| // 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 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 addDependentInstructionsToWorkList(HInstruction instruction) {} |
| |
| void addToWorkList(HInstruction instruction) { |
| final int id = instruction.id; |
| |
| if (!workmap.containsKey(id)) { |
| worklist.add(id); |
| workmap[id] = instruction; |
| } |
| } |
| |
| HType visitInvokeDynamic(HInvokeDynamic instruction) { |
| return instruction.specializer.computeTypeFromInputTypes( |
| instruction, compiler); |
| } |
| |
| 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; |
| } |
| |
| 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.rawType, 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 righ error in checked mode. |
| if (compiler.enableTypeAssertions) return false; |
| HInstruction left = instruction.inputs[1]; |
| HType receiverType = left.instructionType; |
| |
| // A [HTypeGuard] holds the speculated type when it is being |
| // inserted, so we go find the real receiver type. |
| if (left is HTypeGuard) { |
| var guard = left; |
| while (guard is HTypeGuard && !guard.isEnabled) { |
| guard = guard.checkedInput; |
| } |
| receiverType = guard.instructionType; |
| } |
| HInstruction right = instruction.inputs[2]; |
| Selector selector = instruction.selector; |
| if (selector.isOperator() && receiverType.isNumber()) { |
| if (right.isNumber()) return false; |
| // 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, |
| HType.NUMBER, |
| HTypeConversion.ARGUMENT_TYPE_CHECK); |
| return true; |
| } |
| return false; |
| } |
| |
| void processPendingOptimizations() { |
| pendingOptimizations.forEach((instruction, action) => action()); |
| pendingOptimizations.clear(); |
| } |
| } |
| |
| class SsaNonSpeculativeTypePropagator extends SsaTypePropagator { |
| final String name = 'non speculative type propagator'; |
| DesiredTypeVisitor desiredTypeVisitor; |
| SsaNonSpeculativeTypePropagator(Compiler compiler) : super(compiler); |
| |
| void addDependentInstructionsToWorkList(HInstruction instruction) { |
| for (int i = 0, length = instruction.usedBy.length; i < length; i++) { |
| // The non-speculative 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 != const SourceString('==')) { |
| if (checkReceiver(instruction)) { |
| addAllUsersBut(instruction, instruction.inputs[1]); |
| } |
| if (!selector.isUnaryOperator() && checkArgument(instruction)) { |
| addAllUsersBut(instruction, instruction.inputs[2]); |
| } |
| } |
| }); |
| } |
| return super.visitInvokeDynamic(instruction); |
| } |
| } |
| |
| /** |
| * Visitor whose methods return the desired type for the input of an |
| * instruction. |
| */ |
| class DesiredTypeVisitor extends HBaseVisitor { |
| final Compiler compiler; |
| final SsaTypePropagator propagator; |
| HInstruction input; |
| |
| DesiredTypeVisitor(this.compiler, this.propagator); |
| |
| HType visitInstruction(HInstruction instruction) { |
| return HType.UNKNOWN; |
| } |
| |
| HType visitCheck(HCheck check) { |
| // If the desired type of the input is already a number, we want |
| // to specialize it to an integer. |
| if (input == check.checkedInput |
| && check.isInteger() |
| && check.checkedInput.isNumberOrNull()) { |
| return HType.INTEGER; |
| } |
| return HType.UNKNOWN; |
| } |
| |
| HType visitTypeConversion(HTypeConversion check) { |
| // The following checks are inserted by our optimizers, so we |
| // want to optimize them even more. |
| if (check.isArgumentTypeCheck || check.isReceiverTypeCheck) { |
| return visitCheck(check); |
| } |
| return HType.UNKNOWN; |
| } |
| |
| HType visitInvokeDynamic(HInvokeDynamic instruction) { |
| return instruction.specializer.computeDesiredTypeForInput( |
| instruction, input, compiler); |
| } |
| |
| HType visitNot(HNot instruction) { |
| return HType.BOOLEAN; |
| } |
| |
| HType visitPhi(HPhi phi) { |
| // Best case scenario for a phi is, when all inputs have the same type. If |
| // there is no desired outgoing type we therefore try to unify the input |
| // types (which is basically the [likelyType]). |
| HType propagatedType = phi.instructionType; |
| |
| // If the incoming type of a phi is an integer, we don't want to |
| // be too restrictive for the back edge and desire an integer |
| // too. Therefore we only return integer if the phi is used by a |
| // bounds check, which includes an integer check. |
| if (propagatedType.isInteger()) { |
| if (phi.usedBy.any((user) => user is HBoundsCheck && user.index == phi)) { |
| return propagatedType; |
| } |
| return HType.NUMBER; |
| } |
| if (propagatedType.isUnknown()) return computeLikelyType(phi); |
| // When the desired outgoing type is conflicting we don't need to give any |
| // requirements on the inputs. |
| if (propagatedType.isConflicting()) return HType.UNKNOWN; |
| // Otherwise the input type must match the desired outgoing type. |
| return propagatedType; |
| } |
| |
| HType computeLikelyType(HPhi phi) { |
| HType agreedType = propagator.computeInputsType(phi, true); |
| if (agreedType.isConflicting()) return HType.UNKNOWN; |
| // Don't be too restrictive. If the agreed type is integer or double just |
| // say that the likely type is number. If more is expected the type will be |
| // propagated back. |
| if (agreedType.isNumber()) return HType.NUMBER; |
| return agreedType; |
| } |
| |
| HType visitInterceptor(HInterceptor instruction) { |
| if (instruction.interceptedClasses.length != 1) return HType.UNKNOWN; |
| // If the only class being intercepted is of type number, we |
| // make this interceptor call say it wants that class as input. |
| Element interceptor = instruction.interceptedClasses.toList()[0]; |
| JavaScriptBackend backend = compiler.backend; |
| if (interceptor == backend.jsNumberClass) { |
| return HType.NUMBER; |
| } else if (interceptor == backend.jsIntClass) { |
| return HType.INTEGER; |
| } else if (interceptor == backend.jsDoubleClass) { |
| return HType.DOUBLE; |
| } |
| return HType.UNKNOWN; |
| } |
| |
| HType computeDesiredTypeForInput(HInstruction user, HInstruction input) { |
| this.input = input; |
| HType desired = user.accept(this); |
| this.input = null; |
| return desired; |
| } |
| } |
| |
| class SsaSpeculativeTypePropagator extends SsaTypePropagator { |
| final String name = 'speculative type propagator'; |
| DesiredTypeVisitor desiredTypeVisitor; |
| final Map<HInstruction, HType> savedTypes; |
| SsaSpeculativeTypePropagator(Compiler compiler, this.savedTypes) |
| : super(compiler) { |
| desiredTypeVisitor = new DesiredTypeVisitor(compiler, this); |
| } |
| |
| void addDependentInstructionsToWorkList(HInstruction instruction) { |
| // The speculative type propagator propagates types forward and backward. |
| // Not only do we need to add the users of the [instruction] to the list. |
| // We also need to add the inputs fo the [instruction], since they might |
| // want to propagate the desired outgoing type. |
| for (int i = 0, length = instruction.usedBy.length; i < length; i++) { |
| addToWorkList(instruction.usedBy[i]); |
| } |
| for (int i = 0, length = instruction.inputs.length; i < length; i++) { |
| addToWorkList(instruction.inputs[i]); |
| } |
| } |
| |
| HType computeDesiredType(HInstruction instruction) { |
| HType desiredType = instruction.instructionType; |
| for (final user in instruction.usedBy) { |
| HType userDesiredType = desiredTypeVisitor.computeDesiredTypeForInput( |
| user, instruction); |
| desiredType = desiredType.intersection(userDesiredType, compiler); |
| // No need to continue if two users disagree on the type. |
| if (desiredType.isConflicting()) break; |
| } |
| return desiredType; |
| } |
| |
| bool hasBeenSpeculativelyOptimized(HInstruction instruction) { |
| return savedTypes.containsKey(instruction); |
| } |
| |
| HType computeType(HInstruction instruction) { |
| // Once we are in a conflicting state don't update the type anymore. |
| HType oldType = instruction.instructionType; |
| if (oldType.isConflicting()) return oldType; |
| |
| HType newType = super.computeType(instruction); |
| if (oldType != newType && !hasBeenSpeculativelyOptimized(instruction)) { |
| savedTypes[instruction] = oldType; |
| } |
| // [computeDesiredType] goes to all usedBys and lets them compute their |
| // desired type. By setting the [newType] here we give them more context to |
| // work with. |
| instruction.instructionType = newType; |
| HType desiredType = computeDesiredType(instruction); |
| // If the desired type is conflicting just return the computed type. |
| if (desiredType.isConflicting()) return newType; |
| if (desiredType.isUnknown() && hasBeenSpeculativelyOptimized(instruction)) { |
| // If we ever change our decision for a desired type to unknown, |
| // we stop the computation on this instruction. |
| return HType.CONFLICTING; |
| } |
| // TODO(ngeoffray): Allow speculative optimizations on |
| // non-primitive types? |
| if (!desiredType.isPrimitive(compiler)) return newType; |
| desiredType = newType.intersection(desiredType, compiler); |
| if (desiredType != newType && !hasBeenSpeculativelyOptimized(instruction)) { |
| savedTypes[instruction] = oldType; |
| } |
| return desiredType; |
| } |
| } |