sdk/lib/_internal/compiler/implementation/ssa/interceptor_simplifier.dart - sdk.git - Git at Google

 // Copyright (c) 2013, 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;

 /**
  * This phase simplifies interceptors in multiple ways:
  *
  * 1) If the interceptor is for an object whose type is known, it
  * tries to use a constant interceptor instead.
  *
  * 2) It specializes interceptors based on the selectors it is being
  * called with.
  *
  * 3) If we know the object is not intercepted, we just use it
  * instead.
  *
  * 4) It replaces all interceptors that are used only once with
  * one-shot interceptors. It saves code size and makes the receiver of
  * an intercepted call a candidate for being generated at use site.
  *
  */
 class SsaSimplifyInterceptors extends HBaseVisitor
     implements OptimizationPhase {
   final String name = "SsaSimplifyInterceptors";
   final ConstantSystem constantSystem;
   final Compiler compiler;
   final CodegenWorkItem work;
   HGraph graph;

   SsaSimplifyInterceptors(this.compiler, this.constantSystem, this.work);

   void visitGraph(HGraph graph) {
     this.graph = graph;
     visitDominatorTree(graph);
   }

   void visitBasicBlock(HBasicBlock node) {
     currentBlock = node;

     HInstruction instruction = node.first;
     while (instruction != null) {
       bool shouldRemove = instruction.accept(this);
       HInstruction next = instruction.next;
       if (shouldRemove) {
         instruction.block.remove(instruction);
       }
       instruction = next;
     }
   }

   bool visitInstruction(HInstruction instruction) => false;

   bool visitInvoke(HInvoke invoke) {
     if (!invoke.isInterceptedCall) return false;
     var interceptor = invoke.inputs[0];
     if (interceptor is! HInterceptor) return false;
     HInstruction constant = tryComputeConstantInterceptor(
         invoke.inputs[1], interceptor.interceptedClasses);
     if (constant != null) {
       invoke.changeUse(interceptor, constant);
     }
     return false;
   }

   bool canUseSelfForInterceptor(HInstruction receiver,
                                 Set<ClassElement> interceptedClasses) {
     JavaScriptBackend backend = compiler.backend;
     if (receiver.canBePrimitive(compiler)) {
       // Primitives always need interceptors.
       return false;
     }
     if (receiver.canBeNull() &&
         interceptedClasses.contains(backend.jsNullClass)) {
       // Need the JSNull interceptor.
       return false;
     }

     // All intercepted classes extend `Interceptor`, so if the receiver can't be
     // a class extending `Interceptor` then it can be called directly.
     return new TypeMask.nonNullSubclass(backend.jsInterceptorClass)
         .intersection(receiver.instructionType, compiler)
         .isEmpty;
   }

   HInstruction tryComputeConstantInterceptor(
       HInstruction input,
       Set<ClassElement> interceptedClasses) {
     if (input == graph.explicitReceiverParameter) {
       // If `explicitReceiverParameter` is set it means the current method is an
       // interceptor method, and `this` is the interceptor.  The caller just did
       // `getInterceptor(foo).currentMethod(foo)` to enter the current method.
       return graph.thisInstruction;
     }

     ClassElement constantInterceptor;
     JavaScriptBackend backend = compiler.backend;
     if (input.canBeNull()) {
       if (input.isNull()) {
         constantInterceptor = backend.jsNullClass;
       }
     } else if (input.isInteger(compiler)) {
       constantInterceptor = backend.jsIntClass;
     } else if (input.isDouble(compiler)) {
       constantInterceptor = backend.jsDoubleClass;
     } else if (input.isBoolean(compiler)) {
       constantInterceptor = backend.jsBoolClass;
     } else if (input.isString(compiler)) {
       constantInterceptor = backend.jsStringClass;
     } else if (input.isArray(compiler)) {
       constantInterceptor = backend.jsArrayClass;
     } else if (input.isNumber(compiler) &&
         !interceptedClasses.contains(backend.jsIntClass) &&
         !interceptedClasses.contains(backend.jsDoubleClass)) {
       // If the method being intercepted is not defined in [int] or [double] we
       // can safely use the number interceptor.  This is because none of the
       // [int] or [double] methods are called from a method defined on [num].
       constantInterceptor = backend.jsNumberClass;
     } else {
       // Try to find constant interceptor for a native class.  If the receiver
       // is constrained to a leaf native class, we can use the class's
       // interceptor directly.

       // TODO(sra): Key DOM classes like Node, Element and Event are not leaf
       // classes.  When the receiver type is not a leaf class, we might still be
       // able to use the receiver class as a constant interceptor.  It is
       // usually the case that methods defined on a non-leaf class don't test
       // for a subclass or call methods defined on a subclass.  Provided the
       // code is completely insensitive to the specific instance subclasses, we
       // can use the non-leaf class directly.
       ClassElement element = input.instructionType.singleClass(compiler);
       if (element != null && element.isNative()) {
         constantInterceptor = element;
       }
     }

     if (constantInterceptor == null) return null;

     // If we just happen to be in an instance method of the constant
     // interceptor, `this` is a shorter alias.
     if (constantInterceptor == work.element.getEnclosingClass() &&
         graph.thisInstruction != null) {
       return graph.thisInstruction;
     }

     Constant constant = new InterceptorConstant(constantInterceptor.thisType);
     return graph.addConstant(constant, compiler);
   }

   HInstruction findDominator(Iterable<HInstruction> instructions) {
     HInstruction result;
     L1: for (HInstruction candidate in instructions) {
       for (HInstruction current in instructions) {
         if (current != candidate && !candidate.dominates(current)) continue L1;
       }
       result = candidate;
       break;
     }
     return result;
   }

   bool visitInterceptor(HInterceptor node) {
     if (node.isConstant()) return false;

     // If the interceptor is used by multiple instructions, specialize
     // it with a set of classes it intercepts.
     Set<ClassElement> interceptedClasses;
     JavaScriptBackend backend = compiler.backend;
     HInstruction dominator = findDominator(node.usedBy);
     // If there is a call that dominates all other uses, we can use just the
     // selector of that instruction.
     if (dominator is HInvokeDynamic &&
         dominator.isCallOnInterceptor(compiler) &&
         node == dominator.receiver) {
       interceptedClasses =
             backend.getInterceptedClassesOn(dominator.selector.name);

       // If we found that we need number, we must still go through all
       // uses to check if they require int, or double.
       if (interceptedClasses.contains(backend.jsNumberClass) &&
           !(interceptedClasses.contains(backend.jsDoubleClass) ||
             interceptedClasses.contains(backend.jsIntClass))) {
         for (HInstruction user in node.usedBy) {
           if (user is! HInvoke) continue;
           Set<ClassElement> intercepted =
               backend.getInterceptedClassesOn(user.selector.name);
           if (intercepted.contains(backend.jsIntClass)) {
             interceptedClasses.add(backend.jsIntClass);
           }
           if (intercepted.contains(backend.jsDoubleClass)) {
             interceptedClasses.add(backend.jsDoubleClass);
           }
         }
       }
     } else {
       interceptedClasses = new Set<ClassElement>();
       for (HInstruction user in node.usedBy) {
         if (user is HInvokeDynamic &&
             user.isCallOnInterceptor(compiler) &&
             node == user.receiver) {
           interceptedClasses.addAll(
               backend.getInterceptedClassesOn(user.selector.name));
         } else {
           // Use a most general interceptor for other instructions, example,
           // is-checks and escaping interceptors.
           interceptedClasses.addAll(backend.interceptedClasses);
           break;
         }
       }
     }

     HInstruction receiver = node.receiver;
     if (canUseSelfForInterceptor(receiver, interceptedClasses)) {
       return rewriteToUseSelfAsInterceptor(node, receiver);
     }

     // Try computing a constant interceptor.
     HInstruction constantInterceptor =
         tryComputeConstantInterceptor(receiver, interceptedClasses);
     if (constantInterceptor != null) {
       node.block.rewrite(node, constantInterceptor);
       return false;
     }

     node.interceptedClasses = interceptedClasses;

     // Try creating a one-shot interceptor.
     if (node.usedBy.length != 1) return false;
     if (node.usedBy[0] is !HInvokeDynamic) return false;

     HInvokeDynamic user = node.usedBy[0];

     // If [node] was loop hoisted, we keep the interceptor.
     if (!user.hasSameLoopHeaderAs(node)) return false;

     // Replace the user with a [HOneShotInterceptor].
     HConstant nullConstant = graph.addConstantNull(compiler);
     List<HInstruction> inputs = new List<HInstruction>.from(user.inputs);
     inputs[0] = nullConstant;
     HOneShotInterceptor interceptor = new HOneShotInterceptor(
         user.selector, inputs, user.instructionType, node.interceptedClasses);
     interceptor.sourcePosition = user.sourcePosition;
     interceptor.sourceElement = user.sourceElement;

     HBasicBlock block = user.block;
     block.addAfter(user, interceptor);
     block.rewrite(user, interceptor);
     block.remove(user);
     return true;
   }

   bool rewriteToUseSelfAsInterceptor(HInterceptor node, HInstruction receiver) {
     node.block.rewrite(node, receiver);
     return false;
   }

   bool visitOneShotInterceptor(HOneShotInterceptor node) {
     HInstruction constant = tryComputeConstantInterceptor(
         node.inputs[1], node.interceptedClasses);

     if (constant == null) return false;

     Selector selector = node.selector;
     HInstruction instruction;
     if (selector.isGetter()) {
       instruction = new HInvokeDynamicGetter(
           selector,
           node.element,
           <HInstruction>[constant, node.inputs[1]],
           node.instructionType);
     } else if (selector.isSetter()) {
       instruction = new HInvokeDynamicSetter(
           selector,
           node.element,
           <HInstruction>[constant, node.inputs[1], node.inputs[2]],
           node.instructionType);
     } else {
       List<HInstruction> inputs = new List<HInstruction>.from(node.inputs);
       inputs[0] = constant;
       instruction = new HInvokeDynamicMethod(
           selector, inputs, node.instructionType, true);
     }

     HBasicBlock block = node.block;
     block.addAfter(node, instruction);
     block.rewrite(node, instruction);
     return true;
   }
 }
	// Copyright (c) 2013, 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;

	/**
	* This phase simplifies interceptors in multiple ways:
	*
	* 1) If the interceptor is for an object whose type is known, it
	* tries to use a constant interceptor instead.
	*
	* 2) It specializes interceptors based on the selectors it is being
	* called with.
	*
	* 3) If we know the object is not intercepted, we just use it
	* instead.
	*
	* 4) It replaces all interceptors that are used only once with
	* one-shot interceptors. It saves code size and makes the receiver of
	* an intercepted call a candidate for being generated at use site.
	*
	*/
	class SsaSimplifyInterceptors extends HBaseVisitor
	implements OptimizationPhase {
	final String name = "SsaSimplifyInterceptors";
	final ConstantSystem constantSystem;
	final Compiler compiler;
	final CodegenWorkItem work;
	HGraph graph;

	SsaSimplifyInterceptors(this.compiler, this.constantSystem, this.work);

	void visitGraph(HGraph graph) {
	this.graph = graph;
	visitDominatorTree(graph);
	}

	void visitBasicBlock(HBasicBlock node) {
	currentBlock = node;

	HInstruction instruction = node.first;
	while (instruction != null) {
	bool shouldRemove = instruction.accept(this);
	HInstruction next = instruction.next;
	if (shouldRemove) {
	instruction.block.remove(instruction);
	}
	instruction = next;
	}
	}

	bool visitInstruction(HInstruction instruction) => false;

	bool visitInvoke(HInvoke invoke) {
	if (!invoke.isInterceptedCall) return false;
	var interceptor = invoke.inputs[0];
	if (interceptor is! HInterceptor) return false;
	HInstruction constant = tryComputeConstantInterceptor(
	invoke.inputs[1], interceptor.interceptedClasses);
	if (constant != null) {
	invoke.changeUse(interceptor, constant);
	}
	return false;
	}

	bool canUseSelfForInterceptor(HInstruction receiver,
	Set<ClassElement> interceptedClasses) {
	JavaScriptBackend backend = compiler.backend;
	if (receiver.canBePrimitive(compiler)) {
	// Primitives always need interceptors.
	return false;
	}
	if (receiver.canBeNull() &&
	interceptedClasses.contains(backend.jsNullClass)) {
	// Need the JSNull interceptor.
	return false;
	}

	// All intercepted classes extend `Interceptor`, so if the receiver can't be
	// a class extending `Interceptor` then it can be called directly.
	return new TypeMask.nonNullSubclass(backend.jsInterceptorClass)
	.intersection(receiver.instructionType, compiler)
	.isEmpty;
	}

	HInstruction tryComputeConstantInterceptor(
	HInstruction input,
	Set<ClassElement> interceptedClasses) {
	if (input == graph.explicitReceiverParameter) {
	// If `explicitReceiverParameter` is set it means the current method is an
	// interceptor method, and `this` is the interceptor. The caller just did
	// `getInterceptor(foo).currentMethod(foo)` to enter the current method.
	return graph.thisInstruction;
	}

	ClassElement constantInterceptor;
	JavaScriptBackend backend = compiler.backend;
	if (input.canBeNull()) {
	if (input.isNull()) {
	constantInterceptor = backend.jsNullClass;
	}
	} else if (input.isInteger(compiler)) {
	constantInterceptor = backend.jsIntClass;
	} else if (input.isDouble(compiler)) {
	constantInterceptor = backend.jsDoubleClass;
	} else if (input.isBoolean(compiler)) {
	constantInterceptor = backend.jsBoolClass;
	} else if (input.isString(compiler)) {
	constantInterceptor = backend.jsStringClass;
	} else if (input.isArray(compiler)) {
	constantInterceptor = backend.jsArrayClass;
	} else if (input.isNumber(compiler) &&
	!interceptedClasses.contains(backend.jsIntClass) &&
	!interceptedClasses.contains(backend.jsDoubleClass)) {
	// If the method being intercepted is not defined in [int] or [double] we
	// can safely use the number interceptor. This is because none of the
	// [int] or [double] methods are called from a method defined on [num].
	constantInterceptor = backend.jsNumberClass;
	} else {
	// Try to find constant interceptor for a native class. If the receiver
	// is constrained to a leaf native class, we can use the class's
	// interceptor directly.

	// TODO(sra): Key DOM classes like Node, Element and Event are not leaf
	// classes. When the receiver type is not a leaf class, we might still be
	// able to use the receiver class as a constant interceptor. It is
	// usually the case that methods defined on a non-leaf class don't test
	// for a subclass or call methods defined on a subclass. Provided the
	// code is completely insensitive to the specific instance subclasses, we
	// can use the non-leaf class directly.
	ClassElement element = input.instructionType.singleClass(compiler);
	if (element != null && element.isNative()) {
	constantInterceptor = element;
	}
	}

	if (constantInterceptor == null) return null;

	// If we just happen to be in an instance method of the constant
	// interceptor, `this` is a shorter alias.
	if (constantInterceptor == work.element.getEnclosingClass() &&
	graph.thisInstruction != null) {
	return graph.thisInstruction;
	}

	Constant constant = new InterceptorConstant(constantInterceptor.thisType);
	return graph.addConstant(constant, compiler);
	}

	HInstruction findDominator(Iterable<HInstruction> instructions) {
	HInstruction result;
	L1: for (HInstruction candidate in instructions) {
	for (HInstruction current in instructions) {
	if (current != candidate && !candidate.dominates(current)) continue L1;
	}
	result = candidate;
	break;
	}
	return result;
	}

	bool visitInterceptor(HInterceptor node) {
	if (node.isConstant()) return false;

	// If the interceptor is used by multiple instructions, specialize
	// it with a set of classes it intercepts.
	Set<ClassElement> interceptedClasses;
	JavaScriptBackend backend = compiler.backend;
	HInstruction dominator = findDominator(node.usedBy);
	// If there is a call that dominates all other uses, we can use just the
	// selector of that instruction.
	if (dominator is HInvokeDynamic &&
	dominator.isCallOnInterceptor(compiler) &&
	node == dominator.receiver) {
	interceptedClasses =
	backend.getInterceptedClassesOn(dominator.selector.name);

	// If we found that we need number, we must still go through all
	// uses to check if they require int, or double.
	if (interceptedClasses.contains(backend.jsNumberClass) &&
	!(interceptedClasses.contains(backend.jsDoubleClass) \|\|
	interceptedClasses.contains(backend.jsIntClass))) {
	for (HInstruction user in node.usedBy) {
	if (user is! HInvoke) continue;
	Set<ClassElement> intercepted =
	backend.getInterceptedClassesOn(user.selector.name);
	if (intercepted.contains(backend.jsIntClass)) {
	interceptedClasses.add(backend.jsIntClass);
	}
	if (intercepted.contains(backend.jsDoubleClass)) {
	interceptedClasses.add(backend.jsDoubleClass);
	}
	}
	}
	} else {
	interceptedClasses = new Set<ClassElement>();
	for (HInstruction user in node.usedBy) {
	if (user is HInvokeDynamic &&
	user.isCallOnInterceptor(compiler) &&
	node == user.receiver) {
	interceptedClasses.addAll(
	backend.getInterceptedClassesOn(user.selector.name));
	} else {
	// Use a most general interceptor for other instructions, example,
	// is-checks and escaping interceptors.
	interceptedClasses.addAll(backend.interceptedClasses);
	break;
	}
	}
	}

	HInstruction receiver = node.receiver;
	if (canUseSelfForInterceptor(receiver, interceptedClasses)) {
	return rewriteToUseSelfAsInterceptor(node, receiver);
	}

	// Try computing a constant interceptor.
	HInstruction constantInterceptor =
	tryComputeConstantInterceptor(receiver, interceptedClasses);
	if (constantInterceptor != null) {
	node.block.rewrite(node, constantInterceptor);
	return false;
	}

	node.interceptedClasses = interceptedClasses;

	// Try creating a one-shot interceptor.
	if (node.usedBy.length != 1) return false;
	if (node.usedBy[0] is !HInvokeDynamic) return false;

	HInvokeDynamic user = node.usedBy[0];

	// If [node] was loop hoisted, we keep the interceptor.
	if (!user.hasSameLoopHeaderAs(node)) return false;

	// Replace the user with a [HOneShotInterceptor].
	HConstant nullConstant = graph.addConstantNull(compiler);
	List<HInstruction> inputs = new List<HInstruction>.from(user.inputs);
	inputs[0] = nullConstant;
	HOneShotInterceptor interceptor = new HOneShotInterceptor(
	user.selector, inputs, user.instructionType, node.interceptedClasses);
	interceptor.sourcePosition = user.sourcePosition;
	interceptor.sourceElement = user.sourceElement;

	HBasicBlock block = user.block;
	block.addAfter(user, interceptor);
	block.rewrite(user, interceptor);
	block.remove(user);
	return true;
	}

	bool rewriteToUseSelfAsInterceptor(HInterceptor node, HInstruction receiver) {
	node.block.rewrite(node, receiver);
	return false;
	}

	bool visitOneShotInterceptor(HOneShotInterceptor node) {
	HInstruction constant = tryComputeConstantInterceptor(
	node.inputs[1], node.interceptedClasses);

	if (constant == null) return false;

	Selector selector = node.selector;
	HInstruction instruction;
	if (selector.isGetter()) {
	instruction = new HInvokeDynamicGetter(
	selector,
	node.element,
	<HInstruction>[constant, node.inputs[1]],
	node.instructionType);
	} else if (selector.isSetter()) {
	instruction = new HInvokeDynamicSetter(
	selector,
	node.element,
	<HInstruction>[constant, node.inputs[1], node.inputs[2]],
	node.instructionType);
	} else {
	List<HInstruction> inputs = new List<HInstruction>.from(node.inputs);
	inputs[0] = constant;
	instruction = new HInvokeDynamicMethod(
	selector, inputs, node.instructionType, true);
	}

	HBasicBlock block = node.block;
	block.addAfter(node, instruction);
	block.rewrite(node, instruction);
	return true;
	}
	}