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c906108c 1/* Definitions for expressions designed to be executed on the agent
6aba47ca 2 Copyright (C) 1998, 1999, 2000, 2007 Free Software Foundation, Inc.
c906108c 3
c5aa993b 4 This file is part of GDB.
c906108c 5
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6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
c906108c 10
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11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
c906108c 15
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16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
197e01b6
EZ
18 Foundation, Inc., 51 Franklin Street, Fifth Floor,
19 Boston, MA 02110-1301, USA. */
c906108c 20
c906108c
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21#ifndef AGENTEXPR_H
22#define AGENTEXPR_H
23
d16aafd8
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24#include "doublest.h" /* For DOUBLEST. */
25
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26/* It's sometimes useful to be able to debug programs that you can't
27 really stop for more than a fraction of a second. To this end, the
28 user can specify a tracepoint (like a breakpoint, but you don't
29 stop at it), and specify a bunch of expressions to record the
30 values of when that tracepoint is reached. As the program runs,
31 GDB collects the values. At any point (possibly while values are
32 still being collected), the user can display the collected values.
33
34 This is used with remote debugging; we don't really support it on
35 native configurations.
36
37 This means that expressions are being evaluated by the remote agent,
38 which doesn't have any access to the symbol table information, and
39 needs to be small and simple.
40
41 The agent_expr routines and datatypes are a bytecode language
42 designed to be executed by the agent. Agent expressions work in
43 terms of fixed-width values, operators, memory references, and
44 register references. You can evaluate a agent expression just given
45 a bunch of memory and register values to sniff at; you don't need
46 any symbolic information like variable names, types, etc.
47
48 GDB translates source expressions, whose meaning depends on
49 symbolic information, into agent bytecode expressions, whose meaning
50 is independent of symbolic information. This means the agent can
51 evaluate them on the fly without reference to data only available
52 to the host GDB. */
c906108c 53\f
c5aa993b 54
c906108c
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55/* Agent expression data structures. */
56
57/* The type of an element of the agent expression stack.
58 The bytecode operation indicates which element we should access;
59 the value itself has no typing information. GDB generates all
60 bytecode streams, so we don't have to worry about type errors. */
61
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62union agent_val
63 {
64 LONGEST l;
65 DOUBLEST d;
66 };
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67
68/* A buffer containing a agent expression. */
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69struct agent_expr
70 {
71 unsigned char *buf;
72 int len; /* number of characters used */
73 int size; /* allocated size */
74 CORE_ADDR scope;
75 };
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76
77
78
79
80/* The actual values of the various bytecode operations.
81
82 Other independent implementations of the agent bytecode engine will
83 rely on the exact values of these enums, and may not be recompiled
84 when we change this table. The numeric values should remain fixed
85 whenever possible. Thus, we assign them values explicitly here (to
86 allow gaps to form safely), and the disassembly table in
87 agentexpr.h behaves like an opcode map. If you want to see them
88 grouped logically, see doc/agentexpr.texi. */
89
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90enum agent_op
91 {
92 aop_float = 0x01,
93 aop_add = 0x02,
94 aop_sub = 0x03,
95 aop_mul = 0x04,
96 aop_div_signed = 0x05,
97 aop_div_unsigned = 0x06,
98 aop_rem_signed = 0x07,
99 aop_rem_unsigned = 0x08,
100 aop_lsh = 0x09,
101 aop_rsh_signed = 0x0a,
102 aop_rsh_unsigned = 0x0b,
103 aop_trace = 0x0c,
104 aop_trace_quick = 0x0d,
105 aop_log_not = 0x0e,
106 aop_bit_and = 0x0f,
107 aop_bit_or = 0x10,
108 aop_bit_xor = 0x11,
109 aop_bit_not = 0x12,
110 aop_equal = 0x13,
111 aop_less_signed = 0x14,
112 aop_less_unsigned = 0x15,
113 aop_ext = 0x16,
114 aop_ref8 = 0x17,
115 aop_ref16 = 0x18,
116 aop_ref32 = 0x19,
117 aop_ref64 = 0x1a,
118 aop_ref_float = 0x1b,
119 aop_ref_double = 0x1c,
120 aop_ref_long_double = 0x1d,
121 aop_l_to_d = 0x1e,
122 aop_d_to_l = 0x1f,
123 aop_if_goto = 0x20,
124 aop_goto = 0x21,
125 aop_const8 = 0x22,
126 aop_const16 = 0x23,
127 aop_const32 = 0x24,
128 aop_const64 = 0x25,
129 aop_reg = 0x26,
130 aop_end = 0x27,
131 aop_dup = 0x28,
132 aop_pop = 0x29,
133 aop_zero_ext = 0x2a,
134 aop_swap = 0x2b,
135 aop_trace16 = 0x30,
136 aop_last
137 };
138\f
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139
140
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141/* Functions for building expressions. */
142
143/* Allocate a new, empty agent expression. */
a14ed312 144extern struct agent_expr *new_agent_expr (CORE_ADDR);
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145
146/* Free a agent expression. */
a14ed312 147extern void free_agent_expr (struct agent_expr *);
f23d52e0 148extern struct cleanup *make_cleanup_free_agent_expr (struct agent_expr *);
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149
150/* Append a simple operator OP to EXPR. */
a14ed312 151extern void ax_simple (struct agent_expr *EXPR, enum agent_op OP);
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152
153/* Append the floating-point prefix, for the next bytecode. */
154#define ax_float(EXPR) (ax_simple ((EXPR), aop_float))
155
156/* Append a sign-extension instruction to EXPR, to extend an N-bit value. */
a14ed312 157extern void ax_ext (struct agent_expr *EXPR, int N);
c906108c
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158
159/* Append a zero-extension instruction to EXPR, to extend an N-bit value. */
a14ed312 160extern void ax_zero_ext (struct agent_expr *EXPR, int N);
c906108c
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161
162/* Append a trace_quick instruction to EXPR, to record N bytes. */
a14ed312 163extern void ax_trace_quick (struct agent_expr *EXPR, int N);
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164
165/* Append a goto op to EXPR. OP is the actual op (must be aop_goto or
166 aop_if_goto). We assume we don't know the target offset yet,
167 because it's probably a forward branch, so we leave space in EXPR
168 for the target, and return the offset in EXPR of that space, so we
169 can backpatch it once we do know the target offset. Use ax_label
170 to do the backpatching. */
a14ed312 171extern int ax_goto (struct agent_expr *EXPR, enum agent_op OP);
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172
173/* Suppose a given call to ax_goto returns some value PATCH. When you
174 know the offset TARGET that goto should jump to, call
c5aa993b 175 ax_label (EXPR, PATCH, TARGET)
c906108c 176 to patch TARGET into the ax_goto instruction. */
a14ed312 177extern void ax_label (struct agent_expr *EXPR, int patch, int target);
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178
179/* Assemble code to push a constant on the stack. */
a14ed312
KB
180extern void ax_const_l (struct agent_expr *EXPR, LONGEST l);
181extern void ax_const_d (struct agent_expr *EXPR, LONGEST d);
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182
183/* Assemble code to push the value of register number REG on the
184 stack. */
a14ed312 185extern void ax_reg (struct agent_expr *EXPR, int REG);
c906108c 186\f
c5aa993b 187
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188/* Functions for printing out expressions, and otherwise debugging
189 things. */
190
191/* Disassemble the expression EXPR, writing to F. */
d9fcf2fb 192extern void ax_print (struct ui_file *f, struct agent_expr * EXPR);
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193
194/* An entry in the opcode map. */
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195struct aop_map
196 {
c906108c 197
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198 /* The name of the opcode. Null means that this entry is not a
199 valid opcode --- a hole in the opcode space. */
200 char *name;
c906108c 201
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202 /* All opcodes take no operands from the bytecode stream, or take
203 unsigned integers of various sizes. If this is a positive number
204 n, then the opcode is followed by an n-byte operand, which should
205 be printed as an unsigned integer. If this is zero, then the
206 opcode takes no operands from the bytecode stream.
c906108c 207
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208 If we get more complicated opcodes in the future, don't add other
209 magic values of this; that's a crock. Add an `enum encoding'
210 field to this, or something like that. */
211 int op_size;
c906108c 212
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213 /* The size of the data operated upon, in bits, for bytecodes that
214 care about that (ref and const). Zero for all others. */
215 int data_size;
c906108c 216
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217 /* Number of stack elements consumed, and number produced. */
218 int consumed, produced;
219 };
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220
221/* Map of the bytecodes, indexed by bytecode number. */
222extern struct aop_map aop_map[];
223
224/* Different kinds of flaws an agent expression might have, as
225 detected by agent_reqs. */
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226enum agent_flaws
227 {
228 agent_flaw_none = 0, /* code is good */
c906108c 229
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230 /* There is an invalid instruction in the stream. */
231 agent_flaw_bad_instruction,
c906108c 232
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233 /* There is an incomplete instruction at the end of the expression. */
234 agent_flaw_incomplete_instruction,
c906108c 235
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236 /* agent_reqs was unable to prove that every jump target is to a
237 valid offset. Valid offsets are within the bounds of the
238 expression, and to a valid instruction boundary. */
239 agent_flaw_bad_jump,
c906108c 240
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241 /* agent_reqs was unable to prove to its satisfaction that, for each
242 jump target location, the stack will have the same height whether
243 that location is reached via a jump or by straight execution. */
244 agent_flaw_height_mismatch,
c906108c 245
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246 /* agent_reqs was unable to prove that every instruction following
247 an unconditional jump was the target of some other jump. */
248 agent_flaw_hole
249 };
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250
251/* Structure describing the requirements of a bytecode expression. */
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252struct agent_reqs
253 {
254
255 /* If the following is not equal to agent_flaw_none, the rest of the
256 information in this structure is suspect. */
257 enum agent_flaws flaw;
c906108c 258
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259 /* Number of elements left on stack at end; may be negative if expr
260 only consumes elements. */
261 int final_height;
c906108c 262
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263 /* Maximum and minimum stack height, relative to initial height. */
264 int max_height, min_height;
c906108c 265
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266 /* Largest `ref' or `const' opcode used, in bits. Zero means the
267 expression has no such instructions. */
268 int max_data_size;
c906108c 269
c5aa993b 270 /* Bit vector of registers used. Register R is used iff
c906108c 271
c5aa993b 272 reg_mask[R / 8] & (1 << (R % 8))
c906108c 273
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274 is non-zero. Note! You may not assume that this bitmask is long
275 enough to hold bits for all the registers of the machine; the
276 agent expression code has no idea how many registers the machine
277 has. However, the bitmask is reg_mask_len bytes long, so the
278 valid register numbers run from 0 to reg_mask_len * 8 - 1.
c906108c 279
c5aa993b 280 We're assuming eight-bit bytes. So sue me.
c906108c 281
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282 The caller should free reg_list when done. */
283 int reg_mask_len;
284 unsigned char *reg_mask;
285 };
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286
287
288/* Given an agent expression AX, fill in an agent_reqs structure REQS
289 describing it. */
a14ed312 290extern void ax_reqs (struct agent_expr *ax, struct agent_reqs *reqs);
c906108c
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291
292#endif /* AGENTEXPR_H */