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array creation is also safe if length comes from another array's length

This commit is contained in:
Martin Mohr 2016-10-27 13:36:11 +02:00 committed by Martin Hecker
parent 13a7b5459e
commit 4a7efc8c78
1 changed files with 10 additions and 2 deletions
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12
com.ibm.wala.core/src/com/ibm/wala/classLoader/ShrikeIRFactory.java
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@ -16,12 +16,13 @@ import com.ibm.wala.cfg.ControlFlowGraph;
import com.ibm.wala.cfg.ShrikeCFG;
import com.ibm.wala.ipa.callgraph.Context;
import com.ibm.wala.shrikeCT.InvalidClassFileException;
import com.ibm.wala.ssa.DefUse;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.IRFactory;
import com.ibm.wala.ssa.SSAArrayLengthInstruction;
import com.ibm.wala.ssa.SSABuilder;
import com.ibm.wala.ssa.SSACFG;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.ssa.SSAInstructionFactory;
import com.ibm.wala.ssa.SSANewInstruction;
import com.ibm.wala.ssa.SSAOptions;
import com.ibm.wala.ssa.ShrikeIndirectionData;
@ -74,13 +75,14 @@ public class ShrikeIRFactory implements IRFactory<IBytecodeMethod> {
DeadAssignmentElimination.perform(this);
}
private void pruneExceptionsForSafeArrayCreations() {
DefUse du = new DefUse(this);
for (int i = 0; i < newInstrs.length; i++) {
SSAInstruction instr = newInstrs[i];
if (instr instanceof SSANewInstruction) {
SSANewInstruction newInstr = (SSANewInstruction) instr;
if (newInstr.getConcreteType().isArrayType()) {
int vLength = newInstr.getUse(0);
if (symbolTable.isIntegerConstant(vLength) && symbolTable.getIntValue(vLength) >= 0) {
if (isNonNegativeConstant(vLength) || isDefdByArrayLength(vLength, du)) {
newInstrs[i] = new SSANewInstruction(newInstr.iindex, newInstr.getDef(), newInstr.getNewSite(), new int[] { vLength }) {
@Override
public Collection<TypeReference> getExceptionTypes() {
@ -92,6 +94,12 @@ public class ShrikeIRFactory implements IRFactory<IBytecodeMethod> {
}
}
}
private boolean isNonNegativeConstant(int vLength) {
return symbolTable.isIntegerConstant(vLength) && symbolTable.getIntValue(vLength) >= 0;
}
private boolean isDefdByArrayLength(int vLength, DefUse du) {
return du.getDef(vLength) instanceof SSAArrayLengthInstruction;
}
@Override
protected String instructionPosition(int instructionIndex) {
try {