1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.dx.rop.code; 18 19 /** 20 * Interface for "advice" passed from the late stage of translation back 21 * to the early stage. This allows for the final target architecture to 22 * exert its influence early in the translation process without having 23 * the early stage code be explicitly tied to the target. 24 */ 25 public interface TranslationAdvice { 26 /** 27 * Returns an indication of whether the target can directly represent an 28 * instruction with the given opcode operating on the given arguments, 29 * where the last source argument is used as a constant. (That is, the 30 * last argument must have a type which indicates it is a known constant.) 31 * The instruction associated must have exactly two sources. 32 * 33 * @param opcode {@code non-null;} the opcode 34 * @param sourceA {@code non-null;} the first source 35 * @param sourceB {@code non-null;} the second source 36 * @return {@code true} iff the target can represent the operation 37 * using a constant for the last argument 38 */ 39 public boolean hasConstantOperation(Rop opcode, 40 RegisterSpec sourceA, RegisterSpec sourceB); 41 42 /** 43 * Returns true if the translation target requires the sources of the 44 * specified opcode to be in order and contiguous (eg, for an invoke-range) 45 * 46 * @param opcode {@code non-null;} opcode 47 * @param sources {@code non-null;} source list 48 * @return {@code true} iff the target requires the sources to be 49 * in order and contiguous. 50 */ 51 public boolean requiresSourcesInOrder(Rop opcode, RegisterSpecList sources); 52 53 /** 54 * Gets the maximum register width that can be represented optimally. 55 * For example, Dex bytecode does not have instruction forms that take 56 * register numbers larger than 15 for all instructions so 57 * DexTranslationAdvice returns 15 here. 58 * 59 * @return register count noted above 60 */ 61 public int getMaxOptimalRegisterCount(); 62 } 63
