1 /*
2 * Copyright (C) 2008 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 /*
18 * Dalvik instruction utility functions.
19 */
20 #ifndef LIBDEX_INSTRUTILS_H_
21 #define LIBDEX_INSTRUTILS_H_
22
23 #include "DexFile.h"
24 #include "DexOpcodes.h"
25
26 /*
27 * Possible instruction formats associated with Dalvik opcodes.
28 *
29 * See the file opcode-gen/README.txt for information about updating
30 * opcodes and instruction formats.
31 */
32 enum InstructionFormat {
33 kFmt00x = 0, // unknown format (also used for "breakpoint" opcode)
34 kFmt10x, // op
35 kFmt12x, // op vA, vB
36 kFmt11n, // op vA, #+B
37 kFmt11x, // op vAA
38 kFmt10t, // op +AA
39 kFmt20bc, // [opt] op AA, thing@BBBB
40 kFmt20t, // op +AAAA
41 kFmt22x, // op vAA, vBBBB
42 kFmt21t, // op vAA, +BBBB
43 kFmt21s, // op vAA, #+BBBB
44 kFmt21h, // op vAA, #+BBBB00000[00000000]
45 kFmt21c, // op vAA, thing@BBBB
46 kFmt23x, // op vAA, vBB, vCC
47 kFmt22b, // op vAA, vBB, #+CC
48 kFmt22t, // op vA, vB, +CCCC
49 kFmt22s, // op vA, vB, #+CCCC
50 kFmt22c, // op vA, vB, thing@CCCC
51 kFmt22cs, // [opt] op vA, vB, field offset CCCC
52 kFmt30t, // op +AAAAAAAA
53 kFmt32x, // op vAAAA, vBBBB
54 kFmt31i, // op vAA, #+BBBBBBBB
55 kFmt31t, // op vAA, +BBBBBBBB
56 kFmt31c, // op vAA, string@BBBBBBBB
57 kFmt35c, // op {vC,vD,vE,vF,vG}, thing@BBBB
58 kFmt35ms, // [opt] invoke-virtual+super
59 kFmt3rc, // op {vCCCC .. v(CCCC+AA-1)}, thing@BBBB
60 kFmt3rms, // [opt] invoke-virtual+super/range
61 kFmt51l, // op vAA, #+BBBBBBBBBBBBBBBB
62 kFmt35mi, // [opt] inline invoke
63 kFmt3rmi, // [opt] inline invoke/range
64 };
65
66 /*
67 * Types of indexed reference that are associated with opcodes whose
68 * formats include such an indexed reference (e.g., 21c and 35c).
69 */
70 enum InstructionIndexType {
71 kIndexUnknown = 0,
72 kIndexNone, // has no index
73 kIndexVaries, // "It depends." Used for throw-verification-error
74 kIndexTypeRef, // type reference index
75 kIndexStringRef, // string reference index
76 kIndexMethodRef, // method reference index
77 kIndexFieldRef, // field reference index
78 kIndexInlineMethod, // inline method index (for inline linked methods)
79 kIndexVtableOffset, // vtable offset (for static linked methods)
80 kIndexFieldOffset // field offset (for static linked fields)
81 };
82
83 /*
84 * Instruction width implied by an opcode's format; a value in the
85 * range 0 to 5. Note that there are special "pseudo-instructions"
86 * which are used to encode switch and data tables, and these don't
87 * have a fixed width. See dexGetWidthFromInstruction(), below.
88 */
89 typedef u1 InstructionWidth;
90
91 /*
92 * Opcode control flow flags, used by the verifier and JIT.
93 */
94 typedef u1 OpcodeFlags;
95 enum OpcodeFlagsBits {
96 kInstrCanBranch = 1, // conditional or unconditional branch
97 kInstrCanContinue = 1 << 1, // flow can continue to next statement
98 kInstrCanSwitch = 1 << 2, // switch statement
99 kInstrCanThrow = 1 << 3, // could cause an exception to be thrown
100 kInstrCanReturn = 1 << 4, // returns, no additional statements
101 kInstrInvoke = 1 << 5, // a flavor of invoke
102 };
103
104 /*
105 * Struct that includes a pointer to each of the opcode information
106 * tables.
107 *
108 * Note: We use "u1*" here instead of the names of the enumerated
109 * types to guarantee that elements don't use much space. We hold out
110 * hope for a standard way to indicate the size of an enumerated type
111 * that works for both C and C++, but in the mean time, this will
112 * suffice.
113 */
114 struct InstructionInfoTables {
115 u1* formats; /* InstructionFormat elements */
116 u1* indexTypes; /* InstructionIndexType elements */
117 OpcodeFlags* flags;
118 InstructionWidth* widths;
119 };
120
121 /*
122 * Global InstructionInfoTables struct.
123 */
124 extern InstructionInfoTables gDexOpcodeInfo;
125
126 /*
127 * Holds the contents of a decoded instruction.
128 */
129 struct DecodedInstruction {
130 u4 vA;
131 u4 vB;
132 u8 vB_wide; /* for kFmt51l */
133 u4 vC;
134 u4 arg[5]; /* vC/D/E/F/G in invoke or filled-new-array */
135 Opcode opcode;
136 InstructionIndexType indexType;
137 };
138
139 /*
140 * Return the instruction width of the specified opcode, or 0 if not defined.
141 */
dexGetWidthFromOpcode(Opcode opcode)142 DEX_INLINE size_t dexGetWidthFromOpcode(Opcode opcode)
143 {
144 assert((u4) opcode < kNumPackedOpcodes);
145 return gDexOpcodeInfo.widths[opcode];
146 }
147
148 /*
149 * Return the width of the specified instruction, or 0 if not defined. Also
150 * works for special OP_NOP entries, including switch statement data tables
151 * and array data.
152 */
153 size_t dexGetWidthFromInstruction(const u2* insns);
154
155 /*
156 * Returns the flags for the specified opcode.
157 */
dexGetFlagsFromOpcode(Opcode opcode)158 DEX_INLINE OpcodeFlags dexGetFlagsFromOpcode(Opcode opcode)
159 {
160 assert((u4) opcode < kNumPackedOpcodes);
161 return gDexOpcodeInfo.flags[opcode];
162 }
163
164 /*
165 * Returns true if the given flags represent a goto (unconditional branch).
166 */
dexIsGoto(OpcodeFlags flags)167 DEX_INLINE bool dexIsGoto(OpcodeFlags flags)
168 {
169 return (flags & (kInstrCanBranch | kInstrCanContinue)) == kInstrCanBranch;
170 }
171
172 /*
173 * Return the instruction format for the specified opcode.
174 */
dexGetFormatFromOpcode(Opcode opcode)175 DEX_INLINE InstructionFormat dexGetFormatFromOpcode(Opcode opcode)
176 {
177 assert((u4) opcode < kNumPackedOpcodes);
178 return (InstructionFormat) gDexOpcodeInfo.formats[opcode];
179 }
180
181 /*
182 * Return the instruction index type for the specified opcode.
183 */
dexGetIndexTypeFromOpcode(Opcode opcode)184 DEX_INLINE InstructionIndexType dexGetIndexTypeFromOpcode(Opcode opcode)
185 {
186 assert((u4) opcode < kNumPackedOpcodes);
187 return (InstructionIndexType) gDexOpcodeInfo.indexTypes[opcode];
188 }
189
190 /*
191 * Decode the instruction pointed to by "insns".
192 */
193 void dexDecodeInstruction(const u2* insns, DecodedInstruction* pDec);
194
195 #endif // LIBDEX_INSTRUTILS_H_
196