Commit | Line | Data |
---|---|---|
c906108c SS |
1 | /* GDB-specific functions for operating on agent expressions |
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 | #include "defs.h" |
21 | #include "symtab.h" | |
22 | #include "symfile.h" | |
23 | #include "gdbtypes.h" | |
24 | #include "value.h" | |
25 | #include "expression.h" | |
26 | #include "command.h" | |
27 | #include "gdbcmd.h" | |
28 | #include "frame.h" | |
29 | #include "target.h" | |
30 | #include "ax.h" | |
31 | #include "ax-gdb.h" | |
32 | ||
33 | /* Probably the best way to read this file is to start with the types | |
34 | and enums in ax-gdb.h, and then look at gen_expr, towards the | |
35 | bottom; that's the main function that looks at the GDB expressions | |
36 | and calls everything else to generate code. | |
37 | ||
38 | I'm beginning to wonder whether it wouldn't be nicer to internally | |
39 | generate trees, with types, and then spit out the bytecode in | |
40 | linear form afterwards; we could generate fewer `swap', `ext', and | |
41 | `zero_ext' bytecodes that way; it would make good constant folding | |
42 | easier, too. But at the moment, I think we should be willing to | |
43 | pay for the simplicity of this code with less-than-optimal bytecode | |
44 | strings. | |
45 | ||
46 | Remember, "GBD" stands for "Great Britain, Dammit!" So be careful. */ | |
47 | ||
48 | ||
49 | \f | |
50 | /* Prototypes for local functions. */ | |
51 | ||
52 | /* There's a standard order to the arguments of these functions: | |
53 | union exp_element ** --- pointer into expression | |
54 | struct agent_expr * --- agent expression buffer to generate code into | |
55 | struct axs_value * --- describes value left on top of stack */ | |
56 | ||
57 | static struct value *const_var_ref PARAMS ((struct symbol *var)); | |
58 | static struct value *const_expr PARAMS ((union exp_element **pc)); | |
59 | static struct value *maybe_const_expr PARAMS ((union exp_element **pc)); | |
60 | ||
61 | static void gen_traced_pop PARAMS ((struct agent_expr *, struct axs_value *)); | |
62 | ||
63 | static void gen_sign_extend PARAMS ((struct agent_expr *, struct type *)); | |
64 | static void gen_extend PARAMS ((struct agent_expr *, struct type *)); | |
65 | static void gen_fetch PARAMS ((struct agent_expr *, struct type *)); | |
66 | static void gen_left_shift PARAMS ((struct agent_expr *, int)); | |
67 | ||
68 | ||
69 | static void gen_frame_args_address PARAMS ((struct agent_expr *)); | |
70 | static void gen_frame_locals_address PARAMS ((struct agent_expr *)); | |
71 | static void gen_offset PARAMS ((struct agent_expr *ax, int offset)); | |
72 | static void gen_sym_offset PARAMS ((struct agent_expr *, struct symbol *)); | |
73 | static void gen_var_ref PARAMS ((struct agent_expr *ax, | |
74 | struct axs_value *value, | |
75 | struct symbol *var)); | |
76 | ||
77 | ||
78 | static void gen_int_literal PARAMS ((struct agent_expr *ax, | |
79 | struct axs_value *value, | |
80 | LONGEST k, struct type *type)); | |
81 | ||
82 | ||
83 | static void require_rvalue PARAMS ((struct agent_expr *ax, | |
84 | struct axs_value *value)); | |
85 | static void gen_usual_unary PARAMS ((struct agent_expr *ax, | |
86 | struct axs_value *value)); | |
87 | static int type_wider_than PARAMS ((struct type *type1, | |
88 | struct type *type2)); | |
89 | static struct type *max_type PARAMS ((struct type *type1, | |
90 | struct type *type2)); | |
91 | static void gen_conversion PARAMS ((struct agent_expr *ax, | |
92 | struct type *from, | |
93 | struct type *to)); | |
94 | static int is_nontrivial_conversion PARAMS ((struct type *from, | |
95 | struct type *to)); | |
96 | static void gen_usual_arithmetic PARAMS ((struct agent_expr *ax, | |
97 | struct axs_value *value1, | |
98 | struct axs_value *value2)); | |
99 | static void gen_integral_promotions PARAMS ((struct agent_expr *ax, | |
100 | struct axs_value *value)); | |
101 | static void gen_cast PARAMS ((struct agent_expr *ax, | |
102 | struct axs_value *value, | |
103 | struct type *type)); | |
104 | static void gen_scale PARAMS ((struct agent_expr *ax, | |
105 | enum agent_op op, | |
106 | struct type *type)); | |
107 | static void gen_add PARAMS ((struct agent_expr *ax, | |
108 | struct axs_value *value, | |
109 | struct axs_value *value1, | |
110 | struct axs_value *value2, | |
111 | char *name)); | |
112 | static void gen_sub PARAMS ((struct agent_expr *ax, | |
113 | struct axs_value *value, | |
114 | struct axs_value *value1, | |
115 | struct axs_value *value2)); | |
116 | static void gen_binop PARAMS ((struct agent_expr *ax, | |
117 | struct axs_value *value, | |
118 | struct axs_value *value1, | |
119 | struct axs_value *value2, | |
120 | enum agent_op op, | |
121 | enum agent_op op_unsigned, | |
122 | int may_carry, | |
123 | char *name)); | |
124 | static void gen_logical_not PARAMS ((struct agent_expr *ax, | |
125 | struct axs_value *value)); | |
126 | static void gen_complement PARAMS ((struct agent_expr *ax, | |
127 | struct axs_value *value)); | |
128 | static void gen_deref PARAMS ((struct agent_expr *, struct axs_value *)); | |
129 | static void gen_address_of PARAMS ((struct agent_expr *, struct axs_value *)); | |
130 | static int find_field PARAMS ((struct type *type, char *name)); | |
131 | static void gen_bitfield_ref PARAMS ((struct agent_expr *ax, | |
132 | struct axs_value *value, | |
133 | struct type *type, | |
134 | int start, int end)); | |
135 | static void gen_struct_ref PARAMS ((struct agent_expr *ax, | |
136 | struct axs_value *value, | |
137 | char *field, | |
138 | char *operator_name, | |
139 | char *operand_name)); | |
140 | static void gen_repeat PARAMS ((union exp_element **pc, | |
141 | struct agent_expr *ax, | |
142 | struct axs_value *value)); | |
143 | static void gen_sizeof PARAMS ((union exp_element **pc, | |
144 | struct agent_expr *ax, | |
145 | struct axs_value *value)); | |
146 | static void gen_expr PARAMS ((union exp_element **pc, | |
147 | struct agent_expr *ax, | |
148 | struct axs_value *value)); | |
149 | ||
150 | static void print_axs_value PARAMS ((GDB_FILE *f, struct axs_value *value)); | |
151 | static void agent_command PARAMS ((char *exp, int from_tty)); | |
152 | ||
153 | \f | |
154 | /* Detecting constant expressions. */ | |
155 | ||
156 | /* If the variable reference at *PC is a constant, return its value. | |
157 | Otherwise, return zero. | |
158 | ||
159 | Hey, Wally! How can a variable reference be a constant? | |
160 | ||
161 | Well, Beav, this function really handles the OP_VAR_VALUE operator, | |
162 | not specifically variable references. GDB uses OP_VAR_VALUE to | |
163 | refer to any kind of symbolic reference: function names, enum | |
164 | elements, and goto labels are all handled through the OP_VAR_VALUE | |
165 | operator, even though they're constants. It makes sense given the | |
166 | situation. | |
167 | ||
168 | Gee, Wally, don'cha wonder sometimes if data representations that | |
169 | subvert commonly accepted definitions of terms in favor of heavily | |
170 | context-specific interpretations are really just a tool of the | |
171 | programming hegemony to preserve their power and exclude the | |
172 | proletariat? */ | |
173 | ||
174 | static struct value * | |
175 | const_var_ref (var) | |
176 | struct symbol *var; | |
177 | { | |
178 | struct type *type = SYMBOL_TYPE (var); | |
179 | ||
180 | switch (SYMBOL_CLASS (var)) | |
181 | { | |
182 | case LOC_CONST: | |
183 | return value_from_longest (type, (LONGEST) SYMBOL_VALUE (var)); | |
184 | ||
185 | case LOC_LABEL: | |
186 | return value_from_longest (type, (LONGEST) SYMBOL_VALUE_ADDRESS (var)); | |
187 | ||
188 | default: | |
189 | return 0; | |
190 | } | |
191 | } | |
192 | ||
193 | ||
194 | /* If the expression starting at *PC has a constant value, return it. | |
195 | Otherwise, return zero. If we return a value, then *PC will be | |
196 | advanced to the end of it. If we return zero, *PC could be | |
197 | anywhere. */ | |
198 | static struct value * | |
199 | const_expr (pc) | |
200 | union exp_element **pc; | |
201 | { | |
202 | enum exp_opcode op = (*pc)->opcode; | |
203 | struct value *v1; | |
204 | ||
205 | switch (op) | |
206 | { | |
207 | case OP_LONG: | |
208 | { | |
209 | struct type *type = (*pc)[1].type; | |
210 | LONGEST k = (*pc)[2].longconst; | |
211 | (*pc) += 4; | |
212 | return value_from_longest (type, k); | |
213 | } | |
214 | ||
215 | case OP_VAR_VALUE: | |
216 | { | |
217 | struct value *v = const_var_ref ((*pc)[2].symbol); | |
218 | (*pc) += 4; | |
219 | return v; | |
220 | } | |
221 | ||
222 | /* We could add more operators in here. */ | |
223 | ||
224 | case UNOP_NEG: | |
225 | (*pc)++; | |
226 | v1 = const_expr (pc); | |
227 | if (v1) | |
228 | return value_neg (v1); | |
229 | else | |
230 | return 0; | |
231 | ||
232 | default: | |
233 | return 0; | |
234 | } | |
235 | } | |
236 | ||
237 | ||
238 | /* Like const_expr, but guarantee also that *PC is undisturbed if the | |
239 | expression is not constant. */ | |
240 | static struct value * | |
241 | maybe_const_expr (pc) | |
242 | union exp_element **pc; | |
243 | { | |
244 | union exp_element *tentative_pc = *pc; | |
245 | struct value *v = const_expr (&tentative_pc); | |
246 | ||
247 | /* If we got a value, then update the real PC. */ | |
248 | if (v) | |
249 | *pc = tentative_pc; | |
250 | ||
251 | return v; | |
252 | } | |
253 | ||
254 | \f | |
255 | /* Generating bytecode from GDB expressions: general assumptions */ | |
256 | ||
257 | /* Here are a few general assumptions made throughout the code; if you | |
258 | want to make a change that contradicts one of these, then you'd | |
259 | better scan things pretty thoroughly. | |
260 | ||
261 | - We assume that all values occupy one stack element. For example, | |
262 | sometimes we'll swap to get at the left argument to a binary | |
263 | operator. If we decide that void values should occupy no stack | |
264 | elements, or that synthetic arrays (whose size is determined at | |
265 | run time, created by the `@' operator) should occupy two stack | |
266 | elements (address and length), then this will cause trouble. | |
267 | ||
268 | - We assume the stack elements are infinitely wide, and that we | |
269 | don't have to worry what happens if the user requests an | |
270 | operation that is wider than the actual interpreter's stack. | |
271 | That is, it's up to the interpreter to handle directly all the | |
272 | integer widths the user has access to. (Woe betide the language | |
273 | with bignums!) | |
274 | ||
275 | - We don't support side effects. Thus, we don't have to worry about | |
276 | GCC's generalized lvalues, function calls, etc. | |
277 | ||
278 | - We don't support floating point. Many places where we switch on | |
279 | some type don't bother to include cases for floating point; there | |
280 | may be even more subtle ways this assumption exists. For | |
281 | example, the arguments to % must be integers. | |
282 | ||
283 | - We assume all subexpressions have a static, unchanging type. If | |
284 | we tried to support convenience variables, this would be a | |
285 | problem. | |
286 | ||
287 | - All values on the stack should always be fully zero- or | |
288 | sign-extended. | |
289 | ||
290 | (I wasn't sure whether to choose this or its opposite --- that | |
291 | only addresses are assumed extended --- but it turns out that | |
292 | neither convention completely eliminates spurious extend | |
293 | operations (if everything is always extended, then you have to | |
294 | extend after add, because it could overflow; if nothing is | |
295 | extended, then you end up producing extends whenever you change | |
296 | sizes), and this is simpler.) */ | |
297 | ||
298 | \f | |
299 | /* Generating bytecode from GDB expressions: the `trace' kludge */ | |
300 | ||
301 | /* The compiler in this file is a general-purpose mechanism for | |
302 | translating GDB expressions into bytecode. One ought to be able to | |
303 | find a million and one uses for it. | |
304 | ||
305 | However, at the moment it is HOPELESSLY BRAIN-DAMAGED for the sake | |
306 | of expediency. Let he who is without sin cast the first stone. | |
307 | ||
308 | For the data tracing facility, we need to insert `trace' bytecodes | |
309 | before each data fetch; this records all the memory that the | |
310 | expression touches in the course of evaluation, so that memory will | |
311 | be available when the user later tries to evaluate the expression | |
312 | in GDB. | |
313 | ||
314 | This should be done (I think) in a post-processing pass, that walks | |
315 | an arbitrary agent expression and inserts `trace' operations at the | |
316 | appropriate points. But it's much faster to just hack them | |
317 | directly into the code. And since we're in a crunch, that's what | |
318 | I've done. | |
319 | ||
320 | Setting the flag trace_kludge to non-zero enables the code that | |
321 | emits the trace bytecodes at the appropriate points. */ | |
322 | static int trace_kludge; | |
323 | ||
324 | /* Trace the lvalue on the stack, if it needs it. In either case, pop | |
325 | the value. Useful on the left side of a comma, and at the end of | |
326 | an expression being used for tracing. */ | |
327 | static void | |
328 | gen_traced_pop (ax, value) | |
329 | struct agent_expr *ax; | |
330 | struct axs_value *value; | |
331 | { | |
332 | if (trace_kludge) | |
333 | switch (value->kind) | |
334 | { | |
335 | case axs_rvalue: | |
336 | /* We don't trace rvalues, just the lvalues necessary to | |
337 | produce them. So just dispose of this value. */ | |
338 | ax_simple (ax, aop_pop); | |
339 | break; | |
340 | ||
341 | case axs_lvalue_memory: | |
342 | { | |
343 | int length = TYPE_LENGTH (value->type); | |
344 | ||
345 | /* There's no point in trying to use a trace_quick bytecode | |
346 | here, since "trace_quick SIZE pop" is three bytes, whereas | |
347 | "const8 SIZE trace" is also three bytes, does the same | |
348 | thing, and the simplest code which generates that will also | |
349 | work correctly for objects with large sizes. */ | |
350 | ax_const_l (ax, length); | |
351 | ax_simple (ax, aop_trace); | |
352 | } | |
353 | break; | |
354 | ||
355 | case axs_lvalue_register: | |
356 | /* We need to mention the register somewhere in the bytecode, | |
357 | so ax_reqs will pick it up and add it to the mask of | |
358 | registers used. */ | |
359 | ax_reg (ax, value->u.reg); | |
360 | ax_simple (ax, aop_pop); | |
361 | break; | |
362 | } | |
363 | else | |
364 | /* If we're not tracing, just pop the value. */ | |
365 | ax_simple (ax, aop_pop); | |
366 | } | |
367 | ||
368 | ||
369 | \f | |
370 | /* Generating bytecode from GDB expressions: helper functions */ | |
371 | ||
372 | /* Assume that the lower bits of the top of the stack is a value of | |
373 | type TYPE, and the upper bits are zero. Sign-extend if necessary. */ | |
374 | static void | |
375 | gen_sign_extend (ax, type) | |
376 | struct agent_expr *ax; | |
377 | struct type *type; | |
378 | { | |
379 | /* Do we need to sign-extend this? */ | |
380 | if (! TYPE_UNSIGNED (type)) | |
381 | ax_ext (ax, type->length * TARGET_CHAR_BIT); | |
382 | } | |
383 | ||
384 | ||
385 | /* Assume the lower bits of the top of the stack hold a value of type | |
386 | TYPE, and the upper bits are garbage. Sign-extend or truncate as | |
387 | needed. */ | |
388 | static void | |
389 | gen_extend (ax, type) | |
390 | struct agent_expr *ax; | |
391 | struct type *type; | |
392 | { | |
393 | int bits = type->length * TARGET_CHAR_BIT; | |
394 | /* I just had to. */ | |
395 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, bits)); | |
396 | } | |
397 | ||
398 | ||
399 | /* Assume that the top of the stack contains a value of type "pointer | |
400 | to TYPE"; generate code to fetch its value. Note that TYPE is the | |
401 | target type, not the pointer type. */ | |
402 | static void | |
403 | gen_fetch (ax, type) | |
404 | struct agent_expr *ax; | |
405 | struct type *type; | |
406 | { | |
407 | if (trace_kludge) | |
408 | { | |
409 | /* Record the area of memory we're about to fetch. */ | |
410 | ax_trace_quick (ax, TYPE_LENGTH (type)); | |
411 | } | |
412 | ||
413 | switch (type->code) | |
414 | { | |
415 | case TYPE_CODE_PTR: | |
416 | case TYPE_CODE_ENUM: | |
417 | case TYPE_CODE_INT: | |
418 | case TYPE_CODE_CHAR: | |
419 | /* It's a scalar value, so we know how to dereference it. How | |
420 | many bytes long is it? */ | |
421 | switch (type->length) | |
422 | { | |
423 | case 8 / TARGET_CHAR_BIT: ax_simple (ax, aop_ref8 ); break; | |
424 | case 16 / TARGET_CHAR_BIT: ax_simple (ax, aop_ref16); break; | |
425 | case 32 / TARGET_CHAR_BIT: ax_simple (ax, aop_ref32); break; | |
426 | case 64 / TARGET_CHAR_BIT: ax_simple (ax, aop_ref64); break; | |
427 | ||
428 | /* Either our caller shouldn't have asked us to dereference | |
429 | that pointer (other code's fault), or we're not | |
430 | implementing something we should be (this code's fault). | |
431 | In any case, it's a bug the user shouldn't see. */ | |
432 | default: | |
433 | error ("GDB bug: ax-gdb.c (gen_fetch): strange size"); | |
434 | } | |
435 | ||
436 | gen_sign_extend (ax, type); | |
437 | break; | |
438 | ||
439 | default: | |
440 | /* Either our caller shouldn't have asked us to dereference that | |
441 | pointer (other code's fault), or we're not implementing | |
442 | something we should be (this code's fault). In any case, | |
443 | it's a bug the user shouldn't see. */ | |
444 | error ("GDB bug: ax-gdb.c (gen_fetch): bad type code"); | |
445 | } | |
446 | } | |
447 | ||
448 | ||
449 | /* Generate code to left shift the top of the stack by DISTANCE bits, or | |
450 | right shift it by -DISTANCE bits if DISTANCE < 0. This generates | |
451 | unsigned (logical) right shifts. */ | |
452 | static void | |
453 | gen_left_shift (ax, distance) | |
454 | struct agent_expr *ax; | |
455 | int distance; | |
456 | { | |
457 | if (distance > 0) | |
458 | { | |
459 | ax_const_l (ax, distance); | |
460 | ax_simple (ax, aop_lsh); | |
461 | } | |
462 | else if (distance < 0) | |
463 | { | |
464 | ax_const_l (ax, -distance); | |
465 | ax_simple (ax, aop_rsh_unsigned); | |
466 | } | |
467 | } | |
468 | ||
469 | ||
470 | \f | |
471 | /* Generating bytecode from GDB expressions: symbol references */ | |
472 | ||
473 | /* Generate code to push the base address of the argument portion of | |
474 | the top stack frame. */ | |
475 | static void | |
476 | gen_frame_args_address (ax) | |
477 | struct agent_expr *ax; | |
478 | { | |
479 | long frame_reg, frame_offset; | |
480 | ||
481 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
482 | ax_reg (ax, frame_reg); | |
483 | gen_offset (ax, frame_offset); | |
484 | } | |
485 | ||
486 | ||
487 | /* Generate code to push the base address of the locals portion of the | |
488 | top stack frame. */ | |
489 | static void | |
490 | gen_frame_locals_address (ax) | |
491 | struct agent_expr *ax; | |
492 | { | |
493 | long frame_reg, frame_offset; | |
494 | ||
495 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
496 | ax_reg (ax, frame_reg); | |
497 | gen_offset (ax, frame_offset); | |
498 | } | |
499 | ||
500 | ||
501 | /* Generate code to add OFFSET to the top of the stack. Try to | |
502 | generate short and readable code. We use this for getting to | |
503 | variables on the stack, and structure members. If we were | |
504 | programming in ML, it would be clearer why these are the same | |
505 | thing. */ | |
506 | static void | |
507 | gen_offset (ax, offset) | |
508 | struct agent_expr *ax; | |
509 | int offset; | |
510 | { | |
511 | /* It would suffice to simply push the offset and add it, but this | |
512 | makes it easier to read positive and negative offsets in the | |
513 | bytecode. */ | |
514 | if (offset > 0) | |
515 | { | |
516 | ax_const_l (ax, offset); | |
517 | ax_simple (ax, aop_add); | |
518 | } | |
519 | else if (offset < 0) | |
520 | { | |
521 | ax_const_l (ax, -offset); | |
522 | ax_simple (ax, aop_sub); | |
523 | } | |
524 | } | |
525 | ||
526 | ||
527 | /* In many cases, a symbol's value is the offset from some other | |
528 | address (stack frame, base register, etc.) Generate code to add | |
529 | VAR's value to the top of the stack. */ | |
530 | static void | |
531 | gen_sym_offset (ax, var) | |
532 | struct agent_expr *ax; | |
533 | struct symbol *var; | |
534 | { | |
535 | gen_offset (ax, SYMBOL_VALUE (var)); | |
536 | } | |
537 | ||
538 | ||
539 | /* Generate code for a variable reference to AX. The variable is the | |
540 | symbol VAR. Set VALUE to describe the result. */ | |
541 | ||
542 | static void | |
543 | gen_var_ref (ax, value, var) | |
544 | struct agent_expr *ax; | |
545 | struct axs_value *value; | |
546 | struct symbol *var; | |
547 | { | |
548 | /* Dereference any typedefs. */ | |
549 | value->type = check_typedef (SYMBOL_TYPE (var)); | |
550 | ||
551 | /* I'm imitating the code in read_var_value. */ | |
552 | switch (SYMBOL_CLASS (var)) | |
553 | { | |
554 | case LOC_CONST: /* A constant, like an enum value. */ | |
555 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE (var)); | |
556 | value->kind = axs_rvalue; | |
557 | break; | |
558 | ||
559 | case LOC_LABEL: /* A goto label, being used as a value. */ | |
560 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE_ADDRESS (var)); | |
561 | value->kind = axs_rvalue; | |
562 | break; | |
563 | ||
564 | case LOC_CONST_BYTES: | |
565 | error ("GDB bug: ax-gdb.c (gen_var_ref): LOC_CONST_BYTES symbols are not supported"); | |
566 | ||
567 | /* Variable at a fixed location in memory. Easy. */ | |
568 | case LOC_STATIC: | |
569 | /* Push the address of the variable. */ | |
570 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (var)); | |
571 | value->kind = axs_lvalue_memory; | |
572 | break; | |
573 | ||
574 | case LOC_ARG: /* var lives in argument area of frame */ | |
575 | gen_frame_args_address (ax); | |
576 | gen_sym_offset (ax, var); | |
577 | value->kind = axs_lvalue_memory; | |
578 | break; | |
579 | ||
580 | case LOC_REF_ARG: /* As above, but the frame slot really | |
581 | holds the address of the variable. */ | |
582 | gen_frame_args_address (ax); | |
583 | gen_sym_offset (ax, var); | |
584 | /* Don't assume any particular pointer size. */ | |
585 | gen_fetch (ax, lookup_pointer_type (builtin_type_void)); | |
586 | value->kind = axs_lvalue_memory; | |
587 | break; | |
588 | ||
589 | case LOC_LOCAL: /* var lives in locals area of frame */ | |
590 | case LOC_LOCAL_ARG: | |
591 | gen_frame_locals_address (ax); | |
592 | gen_sym_offset (ax, var); | |
593 | value->kind = axs_lvalue_memory; | |
594 | break; | |
595 | ||
596 | case LOC_BASEREG: /* relative to some base register */ | |
597 | case LOC_BASEREG_ARG: | |
598 | ax_reg (ax, SYMBOL_BASEREG (var)); | |
599 | gen_sym_offset (ax, var); | |
600 | value->kind = axs_lvalue_memory; | |
601 | break; | |
602 | ||
603 | case LOC_TYPEDEF: | |
604 | error ("Cannot compute value of typedef `%s'.", | |
605 | SYMBOL_SOURCE_NAME (var)); | |
606 | break; | |
607 | ||
608 | case LOC_BLOCK: | |
609 | ax_const_l (ax, BLOCK_START (SYMBOL_BLOCK_VALUE (var))); | |
610 | value->kind = axs_rvalue; | |
611 | break; | |
612 | ||
613 | case LOC_REGISTER: | |
614 | case LOC_REGPARM: | |
615 | /* Don't generate any code at all; in the process of treating | |
616 | this as an lvalue or rvalue, the caller will generate the | |
617 | right code. */ | |
618 | value->kind = axs_lvalue_register; | |
619 | value->u.reg = SYMBOL_VALUE (var); | |
620 | break; | |
621 | ||
622 | /* A lot like LOC_REF_ARG, but the pointer lives directly in a | |
623 | register, not on the stack. Simpler than LOC_REGISTER and | |
624 | LOC_REGPARM, because it's just like any other case where the | |
625 | thing has a real address. */ | |
626 | case LOC_REGPARM_ADDR: | |
627 | ax_reg (ax, SYMBOL_VALUE (var)); | |
628 | value->kind = axs_lvalue_memory; | |
629 | break; | |
630 | ||
631 | case LOC_UNRESOLVED: | |
632 | { | |
633 | struct minimal_symbol *msym | |
634 | = lookup_minimal_symbol (SYMBOL_NAME (var), NULL, NULL); | |
635 | if (! msym) | |
636 | error ("Couldn't resolve symbol `%s'.", SYMBOL_SOURCE_NAME (var)); | |
637 | ||
638 | /* Push the address of the variable. */ | |
639 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (msym)); | |
640 | value->kind = axs_lvalue_memory; | |
641 | } | |
642 | break; | |
643 | ||
644 | case LOC_OPTIMIZED_OUT: | |
645 | error ("The variable `%s' has been optimized out.", | |
646 | SYMBOL_SOURCE_NAME (var)); | |
647 | break; | |
648 | ||
649 | default: | |
650 | error ("Cannot find value of botched symbol `%s'.", | |
651 | SYMBOL_SOURCE_NAME (var)); | |
652 | break; | |
653 | } | |
654 | } | |
655 | ||
656 | ||
657 | \f | |
658 | /* Generating bytecode from GDB expressions: literals */ | |
659 | ||
660 | static void | |
661 | gen_int_literal (ax, value, k, type) | |
662 | struct agent_expr *ax; | |
663 | struct axs_value *value; | |
664 | LONGEST k; | |
665 | struct type *type; | |
666 | { | |
667 | ax_const_l (ax, k); | |
668 | value->kind = axs_rvalue; | |
669 | value->type = type; | |
670 | } | |
671 | ||
672 | ||
673 | \f | |
674 | /* Generating bytecode from GDB expressions: unary conversions, casts */ | |
675 | ||
676 | /* Take what's on the top of the stack (as described by VALUE), and | |
677 | try to make an rvalue out of it. Signal an error if we can't do | |
678 | that. */ | |
679 | static void | |
680 | require_rvalue (ax, value) | |
681 | struct agent_expr *ax; | |
682 | struct axs_value *value; | |
683 | { | |
684 | switch (value->kind) | |
685 | { | |
686 | case axs_rvalue: | |
687 | /* It's already an rvalue. */ | |
688 | break; | |
689 | ||
690 | case axs_lvalue_memory: | |
691 | /* The top of stack is the address of the object. Dereference. */ | |
692 | gen_fetch (ax, value->type); | |
693 | break; | |
694 | ||
695 | case axs_lvalue_register: | |
696 | /* There's nothing on the stack, but value->u.reg is the | |
697 | register number containing the value. | |
698 | ||
699 | When we add floating-point support, this is going to have to | |
700 | change. What about SPARC register pairs, for example? */ | |
701 | ax_reg (ax, value->u.reg); | |
702 | gen_extend (ax, value->type); | |
703 | break; | |
704 | } | |
705 | ||
706 | value->kind = axs_rvalue; | |
707 | } | |
708 | ||
709 | ||
710 | /* Assume the top of the stack is described by VALUE, and perform the | |
711 | usual unary conversions. This is motivated by ANSI 6.2.2, but of | |
712 | course GDB expressions are not ANSI; they're the mishmash union of | |
713 | a bunch of languages. Rah. | |
714 | ||
715 | NOTE! This function promises to produce an rvalue only when the | |
716 | incoming value is of an appropriate type. In other words, the | |
717 | consumer of the value this function produces may assume the value | |
718 | is an rvalue only after checking its type. | |
719 | ||
720 | The immediate issue is that if the user tries to use a structure or | |
721 | union as an operand of, say, the `+' operator, we don't want to try | |
722 | to convert that structure to an rvalue; require_rvalue will bomb on | |
723 | structs and unions. Rather, we want to simply pass the struct | |
724 | lvalue through unchanged, and let `+' raise an error. */ | |
725 | ||
726 | static void | |
727 | gen_usual_unary (ax, value) | |
728 | struct agent_expr *ax; | |
729 | struct axs_value *value; | |
730 | { | |
731 | /* We don't have to generate any code for the usual integral | |
732 | conversions, since values are always represented as full-width on | |
733 | the stack. Should we tweak the type? */ | |
734 | ||
735 | /* Some types require special handling. */ | |
736 | switch (value->type->code) | |
737 | { | |
738 | /* Functions get converted to a pointer to the function. */ | |
739 | case TYPE_CODE_FUNC: | |
740 | value->type = lookup_pointer_type (value->type); | |
741 | value->kind = axs_rvalue; /* Should always be true, but just in case. */ | |
742 | break; | |
743 | ||
744 | /* Arrays get converted to a pointer to their first element, and | |
745 | are no longer an lvalue. */ | |
746 | case TYPE_CODE_ARRAY: | |
747 | { | |
748 | struct type *elements = TYPE_TARGET_TYPE (value->type); | |
749 | value->type = lookup_pointer_type (elements); | |
750 | value->kind = axs_rvalue; | |
751 | /* We don't need to generate any code; the address of the array | |
752 | is also the address of its first element. */ | |
753 | } | |
754 | break; | |
755 | ||
756 | /* Don't try to convert structures and unions to rvalues. Let the | |
757 | consumer signal an error. */ | |
758 | case TYPE_CODE_STRUCT: | |
759 | case TYPE_CODE_UNION: | |
760 | return; | |
761 | ||
762 | /* If the value is an enum, call it an integer. */ | |
763 | case TYPE_CODE_ENUM: | |
764 | value->type = builtin_type_int; | |
765 | break; | |
766 | } | |
767 | ||
768 | /* If the value is an lvalue, dereference it. */ | |
769 | require_rvalue (ax, value); | |
770 | } | |
771 | ||
772 | ||
773 | /* Return non-zero iff the type TYPE1 is considered "wider" than the | |
774 | type TYPE2, according to the rules described in gen_usual_arithmetic. */ | |
775 | static int | |
776 | type_wider_than (type1, type2) | |
777 | struct type *type1, *type2; | |
778 | { | |
779 | return (TYPE_LENGTH (type1) > TYPE_LENGTH (type2) | |
780 | || (TYPE_LENGTH (type1) == TYPE_LENGTH (type2) | |
781 | && TYPE_UNSIGNED (type1) | |
782 | && ! TYPE_UNSIGNED (type2))); | |
783 | } | |
784 | ||
785 | ||
786 | /* Return the "wider" of the two types TYPE1 and TYPE2. */ | |
787 | static struct type * | |
788 | max_type (type1, type2) | |
789 | struct type *type1, *type2; | |
790 | { | |
791 | return type_wider_than (type1, type2) ? type1 : type2; | |
792 | } | |
793 | ||
794 | ||
795 | /* Generate code to convert a scalar value of type FROM to type TO. */ | |
796 | static void | |
797 | gen_conversion (ax, from, to) | |
798 | struct agent_expr *ax; | |
799 | struct type *from, *to; | |
800 | { | |
801 | /* Perhaps there is a more graceful way to state these rules. */ | |
802 | ||
803 | /* If we're converting to a narrower type, then we need to clear out | |
804 | the upper bits. */ | |
805 | if (TYPE_LENGTH (to) < TYPE_LENGTH (from)) | |
806 | gen_extend (ax, from); | |
807 | ||
808 | /* If the two values have equal width, but different signednesses, | |
809 | then we need to extend. */ | |
810 | else if (TYPE_LENGTH (to) == TYPE_LENGTH (from)) | |
811 | { | |
812 | if (TYPE_UNSIGNED (from) != TYPE_UNSIGNED (to)) | |
813 | gen_extend (ax, to); | |
814 | } | |
815 | ||
816 | /* If we're converting to a wider type, and becoming unsigned, then | |
817 | we need to zero out any possible sign bits. */ | |
818 | else if (TYPE_LENGTH (to) > TYPE_LENGTH (from)) | |
819 | { | |
820 | if (TYPE_UNSIGNED (to)) | |
821 | gen_extend (ax, to); | |
822 | } | |
823 | } | |
824 | ||
825 | ||
826 | /* Return non-zero iff the type FROM will require any bytecodes to be | |
827 | emitted to be converted to the type TO. */ | |
828 | static int | |
829 | is_nontrivial_conversion (from, to) | |
830 | struct type *from, *to; | |
831 | { | |
832 | struct agent_expr *ax = new_agent_expr (0); | |
833 | int nontrivial; | |
834 | ||
835 | /* Actually generate the code, and see if anything came out. At the | |
836 | moment, it would be trivial to replicate the code in | |
837 | gen_conversion here, but in the future, when we're supporting | |
838 | floating point and the like, it may not be. Doing things this | |
839 | way allows this function to be independent of the logic in | |
840 | gen_conversion. */ | |
841 | gen_conversion (ax, from, to); | |
842 | nontrivial = ax->len > 0; | |
843 | free_agent_expr (ax); | |
844 | return nontrivial; | |
845 | } | |
846 | ||
847 | ||
848 | /* Generate code to perform the "usual arithmetic conversions" (ANSI C | |
849 | 6.2.1.5) for the two operands of an arithmetic operator. This | |
850 | effectively finds a "least upper bound" type for the two arguments, | |
851 | and promotes each argument to that type. *VALUE1 and *VALUE2 | |
852 | describe the values as they are passed in, and as they are left. */ | |
853 | static void | |
854 | gen_usual_arithmetic (ax, value1, value2) | |
855 | struct agent_expr *ax; | |
856 | struct axs_value *value1, *value2; | |
857 | { | |
858 | /* Do the usual binary conversions. */ | |
859 | if (TYPE_CODE (value1->type) == TYPE_CODE_INT | |
860 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
861 | { | |
862 | /* The ANSI integral promotions seem to work this way: Order the | |
863 | integer types by size, and then by signedness: an n-bit | |
864 | unsigned type is considered "wider" than an n-bit signed | |
865 | type. Promote to the "wider" of the two types, and always | |
866 | promote at least to int. */ | |
867 | struct type *target = max_type (builtin_type_int, | |
868 | max_type (value1->type, value2->type)); | |
869 | ||
870 | /* Deal with value2, on the top of the stack. */ | |
871 | gen_conversion (ax, value2->type, target); | |
872 | ||
873 | /* Deal with value1, not on the top of the stack. Don't | |
874 | generate the `swap' instructions if we're not actually going | |
875 | to do anything. */ | |
876 | if (is_nontrivial_conversion (value1->type, target)) | |
877 | { | |
878 | ax_simple (ax, aop_swap); | |
879 | gen_conversion (ax, value1->type, target); | |
880 | ax_simple (ax, aop_swap); | |
881 | } | |
882 | ||
883 | value1->type = value2->type = target; | |
884 | } | |
885 | } | |
886 | ||
887 | ||
888 | /* Generate code to perform the integral promotions (ANSI 6.2.1.1) on | |
889 | the value on the top of the stack, as described by VALUE. Assume | |
890 | the value has integral type. */ | |
891 | static void | |
892 | gen_integral_promotions (ax, value) | |
893 | struct agent_expr *ax; | |
894 | struct axs_value *value; | |
895 | { | |
896 | if (! type_wider_than (value->type, builtin_type_int)) | |
897 | { | |
898 | gen_conversion (ax, value->type, builtin_type_int); | |
899 | value->type = builtin_type_int; | |
900 | } | |
901 | else if (! type_wider_than (value->type, builtin_type_unsigned_int)) | |
902 | { | |
903 | gen_conversion (ax, value->type, builtin_type_unsigned_int); | |
904 | value->type = builtin_type_unsigned_int; | |
905 | } | |
906 | } | |
907 | ||
908 | ||
909 | /* Generate code for a cast to TYPE. */ | |
910 | static void | |
911 | gen_cast (ax, value, type) | |
912 | struct agent_expr *ax; | |
913 | struct axs_value *value; | |
914 | struct type *type; | |
915 | { | |
916 | /* GCC does allow casts to yield lvalues, so this should be fixed | |
917 | before merging these changes into the trunk. */ | |
918 | require_rvalue (ax, value); | |
919 | /* Dereference typedefs. */ | |
920 | type = check_typedef (type); | |
921 | ||
922 | switch (type->code) | |
923 | { | |
924 | case TYPE_CODE_PTR: | |
925 | /* It's implementation-defined, and I'll bet this is what GCC | |
926 | does. */ | |
927 | break; | |
928 | ||
929 | case TYPE_CODE_ARRAY: | |
930 | case TYPE_CODE_STRUCT: | |
931 | case TYPE_CODE_UNION: | |
932 | case TYPE_CODE_FUNC: | |
933 | error ("Illegal type cast: intended type must be scalar."); | |
934 | ||
935 | case TYPE_CODE_ENUM: | |
936 | /* We don't have to worry about the size of the value, because | |
937 | all our integral values are fully sign-extended, and when | |
938 | casting pointers we can do anything we like. Is there any | |
939 | way for us to actually know what GCC actually does with a | |
940 | cast like this? */ | |
941 | value->type = type; | |
942 | break; | |
943 | ||
944 | case TYPE_CODE_INT: | |
945 | gen_conversion (ax, value->type, type); | |
946 | break; | |
947 | ||
948 | case TYPE_CODE_VOID: | |
949 | /* We could pop the value, and rely on everyone else to check | |
950 | the type and notice that this value doesn't occupy a stack | |
951 | slot. But for now, leave the value on the stack, and | |
952 | preserve the "value == stack element" assumption. */ | |
953 | break; | |
954 | ||
955 | default: | |
956 | error ("Casts to requested type are not yet implemented."); | |
957 | } | |
958 | ||
959 | value->type = type; | |
960 | } | |
961 | ||
962 | ||
963 | \f | |
964 | /* Generating bytecode from GDB expressions: arithmetic */ | |
965 | ||
966 | /* Scale the integer on the top of the stack by the size of the target | |
967 | of the pointer type TYPE. */ | |
968 | static void | |
969 | gen_scale (ax, op, type) | |
970 | struct agent_expr *ax; | |
971 | enum agent_op op; | |
972 | struct type *type; | |
973 | { | |
974 | struct type *element = TYPE_TARGET_TYPE (type); | |
975 | ||
976 | if (element->length != 1) | |
977 | { | |
978 | ax_const_l (ax, element->length); | |
979 | ax_simple (ax, op); | |
980 | } | |
981 | } | |
982 | ||
983 | ||
984 | /* Generate code for an addition; non-trivial because we deal with | |
985 | pointer arithmetic. We set VALUE to describe the result value; we | |
986 | assume VALUE1 and VALUE2 describe the two operands, and that | |
987 | they've undergone the usual binary conversions. Used by both | |
988 | BINOP_ADD and BINOP_SUBSCRIPT. NAME is used in error messages. */ | |
989 | static void | |
990 | gen_add (ax, value, value1, value2, name) | |
991 | struct agent_expr *ax; | |
992 | struct axs_value *value, *value1, *value2; | |
993 | char *name; | |
994 | { | |
995 | /* Is it INT+PTR? */ | |
996 | if (value1->type->code == TYPE_CODE_INT | |
997 | && value2->type->code == TYPE_CODE_PTR) | |
998 | { | |
999 | /* Swap the values and proceed normally. */ | |
1000 | ax_simple (ax, aop_swap); | |
1001 | gen_scale (ax, aop_mul, value2->type); | |
1002 | ax_simple (ax, aop_add); | |
1003 | gen_extend (ax, value2->type); /* Catch overflow. */ | |
1004 | value->type = value2->type; | |
1005 | } | |
1006 | ||
1007 | /* Is it PTR+INT? */ | |
1008 | else if (value1->type->code == TYPE_CODE_PTR | |
1009 | && value2->type->code == TYPE_CODE_INT) | |
1010 | { | |
1011 | gen_scale (ax, aop_mul, value1->type); | |
1012 | ax_simple (ax, aop_add); | |
1013 | gen_extend (ax, value1->type); /* Catch overflow. */ | |
1014 | value->type = value1->type; | |
1015 | } | |
1016 | ||
1017 | /* Must be number + number; the usual binary conversions will have | |
1018 | brought them both to the same width. */ | |
1019 | else if (value1->type->code == TYPE_CODE_INT | |
1020 | && value2->type->code == TYPE_CODE_INT) | |
1021 | { | |
1022 | ax_simple (ax, aop_add); | |
1023 | gen_extend (ax, value1->type); /* Catch overflow. */ | |
1024 | value->type = value1->type; | |
1025 | } | |
1026 | ||
1027 | else | |
1028 | error ("Illegal combination of types in %s.", name); | |
1029 | ||
1030 | value->kind = axs_rvalue; | |
1031 | } | |
1032 | ||
1033 | ||
1034 | /* Generate code for an addition; non-trivial because we have to deal | |
1035 | with pointer arithmetic. We set VALUE to describe the result | |
1036 | value; we assume VALUE1 and VALUE2 describe the two operands, and | |
1037 | that they've undergone the usual binary conversions. */ | |
1038 | static void | |
1039 | gen_sub (ax, value, value1, value2) | |
1040 | struct agent_expr *ax; | |
1041 | struct axs_value *value, *value1, *value2; | |
1042 | { | |
1043 | struct type *element; | |
1044 | ||
1045 | if (value1->type->code == TYPE_CODE_PTR) | |
1046 | { | |
1047 | /* Is it PTR - INT? */ | |
1048 | if (value2->type->code == TYPE_CODE_INT) | |
1049 | { | |
1050 | gen_scale (ax, aop_mul, value1->type); | |
1051 | ax_simple (ax, aop_sub); | |
1052 | gen_extend (ax, value1->type); /* Catch overflow. */ | |
1053 | value->type = value1->type; | |
1054 | } | |
1055 | ||
1056 | /* Is it PTR - PTR? Strictly speaking, the types ought to | |
1057 | match, but this is what the normal GDB expression evaluator | |
1058 | tests for. */ | |
1059 | else if (value2->type->code == TYPE_CODE_PTR | |
1060 | && (TYPE_LENGTH (TYPE_TARGET_TYPE (value1->type)) | |
1061 | == TYPE_LENGTH (TYPE_TARGET_TYPE (value2->type)))) | |
1062 | { | |
1063 | ax_simple (ax, aop_sub); | |
1064 | gen_scale (ax, aop_div_unsigned, value1->type); | |
1065 | value->type = builtin_type_long; /* FIXME --- should be ptrdiff_t */ | |
1066 | } | |
1067 | else | |
1068 | error ("\ | |
1069 | First argument of `-' is a pointer, but second argument is neither\n\ | |
1070 | an integer nor a pointer of the same type."); | |
1071 | } | |
1072 | ||
1073 | /* Must be number + number. */ | |
1074 | else if (value1->type->code == TYPE_CODE_INT | |
1075 | && value2->type->code == TYPE_CODE_INT) | |
1076 | { | |
1077 | ax_simple (ax, aop_sub); | |
1078 | gen_extend (ax, value1->type); /* Catch overflow. */ | |
1079 | value->type = value1->type; | |
1080 | } | |
1081 | ||
1082 | else | |
1083 | error ("Illegal combination of types in subtraction."); | |
1084 | ||
1085 | value->kind = axs_rvalue; | |
1086 | } | |
1087 | ||
1088 | /* Generate code for a binary operator that doesn't do pointer magic. | |
1089 | We set VALUE to describe the result value; we assume VALUE1 and | |
1090 | VALUE2 describe the two operands, and that they've undergone the | |
1091 | usual binary conversions. MAY_CARRY should be non-zero iff the | |
1092 | result needs to be extended. NAME is the English name of the | |
1093 | operator, used in error messages */ | |
1094 | static void | |
1095 | gen_binop (ax, value, value1, value2, op, op_unsigned, may_carry, name) | |
1096 | struct agent_expr *ax; | |
1097 | struct axs_value *value, *value1, *value2; | |
1098 | enum agent_op op, op_unsigned; | |
1099 | int may_carry; | |
1100 | char *name; | |
1101 | { | |
1102 | /* We only handle INT op INT. */ | |
1103 | if ((value1->type->code != TYPE_CODE_INT) | |
1104 | || (value2->type->code != TYPE_CODE_INT)) | |
1105 | error ("Illegal combination of types in %s.", name); | |
1106 | ||
1107 | ax_simple (ax, | |
1108 | TYPE_UNSIGNED (value1->type) ? op_unsigned : op); | |
1109 | if (may_carry) | |
1110 | gen_extend (ax, value1->type); /* catch overflow */ | |
1111 | value->type = value1->type; | |
1112 | value->kind = axs_rvalue; | |
1113 | } | |
1114 | ||
1115 | ||
1116 | static void | |
1117 | gen_logical_not (ax, value) | |
1118 | struct agent_expr *ax; | |
1119 | struct axs_value *value; | |
1120 | { | |
1121 | if (TYPE_CODE (value->type) != TYPE_CODE_INT | |
1122 | && TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1123 | error ("Illegal type of operand to `!'."); | |
1124 | ||
1125 | gen_usual_unary (ax, value); | |
1126 | ax_simple (ax, aop_log_not); | |
1127 | value->type = builtin_type_int; | |
1128 | } | |
1129 | ||
1130 | ||
1131 | static void | |
1132 | gen_complement (ax, value) | |
1133 | struct agent_expr *ax; | |
1134 | struct axs_value *value; | |
1135 | { | |
1136 | if (TYPE_CODE (value->type) != TYPE_CODE_INT) | |
1137 | error ("Illegal type of operand to `~'."); | |
1138 | ||
1139 | gen_usual_unary (ax, value); | |
1140 | gen_integral_promotions (ax, value); | |
1141 | ax_simple (ax, aop_bit_not); | |
1142 | gen_extend (ax, value->type); | |
1143 | } | |
1144 | ||
1145 | ||
1146 | \f | |
1147 | /* Generating bytecode from GDB expressions: * & . -> @ sizeof */ | |
1148 | ||
1149 | /* Dereference the value on the top of the stack. */ | |
1150 | static void | |
1151 | gen_deref (ax, value) | |
1152 | struct agent_expr *ax; | |
1153 | struct axs_value *value; | |
1154 | { | |
1155 | /* The caller should check the type, because several operators use | |
1156 | this, and we don't know what error message to generate. */ | |
1157 | if (value->type->code != TYPE_CODE_PTR) | |
1158 | error ("GDB bug: ax-gdb.c (gen_deref): expected a pointer"); | |
1159 | ||
1160 | /* We've got an rvalue now, which is a pointer. We want to yield an | |
1161 | lvalue, whose address is exactly that pointer. So we don't | |
1162 | actually emit any code; we just change the type from "Pointer to | |
1163 | T" to "T", and mark the value as an lvalue in memory. Leave it | |
1164 | to the consumer to actually dereference it. */ | |
1165 | value->type = check_typedef (TYPE_TARGET_TYPE (value->type)); | |
1166 | value->kind = ((value->type->code == TYPE_CODE_FUNC) | |
1167 | ? axs_rvalue : axs_lvalue_memory); | |
1168 | } | |
1169 | ||
1170 | ||
1171 | /* Produce the address of the lvalue on the top of the stack. */ | |
1172 | static void | |
1173 | gen_address_of (ax, value) | |
1174 | struct agent_expr *ax; | |
1175 | struct axs_value *value; | |
1176 | { | |
1177 | /* Special case for taking the address of a function. The ANSI | |
1178 | standard describes this as a special case, too, so this | |
1179 | arrangement is not without motivation. */ | |
1180 | if (value->type->code == TYPE_CODE_FUNC) | |
1181 | /* The value's already an rvalue on the stack, so we just need to | |
1182 | change the type. */ | |
1183 | value->type = lookup_pointer_type (value->type); | |
1184 | else | |
1185 | switch (value->kind) | |
1186 | { | |
1187 | case axs_rvalue: | |
1188 | error ("Operand of `&' is an rvalue, which has no address."); | |
1189 | ||
1190 | case axs_lvalue_register: | |
1191 | error ("Operand of `&' is in a register, and has no address."); | |
1192 | ||
1193 | case axs_lvalue_memory: | |
1194 | value->kind = axs_rvalue; | |
1195 | value->type = lookup_pointer_type (value->type); | |
1196 | break; | |
1197 | } | |
1198 | } | |
1199 | ||
1200 | ||
1201 | /* A lot of this stuff will have to change to support C++. But we're | |
1202 | not going to deal with that at the moment. */ | |
1203 | ||
1204 | /* Find the field in the structure type TYPE named NAME, and return | |
1205 | its index in TYPE's field array. */ | |
1206 | static int | |
1207 | find_field (type, name) | |
1208 | struct type *type; | |
1209 | char *name; | |
1210 | { | |
1211 | int i; | |
1212 | ||
1213 | CHECK_TYPEDEF (type); | |
1214 | ||
1215 | /* Make sure this isn't C++. */ | |
1216 | if (TYPE_N_BASECLASSES (type) != 0) | |
1217 | error ("GDB bug: ax-gdb.c (find_field): derived classes supported"); | |
1218 | ||
1219 | for (i = 0; i < TYPE_NFIELDS (type); i++) | |
1220 | { | |
1221 | char *this_name = TYPE_FIELD_NAME (type, i); | |
1222 | ||
1223 | if (this_name && STREQ (name, this_name)) | |
1224 | return i; | |
1225 | ||
1226 | if (this_name[0] == '\0') | |
1227 | error ("GDB bug: ax-gdb.c (find_field): anonymous unions not supported"); | |
1228 | } | |
1229 | ||
1230 | error ("Couldn't find member named `%s' in struct/union `%s'", | |
1231 | name, type->tag_name); | |
1232 | ||
1233 | return 0; | |
1234 | } | |
1235 | ||
1236 | ||
1237 | /* Generate code to push the value of a bitfield of a structure whose | |
1238 | address is on the top of the stack. START and END give the | |
1239 | starting and one-past-ending *bit* numbers of the field within the | |
1240 | structure. */ | |
1241 | static void | |
1242 | gen_bitfield_ref (ax, value, type, start, end) | |
1243 | struct agent_expr *ax; | |
1244 | struct axs_value *value; | |
1245 | struct type *type; | |
1246 | int start, end; | |
1247 | { | |
1248 | /* Note that ops[i] fetches 8 << i bits. */ | |
1249 | static enum agent_op ops[] | |
1250 | = { aop_ref8, aop_ref16, aop_ref32, aop_ref64 }; | |
1251 | static int num_ops = (sizeof (ops) / sizeof (ops[0])); | |
1252 | ||
1253 | /* We don't want to touch any byte that the bitfield doesn't | |
1254 | actually occupy; we shouldn't make any accesses we're not | |
1255 | explicitly permitted to. We rely here on the fact that the | |
1256 | bytecode `ref' operators work on unaligned addresses. | |
1257 | ||
1258 | It takes some fancy footwork to get the stack to work the way | |
1259 | we'd like. Say we're retrieving a bitfield that requires three | |
1260 | fetches. Initially, the stack just contains the address: | |
1261 | addr | |
1262 | For the first fetch, we duplicate the address | |
1263 | addr addr | |
1264 | then add the byte offset, do the fetch, and shift and mask as | |
1265 | needed, yielding a fragment of the value, properly aligned for | |
1266 | the final bitwise or: | |
1267 | addr frag1 | |
1268 | then we swap, and repeat the process: | |
1269 | frag1 addr --- address on top | |
1270 | frag1 addr addr --- duplicate it | |
1271 | frag1 addr frag2 --- get second fragment | |
1272 | frag1 frag2 addr --- swap again | |
1273 | frag1 frag2 frag3 --- get third fragment | |
1274 | Notice that, since the third fragment is the last one, we don't | |
1275 | bother duplicating the address this time. Now we have all the | |
1276 | fragments on the stack, and we can simply `or' them together, | |
1277 | yielding the final value of the bitfield. */ | |
1278 | ||
1279 | /* The first and one-after-last bits in the field, but rounded down | |
1280 | and up to byte boundaries. */ | |
1281 | int bound_start = (start / TARGET_CHAR_BIT) * TARGET_CHAR_BIT; | |
1282 | int bound_end = (((end + TARGET_CHAR_BIT - 1) | |
1283 | / TARGET_CHAR_BIT) | |
1284 | * TARGET_CHAR_BIT); | |
1285 | ||
1286 | /* current bit offset within the structure */ | |
1287 | int offset; | |
1288 | ||
1289 | /* The index in ops of the opcode we're considering. */ | |
1290 | int op; | |
1291 | ||
1292 | /* The number of fragments we generated in the process. Probably | |
1293 | equal to the number of `one' bits in bytesize, but who cares? */ | |
1294 | int fragment_count; | |
1295 | ||
1296 | /* Dereference any typedefs. */ | |
1297 | type = check_typedef (type); | |
1298 | ||
1299 | /* Can we fetch the number of bits requested at all? */ | |
1300 | if ((end - start) > ((1 << num_ops) * 8)) | |
1301 | error ("GDB bug: ax-gdb.c (gen_bitfield_ref): bitfield too wide"); | |
1302 | ||
1303 | /* Note that we know here that we only need to try each opcode once. | |
1304 | That may not be true on machines with weird byte sizes. */ | |
1305 | offset = bound_start; | |
1306 | fragment_count = 0; | |
1307 | for (op = num_ops - 1; op >= 0; op--) | |
1308 | { | |
1309 | /* number of bits that ops[op] would fetch */ | |
1310 | int op_size = 8 << op; | |
1311 | ||
1312 | /* The stack at this point, from bottom to top, contains zero or | |
1313 | more fragments, then the address. */ | |
1314 | ||
1315 | /* Does this fetch fit within the bitfield? */ | |
1316 | if (offset + op_size <= bound_end) | |
1317 | { | |
1318 | /* Is this the last fragment? */ | |
1319 | int last_frag = (offset + op_size == bound_end); | |
1320 | ||
1321 | if (! last_frag) | |
1322 | ax_simple (ax, aop_dup); /* keep a copy of the address */ | |
1323 | ||
1324 | /* Add the offset. */ | |
1325 | gen_offset (ax, offset / TARGET_CHAR_BIT); | |
1326 | ||
1327 | if (trace_kludge) | |
1328 | { | |
1329 | /* Record the area of memory we're about to fetch. */ | |
1330 | ax_trace_quick (ax, op_size / TARGET_CHAR_BIT); | |
1331 | } | |
1332 | ||
1333 | /* Perform the fetch. */ | |
1334 | ax_simple (ax, ops[op]); | |
1335 | ||
1336 | /* Shift the bits we have to their proper position. | |
1337 | gen_left_shift will generate right shifts when the operand | |
1338 | is negative. | |
1339 | ||
1340 | A big-endian field diagram to ponder: | |
1341 | byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7 | |
1342 | +------++------++------++------++------++------++------++------+ | |
1343 | xxxxAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBCCCCCxxxxxxxxxxx | |
1344 | ^ ^ ^ ^ | |
1345 | bit number 16 32 48 53 | |
1346 | These are bit numbers as supplied by GDB. Note that the | |
1347 | bit numbers run from right to left once you've fetched the | |
1348 | value! | |
1349 | ||
1350 | A little-endian field diagram to ponder: | |
1351 | byte 7 byte 6 byte 5 byte 4 byte 3 byte 2 byte 1 byte 0 | |
1352 | +------++------++------++------++------++------++------++------+ | |
1353 | xxxxxxxxxxxAAAAABBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCCCCCCCCCCCCCxxxx | |
1354 | ^ ^ ^ ^ ^ | |
1355 | bit number 48 32 16 4 0 | |
1356 | ||
1357 | In both cases, the most significant end is on the left | |
1358 | (i.e. normal numeric writing order), which means that you | |
1359 | don't go crazy thinking about `left' and `right' shifts. | |
1360 | ||
1361 | We don't have to worry about masking yet: | |
1362 | - If they contain garbage off the least significant end, then we | |
1363 | must be looking at the low end of the field, and the right | |
1364 | shift will wipe them out. | |
1365 | - If they contain garbage off the most significant end, then we | |
1366 | must be looking at the most significant end of the word, and | |
1367 | the sign/zero extension will wipe them out. | |
1368 | - If we're in the interior of the word, then there is no garbage | |
1369 | on either end, because the ref operators zero-extend. */ | |
1370 | if (TARGET_BYTE_ORDER == BIG_ENDIAN) | |
1371 | gen_left_shift (ax, end - (offset + op_size)); | |
1372 | else | |
1373 | gen_left_shift (ax, offset - start); | |
1374 | ||
1375 | if (! last_frag) | |
1376 | /* Bring the copy of the address up to the top. */ | |
1377 | ax_simple (ax, aop_swap); | |
1378 | ||
1379 | offset += op_size; | |
1380 | fragment_count++; | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | /* Generate enough bitwise `or' operations to combine all the | |
1385 | fragments we left on the stack. */ | |
1386 | while (fragment_count-- > 1) | |
1387 | ax_simple (ax, aop_bit_or); | |
1388 | ||
1389 | /* Sign- or zero-extend the value as appropriate. */ | |
1390 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, end - start)); | |
1391 | ||
1392 | /* This is *not* an lvalue. Ugh. */ | |
1393 | value->kind = axs_rvalue; | |
1394 | value->type = type; | |
1395 | } | |
1396 | ||
1397 | ||
1398 | /* Generate code to reference the member named FIELD of a structure or | |
1399 | union. The top of the stack, as described by VALUE, should have | |
1400 | type (pointer to a)* struct/union. OPERATOR_NAME is the name of | |
1401 | the operator being compiled, and OPERAND_NAME is the kind of thing | |
1402 | it operates on; we use them in error messages. */ | |
1403 | static void | |
1404 | gen_struct_ref (ax, value, field, operator_name, operand_name) | |
1405 | struct agent_expr *ax; | |
1406 | struct axs_value *value; | |
1407 | char *field; | |
1408 | char *operator_name; | |
1409 | char *operand_name; | |
1410 | { | |
1411 | struct type *type; | |
1412 | int i; | |
1413 | ||
1414 | /* Follow pointers until we reach a non-pointer. These aren't the C | |
1415 | semantics, but they're what the normal GDB evaluator does, so we | |
1416 | should at least be consistent. */ | |
1417 | while (value->type->code == TYPE_CODE_PTR) | |
1418 | { | |
1419 | gen_usual_unary (ax, value); | |
1420 | gen_deref (ax, value); | |
1421 | } | |
1422 | type = value->type; | |
1423 | ||
1424 | /* This must yield a structure or a union. */ | |
1425 | if (TYPE_CODE (type) != TYPE_CODE_STRUCT | |
1426 | && TYPE_CODE (type) != TYPE_CODE_UNION) | |
1427 | error ("The left operand of `%s' is not a %s.", | |
1428 | operator_name, operand_name); | |
1429 | ||
1430 | /* And it must be in memory; we don't deal with structure rvalues, | |
1431 | or structures living in registers. */ | |
1432 | if (value->kind != axs_lvalue_memory) | |
1433 | error ("Structure does not live in memory."); | |
1434 | ||
1435 | i = find_field (type, field); | |
1436 | ||
1437 | /* Is this a bitfield? */ | |
1438 | if (TYPE_FIELD_PACKED (type, i)) | |
1439 | gen_bitfield_ref (ax, value, TYPE_FIELD_TYPE (type, i), | |
1440 | TYPE_FIELD_BITPOS (type, i), | |
1441 | (TYPE_FIELD_BITPOS (type, i) | |
1442 | + TYPE_FIELD_BITSIZE (type, i))); | |
1443 | else | |
1444 | { | |
1445 | gen_offset (ax, TYPE_FIELD_BITPOS (type, i) / TARGET_CHAR_BIT); | |
1446 | value->kind = axs_lvalue_memory; | |
1447 | value->type = TYPE_FIELD_TYPE (type, i); | |
1448 | } | |
1449 | } | |
1450 | ||
1451 | ||
1452 | /* Generate code for GDB's magical `repeat' operator. | |
1453 | LVALUE @ INT creates an array INT elements long, and whose elements | |
1454 | have the same type as LVALUE, located in memory so that LVALUE is | |
1455 | its first element. For example, argv[0]@argc gives you the array | |
1456 | of command-line arguments. | |
1457 | ||
1458 | Unfortunately, because we have to know the types before we actually | |
1459 | have a value for the expression, we can't implement this perfectly | |
1460 | without changing the type system, having values that occupy two | |
1461 | stack slots, doing weird things with sizeof, etc. So we require | |
1462 | the right operand to be a constant expression. */ | |
1463 | static void | |
1464 | gen_repeat (pc, ax, value) | |
1465 | union exp_element **pc; | |
1466 | struct agent_expr *ax; | |
1467 | struct axs_value *value; | |
1468 | { | |
1469 | struct axs_value value1; | |
1470 | /* We don't want to turn this into an rvalue, so no conversions | |
1471 | here. */ | |
1472 | gen_expr (pc, ax, &value1); | |
1473 | if (value1.kind != axs_lvalue_memory) | |
1474 | error ("Left operand of `@' must be an object in memory."); | |
1475 | ||
1476 | /* Evaluate the length; it had better be a constant. */ | |
1477 | { | |
1478 | struct value *v = const_expr (pc); | |
1479 | int length; | |
1480 | ||
1481 | if (! v) | |
1482 | error ("Right operand of `@' must be a constant, in agent expressions."); | |
1483 | if (v->type->code != TYPE_CODE_INT) | |
1484 | error ("Right operand of `@' must be an integer."); | |
1485 | length = value_as_long (v); | |
1486 | if (length <= 0) | |
1487 | error ("Right operand of `@' must be positive."); | |
1488 | ||
1489 | /* The top of the stack is already the address of the object, so | |
1490 | all we need to do is frob the type of the lvalue. */ | |
1491 | { | |
1492 | /* FIXME-type-allocation: need a way to free this type when we are | |
1493 | done with it. */ | |
1494 | struct type *range | |
1495 | = create_range_type (0, builtin_type_int, 0, length - 1); | |
1496 | struct type *array = create_array_type (0, value1.type, range); | |
1497 | ||
1498 | value->kind = axs_lvalue_memory; | |
1499 | value->type = array; | |
1500 | } | |
1501 | } | |
1502 | } | |
1503 | ||
1504 | ||
1505 | /* Emit code for the `sizeof' operator. | |
1506 | *PC should point at the start of the operand expression; we advance it | |
1507 | to the first instruction after the operand. */ | |
1508 | static void | |
1509 | gen_sizeof (pc, ax, value) | |
1510 | union exp_element **pc; | |
1511 | struct agent_expr *ax; | |
1512 | struct axs_value *value; | |
1513 | { | |
1514 | /* We don't care about the value of the operand expression; we only | |
1515 | care about its type. However, in the current arrangement, the | |
1516 | only way to find an expression's type is to generate code for it. | |
1517 | So we generate code for the operand, and then throw it away, | |
1518 | replacing it with code that simply pushes its size. */ | |
1519 | int start = ax->len; | |
1520 | gen_expr (pc, ax, value); | |
1521 | ||
1522 | /* Throw away the code we just generated. */ | |
1523 | ax->len = start; | |
1524 | ||
1525 | ax_const_l (ax, TYPE_LENGTH (value->type)); | |
1526 | value->kind = axs_rvalue; | |
1527 | value->type = builtin_type_int; | |
1528 | } | |
1529 | ||
1530 | \f | |
1531 | /* Generating bytecode from GDB expressions: general recursive thingy */ | |
1532 | ||
1533 | /* A gen_expr function written by a Gen-X'er guy. | |
1534 | Append code for the subexpression of EXPR starting at *POS_P to AX. */ | |
1535 | static void | |
1536 | gen_expr (pc, ax, value) | |
1537 | union exp_element **pc; | |
1538 | struct agent_expr *ax; | |
1539 | struct axs_value *value; | |
1540 | { | |
1541 | /* Used to hold the descriptions of operand expressions. */ | |
1542 | struct axs_value value1, value2; | |
1543 | enum exp_opcode op = (*pc)[0].opcode; | |
1544 | ||
1545 | /* If we're looking at a constant expression, just push its value. */ | |
1546 | { | |
1547 | struct value *v = maybe_const_expr (pc); | |
1548 | ||
1549 | if (v) | |
1550 | { | |
1551 | ax_const_l (ax, value_as_long (v)); | |
1552 | value->kind = axs_rvalue; | |
1553 | value->type = check_typedef (VALUE_TYPE (v)); | |
1554 | return; | |
1555 | } | |
1556 | } | |
1557 | ||
1558 | /* Otherwise, go ahead and generate code for it. */ | |
1559 | switch (op) | |
1560 | { | |
1561 | /* Binary arithmetic operators. */ | |
1562 | case BINOP_ADD: | |
1563 | case BINOP_SUB: | |
1564 | case BINOP_MUL: | |
1565 | case BINOP_DIV: | |
1566 | case BINOP_REM: | |
1567 | case BINOP_SUBSCRIPT: | |
1568 | case BINOP_BITWISE_AND: | |
1569 | case BINOP_BITWISE_IOR: | |
1570 | case BINOP_BITWISE_XOR: | |
1571 | (*pc)++; | |
1572 | gen_expr (pc, ax, &value1); | |
1573 | gen_usual_unary (ax, &value1); | |
1574 | gen_expr (pc, ax, &value2); | |
1575 | gen_usual_unary (ax, &value2); | |
1576 | gen_usual_arithmetic (ax, &value1, &value2); | |
1577 | switch (op) | |
1578 | { | |
1579 | case BINOP_ADD: | |
1580 | gen_add (ax, value, &value1, &value2, "addition"); | |
1581 | break; | |
1582 | case BINOP_SUB: | |
1583 | gen_sub (ax, value, &value1, &value2); | |
1584 | break; | |
1585 | case BINOP_MUL: | |
1586 | gen_binop (ax, value, &value1, &value2, | |
1587 | aop_mul, aop_mul, 1, "multiplication"); | |
1588 | break; | |
1589 | case BINOP_DIV: | |
1590 | gen_binop (ax, value, &value1, &value2, | |
1591 | aop_div_signed, aop_div_unsigned, 1, "division"); | |
1592 | break; | |
1593 | case BINOP_REM: | |
1594 | gen_binop (ax, value, &value1, &value2, | |
1595 | aop_rem_signed, aop_rem_unsigned, 1, "remainder"); | |
1596 | break; | |
1597 | case BINOP_SUBSCRIPT: | |
1598 | gen_add (ax, value, &value1, &value2, "array subscripting"); | |
1599 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1600 | error ("Illegal combination of types in array subscripting."); | |
1601 | gen_deref (ax, value); | |
1602 | break; | |
1603 | case BINOP_BITWISE_AND: | |
1604 | gen_binop (ax, value, &value1, &value2, | |
1605 | aop_bit_and, aop_bit_and, 0, "bitwise and"); | |
1606 | break; | |
1607 | ||
1608 | case BINOP_BITWISE_IOR: | |
1609 | gen_binop (ax, value, &value1, &value2, | |
1610 | aop_bit_or, aop_bit_or, 0, "bitwise or"); | |
1611 | break; | |
1612 | ||
1613 | case BINOP_BITWISE_XOR: | |
1614 | gen_binop (ax, value, &value1, &value2, | |
1615 | aop_bit_xor, aop_bit_xor, 0, "bitwise exclusive-or"); | |
1616 | break; | |
1617 | ||
1618 | default: | |
1619 | /* We should only list operators in the outer case statement | |
1620 | that we actually handle in the inner case statement. */ | |
1621 | error ("GDB bug: ax-gdb.c (gen_expr): op case sets don't match"); | |
1622 | } | |
1623 | break; | |
1624 | ||
1625 | /* Note that we need to be a little subtle about generating code | |
1626 | for comma. In C, we can do some optimizations here because | |
1627 | we know the left operand is only being evaluated for effect. | |
1628 | However, if the tracing kludge is in effect, then we always | |
1629 | need to evaluate the left hand side fully, so that all the | |
1630 | variables it mentions get traced. */ | |
1631 | case BINOP_COMMA: | |
1632 | (*pc)++; | |
1633 | gen_expr (pc, ax, &value1); | |
1634 | /* Don't just dispose of the left operand. We might be tracing, | |
1635 | in which case we want to emit code to trace it if it's an | |
1636 | lvalue. */ | |
1637 | gen_traced_pop (ax, &value1); | |
1638 | gen_expr (pc, ax, value); | |
1639 | /* It's the consumer's responsibility to trace the right operand. */ | |
1640 | break; | |
1641 | ||
1642 | case OP_LONG: /* some integer constant */ | |
1643 | { | |
1644 | struct type *type = (*pc)[1].type; | |
1645 | LONGEST k = (*pc)[2].longconst; | |
1646 | (*pc) += 4; | |
1647 | gen_int_literal (ax, value, k, type); | |
1648 | } | |
1649 | break; | |
1650 | ||
1651 | case OP_VAR_VALUE: | |
1652 | gen_var_ref (ax, value, (*pc)[2].symbol); | |
1653 | (*pc) += 4; | |
1654 | break; | |
1655 | ||
1656 | case OP_REGISTER: | |
1657 | { | |
1658 | int reg = (int) (*pc)[1].longconst; | |
1659 | (*pc) += 3; | |
1660 | value->kind = axs_lvalue_register; | |
1661 | value->u.reg = reg; | |
1662 | value->type = REGISTER_VIRTUAL_TYPE (reg); | |
1663 | } | |
1664 | break; | |
1665 | ||
1666 | case OP_INTERNALVAR: | |
1667 | error ("GDB agent expressions cannot use convenience variables."); | |
1668 | ||
1669 | /* Weirdo operator: see comments for gen_repeat for details. */ | |
1670 | case BINOP_REPEAT: | |
1671 | /* Note that gen_repeat handles its own argument evaluation. */ | |
1672 | (*pc)++; | |
1673 | gen_repeat (pc, ax, value); | |
1674 | break; | |
1675 | ||
1676 | case UNOP_CAST: | |
1677 | { | |
1678 | struct type *type = (*pc)[1].type; | |
1679 | (*pc) += 3; | |
1680 | gen_expr (pc, ax, value); | |
1681 | gen_cast (ax, value, type); | |
1682 | } | |
1683 | break; | |
1684 | ||
1685 | case UNOP_MEMVAL: | |
1686 | { | |
1687 | struct type *type = check_typedef ((*pc)[1].type); | |
1688 | (*pc) += 3; | |
1689 | gen_expr (pc, ax, value); | |
1690 | /* I'm not sure I understand UNOP_MEMVAL entirely. I think | |
1691 | it's just a hack for dealing with minsyms; you take some | |
1692 | integer constant, pretend it's the address of an lvalue of | |
1693 | the given type, and dereference it. */ | |
1694 | if (value->kind != axs_rvalue) | |
1695 | /* This would be weird. */ | |
1696 | error ("GDB bug: ax-gdb.c (gen_expr): OP_MEMVAL operand isn't an rvalue???"); | |
1697 | value->type = type; | |
1698 | value->kind = axs_lvalue_memory; | |
1699 | } | |
1700 | break; | |
1701 | ||
1702 | case UNOP_NEG: | |
1703 | (*pc)++; | |
1704 | /* -FOO is equivalent to 0 - FOO. */ | |
1705 | gen_int_literal (ax, &value1, (LONGEST) 0, builtin_type_int); | |
1706 | gen_usual_unary (ax, &value1); /* shouldn't do much */ | |
1707 | gen_expr (pc, ax, &value2); | |
1708 | gen_usual_unary (ax, &value2); | |
1709 | gen_usual_arithmetic (ax, &value1, &value2); | |
1710 | gen_sub (ax, value, &value1, &value2); | |
1711 | break; | |
1712 | ||
1713 | case UNOP_LOGICAL_NOT: | |
1714 | (*pc)++; | |
1715 | gen_expr (pc, ax, value); | |
1716 | gen_logical_not (ax, value); | |
1717 | break; | |
1718 | ||
1719 | case UNOP_COMPLEMENT: | |
1720 | (*pc)++; | |
1721 | gen_expr (pc, ax, value); | |
1722 | gen_complement (ax, value); | |
1723 | break; | |
1724 | ||
1725 | case UNOP_IND: | |
1726 | (*pc)++; | |
1727 | gen_expr (pc, ax, value); | |
1728 | gen_usual_unary (ax, value); | |
1729 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1730 | error ("Argument of unary `*' is not a pointer."); | |
1731 | gen_deref (ax, value); | |
1732 | break; | |
1733 | ||
1734 | case UNOP_ADDR: | |
1735 | (*pc)++; | |
1736 | gen_expr (pc, ax, value); | |
1737 | gen_address_of (ax, value); | |
1738 | break; | |
1739 | ||
1740 | case UNOP_SIZEOF: | |
1741 | (*pc)++; | |
1742 | /* Notice that gen_sizeof handles its own operand, unlike most | |
1743 | of the other unary operator functions. This is because we | |
1744 | have to throw away the code we generate. */ | |
1745 | gen_sizeof (pc, ax, value); | |
1746 | break; | |
1747 | ||
1748 | case STRUCTOP_STRUCT: | |
1749 | case STRUCTOP_PTR: | |
1750 | { | |
1751 | int length = (*pc)[1].longconst; | |
1752 | char *name = &(*pc)[2].string; | |
1753 | ||
1754 | (*pc) += 4 + BYTES_TO_EXP_ELEM (length + 1); | |
1755 | gen_expr (pc, ax, value); | |
1756 | if (op == STRUCTOP_STRUCT) | |
1757 | gen_struct_ref (ax, value, name, ".", "structure or union"); | |
1758 | else if (op == STRUCTOP_PTR) | |
1759 | gen_struct_ref (ax, value, name, "->", | |
1760 | "pointer to a structure or union"); | |
1761 | else | |
1762 | /* If this `if' chain doesn't handle it, then the case list | |
1763 | shouldn't mention it, and we shouldn't be here. */ | |
1764 | error ("GDB bug: ax-gdb.c (gen_expr): unhandled struct case"); | |
1765 | } | |
1766 | break; | |
1767 | ||
1768 | case OP_TYPE: | |
1769 | error ("Attempt to use a type name as an expression."); | |
1770 | ||
1771 | default: | |
1772 | error ("Unsupported operator in expression."); | |
1773 | } | |
1774 | } | |
1775 | ||
1776 | ||
1777 | \f | |
1778 | #if 0 /* not used */ | |
1779 | /* Generating bytecode from GDB expressions: driver */ | |
1780 | ||
1781 | /* Given a GDB expression EXPR, produce a string of agent bytecode | |
1782 | which computes its value. Return the agent expression, and set | |
1783 | *VALUE to describe its type, and whether it's an lvalue or rvalue. */ | |
1784 | struct agent_expr * | |
1785 | expr_to_agent (expr, value) | |
1786 | struct expression *expr; | |
1787 | struct axs_value *value; | |
1788 | { | |
1789 | struct cleanup *old_chain = 0; | |
1790 | struct agent_expr *ax = new_agent_expr (); | |
1791 | union exp_element *pc; | |
1792 | ||
1793 | old_chain = make_cleanup ((make_cleanup_func) free_agent_expr, ax); | |
1794 | ||
1795 | pc = expr->elts; | |
1796 | trace_kludge = 0; | |
1797 | gen_expr (&pc, ax, value); | |
1798 | ||
1799 | /* We have successfully built the agent expr, so cancel the cleanup | |
1800 | request. If we add more cleanups that we always want done, this | |
1801 | will have to get more complicated. */ | |
1802 | discard_cleanups (old_chain); | |
1803 | return ax; | |
1804 | } | |
1805 | ||
1806 | ||
1807 | /* Given a GDB expression EXPR denoting an lvalue in memory, produce a | |
1808 | string of agent bytecode which will leave its address and size on | |
1809 | the top of stack. Return the agent expression. | |
1810 | ||
1811 | Not sure this function is useful at all. */ | |
1812 | struct agent_expr * | |
1813 | expr_to_address_and_size (expr) | |
1814 | struct expression *expr; | |
1815 | { | |
1816 | struct axs_value value; | |
1817 | struct agent_expr *ax = expr_to_agent (expr, &value); | |
1818 | ||
1819 | /* Complain if the result is not a memory lvalue. */ | |
1820 | if (value.kind != axs_lvalue_memory) | |
1821 | { | |
1822 | free_agent_expr (ax); | |
1823 | error ("Expression does not denote an object in memory."); | |
1824 | } | |
1825 | ||
1826 | /* Push the object's size on the stack. */ | |
1827 | ax_const_l (ax, TYPE_LENGTH (value.type)); | |
1828 | ||
1829 | return ax; | |
1830 | } | |
1831 | #endif /* 0 */ | |
1832 | ||
1833 | /* Given a GDB expression EXPR, return bytecode to trace its value. | |
1834 | The result will use the `trace' and `trace_quick' bytecodes to | |
1835 | record the value of all memory touched by the expression. The | |
1836 | caller can then use the ax_reqs function to discover which | |
1837 | registers it relies upon. */ | |
1838 | struct agent_expr * | |
1839 | gen_trace_for_expr (scope, expr) | |
1840 | CORE_ADDR scope; | |
1841 | struct expression *expr; | |
1842 | { | |
1843 | struct cleanup *old_chain = 0; | |
1844 | struct agent_expr *ax = new_agent_expr (scope); | |
1845 | union exp_element *pc; | |
1846 | struct axs_value value; | |
1847 | ||
1848 | old_chain = make_cleanup ((make_cleanup_func) free_agent_expr, ax); | |
1849 | ||
1850 | pc = expr->elts; | |
1851 | trace_kludge = 1; | |
1852 | gen_expr (&pc, ax, &value); | |
1853 | ||
1854 | /* Make sure we record the final object, and get rid of it. */ | |
1855 | gen_traced_pop (ax, &value); | |
1856 | ||
1857 | /* Oh, and terminate. */ | |
1858 | ax_simple (ax, aop_end); | |
1859 | ||
1860 | /* We have successfully built the agent expr, so cancel the cleanup | |
1861 | request. If we add more cleanups that we always want done, this | |
1862 | will have to get more complicated. */ | |
1863 | discard_cleanups (old_chain); | |
1864 | return ax; | |
1865 | } | |
1866 | ||
1867 | ||
1868 | \f | |
1869 | /* The "agent" command, for testing: compile and disassemble an expression. */ | |
1870 | ||
1871 | static void | |
1872 | print_axs_value (f, value) | |
1873 | GDB_FILE *f; | |
1874 | struct axs_value *value; | |
1875 | { | |
1876 | switch (value->kind) | |
1877 | { | |
1878 | case axs_rvalue: | |
1879 | fputs_filtered ("rvalue", f); | |
1880 | break; | |
1881 | ||
1882 | case axs_lvalue_memory: | |
1883 | fputs_filtered ("memory lvalue", f); | |
1884 | break; | |
1885 | ||
1886 | case axs_lvalue_register: | |
1887 | fprintf_filtered (f, "register %d lvalue", value->u.reg); | |
1888 | break; | |
1889 | } | |
1890 | ||
1891 | fputs_filtered (" : ", f); | |
1892 | type_print (value->type, "", f, -1); | |
1893 | } | |
1894 | ||
1895 | ||
1896 | static void | |
1897 | agent_command (exp, from_tty) | |
1898 | char *exp; | |
1899 | int from_tty; | |
1900 | { | |
1901 | struct cleanup *old_chain = 0; | |
1902 | struct expression *expr; | |
1903 | struct agent_expr *agent; | |
1904 | struct agent_reqs reqs; | |
1905 | struct frame_info *fi = get_current_frame (); /* need current scope */ | |
1906 | ||
1907 | /* We don't deal with overlay debugging at the moment. We need to | |
1908 | think more carefully about this. If you copy this code into | |
1909 | another command, change the error message; the user shouldn't | |
1910 | have to know anything about agent expressions. */ | |
1911 | if (overlay_debugging) | |
1912 | error ("GDB can't do agent expression translation with overlays."); | |
1913 | ||
1914 | if (exp == 0) | |
1915 | error_no_arg ("expression to translate"); | |
1916 | ||
1917 | expr = parse_expression (exp); | |
1918 | old_chain = make_cleanup ((make_cleanup_func) free_current_contents, &expr); | |
1919 | agent = gen_trace_for_expr (fi->pc, expr); | |
1920 | make_cleanup ((make_cleanup_func) free_agent_expr, agent); | |
1921 | ax_print (gdb_stdout, agent); | |
1922 | ax_reqs (agent, &reqs); | |
1923 | ||
1924 | do_cleanups (old_chain); | |
1925 | dont_repeat (); | |
1926 | } | |
1927 | ||
1928 | \f | |
1929 | /* Initialization code. */ | |
1930 | ||
1931 | void _initialize_ax_gdb PARAMS ((void)); | |
1932 | void | |
1933 | _initialize_ax_gdb () | |
1934 | { | |
1935 | struct cmd_list_element *c; | |
1936 | ||
1937 | add_cmd ("agent", class_maintenance, agent_command, | |
1938 | "Translate an expression into remote agent bytecode.", | |
1939 | &maintenancelist); | |
1940 | } |