| // 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; |
| |
| class SsaTypePropagator extends HBaseVisitor implements OptimizationPhase { |
| final Map<int, HInstruction> workmap = new Map<int, HInstruction>(); |
| final List<int> worklist = new List<int>(); |
| final Map<HInstruction, Function> pendingOptimizations = |
| new Map<HInstruction, Function>(); |
| |
| final Compiler compiler; |
| JavaScriptBackend get backend => compiler.backend; |
| String get name => 'type propagator'; |
| |
| SsaTypePropagator(this.compiler); |
| |
| TypeMask computeType(HInstruction instruction) { |
| return instruction.accept(this); |
| } |
| |
| // Re-compute and update the type of the instruction. Returns |
| // whether or not the type was changed. |
| bool updateType(HInstruction instruction) { |
| // Compute old and new types. |
| TypeMask oldType = instruction.instructionType; |
| TypeMask newType = computeType(instruction); |
| assert(newType != null); |
| // We unconditionally replace the propagated type with the new type. The |
| // computeType must make sure that we eventually reach a stable state. |
| instruction.instructionType = newType; |
| return oldType != newType; |
| } |
| |
| void visitGraph(HGraph graph) { |
| visitDominatorTree(graph); |
| processWorklist(); |
| } |
| |
| visitBasicBlock(HBasicBlock block) { |
| if (block.isLoopHeader()) { |
| block.forEachPhi((HPhi phi) { |
| // Set the initial type for the phi. We're not using the type |
| // the phi thinks it has because new optimizations may imply |
| // changing it. |
| // In theory we would need to mark |
| // the type of all other incoming edges as "unitialized" and take this |
| // into account when doing the propagation inside the phis. Just |
| // setting the propagated type is however easier. |
| phi.instructionType = phi.inputs[0].instructionType; |
| addToWorkList(phi); |
| }); |
| } else { |
| block.forEachPhi((HPhi phi) { |
| if (updateType(phi)) { |
| addDependentInstructionsToWorkList(phi); |
| } |
| }); |
| } |
| |
| HInstruction instruction = block.first; |
| while (instruction != null) { |
| if (updateType(instruction)) { |
| addDependentInstructionsToWorkList(instruction); |
| } |
| instruction = instruction.next; |
| } |
| } |
| |
| void processWorklist() { |
| do { |
| while (!worklist.isEmpty) { |
| int id = worklist.removeLast(); |
| HInstruction instruction = workmap[id]; |
| assert(instruction != null); |
| workmap.remove(id); |
| if (updateType(instruction)) { |
| addDependentInstructionsToWorkList(instruction); |
| } |
| } |
| // While processing the optimizable arithmetic instructions, we |
| // may discover better type information for dominated users of |
| // replaced operands, so we may need to take another stab at |
| // emptying the worklist afterwards. |
| processPendingOptimizations(); |
| } while (!worklist.isEmpty); |
| } |
| |
| |
| void addToWorkList(HInstruction instruction) { |
| final int id = instruction.id; |
| |
| if (!workmap.containsKey(id)) { |
| worklist.add(id); |
| workmap[id] = instruction; |
| } |
| } |
| |
| TypeMask visitBinaryArithmetic(HBinaryArithmetic instruction) { |
| HInstruction left = instruction.left; |
| HInstruction right = instruction.right; |
| if (left.isInteger(compiler) && right.isInteger(compiler)) { |
| return backend.intType; |
| } |
| if (left.isDouble(compiler)) return backend.doubleType; |
| return backend.numType; |
| } |
| |
| TypeMask checkPositiveInteger(HBinaryArithmetic instruction) { |
| HInstruction left = instruction.left; |
| HInstruction right = instruction.right; |
| if (left.isPositiveInteger(compiler) && right.isPositiveInteger(compiler)) { |
| return backend.positiveIntType; |
| } |
| return visitBinaryArithmetic(instruction); |
| } |
| |
| TypeMask visitMultiply(HMultiply instruction) { |
| return checkPositiveInteger(instruction); |
| } |
| |
| TypeMask visitAdd(HAdd instruction) { |
| return checkPositiveInteger(instruction); |
| } |
| |
| TypeMask visitNegate(HNegate instruction) { |
| HInstruction operand = instruction.operand; |
| // We have integer subclasses that represent ranges, so widen any int |
| // subclass to full integer. |
| if (operand.isInteger(compiler)) return backend.intType; |
| return instruction.operand.instructionType; |
| } |
| |
| TypeMask visitInstruction(HInstruction instruction) { |
| assert(instruction.instructionType != null); |
| return instruction.instructionType; |
| } |
| |
| TypeMask visitPhi(HPhi phi) { |
| TypeMask candidateType = backend.emptyType; |
| for (int i = 0, length = phi.inputs.length; i < length; i++) { |
| TypeMask inputType = phi.inputs[i].instructionType; |
| candidateType = candidateType.union(inputType, compiler); |
| } |
| return candidateType; |
| } |
| |
| TypeMask visitTypeConversion(HTypeConversion instruction) { |
| HInstruction input = instruction.checkedInput; |
| TypeMask inputType = input.instructionType; |
| TypeMask checkedType = instruction.checkedType; |
| if (instruction.isArgumentTypeCheck || instruction.isReceiverTypeCheck) { |
| // We must make sure a type conversion for receiver or argument check |
| // does not try to do an int check, because an int check is not enough. |
| // We only do an int check if the input is integer or null. |
| if (checkedType.containsOnlyNum(compiler) |
| && !checkedType.containsOnlyDouble(compiler) |
| && input.isIntegerOrNull(compiler)) { |
| instruction.checkedType = backend.intType; |
| } else if (checkedType.containsOnlyInt(compiler) |
| && !input.isIntegerOrNull(compiler)) { |
| instruction.checkedType = backend.numType; |
| } |
| } |
| |
| TypeMask outputType = checkedType.intersection(inputType, compiler); |
| if (outputType.isEmpty && !outputType.isNullable) { |
| // Intersection of double and integer conflicts (is empty), but JS numbers |
| // can be both int and double at the same time. For example, the input |
| // can be a literal double '8.0' that is marked as an integer (because 'is |
| // int' will return 'true'). What we really need to do is make the |
| // overlap between int and double values explicit in the TypeMask system. |
| if (inputType.containsOnlyInt(compiler) |
| && checkedType.containsOnlyDouble(compiler)) { |
| if (inputType.isNullable && checkedType.isNullable) { |
| outputType = backend.doubleType.nullable(); |
| } else { |
| outputType = backend.doubleType; |
| } |
| } |
| } |
| return outputType; |
| } |
| |
| TypeMask visitTypeKnown(HTypeKnown instruction) { |
| HInstruction input = instruction.checkedInput; |
| return instruction.knownType.intersection(input.instructionType, compiler); |
| } |
| |
| void convertInput(HInvokeDynamic instruction, |
| HInstruction input, |
| TypeMask type, |
| int kind) { |
| Selector selector = (kind == HTypeConversion.RECEIVER_TYPE_CHECK) |
| ? instruction.selector |
| : null; |
| HTypeConversion converted = new HTypeConversion( |
| null, kind, type, input, selector); |
| instruction.block.addBefore(instruction, converted); |
| input.replaceAllUsersDominatedBy(instruction, converted); |
| } |
| |
| bool isCheckEnoughForNsmOrAe(HInstruction instruction, |
| TypeMask type) { |
| // In some cases, we want the receiver to be an integer, |
| // but that does not mean we will get a NoSuchMethodError |
| // if it's not: the receiver could be a double. |
| if (type.containsOnlyInt(compiler)) { |
| // If the instruction's type is integer or null, the codegen |
| // will emit a null check, which is enough to know if it will |
| // hit a noSuchMethod. |
| return instruction.isIntegerOrNull(compiler); |
| } |
| return true; |
| } |
| |
| // Add a receiver type check when the call can only hit |
| // [noSuchMethod] if the receiver is not of a specific type. |
| // Return true if the receiver type check was added. |
| bool checkReceiver(HInvokeDynamic instruction) { |
| assert(instruction.isInterceptedCall); |
| HInstruction receiver = instruction.inputs[1]; |
| if (receiver.isNumber(compiler)) return false; |
| if (receiver.isNumberOrNull(compiler)) { |
| convertInput(instruction, |
| receiver, |
| receiver.instructionType.nonNullable(), |
| HTypeConversion.RECEIVER_TYPE_CHECK); |
| return true; |
| } else if (instruction.element == null) { |
| Iterable<Element> targets = |
| compiler.world.allFunctions.filter(instruction.selector); |
| if (targets.length == 1) { |
| Element target = targets.first; |
| ClassElement cls = target.enclosingClass; |
| TypeMask type = new TypeMask.nonNullSubclass(cls.declaration); |
| // TODO(ngeoffray): We currently only optimize on primitive |
| // types. |
| if (!type.satisfies(backend.jsIndexableClass, compiler) |
| && !type.containsOnlyNum(compiler) |
| && !type.containsOnlyBool(compiler)) { |
| return false; |
| } |
| if (!isCheckEnoughForNsmOrAe(receiver, type)) return false; |
| instruction.element = target; |
| convertInput(instruction, |
| receiver, |
| type, |
| HTypeConversion.RECEIVER_TYPE_CHECK); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // Add an argument type check if the argument is not of a type |
| // expected by the call. |
| // Return true if the argument type check was added. |
| bool checkArgument(HInvokeDynamic instruction) { |
| // We want the right error in checked mode. |
| if (compiler.enableTypeAssertions) return false; |
| HInstruction left = instruction.inputs[1]; |
| HInstruction right = instruction.inputs[2]; |
| |
| Selector selector = instruction.selector; |
| if (selector.isOperator && left.isNumber(compiler)) { |
| if (right.isNumber(compiler)) return false; |
| TypeMask type = right.isIntegerOrNull(compiler) |
| ? right.instructionType.nonNullable() |
| : backend.numType; |
| // TODO(ngeoffray): Some number operations don't have a builtin |
| // variant and will do the check in their method anyway. We |
| // still add a check because it allows to GVN these operations, |
| // but we should find a better way. |
| convertInput(instruction, |
| right, |
| type, |
| HTypeConversion.ARGUMENT_TYPE_CHECK); |
| return true; |
| } |
| return false; |
| } |
| |
| void processPendingOptimizations() { |
| pendingOptimizations.forEach((instruction, action) => action()); |
| pendingOptimizations.clear(); |
| } |
| |
| void addDependentInstructionsToWorkList(HInstruction instruction) { |
| for (int i = 0, length = instruction.usedBy.length; i < length; i++) { |
| // The type propagator only propagates types forward. We |
| // thus only need to add the users of the [instruction] to the list. |
| addToWorkList(instruction.usedBy[i]); |
| } |
| } |
| |
| void addAllUsersBut(HInvokeDynamic invoke, HInstruction instruction) { |
| instruction.usedBy.forEach((HInstruction user) { |
| if (user != invoke) addToWorkList(user); |
| }); |
| } |
| |
| TypeMask visitInvokeDynamic(HInvokeDynamic instruction) { |
| if (instruction.isInterceptedCall) { |
| // We cannot do the following optimization now, because we have |
| // to wait for the type propagation to be stable. The receiver |
| // of [instruction] might move from number to dynamic. |
| pendingOptimizations.putIfAbsent(instruction, () => () { |
| Selector selector = instruction.selector; |
| if (selector.isOperator && selector.name != '==') { |
| if (checkReceiver(instruction)) { |
| addAllUsersBut(instruction, instruction.inputs[1]); |
| } |
| if (!selector.isUnaryOperator && checkArgument(instruction)) { |
| addAllUsersBut(instruction, instruction.inputs[2]); |
| } |
| } |
| }); |
| } |
| |
| HInstruction receiver = instruction.getDartReceiver(compiler); |
| TypeMask receiverType = receiver.instructionType; |
| Selector selector = new TypedSelector(receiverType, instruction.selector, |
| compiler); |
| instruction.selector = selector; |
| |
| // Try to specialize the receiver after this call. |
| if (receiver.dominatedUsers(instruction).length != 1 |
| && !selector.isClosureCall) { |
| TypeMask newType = compiler.world.allFunctions.receiverType(selector); |
| newType = newType.intersection(receiverType, compiler); |
| var next = instruction.next; |
| if (next is HTypeKnown && next.checkedInput == receiver) { |
| // We already have refined [receiver]. We still update the |
| // type of the [HTypeKnown] instruction because it may have |
| // been refined with a correct type at the time, but |
| // incorrect now. |
| if (next.instructionType != newType) { |
| next.knownType = next.instructionType = newType; |
| addDependentInstructionsToWorkList(next); |
| } |
| } else if (newType != receiverType) { |
| // Insert a refinement node after the call and update all |
| // users dominated by the call to use that node instead of |
| // [receiver]. |
| HTypeKnown converted = |
| new HTypeKnown.witnessed(newType, receiver, instruction); |
| instruction.block.addBefore(instruction.next, converted); |
| receiver.replaceAllUsersDominatedBy(converted.next, converted); |
| addDependentInstructionsToWorkList(converted); |
| } |
| } |
| |
| return instruction.specializer.computeTypeFromInputTypes( |
| instruction, compiler); |
| } |
| } |