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c906108c SS |
1 | /* Functions for manipulating expressions designed to be executed on the agent |
2 | Copyright 1998 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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 | |
18 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
19 | ||
c906108c SS |
20 | /* Despite what the above comment says about this file being part of |
21 | GDB, we would like to keep these functions free of GDB | |
22 | dependencies, since we want to be able to use them in contexts | |
23 | outside of GDB (test suites, the stub, etc.) */ | |
24 | ||
25 | #include "defs.h" | |
26 | #include "ax.h" | |
27 | ||
7a292a7a SS |
28 | #include "value.h" |
29 | ||
392a587b JM |
30 | static void grow_expr PARAMS ((struct agent_expr *x, int n)); |
31 | ||
32 | static void append_const PARAMS ((struct agent_expr *x, LONGEST val, int n)); | |
33 | ||
34 | static LONGEST read_const PARAMS ((struct agent_expr *x, int o, int n)); | |
35 | ||
36 | static void generic_ext PARAMS ((struct agent_expr *x, enum agent_op op, int n)); | |
c906108c SS |
37 | \f |
38 | /* Functions for building expressions. */ | |
39 | ||
40 | /* Allocate a new, empty agent expression. */ | |
41 | struct agent_expr * | |
42 | new_agent_expr (scope) | |
43 | CORE_ADDR scope; | |
44 | { | |
45 | struct agent_expr *x = xmalloc (sizeof (*x)); | |
46 | x->len = 0; | |
47 | x->size = 1; /* Change this to a larger value once | |
48 | reallocation code is tested. */ | |
49 | x->buf = xmalloc (x->size); | |
50 | x->scope = scope; | |
51 | ||
52 | return x; | |
53 | } | |
54 | ||
55 | /* Free a agent expression. */ | |
56 | void | |
57 | free_agent_expr (x) | |
58 | struct agent_expr *x; | |
59 | { | |
60 | free (x->buf); | |
61 | free (x); | |
62 | } | |
63 | ||
64 | ||
65 | /* Make sure that X has room for at least N more bytes. This doesn't | |
66 | affect the length, just the allocated size. */ | |
67 | static void | |
68 | grow_expr (x, n) | |
69 | struct agent_expr *x; | |
70 | int n; | |
71 | { | |
72 | if (x->len + n > x->size) | |
73 | { | |
74 | x->size *= 2; | |
75 | if (x->size < x->len + n) | |
76 | x->size = x->len + n + 10; | |
77 | x->buf = xrealloc (x->buf, x->size); | |
78 | } | |
79 | } | |
80 | ||
81 | ||
82 | /* Append the low N bytes of VAL as an N-byte integer to the | |
83 | expression X, in big-endian order. */ | |
84 | static void | |
85 | append_const (x, val, n) | |
86 | struct agent_expr *x; | |
87 | LONGEST val; | |
88 | int n; | |
89 | { | |
90 | int i; | |
91 | ||
92 | grow_expr (x, n); | |
93 | for (i = n - 1; i >= 0; i--) | |
94 | { | |
95 | x->buf[x->len + i] = val & 0xff; | |
96 | val >>= 8; | |
97 | } | |
98 | x->len += n; | |
99 | } | |
100 | ||
101 | ||
102 | /* Extract an N-byte big-endian unsigned integer from expression X at | |
103 | offset O. */ | |
104 | static LONGEST | |
105 | read_const (x, o, n) | |
106 | struct agent_expr *x; | |
107 | int o, n; | |
108 | { | |
109 | int i; | |
110 | LONGEST accum = 0; | |
111 | ||
112 | /* Make sure we're not reading off the end of the expression. */ | |
113 | if (o + n > x->len) | |
114 | error ("GDB bug: ax-general.c (read_const): incomplete constant"); | |
115 | ||
116 | for (i = 0; i < n; i++) | |
117 | accum = (accum << 8) | x->buf[o + i]; | |
118 | ||
119 | return accum; | |
120 | } | |
121 | ||
122 | ||
123 | /* Append a simple operator OP to EXPR. */ | |
124 | void | |
125 | ax_simple (x, op) | |
126 | struct agent_expr *x; | |
127 | enum agent_op op; | |
128 | { | |
129 | grow_expr (x, 1); | |
130 | x->buf[x->len++] = op; | |
131 | } | |
132 | ||
133 | ||
134 | /* Append a sign-extension or zero-extension instruction to EXPR, to | |
135 | extend an N-bit value. */ | |
136 | static void | |
137 | generic_ext (x, op, n) | |
138 | struct agent_expr *x; | |
139 | enum agent_op op; | |
140 | int n; | |
141 | { | |
142 | /* N must fit in a byte. */ | |
143 | if (n < 0 || n > 255) | |
144 | error ("GDB bug: ax-general.c (generic_ext): bit count out of range"); | |
145 | /* That had better be enough range. */ | |
146 | if (sizeof (LONGEST) * 8 > 255) | |
147 | error ("GDB bug: ax-general.c (generic_ext): opcode has inadequate range"); | |
148 | ||
149 | grow_expr (x, 2); | |
150 | x->buf[x->len++] = op; | |
151 | x->buf[x->len++] = n; | |
152 | } | |
153 | ||
154 | ||
155 | /* Append a sign-extension instruction to EXPR, to extend an N-bit value. */ | |
156 | void | |
157 | ax_ext (x, n) | |
158 | struct agent_expr *x; | |
159 | int n; | |
160 | { | |
161 | generic_ext (x, aop_ext, n); | |
162 | } | |
163 | ||
164 | ||
165 | /* Append a zero-extension instruction to EXPR, to extend an N-bit value. */ | |
166 | void | |
167 | ax_zero_ext (x, n) | |
168 | struct agent_expr *x; | |
169 | int n; | |
170 | { | |
171 | generic_ext (x, aop_zero_ext, n); | |
172 | } | |
173 | ||
174 | ||
175 | /* Append a trace_quick instruction to EXPR, to record N bytes. */ | |
176 | void | |
177 | ax_trace_quick (x, n) | |
178 | struct agent_expr *x; | |
179 | int n; | |
180 | { | |
181 | /* N must fit in a byte. */ | |
182 | if (n < 0 || n > 255) | |
183 | error ("GDB bug: ax-general.c (ax_trace_quick): size out of range for trace_quick"); | |
184 | ||
185 | grow_expr (x, 2); | |
186 | x->buf[x->len++] = aop_trace_quick; | |
187 | x->buf[x->len++] = n; | |
188 | } | |
189 | ||
190 | ||
191 | /* Append a goto op to EXPR. OP is the actual op (must be aop_goto or | |
192 | aop_if_goto). We assume we don't know the target offset yet, | |
193 | because it's probably a forward branch, so we leave space in EXPR | |
194 | for the target, and return the offset in EXPR of that space, so we | |
195 | can backpatch it once we do know the target offset. Use ax_label | |
196 | to do the backpatching. */ | |
197 | int ax_goto (x, op) | |
198 | struct agent_expr *x; | |
199 | enum agent_op op; | |
200 | { | |
201 | grow_expr (x, 3); | |
202 | x->buf[x->len + 0] = op; | |
203 | x->buf[x->len + 1] = 0xff; | |
204 | x->buf[x->len + 2] = 0xff; | |
205 | x->len += 3; | |
206 | return x->len - 2; | |
207 | } | |
208 | ||
209 | /* Suppose a given call to ax_goto returns some value PATCH. When you | |
210 | know the offset TARGET that goto should jump to, call | |
211 | ax_label (EXPR, PATCH, TARGET) | |
212 | to patch TARGET into the ax_goto instruction. */ | |
213 | void | |
214 | ax_label (x, patch, target) | |
215 | struct agent_expr *x; | |
216 | int patch; | |
217 | int target; | |
218 | { | |
219 | /* Make sure the value is in range. Don't accept 0xffff as an | |
220 | offset; that's our magic sentinel value for unpatched branches. */ | |
221 | if (target < 0 || target >= 0xffff) | |
222 | error ("GDB bug: ax-general.c (ax_label): label target out of range"); | |
223 | ||
224 | x->buf[patch] = (target >> 8) & 0xff; | |
225 | x->buf[patch + 1] = target & 0xff; | |
226 | } | |
227 | ||
228 | ||
229 | /* Assemble code to push a constant on the stack. */ | |
230 | void | |
231 | ax_const_l (x, l) | |
232 | struct agent_expr *x; | |
233 | LONGEST l; | |
234 | { | |
235 | static enum agent_op ops[] | |
236 | = { aop_const8, aop_const16, aop_const32, aop_const64 }; | |
237 | int size; | |
238 | int op; | |
239 | ||
240 | /* How big is the number? 'op' keeps track of which opcode to use. | |
241 | Notice that we don't really care whether the original number was | |
242 | signed or unsigned; we always reproduce the value exactly, and | |
243 | use the shortest representation. */ | |
244 | for (op = 0, size = 8; size < 64; size *= 2, op++) | |
245 | if (-((LONGEST) 1 << size) <= l && l < ((LONGEST) 1 << size)) | |
246 | break; | |
247 | ||
248 | /* Emit the right opcode... */ | |
249 | ax_simple (x, ops[op]); | |
250 | ||
251 | /* Emit the low SIZE bytes as an unsigned number. We know that | |
252 | sign-extending this will yield l. */ | |
253 | append_const (x, l, size / 8); | |
254 | ||
255 | /* Now, if it was negative, and not full-sized, sign-extend it. */ | |
256 | if (l < 0 && size < 64) | |
257 | ax_ext (x, size); | |
258 | } | |
259 | ||
260 | ||
261 | void | |
262 | ax_const_d (x, d) | |
263 | struct agent_expr *x; | |
264 | LONGEST d; | |
265 | { | |
266 | /* FIXME: floating-point support not present yet. */ | |
267 | error ("GDB bug: ax-general.c (ax_const_d): floating point not supported yet"); | |
268 | } | |
269 | ||
270 | ||
271 | /* Assemble code to push the value of register number REG on the | |
272 | stack. */ | |
273 | void ax_reg (x, reg) | |
274 | struct agent_expr *x; | |
275 | int reg; | |
276 | { | |
277 | /* Make sure the register number is in range. */ | |
278 | if (reg < 0 || reg > 0xffff) | |
279 | error ("GDB bug: ax-general.c (ax_reg): register number out of range"); | |
280 | grow_expr (x, 3); | |
281 | x->buf[x->len ] = aop_reg; | |
282 | x->buf[x->len + 1] = (reg >> 8) & 0xff; | |
283 | x->buf[x->len + 2] = (reg ) & 0xff; | |
284 | x->len += 3; | |
285 | } | |
286 | ||
287 | ||
288 | \f | |
289 | /* Functions for disassembling agent expressions, and otherwise | |
290 | debugging the expression compiler. */ | |
291 | ||
292 | struct aop_map aop_map[] = { | |
293 | { 0, 0, 0, 0, 0 }, | |
294 | { "float", 0, 0, 0, 0 }, /* 0x01 */ | |
295 | { "add", 0, 0, 2, 1 }, /* 0x02 */ | |
296 | { "sub", 0, 0, 2, 1 }, /* 0x03 */ | |
297 | { "mul", 0, 0, 2, 1 }, /* 0x04 */ | |
298 | { "div_signed", 0, 0, 2, 1 }, /* 0x05 */ | |
299 | { "div_unsigned", 0, 0, 2, 1 }, /* 0x06 */ | |
300 | { "rem_signed", 0, 0, 2, 1 }, /* 0x07 */ | |
301 | { "rem_unsigned", 0, 0, 2, 1 }, /* 0x08 */ | |
302 | { "lsh", 0, 0, 2, 1 }, /* 0x09 */ | |
303 | { "rsh_signed", 0, 0, 2, 1 }, /* 0x0a */ | |
304 | { "rsh_unsigned", 0, 0, 2, 1 }, /* 0x0b */ | |
305 | { "trace", 0, 0, 2, 0 }, /* 0x0c */ | |
306 | { "trace_quick", 1, 0, 1, 1 }, /* 0x0d */ | |
307 | { "log_not", 0, 0, 1, 1 }, /* 0x0e */ | |
308 | { "bit_and", 0, 0, 2, 1 }, /* 0x0f */ | |
309 | { "bit_or", 0, 0, 2, 1 }, /* 0x10 */ | |
310 | { "bit_xor", 0, 0, 2, 1 }, /* 0x11 */ | |
311 | { "bit_not", 0, 0, 1, 1 }, /* 0x12 */ | |
312 | { "equal", 0, 0, 2, 1 }, /* 0x13 */ | |
313 | { "less_signed", 0, 0, 2, 1 }, /* 0x14 */ | |
314 | { "less_unsigned", 0, 0, 2, 1 }, /* 0x15 */ | |
315 | { "ext", 1, 0, 1, 1 }, /* 0x16 */ | |
316 | { "ref8", 0, 8, 1, 1 }, /* 0x17 */ | |
317 | { "ref16", 0, 16, 1, 1 }, /* 0x18 */ | |
318 | { "ref32", 0, 32, 1, 1 }, /* 0x19 */ | |
319 | { "ref64", 0, 64, 1, 1 }, /* 0x1a */ | |
320 | { "ref_float", 0, 0, 1, 1 }, /* 0x1b */ | |
321 | { "ref_double", 0, 0, 1, 1 }, /* 0x1c */ | |
322 | { "ref_long_double", 0, 0, 1, 1 }, /* 0x1d */ | |
323 | { "l_to_d", 0, 0, 1, 1 }, /* 0x1e */ | |
324 | { "d_to_l", 0, 0, 1, 1 }, /* 0x1f */ | |
325 | { "if_goto", 2, 0, 1, 0 }, /* 0x20 */ | |
326 | { "goto", 2, 0, 0, 0 }, /* 0x21 */ | |
327 | { "const8", 1, 8, 0, 1 }, /* 0x22 */ | |
328 | { "const16", 2, 16, 0, 1 }, /* 0x23 */ | |
329 | { "const32", 4, 32, 0, 1 }, /* 0x24 */ | |
330 | { "const64", 8, 64, 0, 1 }, /* 0x25 */ | |
331 | { "reg", 2, 0, 0, 1 }, /* 0x26 */ | |
332 | { "end", 0, 0, 0, 0 }, /* 0x27 */ | |
333 | { "dup", 0, 0, 1, 2 }, /* 0x28 */ | |
334 | { "pop", 0, 0, 1, 0 }, /* 0x29 */ | |
335 | { "zero_ext", 1, 0, 1, 1 }, /* 0x2a */ | |
336 | { "swap", 0, 0, 2, 2 }, /* 0x2b */ | |
337 | { 0, 0, 0, 0, 0 }, /* 0x2c */ | |
338 | { 0, 0, 0, 0, 0 }, /* 0x2d */ | |
339 | { 0, 0, 0, 0, 0 }, /* 0x2e */ | |
340 | { 0, 0, 0, 0, 0 }, /* 0x2f */ | |
341 | { "trace16", 2, 0, 1, 1 }, /* 0x30 */ | |
342 | }; | |
343 | ||
344 | ||
345 | /* Disassemble the expression EXPR, writing to F. */ | |
346 | void | |
347 | ax_print (f, x) | |
348 | GDB_FILE *f; | |
349 | struct agent_expr *x; | |
350 | { | |
351 | int i; | |
352 | int is_float = 0; | |
353 | ||
354 | /* Check the size of the name array against the number of entries in | |
355 | the enum, to catch additions that people didn't sync. */ | |
356 | if ((sizeof (aop_map) / sizeof (aop_map[0])) | |
357 | != aop_last) | |
358 | error ("GDB bug: ax-general.c (ax_print): opcode map out of sync"); | |
359 | ||
360 | for (i = 0; i < x->len; ) | |
361 | { | |
362 | enum agent_op op = x->buf[i]; | |
363 | ||
364 | if (op >= (sizeof (aop_map) / sizeof (aop_map[0])) | |
365 | || ! aop_map[op].name) | |
366 | { | |
367 | fprintf_filtered (f, "%3d <bad opcode %02x>\n", i, op); | |
368 | i++; | |
369 | continue; | |
370 | } | |
371 | if (i + 1 + aop_map[op].op_size > x->len) | |
372 | { | |
373 | fprintf_filtered (f, "%3d <incomplete opcode %s>\n", | |
374 | i, aop_map[op].name); | |
375 | break; | |
376 | } | |
377 | ||
378 | fprintf_filtered (f, "%3d %s", i, aop_map[op].name); | |
379 | if (aop_map[op].op_size > 0) | |
380 | { | |
381 | fputs_filtered (" ", f); | |
382 | ||
383 | print_longest (f, 'd', 0, | |
384 | read_const (x, i + 1, aop_map[op].op_size)); | |
385 | } | |
386 | fprintf_filtered (f, "\n"); | |
387 | i += 1 + aop_map[op].op_size; | |
388 | ||
389 | is_float = (op == aop_float); | |
390 | } | |
391 | } | |
392 | ||
393 | ||
394 | /* Given an agent expression AX, fill in an agent_reqs structure REQS | |
395 | describing it. */ | |
396 | void | |
397 | ax_reqs (ax, reqs) | |
398 | struct agent_expr *ax; | |
399 | struct agent_reqs *reqs; | |
400 | { | |
401 | int i; | |
402 | int height; | |
403 | ||
404 | /* Bit vector for registers used. */ | |
405 | int reg_mask_len = 1; | |
406 | unsigned char *reg_mask = xmalloc (reg_mask_len * sizeof (reg_mask[0])); | |
407 | ||
408 | /* Jump target table. targets[i] is non-zero iff there is a jump to | |
409 | offset i. */ | |
410 | char *targets = (char *) alloca (ax->len * sizeof (targets[0])); | |
411 | ||
412 | /* Instruction boundary table. boundary[i] is non-zero iff an | |
413 | instruction starts at offset i. */ | |
414 | char *boundary = (char *) alloca (ax->len * sizeof (boundary[0])); | |
415 | ||
416 | /* Stack height record. iff either targets[i] or boundary[i] is | |
417 | non-zero, heights[i] is the height the stack should have before | |
418 | executing the bytecode at that point. */ | |
419 | int *heights = (int *) alloca (ax->len * sizeof (heights[0])); | |
420 | ||
421 | /* Pointer to a description of the present op. */ | |
422 | struct aop_map *op; | |
423 | ||
424 | memset (reg_mask, 0, reg_mask_len * sizeof (reg_mask[0])); | |
425 | memset (targets, 0, ax->len * sizeof (targets[0])); | |
426 | memset (boundary, 0, ax->len * sizeof (boundary[0])); | |
427 | ||
428 | reqs->max_height = reqs->min_height = height = 0; | |
429 | reqs->flaw = agent_flaw_none; | |
430 | reqs->max_data_size = 0; | |
431 | ||
432 | for (i = 0; i < ax->len; i += 1 + op->op_size) | |
433 | { | |
434 | if (ax->buf[i] > (sizeof (aop_map) / sizeof (aop_map[0]))) | |
435 | { | |
436 | reqs->flaw = agent_flaw_bad_instruction; | |
437 | free (reg_mask); | |
438 | return; | |
439 | } | |
440 | ||
441 | op = &aop_map[ax->buf[i]]; | |
442 | ||
443 | if (! op->name) | |
444 | { | |
445 | reqs->flaw = agent_flaw_bad_instruction; | |
446 | free (reg_mask); | |
447 | return; | |
448 | } | |
449 | ||
450 | if (i + 1 + op->op_size > ax->len) | |
451 | { | |
452 | reqs->flaw = agent_flaw_incomplete_instruction; | |
453 | free (reg_mask); | |
454 | return; | |
455 | } | |
456 | ||
457 | /* If this instruction is a jump target, does the current stack | |
458 | height match the stack height at the jump source? */ | |
459 | if (targets[i] && (heights[i] != height)) | |
460 | { | |
461 | reqs->flaw = agent_flaw_height_mismatch; | |
462 | free (reg_mask); | |
463 | return; | |
464 | } | |
465 | ||
466 | boundary[i] = 1; | |
467 | heights[i] = height; | |
468 | ||
469 | height -= op->consumed; | |
470 | if (height < reqs->min_height) | |
471 | reqs->min_height = height; | |
472 | height += op->produced; | |
473 | if (height > reqs->max_height) | |
474 | reqs->max_height = height; | |
475 | ||
476 | if (op->data_size > reqs->max_data_size) | |
477 | reqs->max_data_size = op->data_size; | |
478 | ||
479 | /* For jump instructions, check that the target is a valid | |
480 | offset. If it is, record the fact that that location is a | |
481 | jump target, and record the height we expect there. */ | |
482 | if (aop_goto == op - aop_map | |
483 | || aop_if_goto == op - aop_map) | |
484 | { | |
485 | int target = read_const (ax, i + 1, 2); | |
486 | if (target < 0 || target >= ax->len) | |
487 | { | |
488 | reqs->flaw = agent_flaw_bad_jump; | |
489 | free (reg_mask); | |
490 | return; | |
491 | } | |
492 | /* Have we already found other jumps to the same location? */ | |
493 | else if (targets[target]) | |
494 | { | |
495 | if (heights[i] != height) | |
496 | { | |
497 | reqs->flaw = agent_flaw_height_mismatch; | |
498 | free (reg_mask); | |
499 | return; | |
500 | } | |
501 | } | |
502 | else | |
503 | { | |
504 | targets[target] = 1; | |
505 | heights[target] = height; | |
506 | } | |
507 | } | |
508 | ||
509 | /* For unconditional jumps with a successor, check that the | |
510 | successor is a target, and pick up its stack height. */ | |
511 | if (aop_goto == op - aop_map | |
512 | && i + 3 < ax->len) | |
513 | { | |
514 | if (! targets[i + 3]) | |
515 | { | |
516 | reqs->flaw = agent_flaw_hole; | |
517 | free (reg_mask); | |
518 | return; | |
519 | } | |
520 | ||
521 | height = heights[i + 3]; | |
522 | } | |
523 | ||
524 | /* For reg instructions, record the register in the bit mask. */ | |
525 | if (aop_reg == op - aop_map) | |
526 | { | |
527 | int reg = read_const (ax, i + 1, 2); | |
528 | int byte = reg / 8; | |
529 | ||
530 | /* Grow the bit mask if necessary. */ | |
531 | if (byte >= reg_mask_len) | |
532 | { | |
533 | /* It's not appropriate to double here. This isn't a | |
534 | string buffer. */ | |
535 | int new_len = byte + 1; | |
536 | reg_mask = xrealloc (reg_mask, | |
537 | new_len * sizeof (reg_mask[0])); | |
538 | memset (reg_mask + reg_mask_len, 0, | |
539 | (new_len - reg_mask_len) * sizeof (reg_mask[0])); | |
540 | reg_mask_len = new_len; | |
541 | } | |
542 | ||
543 | reg_mask[byte] |= 1 << (reg % 8); | |
544 | } | |
545 | } | |
546 | ||
547 | /* Check that all the targets are on boundaries. */ | |
548 | for (i = 0; i < ax->len; i++) | |
549 | if (targets[i] && !boundary[i]) | |
550 | { | |
551 | reqs->flaw = agent_flaw_bad_jump; | |
552 | free (reg_mask); | |
553 | return; | |
554 | } | |
555 | ||
556 | reqs->final_height = height; | |
557 | reqs->reg_mask_len = reg_mask_len; | |
558 | reqs->reg_mask = reg_mask; | |
559 | } |