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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
/*
* ProGuardCORE -- library to process Java bytecode.
*
* Copyright (c) 2002-2020 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.evaluation;
import java.util.Arrays;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import proguard.classfile.Clazz;
import proguard.classfile.Method;
import proguard.classfile.attribute.Attribute;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.attribute.ExceptionInfo;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.attribute.visitor.ExceptionInfoVisitor;
import proguard.classfile.editor.ClassEstimates;
import proguard.classfile.instruction.BranchInstruction;
import proguard.classfile.instruction.ConstantInstruction;
import proguard.classfile.instruction.Instruction;
import proguard.classfile.instruction.InstructionFactory;
import proguard.classfile.instruction.LookUpSwitchInstruction;
import proguard.classfile.instruction.SimpleInstruction;
import proguard.classfile.instruction.TableSwitchInstruction;
import proguard.classfile.instruction.VariableInstruction;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.BranchTargetFinder;
import proguard.classfile.visitor.ExceptionHandlerFilter;
import proguard.evaluation.exception.EmptyCodeAttributeException;
import proguard.evaluation.exception.ExcessiveComplexityException;
import proguard.evaluation.exception.StackGeneralizationException;
import proguard.evaluation.exception.VariablesGeneralizationException;
import proguard.evaluation.util.DebugPrinter;
import proguard.evaluation.util.PartialEvaluatorStateTracker;
import proguard.evaluation.value.BasicValueFactory;
import proguard.evaluation.value.InstructionOffsetValue;
import proguard.evaluation.value.Value;
import proguard.evaluation.value.ValueFactory;
import proguard.exception.ErrorId;
import proguard.exception.InstructionExceptionFormatter;
import proguard.exception.ProguardCoreException;
import proguard.util.CircularIntBuffer;
/**
* This {@link AttributeVisitor} performs partial evaluation on the code attributes that it visits.
*
* @author Eric Lafortune
*/
public class PartialEvaluator implements AttributeVisitor, ExceptionInfoVisitor {
private static final boolean DEBUG = false;
private static final boolean DEBUG_RESULTS = false;
/**
* Enables new exceptions to be thrown during evaluation. These are exceptions that are not thrown
* by the original ProGuard code. This is a temporary flag to allow the new exceptions to be
* tested. TODO: Remove this flag when the new exceptions are stable and will not break any
* dependent code.
*/
public static boolean ENABLE_NEW_EXCEPTIONS =
System.getProperty("proguard.pe.newexceptions") != null;
private static final Logger logger = LogManager.getLogger(PartialEvaluator.class);
// The analysis will generalize stack/vars after visiting an instruction this many times.
private static final int GENERALIZE_AFTER_N_EVALUATIONS = 5;
// If the analysis visits an instruction this many times (this can happen e.g. for big switches),
// the analysis of this method is forcibly stopped and a ExcessiveComplexityException is thrown.
// By default (value set to -1), the analysis is not forcibly stopped.
private int stopAnalysisAfterNEvaluations = -1;
public static final int NONE = -2;
public static final int AT_METHOD_ENTRY = -1;
public static final int AT_CATCH_ENTRY = -1;
private final ValueFactory valueFactory;
private final InvocationUnit invocationUnit;
private final boolean evaluateAllCode;
private final int prettyInstructionBuffered;
private final InstructionVisitor extraInstructionVisitor;
private InstructionOffsetValue[] branchOriginValues =
new InstructionOffsetValue[ClassEstimates.TYPICAL_CODE_LENGTH];
private InstructionOffsetValue[] branchTargetValues =
new InstructionOffsetValue[ClassEstimates.TYPICAL_CODE_LENGTH];
private TracedVariables[] variablesBefore =
new TracedVariables[ClassEstimates.TYPICAL_CODE_LENGTH];
private TracedStack[] stacksBefore = new TracedStack[ClassEstimates.TYPICAL_CODE_LENGTH];
private TracedVariables[] variablesAfter =
new TracedVariables[ClassEstimates.TYPICAL_CODE_LENGTH];
private TracedStack[] stacksAfter = new TracedStack[ClassEstimates.TYPICAL_CODE_LENGTH];
private boolean[] generalizedContexts = new boolean[ClassEstimates.TYPICAL_CODE_LENGTH];
private int[] evaluationCounts = new int[ClassEstimates.TYPICAL_CODE_LENGTH];
private boolean evaluateExceptions;
private int codeLength;
private PartialEvaluatorStateTracker stateTracker;
private final BasicBranchUnit branchUnit;
private final BranchTargetFinder branchTargetFinder;
private final java.util.Stack callingInstructionBlockStack;
private final java.util.Stack instructionBlockStack = new java.util.Stack<>();
/** Creates a simple PartialEvaluator. */
public PartialEvaluator() {
this(new BasicValueFactory());
}
/**
* Creates a new PartialEvaluator.
*
* @param valueFactory the value factory that will create all values during evaluation.
*/
public PartialEvaluator(ValueFactory valueFactory) {
this(valueFactory, new BasicInvocationUnit(valueFactory), true);
}
/**
* Creates a new PartialEvaluator.
*
* @param valueFactory the value factory that will create all values during the evaluation.
* @param invocationUnit the invocation unit that will handle all communication with other fields
* and methods.
* @param evaluateAllCode a flag that specifies whether all casts, branch targets, and exception
* handlers should be evaluated, even if they are unnecessary or unreachable.
*/
public PartialEvaluator(
ValueFactory valueFactory, InvocationUnit invocationUnit, boolean evaluateAllCode) {
this(valueFactory, invocationUnit, evaluateAllCode, null);
}
/**
* Creates a new PartialEvaluator.
*
* @param valueFactory the value factory that will create all values during the evaluation.
* @param invocationUnit the invocation unit that will handle all communication with other fields
* and methods.
* @param evaluateAllCode a flag that specifies whether all branch targets and exception handlers
* should be evaluated, even if they are unreachable.
* @param extraInstructionVisitor an optional extra visitor for all instructions right before they
* are executed.
*/
public PartialEvaluator(
ValueFactory valueFactory,
InvocationUnit invocationUnit,
boolean evaluateAllCode,
InstructionVisitor extraInstructionVisitor) {
this(
valueFactory,
invocationUnit,
evaluateAllCode,
extraInstructionVisitor,
evaluateAllCode ? new BasicBranchUnit() : new TracedBranchUnit(),
new BranchTargetFinder(),
null);
}
/**
* Creates a new PartialEvaluator.
*
* @param valueFactory the value factory that will create all values during evaluation.
* @param invocationUnit the invocation unit that will handle all communication with other fields
* and methods.
* @param evaluateAllCode a flag that specifies whether all casts, branch targets, and exception
* handlers should be evaluated, even if they are unnecessary or unreachable.
* @param branchUnit the branch unit that will handle all branches.
* @param branchTargetFinder the utility class that will find all branches.
* @param callingInstructionBlockStack the stack of instruction blocks to be evaluated
*/
private PartialEvaluator(
ValueFactory valueFactory,
InvocationUnit invocationUnit,
boolean evaluateAllCode,
InstructionVisitor extraInstructionVisitor,
BasicBranchUnit branchUnit,
BranchTargetFinder branchTargetFinder,
java.util.Stack callingInstructionBlockStack) {
this.valueFactory = valueFactory;
this.invocationUnit = invocationUnit;
this.evaluateAllCode = evaluateAllCode;
// To always support pretty printing, set this default value larger than 0.
this.prettyInstructionBuffered = 7;
this.extraInstructionVisitor = extraInstructionVisitor;
this.branchUnit = branchUnit;
this.branchTargetFinder = branchTargetFinder;
this.callingInstructionBlockStack =
callingInstructionBlockStack == null
? this.instructionBlockStack
: callingInstructionBlockStack;
if (DEBUG || DEBUG_RESULTS) {
this.stateTracker = new DebugPrinter(DEBUG, DEBUG_RESULTS);
}
}
/** Builds this PartialEvaluator using the (partly) filled Builder. */
private PartialEvaluator(Builder builder) {
this.valueFactory =
builder.valueFactory == null ? new BasicValueFactory() : builder.valueFactory;
this.invocationUnit =
builder.invocationUnit == null
? new BasicInvocationUnit(valueFactory)
: builder.invocationUnit;
this.evaluateAllCode = builder.evaluateAllCode;
this.prettyInstructionBuffered = builder.prettyInstructionBuffered;
this.extraInstructionVisitor = builder.extraInstructionVisitor;
this.branchUnit =
builder.branchUnit == null
? (evaluateAllCode ? new BasicBranchUnit() : new TracedBranchUnit())
: builder.branchUnit;
this.branchTargetFinder =
builder.branchTargetFinder == null ? new BranchTargetFinder() : builder.branchTargetFinder;
this.callingInstructionBlockStack =
builder.callingInstructionBlockStack == null
? this.instructionBlockStack
: builder.callingInstructionBlockStack;
this.stopAnalysisAfterNEvaluations = builder.stopAnalysisAfterNEvaluations;
if (builder.stateTracker == null && (DEBUG || DEBUG_RESULTS)) {
this.stateTracker = new DebugPrinter(DEBUG, DEBUG_RESULTS);
} else {
this.stateTracker = builder.stateTracker;
}
}
public static class Builder {
private ValueFactory valueFactory;
private InvocationUnit invocationUnit;
private boolean evaluateAllCode = true;
// To always support pretty printing, set this default value larger than 0.
private int prettyInstructionBuffered = 7;
private InstructionVisitor extraInstructionVisitor;
private BasicBranchUnit branchUnit;
private BranchTargetFinder branchTargetFinder;
private java.util.Stack callingInstructionBlockStack;
private int stopAnalysisAfterNEvaluations = -1; // disabled by default
private PartialEvaluatorStateTracker stateTracker;
public static Builder create() {
return new Builder();
}
private Builder() {}
public PartialEvaluator build() {
return new PartialEvaluator(this);
}
public Builder setStateTracker(PartialEvaluatorStateTracker stateTracker) {
this.stateTracker = stateTracker;
return this;
}
/** the value factory that will create all values during evaluation. */
public Builder setValueFactory(ValueFactory valueFactory) {
this.valueFactory = valueFactory;
return this;
}
/** The invocation unit that will handle all communication with other fields and methods. */
public Builder setInvocationUnit(InvocationUnit invocationUnit) {
this.invocationUnit = invocationUnit;
return this;
}
/**
* Specifies whether all casts, branch targets, and exceptionhandlers should be evaluated, even
* if they are unnecessary or unreachable.
*/
public Builder setEvaluateAllCode(boolean evaluateAllCode) {
this.evaluateAllCode = evaluateAllCode;
return this;
}
/**
* Specifies how many instructions should be considered in the context of a pretty message. When
* <= 0, no pretty printing is applied.
*/
public Builder setPrettyPrinting(int prettyInstructionBuffered) {
this.prettyInstructionBuffered = prettyInstructionBuffered;
return this;
}
/** Disable pretty printing of errors. */
public Builder disablePrettyPrinting() {
return this.setPrettyPrinting(0);
}
/** an optional extra visitor for all instructions right before they are executed. */
public Builder setExtraInstructionVisitor(InstructionVisitor extraInstructionVisitor) {
this.extraInstructionVisitor = extraInstructionVisitor;
return this;
}
/** The branch unit that will handle all branches. */
public Builder setBranchUnit(BasicBranchUnit branchUnit) {
this.branchUnit = branchUnit;
return this;
}
/** The utility class that will find all branches. */
public Builder setBranchTargetFinder(BranchTargetFinder branchTargetFinder) {
this.branchTargetFinder = branchTargetFinder;
return this;
}
/** the stack of instruction blocks to be evaluated. */
public Builder setCallingInstructionBlockStack(
java.util.Stack callingInstructionBlockStack) {
this.callingInstructionBlockStack = callingInstructionBlockStack;
return this;
}
/**
* The analysis of one method will forcibly stop (throwing a ExcessiveComplexityException) after
* this many evaluations of a single instruction.
*/
public Builder stopAnalysisAfterNEvaluations(int stopAnalysisAfterNEvaluations) {
this.stopAnalysisAfterNEvaluations = stopAnalysisAfterNEvaluations;
return this;
}
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
// DEBUG = DEBUG_RESULTS =
// clazz.getName().equals("abc/Def") &&
// method.getName(clazz).equals("abc");
// TODO: Remove this when the partial evaluator has stabilized.
// Catch any unexpected exceptions from the actual visiting method.
try {
// Process the code.
visitCodeAttribute0(clazz, method, codeAttribute);
} catch (ProguardCoreException ex) {
if (stateTracker != null) {
stateTracker.registerException(clazz, method, codeAttribute, this, ex);
}
throw ex;
} catch (RuntimeException ex) {
ProguardCoreException proguardCoreException =
new ProguardCoreException(
ErrorId.PARTIAL_EVALUATOR_ERROR2,
ex,
"Unexpected error while performing partial evaluation:{} Class = [{}]{} Method = [{}{}]{} Exception = [{}] ({})",
System.lineSeparator(),
clazz.getName(),
System.lineSeparator(),
method.getName(clazz),
method.getDescriptor(clazz),
System.lineSeparator(),
ex.getClass().getName(),
ex.getMessage());
if (stateTracker != null) {
stateTracker.registerException(clazz, method, codeAttribute, this, proguardCoreException);
}
throw proguardCoreException;
}
}
public void visitCodeAttribute0(Clazz clazz, Method method, CodeAttribute codeAttribute) {
// Evaluate the instructions, starting at the entry point.
// Empty code attribute, do not analyze
if (codeAttribute.code.length == 0) {
throw new EmptyCodeAttributeException("Empty code attribute found during partial evaluation");
}
// Reuse the existing variables and stack objects, ensuring the right size.
TracedVariables variables = new TracedVariables(codeAttribute.u2maxLocals);
TracedStack stack = new TracedStack(codeAttribute.u2maxStack);
// Initialize the reusable arrays and variables.
initializeArrays(codeAttribute);
initializeParameters(clazz, method, codeAttribute, variables);
if (stateTracker != null)
stateTracker.startCodeAttribute(clazz, method, codeAttribute, variables);
// Reset stacks.
instructionBlockStack.clear();
callingInstructionBlockStack.clear();
// Find all instruction offsets,...
codeAttribute.accept(clazz, method, branchTargetFinder);
// Start executing the first instruction block.
evaluateInstructionBlockAndExceptionHandlers(
clazz, method, codeAttribute, variables, stack, 0, codeAttribute.u4codeLength);
if (stateTracker != null) stateTracker.evaluationResults(clazz, method, codeAttribute, this);
}
/** Returns whether a block of instructions is ever used. */
public boolean isTraced(int startOffset, int endOffset) {
for (int index = startOffset; index < endOffset; index++) {
if (isTraced(index)) {
return true;
}
}
return false;
}
/**
* Returns whether the instruction at the given offset has ever been executed during the partial
* evaluation.
*/
public boolean isTraced(int instructionOffset) {
return evaluationCounts[instructionOffset] > 0;
}
/** Returns whether there is an instruction at the given offset. */
public boolean isInstruction(int instructionOffset) {
return branchTargetFinder.isInstruction(instructionOffset);
}
/** Returns whether the instruction at the given offset is the target of any kind. */
public boolean isTarget(int instructionOffset) {
return branchTargetFinder.isTarget(instructionOffset);
}
/** Returns whether the instruction at the given offset is the origin of a branch instruction. */
public boolean isBranchOrigin(int instructionOffset) {
return branchTargetFinder.isBranchOrigin(instructionOffset);
}
/** Returns whether the instruction at the given offset is the target of a branch instruction. */
public boolean isBranchTarget(int instructionOffset) {
return branchTargetFinder.isBranchTarget(instructionOffset);
}
/**
* Returns whether the instruction at the given offset is the target of a branch instruction or an
* exception.
*/
public boolean isBranchOrExceptionTarget(int instructionOffset) {
return branchTargetFinder.isBranchTarget(instructionOffset)
|| branchTargetFinder.isExceptionHandler(instructionOffset);
}
/** Returns whether the instruction at the given offset is the start of an exception handler. */
public boolean isExceptionHandler(int instructionOffset) {
return branchTargetFinder.isExceptionHandler(instructionOffset);
}
/** Returns whether the instruction at the given offset is the start of a subroutine. */
public boolean isSubroutineStart(int instructionOffset) {
return branchTargetFinder.isSubroutineStart(instructionOffset);
}
/** Returns whether the instruction at the given offset is a subroutine invocation. */
public boolean isSubroutineInvocation(int instructionOffset) {
return branchTargetFinder.isSubroutineInvocation(instructionOffset);
}
/** Returns whether the instruction at the given offset is part of a subroutine. */
public boolean isSubroutine(int instructionOffset) {
return branchTargetFinder.isSubroutine(instructionOffset);
}
/**
* Returns whether the subroutine at the given offset is ever returning by means of a regular
* 'ret' instruction.
*/
public boolean isSubroutineReturning(int instructionOffset) {
return branchTargetFinder.isSubroutineReturning(instructionOffset);
}
/** Returns the offset after the subroutine that starts at the given offset. */
public int subroutineEnd(int instructionOffset) {
return branchTargetFinder.subroutineEnd(instructionOffset);
}
// /**
// * Returns the instruction offset at which the object instance that is
// * created at the given 'new' instruction offset is initialized, or
// * NONE if it is not being created.
// */
// public int initializationOffset(int instructionOffset)
// {
// return branchTargetFinder.initializationOffset(instructionOffset);
// }
// /**
// * Returns whether the method is an instance initializer.
// */
// public boolean isInitializer()
// {
// return branchTargetFinder.isInitializer();
// }
// /**
// * Returns the instruction offset at which this initializer is calling
// * the "super" or "this" initializer method, or NONE if it is
// * not an initializer.
// */
// public int superInitializationOffset()
// {
// return branchTargetFinder.superInitializationOffset();
// }
/** Returns whether the instruction at the given offset creates a new, uninitialized instance. */
public boolean isCreation(int offset) {
return branchTargetFinder.isCreation(offset);
}
/**
* Returns whether the instruction at the given offset is the special invocation of an instance
* initializer.
*/
public boolean isInitializer(int offset) {
return branchTargetFinder.isInitializer(offset);
}
/** Returns the variables before execution of the instruction at the given offset. */
public TracedVariables getVariablesBefore(int instructionOffset) {
return variablesBefore[instructionOffset];
}
/** Returns the variables after execution of the instruction at the given offset. */
public TracedVariables getVariablesAfter(int instructionOffset) {
return variablesAfter[instructionOffset];
}
/** Returns the stack before execution of the instruction at the given offset. */
public TracedStack getStackBefore(int instructionOffset) {
return stacksBefore[instructionOffset];
}
/** Returns the stack after execution of the instruction at the given offset. */
public TracedStack getStackAfter(int instructionOffset) {
return stacksAfter[instructionOffset];
}
/** Returns the instruction offsets that branch to the given instruction offset. */
public InstructionOffsetValue branchOrigins(int instructionOffset) {
return branchOriginValues[instructionOffset];
}
/** Returns the instruction offsets to which the given instruction offset branches. */
public InstructionOffsetValue branchTargets(int instructionOffset) {
return branchTargetValues[instructionOffset];
}
/**
* Returns a filtering version of the given instruction visitor that only visits traced
* instructions.
*/
public InstructionVisitor tracedInstructionFilter(InstructionVisitor instructionVisitor) {
return tracedInstructionFilter(true, instructionVisitor);
}
/**
* Returns a filtering version of the given instruction visitor that only visits traced or
* untraced instructions.
*/
public InstructionVisitor tracedInstructionFilter(
boolean traced, InstructionVisitor instructionVisitor) {
return new MyTracedInstructionFilter(traced, instructionVisitor);
}
// Utility methods to evaluate instruction blocks.
/** Pushes block of instructions to be executed in the calling partial evaluator. */
private void pushCallingInstructionBlock(
TracedVariables variables, TracedStack stack, int startOffset) {
callingInstructionBlockStack.push(new InstructionBlock(variables, stack, startOffset));
}
/** Pushes block of instructions to be executed in this partial evaluator. */
private void pushInstructionBlock(TracedVariables variables, TracedStack stack, int startOffset) {
instructionBlockStack.push(new InstructionBlock(variables, stack, startOffset));
}
/**
* Evaluates the instruction block and the exception handlers covering the given instruction range
* in the given code.
*/
private void evaluateInstructionBlockAndExceptionHandlers(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
TracedVariables variables,
TracedStack stack,
int startOffset,
int endOffset) {
evaluateInstructionBlock(clazz, method, codeAttribute, variables, stack, startOffset);
evaluateExceptionHandlers(clazz, method, codeAttribute, startOffset, endOffset);
}
/**
* Evaluates a block of instructions, starting at the given offset and ending at a branch
* instruction, a return instruction, or a throw instruction.
*/
private void evaluateInstructionBlock(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
TracedVariables variables,
TracedStack stack,
int startOffset) {
// Execute the initial instruction block.
evaluateSingleInstructionBlock(clazz, method, codeAttribute, variables, stack, startOffset);
// Execute all resulting instruction blocks on the execution stack.
while (!instructionBlockStack.empty()) {
if (stateTracker != null) stateTracker.startBranchCodeBlockEvaluation(instructionBlockStack);
InstructionBlock instructionBlock = instructionBlockStack.pop();
evaluateSingleInstructionBlock(
clazz,
method,
codeAttribute,
instructionBlock.variables,
instructionBlock.stack,
instructionBlock.startOffset);
}
}
/**
* Evaluates a block of instructions, starting at the given offset and ending at a branch
* instruction, a return instruction, or a throw instruction. Instruction blocks that are to be
* evaluated as a result are pushed on the given stack.
*/
private void evaluateSingleInstructionBlock(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
TracedVariables variables,
TracedStack stack,
int startOffset) {
byte[] code = codeAttribute.code;
InstructionExceptionFormatter formatter =
prettyInstructionBuffered > 0
? new InstructionExceptionFormatter(
logger, new CircularIntBuffer(prettyInstructionBuffered), code, clazz, method)
: null;
if (stateTracker != null) {
stateTracker.startInstructionBlock(
clazz, method, codeAttribute, variables, stack, startOffset);
}
Processor processor =
new Processor(variables, stack, valueFactory, branchUnit, invocationUnit, evaluateAllCode);
int instructionOffset = startOffset;
int maxOffset = startOffset;
// Evaluate the subsequent instructions.
while (true) {
try {
if (formatter != null) {
formatter.registerInstructionOffset(instructionOffset);
}
if (maxOffset < instructionOffset) {
maxOffset = instructionOffset;
}
// Decode the instruction.
Instruction instruction = InstructionFactory.create(code, instructionOffset);
// Maintain a generalized local variable frame and stack at this
// instruction offset, before execution.
int evaluationCount = evaluationCounts[instructionOffset];
if (evaluationCount == 0) {
// First time we're passing by this instruction.
if (variablesBefore[instructionOffset] == null) {
// There's not even a context at this index yet.
variablesBefore[instructionOffset] = new TracedVariables(variables);
stacksBefore[instructionOffset] = new TracedStack(stack);
} else {
// Reuse the context objects at this index.
variablesBefore[instructionOffset].initialize(variables);
stacksBefore[instructionOffset].copy(stack);
}
// We'll execute in the generalized context, because it is
// the same as the current context.
generalizedContexts[instructionOffset] = true;
} else {
// Merge in the current context.
boolean variablesChanged;
boolean stackChanged;
try {
variablesChanged = variablesBefore[instructionOffset].generalize(variables, true);
;
} catch (IllegalArgumentException ex) {
throw new VariablesGeneralizationException(
ex, variablesBefore[instructionOffset], variables);
}
try {
stackChanged = stacksBefore[instructionOffset].generalize(stack);
} catch (IllegalArgumentException ex) {
throw new StackGeneralizationException(
clazz, method, ex, stacksBefore[instructionOffset], stack);
}
// System.out.println("GVars: "+variablesBefore[instructionOffset]);
// System.out.println("GStack: "+stacksBefore[instructionOffset]);
// Bail out if the current context is the same as last time.
if (!variablesChanged && !stackChanged && generalizedContexts[instructionOffset]) {
if (stateTracker != null)
stateTracker.skipInstructionBlock(
clazz,
method,
instructionOffset,
instruction,
variablesBefore[instructionOffset],
stacksBefore[instructionOffset],
evaluationCount);
break;
}
// See if this instruction has been evaluated an excessive number
// of times.
if (evaluationCount >= GENERALIZE_AFTER_N_EVALUATIONS) {
if (stateTracker != null)
stateTracker.generalizeInstructionBlock(
clazz, method, instructionOffset, instruction, variables, stack, evaluationCount);
if (stopAnalysisAfterNEvaluations != -1
&& evaluationCount >= stopAnalysisAfterNEvaluations) {
throw new ExcessiveComplexityException(
"Stopping evaluation after " + evaluationCount + " evaluations.");
}
// Continue, but generalize the current context.
// Note that the most recent variable values have to remain
// last in the generalizations, for the sake of the ret
// instruction.
variables.generalize(variablesBefore[instructionOffset], false);
stack.generalize(stacksBefore[instructionOffset]);
// We'll execute in the generalized context.
generalizedContexts[instructionOffset] = true;
} else {
// We'll execute in the current context.
generalizedContexts[instructionOffset] = false;
}
}
// We'll evaluate this instruction.
evaluationCounts[instructionOffset]++;
// Remember this instruction's offset with any stored value.
Value storeValue = new InstructionOffsetValue(instructionOffset);
variables.setProducerValue(storeValue);
stack.setProducerValue(storeValue);
// Reset the branch unit.
branchUnit.reset();
if (stateTracker != null)
stateTracker.startInstructionEvaluation(
clazz, method, instructionOffset, instruction, variables, stack, evaluationCount);
if (extraInstructionVisitor != null) {
// Visit the instruction with the optional visitor.
instruction.accept(
clazz, method, codeAttribute, instructionOffset, extraInstructionVisitor);
}
try {
// Process the instruction. The processor may modify the
// variables and the stack, and it may call the branch unit
// and the invocation unit.
instruction.accept(clazz, method, codeAttribute, instructionOffset, processor);
} catch (ProguardCoreException ex) {
throw ex;
} catch (RuntimeException ex) {
// Fallback to the default exception formatter.
if (formatter == null) {
logger.warn(
"Unexpected error while evaluating instruction:{} Class = [{}]{} Method = [{}{}]{} Instruction = {}{} Exception = [{}] ({})",
System.lineSeparator(),
clazz.getName(),
System.lineSeparator(),
method.getName(clazz),
method.getDescriptor(clazz),
System.lineSeparator(),
instruction.toString(clazz, instructionOffset),
System.lineSeparator(),
ex.getClass().getName(),
ex.getMessage(),
ex);
}
throw new ProguardCoreException(
ErrorId.PARTIAL_EVALUATOR_ERROR1,
ex,
"Unexpected error while evaluating instruction:{} Class = [{}]{} Method = [{}{}]{} Instruction = {}{} Exception = [{}] ({})",
System.lineSeparator(),
clazz.getName(),
System.lineSeparator(),
method.getName(clazz),
method.getDescriptor(clazz),
System.lineSeparator(),
instruction.toString(clazz, instructionOffset),
System.lineSeparator(),
ex.getClass().getName(),
ex.getMessage());
}
// Collect the branch targets from the branch unit.
InstructionOffsetValue branchTargets = branchUnit.getTraceBranchTargets();
int branchTargetCount = branchTargets.instructionOffsetCount();
if (stateTracker != null)
stateTracker.afterInstructionEvaluation(
clazz,
method,
instructionOffset,
instruction,
variables,
stack,
branchUnit,
branchTargets(instructionOffset));
// Maintain a generalized local variable frame and stack at this
// instruction offset, after execution.
if (evaluationCount == 0) {
// First time we're passing by this instruction.
if (variablesAfter[instructionOffset] == null) {
// There's not even a context at this index yet.
variablesAfter[instructionOffset] = new TracedVariables(variables);
stacksAfter[instructionOffset] = new TracedStack(stack);
} else {
// Reuse the context objects at this index.
variablesAfter[instructionOffset].initialize(variables);
stacksAfter[instructionOffset].copy(stack);
}
} else {
// Merge in the current context.
variablesAfter[instructionOffset].generalize(variables, true);
stacksAfter[instructionOffset].generalize(stack);
}
// Did the branch unit get called?
if (branchUnit.wasCalled()) {
// Accumulate the branch targets at this offset.
branchTargetValues[instructionOffset] =
branchTargetValues[instructionOffset] == null
? branchTargets
: branchTargetValues[instructionOffset].generalize(branchTargets);
// Are there no branch targets at all?
if (branchTargetCount == 0) {
// Exit from this code block.
break;
}
// Accumulate the branch origins at the branch target offsets.
InstructionOffsetValue instructionOffsetValue =
new InstructionOffsetValue(instructionOffset);
for (int index = 0; index < branchTargetCount; index++) {
int branchTarget = branchTargets.instructionOffset(index);
branchOriginValues[branchTarget] =
branchOriginValues[branchTarget] == null
? instructionOffsetValue
: branchOriginValues[branchTarget].generalize(instructionOffsetValue);
}
// Are there multiple branch targets?
if (branchTargetCount > 1) {
// Push them on the execution stack and exit from this block.
for (int index = 0; index < branchTargetCount; index++) {
if (stateTracker != null)
stateTracker.registerAlternativeBranch(
clazz,
method,
instructionOffset,
instruction,
variables,
stack,
index,
branchTargetCount,
branchTargets.instructionOffset(index));
pushInstructionBlock(
new TracedVariables(variables),
new TracedStack(stack),
branchTargets.instructionOffset(index));
}
break;
}
if (stateTracker != null)
stateTracker.definitiveBranch(
clazz, method, instructionOffset, instruction, variables, stack, branchTargets);
// Continue at the definite branch target.
instructionOffset = branchTargets.instructionOffset(0);
} else {
// Just continue with the next instruction.
instructionOffset += instruction.length(instructionOffset);
}
// Is this a subroutine invocation?
if (instruction.opcode == Instruction.OP_JSR
|| instruction.opcode == Instruction.OP_JSR_W) {
// Evaluate the subroutine in another partial evaluator.
evaluateSubroutine(clazz, method, codeAttribute, variables, stack, instructionOffset);
break;
} else if (instruction.opcode == Instruction.OP_RET) {
// Let the partial evaluator that has called the subroutine
// handle the evaluation after the return.
if (stateTracker != null)
stateTracker.registerSubroutineReturn(
clazz, method, instructionOffset, variables, stack);
pushCallingInstructionBlock(
new TracedVariables(variables), new TracedStack(stack), instructionOffset);
break;
}
} catch (ExcessiveComplexityException ex) {
// No need to log the exception with the formatter since this is an expected flow.
throw ex;
} catch (ProguardCoreException ex) {
if (formatter != null) {
formatter.printException(
ex, variablesBefore[instructionOffset], stacksBefore[instructionOffset]);
}
throw ex;
}
}
if (stateTracker != null)
stateTracker.instructionBlockDone(
clazz, method, codeAttribute, variables, stack, startOffset);
}
/**
* Evaluates a subroutine and its exception handlers, starting at the given offset and ending at a
* subroutine return instruction.
*/
private void evaluateSubroutine(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
TracedVariables variables,
TracedStack stack,
int subroutineStart) {
int subroutineEnd = branchTargetFinder.subroutineEnd(subroutineStart);
if (stateTracker != null)
stateTracker.startSubroutine(clazz, method, variables, stack, subroutineStart, subroutineEnd);
// Create a temporary partial evaluator, so there are no conflicts
// with variables that are alive across subroutine invocations, between
// different invocations.
PartialEvaluator subroutinePartialEvaluator = subRoutineEvaluator();
subroutinePartialEvaluator.initializeArrays(codeAttribute);
// Evaluate the subroutine.
subroutinePartialEvaluator.evaluateInstructionBlockAndExceptionHandlers(
clazz, method, codeAttribute, variables, stack, subroutineStart, subroutineEnd);
// Merge back the temporary partial evaluator. This way, we'll get
// the lowest common denominator of stacks and variables.
if (stateTracker != null)
stateTracker.generalizeSubroutine(
clazz, method, variables, stack, subroutineStart, subroutineEnd);
generalize(subroutinePartialEvaluator, 0, codeAttribute.u4codeLength);
if (stateTracker != null)
stateTracker.endSubroutine(clazz, method, variables, stack, subroutineStart, subroutineEnd);
}
/**
* Creates a new PartialEvaluator, based on this one. This partial evaluator is the subroutine
* calling partial evaluator.
*/
private PartialEvaluator subRoutineEvaluator() {
return Builder.create()
.setValueFactory(valueFactory)
.setInvocationUnit(invocationUnit)
.setEvaluateAllCode(evaluateAllCode)
.setExtraInstructionVisitor(extraInstructionVisitor)
.setBranchUnit(branchUnit)
.setBranchTargetFinder(branchTargetFinder)
.setCallingInstructionBlockStack(instructionBlockStack)
.setPrettyPrinting(prettyInstructionBuffered)
.setStateTracker(stateTracker)
.build();
}
/**
* Generalizes the results of this partial evaluator with those of another given partial
* evaluator, over a given range of instructions.
*/
private void generalize(PartialEvaluator other, int codeStart, int codeEnd) {
for (int offset = codeStart; offset < codeEnd; offset++) {
if (other.branchOriginValues[offset] != null) {
branchOriginValues[offset] =
branchOriginValues[offset] == null
? other.branchOriginValues[offset]
: branchOriginValues[offset].generalize(other.branchOriginValues[offset]);
}
if (other.isTraced(offset)) {
if (other.branchTargetValues[offset] != null) {
branchTargetValues[offset] =
branchTargetValues[offset] == null
? other.branchTargetValues[offset]
: branchTargetValues[offset].generalize(other.branchTargetValues[offset]);
}
if (evaluationCounts[offset] == 0) {
variablesBefore[offset] = other.variablesBefore[offset];
stacksBefore[offset] = other.stacksBefore[offset];
variablesAfter[offset] = other.variablesAfter[offset];
stacksAfter[offset] = other.stacksAfter[offset];
generalizedContexts[offset] = other.generalizedContexts[offset];
evaluationCounts[offset] = other.evaluationCounts[offset];
} else {
variablesBefore[offset].generalize(other.variablesBefore[offset], false);
stacksBefore[offset].generalize(other.stacksBefore[offset]);
variablesAfter[offset].generalize(other.variablesAfter[offset], false);
stacksAfter[offset].generalize(other.stacksAfter[offset]);
// generalizedContexts[offset]
evaluationCounts[offset] += other.evaluationCounts[offset];
}
}
}
}
/**
* Evaluates the exception handlers covering and targeting the given instruction range in the
* given code.
*/
private void evaluateExceptionHandlers(
Clazz clazz, Method method, CodeAttribute codeAttribute, int startOffset, int endOffset) {
if (stateTracker != null)
stateTracker.startExceptionHandlingForBlock(clazz, method, startOffset, endOffset);
ExceptionHandlerFilter exceptionEvaluator =
new ExceptionHandlerFilter(startOffset, endOffset, this);
// Evaluate the exception catch blocks, until their entry variables
// have stabilized.
do {
// Reset the flag to stop evaluating.
evaluateExceptions = false;
// Evaluate all relevant exception catch blocks once.
codeAttribute.exceptionsAccept(clazz, method, startOffset, endOffset, exceptionEvaluator);
} while (evaluateExceptions);
}
// Implementations for ExceptionInfoVisitor.
public void visitExceptionInfo(
Clazz clazz, Method method, CodeAttribute codeAttribute, ExceptionInfo exceptionInfo) {
int startPC = exceptionInfo.u2startPC;
int endPC = exceptionInfo.u2endPC;
// Do we have to evaluate this exception catch block?
if (mayThrowExceptions(clazz, method, codeAttribute, startPC, endPC)) {
int handlerPC = exceptionInfo.u2handlerPC;
int catchType = exceptionInfo.u2catchType;
if (stateTracker != null)
stateTracker.registerExceptionHandler(clazz, method, startPC, endPC, exceptionInfo);
// Reuse the existing variables and stack objects, ensuring the
// right size.
TracedVariables variables = new TracedVariables(codeAttribute.u2maxLocals);
TracedStack stack = new TracedStack(codeAttribute.u2maxStack);
// Initialize the trace values.
Value storeValue =
new InstructionOffsetValue(handlerPC | InstructionOffsetValue.EXCEPTION_HANDLER);
variables.setProducerValue(storeValue);
stack.setProducerValue(storeValue);
// Initialize the variables by generalizing the variables of the
// try block. Make sure to include the results of the last
// instruction for preverification.
generalizeVariables(startPC, endPC, evaluateAllCode, variables);
// Initialize the stack.
invocationUnit.enterExceptionHandler(
clazz, method, codeAttribute, handlerPC, catchType, stack);
int evaluationCount = evaluationCounts[handlerPC];
// Evaluate the instructions, starting at the entry point.
evaluateInstructionBlock(clazz, method, codeAttribute, variables, stack, handlerPC);
// Remember to evaluate all exception handlers once more.
if (!evaluateExceptions) {
evaluateExceptions = evaluationCount < evaluationCounts[handlerPC];
}
}
// else if (evaluateAllCode)
// {
// if (DEBUG) System.out.println("No information for partial evaluation of exception
// ["+startPC +" -> "+endPC +": "+exceptionInfo.u2handlerPC+"] yet");
//
// // We don't have any information on the try block yet, but we do
// // have to evaluate the exception handler.
// // Remember to evaluate all exception handlers once more.
// evaluateExceptions = true;
// }
else {
if (stateTracker != null)
stateTracker.registerUnusedExceptionHandler(clazz, method, startPC, endPC, exceptionInfo);
}
}
// Small utility methods.
/** Initializes the data structures for the variables, stack, etc. */
private void initializeArrays(CodeAttribute codeAttribute) {
int newCodeLength = codeAttribute.u4codeLength;
// Create new arrays for storing information at each instruction offset.
if (branchOriginValues.length < newCodeLength) {
// Create new arrays.
branchOriginValues = new InstructionOffsetValue[newCodeLength];
branchTargetValues = new InstructionOffsetValue[newCodeLength];
variablesBefore = new TracedVariables[newCodeLength];
stacksBefore = new TracedStack[newCodeLength];
variablesAfter = new TracedVariables[newCodeLength];
stacksAfter = new TracedStack[newCodeLength];
generalizedContexts = new boolean[newCodeLength];
evaluationCounts = new int[newCodeLength];
} else {
// Reset the old arrays.
Arrays.fill(branchOriginValues, 0, codeLength, null);
Arrays.fill(branchTargetValues, 0, codeLength, null);
Arrays.fill(generalizedContexts, 0, codeLength, false);
Arrays.fill(evaluationCounts, 0, codeLength, 0);
for (int index = 0; index < newCodeLength; index++) {
if (variablesBefore[index] != null) {
variablesBefore[index].reset(codeAttribute.u2maxLocals);
}
if (stacksBefore[index] != null) {
stacksBefore[index].reset(codeAttribute.u2maxStack);
}
if (variablesAfter[index] != null) {
variablesAfter[index].reset(codeAttribute.u2maxLocals);
}
if (stacksAfter[index] != null) {
stacksAfter[index].reset(codeAttribute.u2maxStack);
}
}
for (int index = newCodeLength; index < codeLength; index++) {
if (variablesBefore[index] != null) {
variablesBefore[index].reset(0);
}
if (stacksBefore[index] != null) {
stacksBefore[index].reset(0);
}
if (variablesAfter[index] != null) {
variablesAfter[index].reset(0);
}
if (stacksAfter[index] != null) {
stacksAfter[index].reset(0);
}
}
}
codeLength = newCodeLength;
}
/** Initializes the data structures for the variables, stack, etc. */
private void initializeParameters(
Clazz clazz, Method method, CodeAttribute codeAttribute, TracedVariables variables) {
// // Create the method parameters.
// TracedVariables parameters = new TracedVariables(codeAttribute.u2maxLocals);
//
// // Remember this instruction's offset with any stored value.
// Value storeValue = new InstructionOffsetValue(AT_METHOD_ENTRY);
// parameters.setProducerValue(storeValue);
// Create the method parameters.
Variables parameters = new Variables(codeAttribute.u2maxLocals);
// Initialize the method parameters.
invocationUnit.enterMethod(clazz, method, parameters);
// Initialize the variables with the parameters.
variables.initialize(parameters);
// Set the store value of each parameter variable. We store the
// variable indices of the parameters. These parameter offsets take
// into account Category 2 types.
for (int index = 0; index < parameters.size(); index++) {
InstructionOffsetValue producerValue =
new InstructionOffsetValue(index | InstructionOffsetValue.METHOD_PARAMETER);
variables.setProducerValue(index, producerValue);
}
}
/** Returns whether a block of instructions may ever throw an exception. */
private boolean mayThrowExceptions(
Clazz clazz, Method method, CodeAttribute codeAttribute, int startOffset, int endOffset) {
for (int index = startOffset; index < endOffset; index++) {
if (isTraced(index)
&& (evaluateAllCode
|| InstructionFactory.create(codeAttribute.code, index)
.mayInstanceThrowExceptions(clazz))) {
return true;
}
}
return false;
}
/** Generalize the local variable frames of a block of instructions. */
private void generalizeVariables(
int startOffset,
int endOffset,
boolean includeAfterLastInstruction,
TracedVariables generalizedVariables) {
boolean first = true;
int lastIndex = -1;
// Generalize the variables before each of the instructions in the block.
for (int index = startOffset; index < endOffset; index++) {
if (isTraced(index)) {
TracedVariables tracedVariables = variablesBefore[index];
if (first) {
// Initialize the variables with the first traced local
// variable frame.
generalizedVariables.initialize(tracedVariables);
first = false;
} else {
// Generalize the variables with the traced local variable
// frame. We can't use the return value, because local
// generalization can be different a couple of times,
// with the global generalization being the same.
generalizedVariables.generalize(tracedVariables, false);
}
lastIndex = index;
}
}
// Generalize the variables after the last instruction in the block,
// if required.
if (includeAfterLastInstruction && lastIndex >= 0) {
TracedVariables tracedVariables = variablesAfter[lastIndex];
if (first) {
// Initialize the variables with the local variable frame.
generalizedVariables.initialize(tracedVariables);
} else {
// Generalize the variables with the local variable frame.
generalizedVariables.generalize(tracedVariables, false);
}
}
// Just clear the variables if there aren't any traced instructions
// in the block.
if (first) {
generalizedVariables.reset(generalizedVariables.size());
}
}
/**
* It the analysis visits an instruction this many times (this can happen e.g. for big switches),
* the analysis of this method is forcibly stopped and a ExcessiveComplexityException is thrown.
*/
public PartialEvaluator stopAnalysisAfterNEvaluations(int stopAnalysisAfterNEvaluations) {
this.stopAnalysisAfterNEvaluations = stopAnalysisAfterNEvaluations;
return this;
}
/**
* This class represents an instruction block that has to be executed, starting with a given state
* at a given instruction offset.
*/
public static class InstructionBlock {
private final TracedVariables variables;
private final TracedStack stack;
private final int startOffset;
private InstructionBlock(TracedVariables variables, TracedStack stack, int startOffset) {
this.variables = variables;
this.stack = stack;
this.startOffset = startOffset;
}
}
/**
* This InstructionVisitor delegates its visits to a given InstructionVisitor, but only if the
* instruction has been traced (or not).
*/
private class MyTracedInstructionFilter implements InstructionVisitor {
private final boolean traced;
private final InstructionVisitor instructionVisitor;
public MyTracedInstructionFilter(boolean traced, InstructionVisitor instructionVisitor) {
this.traced = traced;
this.instructionVisitor = instructionVisitor;
}
// Implementations for InstructionVisitor.
public void visitSimpleInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
SimpleInstruction simpleInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitSimpleInstruction(
clazz, method, codeAttribute, offset, simpleInstruction);
}
}
public void visitVariableInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
VariableInstruction variableInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitVariableInstruction(
clazz, method, codeAttribute, offset, variableInstruction);
}
}
public void visitConstantInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
ConstantInstruction constantInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitConstantInstruction(
clazz, method, codeAttribute, offset, constantInstruction);
}
}
public void visitBranchInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
BranchInstruction branchInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitBranchInstruction(
clazz, method, codeAttribute, offset, branchInstruction);
}
}
public void visitTableSwitchInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
TableSwitchInstruction tableSwitchInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitTableSwitchInstruction(
clazz, method, codeAttribute, offset, tableSwitchInstruction);
}
}
public void visitLookUpSwitchInstruction(
Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int offset,
LookUpSwitchInstruction lookUpSwitchInstruction) {
if (shouldVisit(offset)) {
instructionVisitor.visitLookUpSwitchInstruction(
clazz, method, codeAttribute, offset, lookUpSwitchInstruction);
}
}
private boolean shouldVisit(int offset) {
return isTraced(offset) == traced;
}
}
}
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