
| // ... and the field itself is not pinned by keep rules (in which case it might |
| // be updated outside the class constructor, e.g. via reflections), it is safe |
| // to assume that the static-get instruction reads the value it initialized value |
| // in class initializer and is never null. |
| // |
| DexClass holderDefinition = appInfo.definitionFor(field.getHolder()); |
| if (holderDefinition != null && |
| holderDefinition.accessFlags.isFinal() && |
| !appInfo.canTriggerStaticInitializer(field.getHolder(), true)) { |
| |
| Value outValue = staticGet.dest(); |
| DexEncodedMethod classInitializer = holderDefinition.getClassInitializer(); |
| if (classInitializer != null && !isProcessedConcurrently.test(classInitializer)) { |
| TrivialInitializer info = |
| classInitializer.getOptimizationInfo().getTrivialInitializerInfo(); |
| if (info != null && |
| ((TrivialClassInitializer) info).field == field && |
| !appInfo.isPinned(field) && |
| outValue.canBeNull()) { |
| outValue.markNeverNull(); |
| } |
| } |
| } |
| } |
| } |
| } else if (current.isStaticPut()) { |
| StaticPut staticPut = current.asStaticPut(); |
| DexField field = staticPut.getField(); |
| DexEncodedField target = appInfo.lookupStaticTarget(field.getHolder(), field); |
| if (target != null) { |
| // Remove writes to dead (i.e. never read) fields. |
| if (!isFieldRead(target, true)) { |
| iterator.remove(); |
| } |
| } |
| } |
| } |
| assert code.isConsistentSSA(); |
| } |
| |
| private boolean isFieldRead(DexEncodedField field, boolean isStatic) { |
| if (appInfo.fieldsRead.contains(field.field) |
| || appInfo.isPinned(field.field)) { |
| return true; |
| } |
| // For library classes we don't know whether a field is read. |
| DexClass holder = appInfo.definitionFor(field.field.clazz); |
| return holder == null || holder.isLibraryClass(); |
| } |
| } |
