1579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson/* 2579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Copyright (C) 2007 The Android Open Source Project 3579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * 4579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Licensed under the Apache License, Version 2.0 (the "License"); 5579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * you may not use this file except in compliance with the License. 6579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * You may obtain a copy of the License at 7579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * 8579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * http://www.apache.org/licenses/LICENSE-2.0 9579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * 10579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Unless required by applicable law or agreed to in writing, software 11579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * distributed under the License is distributed on an "AS IS" BASIS, 12579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * See the License for the specific language governing permissions and 14579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * limitations under the License. 15579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 16579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson 17579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilsonpackage com.android.dx.cf.code; 18579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson 19579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilsonimport com.android.dx.rop.type.Type; 20579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilsonimport com.android.dx.rop.type.TypeBearer; 21579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson 22579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson/** 23579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Utility methods to merge various frame information. 24579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 25579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilsonpublic final class Merger { 26579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /** 27579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Merges two frame types. 28579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * 29579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * @param ft1 {@code non-null;} a frame type 30579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * @param ft2 {@code non-null;} another frame type 31579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * @return {@code non-null;} the result of merging the two types 32579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 33579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson public static TypeBearer mergeType(TypeBearer ft1, TypeBearer ft2) { 34579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson if ((ft1 == null) || ft1.equals(ft2)) { 35579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return ft1; 36579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else if (ft2 == null) { 37579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return null; 38579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else { 39579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson Type type1 = ft1.getType(); 40579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson Type type2 = ft2.getType(); 41579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson 42579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson if (type1 == type2) { 43579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return type1; 44579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else if (type1.isReference() && type2.isReference()) { 45579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson if (type1 == Type.KNOWN_NULL) { 46579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /* 47579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * A known-null merges with any other reference type to 48579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * be that reference type. 49579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 50579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return type2; 51579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else if (type2 == Type.KNOWN_NULL) { 52579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /* 53579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * The same as above, but this time it's type2 that's 54579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * the known-null. 55579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 56579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return type1; 57579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else if (type1.isArray() && type2.isArray()) { 58579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson TypeBearer componentUnion = 59579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson mergeType(type1.getComponentType(), 60579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson type2.getComponentType()); 61579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson if (componentUnion == null) { 62579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /* 63579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * At least one of the types is a primitive type, 64579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * so the merged result is just Object. 65579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 66579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return Type.OBJECT; 67579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } 68579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return ((Type) componentUnion).getArrayType(); 69579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else { 70579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /* 71579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * All other unequal reference types get merged to be 72579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Object in this phase. This is fine here, but it 73579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * won't be the right thing to do in the verifier. 74579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 75579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return Type.OBJECT; 76579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } 77579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else if (type1.isIntlike() && type2.isIntlike()) { 78579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson /* 79579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * Merging two non-identical int-like types results in 80579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson * the type int. 81579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson */ 82579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return Type.INT; 83579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } else { 84579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson return null; 85579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } 86579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } 87579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson } 88579d7739c53a2707ad711a2d2cae46d7d782f06Jesse Wilson} 89