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c906108c | 1 | /* Definitions for expressions designed to be executed on the agent |
0b302171 | 2 | Copyright (C) 1998-2000, 2007-2012 Free Software Foundation, Inc. |
c906108c | 3 | |
c5aa993b | 4 | This file is part of GDB. |
c906108c | 5 | |
c5aa993b JM |
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 | |
a9762ec7 | 8 | the Free Software Foundation; either version 3 of the License, or |
c5aa993b | 9 | (at your option) any later version. |
c906108c | 10 | |
c5aa993b JM |
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 | |
c5aa993b | 16 | You should have received a copy of the GNU General Public License |
a9762ec7 | 17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
c906108c | 18 | |
c906108c SS |
19 | #ifndef AGENTEXPR_H |
20 | #define AGENTEXPR_H | |
21 | ||
d16aafd8 AC |
22 | #include "doublest.h" /* For DOUBLEST. */ |
23 | ||
c906108c SS |
24 | /* It's sometimes useful to be able to debug programs that you can't |
25 | really stop for more than a fraction of a second. To this end, the | |
26 | user can specify a tracepoint (like a breakpoint, but you don't | |
27 | stop at it), and specify a bunch of expressions to record the | |
28 | values of when that tracepoint is reached. As the program runs, | |
29 | GDB collects the values. At any point (possibly while values are | |
30 | still being collected), the user can display the collected values. | |
31 | ||
32 | This is used with remote debugging; we don't really support it on | |
33 | native configurations. | |
34 | ||
35 | This means that expressions are being evaluated by the remote agent, | |
36 | which doesn't have any access to the symbol table information, and | |
37 | needs to be small and simple. | |
38 | ||
39 | The agent_expr routines and datatypes are a bytecode language | |
40 | designed to be executed by the agent. Agent expressions work in | |
41 | terms of fixed-width values, operators, memory references, and | |
42 | register references. You can evaluate a agent expression just given | |
43 | a bunch of memory and register values to sniff at; you don't need | |
44 | any symbolic information like variable names, types, etc. | |
45 | ||
46 | GDB translates source expressions, whose meaning depends on | |
47 | symbolic information, into agent bytecode expressions, whose meaning | |
48 | is independent of symbolic information. This means the agent can | |
49 | evaluate them on the fly without reference to data only available | |
50 | to the host GDB. */ | |
c906108c | 51 | \f |
c5aa993b | 52 | |
35c9c7ba SS |
53 | /* Different kinds of flaws an agent expression might have, as |
54 | detected by ax_reqs. */ | |
55 | enum agent_flaws | |
56 | { | |
57 | agent_flaw_none = 0, /* code is good */ | |
58 | ||
59 | /* There is an invalid instruction in the stream. */ | |
60 | agent_flaw_bad_instruction, | |
61 | ||
62 | /* There is an incomplete instruction at the end of the expression. */ | |
63 | agent_flaw_incomplete_instruction, | |
64 | ||
65 | /* ax_reqs was unable to prove that every jump target is to a | |
66 | valid offset. Valid offsets are within the bounds of the | |
67 | expression, and to a valid instruction boundary. */ | |
68 | agent_flaw_bad_jump, | |
69 | ||
70 | /* ax_reqs was unable to prove to its satisfaction that, for each | |
71 | jump target location, the stack will have the same height whether | |
72 | that location is reached via a jump or by straight execution. */ | |
73 | agent_flaw_height_mismatch, | |
74 | ||
75 | /* ax_reqs was unable to prove that every instruction following | |
76 | an unconditional jump was the target of some other jump. */ | |
77 | agent_flaw_hole | |
78 | }; | |
79 | ||
c906108c SS |
80 | /* Agent expression data structures. */ |
81 | ||
82 | /* The type of an element of the agent expression stack. | |
83 | The bytecode operation indicates which element we should access; | |
84 | the value itself has no typing information. GDB generates all | |
85 | bytecode streams, so we don't have to worry about type errors. */ | |
86 | ||
c5aa993b JM |
87 | union agent_val |
88 | { | |
89 | LONGEST l; | |
90 | DOUBLEST d; | |
91 | }; | |
c906108c SS |
92 | |
93 | /* A buffer containing a agent expression. */ | |
c5aa993b JM |
94 | struct agent_expr |
95 | { | |
35c9c7ba | 96 | /* The bytes of the expression. */ |
c5aa993b | 97 | unsigned char *buf; |
35c9c7ba SS |
98 | |
99 | /* The number of bytecode in the expression. */ | |
100 | int len; | |
101 | ||
102 | /* Allocated space available currently. */ | |
103 | int size; | |
104 | ||
105 | /* The target architecture assumed to be in effect. */ | |
106 | struct gdbarch *gdbarch; | |
107 | ||
108 | /* The address to which the expression applies. */ | |
c5aa993b | 109 | CORE_ADDR scope; |
c906108c | 110 | |
35c9c7ba SS |
111 | /* If the following is not equal to agent_flaw_none, the rest of the |
112 | information in this structure is suspect. */ | |
113 | enum agent_flaws flaw; | |
114 | ||
115 | /* Number of elements left on stack at end; may be negative if expr | |
116 | only consumes elements. */ | |
117 | int final_height; | |
118 | ||
119 | /* Maximum and minimum stack height, relative to initial height. */ | |
120 | int max_height, min_height; | |
121 | ||
122 | /* Largest `ref' or `const' opcode used, in bits. Zero means the | |
123 | expression has no such instructions. */ | |
124 | int max_data_size; | |
125 | ||
126 | /* Bit vector of registers needed. Register R is needed iff | |
c906108c | 127 | |
35c9c7ba | 128 | reg_mask[R / 8] & (1 << (R % 8)) |
c906108c | 129 | |
35c9c7ba SS |
130 | is non-zero. Note! You may not assume that this bitmask is long |
131 | enough to hold bits for all the registers of the machine; the | |
132 | agent expression code has no idea how many registers the machine | |
133 | has. However, the bitmask is reg_mask_len bytes long, so the | |
134 | valid register numbers run from 0 to reg_mask_len * 8 - 1. | |
135 | ||
136 | Also note that this mask may contain registers that are needed | |
137 | for the original collection expression to work, but that are | |
138 | not referenced by any bytecode. This could, for example, occur | |
139 | when collecting a local variable allocated to a register; the | |
140 | compiler sets the mask bit and skips generating a bytecode whose | |
141 | result is going to be discarded anyway. | |
142 | */ | |
143 | int reg_mask_len; | |
144 | unsigned char *reg_mask; | |
145 | }; | |
c906108c | 146 | |
94d5e490 | 147 | /* The actual values of the various bytecode operations. */ |
c906108c | 148 | |
c5aa993b JM |
149 | enum agent_op |
150 | { | |
94d5e490 TT |
151 | #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE) \ |
152 | aop_ ## NAME = VALUE, | |
153 | #include "ax.def" | |
154 | #undef DEFOP | |
c5aa993b JM |
155 | aop_last |
156 | }; | |
157 | \f | |
c906108c SS |
158 | |
159 | ||
c906108c SS |
160 | /* Functions for building expressions. */ |
161 | ||
162 | /* Allocate a new, empty agent expression. */ | |
35c9c7ba | 163 | extern struct agent_expr *new_agent_expr (struct gdbarch *, CORE_ADDR); |
c906108c SS |
164 | |
165 | /* Free a agent expression. */ | |
a14ed312 | 166 | extern void free_agent_expr (struct agent_expr *); |
f23d52e0 | 167 | extern struct cleanup *make_cleanup_free_agent_expr (struct agent_expr *); |
c906108c SS |
168 | |
169 | /* Append a simple operator OP to EXPR. */ | |
a14ed312 | 170 | extern void ax_simple (struct agent_expr *EXPR, enum agent_op OP); |
c906108c | 171 | |
c7f96d2b TT |
172 | /* Append a pick operator to EXPR. DEPTH is the stack item to pick, |
173 | with 0 being top of stack. */ | |
174 | extern void ax_pick (struct agent_expr *EXPR, int DEPTH); | |
175 | ||
c906108c SS |
176 | /* Append the floating-point prefix, for the next bytecode. */ |
177 | #define ax_float(EXPR) (ax_simple ((EXPR), aop_float)) | |
178 | ||
179 | /* Append a sign-extension instruction to EXPR, to extend an N-bit value. */ | |
a14ed312 | 180 | extern void ax_ext (struct agent_expr *EXPR, int N); |
c906108c SS |
181 | |
182 | /* Append a zero-extension instruction to EXPR, to extend an N-bit value. */ | |
a14ed312 | 183 | extern void ax_zero_ext (struct agent_expr *EXPR, int N); |
c906108c SS |
184 | |
185 | /* Append a trace_quick instruction to EXPR, to record N bytes. */ | |
a14ed312 | 186 | extern void ax_trace_quick (struct agent_expr *EXPR, int N); |
c906108c SS |
187 | |
188 | /* Append a goto op to EXPR. OP is the actual op (must be aop_goto or | |
189 | aop_if_goto). We assume we don't know the target offset yet, | |
190 | because it's probably a forward branch, so we leave space in EXPR | |
191 | for the target, and return the offset in EXPR of that space, so we | |
192 | can backpatch it once we do know the target offset. Use ax_label | |
193 | to do the backpatching. */ | |
a14ed312 | 194 | extern int ax_goto (struct agent_expr *EXPR, enum agent_op OP); |
c906108c SS |
195 | |
196 | /* Suppose a given call to ax_goto returns some value PATCH. When you | |
197 | know the offset TARGET that goto should jump to, call | |
c5aa993b | 198 | ax_label (EXPR, PATCH, TARGET) |
c906108c | 199 | to patch TARGET into the ax_goto instruction. */ |
a14ed312 | 200 | extern void ax_label (struct agent_expr *EXPR, int patch, int target); |
c906108c SS |
201 | |
202 | /* Assemble code to push a constant on the stack. */ | |
a14ed312 KB |
203 | extern void ax_const_l (struct agent_expr *EXPR, LONGEST l); |
204 | extern void ax_const_d (struct agent_expr *EXPR, LONGEST d); | |
c906108c SS |
205 | |
206 | /* Assemble code to push the value of register number REG on the | |
207 | stack. */ | |
a14ed312 | 208 | extern void ax_reg (struct agent_expr *EXPR, int REG); |
f61e138d | 209 | |
35c9c7ba SS |
210 | /* Add the given register to the register mask of the expression. */ |
211 | extern void ax_reg_mask (struct agent_expr *ax, int reg); | |
212 | ||
f61e138d SS |
213 | /* Assemble code to operate on a trace state variable. */ |
214 | extern void ax_tsv (struct agent_expr *expr, enum agent_op op, int num); | |
c906108c | 215 | \f |
c5aa993b | 216 | |
c906108c SS |
217 | /* Functions for printing out expressions, and otherwise debugging |
218 | things. */ | |
219 | ||
220 | /* Disassemble the expression EXPR, writing to F. */ | |
d9fcf2fb | 221 | extern void ax_print (struct ui_file *f, struct agent_expr * EXPR); |
c906108c SS |
222 | |
223 | /* An entry in the opcode map. */ | |
c5aa993b JM |
224 | struct aop_map |
225 | { | |
c906108c | 226 | |
c5aa993b JM |
227 | /* The name of the opcode. Null means that this entry is not a |
228 | valid opcode --- a hole in the opcode space. */ | |
5f1e6f19 | 229 | const char *name; |
c906108c | 230 | |
c5aa993b JM |
231 | /* All opcodes take no operands from the bytecode stream, or take |
232 | unsigned integers of various sizes. If this is a positive number | |
233 | n, then the opcode is followed by an n-byte operand, which should | |
234 | be printed as an unsigned integer. If this is zero, then the | |
235 | opcode takes no operands from the bytecode stream. | |
c906108c | 236 | |
c5aa993b JM |
237 | If we get more complicated opcodes in the future, don't add other |
238 | magic values of this; that's a crock. Add an `enum encoding' | |
239 | field to this, or something like that. */ | |
240 | int op_size; | |
c906108c | 241 | |
c5aa993b JM |
242 | /* The size of the data operated upon, in bits, for bytecodes that |
243 | care about that (ref and const). Zero for all others. */ | |
244 | int data_size; | |
c906108c | 245 | |
c5aa993b JM |
246 | /* Number of stack elements consumed, and number produced. */ |
247 | int consumed, produced; | |
248 | }; | |
c906108c SS |
249 | |
250 | /* Map of the bytecodes, indexed by bytecode number. */ | |
251 | extern struct aop_map aop_map[]; | |
252 | ||
35c9c7ba | 253 | /* Given an agent expression AX, analyze and update its requirements. */ |
c906108c | 254 | |
35c9c7ba | 255 | extern void ax_reqs (struct agent_expr *ax); |
c906108c SS |
256 | |
257 | #endif /* AGENTEXPR_H */ |