| /* |
| * Copyright (C) 2008 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| /* |
| * Target-specific optimization and run-time hints |
| */ |
| |
| |
| #include "Dalvik.h" |
| #include "libdex/DexClass.h" |
| |
| #include <stdlib.h> |
| #include <stddef.h> |
| #include <sys/stat.h> |
| |
| |
| /* |
| * The class loader will associate with each method a 32-bit info word |
| * (jniArgInfo) to support JNI calls. The high order 4 bits of this word |
| * are the same for all targets, while the lower 28 are used for hints to |
| * allow accelerated JNI bridge transfers. |
| * |
| * jniArgInfo (32-bit int) layout: |
| * |
| * SRRRHHHH HHHHHHHH HHHHHHHH HHHHHHHH |
| * |
| * S - if set, ignore the hints and do things the hard way (scan signature) |
| * R - return-type enumeration |
| * H - target-specific hints (see below for details) |
| * |
| * This function produces arm-specific hints - specifically a description |
| * of padding required to keep all 64-bit parameters properly aligned. |
| * |
| * ARM JNI hint format |
| * |
| * LLLL FFFFFFFF FFFFFFFF FFFFFFFF |
| * |
| * L - number of double-words of storage required on the stack (0-30 words) |
| * F - pad flag -- if set, write a pad word to the stack before copying |
| * the next 32 bits |
| * |
| * If there are too many arguments to construct valid hints, this function will |
| * return a result with the S bit set. |
| */ |
| u4 dvmPlatformInvokeHints(const DexProto* proto) |
| { |
| const char* sig = dexProtoGetShorty(proto); |
| int padFlags, jniHints; |
| char sigByte; |
| int stackOffset, padMask, hints; |
| |
| stackOffset = padFlags = 0; |
| padMask = 0x00000001; |
| |
| /* Skip past the return type */ |
| sig++; |
| |
| while (true) { |
| sigByte = *(sig++); |
| |
| if (sigByte == '\0') |
| break; |
| |
| if (sigByte == 'D' || sigByte == 'J') { |
| if ((stackOffset & 1) != 0) { |
| padFlags |= padMask; |
| stackOffset++; |
| padMask <<= 1; |
| } |
| stackOffset += 2; |
| padMask <<= 2; |
| } else { |
| stackOffset++; |
| padMask <<= 1; |
| } |
| } |
| |
| jniHints = 0; |
| |
| if (stackOffset > DALVIK_JNI_COUNT_SHIFT) { |
| /* too big for "fast" version */ |
| jniHints = DALVIK_JNI_NO_ARG_INFO; |
| } else { |
| assert((padFlags & (0xffffffff << DALVIK_JNI_COUNT_SHIFT)) == 0); |
| stackOffset -= 2; // r2/r3 holds first two items |
| if (stackOffset < 0) |
| stackOffset = 0; |
| jniHints |= ((stackOffset+1) / 2) << DALVIK_JNI_COUNT_SHIFT; |
| jniHints |= padFlags; |
| } |
| |
| return jniHints; |
| } |