| // 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; |
| String get name => 'type propagator'; |
| |
| SsaTypePropagator(this.compiler); |
| |
| // Compute the (shared) type of the inputs if any. If all inputs |
| // have the same known type return it. If any two inputs have |
| // different known types, we'll return a conflict -- otherwise we'll |
| // simply return an unknown type. |
| HType computeInputsType(HPhi phi, bool ignoreUnknowns) { |
| HType candidateType = HType.CONFLICTING; |
| for (int i = 0, length = phi.inputs.length; i < length; i++) { |
| HType inputType = phi.inputs[i].instructionType; |
| if (inputType.isConflicting()) return HType.CONFLICTING; |
| if (ignoreUnknowns && inputType.isUnknown()) continue; |
| // Phis need to combine the incoming types using the union operation. |
| // For example, if one incoming edge has type integer and the other has |
| // type double, then the phi is either an integer or double and thus has |
| // type number. |
| candidateType = candidateType.union(inputType, compiler); |
| if (candidateType.isUnknown()) return HType.UNKNOWN; |
| } |
| return candidateType; |
| } |
| |
| HType 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. |
| HType oldType = instruction.instructionType; |
| HType 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; |
| } |
| } |
| |
| HType visitBinaryArithmetic(HBinaryArithmetic instruction) { |
| HInstruction left = instruction.left; |
| HInstruction right = instruction.right; |
| if (left.isInteger() && right.isInteger()) return HType.INTEGER; |
| if (left.isDouble()) return HType.DOUBLE; |
| return HType.NUMBER; |
| } |
| |
| HType visitNegate(HNegate instruction) { |
| return instruction.operand.instructionType; |
| } |
| |
| HType visitInstruction(HInstruction instruction) { |
| assert(instruction.instructionType != null); |
| return instruction.instructionType; |
| } |
| |
| HType visitPhi(HPhi phi) { |
| HType inputsType = computeInputsType(phi, false); |
| if (inputsType.isConflicting()) return HType.UNKNOWN; |
| return inputsType; |
| } |
| |
| HType visitTypeConversion(HTypeConversion instruction) { |
| HType inputType = instruction.checkedInput.instructionType; |
| HType 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.isNumber() |
| && !checkedType.isDouble() |
| && inputType.isIntegerOrNull()) { |
| instruction.checkedType = HType.INTEGER; |
| } else if (checkedType.isInteger() && !inputType.isIntegerOrNull()) { |
| instruction.checkedType = HType.NUMBER; |
| } |
| } |
| |
| HType outputType = checkedType.intersection(inputType, compiler); |
| if (outputType.isConflicting()) { |
| // 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 HType system. |
| if (inputType.isIntegerOrNull() && checkedType.isDoubleOrNull()) { |
| if (inputType.canBeNull() && checkedType.canBeNull()) { |
| outputType = HType.DOUBLE_OR_NULL; |
| } else { |
| outputType = HType.DOUBLE; |
| } |
| } |
| } |
| return outputType; |
| } |
| |
| HType visitTypeKnown(HTypeKnown instruction) { |
| HInstruction input = instruction.checkedInput; |
| return instruction.knownType.intersection(input.instructionType, compiler); |
| } |
| |
| void convertInput(HInvokeDynamic instruction, |
| HInstruction input, |
| HType 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, |
| HType 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.isInteger()) { |
| // 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.instructionType.isIntegerOrNull(); |
| } |
| 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) { |
| HInstruction receiver = instruction.inputs[1]; |
| if (receiver.isNumber()) return false; |
| if (receiver.isNumberOrNull()) { |
| convertInput(instruction, |
| receiver, |
| receiver.instructionType.nonNullable(compiler), |
| 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.getEnclosingClass(); |
| HType type = new HType.nonNullSubclass(cls, compiler); |
| // TODO(ngeoffray): We currently only optimize on primitive |
| // types. |
| if (!type.isPrimitive(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]; |
| HType receiverType = left.instructionType; |
| |
| HInstruction right = instruction.inputs[2]; |
| Selector selector = instruction.selector; |
| if (selector.isOperator() && receiverType.isNumber()) { |
| if (right.isNumber()) return false; |
| HType type = right.isIntegerOrNull() ? HType.INTEGER : HType.NUMBER; |
| // 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); |
| }); |
| } |
| |
| HType 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]); |
| } |
| } |
| }); |
| } |
| return instruction.specializer.computeTypeFromInputTypes( |
| instruction, compiler); |
| } |
| } |