| // Copyright (c) 2012, the Dart 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. |
| |
| part of ssa; |
| |
| abstract class OptimizationPhase { |
| String get name; |
| void visitGraph(HGraph graph); |
| } |
| |
| class SsaOptimizerTask extends CompilerTask { |
| final JavaScriptBackend backend; |
| SsaOptimizerTask(JavaScriptBackend backend) |
| : this.backend = backend, |
| super(backend.compiler); |
| String get name => 'SSA optimizer'; |
| Compiler get compiler => backend.compiler; |
| |
| void runPhases(HGraph graph, List<OptimizationPhase> phases) { |
| for (OptimizationPhase phase in phases) { |
| runPhase(graph, phase); |
| } |
| } |
| |
| void runPhase(HGraph graph, OptimizationPhase phase) { |
| phase.visitGraph(graph); |
| compiler.tracer.traceGraph(phase.name, graph); |
| assert(graph.isValid()); |
| } |
| |
| void optimize(CodegenWorkItem work, HGraph graph, bool speculative) { |
| ConstantSystem constantSystem = compiler.backend.constantSystem; |
| JavaScriptItemCompilationContext context = work.compilationContext; |
| measure(() { |
| List<OptimizationPhase> phases = <OptimizationPhase>[ |
| // Run trivial constant folding first to optimize |
| // some patterns useful for type conversion. |
| new SsaConstantFolder(constantSystem, backend, work), |
| new SsaTypeConversionInserter(compiler), |
| new SsaNonSpeculativeTypePropagator(compiler), |
| new SsaConstantFolder(constantSystem, backend, work), |
| // The constant folder affects the types of instructions, so |
| // we run the type propagator again. Note that this would |
| // not be necessary if types were directly stored on |
| // instructions. |
| new SsaNonSpeculativeTypePropagator(compiler), |
| new SsaCheckInserter(backend, work, context.boundsChecked), |
| new SsaRedundantPhiEliminator(), |
| new SsaDeadPhiEliminator(), |
| new SsaConstantFolder(constantSystem, backend, work), |
| new SsaNonSpeculativeTypePropagator(compiler), |
| new SsaGlobalValueNumberer(compiler), |
| new SsaCodeMotion(), |
| new SsaValueRangeAnalyzer(compiler, constantSystem, work), |
| // Previous optimizations may have generated new |
| // opportunities for constant folding. |
| new SsaConstantFolder(constantSystem, backend, work), |
| new SsaSimplifyInterceptors(compiler, constantSystem, work), |
| new SsaDeadCodeEliminator()]; |
| runPhases(graph, phases); |
| if (!speculative) { |
| runPhase(graph, new SsaConstructionFieldTypes(backend, work)); |
| } |
| }); |
| } |
| |
| bool trySpeculativeOptimizations(CodegenWorkItem work, HGraph graph) { |
| if (work.element.isField()) { |
| // Lazy initializers may not have bailout methods. |
| return false; |
| } |
| JavaScriptItemCompilationContext context = work.compilationContext; |
| ConstantSystem constantSystem = compiler.backend.constantSystem; |
| return measure(() { |
| SsaTypeGuardInserter inserter = new SsaTypeGuardInserter(compiler, work); |
| |
| // Run the phases that will generate type guards. |
| List<OptimizationPhase> phases = <OptimizationPhase>[ |
| inserter, |
| new SsaEnvironmentBuilder(compiler), |
| // Then run the [SsaCheckInserter] because the type propagator also |
| // propagated types non-speculatively. For example, it might have |
| // propagated the type array for a call to the List constructor. |
| new SsaCheckInserter(backend, work, context.boundsChecked)]; |
| runPhases(graph, phases); |
| |
| if (work.guards.isEmpty && inserter.hasInsertedChecks) { |
| // If there is no guard, and we have inserted type checks |
| // instead, we can do the optimizations right away and avoid |
| // the bailout method. |
| optimize(work, graph, false); |
| } |
| return !work.guards.isEmpty; |
| }); |
| } |
| |
| void prepareForSpeculativeOptimizations(CodegenWorkItem work, HGraph graph) { |
| JavaScriptItemCompilationContext context = work.compilationContext; |
| measure(() { |
| // In order to generate correct code for the bailout version, we did not |
| // propagate types from the instruction to the type guard. We do it |
| // now to be able to optimize further. |
| work.guards.forEach((HTypeGuard guard) { |
| guard.bailoutTarget.disable(); |
| guard.enable(); |
| }); |
| // We also need to insert range and integer checks for the type |
| // guards. Now that they claim to have a certain type, some |
| // depending instructions might become builtin (like native array |
| // accesses) and need to be checked. |
| // Also run the type propagator, to please the codegen in case |
| // no other optimization is run. |
| runPhases(graph, <OptimizationPhase>[ |
| new SsaCheckInserter(backend, work, context.boundsChecked), |
| new SsaNonSpeculativeTypePropagator(compiler)]); |
| }); |
| } |
| } |
| |
| /** |
| * If both inputs to known operations are available execute the operation at |
| * compile-time. |
| */ |
| class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase { |
| final String name = "SsaConstantFolder"; |
| final JavaScriptBackend backend; |
| final CodegenWorkItem work; |
| final ConstantSystem constantSystem; |
| HGraph graph; |
| Compiler get compiler => backend.compiler; |
| |
| SsaConstantFolder(this.constantSystem, this.backend, this.work); |
| |
| void visitGraph(HGraph visitee) { |
| graph = visitee; |
| visitDominatorTree(visitee); |
| } |
| |
| visitBasicBlock(HBasicBlock block) { |
| HInstruction instruction = block.first; |
| while (instruction != null) { |
| HInstruction next = instruction.next; |
| HInstruction replacement = instruction.accept(this); |
| if (replacement != instruction) { |
| block.rewrite(instruction, replacement); |
| |
| // If we can replace [instruction] with [replacement], then |
| // [replacement]'s type can be narrowed. |
| HType newType = replacement.instructionType.intersection( |
| instruction.instructionType, compiler); |
| if (!newType.isConflicting()) { |
| // [HType.intersection] may give up when doing the |
| // intersection of two types is too complicated, and return |
| // [HType.CONFLICTING]. We do not want instructions to have |
| // [HType.CONFLICTING], so we only update the type if the |
| // intersection did not give up. |
| replacement.instructionType = newType; |
| } |
| |
| // If the replacement instruction does not know its |
| // source element, use the source element of the |
| // instruction. |
| if (replacement.sourceElement == null) { |
| replacement.sourceElement = instruction.sourceElement; |
| } |
| if (replacement.sourcePosition == null) { |
| replacement.sourcePosition = instruction.sourcePosition; |
| } |
| if (!replacement.isInBasicBlock()) { |
| // The constant folding can return an instruction that is already |
| // part of the graph (like an input), so we only add the replacement |
| // if necessary. |
| block.addAfter(instruction, replacement); |
| // Visit the replacement as the next instruction in case it |
| // can also be constant folded away. |
| next = replacement; |
| } |
| block.remove(instruction); |
| } |
| instruction = next; |
| } |
| } |
| |
| HInstruction visitInstruction(HInstruction node) { |
| return node; |
| } |
| |
| HInstruction visitBoolify(HBoolify node) { |
| List<HInstruction> inputs = node.inputs; |
| assert(inputs.length == 1); |
| HInstruction input = inputs[0]; |
| HType type = input.instructionType; |
| if (type.isBoolean()) return input; |
| // All values that cannot be 'true' are boolified to false. |
| DartType booleanType = backend.jsBoolClass.computeType(compiler); |
| TypeMask mask = type.computeMask(compiler); |
| // TODO(kasperl): Get rid of the null check here once all HTypes |
| // have a proper mask. |
| if (mask != null && !mask.contains(booleanType, compiler)) { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| return node; |
| } |
| |
| HInstruction visitNot(HNot node) { |
| List<HInstruction> inputs = node.inputs; |
| assert(inputs.length == 1); |
| HInstruction input = inputs[0]; |
| if (input is HConstant) { |
| HConstant constant = input; |
| bool isTrue = constant.constant.isTrue(); |
| return graph.addConstantBool(!isTrue, constantSystem); |
| } else if (input is HNot) { |
| return input.inputs[0]; |
| } |
| return node; |
| } |
| |
| HInstruction visitInvokeUnary(HInvokeUnary node) { |
| HInstruction folded = |
| foldUnary(node.operation(constantSystem), node.operand); |
| return folded != null ? folded : node; |
| } |
| |
| HInstruction foldUnary(UnaryOperation operation, HInstruction operand) { |
| if (operand is HConstant) { |
| HConstant receiver = operand; |
| Constant folded = operation.fold(receiver.constant); |
| if (folded != null) return graph.addConstant(folded); |
| } |
| return null; |
| } |
| |
| HInstruction tryOptimizeLengthInterceptedGetter(HInvokeDynamic node) { |
| HInstruction actualReceiver = node.inputs[1]; |
| if (actualReceiver.isIndexable(compiler)) { |
| if (actualReceiver.isConstantString()) { |
| HConstant constantInput = actualReceiver; |
| StringConstant constant = constantInput.constant; |
| return graph.addConstantInt(constant.length, constantSystem); |
| } else if (actualReceiver.isConstantList()) { |
| HConstant constantInput = actualReceiver; |
| ListConstant constant = constantInput.constant; |
| return graph.addConstantInt(constant.length, constantSystem); |
| } |
| Element element = backend.jsIndexableLength; |
| bool isAssignable = !actualReceiver.isFixedArray(compiler) && |
| !actualReceiver.isString(); |
| HFieldGet result = new HFieldGet( |
| element, actualReceiver, isAssignable: isAssignable); |
| result.instructionType = HType.INTEGER; |
| return result; |
| } else if (actualReceiver.isConstantMap()) { |
| HConstant constantInput = actualReceiver; |
| MapConstant constant = constantInput.constant; |
| return graph.addConstantInt(constant.length, constantSystem); |
| } |
| return null; |
| } |
| |
| HInstruction handleInterceptedCall(HInvokeDynamic node) { |
| // Try constant folding the instruction. |
| Operation operation = node.specializer.operation(constantSystem); |
| if (operation != null) { |
| HInstruction instruction = node.inputs.length == 2 |
| ? foldUnary(operation, node.inputs[1]) |
| : foldBinary(operation, node.inputs[1], node.inputs[2]); |
| if (instruction != null) return instruction; |
| } |
| |
| // Try converting the instruction to a builtin instruction. |
| HInstruction instruction = |
| node.specializer.tryConvertToBuiltin(node, compiler); |
| if (instruction != null) return instruction; |
| |
| Selector selector = node.selector; |
| HInstruction input = node.inputs[1]; |
| |
| if (selector.isCall()) { |
| Element target; |
| if (input.isExtendableArray(compiler)) { |
| if (selector.applies(backend.jsArrayRemoveLast, compiler)) { |
| target = backend.jsArrayRemoveLast; |
| } else if (selector.applies(backend.jsArrayAdd, compiler)) { |
| // The codegen special cases array calls, but does not |
| // inline argument type checks. |
| if (!compiler.enableTypeAssertions) { |
| target = backend.jsArrayAdd; |
| } |
| } |
| } else if (input.isString()) { |
| if (selector.applies(backend.jsStringSplit, compiler)) { |
| if (node.inputs[2].isString()) { |
| target = backend.jsStringSplit; |
| } |
| } else if (selector.applies(backend.jsStringConcat, compiler)) { |
| if (node.inputs[2].isString()) { |
| target = backend.jsStringConcat; |
| } |
| } else if (selector.applies(backend.jsStringToString, compiler)) { |
| return input; |
| } |
| } |
| if (target != null) { |
| // TODO(ngeoffray): There is a strong dependency between codegen |
| // and this optimization that the dynamic invoke does not need an |
| // interceptor. We currently need to keep a |
| // HInvokeDynamicMethod and not create a HForeign because |
| // HForeign is too opaque for the SsaCheckInserter (that adds a |
| // bounds check on removeLast). Once we start inlining, the |
| // bounds check will become explicit, so we won't need this |
| // optimization. |
| HInvokeDynamicMethod result = new HInvokeDynamicMethod( |
| node.selector, node.inputs.sublist(1)); |
| result.element = target; |
| return result; |
| } |
| } else if (selector.isGetter()) { |
| if (selector.asUntyped.applies(backend.jsIndexableLength, compiler)) { |
| HInstruction optimized = tryOptimizeLengthInterceptedGetter(node); |
| if (optimized != null) return optimized; |
| } |
| } |
| |
| return node; |
| } |
| |
| HInstruction visitInvokeDynamicMethod(HInvokeDynamicMethod node) { |
| if (node.isInterceptedCall) { |
| HInstruction folded = handleInterceptedCall(node); |
| if (folded != node) return folded; |
| } |
| |
| HType receiverType = node.getDartReceiver(compiler).instructionType; |
| Selector selector = receiverType.refine(node.selector, compiler); |
| Element element = compiler.world.locateSingleElement(selector); |
| // TODO(ngeoffray): Also fold if it's a getter or variable. |
| if (element != null |
| && element.isFunction() |
| // If we found out that the only target is a [:noSuchMethod:], |
| // we just ignore it. |
| && element.name == selector.name) { |
| FunctionElement method = element; |
| |
| if (method.isNative()) { |
| HInstruction folded = tryInlineNativeMethod(node, method); |
| if (folded != null) return folded; |
| } else { |
| // TODO(ngeoffray): If the method has optional parameters, |
| // we should pass the default values. |
| FunctionSignature parameters = method.computeSignature(compiler); |
| if (parameters.optionalParameterCount == 0 |
| || parameters.parameterCount == node.selector.argumentCount) { |
| node.element = element; |
| } |
| } |
| } |
| return node; |
| } |
| |
| HInstruction tryInlineNativeMethod(HInvokeDynamicMethod node, |
| FunctionElement method) { |
| // Enable direct calls to a native method only if we don't run in checked |
| // mode, where the Dart version may have type annotations on parameters and |
| // return type that it should check. |
| // Also check that the parameters are not functions: it's the callee that |
| // will translate them to JS functions. |
| // |
| // TODO(ngeoffray): There are some cases where we could still inline in |
| // checked mode if we know the arguments have the right type. And we could |
| // do the closure conversion as well as the return type annotation check. |
| |
| if (!node.isInterceptedCall) return null; |
| |
| // TODO(sra): Check for legacy methods with bodies in the native strings. |
| // foo() native 'return something'; |
| // They should not be used. |
| |
| FunctionSignature signature = method.computeSignature(compiler); |
| if (signature.optionalParametersAreNamed) return null; |
| |
| // Return types on native methods don't need to be checked, since the |
| // declaration has to be truthful. |
| |
| // The call site might omit optional arguments. The inlined code must |
| // preserve the number of arguments, so check only the actual arguments. |
| |
| List<HInstruction> inputs = node.inputs.sublist(1); |
| int inputPosition = 1; // Skip receiver. |
| bool canInline = true; |
| signature.forEachParameter((Element element) { |
| if (inputPosition < inputs.length && canInline) { |
| HInstruction input = inputs[inputPosition++]; |
| DartType type = element.computeType(compiler).unalias(compiler); |
| if (type is FunctionType) { |
| canInline = false; |
| } |
| if (compiler.enableTypeAssertions) { |
| // TODO(sra): Check if [input] is guaranteed to pass the parameter |
| // type check. Consider using a strengthened type check to avoid |
| // passing `null` to primitive types since the native methods usually |
| // have non-nullable primitive parameter types. |
| canInline = false; |
| } |
| } |
| }); |
| |
| if (!canInline) return null; |
| |
| HInvokeDynamicMethod result = |
| new HInvokeDynamicMethod(node.selector, inputs); |
| result.element = method; |
| |
| // Strengthen instruction type from annotations to help optimize |
| // dependent instructions. |
| native.NativeBehavior nativeBehavior = |
| native.NativeBehavior.ofMethod(method, compiler); |
| HType returnType = new HType.fromNativeBehavior(nativeBehavior, compiler); |
| result.instructionType = returnType; |
| return result; |
| } |
| |
| HInstruction visitBoundsCheck(HBoundsCheck node) { |
| HInstruction index = node.index; |
| if (index.isInteger()) return node; |
| if (index.isConstant()) { |
| HConstant constantInstruction = index; |
| assert(!constantInstruction.constant.isInt()); |
| if (!constantSystem.isInt(constantInstruction.constant)) { |
| // -0.0 is a double but will pass the runtime integer check. |
| node.staticChecks = HBoundsCheck.ALWAYS_FALSE; |
| } |
| } |
| return node; |
| } |
| |
| HInstruction foldBinary(BinaryOperation operation, |
| HInstruction left, |
| HInstruction right) { |
| if (left is HConstant && right is HConstant) { |
| HConstant op1 = left; |
| HConstant op2 = right; |
| Constant folded = operation.fold(op1.constant, op2.constant); |
| if (folded != null) return graph.addConstant(folded); |
| } |
| return null; |
| } |
| |
| HInstruction visitInvokeBinary(HInvokeBinary node) { |
| HInstruction left = node.left; |
| HInstruction right = node.right; |
| BinaryOperation operation = node.operation(constantSystem); |
| HConstant folded = foldBinary(operation, left, right); |
| if (folded != null) return folded; |
| return node; |
| } |
| |
| bool allUsersAreBoolifies(HInstruction instruction) { |
| List<HInstruction> users = instruction.usedBy; |
| int length = users.length; |
| for (int i = 0; i < length; i++) { |
| if (users[i] is! HBoolify) return false; |
| } |
| return true; |
| } |
| |
| HInstruction visitRelational(HRelational node) { |
| if (allUsersAreBoolifies(node)) { |
| // TODO(ngeoffray): Call a boolified selector. |
| // This node stays the same, but the Boolify node will go away. |
| } |
| // Note that we still have to call [super] to make sure that we end up |
| // in the remaining optimizations. |
| return super.visitRelational(node); |
| } |
| |
| HInstruction handleIdentityCheck(HRelational node) { |
| HInstruction left = node.left; |
| HInstruction right = node.right; |
| HType leftType = left.instructionType; |
| HType rightType = right.instructionType; |
| |
| // Intersection of int and double return conflicting, so |
| // we don't optimize on numbers to preserve the runtime semantics. |
| if (!(left.isNumberOrNull() && right.isNumberOrNull()) && |
| leftType.intersection(rightType, compiler).isConflicting()) { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| |
| if (left.isNull() && right.isNull()) { |
| return graph.addConstantBool(true, constantSystem); |
| } |
| |
| if (left.isConstantBoolean() && right.isBoolean()) { |
| HConstant constant = left; |
| if (constant.constant.isTrue()) { |
| return right; |
| } else { |
| return new HNot(right); |
| } |
| } |
| |
| if (right.isConstantBoolean() && left.isBoolean()) { |
| HConstant constant = right; |
| if (constant.constant.isTrue()) { |
| return left; |
| } else { |
| return new HNot(left); |
| } |
| } |
| |
| return null; |
| } |
| |
| HInstruction visitIdentity(HIdentity node) { |
| HInstruction newInstruction = handleIdentityCheck(node); |
| return newInstruction == null ? super.visitIdentity(node) : newInstruction; |
| } |
| |
| HInstruction visitTypeGuard(HTypeGuard node) { |
| HInstruction value = node.guarded; |
| // If the intersection of the types is still the incoming type then |
| // the incoming type was a subtype of the guarded type, and no check |
| // is required. |
| HType combinedType = |
| value.instructionType.intersection(node.guardedType, compiler); |
| return (combinedType == value.instructionType) ? value : node; |
| } |
| |
| HInstruction visitIs(HIs node) { |
| DartType type = node.typeExpression; |
| Element element = type.element; |
| |
| if (!node.isRawCheck) { |
| return node; |
| } else if (element.isTypedef()) { |
| return node; |
| } else if (element == compiler.functionClass) { |
| return node; |
| } |
| |
| if (element == compiler.objectClass || element == compiler.dynamicClass) { |
| return graph.addConstantBool(true, constantSystem); |
| } |
| |
| HType expressionType = node.expression.instructionType; |
| if (expressionType.isInteger()) { |
| if (identical(element, compiler.intClass) |
| || identical(element, compiler.numClass) |
| || Elements.isNumberOrStringSupertype(element, compiler)) { |
| return graph.addConstantBool(true, constantSystem); |
| } else if (identical(element, compiler.doubleClass)) { |
| // We let the JS semantics decide for that check. Currently |
| // the code we emit will always return true. |
| return node; |
| } else { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| } else if (expressionType.isDouble()) { |
| if (identical(element, compiler.doubleClass) |
| || identical(element, compiler.numClass) |
| || Elements.isNumberOrStringSupertype(element, compiler)) { |
| return graph.addConstantBool(true, constantSystem); |
| } else if (identical(element, compiler.intClass)) { |
| // We let the JS semantics decide for that check. Currently |
| // the code we emit will return true for a double that can be |
| // represented as a 31-bit integer and for -0.0. |
| return node; |
| } else { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| } else if (expressionType.isNumber()) { |
| if (identical(element, compiler.numClass)) { |
| return graph.addConstantBool(true, constantSystem); |
| } |
| // We cannot just return false, because the expression may be of |
| // type int or double. |
| } else if (expressionType.isString()) { |
| if (identical(element, compiler.stringClass) |
| || Elements.isStringOnlySupertype(element, compiler) |
| || Elements.isNumberOrStringSupertype(element, compiler)) { |
| return graph.addConstantBool(true, constantSystem); |
| } else { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| // We need the [:hasTypeArguments:] check because we don't have |
| // the notion of generics in the backend. For example, [:this:] in |
| // a class [:A<T>:], is currently always considered to have the |
| // raw type. |
| } else if (!RuntimeTypes.hasTypeArguments(type) && !type.isMalformed) { |
| TypeMask expressionMask = expressionType.computeMask(compiler); |
| TypeMask typeMask = new TypeMask.nonNullSubtype(type); |
| if (expressionMask.union(typeMask, compiler) == typeMask) { |
| return graph.addConstantBool(true, constantSystem); |
| } else if (expressionMask.intersection(typeMask, compiler).isEmpty) { |
| return graph.addConstantBool(false, constantSystem); |
| } |
| } |
| return node; |
| } |
| |
| HInstruction visitTypeConversion(HTypeConversion node) { |
| HInstruction value = node.inputs[0]; |
| DartType type = node.typeExpression; |
| if (type != null && (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE)) { |
| return node; |
| } |
| HType convertedType = node.instructionType; |
| if (convertedType.isUnknown()) return node; |
| HType combinedType = value.instructionType.intersection( |
| convertedType, compiler); |
| return (combinedType == value.instructionType) ? value : node; |
| } |
| |
| Element findConcreteFieldForDynamicAccess(HInstruction receiver, |
| Selector selector) { |
| HType receiverType = receiver.instructionType; |
| return compiler.world.locateSingleField( |
| receiverType.refine(selector, compiler)); |
| } |
| |
| HInstruction visitFieldGet(HFieldGet node) { |
| if (node.element == backend.jsIndexableLength) { |
| if (node.receiver is HInvokeStatic) { |
| // Try to recognize the length getter with input |
| // [:new List(int):]. |
| HInvokeStatic call = node.receiver; |
| Element element = call.element; |
| // TODO(ngeoffray): checking if the second input is an integer |
| // should not be necessary but it currently makes it easier for |
| // other optimizations to reason about a fixed length constructor |
| // that we know takes an int. |
| if (element == compiler.unnamedListConstructor |
| && call.inputs.length == 1 |
| && call.inputs[0].isInteger()) { |
| return call.inputs[0]; |
| } |
| } else if (node.receiver.isConstantList() || |
| node.receiver.isConstantString()) { |
| var instruction = node.receiver; |
| return graph.addConstantInt( |
| instruction.constant.length, backend.constantSystem); |
| } |
| } |
| return node; |
| } |
| |
| HInstruction visitIndex(HIndex node) { |
| if (node.receiver.isConstantList() && node.index.isConstantInteger()) { |
| var instruction = node.receiver; |
| List<Constant> entries = instruction.constant.entries; |
| instruction = node.index; |
| int index = instruction.constant.value; |
| if (index >= 0 && index < entries.length) { |
| return graph.addConstant(entries[index]); |
| } |
| } |
| return node; |
| } |
| |
| HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) { |
| if (node.isInterceptedCall) { |
| HInstruction folded = handleInterceptedCall(node); |
| if (folded != node) return folded; |
| } |
| HInstruction receiver = node.getDartReceiver(compiler); |
| Element field = findConcreteFieldForDynamicAccess(receiver, node.selector); |
| if (field == null) return node; |
| return directFieldGet(receiver, field); |
| } |
| |
| HInstruction directFieldGet(HInstruction receiver, Element field) { |
| Modifiers modifiers = field.modifiers; |
| bool isAssignable = !(modifiers.isFinal() || modifiers.isConst()); |
| if (!compiler.resolverWorld.hasInvokedSetter(field, compiler)) { |
| // If no setter is ever used for this field it is only initialized in the |
| // initializer list. |
| isAssignable = false; |
| } |
| if (field.isNative()) { |
| // Some native fields are views of data that may be changed by operations. |
| // E.g. node.firstChild depends on parentNode.removeBefore(n1, n2). |
| // TODO(sra): Refine the effect classification so that native effects are |
| // distinct from ordinary Dart effects. |
| isAssignable = true; |
| } |
| HFieldGet result = new HFieldGet( |
| field, receiver, isAssignable: isAssignable); |
| |
| if (field.getEnclosingClass().isNative()) { |
| result.instructionType = new HType.fromNativeBehavior( |
| native.NativeBehavior.ofFieldLoad(field, compiler), |
| compiler); |
| } else { |
| HType type = new HType.inferredTypeForElement(field, compiler); |
| if (type.isUnknown()) { |
| type = backend.optimisticFieldType(field); |
| if (type != null) { |
| backend.registerFieldTypesOptimization( |
| work.element, field, result.instructionType); |
| } |
| } |
| if (type != null) { |
| result.instructionType = type; |
| } |
| } |
| return result; |
| } |
| |
| HInstruction visitInvokeDynamicSetter(HInvokeDynamicSetter node) { |
| if (node.isInterceptedCall) { |
| HInstruction folded = handleInterceptedCall(node); |
| if (folded != node) return folded; |
| } |
| |
| HInstruction receiver = node.getDartReceiver(compiler); |
| Element field = findConcreteFieldForDynamicAccess(receiver, node.selector); |
| if (field == null || !field.isAssignable()) return node; |
| // Use [:node.inputs.last:] in case the call follows the |
| // interceptor calling convention, but is not a call on an |
| // interceptor. |
| HInstruction value = node.inputs.last; |
| if (compiler.enableTypeAssertions) { |
| DartType type = field.computeType(compiler); |
| if (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE) { |
| // We cannot generate the correct type representation here, so don't |
| // inline this access. |
| return node; |
| } |
| HInstruction other = value.convertType( |
| compiler, |
| type, |
| HTypeConversion.CHECKED_MODE_CHECK); |
| if (other != value) { |
| node.block.addBefore(node, other); |
| value = other; |
| } |
| } |
| return new HFieldSet(field, receiver, value); |
| } |
| |
| HInstruction visitStringConcat(HStringConcat node) { |
| // Simplify string concat: |
| // |
| // "" + R -> R |
| // L + "" -> L |
| // "L" + "R" -> "LR" |
| // (prefix + "L") + "R" -> prefix + "LR" |
| // |
| StringConstant getString(HInstruction instruction) { |
| if (!instruction.isConstantString()) return null; |
| HConstant constant = instruction; |
| return constant.constant; |
| } |
| |
| StringConstant leftString = getString(node.left); |
| if (leftString != null && leftString.value.length == 0) return node.right; |
| |
| StringConstant rightString = getString(node.right); |
| if (rightString == null) return node; |
| if (rightString.value.length == 0) return node.left; |
| |
| HInstruction prefix = null; |
| if (leftString == null) { |
| if (node.left is! HStringConcat) return node; |
| HStringConcat leftConcat = node.left; |
| // Don't undo CSE. |
| if (leftConcat.usedBy.length != 1) return node; |
| prefix = leftConcat.left; |
| leftString = getString(leftConcat.right); |
| if (leftString == null) return node; |
| } |
| |
| HInstruction folded = |
| graph.addConstant(constantSystem.createString( |
| new DartString.concat(leftString.value, rightString.value), |
| node.node)); |
| if (prefix == null) return folded; |
| return new HStringConcat(prefix, folded, node.node); |
| } |
| |
| HInstruction visitStringify(HStringify node) { |
| HInstruction input = node.inputs[0]; |
| if (input.isString()) return input; |
| if (input.isConstant()) { |
| HConstant constant = input; |
| if (!constant.constant.isPrimitive()) return node; |
| PrimitiveConstant primitive = constant.constant; |
| return graph.addConstant(constantSystem.createString( |
| primitive.toDartString(), node.node)); |
| } |
| return node; |
| } |
| |
| HInstruction visitOneShotInterceptor(HOneShotInterceptor node) { |
| return handleInterceptedCall(node); |
| } |
| } |
| |
| class SsaCheckInserter extends HBaseVisitor implements OptimizationPhase { |
| final Set<HInstruction> boundsChecked; |
| final CodegenWorkItem work; |
| final JavaScriptBackend backend; |
| final String name = "SsaCheckInserter"; |
| HGraph graph; |
| |
| SsaCheckInserter(this.backend, |
| this.work, |
| this.boundsChecked); |
| |
| void visitGraph(HGraph graph) { |
| this.graph = graph; |
| visitDominatorTree(graph); |
| } |
| |
| void visitBasicBlock(HBasicBlock block) { |
| HInstruction instruction = block.first; |
| while (instruction != null) { |
| HInstruction next = instruction.next; |
| instruction = instruction.accept(this); |
| instruction = next; |
| } |
| } |
| |
| HBoundsCheck insertBoundsCheck(HInstruction indexNode, |
| HInstruction array, |
| HInstruction indexArgument) { |
| bool isAssignable = |
| !array.isFixedArray(backend.compiler) && !array.isString(); |
| HFieldGet length = new HFieldGet( |
| backend.jsIndexableLength, array, isAssignable: isAssignable); |
| length.instructionType = HType.INTEGER; |
| indexNode.block.addBefore(indexNode, length); |
| |
| HBoundsCheck check = new HBoundsCheck(indexArgument, length); |
| indexNode.block.addBefore(indexNode, check); |
| // If the index input to the bounds check was not known to be an integer |
| // then we replace its uses with the bounds check, which is known to be an |
| // integer. However, if the input was already an integer we don't do this |
| // because putting in a check instruction might obscure the real nature of |
| // the index eg. if it is a constant. The range information from the |
| // BoundsCheck instruction is attached to the input directly by |
| // visitBoundsCheck in the SsaValueRangeAnalyzer. |
| if (!indexArgument.isInteger()) { |
| indexArgument.replaceAllUsersDominatedBy(indexNode, check); |
| } |
| boundsChecked.add(indexNode); |
| return check; |
| } |
| |
| void visitIndex(HIndex node) { |
| if (boundsChecked.contains(node)) return; |
| HInstruction index = node.index; |
| index = insertBoundsCheck(node, node.receiver, index); |
| } |
| |
| void visitIndexAssign(HIndexAssign node) { |
| if (boundsChecked.contains(node)) return; |
| HInstruction index = node.index; |
| index = insertBoundsCheck(node, node.receiver, index); |
| } |
| |
| void visitInvokeDynamicMethod(HInvokeDynamicMethod node) { |
| Element element = node.element; |
| if (node.isInterceptedCall) return; |
| if (element != backend.jsArrayRemoveLast) return; |
| if (boundsChecked.contains(node)) return; |
| insertBoundsCheck( |
| node, node.receiver, graph.addConstantInt(0, backend.constantSystem)); |
| } |
| } |
| |
| class SsaDeadCodeEliminator extends HGraphVisitor implements OptimizationPhase { |
| final String name = "SsaDeadCodeEliminator"; |
| |
| SsaDeadCodeEliminator(); |
| |
| bool isDeadCode(HInstruction instruction) { |
| return !instruction.sideEffects.hasSideEffects() |
| && !instruction.canThrow() |
| && instruction.usedBy.isEmpty |
| && instruction is !HTypeGuard |
| && instruction is !HParameterValue |
| && instruction is !HLocalSet |
| && !instruction.isControlFlow(); |
| } |
| |
| void visitGraph(HGraph graph) { |
| visitPostDominatorTree(graph); |
| } |
| |
| void visitBasicBlock(HBasicBlock block) { |
| HInstruction instruction = block.last; |
| while (instruction != null) { |
| var previous = instruction.previous; |
| if (isDeadCode(instruction)) block.remove(instruction); |
| instruction = previous; |
| } |
| } |
| } |
| |
| class SsaDeadPhiEliminator implements OptimizationPhase { |
| final String name = "SsaDeadPhiEliminator"; |
| |
| void visitGraph(HGraph graph) { |
| final List<HPhi> worklist = <HPhi>[]; |
| // A set to keep track of the live phis that we found. |
| final Set<HPhi> livePhis = new Set<HPhi>(); |
| |
| // Add to the worklist all live phis: phis referenced by non-phi |
| // instructions. |
| for (final block in graph.blocks) { |
| block.forEachPhi((HPhi phi) { |
| for (final user in phi.usedBy) { |
| if (user is !HPhi) { |
| worklist.add(phi); |
| livePhis.add(phi); |
| break; |
| } |
| } |
| }); |
| } |
| |
| // Process the worklist by propagating liveness to phi inputs. |
| while (!worklist.isEmpty) { |
| HPhi phi = worklist.removeLast(); |
| for (final input in phi.inputs) { |
| if (input is HPhi && !livePhis.contains(input)) { |
| worklist.add(input); |
| livePhis.add(input); |
| } |
| } |
| } |
| |
| // Remove phis that are not live. |
| // Traverse in reverse order to remove phis with no uses before the |
| // phis that they might use. |
| // NOTICE: Doesn't handle circular references, but we don't currently |
| // create any. |
| List<HBasicBlock> blocks = graph.blocks; |
| for (int i = blocks.length - 1; i >= 0; i--) { |
| HBasicBlock block = blocks[i]; |
| HPhi current = block.phis.first; |
| HPhi next = null; |
| while (current != null) { |
| next = current.next; |
| if (!livePhis.contains(current) |
| // TODO(ahe): Not sure the following is correct. |
| && current.usedBy.isEmpty) { |
| block.removePhi(current); |
| } |
| current = next; |
| } |
| } |
| } |
| } |
| |
| class SsaRedundantPhiEliminator implements OptimizationPhase { |
| final String name = "SsaRedundantPhiEliminator"; |
| |
| void visitGraph(HGraph graph) { |
| final List<HPhi> worklist = <HPhi>[]; |
| |
| // Add all phis in the worklist. |
| for (final block in graph.blocks) { |
| block.forEachPhi((HPhi phi) => worklist.add(phi)); |
| } |
| |
| while (!worklist.isEmpty) { |
| HPhi phi = worklist.removeLast(); |
| |
| // If the phi has already been processed, continue. |
| if (!phi.isInBasicBlock()) continue; |
| |
| // Find if the inputs of the phi are the same instruction. |
| // The builder ensures that phi.inputs[0] cannot be the phi |
| // itself. |
| assert(!identical(phi.inputs[0], phi)); |
| HInstruction candidate = phi.inputs[0]; |
| for (int i = 1; i < phi.inputs.length; i++) { |
| HInstruction input = phi.inputs[i]; |
| // If the input is the phi, the phi is still candidate for |
| // elimination. |
| if (!identical(input, candidate) && !identical(input, phi)) { |
| candidate = null; |
| break; |
| } |
| } |
| |
| // If the inputs are not the same, continue. |
| if (candidate == null) continue; |
| |
| // Because we're updating the users of this phi, we may have new |
| // phis candidate for elimination. Add phis that used this phi |
| // to the worklist. |
| for (final user in phi.usedBy) { |
| if (user is HPhi) worklist.add(user); |
| } |
| phi.block.rewrite(phi, candidate); |
| phi.block.removePhi(phi); |
| } |
| } |
| } |
| |
| class SsaGlobalValueNumberer implements OptimizationPhase { |
| final String name = "SsaGlobalValueNumberer"; |
| final Compiler compiler; |
| final Set<int> visited; |
| |
| List<int> blockChangesFlags; |
| List<int> loopChangesFlags; |
| |
| SsaGlobalValueNumberer(this.compiler) : visited = new Set<int>(); |
| |
| void visitGraph(HGraph graph) { |
| computeChangesFlags(graph); |
| moveLoopInvariantCode(graph); |
| visitBasicBlock(graph.entry, new ValueSet()); |
| } |
| |
| void moveLoopInvariantCode(HGraph graph) { |
| for (int i = graph.blocks.length - 1; i >= 0; i--) { |
| HBasicBlock block = graph.blocks[i]; |
| if (block.isLoopHeader()) { |
| int changesFlags = loopChangesFlags[block.id]; |
| HLoopInformation info = block.loopInformation; |
| // Iterate over all blocks of this loop. Note that blocks in |
| // inner loops are not visited here, but we know they |
| // were visited before because we are iterating in post-order. |
| // So instructions that are GVN'ed in an inner loop are in their |
| // loop entry, and [info.blocks] contains this loop entry. |
| for (HBasicBlock other in info.blocks) { |
| moveLoopInvariantCodeFromBlock(other, block, changesFlags); |
| } |
| } |
| } |
| } |
| |
| void moveLoopInvariantCodeFromBlock(HBasicBlock block, |
| HBasicBlock loopHeader, |
| int changesFlags) { |
| assert(block.parentLoopHeader == loopHeader); |
| HBasicBlock preheader = loopHeader.predecessors[0]; |
| int dependsFlags = SideEffects.computeDependsOnFlags(changesFlags); |
| HInstruction instruction = block.first; |
| while (instruction != null) { |
| HInstruction next = instruction.next; |
| if (instruction.useGvn() |
| && !instruction.canThrow() |
| && !instruction.sideEffects.dependsOn(dependsFlags)) { |
| bool loopInvariantInputs = true; |
| List<HInstruction> inputs = instruction.inputs; |
| for (int i = 0, length = inputs.length; i < length; i++) { |
| if (isInputDefinedAfterDominator(inputs[i], preheader)) { |
| loopInvariantInputs = false; |
| break; |
| } |
| } |
| |
| // If the inputs are loop invariant, we can move the |
| // instruction from the current block to the pre-header block. |
| if (loopInvariantInputs) { |
| block.detach(instruction); |
| preheader.moveAtExit(instruction); |
| } |
| } |
| int oldChangesFlags = changesFlags; |
| changesFlags |= instruction.sideEffects.getChangesFlags(); |
| if (oldChangesFlags != changesFlags) { |
| dependsFlags = SideEffects.computeDependsOnFlags(changesFlags); |
| } |
| instruction = next; |
| } |
| } |
| |
| bool isInputDefinedAfterDominator(HInstruction input, |
| HBasicBlock dominator) { |
| return input.block.id > dominator.id; |
| } |
| |
| void visitBasicBlock(HBasicBlock block, ValueSet values) { |
| HInstruction instruction = block.first; |
| if (block.isLoopHeader()) { |
| int flags = loopChangesFlags[block.id]; |
| values.kill(flags); |
| } |
| while (instruction != null) { |
| HInstruction next = instruction.next; |
| int flags = instruction.sideEffects.getChangesFlags(); |
| assert(flags == 0 || !instruction.useGvn()); |
| values.kill(flags); |
| if (instruction.useGvn()) { |
| HInstruction other = values.lookup(instruction); |
| if (other != null) { |
| assert(other.gvnEquals(instruction) && instruction.gvnEquals(other)); |
| block.rewriteWithBetterUser(instruction, other); |
| block.remove(instruction); |
| } else { |
| values.add(instruction); |
| } |
| } |
| instruction = next; |
| } |
| |
| List<HBasicBlock> dominatedBlocks = block.dominatedBlocks; |
| for (int i = 0, length = dominatedBlocks.length; i < length; i++) { |
| HBasicBlock dominated = dominatedBlocks[i]; |
| // No need to copy the value set for the last child. |
| ValueSet successorValues = (i == length - 1) ? values : values.copy(); |
| // If we have no values in our set, we do not have to kill |
| // anything. Also, if the range of block ids from the current |
| // block to the dominated block is empty, there is no blocks on |
| // any path from the current block to the dominated block so we |
| // don't have to do anything either. |
| assert(block.id < dominated.id); |
| if (!successorValues.isEmpty && block.id + 1 < dominated.id) { |
| visited.clear(); |
| int changesFlags = getChangesFlagsForDominatedBlock(block, dominated); |
| successorValues.kill(changesFlags); |
| } |
| visitBasicBlock(dominated, successorValues); |
| } |
| } |
| |
| void computeChangesFlags(HGraph graph) { |
| // Create the changes flags lists. Make sure to initialize the |
| // loop changes flags list to zero so we can use bitwise or when |
| // propagating loop changes upwards. |
| final int length = graph.blocks.length; |
| blockChangesFlags = new List<int>(length); |
| loopChangesFlags = new List<int>(length); |
| for (int i = 0; i < length; i++) loopChangesFlags[i] = 0; |
| |
| // Run through all the basic blocks in the graph and fill in the |
| // changes flags lists. |
| for (int i = length - 1; i >= 0; i--) { |
| final HBasicBlock block = graph.blocks[i]; |
| final int id = block.id; |
| |
| // Compute block changes flags for the block. |
| int changesFlags = 0; |
| HInstruction instruction = block.first; |
| while (instruction != null) { |
| changesFlags |= instruction.sideEffects.getChangesFlags(); |
| instruction = instruction.next; |
| } |
| assert(blockChangesFlags[id] == null); |
| blockChangesFlags[id] = changesFlags; |
| |
| // Loop headers are part of their loop, so update the loop |
| // changes flags accordingly. |
| if (block.isLoopHeader()) { |
| loopChangesFlags[id] |= changesFlags; |
| } |
| |
| // Propagate loop changes flags upwards. |
| HBasicBlock parentLoopHeader = block.parentLoopHeader; |
| if (parentLoopHeader != null) { |
| loopChangesFlags[parentLoopHeader.id] |= (block.isLoopHeader()) |
| ? loopChangesFlags[id] |
| : changesFlags; |
| } |
| } |
| } |
| |
| int getChangesFlagsForDominatedBlock(HBasicBlock dominator, |
| HBasicBlock dominated) { |
| int changesFlags = 0; |
| List<HBasicBlock> predecessors = dominated.predecessors; |
| for (int i = 0, length = predecessors.length; i < length; i++) { |
| HBasicBlock block = predecessors[i]; |
| int id = block.id; |
| // If the current predecessor block is on the path from the |
| // dominator to the dominated, it must have an id that is in the |
| // range from the dominator to the dominated. |
| if (dominator.id < id && id < dominated.id && !visited.contains(id)) { |
| visited.add(id); |
| changesFlags |= blockChangesFlags[id]; |
| // Loop bodies might not be on the path from dominator to dominated, |
| // but they can invalidate values. |
| changesFlags |= loopChangesFlags[id]; |
| changesFlags |= getChangesFlagsForDominatedBlock(dominator, block); |
| } |
| } |
| return changesFlags; |
| } |
| } |
| |
| // This phase merges equivalent instructions on different paths into |
| // one instruction in a dominator block. It runs through the graph |
| // post dominator order and computes a ValueSet for each block of |
| // instructions that can be moved to a dominator block. These |
| // instructions are the ones that: |
| // 1) can be used for GVN, and |
| // 2) do not use definitions of their own block. |
| // |
| // A basic block looks at its sucessors and finds the intersection of |
| // these computed ValueSet. It moves all instructions of the |
| // intersection into its own list of instructions. |
| class SsaCodeMotion extends HBaseVisitor implements OptimizationPhase { |
| final String name = "SsaCodeMotion"; |
| |
| List<ValueSet> values; |
| |
| void visitGraph(HGraph graph) { |
| values = new List<ValueSet>(graph.blocks.length); |
| for (int i = 0; i < graph.blocks.length; i++) { |
| values[graph.blocks[i].id] = new ValueSet(); |
| } |
| visitPostDominatorTree(graph); |
| } |
| |
| void visitBasicBlock(HBasicBlock block) { |
| List<HBasicBlock> successors = block.successors; |
| |
| // Phase 1: get the ValueSet of all successors (if there are more than one), |
| // compute the intersection and move the instructions of the intersection |
| // into this block. |
| if (successors.length > 1) { |
| ValueSet instructions = values[successors[0].id]; |
| for (int i = 1; i < successors.length; i++) { |
| ValueSet other = values[successors[i].id]; |
| instructions = instructions.intersection(other); |
| } |
| |
| if (!instructions.isEmpty) { |
| List<HInstruction> list = instructions.toList(); |
| for (HInstruction instruction in list) { |
| // Move the instruction to the current block. |
| instruction.block.detach(instruction); |
| block.moveAtExit(instruction); |
| // Go through all successors and rewrite their instruction |
| // to the shared one. |
| for (final successor in successors) { |
| HInstruction toRewrite = values[successor.id].lookup(instruction); |
| if (toRewrite != instruction) { |
| successor.rewriteWithBetterUser(toRewrite, instruction); |
| successor.remove(toRewrite); |
| } |
| } |
| } |
| } |
| } |
| |
| // Don't try to merge instructions to a dominator if we have |
| // multiple predecessors. |
| if (block.predecessors.length != 1) return; |
| |
| // Phase 2: Go through all instructions of this block and find |
| // which instructions can be moved to a dominator block. |
| ValueSet set_ = values[block.id]; |
| HInstruction instruction = block.first; |
| int flags = 0; |
| while (instruction != null) { |
| int dependsFlags = SideEffects.computeDependsOnFlags(flags); |
| flags |= instruction.sideEffects.getChangesFlags(); |
| |
| HInstruction current = instruction; |
| instruction = instruction.next; |
| |
| // TODO(ngeoffray): this check is needed because we currently do |
| // not have flags to express 'Gvn'able', but not movable. |
| if (current is HCheck) continue; |
| if (!current.useGvn()) continue; |
| if (current.sideEffects.dependsOn(dependsFlags)) continue; |
| |
| bool canBeMoved = true; |
| for (final HInstruction input in current.inputs) { |
| if (input.block == block) { |
| canBeMoved = false; |
| break; |
| } |
| } |
| if (!canBeMoved) continue; |
| |
| // This is safe because we are running after GVN. |
| // TODO(ngeoffray): ensure GVN has been run. |
| set_.add(current); |
| } |
| } |
| } |
| |
| class SsaTypeConversionInserter extends HBaseVisitor |
| implements OptimizationPhase { |
| final String name = "SsaTypeconversionInserter"; |
| final Compiler compiler; |
| |
| SsaTypeConversionInserter(this.compiler); |
| |
| void visitGraph(HGraph graph) { |
| visitDominatorTree(graph); |
| } |
| |
| |
| // Update users of [input] that are dominated by [:dominator.first:] |
| // to use [newInput] instead. |
| void changeUsesDominatedBy(HBasicBlock dominator, |
| HInstruction input, |
| HType convertedType) { |
| Set<HInstruction> dominatedUsers = input.dominatedUsers(dominator.first); |
| if (dominatedUsers.isEmpty) return; |
| |
| HTypeConversion newInput = new HTypeConversion( |
| null, HTypeConversion.NO_CHECK, convertedType, input); |
| dominator.addBefore(dominator.first, newInput); |
| dominatedUsers.forEach((HInstruction user) { |
| user.changeUse(input, newInput); |
| }); |
| } |
| |
| void visitIs(HIs instruction) { |
| DartType type = instruction.typeExpression; |
| Element element = type.element; |
| if (!instruction.isRawCheck) { |
| return; |
| } else if (element.isTypedef()) { |
| return; |
| } |
| |
| List<HInstruction> ifUsers = <HInstruction>[]; |
| List<HInstruction> notIfUsers = <HInstruction>[]; |
| for (HInstruction user in instruction.usedBy) { |
| if (user is HIf) { |
| ifUsers.add(user); |
| } else if (user is HNot) { |
| for (HInstruction notUser in user.usedBy) { |
| if (notUser is HIf) notIfUsers.add(notUser); |
| } |
| } |
| } |
| |
| if (ifUsers.isEmpty && notIfUsers.isEmpty) return; |
| |
| HType convertedType = new HType.nonNullSubtype(type, compiler); |
| HInstruction input = instruction.expression; |
| for (HIf ifUser in ifUsers) { |
| changeUsesDominatedBy(ifUser.thenBlock, input, convertedType); |
| // TODO(ngeoffray): Also change uses for the else block on a HType |
| // that knows it is not of a specific Type. |
| } |
| |
| for (HIf ifUser in notIfUsers) { |
| changeUsesDominatedBy(ifUser.elseBlock, input, convertedType); |
| // TODO(ngeoffray): Also change uses for the then block on a HType |
| // that knows it is not of a specific Type. |
| } |
| } |
| } |
| |
| |
| // Analyze the constructors to see if some fields will always have a specific |
| // type after construction. If this is the case we can ignore the type given |
| // by the field initializer. This is especially useful when the field |
| // initializer is initializing the field to null. |
| class SsaConstructionFieldTypes |
| extends HBaseVisitor implements OptimizationPhase { |
| final JavaScriptBackend backend; |
| final CodegenWorkItem work; |
| final String name = "SsaConstructionFieldTypes"; |
| final Set<HInstruction> thisUsers; |
| final Set<Element> allSetters; |
| final Map<HBasicBlock, Map<Element, HType>> blockFieldSetters; |
| bool thisExposed = false; |
| HGraph currentGraph; |
| Map<Element, HType> currentFieldSetters; |
| |
| SsaConstructionFieldTypes(this.backend, this.work) |
| : thisUsers = new Set<HInstruction>(), |
| allSetters = new Set<Element>(), |
| blockFieldSetters = new Map<HBasicBlock, Map<Element, HType>>(); |
| |
| void visitGraph(HGraph graph) { |
| currentGraph = graph; |
| if (!work.element.isGenerativeConstructorBody() && |
| !work.element.isGenerativeConstructor()) return; |
| visitDominatorTree(graph); |
| if (work.element.isGenerativeConstructor()) { |
| backend.registerConstructor(work.element); |
| } |
| } |
| |
| visitBasicBlock(HBasicBlock block) { |
| if (block.predecessors.length == 0) { |
| // Create a new empty map for the first block. |
| currentFieldSetters = new Map<Element, HType>(); |
| } else { |
| // Build a map which intersects the fields from all predecessors. For |
| // each field in this intersection it unions the types. |
| currentFieldSetters = |
| new Map.from(blockFieldSetters[block.predecessors[0]]); |
| // Loop headers are the only nodes with back edges. |
| if (!block.isLoopHeader()) { |
| for (int i = 1; i < block.predecessors.length; i++) { |
| Map<Element, HType> predecessorsFieldSetters = |
| blockFieldSetters[block.predecessors[i]]; |
| Map<Element, HType> newFieldSetters = new Map<Element, HType>(); |
| predecessorsFieldSetters.forEach((Element element, HType type) { |
| HType currentType = currentFieldSetters[element]; |
| if (currentType != null) { |
| newFieldSetters[element] = |
| currentType.union(type, backend.compiler); |
| } |
| }); |
| currentFieldSetters = newFieldSetters; |
| } |
| } else { |
| assert(block.predecessors.length <= 2); |
| } |
| } |
| block.forEachPhi((HPhi phi) => phi.accept(this)); |
| block.forEachInstruction( |
| (HInstruction instruction) => instruction.accept(this)); |
| assert(currentFieldSetters != null); |
| blockFieldSetters[block] = currentFieldSetters; |
| } |
| |
| visitInstruction(HInstruction instruction) { |
| // All instructions not explicitly handled below will flag the this |
| // exposure if using this. |
| thisExposed = thisExposed || thisUsers.contains(instruction); |
| } |
| |
| visitPhi(HPhi phi) { |
| if (thisUsers.contains(phi)) { |
| thisUsers.addAll(phi.usedBy); |
| } |
| } |
| |
| visitThis(HThis instruction) { |
| // Collect all users of this in a set to make the this exposed check simple |
| // and cheap. |
| thisUsers.addAll(instruction.usedBy); |
| } |
| |
| visitFieldGet(HInstruction _) { |
| // The field get instruction is allowed to use this. |
| } |
| |
| visitForeignNew(HForeignNew node) { |
| if (!work.element.isGenerativeConstructor()) return; |
| // Check if this is the new object allocated by this generative |
| // constructor. Inlining might add other [HForeignNew] |
| // instructions in the graph. |
| if (!node.usedBy.any((user) => user is HReturn)) return; |
| // The HForeignNew instruction is used in the generative constructor to |
| // initialize all fields in newly created objects. The fields are |
| // initialized to the value present in the initializer list or set to null |
| // if not otherwise initialized. |
| // Here we handle members in superclasses as well, as the handling of |
| // the generative constructor bodies will ensure, that the initializer |
| // type will not be used if the field is in any of these. |
| int j = 0; |
| node.element.forEachInstanceField( |
| (ClassElement enclosingClass, Element element) { |
| backend.registerFieldInitializer( |
| element, node.inputs[j].instructionType); |
| j++; |
| }, |
| includeSuperAndInjectedMembers: true); |
| } |
| |
| visitFieldSet(HFieldSet node) { |
| Element field = node.element; |
| HInstruction value = node.value; |
| HType type = value.instructionType; |
| // [HFieldSet] is also used for variables in try/catch. |
| if (field.isField()) allSetters.add(field); |
| // Don't handle fields defined in superclasses. Given that the field is |
| // always added to the [allSetters] set, setting a field defined in a |
| // superclass will get an inferred type of UNKNOWN. |
| if (work.element.getEnclosingClass() == field.getEnclosingClass()) { |
| currentFieldSetters[field] = type; |
| } |
| } |
| |
| visitExit(HExit node) { |
| // If this has been exposed then we cannot say anything about types after |
| // construction. |
| if (!thisExposed) { |
| // Register the known field types. |
| currentFieldSetters.forEach((Element element, HType type) { |
| if (type.isUnknown()) return; |
| backend.registerFieldConstructor(element, type); |
| allSetters.remove(element); |
| }); |
| } |
| |
| // For other fields having setters in the generative constructor body, set |
| // the type to UNKNOWN to avoid relying on the type set in the initializer |
| // list. |
| allSetters.forEach((Element element) { |
| backend.registerFieldConstructor(element, HType.UNKNOWN); |
| }); |
| } |
| } |
