Examples with ArrayType soot.ArrayType used on opensource projects

Example 21 with ArrayType

use of soot.ArrayType in project robovm by robovm.

the class MarshalerLookup method findMarshalers.

public Marshaler findMarshalers(MarshalSite marshalSite) {
    soot.Type type = marshalSite.getType();
    SootClass sc = null;
    if (type instanceof RefType) {
        sc = ((RefType) type).getSootClass();
    } else if (type instanceof ArrayType && ((ArrayType) type).baseType instanceof RefType) {
        sc = ((RefType) ((ArrayType) type).baseType).getSootClass();
    }
    List<Marshaler> result = new ArrayList<>();
    Set<String> visited = new HashSet<>();
    Set<String> seen = new HashSet<>();
    if (sc != null) {
        findMarshalers(sc, result, visited, seen, false);
    }
    findMarshalers(marshalSite.method.getDeclaringClass(), result, visited, seen, searchBuiltins);
    for (Marshaler marshaler : result) {
        if (marshaler.canMarshal(marshalSite)) {
            return marshaler;
        }
    }
    return null;
}

Example 22 with ArrayType

use of soot.ArrayType in project soot by Sable.

the class TypeNode method array.

public TypeNode array() {
    if (array != null) {
        return array;
    }
    if (type instanceof ArrayType) {
        ArrayType atype = (ArrayType) type;
        array = hierarchy.typeNode(ArrayType.v(atype.baseType, atype.numDimensions + 1));
        return array;
    }
    if (type instanceof PrimType || type instanceof RefType) {
        array = hierarchy.typeNode(ArrayType.v(type, 1));
        return array;
    }
    throw new InternalTypingException();
}

Example 23 with ArrayType

use of soot.ArrayType in project soot by Sable.

the class UseChecker method caseAssignStmt.

public void caseAssignStmt(AssignStmt stmt) {
    Value lhs = stmt.getLeftOp();
    Value rhs = stmt.getRightOp();
    Type tlhs = null;
    if (lhs instanceof Local)
        tlhs = this.tg.get((Local) lhs);
    else if (lhs instanceof ArrayRef) {
        ArrayRef aref = (ArrayRef) lhs;
        Local base = (Local) aref.getBase();
        // Try to force Type integrity. The left side must agree on the
        // element type of the right side array reference.
        ArrayType at = null;
        Type tgType = this.tg.get(base);
        if (tgType instanceof ArrayType)
            at = (ArrayType) tgType;
        else {
            // is java.lang.Object
            if (tgType == Scene.v().getObjectType() && rhs instanceof Local) {
                Type rhsType = this.tg.get((Local) rhs);
                if (rhsType instanceof PrimType) {
                    if (defs == null) {
                        defs = LocalDefs.Factory.newLocalDefs(jb);
                        uses = LocalUses.Factory.newLocalUses(jb, defs);
                    }
                    // Check the original type of the array from the alloc site
                    for (Unit defU : defs.getDefsOfAt(base, stmt)) {
                        if (defU instanceof AssignStmt) {
                            AssignStmt defUas = (AssignStmt) defU;
                            if (defUas.getRightOp() instanceof NewArrayExpr) {
                                at = (ArrayType) defUas.getRightOp().getType();
                                break;
                            }
                        }
                    }
                }
            }
            if (at == null)
                at = tgType.makeArrayType();
        }
        tlhs = ((ArrayType) at).getElementType();
        this.handleArrayRef(aref, stmt);
        aref.setBase((Local) this.uv.visit(aref.getBase(), at, stmt));
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
        stmt.setLeftOp(this.uv.visit(lhs, tlhs, stmt));
    } else if (lhs instanceof FieldRef) {
        tlhs = ((FieldRef) lhs).getFieldRef().type();
        if (lhs instanceof InstanceFieldRef)
            this.handleInstanceFieldRef((InstanceFieldRef) lhs, stmt);
    }
    // They may have been changed above
    lhs = stmt.getLeftOp();
    rhs = stmt.getRightOp();
    if (rhs instanceof Local)
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    else if (rhs instanceof ArrayRef) {
        ArrayRef aref = (ArrayRef) rhs;
        Local base = (Local) aref.getBase();
        // try to force Type integrity
        ArrayType at = null;
        Type et = null;
        if (this.tg.get(base) instanceof ArrayType)
            at = (ArrayType) this.tg.get(base);
        else {
            Type bt = this.tg.get(base);
            // For some fixed type T, we assume that we can fix the array to T[].
            if (bt instanceof RefType || bt instanceof NullType) {
                RefType rt = bt instanceof NullType ? null : (RefType) bt;
                if (rt == null || rt.getSootClass().getName().equals("java.lang.Object") || rt.getSootClass().getName().equals("java.io.Serializable") || rt.getSootClass().getName().equals("java.lang.Cloneable")) {
                    if (defs == null) {
                        defs = LocalDefs.Factory.newLocalDefs(jb);
                        uses = LocalUses.Factory.newLocalUses(jb, defs);
                    }
                    outer: for (UnitValueBoxPair usePair : uses.getUsesOf(stmt)) {
                        Stmt useStmt = (Stmt) usePair.getUnit();
                        // from the callee's signature=
                        if (useStmt.containsInvokeExpr()) {
                            for (int i = 0; i < useStmt.getInvokeExpr().getArgCount(); i++) {
                                if (useStmt.getInvokeExpr().getArg(i) == usePair.getValueBox().getValue()) {
                                    et = useStmt.getInvokeExpr().getMethod().getParameterType(i);
                                    at = et.makeArrayType();
                                    break outer;
                                }
                            }
                        } else // if the other value is a primitive.
                        if (useStmt instanceof IfStmt) {
                            IfStmt ifStmt = (IfStmt) useStmt;
                            if (ifStmt.getCondition() instanceof EqExpr) {
                                EqExpr expr = (EqExpr) ifStmt.getCondition();
                                final Value other;
                                if (expr.getOp1() == usePair.getValueBox().getValue())
                                    other = expr.getOp2();
                                else
                                    other = expr.getOp1();
                                Type newEt = getTargetType(other);
                                if (newEt != null)
                                    et = newEt;
                            }
                        } else if (useStmt instanceof AssignStmt) {
                            // For binary expressions, we can look for type information in the
                            // other operands
                            AssignStmt useAssignStmt = (AssignStmt) useStmt;
                            if (useAssignStmt.getRightOp() instanceof BinopExpr) {
                                BinopExpr binOp = (BinopExpr) useAssignStmt.getRightOp();
                                final Value other;
                                if (binOp.getOp1() == usePair.getValueBox().getValue())
                                    other = binOp.getOp2();
                                else
                                    other = binOp.getOp1();
                                Type newEt = getTargetType(other);
                                if (newEt != null)
                                    et = newEt;
                            }
                        } else if (useStmt instanceof ReturnStmt) {
                            et = jb.getMethod().getReturnType();
                        }
                    }
                }
            }
            if (at == null)
                at = et.makeArrayType();
        }
        Type trhs = ((ArrayType) at).getElementType();
        this.handleArrayRef(aref, stmt);
        aref.setBase((Local) this.uv.visit(aref.getBase(), at, stmt));
        stmt.setRightOp(this.uv.visit(rhs, trhs, stmt));
    } else if (rhs instanceof InstanceFieldRef) {
        this.handleInstanceFieldRef((InstanceFieldRef) rhs, stmt);
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof BinopExpr)
        this.handleBinopExpr((BinopExpr) rhs, stmt, tlhs);
    else if (rhs instanceof InvokeExpr) {
        this.handleInvokeExpr((InvokeExpr) rhs, stmt);
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof CastExpr)
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    else if (rhs instanceof InstanceOfExpr) {
        InstanceOfExpr ioe = (InstanceOfExpr) rhs;
        ioe.setOp(this.uv.visit(ioe.getOp(), RefType.v("java.lang.Object"), stmt));
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof NewArrayExpr) {
        NewArrayExpr nae = (NewArrayExpr) rhs;
        nae.setSize(this.uv.visit(nae.getSize(), IntType.v(), stmt));
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof NewMultiArrayExpr) {
        NewMultiArrayExpr nmae = (NewMultiArrayExpr) rhs;
        for (int i = 0; i < nmae.getSizeCount(); i++) nmae.setSize(i, this.uv.visit(nmae.getSize(i), IntType.v(), stmt));
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof LengthExpr) {
        stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
    } else if (rhs instanceof NegExpr) {
        ((NegExpr) rhs).setOp(this.uv.visit(((NegExpr) rhs).getOp(), tlhs, stmt));
    } else if (rhs instanceof Constant)
        if (!(rhs instanceof NullConstant))
            stmt.setRightOp(this.uv.visit(rhs, tlhs, stmt));
}

Example 24 with ArrayType

use of soot.ArrayType in project soot by Sable.

the class ConstraintChecker method caseAssignStmt.

public void caseAssignStmt(AssignStmt stmt) {
    Value l = stmt.getLeftOp();
    Value r = stmt.getRightOp();
    TypeNode left = null;
    TypeNode right = null;
    if (l instanceof ArrayRef) {
        ArrayRef ref = (ArrayRef) l;
        Type baset = ((Local) ref.getBase()).getType();
        if (baset instanceof ArrayType) {
            ArrayType base = (ArrayType) baset;
            Value index = ref.getIndex();
            if ((base.numDimensions == 1) && (base.baseType instanceof IntegerType)) {
                left = ClassHierarchy.v().typeNode(base.baseType);
            }
            if (index instanceof Local) {
                if (!ClassHierarchy.v().typeNode(((Local) index).getType()).hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        ref.setIndex(insertCast((Local) index, IntType.v(), stmt));
                    } else {
                        error("Type Error(5)");
                    }
                }
            }
        }
    } else if (l instanceof Local) {
        if (((Local) l).getType() instanceof IntegerType) {
            left = ClassHierarchy.v().typeNode(((Local) l).getType());
        }
    } else if (l instanceof InstanceFieldRef) {
        InstanceFieldRef ref = (InstanceFieldRef) l;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            left = ClassHierarchy.v().typeNode(ref.getFieldRef().type());
        }
    } else if (l instanceof StaticFieldRef) {
        StaticFieldRef ref = (StaticFieldRef) l;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            left = ClassHierarchy.v().typeNode(ref.getFieldRef().type());
        }
    } else {
        throw new RuntimeException("Unhandled assignment left hand side type: " + l.getClass());
    }
    if (r instanceof ArrayRef) {
        ArrayRef ref = (ArrayRef) r;
        Type baset = ((Local) ref.getBase()).getType();
        if (!(baset instanceof NullType)) {
            ArrayType base = (ArrayType) baset;
            Value index = ref.getIndex();
            if ((base.numDimensions == 1) && (base.baseType instanceof IntegerType)) {
                right = ClassHierarchy.v().typeNode(base.baseType);
            }
            if (index instanceof Local) {
                if (!ClassHierarchy.v().typeNode(((Local) index).getType()).hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        ref.setIndex(insertCast((Local) index, IntType.v(), stmt));
                    } else {
                        error("Type Error(6)");
                    }
                }
            }
        }
    } else if (r instanceof DoubleConstant) {
    } else if (r instanceof FloatConstant) {
    } else if (r instanceof IntConstant) {
        int value = ((IntConstant) r).value;
        if (value < -32768) {
            right = ClassHierarchy.v().INT;
        } else if (value < -128) {
            right = ClassHierarchy.v().SHORT;
        } else if (value < 0) {
            right = ClassHierarchy.v().BYTE;
        } else if (value < 2) {
            right = ClassHierarchy.v().R0_1;
        } else if (value < 128) {
            right = ClassHierarchy.v().R0_127;
        } else if (value < 32768) {
            right = ClassHierarchy.v().R0_32767;
        } else if (value < 65536) {
            right = ClassHierarchy.v().CHAR;
        } else {
            right = ClassHierarchy.v().INT;
        }
    } else if (r instanceof LongConstant) {
    } else if (r instanceof NullConstant) {
    } else if (r instanceof StringConstant) {
    } else if (r instanceof ClassConstant) {
    } else if (r instanceof BinopExpr) {
        // ******** BINOP EXPR ********
        BinopExpr be = (BinopExpr) r;
        Value lv = be.getOp1();
        Value rv = be.getOp2();
        TypeNode lop = null;
        TypeNode rop = null;
        // ******** LEFT ********
        if (lv instanceof Local) {
            if (((Local) lv).getType() instanceof IntegerType) {
                lop = ClassHierarchy.v().typeNode(((Local) lv).getType());
            }
        } else if (lv instanceof DoubleConstant) {
        } else if (lv instanceof FloatConstant) {
        } else if (lv instanceof IntConstant) {
            int value = ((IntConstant) lv).value;
            if (value < -32768) {
                lop = ClassHierarchy.v().INT;
            } else if (value < -128) {
                lop = ClassHierarchy.v().SHORT;
            } else if (value < 0) {
                lop = ClassHierarchy.v().BYTE;
            } else if (value < 2) {
                lop = ClassHierarchy.v().R0_1;
            } else if (value < 128) {
                lop = ClassHierarchy.v().R0_127;
            } else if (value < 32768) {
                lop = ClassHierarchy.v().R0_32767;
            } else if (value < 65536) {
                lop = ClassHierarchy.v().CHAR;
            } else {
                lop = ClassHierarchy.v().INT;
            }
        } else if (lv instanceof LongConstant) {
        } else if (lv instanceof NullConstant) {
        } else if (lv instanceof StringConstant) {
        } else if (lv instanceof ClassConstant) {
        } else {
            throw new RuntimeException("Unhandled binary expression left operand type: " + lv.getClass());
        }
        // ******** RIGHT ********
        if (rv instanceof Local) {
            if (((Local) rv).getType() instanceof IntegerType) {
                rop = ClassHierarchy.v().typeNode(((Local) rv).getType());
            }
        } else if (rv instanceof DoubleConstant) {
        } else if (rv instanceof FloatConstant) {
        } else if (rv instanceof IntConstant) {
            int value = ((IntConstant) rv).value;
            if (value < -32768) {
                rop = ClassHierarchy.v().INT;
            } else if (value < -128) {
                rop = ClassHierarchy.v().SHORT;
            } else if (value < 0) {
                rop = ClassHierarchy.v().BYTE;
            } else if (value < 2) {
                rop = ClassHierarchy.v().R0_1;
            } else if (value < 128) {
                rop = ClassHierarchy.v().R0_127;
            } else if (value < 32768) {
                rop = ClassHierarchy.v().R0_32767;
            } else if (value < 65536) {
                rop = ClassHierarchy.v().CHAR;
            } else {
                rop = ClassHierarchy.v().INT;
            }
        } else if (rv instanceof LongConstant) {
        } else if (rv instanceof NullConstant) {
        } else if (rv instanceof StringConstant) {
        } else if (rv instanceof ClassConstant) {
        } else {
            throw new RuntimeException("Unhandled binary expression right operand type: " + rv.getClass());
        }
        if ((be instanceof AddExpr) || (be instanceof SubExpr) || (be instanceof MulExpr) || (be instanceof DivExpr) || (be instanceof RemExpr)) {
            if (lop != null && rop != null) {
                if (!lop.hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        be.setOp1(insertCast(be.getOp1(), getTypeForCast(lop), IntType.v(), stmt));
                    } else {
                        error("Type Error(7)");
                    }
                }
                if (!rop.hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        be.setOp2(insertCast(be.getOp2(), getTypeForCast(rop), IntType.v(), stmt));
                    } else {
                        error("Type Error(8)");
                    }
                }
            }
            right = ClassHierarchy.v().INT;
        } else if ((be instanceof AndExpr) || (be instanceof OrExpr) || (be instanceof XorExpr)) {
            if (lop != null && rop != null) {
                TypeNode lca = lop.lca_1(rop);
                if (lca == ClassHierarchy.v().TOP) {
                    if (fix) {
                        if (!lop.hasAncestor_1(ClassHierarchy.v().INT)) {
                            be.setOp1(insertCast(be.getOp1(), getTypeForCast(lop), getTypeForCast(rop), stmt));
                            lca = rop;
                        }
                        if (!rop.hasAncestor_1(ClassHierarchy.v().INT)) {
                            be.setOp2(insertCast(be.getOp2(), getTypeForCast(rop), getTypeForCast(lop), stmt));
                            lca = lop;
                        }
                    } else {
                        error("Type Error(11)");
                    }
                }
                right = lca;
            }
        } else if (be instanceof ShlExpr) {
            if (lop != null) {
                if (!lop.hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        be.setOp1(insertCast(be.getOp1(), getTypeForCast(lop), IntType.v(), stmt));
                    } else {
                        error("Type Error(9)");
                    }
                }
            }
            if (!rop.hasAncestor_1(ClassHierarchy.v().INT)) {
                if (fix) {
                    be.setOp2(insertCast(be.getOp2(), getTypeForCast(rop), IntType.v(), stmt));
                } else {
                    error("Type Error(10)");
                }
            }
            right = (lop == null) ? null : ClassHierarchy.v().INT;
        } else if ((be instanceof ShrExpr) || (be instanceof UshrExpr)) {
            if (lop != null) {
                if (!lop.hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        be.setOp1(insertCast(be.getOp1(), getTypeForCast(lop), ByteType.v(), stmt));
                        lop = ClassHierarchy.v().BYTE;
                    } else {
                        error("Type Error(9)");
                    }
                }
            }
            if (!rop.hasAncestor_1(ClassHierarchy.v().INT)) {
                if (fix) {
                    be.setOp2(insertCast(be.getOp2(), getTypeForCast(rop), IntType.v(), stmt));
                } else {
                    error("Type Error(10)");
                }
            }
            right = lop;
        } else if ((be instanceof CmpExpr) || (be instanceof CmpgExpr) || (be instanceof CmplExpr)) {
            right = ClassHierarchy.v().BYTE;
        } else if ((be instanceof EqExpr) || (be instanceof GeExpr) || (be instanceof GtExpr) || (be instanceof LeExpr) || (be instanceof LtExpr) || (be instanceof NeExpr)) {
            if (rop != null) {
                TypeNode lca = lop.lca_1(rop);
                if (lca == ClassHierarchy.v().TOP) {
                    if (fix) {
                        if (!lop.hasAncestor_1(ClassHierarchy.v().INT)) {
                            be.setOp1(insertCast(be.getOp1(), getTypeForCast(lop), getTypeForCast(rop), stmt));
                        }
                        if (!rop.hasAncestor_1(ClassHierarchy.v().INT)) {
                            be.setOp2(insertCast(be.getOp2(), getTypeForCast(rop), getTypeForCast(lop), stmt));
                        }
                    } else {
                        error("Type Error(11)");
                    }
                }
            }
            right = ClassHierarchy.v().BOOLEAN;
        } else {
            throw new RuntimeException("Unhandled binary expression type: " + be.getClass());
        }
    } else if (r instanceof CastExpr) {
        CastExpr ce = (CastExpr) r;
        if (ce.getCastType() instanceof IntegerType) {
            right = ClassHierarchy.v().typeNode(ce.getCastType());
        }
    } else if (r instanceof InstanceOfExpr) {
        right = ClassHierarchy.v().BOOLEAN;
    } else if (r instanceof InvokeExpr) {
        InvokeExpr ie = (InvokeExpr) r;
        handleInvokeExpr(ie, stmt);
        if (ie.getMethodRef().returnType() instanceof IntegerType) {
            right = ClassHierarchy.v().typeNode(ie.getMethodRef().returnType());
        }
    } else if (r instanceof NewArrayExpr) {
        NewArrayExpr nae = (NewArrayExpr) r;
        Value size = nae.getSize();
        if (size instanceof Local) {
            if (!ClassHierarchy.v().typeNode(((Local) size).getType()).hasAncestor_1(ClassHierarchy.v().INT)) {
                if (fix) {
                    nae.setSize(insertCast((Local) size, IntType.v(), stmt));
                } else {
                    error("Type Error(12)");
                }
            }
        }
    } else if (r instanceof NewExpr) {
    } else if (r instanceof NewMultiArrayExpr) {
        NewMultiArrayExpr nmae = (NewMultiArrayExpr) r;
        for (int i = 0; i < nmae.getSizeCount(); i++) {
            Value size = nmae.getSize(i);
            if (size instanceof Local) {
                if (!ClassHierarchy.v().typeNode(((Local) size).getType()).hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        nmae.setSize(i, insertCast((Local) size, IntType.v(), stmt));
                    } else {
                        error("Type Error(13)");
                    }
                }
            }
        }
    } else if (r instanceof LengthExpr) {
        right = ClassHierarchy.v().INT;
    } else if (r instanceof NegExpr) {
        NegExpr ne = (NegExpr) r;
        if (ne.getOp() instanceof Local) {
            Local local = (Local) ne.getOp();
            if (local.getType() instanceof IntegerType) {
                TypeNode ltype = ClassHierarchy.v().typeNode(local.getType());
                if (!ltype.hasAncestor_1(ClassHierarchy.v().INT)) {
                    if (fix) {
                        ne.setOp(insertCast(local, IntType.v(), stmt));
                        ltype = ClassHierarchy.v().BYTE;
                    } else {
                        error("Type Error(14)");
                    }
                }
                right = (ltype == ClassHierarchy.v().CHAR) ? ClassHierarchy.v().INT : ltype;
            }
        } else if (ne.getOp() instanceof DoubleConstant) {
        } else if (ne.getOp() instanceof FloatConstant) {
        } else if (ne.getOp() instanceof IntConstant) {
            right = ClassHierarchy.v().INT;
        } else if (ne.getOp() instanceof LongConstant) {
        } else {
            throw new RuntimeException("Unhandled neg expression operand type: " + ne.getOp().getClass());
        }
    } else if (r instanceof Local) {
        Local local = (Local) r;
        if (local.getType() instanceof IntegerType) {
            right = ClassHierarchy.v().typeNode(local.getType());
        }
    } else if (r instanceof InstanceFieldRef) {
        InstanceFieldRef ref = (InstanceFieldRef) r;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            right = ClassHierarchy.v().typeNode(ref.getFieldRef().type());
        }
    } else if (r instanceof StaticFieldRef) {
        StaticFieldRef ref = (StaticFieldRef) r;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            right = ClassHierarchy.v().typeNode(ref.getFieldRef().type());
        }
    } else {
        throw new RuntimeException("Unhandled assignment right hand side type: " + r.getClass());
    }
    if (left != null && right != null) {
        if (!right.hasAncestor_1(left)) {
            if (fix) {
                stmt.setRightOp(insertCast(stmt.getRightOp(), getTypeForCast(right), getTypeForCast(left), stmt));
            } else {
                error("Type Error(15)");
            }
        }
    }
}

Example 25 with ArrayType

use of soot.ArrayType in project soot by Sable.

the class BytecodeHierarchy method lcas_.

public static Collection<Type> lcas_(Type a, Type b) {
    if (TypeResolver.typesEqual(a, b))
        return Collections.<Type>singletonList(a);
    else if (a instanceof BottomType)
        return Collections.<Type>singletonList(b);
    else if (b instanceof BottomType)
        return Collections.<Type>singletonList(a);
    else if (a instanceof IntegerType && b instanceof IntegerType)
        return Collections.<Type>singletonList(IntType.v());
    else // Implicit type widening: Integer+Float -> Float
    if (a instanceof IntegerType && b instanceof FloatType)
        return Collections.<Type>singletonList(FloatType.v());
    else if (b instanceof IntegerType && a instanceof FloatType)
        return Collections.<Type>singletonList(FloatType.v());
    else // Disallow type sharing for primitives in general
    if (a instanceof PrimType || b instanceof PrimType)
        return Collections.<Type>emptyList();
    else // Null reference handling
    if (a instanceof NullType)
        return Collections.<Type>singletonList(b);
    else if (b instanceof NullType)
        return Collections.<Type>singletonList(a);
    else // a and b are both ArrayType or RefType
    if (a instanceof ArrayType && b instanceof ArrayType) {
        Type eta = ((ArrayType) a).getElementType(), etb = ((ArrayType) b).getElementType();
        Collection<Type> ts;
        // Primitive arrays are not covariant but all other arrays are
        if (eta instanceof PrimType || etb instanceof PrimType)
            ts = Collections.<Type>emptyList();
        else
            ts = lcas_(eta, etb);
        LinkedList<Type> r = new LinkedList<Type>();
        if (ts.isEmpty()) {
            // From Java Language Spec 2nd ed., Chapter 10, Arrays
            r.add(RefType.v("java.lang.Object"));
            r.add(RefType.v("java.io.Serializable"));
            r.add(RefType.v("java.lang.Cloneable"));
        } else
            for (Type t : ts) r.add(t.makeArrayType());
        return r;
    } else if (a instanceof ArrayType || b instanceof ArrayType) {
        Type rt;
        if (a instanceof ArrayType)
            rt = b;
        else
            rt = a;
        /* If the reference type implements Serializable or Cloneable then 
			these are the least common supertypes, otherwise the only one is 
			Object. */
        LinkedList<Type> r = new LinkedList<Type>();
        /* Do not consider Object to be a subtype of Serializable or Cloneable
			(it can appear this way if phantom-refs is enabled and rt.jar is not
			available) otherwise an infinite loop can result. */
        if (!TypeResolver.typesEqual(RefType.v("java.lang.Object"), rt)) {
            if (ancestor_(RefType.v("java.io.Serializable"), rt))
                r.add(RefType.v("java.io.Serializable"));
            if (ancestor_(RefType.v("java.lang.Cloneable"), rt))
                r.add(RefType.v("java.lang.Cloneable"));
        }
        if (r.isEmpty())
            r.add(RefType.v("java.lang.Object"));
        return r;
    } else // a and b are both RefType
    {
        Collection<AncestryTreeNode> treea = buildAncestryTree((RefType) a), treeb = buildAncestryTree((RefType) b);
        LinkedList<Type> r = new LinkedList<Type>();
        for (AncestryTreeNode nodea : treea) for (AncestryTreeNode nodeb : treeb) {
            RefType t = leastCommonNode(nodea, nodeb);
            boolean least = true;
            for (ListIterator<Type> i = r.listIterator(); i.hasNext(); ) {
                Type t_ = i.next();
                if (ancestor_(t, t_)) {
                    least = false;
                    break;
                }
                if (ancestor_(t_, t))
                    i.remove();
            }
            if (least)
                r.add(t);
        }
        // syed - 05/06/2009
        if (r.isEmpty())
            r.add(RefType.v("java.lang.Object"));
        return r;
    }
}