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RopperMachine.javaAPI DocAndroid 1.5 API32581Wed May 06 22:41:02 BST 2009com.android.dx.cf.code

RopperMachine

public final class RopperMachine extends ValueAwareMachine
Machine implementation for use by {@link Ropper}.

Fields Summary
private static final com.android.dx.rop.cst.CstType
ARRAY_REFLECT_TYPE
non-null; array reflection class
private static final com.android.dx.rop.cst.CstMethodRef
MULTIANEWARRAY_METHOD
non-null; method constant for use in converting multianewarray instructions
private final Ropper
ropper
non-null; {@link Ropper} controlling this instance
private final ConcreteMethod
method
non-null; method being converted
private final com.android.dx.rop.code.TranslationAdvice
advice
non-null; translation advice
private final int
maxLocals
max locals of the method
private final ArrayList
insns
non-null; instructions for the rop basic block in-progress
private com.android.dx.rop.type.TypeList
catches
non-null; catches for the block currently being processed
private boolean
catchesUsed
whether the catches have been used in an instruction
private boolean
returns
whether the block contains a return
private int
primarySuccessorIndex
primary successor index
private int
extraBlockCount
>= 0; number of extra basic blocks required
private boolean
hasJsr
true if last processed block ends with a jsr or jsr_W
private boolean
blockCanThrow
true if an exception can be thrown by the last block processed
private ReturnAddress
returnAddress
If non-null, the ReturnAddress that was used by the terminating ret instruction. If null, there was no ret instruction encountered.
private com.android.dx.rop.code.Rop
returnOp
null-ok; the appropriate return op or null if it is not yet known
private com.android.dx.rop.code.SourcePosition
returnPosition
null-ok; the source position for the return block or null if it is not yet known
Constructors Summary
public RopperMachine(Ropper ropper, ConcreteMethod method, com.android.dx.rop.code.TranslationAdvice advice)
Constructs an instance.

param
ropper non-null; ropper controlling this instance
param
method non-null; method being converted
param
advice non-null; translation advice to use


                                 
        
              
        super(method.getEffectiveDescriptor());
        
        if (ropper == null) {
            throw new NullPointerException("ropper == null");
        }

        if (advice == null) {
            throw new NullPointerException("advice == null");
        }

        this.ropper = ropper;
        this.method = method;
        this.advice = advice;
        this.maxLocals = method.getMaxLocals();
        this.insns = new ArrayList<Insn>(25);
        this.catches = null;
        this.catchesUsed = false;
        this.returns = false;
        this.primarySuccessorIndex = -1;
        this.extraBlockCount = 0;
        this.blockCanThrow = false;
        this.returnOp = null;
        this.returnPosition = null;
Methods Summary
public booleancanThrow()

return
true if at least one of the insn processed since the last call to startBlock() can throw.

        return blockCanThrow;
public intgetExtraBlockCount()
Gets how many extra blocks will be needed to represent the block currently being translated. Each extra block should consist of one instruction from the end of the original block.

return
>= 0; the number of extra blocks needed

        return extraBlockCount;
public java.util.ArrayListgetInsns()
Gets the instructions array. It is shared and gets modified by subsequent calls to this instance.

return
non-null; the instructions array

        return insns;
public intgetPrimarySuccessorIndex()
Gets the primary successor index. This is the index into the successors list where the primary may be found or -1 if there are successors but no primary successor. This may return something other than -1 in the case of an instruction with no successors at all (primary or otherwise).

return
>= -1; the primary successor index

        return primarySuccessorIndex;
public ReturnAddressgetReturnAddress()

return
null-ok; return address of a ret instruction if encountered since last call to startBlock(). null if no ret instruction encountered.

        return returnAddress;
public com.android.dx.rop.code.RopgetReturnOp()
Gets the return opcode encountered, if any.

return
null-ok; the return opcode

        return returnOp;
public com.android.dx.rop.code.SourcePositiongetReturnPosition()
Gets the return position, if known.

return
null-ok; the return position

        return returnPosition;
private com.android.dx.rop.code.RegisterSpecListgetSources(int opcode, int stackPointer)
Helper for {@link #run}, which gets the list of sources for the. instruction.

param
opcode the opcode being translated
param
stackPointer >= 0; the stack pointer after the instruction's arguments have been popped
return
non-null; the sources

        int count = argCount();

        if (count == 0) {
            // We get an easy out if there aren't any sources.
            return RegisterSpecList.EMPTY;
        } 

        int localIndex = getLocalIndex();
        RegisterSpecList sources;

        if (localIndex >= 0) {
            // The instruction is operating on a local variable.
            sources = new RegisterSpecList(1);
            sources.set(0, RegisterSpec.make(localIndex, arg(0)));
        } else {
            sources = new RegisterSpecList(count);
            int regAt = stackPointer;
            for (int i = 0; i < count; i++) {
                RegisterSpec spec = RegisterSpec.make(regAt, arg(i));
                sources.set(i, spec);
                regAt += spec.getCategory();
            }

            switch (opcode) {
                case ByteOps.IASTORE: {
                    /*
                     * The Java argument order for array stores is
                     * (array, index, value), but the rop argument
                     * order is (value, array, index). The following
                     * code gets the right arguments in the right
                     * places.
                     */
                    if (count != 3) {
                        throw new RuntimeException("shouldn't happen");
                    }
                    RegisterSpec array = sources.get(0);
                    RegisterSpec index = sources.get(1);
                    RegisterSpec value = sources.get(2);
                    sources.set(0, value);
                    sources.set(1, array);
                    sources.set(2, index);
                    break;
                }
                case ByteOps.PUTFIELD: {
                    /*
                     * Similar to above: The Java argument order for
                     * putfield is (object, value), but the rop
                     * argument order is (value, object).
                     */
                    if (count != 2) {
                        throw new RuntimeException("shouldn't happen");
                    }
                    RegisterSpec obj = sources.get(0);
                    RegisterSpec value = sources.get(1);
                    sources.set(0, value);
                    sources.set(1, obj);
                    break;
                }
            }
        }

        sources.setImmutable();
        return sources;
public booleanhasJsr()

return
true if a JSR has ben encountered since the last call to startBlock()

        return hasJsr;
public booleanhasRet()

return
true if a RET has ben encountered since the last call to startBlock()

        return returnAddress != null;
private intjopToRopOpcode(int jop, com.android.dx.rop.cst.Constant cst)
Gets the register opcode for the given Java opcode.

param
jop >= 0; the Java opcode
param
cst null-ok; the constant argument, if any
return
>= 0; the corresponding register opcode

        switch (jop) {
            case ByteOps.POP:
            case ByteOps.POP2:
            case ByteOps.DUP:
            case ByteOps.DUP_X1:
            case ByteOps.DUP_X2:
            case ByteOps.DUP2:
            case ByteOps.DUP2_X1:
            case ByteOps.DUP2_X2:
            case ByteOps.SWAP:
            case ByteOps.JSR:
            case ByteOps.RET:
            case ByteOps.MULTIANEWARRAY: {
                // These need to be taken care of specially.
                break;
            }
            case ByteOps.NOP: {
                return RegOps.NOP;
            }
            case ByteOps.LDC:
            case ByteOps.LDC2_W: {
                return RegOps.CONST;
            }
            case ByteOps.ILOAD: 
            case ByteOps.ISTORE: {
                return RegOps.MOVE;
            }
            case ByteOps.IALOAD: {
                return RegOps.AGET;
            }
            case ByteOps.IASTORE: {
                return RegOps.APUT;
            }
            case ByteOps.IADD:
            case ByteOps.IINC: {
                return RegOps.ADD;
            }
            case ByteOps.ISUB: {
                return RegOps.SUB;
            }
            case ByteOps.IMUL: {
                return RegOps.MUL;
            }
            case ByteOps.IDIV: {
                return RegOps.DIV;
            }
            case ByteOps.IREM: {
                return RegOps.REM;
            }
            case ByteOps.INEG: {
                return RegOps.NEG;
            }
            case ByteOps.ISHL: {
                return RegOps.SHL;
            }
            case ByteOps.ISHR: {
                return RegOps.SHR;
            }
            case ByteOps.IUSHR: {
                return RegOps.USHR;
            }
            case ByteOps.IAND: {
                return RegOps.AND;
            }
            case ByteOps.IOR: {
                return RegOps.OR;
            }
            case ByteOps.IXOR: {
                return RegOps.XOR;
            }
            case ByteOps.I2L:
            case ByteOps.I2F:
            case ByteOps.I2D:
            case ByteOps.L2I:
            case ByteOps.L2F:
            case ByteOps.L2D:
            case ByteOps.F2I:
            case ByteOps.F2L:
            case ByteOps.F2D:
            case ByteOps.D2I:
            case ByteOps.D2L:
            case ByteOps.D2F: {
                return RegOps.CONV;
            }
            case ByteOps.I2B: {
                return RegOps.TO_BYTE;
            }
            case ByteOps.I2C: {
                return RegOps.TO_CHAR;
            }
            case ByteOps.I2S: {
                return RegOps.TO_SHORT;
            }
            case ByteOps.LCMP:
            case ByteOps.FCMPL:
            case ByteOps.DCMPL: {
                return RegOps.CMPL;
            }
            case ByteOps.FCMPG:
            case ByteOps.DCMPG: {
                return RegOps.CMPG;
            }
            case ByteOps.IFEQ:
            case ByteOps.IF_ICMPEQ:
            case ByteOps.IF_ACMPEQ:
            case ByteOps.IFNULL: {
                return RegOps.IF_EQ;
            }
            case ByteOps.IFNE:
            case ByteOps.IF_ICMPNE:
            case ByteOps.IF_ACMPNE:
            case ByteOps.IFNONNULL: {
                return RegOps.IF_NE;
            }
            case ByteOps.IFLT:
            case ByteOps.IF_ICMPLT: {
                return RegOps.IF_LT;
            }
            case ByteOps.IFGE:
            case ByteOps.IF_ICMPGE: {
                return RegOps.IF_GE;
            }
            case ByteOps.IFGT:
            case ByteOps.IF_ICMPGT: {
                return RegOps.IF_GT;
            }
            case ByteOps.IFLE:
            case ByteOps.IF_ICMPLE: {
                return RegOps.IF_LE;
            }
            case ByteOps.GOTO: {
                return RegOps.GOTO;
            }
            case ByteOps.LOOKUPSWITCH: {
                return RegOps.SWITCH;
            }
            case ByteOps.IRETURN:
            case ByteOps.RETURN: {
                return RegOps.RETURN;
            }
            case ByteOps.GETSTATIC: {
                return RegOps.GET_STATIC;
            }
            case ByteOps.PUTSTATIC: {
                return RegOps.PUT_STATIC;
            }
            case ByteOps.GETFIELD: {
                return RegOps.GET_FIELD;
            }
            case ByteOps.PUTFIELD: {
                return RegOps.PUT_FIELD;
            }
            case ByteOps.INVOKEVIRTUAL: {
                return RegOps.INVOKE_VIRTUAL;
            }
            case ByteOps.INVOKESPECIAL: {
                /*
                 * Determine whether the opcode should be
                 * INVOKE_DIRECT or INVOKE_SUPER. See vmspec-2 section 6
                 * on "invokespecial" as well as section 4.8.2 (7th
                 * bullet point) for the gory details.
                 */
                CstMethodRef ref = (CstMethodRef) cst;
                if (ref.isInstanceInit() ||
                    (ref.getDefiningClass() == method.getDefiningClass()) ||
                    !method.getAccSuper()) {
                    return RegOps.INVOKE_DIRECT;
                }
                return RegOps.INVOKE_SUPER;
            }
            case ByteOps.INVOKESTATIC: {
                return RegOps.INVOKE_STATIC;
            }
            case ByteOps.INVOKEINTERFACE: {
                return RegOps.INVOKE_INTERFACE;
            }
            case ByteOps.NEW: {
                return RegOps.NEW_INSTANCE;
            }
            case ByteOps.NEWARRAY:
            case ByteOps.ANEWARRAY: {
                return RegOps.NEW_ARRAY;
            }
            case ByteOps.ARRAYLENGTH: {
                return RegOps.ARRAY_LENGTH;
            }
            case ByteOps.ATHROW: {
                return RegOps.THROW;
            }
            case ByteOps.CHECKCAST: {
                return RegOps.CHECK_CAST;
            }
            case ByteOps.INSTANCEOF: {
                return RegOps.INSTANCE_OF;
            }
            case ByteOps.MONITORENTER: {
                return RegOps.MONITOR_ENTER;
            }
            case ByteOps.MONITOREXIT: {
                return RegOps.MONITOR_EXIT;
            }
        }

        throw new RuntimeException("shouldn't happen");
public booleanreturns()
Gets whether the block just processed ended with a return.

return
whether the block returns

        return returns;
public voidrun(Frame frame, int offset, int opcode)
{@inheritDoc}

        /*
         * This is the stack pointer after the opcode's arguments have been
         * popped.
         */
        int stackPointer = maxLocals + frame.getStack().size();

        // The sources have to be retrieved before super.run() gets called.
        RegisterSpecList sources = getSources(opcode, stackPointer);
        int sourceCount = sources.size();

        super.run(frame, offset, opcode);

        SourcePosition pos = method.makeSourcePosistion(offset);
        RegisterSpec localTarget = getLocalTarget();
        int destCount = resultCount();
        RegisterSpec dest;

        if (destCount == 0) {
            dest = null;
            switch (opcode) {
                case ByteOps.POP:
                case ByteOps.POP2: {
                    // These simply don't appear in the rop form.
                    return;
                }
            }
        } else if (localTarget != null) {
            dest = localTarget;
        } else if (destCount == 1) {
            dest = RegisterSpec.make(stackPointer, result(0));
        } else {
            /*
             * This clause only ever applies to the stack manipulation
             * ops that have results (that is, dup* and swap but not
             * pop*).
             *
             * What we do is first move all the source registers into
             * the "temporary stack" area defined for the method, and
             * then move stuff back down onto the main "stack" in the
             * arrangement specified by the stack op pattern.
             * 
             * Note: This code ends up emitting a lot of what will
             * turn out to be superfluous moves (e.g., moving back and
             * forth to the same local when doing a dup); however,
             * that makes this code a bit easier (and goodness knows
             * it doesn't need any extra complexity), and all the SSA
             * stuff is going to want to deal with this sort of
             * superfluous assignment anyway, so it should be a wash
             * in the end.
             */
            int scratchAt = ropper.getFirstTempStackReg();
            RegisterSpec[] scratchRegs = new RegisterSpec[sourceCount];

            for (int i = 0; i < sourceCount; i++) {
                RegisterSpec src = sources.get(i);
                TypeBearer type = src.getTypeBearer();
                RegisterSpec scratch = src.withReg(scratchAt);
                insns.add(new PlainInsn(Rops.opMove(type), pos, scratch, src));
                scratchRegs[i] = scratch;
                scratchAt += src.getCategory();
            }

            for (int pattern = getAuxInt(); pattern != 0; pattern >>= 4) {
                int which = (pattern & 0x0f) - 1;
                RegisterSpec scratch = scratchRegs[which];
                TypeBearer type = scratch.getTypeBearer();
                insns.add(new PlainInsn(Rops.opMove(type), pos,
                                        scratch.withReg(stackPointer),
                                        scratch));
                stackPointer += type.getType().getCategory();
            }
            return;
        }                

        TypeBearer destType = (dest != null) ? dest : Type.VOID;
        Constant cst = getAuxCst();
        int ropOpcode;
        Rop rop;
        Insn insn;

        if (opcode == ByteOps.MULTIANEWARRAY) {
            blockCanThrow = true;

            // Add the extra instructions for handling multianewarray.

            extraBlockCount = 6;

            /*
             * Add an array constructor for the int[] containing all the
             * dimensions.
             */
            RegisterSpec dimsReg = 
                RegisterSpec.make(dest.getNextReg(), Type.INT_ARRAY);
            rop = Rops.opFilledNewArray(Type.INT_ARRAY, sourceCount);
            insn = new ThrowingCstInsn(rop, pos, sources, catches,
                    CstType.INT_ARRAY);
            insns.add(insn);

            // Add a move-result for the new-filled-array
            rop = Rops.opMoveResult(Type.INT_ARRAY);
            insn = new PlainInsn(rop, pos, dimsReg, RegisterSpecList.EMPTY);
            insns.add(insn);

            /*
             * Add a const-class instruction for the specified array
             * class. 
             */

            /*
             * Remove as many dimensions from the originally specified
             * class as are given in the explicit list of dimensions,
             * so as to pass the right component class to the standard
             * Java library array constructor.
             */
            Type componentType = ((CstType) cst).getClassType();
            for (int i = 0; i < sourceCount; i++) {
                componentType = componentType.getComponentType();
            }

            RegisterSpec classReg =
                RegisterSpec.make(dest.getReg(), Type.CLASS);

            if (componentType.isPrimitive()) {
                /*
                 * The component type is primitive (e.g., int as opposed
                 * to Integer), so we have to fetch the corresponding
                 * TYPE class.
                 */
                CstFieldRef typeField =
                    CstFieldRef.forPrimitiveType(componentType);
                insn = new ThrowingCstInsn(Rops.GET_STATIC_OBJECT, pos,
                                           RegisterSpecList.EMPTY,
                                           catches, typeField);
            } else {
                /*
                 * The component type is an object type, so just make a
                 * normal class reference.
                 */
                insn = new ThrowingCstInsn(Rops.CONST_OBJECT, pos,
                                           RegisterSpecList.EMPTY, catches,
                                           new CstType(componentType));
            }

            insns.add(insn);

            // Add a move-result-pseudo for the get-static or const
            rop = Rops.opMoveResultPseudo(classReg.getType());
            insn = new PlainInsn(rop, pos, classReg, RegisterSpecList.EMPTY);
            insns.add(insn);

            /*
             * Add a call to the "multianewarray method," that is,
             * Array.newInstance(class, dims). Note: The result type
             * of newInstance() is Object, which is why the last
             * instruction in this sequence is a cast to the right
             * type for the original instruction.
             */

            RegisterSpec objectReg =
                RegisterSpec.make(dest.getReg(), Type.OBJECT);
            
            insn = new ThrowingCstInsn(
                    Rops.opInvokeStatic(MULTIANEWARRAY_METHOD.getPrototype()),
                    pos, RegisterSpecList.make(classReg, dimsReg),
                    catches, MULTIANEWARRAY_METHOD);
            insns.add(insn);

            // Add a move-result
            rop = Rops.opMoveResult(MULTIANEWARRAY_METHOD.getPrototype()
                    .getReturnType());
            insn = new PlainInsn(rop, pos, objectReg, RegisterSpecList.EMPTY);
            insns.add(insn);

            /*
             * And finally, set up for the remainder of this method to
             * add an appropriate cast.
             */

            opcode = ByteOps.CHECKCAST;
            sources = RegisterSpecList.make(objectReg);

        } else if (opcode == ByteOps.JSR) {
            // JSR has no Rop instruction
            hasJsr = true;
            return;
        } else if (opcode == ByteOps.RET) {
            try {
                returnAddress = (ReturnAddress)arg(0);
            } catch (ClassCastException ex) {
                throw new RuntimeException(
                        "Argument to RET was not a ReturnAddress", ex);
            }
            // RET has no Rop instruction.
            return;
        }

        ropOpcode = jopToRopOpcode(opcode, cst);

        rop = Rops.ropFor(ropOpcode, destType, sources, cst);

        Insn moveResult = null;
        if (dest != null && rop.isCallLike()) {
            // We're going to want to have a move-result in the next basic block
            extraBlockCount++;

            moveResult = new PlainInsn(
                    Rops.opMoveResult(((CstMethodRef) cst).getPrototype()
                    .getReturnType()), pos, dest, RegisterSpecList.EMPTY);

            dest = null;
        } else if (dest != null && rop.canThrow()) {
            // We're going to want to have a move-result-pseudo
            // in the next basic block
            extraBlockCount++;

            moveResult = new PlainInsn(
                    Rops.opMoveResultPseudo(dest.getTypeBearer()),
                    pos, dest, RegisterSpecList.EMPTY);

            dest = null;
        }
        if (ropOpcode == RegOps.NEW_ARRAY) {
            /*
             * In the original bytecode, this was either a primitive
             * array constructor "newarray" or an object array
             * constructor "anewarray". In the former case, there is
             * no explicit constant, and in the latter, the constant
             * is for the element type and not the array type. The rop
             * instruction form for both of these is supposed to be
             * the resulting array type, so we initialize / alter
             * "cst" here, accordingly. Conveniently enough, the rop
             * opcode already gets constructed with the proper array
             * type.
             */
            cst = CstType.intern(rop.getResult());
        } else if ((cst == null) && (sourceCount == 2)) {
            TypeBearer lastType = sources.get(1).getTypeBearer();

            if (lastType.isConstant()
                    && advice.hasConstantOperation(rop,
                    sources.get(0), sources.get(1))) {
                /*
                 * The target architecture has an instruction that can
                 * build in the constant found in the second argument,
                 * so pull it out of the sources and just use it as a
                 * constant here.
                 */
                cst = (Constant) lastType;
                sources = sources.withoutLast();
                rop = Rops.ropFor(ropOpcode, destType, sources, cst);
            }
        }

        SwitchList cases = getAuxCases();
        ArrayList<Constant> initValues = getInitValues();
        boolean canThrow = rop.canThrow();

        blockCanThrow |= canThrow;

        if (cases != null) {
            if (cases.size() == 0) {
                // It's a default-only switch statement. It can happen!
                insn = new PlainInsn(Rops.GOTO, pos, null,
                                     RegisterSpecList.EMPTY);
                primarySuccessorIndex = 0;
            } else {
                IntList values = cases.getValues();
                insn = new SwitchInsn(rop, pos, dest, sources, values);
                primarySuccessorIndex = values.size();
            }
        } else if (ropOpcode == RegOps.RETURN) {
            /*
             * Returns get turned into the combination of a move (if
             * non-void and if the return doesn't already mention
             * register 0) and a goto (to the return block).
             */
            if (sources.size() != 0) {
                RegisterSpec source = sources.get(0);
                TypeBearer type = source.getTypeBearer();
                if (source.getReg() != 0) {
                    insns.add(new PlainInsn(Rops.opMove(type), pos,
                                            RegisterSpec.make(0, type),
                                            source));
                }
            }
            insn = new PlainInsn(Rops.GOTO, pos, null, RegisterSpecList.EMPTY);
            primarySuccessorIndex = 0;
            updateReturnOp(rop, pos);
            returns = true;
        } else if (cst != null) {
            if (canThrow) {
                insn =
                    new ThrowingCstInsn(rop, pos, sources, catches, cst);
                catchesUsed = true;
                primarySuccessorIndex = catches.size();
            } else {
                insn = new PlainCstInsn(rop, pos, dest, sources, cst);
            }
        } else if (canThrow) {
            insn = new ThrowingInsn(rop, pos, sources, catches);
            catchesUsed = true;
            if (opcode == ByteOps.ATHROW) {
                /*
                 * The op athrow is the only one where it's possible
                 * to have non-empty successors and yet not have a
                 * primary successor.
                 */
                primarySuccessorIndex = -1;
            } else {
                primarySuccessorIndex = catches.size();
            }
        } else {
            insn = new PlainInsn(rop, pos, dest, sources);
        }

        insns.add(insn);

        if (moveResult != null) {
            insns.add(moveResult);
        }

        /*
         * If initValues is non-null, it means that the parser has seen a group
         * of compatible constant initialization bytecodes that are applied to
         * the current newarray. The action we take here is to convert these
         * initialization bytecodes into a single fill-array-data ROP which lays
         * out all the constant values in a table.
         */ 
        if (initValues != null) {
            extraBlockCount++;
            insn = new FillArrayDataInsn(Rops.FILL_ARRAY_DATA, pos,
                    RegisterSpecList.make(moveResult.getResult()), initValues,
                    cst);
            insns.add(insn);
        }
public voidstartBlock(com.android.dx.rop.type.TypeList catches)
Gets ready to start working on a new block. This will clear the {@link #insns} list, set {@link #catches}, reset whether it has been used, reset whether the block contains a return, and reset {@link #primarySuccessorIndex}.

        this.catches = catches;

        insns.clear();
        catchesUsed = false;
        returns = false;
        primarySuccessorIndex = 0;
        extraBlockCount = 0;
        blockCanThrow = false;
        hasJsr = false;
        returnAddress = null;
private voidupdateReturnOp(com.android.dx.rop.code.Rop op, com.android.dx.rop.code.SourcePosition pos)
Sets or updates the information about the return block.

param
op non-null; the opcode to use
param
pos non-null; the position to use

        if (op == null) {
            throw new NullPointerException("op == null");
        }

        if (pos == null) {
            throw new NullPointerException("pos == null");
        }

        if (returnOp == null) {
            returnOp = op;
            returnPosition = pos;
        } else {
            if (returnOp != op) {
                throw new SimException("return op mismatch: " + op + ", " +
                                       returnOp);
            }

            if (pos.getLine() > returnPosition.getLine()) {
                // Pick the largest line number to be the "canonical" return.
                returnPosition = pos;
            }
        }
public booleanwereCatchesUsed()
Gets whether {@link #catches} was used. This indicates that the last instruction in the block is one of the ones that can throw.

return
whether catches has been used

        return catchesUsed;