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 kFmt45cc, // op {vC, vD, vE, vF, vG}, meth@BBBB, proto@HHHH
65 kFmt4rcc, // op {VCCCC .. v(CCCC+AA-1)}, meth@BBBB, proto@HHHH
66 };
67
68 /*
69 * Types of indexed reference that are associated with opcodes whose
70 * formats include such an indexed reference (e.g., 21c and 35c).
71 */
72 enum InstructionIndexType {
73 kIndexUnknown = 0,
74 kIndexNone, // has no index
75 kIndexVaries, // "It depends." Used for throw-verification-error
76 kIndexTypeRef, // type reference index
77 kIndexStringRef, // string reference index
78 kIndexMethodRef, // method reference index
79 kIndexFieldRef, // field reference index
80 kIndexInlineMethod, // inline method index (for inline linked methods)
81 kIndexVtableOffset, // vtable offset (for static linked methods)
82 kIndexFieldOffset, // field offset (for static linked fields)
83 kIndexMethodAndProtoRef, // method index and proto index
84 kCallSiteRef // call site index
85 };
86
87 /*
88 * Instruction width implied by an opcode's format; a value in the
89 * range 0 to 5. Note that there are special "pseudo-instructions"
90 * which are used to encode switch and data tables, and these don't
91 * have a fixed width. See dexGetWidthFromInstruction(), below.
92 */
93 typedef u1 InstructionWidth;
94
95 /*
96 * Opcode control flow flags, used by the verifier and JIT.
97 */
98 typedef u1 OpcodeFlags;
99 enum OpcodeFlagsBits {
100 kInstrCanBranch = 1, // conditional or unconditional branch
101 kInstrCanContinue = 1 << 1, // flow can continue to next statement
102 kInstrCanSwitch = 1 << 2, // switch statement
103 kInstrCanThrow = 1 << 3, // could cause an exception to be thrown
104 kInstrCanReturn = 1 << 4, // returns, no additional statements
105 kInstrInvoke = 1 << 5, // a flavor of invoke
106 };
107
108 /*
109 * Struct that includes a pointer to each of the opcode information
110 * tables.
111 *
112 * Note: We use "u1*" here instead of the names of the enumerated
113 * types to guarantee that elements don't use much space. We hold out
114 * hope for a standard way to indicate the size of an enumerated type
115 * that works for both C and C++, but in the mean time, this will
116 * suffice.
117 */
118 struct InstructionInfoTables {
119 u1* formats; /* InstructionFormat elements */
120 u1* indexTypes; /* InstructionIndexType elements */
121 OpcodeFlags* flags;
122 InstructionWidth* widths;
123 };
124
125 /*
126 * Global InstructionInfoTables struct.
127 */
128 extern InstructionInfoTables gDexOpcodeInfo;
129
130 /*
131 * Holds the contents of a decoded instruction.
132 */
133 struct DecodedInstruction {
134 u4 vA;
135 u4 vB;
136 u8 vB_wide; /* for kFmt51l */
137 u4 vC;
138 u4 arg[5]; /* vC/D/E/F/G in invoke or filled-new-array */
139 Opcode opcode;
140 InstructionIndexType indexType;
141 };
142
143 /*
144 * Return the instruction width of the specified opcode, or 0 if not defined.
145 */
dexGetWidthFromOpcode(Opcode opcode)146 DEX_INLINE size_t dexGetWidthFromOpcode(Opcode opcode)
147 {
148 assert((u4) opcode < kNumPackedOpcodes);
149 return gDexOpcodeInfo.widths[opcode];
150 }
151
152 /*
153 * Return the width of the specified instruction, or 0 if not defined. Also
154 * works for special OP_NOP entries, including switch statement data tables
155 * and array data.
156 */
157 size_t dexGetWidthFromInstruction(const u2* insns);
158
159 /*
160 * Returns the flags for the specified opcode.
161 */
dexGetFlagsFromOpcode(Opcode opcode)162 DEX_INLINE OpcodeFlags dexGetFlagsFromOpcode(Opcode opcode)
163 {
164 assert((u4) opcode < kNumPackedOpcodes);
165 return gDexOpcodeInfo.flags[opcode];
166 }
167
168 /*
169 * Returns true if the given flags represent a goto (unconditional branch).
170 */
dexIsGoto(OpcodeFlags flags)171 DEX_INLINE bool dexIsGoto(OpcodeFlags flags)
172 {
173 return (flags & (kInstrCanBranch | kInstrCanContinue)) == kInstrCanBranch;
174 }
175
176 /*
177 * Return the instruction format for the specified opcode.
178 */
dexGetFormatFromOpcode(Opcode opcode)179 DEX_INLINE InstructionFormat dexGetFormatFromOpcode(Opcode opcode)
180 {
181 assert((u4) opcode < kNumPackedOpcodes);
182 return (InstructionFormat) gDexOpcodeInfo.formats[opcode];
183 }
184
185 /*
186 * Return the instruction index type for the specified opcode.
187 */
dexGetIndexTypeFromOpcode(Opcode opcode)188 DEX_INLINE InstructionIndexType dexGetIndexTypeFromOpcode(Opcode opcode)
189 {
190 assert((u4) opcode < kNumPackedOpcodes);
191 return (InstructionIndexType) gDexOpcodeInfo.indexTypes[opcode];
192 }
193
194 /*
195 * Decode the instruction pointed to by "insns".
196 */
197 void dexDecodeInstruction(const u2* insns, DecodedInstruction* pDec);
198
199 #endif // LIBDEX_INSTRUTILS_H_
200