Examples with NullConstant soot.jimple.NullConstant used on opensource projects

Example 1 with NullConstant

use of soot.jimple.NullConstant in project soot by Sable.

the class ConstraintCollector method caseAssignStmt.

public void caseAssignStmt(AssignStmt stmt) {
    Value l = stmt.getLeftOp();
    Value r = stmt.getRightOp();
    TypeVariable left = null;
    TypeVariable right = null;
    if (l instanceof ArrayRef) {
        ArrayRef ref = (ArrayRef) l;
        Value base = ref.getBase();
        Value index = ref.getIndex();
        TypeVariable baseType = resolver.typeVariable((Local) base);
        baseType.makeElement();
        left = baseType.element();
        if (index instanceof Local) {
            if (uses) {
                resolver.typeVariable((Local) index).addParent(resolver.typeVariable(IntType.v()));
            }
        }
    } else if (l instanceof Local) {
        left = resolver.typeVariable((Local) l);
    } else if (l instanceof InstanceFieldRef) {
        InstanceFieldRef ref = (InstanceFieldRef) l;
        if (uses) {
            TypeVariable baseType = resolver.typeVariable((Local) ref.getBase());
            baseType.addParent(resolver.typeVariable(ref.getField().getDeclaringClass()));
            left = resolver.typeVariable(ref.getField().getType());
        }
    } else if (l instanceof StaticFieldRef) {
        if (uses) {
            StaticFieldRef ref = (StaticFieldRef) l;
            left = resolver.typeVariable(ref.getField().getType());
        }
    } else {
        throw new RuntimeException("Unhandled assignment left hand side type: " + l.getClass());
    }
    if (r instanceof ArrayRef) {
        ArrayRef ref = (ArrayRef) r;
        Value base = ref.getBase();
        Value index = ref.getIndex();
        TypeVariable baseType = resolver.typeVariable((Local) base);
        baseType.makeElement();
        right = baseType.element();
        if (index instanceof Local) {
            if (uses) {
                resolver.typeVariable((Local) index).addParent(resolver.typeVariable(IntType.v()));
            }
        }
    } else if (r instanceof DoubleConstant) {
        right = resolver.typeVariable(DoubleType.v());
    } else if (r instanceof FloatConstant) {
        right = resolver.typeVariable(FloatType.v());
    } else if (r instanceof IntConstant) {
        right = resolver.typeVariable(IntType.v());
    } else if (r instanceof LongConstant) {
        right = resolver.typeVariable(LongType.v());
    } else if (r instanceof NullConstant) {
        right = resolver.typeVariable(NullType.v());
    } else if (r instanceof StringConstant) {
        right = resolver.typeVariable(RefType.v("java.lang.String"));
    } else if (r instanceof ClassConstant) {
        right = resolver.typeVariable(RefType.v("java.lang.Class"));
    } else if (r instanceof BinopExpr) {
        // ******** BINOP EXPR ********
        BinopExpr be = (BinopExpr) r;
        Value lv = be.getOp1();
        Value rv = be.getOp2();
        TypeVariable lop;
        TypeVariable rop;
        // ******** LEFT ********
        if (lv instanceof Local) {
            lop = resolver.typeVariable((Local) lv);
        } else if (lv instanceof DoubleConstant) {
            lop = resolver.typeVariable(DoubleType.v());
        } else if (lv instanceof FloatConstant) {
            lop = resolver.typeVariable(FloatType.v());
        } else if (lv instanceof IntConstant) {
            lop = resolver.typeVariable(IntType.v());
        } else if (lv instanceof LongConstant) {
            lop = resolver.typeVariable(LongType.v());
        } else if (lv instanceof NullConstant) {
            lop = resolver.typeVariable(NullType.v());
        } else if (lv instanceof StringConstant) {
            lop = resolver.typeVariable(RefType.v("java.lang.String"));
        } else if (lv instanceof ClassConstant) {
            lop = resolver.typeVariable(RefType.v("java.lang.Class"));
        } else {
            throw new RuntimeException("Unhandled binary expression left operand type: " + lv.getClass());
        }
        // ******** RIGHT ********
        if (rv instanceof Local) {
            rop = resolver.typeVariable((Local) rv);
        } else if (rv instanceof DoubleConstant) {
            rop = resolver.typeVariable(DoubleType.v());
        } else if (rv instanceof FloatConstant) {
            rop = resolver.typeVariable(FloatType.v());
        } else if (rv instanceof IntConstant) {
            rop = resolver.typeVariable(IntType.v());
        } else if (rv instanceof LongConstant) {
            rop = resolver.typeVariable(LongType.v());
        } else if (rv instanceof NullConstant) {
            rop = resolver.typeVariable(NullType.v());
        } else if (rv instanceof StringConstant) {
            rop = resolver.typeVariable(RefType.v("java.lang.String"));
        } else if (rv instanceof ClassConstant) {
            rop = resolver.typeVariable(RefType.v("java.lang.Class"));
        } 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) || (be instanceof AndExpr) || (be instanceof OrExpr) || (be instanceof XorExpr)) {
            if (uses) {
                TypeVariable common = resolver.typeVariable();
                rop.addParent(common);
                lop.addParent(common);
            }
            if (left != null) {
                rop.addParent(left);
                lop.addParent(left);
            }
        } else if ((be instanceof ShlExpr) || (be instanceof ShrExpr) || (be instanceof UshrExpr)) {
            if (uses) {
                rop.addParent(resolver.typeVariable(IntType.v()));
            }
            right = lop;
        } else if ((be instanceof CmpExpr) || (be instanceof CmpgExpr) || (be instanceof CmplExpr) || (be instanceof EqExpr) || (be instanceof GeExpr) || (be instanceof GtExpr) || (be instanceof LeExpr) || (be instanceof LtExpr) || (be instanceof NeExpr)) {
            if (uses) {
                TypeVariable common = resolver.typeVariable();
                rop.addParent(common);
                lop.addParent(common);
            }
            right = resolver.typeVariable(IntType.v());
        } else {
            throw new RuntimeException("Unhandled binary expression type: " + be.getClass());
        }
    } else if (r instanceof CastExpr) {
        CastExpr ce = (CastExpr) r;
        right = resolver.typeVariable(ce.getCastType());
    } else if (r instanceof InstanceOfExpr) {
        right = resolver.typeVariable(IntType.v());
    } else if (r instanceof InvokeExpr) {
        InvokeExpr ie = (InvokeExpr) r;
        handleInvokeExpr(ie);
        right = resolver.typeVariable(ie.getMethodRef().returnType());
    } else if (r instanceof NewArrayExpr) {
        NewArrayExpr nae = (NewArrayExpr) r;
        Type baseType = nae.getBaseType();
        if (baseType instanceof ArrayType) {
            right = resolver.typeVariable(ArrayType.v(((ArrayType) baseType).baseType, ((ArrayType) baseType).numDimensions + 1));
        } else {
            right = resolver.typeVariable(ArrayType.v(baseType, 1));
        }
        if (uses) {
            Value size = nae.getSize();
            if (size instanceof Local) {
                TypeVariable var = resolver.typeVariable((Local) size);
                var.addParent(resolver.typeVariable(IntType.v()));
            }
        }
    } else if (r instanceof NewExpr) {
        NewExpr na = (NewExpr) r;
        right = resolver.typeVariable(na.getBaseType());
    } else if (r instanceof NewMultiArrayExpr) {
        NewMultiArrayExpr nmae = (NewMultiArrayExpr) r;
        right = resolver.typeVariable(nmae.getBaseType());
        if (uses) {
            for (int i = 0; i < nmae.getSizeCount(); i++) {
                Value size = nmae.getSize(i);
                if (size instanceof Local) {
                    TypeVariable var = resolver.typeVariable((Local) size);
                    var.addParent(resolver.typeVariable(IntType.v()));
                }
            }
        }
    } else if (r instanceof LengthExpr) {
        LengthExpr le = (LengthExpr) r;
        if (uses) {
            if (le.getOp() instanceof Local) {
                resolver.typeVariable((Local) le.getOp()).makeElement();
            }
        }
        right = resolver.typeVariable(IntType.v());
    } else if (r instanceof NegExpr) {
        NegExpr ne = (NegExpr) r;
        if (ne.getOp() instanceof Local) {
            right = resolver.typeVariable((Local) ne.getOp());
        } else if (ne.getOp() instanceof DoubleConstant) {
            right = resolver.typeVariable(DoubleType.v());
        } else if (ne.getOp() instanceof FloatConstant) {
            right = resolver.typeVariable(FloatType.v());
        } else if (ne.getOp() instanceof IntConstant) {
            right = resolver.typeVariable(IntType.v());
        } else if (ne.getOp() instanceof LongConstant) {
            right = resolver.typeVariable(LongType.v());
        } else {
            throw new RuntimeException("Unhandled neg expression operand type: " + ne.getOp().getClass());
        }
    } else if (r instanceof Local) {
        right = resolver.typeVariable((Local) r);
    } else if (r instanceof InstanceFieldRef) {
        InstanceFieldRef ref = (InstanceFieldRef) r;
        if (uses) {
            TypeVariable baseType = resolver.typeVariable((Local) ref.getBase());
            baseType.addParent(resolver.typeVariable(ref.getField().getDeclaringClass()));
        }
        right = resolver.typeVariable(ref.getField().getType());
    } else if (r instanceof StaticFieldRef) {
        StaticFieldRef ref = (StaticFieldRef) r;
        right = resolver.typeVariable(ref.getField().getType());
    } else {
        throw new RuntimeException("Unhandled assignment right hand side type: " + r.getClass());
    }
    if (left != null && right != null) {
        right.addParent(left);
    }
}

Example 2 with NullConstant

use of soot.jimple.NullConstant in project soot by Sable.

the class ConstraintCollector method caseIfStmt.

public void caseIfStmt(IfStmt stmt) {
    if (uses) {
        ConditionExpr cond = (ConditionExpr) stmt.getCondition();
        BinopExpr expr = cond;
        Value lv = expr.getOp1();
        Value rv = expr.getOp2();
        TypeVariable lop;
        TypeVariable rop;
        // ******** LEFT ********
        if (lv instanceof Local) {
            lop = resolver.typeVariable((Local) lv);
        } else if (lv instanceof DoubleConstant) {
            lop = resolver.typeVariable(DoubleType.v());
        } else if (lv instanceof FloatConstant) {
            lop = resolver.typeVariable(FloatType.v());
        } else if (lv instanceof IntConstant) {
            lop = resolver.typeVariable(IntType.v());
        } else if (lv instanceof LongConstant) {
            lop = resolver.typeVariable(LongType.v());
        } else if (lv instanceof NullConstant) {
            lop = resolver.typeVariable(NullType.v());
        } else if (lv instanceof StringConstant) {
            lop = resolver.typeVariable(RefType.v("java.lang.String"));
        } else if (lv instanceof ClassConstant) {
            lop = resolver.typeVariable(RefType.v("java.lang.Class"));
        } else {
            throw new RuntimeException("Unhandled binary expression left operand type: " + lv.getClass());
        }
        // ******** RIGHT ********
        if (rv instanceof Local) {
            rop = resolver.typeVariable((Local) rv);
        } else if (rv instanceof DoubleConstant) {
            rop = resolver.typeVariable(DoubleType.v());
        } else if (rv instanceof FloatConstant) {
            rop = resolver.typeVariable(FloatType.v());
        } else if (rv instanceof IntConstant) {
            rop = resolver.typeVariable(IntType.v());
        } else if (rv instanceof LongConstant) {
            rop = resolver.typeVariable(LongType.v());
        } else if (rv instanceof NullConstant) {
            rop = resolver.typeVariable(NullType.v());
        } else if (rv instanceof StringConstant) {
            rop = resolver.typeVariable(RefType.v("java.lang.String"));
        } else if (rv instanceof ClassConstant) {
            rop = resolver.typeVariable(RefType.v("java.lang.Class"));
        } else {
            throw new RuntimeException("Unhandled binary expression right operand type: " + rv.getClass());
        }
        TypeVariable common = resolver.typeVariable();
        rop.addParent(common);
        lop.addParent(common);
    }
}

Example 3 with NullConstant

use of soot.jimple.NullConstant in project soot by Sable.

the class ConstraintCollector method caseAssignStmt.

public void caseAssignStmt(AssignStmt stmt) {
    Value l = stmt.getLeftOp();
    Value r = stmt.getRightOp();
    TypeVariable left = null;
    TypeVariable 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 (uses) {
                if ((base.numDimensions == 1) && (base.baseType instanceof IntegerType)) {
                    left = resolver.typeVariable(base.baseType);
                }
                if (index instanceof Local) {
                    resolver.typeVariable((Local) index).addParent(resolver.INT);
                }
            }
        }
    } else if (l instanceof Local) {
        if (((Local) l).getType() instanceof IntegerType) {
            left = resolver.typeVariable((Local) l);
        }
    } else if (l instanceof InstanceFieldRef) {
        if (uses) {
            InstanceFieldRef ref = (InstanceFieldRef) l;
            Type fieldType = ref.getFieldRef().type();
            if (fieldType instanceof IntegerType) {
                left = resolver.typeVariable(ref.getFieldRef().type());
            }
        }
    } else if (l instanceof StaticFieldRef) {
        if (uses) {
            StaticFieldRef ref = (StaticFieldRef) l;
            Type fieldType = ref.getFieldRef().type();
            if (fieldType instanceof IntegerType) {
                left = resolver.typeVariable(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)) {
            Value index = ref.getIndex();
            // Be careful, dex can do some weird object/array casting
            if (baset instanceof ArrayType) {
                ArrayType base = (ArrayType) baset;
                if ((base.numDimensions == 1) && (base.baseType instanceof IntegerType)) {
                    right = resolver.typeVariable(base.baseType);
                }
            } else if (baset instanceof IntegerType)
                right = resolver.typeVariable(baset);
            if (uses)
                if (index instanceof Local)
                    resolver.typeVariable((Local) index).addParent(resolver.INT);
        }
    } else if (r instanceof DoubleConstant) {
    } else if (r instanceof FloatConstant) {
    } else if (r instanceof IntConstant) {
        int value = ((IntConstant) r).value;
        if (value < -32768) {
            right = resolver.INT;
        } else if (value < -128) {
            right = resolver.SHORT;
        } else if (value < 0) {
            right = resolver.BYTE;
        } else if (value < 2) {
            right = resolver.R0_1;
        } else if (value < 128) {
            right = resolver.R0_127;
        } else if (value < 32768) {
            right = resolver.R0_32767;
        } else if (value < 65536) {
            right = resolver.CHAR;
        } else {
            right = resolver.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();
        TypeVariable lop = null;
        TypeVariable rop = null;
        // ******** LEFT ********
        if (lv instanceof Local) {
            if (((Local) lv).getType() instanceof IntegerType) {
                lop = resolver.typeVariable((Local) lv);
            }
        } else if (lv instanceof DoubleConstant) {
        } else if (lv instanceof FloatConstant) {
        } else if (lv instanceof IntConstant) {
            int value = ((IntConstant) lv).value;
            if (value < -32768) {
                lop = resolver.INT;
            } else if (value < -128) {
                lop = resolver.SHORT;
            } else if (value < 0) {
                lop = resolver.BYTE;
            } else if (value < 2) {
                lop = resolver.R0_1;
            } else if (value < 128) {
                lop = resolver.R0_127;
            } else if (value < 32768) {
                lop = resolver.R0_32767;
            } else if (value < 65536) {
                lop = resolver.CHAR;
            } else {
                lop = resolver.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 = resolver.typeVariable((Local) rv);
            }
        } else if (rv instanceof DoubleConstant) {
        } else if (rv instanceof FloatConstant) {
        } else if (rv instanceof IntConstant) {
            int value = ((IntConstant) rv).value;
            if (value < -32768) {
                rop = resolver.INT;
            } else if (value < -128) {
                rop = resolver.SHORT;
            } else if (value < 0) {
                rop = resolver.BYTE;
            } else if (value < 2) {
                rop = resolver.R0_1;
            } else if (value < 128) {
                rop = resolver.R0_127;
            } else if (value < 32768) {
                rop = resolver.R0_32767;
            } else if (value < 65536) {
                rop = resolver.CHAR;
            } else {
                rop = resolver.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 DivExpr) || (be instanceof RemExpr) || (be instanceof MulExpr)) {
            if (lop != null && rop != null) {
                if (uses) {
                    if (lop.type() == null) {
                        lop.addParent(resolver.INT);
                    }
                    if (rop.type() == null) {
                        rop.addParent(resolver.INT);
                    }
                }
                right = resolver.INT;
            }
        } else if ((be instanceof AndExpr) || (be instanceof OrExpr) || (be instanceof XorExpr)) {
            if (lop != null && rop != null) {
                TypeVariable common = resolver.typeVariable();
                if (rop != null)
                    rop.addParent(common);
                if (lop != null)
                    lop.addParent(common);
                right = common;
            }
        } else if (be instanceof ShlExpr) {
            if (uses) {
                if (lop != null && lop.type() == null) {
                    lop.addParent(resolver.INT);
                }
                if (rop.type() == null) {
                    rop.addParent(resolver.INT);
                }
            }
            right = (lop == null) ? null : resolver.INT;
        } else if ((be instanceof ShrExpr) || (be instanceof UshrExpr)) {
            if (uses) {
                if (lop != null && lop.type() == null) {
                    lop.addParent(resolver.INT);
                }
                if (rop.type() == null) {
                    rop.addParent(resolver.INT);
                }
            }
            right = lop;
        } else if ((be instanceof CmpExpr) || (be instanceof CmpgExpr) || (be instanceof CmplExpr)) {
            right = resolver.BYTE;
        } else if ((be instanceof EqExpr) || (be instanceof GeExpr) || (be instanceof GtExpr) || (be instanceof LeExpr) || (be instanceof LtExpr) || (be instanceof NeExpr)) {
            if (uses) {
                TypeVariable common = resolver.typeVariable();
                if (rop != null)
                    rop.addParent(common);
                if (lop != null)
                    lop.addParent(common);
            }
            right = resolver.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 = resolver.typeVariable(ce.getCastType());
        }
    } else if (r instanceof InstanceOfExpr) {
        right = resolver.BOOLEAN;
    } else if (r instanceof InvokeExpr) {
        InvokeExpr ie = (InvokeExpr) r;
        handleInvokeExpr(ie);
        if (ie.getMethodRef().returnType() instanceof IntegerType) {
            right = resolver.typeVariable(ie.getMethodRef().returnType());
        }
    } else if (r instanceof NewArrayExpr) {
        NewArrayExpr nae = (NewArrayExpr) r;
        if (uses) {
            Value size = nae.getSize();
            if (size instanceof Local) {
                TypeVariable var = resolver.typeVariable((Local) size);
                var.addParent(resolver.INT);
            }
        }
    } else if (r instanceof NewExpr) {
    } else if (r instanceof NewMultiArrayExpr) {
        NewMultiArrayExpr nmae = (NewMultiArrayExpr) r;
        if (uses) {
            for (int i = 0; i < nmae.getSizeCount(); i++) {
                Value size = nmae.getSize(i);
                if (size instanceof Local) {
                    TypeVariable var = resolver.typeVariable((Local) size);
                    var.addParent(resolver.INT);
                }
            }
        }
    } else if (r instanceof LengthExpr) {
        right = resolver.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) {
                if (uses) {
                    resolver.typeVariable(local).addParent(resolver.INT);
                }
                TypeVariable v = resolver.typeVariable();
                v.addChild(resolver.BYTE);
                v.addChild(resolver.typeVariable(local));
                right = v;
            }
        } else if (ne.getOp() instanceof DoubleConstant) {
        } else if (ne.getOp() instanceof FloatConstant) {
        } else if (ne.getOp() instanceof IntConstant) {
            int value = ((IntConstant) ne.getOp()).value;
            if (value < -32768) {
                right = resolver.INT;
            } else if (value < -128) {
                right = resolver.SHORT;
            } else if (value < 0) {
                right = resolver.BYTE;
            } else if (value < 2) {
                right = resolver.BYTE;
            } else if (value < 128) {
                right = resolver.BYTE;
            } else if (value < 32768) {
                right = resolver.SHORT;
            } else if (value < 65536) {
                right = resolver.INT;
            } else {
                right = resolver.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 = resolver.typeVariable(local);
        }
    } else if (r instanceof InstanceFieldRef) {
        InstanceFieldRef ref = (InstanceFieldRef) r;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            right = resolver.typeVariable(ref.getFieldRef().type());
        }
    } else if (r instanceof StaticFieldRef) {
        StaticFieldRef ref = (StaticFieldRef) r;
        if (ref.getFieldRef().type() instanceof IntegerType) {
            right = resolver.typeVariable(ref.getFieldRef().type());
        }
    } else {
        throw new RuntimeException("Unhandled assignment right hand side type: " + r.getClass());
    }
    if (left != null && right != null && (left.type() == null || right.type() == null)) {
        right.addParent(left);
    }
}

Example 4 with NullConstant

use of soot.jimple.NullConstant in project soot by Sable.

the class DeadAssignmentEliminator method internalTransform.

/**
 * Eliminates dead code in a linear fashion.  Complexity is linear
 * with respect to the statements.
 *
 * Does not work on grimp code because of the check on the right hand
 * side for side effects.
 */
@Override
protected void internalTransform(Body b, String phaseName, Map<String, String> options) {
    boolean eliminateOnlyStackLocals = PhaseOptions.getBoolean(options, "only-stack-locals");
    final Options soptions = Options.v();
    if (soptions.verbose()) {
        logger.debug("[" + b.getMethod().getName() + "] Eliminating dead code...");
    }
    if (soptions.time()) {
        Timers.v().deadCodeTimer.start();
    }
    Chain<Unit> units = b.getUnits();
    Deque<Unit> q = new ArrayDeque<Unit>(units.size());
    // Make a first pass through the statements, noting
    // the statements we must absolutely keep.
    boolean isStatic = b.getMethod().isStatic();
    boolean allEssential = true;
    boolean checkInvoke = false;
    Local thisLocal = null;
    for (Iterator<Unit> it = units.iterator(); it.hasNext(); ) {
        Unit s = it.next();
        boolean isEssential = true;
        if (s instanceof NopStmt) {
            // Hack: do not remove nop if is is used for a Trap
            // which is at the very end of the code.
            boolean removeNop = it.hasNext();
            if (!removeNop) {
                removeNop = true;
                for (Trap t : b.getTraps()) {
                    if (t.getEndUnit() == s) {
                        removeNop = false;
                        break;
                    }
                }
            }
            if (removeNop) {
                it.remove();
                continue;
            }
        } else if (s instanceof AssignStmt) {
            AssignStmt as = (AssignStmt) s;
            Value lhs = as.getLeftOp();
            Value rhs = as.getRightOp();
            // Stmt is of the form a = a which is useless
            if (lhs == rhs && lhs instanceof Local) {
                it.remove();
                continue;
            }
            if (lhs instanceof Local && (!eliminateOnlyStackLocals || ((Local) lhs).getName().startsWith("$") || lhs.getType() instanceof NullType)) {
                isEssential = false;
                if (!checkInvoke) {
                    checkInvoke = as.containsInvokeExpr();
                }
                if (rhs instanceof CastExpr) {
                    // CastExpr          : can trigger ClassCastException, but null-casts never fail
                    CastExpr ce = (CastExpr) rhs;
                    Type t = ce.getCastType();
                    Value v = ce.getOp();
                    isEssential = !(v instanceof NullConstant && t instanceof RefType);
                } else if (rhs instanceof InvokeExpr || rhs instanceof ArrayRef || rhs instanceof NewExpr || rhs instanceof NewArrayExpr || rhs instanceof NewMultiArrayExpr) {
                    // ArrayRef          : can have side effects (like throwing a null pointer exception)
                    // InvokeExpr        : can have side effects (like throwing a null pointer exception)
                    // NewArrayExpr      : can throw exception
                    // NewMultiArrayExpr : can throw exception
                    // NewExpr           : can trigger class initialization
                    isEssential = true;
                } else if (rhs instanceof FieldRef) {
                    // Can trigger class initialization
                    isEssential = true;
                    if (rhs instanceof InstanceFieldRef) {
                        InstanceFieldRef ifr = (InstanceFieldRef) rhs;
                        if (!isStatic && thisLocal == null) {
                            thisLocal = b.getThisLocal();
                        }
                        // Any InstanceFieldRef may have side effects,
                        // unless the base is reading from 'this'
                        // in a non-static method
                        isEssential = (isStatic || thisLocal != ifr.getBase());
                    }
                } else if (rhs instanceof DivExpr || rhs instanceof RemExpr) {
                    BinopExpr expr = (BinopExpr) rhs;
                    Type t1 = expr.getOp1().getType();
                    Type t2 = expr.getOp2().getType();
                    // Can trigger a division by zero
                    boolean t2Int = t2 instanceof IntType;
                    isEssential = t2Int || t1 instanceof IntType || t1 instanceof LongType || t2 instanceof LongType || t1 instanceof UnknownType || t2 instanceof UnknownType;
                    if (isEssential && t2Int) {
                        Value v = expr.getOp2();
                        if (v instanceof IntConstant) {
                            IntConstant i = (IntConstant) v;
                            isEssential = (i.value == 0);
                        } else
                            // could be 0, we don't know
                            isEssential = true;
                    }
                    if (isEssential && t2 instanceof LongType) {
                        Value v = expr.getOp2();
                        if (v instanceof LongConstant) {
                            LongConstant l = (LongConstant) v;
                            isEssential = (l.value == 0);
                        } else
                            // could be 0, we don't know
                            isEssential = true;
                    }
                }
            }
        }
        if (isEssential) {
            q.addFirst(s);
        }
        allEssential &= isEssential;
    }
    if (checkInvoke || !allEssential) {
        // Add all the statements which are used to compute values
        // for the essential statements, recursively
        final LocalDefs localDefs = LocalDefs.Factory.newLocalDefs(b);
        if (!allEssential) {
            Set<Unit> essential = new HashSet<Unit>(b.getUnits().size());
            while (!q.isEmpty()) {
                Unit s = q.removeFirst();
                if (essential.add(s)) {
                    for (ValueBox box : s.getUseBoxes()) {
                        Value v = box.getValue();
                        if (v instanceof Local) {
                            Local l = (Local) v;
                            List<Unit> defs = localDefs.getDefsOfAt(l, s);
                            if (defs != null)
                                q.addAll(defs);
                        }
                    }
                }
            }
            // Remove the dead statements
            units.retainAll(essential);
        }
        if (checkInvoke) {
            final LocalUses localUses = LocalUses.Factory.newLocalUses(b, localDefs);
            // Eliminate dead assignments from invokes such as x = f(), where
            // x is no longer used
            List<AssignStmt> postProcess = new ArrayList<AssignStmt>();
            for (Unit u : units) {
                if (u instanceof AssignStmt) {
                    AssignStmt s = (AssignStmt) u;
                    if (s.containsInvokeExpr()) {
                        // Just find one use of l which is essential
                        boolean deadAssignment = true;
                        for (UnitValueBoxPair pair : localUses.getUsesOf(s)) {
                            if (units.contains(pair.unit)) {
                                deadAssignment = false;
                                break;
                            }
                        }
                        if (deadAssignment) {
                            postProcess.add(s);
                        }
                    }
                }
            }
            final Jimple jimple = Jimple.v();
            for (AssignStmt s : postProcess) {
                // Transform it into a simple invoke.
                Stmt newInvoke = jimple.newInvokeStmt(s.getInvokeExpr());
                newInvoke.addAllTagsOf(s);
                units.swapWith(s, newInvoke);
                // If we have a callgraph, we need to fix it
                if (Scene.v().hasCallGraph())
                    Scene.v().getCallGraph().swapEdgesOutOf(s, newInvoke);
            }
        }
    }
    if (soptions.time()) {
        Timers.v().deadCodeTimer.end();
    }
}

Example 5 with NullConstant

use of soot.jimple.NullConstant in project soot by Sable.

the class NullCheckEliminator method internalTransform.

public void internalTransform(Body body, String phaseName, Map<String, String> options) {
    // really, the analysis should be able to use its own results to determine
    // that some branches are dead, but since it doesn't we just iterate.
    boolean changed;
    do {
        changed = false;
        NullnessAnalysis analysis = analysisFactory.newAnalysis(new ExceptionalUnitGraph(body));
        Chain<Unit> units = body.getUnits();
        Stmt s;
        for (s = (Stmt) units.getFirst(); s != null; s = (Stmt) units.getSuccOf(s)) {
            if (!(s instanceof IfStmt))
                continue;
            IfStmt is = (IfStmt) s;
            Value c = is.getCondition();
            if (!(c instanceof EqExpr || c instanceof NeExpr))
                continue;
            BinopExpr e = (BinopExpr) c;
            Immediate i = null;
            if (e.getOp1() instanceof NullConstant)
                i = (Immediate) e.getOp2();
            if (e.getOp2() instanceof NullConstant)
                i = (Immediate) e.getOp1();
            if (i == null)
                continue;
            boolean alwaysNull = analysis.isAlwaysNullBefore(s, i);
            boolean alwaysNonNull = analysis.isAlwaysNonNullBefore(s, i);
            // -1 => condition is false, 1 => condition is true
            int elim = 0;
            if (alwaysNonNull)
                elim = c instanceof EqExpr ? -1 : 1;
            if (alwaysNull)
                elim = c instanceof EqExpr ? 1 : -1;
            Stmt newstmt = null;
            if (elim == -1)
                newstmt = Jimple.v().newNopStmt();
            if (elim == 1)
                newstmt = Jimple.v().newGotoStmt(is.getTarget());
            if (newstmt != null) {
                units.swapWith(s, newstmt);
                s = newstmt;
                changed = true;
            }
        }
    } while (changed);
}