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/*
* ProGuardCORE -- library to process Java bytecode.
*
* Copyright (c) 2002-2023 Guardsquare NV
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package proguard.analysis.datastructure.callgraph;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import proguard.analysis.CallResolver;
import proguard.analysis.CallVisitor;
import proguard.analysis.datastructure.CodeLocation;
import proguard.classfile.Method;
import proguard.classfile.MethodSignature;
import proguard.classfile.instruction.Instruction;
import proguard.classfile.instruction.InstructionUtil;
import proguard.classfile.util.ClassUtil;
import proguard.classfile.visitor.MemberVisitor;
import proguard.evaluation.value.IdentifiedReferenceValue;
import proguard.evaluation.value.Value;
/**
* Represents a method call. If the call target is a {@link Method} that is present in the class
* pool, a {@link ConcreteCall} is instantiated. If the call target is not a known method, a {@link
* SymbolicCall} is the appropriate subclass.
*
* @author Samuel Hopstock
*/
public abstract class Call {
private static final Logger log = LogManager.getLogger(Call.class);
/** The location where the call was invoked. */
public final CodeLocation caller;
/**
* Describes whether this call will throw a {@link NullPointerException} at runtime. Either {@link
* Value#NEVER}, {@link Value#MAYBE} or {@link Value#ALWAYS}.
*/
public final int throwsNullptr;
/**
* The instruction performing this call. There are several different ways of invoking a method
* call in the JVM:
*
*
* - {@link Instruction#OP_INVOKESTATIC}
*
- {@link Instruction#OP_INVOKEVIRTUAL}
*
- {@link Instruction#OP_INVOKEINTERFACE}
*
- {@link Instruction#OP_INVOKESPECIAL}
*
- {@link Instruction#OP_INVOKEDYNAMIC}
*
*
* See the {@link CallResolver} for more details.
*/
public final Instruction instruction;
/**
* If false, control flow in the calling method will always reach this call. Otherwise, whether
* the call will be invoked at runtime might depend on e.g. specific branches being taken.
*/
public final boolean controlFlowDependent;
/**
* If true, this call might only be one of several alternative targets, depending on the actual
* type of the called object during runtime. Otherwise, this call is the only possible target.
*/
public final boolean runtimeTypeDependent;
private Value instance;
private List arguments;
private Value returnValue;
private boolean valuesCleared;
protected Call(
CodeLocation caller,
Value instance,
List arguments,
Value returnValue,
int throwsNullptr,
Instruction instruction,
boolean controlFlowDependent,
boolean runtimeTypeDependent) {
this.caller = caller;
this.instance = instance;
this.arguments = arguments;
this.returnValue = returnValue;
this.throwsNullptr = throwsNullptr;
this.instruction = instruction;
this.controlFlowDependent = controlFlowDependent;
this.runtimeTypeDependent = runtimeTypeDependent;
}
/** Check if this call is static (no implicit {@link #instance} set) or not. */
public boolean isStatic() {
return InstructionUtil.isStaticCall(instruction.opcode);
}
/** The {@link MethodSignature} of the method that is being called. */
public abstract MethodSignature getTarget();
/** Check if this call's target is fully known or only parts of it (e.g. only the descriptor). */
public abstract boolean hasIncompleteTarget();
/** Returns the number of arguments. */
public int getArgumentCount() {
if (!valuesCleared) {
return arguments.size();
}
return ClassUtil.internalMethodParameterCount(getTarget().descriptor.toString());
}
/** Returns the number of elements that need to be popped from the JVM stack for this call. */
public int getJvmArgumentSize() {
return ClassUtil.internalMethodParameterSize(getTarget().descriptor.toString(), isStatic());
}
/**
* Get the value for a specific argument index.
*
* Note: This is only to be used in implementations of {@link
* CallVisitor#visitCall(Call)}. Afterwards, the values will have been cleared to reduce
* unnecessary memory usage, as argument values are not needed for the full call graph
* reconstruction.
*/
public Value getArgument(int index) {
if (valuesCleared) {
log.error("Argument requested after values have been cleared!");
return null;
}
if (arguments.size() <= index) {
return null;
}
return arguments.get(index);
}
public void setArguments(List arguments) {
this.arguments = arguments;
}
/**
* If this is a virtual call, this describes the this pointer of the object whose
* method is called, usually an {@link IdentifiedReferenceValue}. For static calls this is null.
*
* Note: This is only to be used in implementations of {@link
* CallVisitor#visitCall(Call)}. Afterwards, the value will have been cleared to reduce
* unnecessary memory usage, as the instance value is not needed for the full call graph
* reconstruction.
*/
public Value getInstance() {
if (valuesCleared) {
log.error("Instance requested after values have been cleared!");
return null;
}
return instance;
}
public void setInstance(Value instance) {
this.instance = instance;
}
/**
* Get the return value of this call.
*
*
Note: This is only to be used in implementations of {@link
* CallVisitor#visitCall(Call)}. Afterwards, the value will have been cleared to reduce
* unnecessary memory usage, as the return value is not needed for the full call graph
* reconstruction.
*/
public Value getReturnValue() {
if (valuesCleared) {
log.error("Return value requested after values have been cleared!");
return null;
}
return returnValue;
}
public void setReturnValue(Value returnValue) {
this.returnValue = returnValue;
}
/** Clear all {@link Value} object references from this call. */
public void clearValues() {
arguments = Collections.nCopies(arguments.size(), null);
returnValue = null;
instance = null;
valuesCleared = true;
}
/**
* Returns true if this call is always executed, no matter which branch in the methods are taken
* and which type the called object has during runtime.
*/
public boolean isCertainlyCalled() {
return !controlFlowDependent && !runtimeTypeDependent;
}
@Override
public String toString() {
String nullSuffix = "";
if (throwsNullptr == Value.ALWAYS) {
nullSuffix = " (always throws NullPointerException)";
} else if (throwsNullptr == Value.MAYBE) {
nullSuffix = " (might throw NullPointerException)";
}
return "[" + instruction.getName() + "] " + caller + " -> " + getTarget() + nullSuffix;
}
/**
* Prints a shorter version of the regular `toString()` without the caller or null pointer
* information.
*/
public String toSimpleString() {
return "[" + instruction.getName() + "] " + getTarget();
}
public void targetMethodAccept(MemberVisitor memberVisitor) {}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Call that = (Call) o;
return throwsNullptr == that.throwsNullptr
&& Objects.equals(caller, that.caller)
&& Objects.equals(arguments, that.arguments)
&& Objects.equals(instruction, that.instruction);
}
@Override
public int hashCode() {
return Objects.hash(caller, throwsNullptr);
}
}