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c906108c | 1 | /* GDB-specific functions for operating on agent expressions |
d9fcf2fb | 2 | Copyright 1998, 2000 Free Software Foundation, Inc. |
c906108c | 3 | |
c5aa993b | 4 | This file is part of GDB. |
c906108c | 5 | |
c5aa993b JM |
6 | This program is free software; you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
c906108c | 10 | |
c5aa993b JM |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
c906108c | 15 | |
c5aa993b JM |
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, | |
19 | Boston, MA 02111-1307, USA. */ | |
c906108c | 20 | |
c906108c SS |
21 | #include "defs.h" |
22 | #include "symtab.h" | |
23 | #include "symfile.h" | |
24 | #include "gdbtypes.h" | |
25 | #include "value.h" | |
26 | #include "expression.h" | |
27 | #include "command.h" | |
28 | #include "gdbcmd.h" | |
29 | #include "frame.h" | |
30 | #include "target.h" | |
31 | #include "ax.h" | |
32 | #include "ax-gdb.h" | |
33 | ||
6426a772 JM |
34 | /* To make sense of this file, you should read doc/agentexpr.texi. |
35 | Then look at the types and enums in ax-gdb.h. For the code itself, | |
36 | look at gen_expr, towards the bottom; that's the main function that | |
37 | looks at the GDB expressions and calls everything else to generate | |
38 | code. | |
c906108c SS |
39 | |
40 | I'm beginning to wonder whether it wouldn't be nicer to internally | |
41 | generate trees, with types, and then spit out the bytecode in | |
42 | linear form afterwards; we could generate fewer `swap', `ext', and | |
43 | `zero_ext' bytecodes that way; it would make good constant folding | |
44 | easier, too. But at the moment, I think we should be willing to | |
45 | pay for the simplicity of this code with less-than-optimal bytecode | |
46 | strings. | |
47 | ||
c5aa993b JM |
48 | Remember, "GBD" stands for "Great Britain, Dammit!" So be careful. */ |
49 | \f | |
c906108c SS |
50 | |
51 | ||
c906108c SS |
52 | /* Prototypes for local functions. */ |
53 | ||
54 | /* There's a standard order to the arguments of these functions: | |
55 | union exp_element ** --- pointer into expression | |
56 | struct agent_expr * --- agent expression buffer to generate code into | |
57 | struct axs_value * --- describes value left on top of stack */ | |
c5aa993b | 58 | |
a14ed312 KB |
59 | static struct value *const_var_ref (struct symbol *var); |
60 | static struct value *const_expr (union exp_element **pc); | |
61 | static struct value *maybe_const_expr (union exp_element **pc); | |
62 | ||
63 | static void gen_traced_pop (struct agent_expr *, struct axs_value *); | |
64 | ||
65 | static void gen_sign_extend (struct agent_expr *, struct type *); | |
66 | static void gen_extend (struct agent_expr *, struct type *); | |
67 | static void gen_fetch (struct agent_expr *, struct type *); | |
68 | static void gen_left_shift (struct agent_expr *, int); | |
69 | ||
70 | ||
71 | static void gen_frame_args_address (struct agent_expr *); | |
72 | static void gen_frame_locals_address (struct agent_expr *); | |
73 | static void gen_offset (struct agent_expr *ax, int offset); | |
74 | static void gen_sym_offset (struct agent_expr *, struct symbol *); | |
75 | static void gen_var_ref (struct agent_expr *ax, | |
76 | struct axs_value *value, struct symbol *var); | |
77 | ||
78 | ||
79 | static void gen_int_literal (struct agent_expr *ax, | |
80 | struct axs_value *value, | |
81 | LONGEST k, struct type *type); | |
82 | ||
83 | ||
84 | static void require_rvalue (struct agent_expr *ax, struct axs_value *value); | |
85 | static void gen_usual_unary (struct agent_expr *ax, struct axs_value *value); | |
86 | static int type_wider_than (struct type *type1, struct type *type2); | |
87 | static struct type *max_type (struct type *type1, struct type *type2); | |
88 | static void gen_conversion (struct agent_expr *ax, | |
89 | struct type *from, struct type *to); | |
90 | static int is_nontrivial_conversion (struct type *from, struct type *to); | |
91 | static void gen_usual_arithmetic (struct agent_expr *ax, | |
92 | struct axs_value *value1, | |
93 | struct axs_value *value2); | |
94 | static void gen_integral_promotions (struct agent_expr *ax, | |
95 | struct axs_value *value); | |
96 | static void gen_cast (struct agent_expr *ax, | |
97 | struct axs_value *value, struct type *type); | |
98 | static void gen_scale (struct agent_expr *ax, | |
99 | enum agent_op op, struct type *type); | |
100 | static void gen_add (struct agent_expr *ax, | |
101 | struct axs_value *value, | |
102 | struct axs_value *value1, | |
103 | struct axs_value *value2, char *name); | |
104 | static void gen_sub (struct agent_expr *ax, | |
105 | struct axs_value *value, | |
106 | struct axs_value *value1, struct axs_value *value2); | |
107 | static void gen_binop (struct agent_expr *ax, | |
108 | struct axs_value *value, | |
109 | struct axs_value *value1, | |
110 | struct axs_value *value2, | |
111 | enum agent_op op, | |
112 | enum agent_op op_unsigned, int may_carry, char *name); | |
113 | static void gen_logical_not (struct agent_expr *ax, struct axs_value *value); | |
114 | static void gen_complement (struct agent_expr *ax, struct axs_value *value); | |
115 | static void gen_deref (struct agent_expr *, struct axs_value *); | |
116 | static void gen_address_of (struct agent_expr *, struct axs_value *); | |
117 | static int find_field (struct type *type, char *name); | |
118 | static void gen_bitfield_ref (struct agent_expr *ax, | |
119 | struct axs_value *value, | |
120 | struct type *type, int start, int end); | |
121 | static void gen_struct_ref (struct agent_expr *ax, | |
122 | struct axs_value *value, | |
123 | char *field, | |
124 | char *operator_name, char *operand_name); | |
125 | static void gen_repeat (union exp_element **pc, | |
126 | struct agent_expr *ax, struct axs_value *value); | |
127 | static void gen_sizeof (union exp_element **pc, | |
128 | struct agent_expr *ax, struct axs_value *value); | |
129 | static void gen_expr (union exp_element **pc, | |
130 | struct agent_expr *ax, struct axs_value *value); | |
c5aa993b | 131 | |
d9fcf2fb | 132 | static void print_axs_value (struct ui_file *f, struct axs_value * value); |
a14ed312 | 133 | static void agent_command (char *exp, int from_tty); |
c906108c | 134 | \f |
c5aa993b | 135 | |
c906108c SS |
136 | /* Detecting constant expressions. */ |
137 | ||
138 | /* If the variable reference at *PC is a constant, return its value. | |
139 | Otherwise, return zero. | |
140 | ||
141 | Hey, Wally! How can a variable reference be a constant? | |
142 | ||
143 | Well, Beav, this function really handles the OP_VAR_VALUE operator, | |
144 | not specifically variable references. GDB uses OP_VAR_VALUE to | |
145 | refer to any kind of symbolic reference: function names, enum | |
146 | elements, and goto labels are all handled through the OP_VAR_VALUE | |
147 | operator, even though they're constants. It makes sense given the | |
148 | situation. | |
149 | ||
150 | Gee, Wally, don'cha wonder sometimes if data representations that | |
151 | subvert commonly accepted definitions of terms in favor of heavily | |
152 | context-specific interpretations are really just a tool of the | |
153 | programming hegemony to preserve their power and exclude the | |
154 | proletariat? */ | |
155 | ||
156 | static struct value * | |
157 | const_var_ref (var) | |
158 | struct symbol *var; | |
159 | { | |
160 | struct type *type = SYMBOL_TYPE (var); | |
161 | ||
162 | switch (SYMBOL_CLASS (var)) | |
163 | { | |
164 | case LOC_CONST: | |
165 | return value_from_longest (type, (LONGEST) SYMBOL_VALUE (var)); | |
166 | ||
167 | case LOC_LABEL: | |
4478b372 | 168 | return value_from_pointer (type, (CORE_ADDR) SYMBOL_VALUE_ADDRESS (var)); |
c906108c SS |
169 | |
170 | default: | |
171 | return 0; | |
172 | } | |
173 | } | |
174 | ||
175 | ||
176 | /* If the expression starting at *PC has a constant value, return it. | |
177 | Otherwise, return zero. If we return a value, then *PC will be | |
178 | advanced to the end of it. If we return zero, *PC could be | |
179 | anywhere. */ | |
180 | static struct value * | |
181 | const_expr (pc) | |
182 | union exp_element **pc; | |
183 | { | |
184 | enum exp_opcode op = (*pc)->opcode; | |
185 | struct value *v1; | |
186 | ||
187 | switch (op) | |
188 | { | |
189 | case OP_LONG: | |
190 | { | |
191 | struct type *type = (*pc)[1].type; | |
192 | LONGEST k = (*pc)[2].longconst; | |
193 | (*pc) += 4; | |
194 | return value_from_longest (type, k); | |
195 | } | |
196 | ||
197 | case OP_VAR_VALUE: | |
198 | { | |
199 | struct value *v = const_var_ref ((*pc)[2].symbol); | |
200 | (*pc) += 4; | |
201 | return v; | |
202 | } | |
203 | ||
c5aa993b | 204 | /* We could add more operators in here. */ |
c906108c SS |
205 | |
206 | case UNOP_NEG: | |
207 | (*pc)++; | |
208 | v1 = const_expr (pc); | |
209 | if (v1) | |
210 | return value_neg (v1); | |
211 | else | |
212 | return 0; | |
213 | ||
214 | default: | |
215 | return 0; | |
216 | } | |
217 | } | |
218 | ||
219 | ||
220 | /* Like const_expr, but guarantee also that *PC is undisturbed if the | |
221 | expression is not constant. */ | |
222 | static struct value * | |
223 | maybe_const_expr (pc) | |
224 | union exp_element **pc; | |
225 | { | |
226 | union exp_element *tentative_pc = *pc; | |
227 | struct value *v = const_expr (&tentative_pc); | |
228 | ||
229 | /* If we got a value, then update the real PC. */ | |
230 | if (v) | |
231 | *pc = tentative_pc; | |
c5aa993b | 232 | |
c906108c SS |
233 | return v; |
234 | } | |
c906108c | 235 | \f |
c5aa993b | 236 | |
c906108c SS |
237 | /* Generating bytecode from GDB expressions: general assumptions */ |
238 | ||
239 | /* Here are a few general assumptions made throughout the code; if you | |
240 | want to make a change that contradicts one of these, then you'd | |
241 | better scan things pretty thoroughly. | |
242 | ||
243 | - We assume that all values occupy one stack element. For example, | |
c5aa993b JM |
244 | sometimes we'll swap to get at the left argument to a binary |
245 | operator. If we decide that void values should occupy no stack | |
246 | elements, or that synthetic arrays (whose size is determined at | |
247 | run time, created by the `@' operator) should occupy two stack | |
248 | elements (address and length), then this will cause trouble. | |
c906108c SS |
249 | |
250 | - We assume the stack elements are infinitely wide, and that we | |
c5aa993b JM |
251 | don't have to worry what happens if the user requests an |
252 | operation that is wider than the actual interpreter's stack. | |
253 | That is, it's up to the interpreter to handle directly all the | |
254 | integer widths the user has access to. (Woe betide the language | |
255 | with bignums!) | |
c906108c SS |
256 | |
257 | - We don't support side effects. Thus, we don't have to worry about | |
c5aa993b | 258 | GCC's generalized lvalues, function calls, etc. |
c906108c SS |
259 | |
260 | - We don't support floating point. Many places where we switch on | |
c5aa993b JM |
261 | some type don't bother to include cases for floating point; there |
262 | may be even more subtle ways this assumption exists. For | |
263 | example, the arguments to % must be integers. | |
c906108c SS |
264 | |
265 | - We assume all subexpressions have a static, unchanging type. If | |
c5aa993b JM |
266 | we tried to support convenience variables, this would be a |
267 | problem. | |
c906108c SS |
268 | |
269 | - All values on the stack should always be fully zero- or | |
c5aa993b JM |
270 | sign-extended. |
271 | ||
272 | (I wasn't sure whether to choose this or its opposite --- that | |
273 | only addresses are assumed extended --- but it turns out that | |
274 | neither convention completely eliminates spurious extend | |
275 | operations (if everything is always extended, then you have to | |
276 | extend after add, because it could overflow; if nothing is | |
277 | extended, then you end up producing extends whenever you change | |
278 | sizes), and this is simpler.) */ | |
c906108c | 279 | \f |
c5aa993b | 280 | |
c906108c SS |
281 | /* Generating bytecode from GDB expressions: the `trace' kludge */ |
282 | ||
283 | /* The compiler in this file is a general-purpose mechanism for | |
284 | translating GDB expressions into bytecode. One ought to be able to | |
285 | find a million and one uses for it. | |
286 | ||
287 | However, at the moment it is HOPELESSLY BRAIN-DAMAGED for the sake | |
288 | of expediency. Let he who is without sin cast the first stone. | |
289 | ||
290 | For the data tracing facility, we need to insert `trace' bytecodes | |
291 | before each data fetch; this records all the memory that the | |
292 | expression touches in the course of evaluation, so that memory will | |
293 | be available when the user later tries to evaluate the expression | |
294 | in GDB. | |
295 | ||
296 | This should be done (I think) in a post-processing pass, that walks | |
297 | an arbitrary agent expression and inserts `trace' operations at the | |
298 | appropriate points. But it's much faster to just hack them | |
299 | directly into the code. And since we're in a crunch, that's what | |
300 | I've done. | |
301 | ||
302 | Setting the flag trace_kludge to non-zero enables the code that | |
303 | emits the trace bytecodes at the appropriate points. */ | |
304 | static int trace_kludge; | |
305 | ||
306 | /* Trace the lvalue on the stack, if it needs it. In either case, pop | |
307 | the value. Useful on the left side of a comma, and at the end of | |
308 | an expression being used for tracing. */ | |
309 | static void | |
310 | gen_traced_pop (ax, value) | |
311 | struct agent_expr *ax; | |
312 | struct axs_value *value; | |
313 | { | |
314 | if (trace_kludge) | |
315 | switch (value->kind) | |
316 | { | |
317 | case axs_rvalue: | |
318 | /* We don't trace rvalues, just the lvalues necessary to | |
c5aa993b | 319 | produce them. So just dispose of this value. */ |
c906108c SS |
320 | ax_simple (ax, aop_pop); |
321 | break; | |
322 | ||
323 | case axs_lvalue_memory: | |
324 | { | |
325 | int length = TYPE_LENGTH (value->type); | |
326 | ||
327 | /* There's no point in trying to use a trace_quick bytecode | |
328 | here, since "trace_quick SIZE pop" is three bytes, whereas | |
329 | "const8 SIZE trace" is also three bytes, does the same | |
330 | thing, and the simplest code which generates that will also | |
331 | work correctly for objects with large sizes. */ | |
332 | ax_const_l (ax, length); | |
333 | ax_simple (ax, aop_trace); | |
334 | } | |
c5aa993b | 335 | break; |
c906108c SS |
336 | |
337 | case axs_lvalue_register: | |
338 | /* We need to mention the register somewhere in the bytecode, | |
339 | so ax_reqs will pick it up and add it to the mask of | |
340 | registers used. */ | |
341 | ax_reg (ax, value->u.reg); | |
342 | ax_simple (ax, aop_pop); | |
343 | break; | |
344 | } | |
345 | else | |
346 | /* If we're not tracing, just pop the value. */ | |
347 | ax_simple (ax, aop_pop); | |
348 | } | |
c5aa993b | 349 | \f |
c906108c SS |
350 | |
351 | ||
c906108c SS |
352 | /* Generating bytecode from GDB expressions: helper functions */ |
353 | ||
354 | /* Assume that the lower bits of the top of the stack is a value of | |
355 | type TYPE, and the upper bits are zero. Sign-extend if necessary. */ | |
356 | static void | |
357 | gen_sign_extend (ax, type) | |
358 | struct agent_expr *ax; | |
359 | struct type *type; | |
360 | { | |
361 | /* Do we need to sign-extend this? */ | |
c5aa993b | 362 | if (!TYPE_UNSIGNED (type)) |
c906108c SS |
363 | ax_ext (ax, type->length * TARGET_CHAR_BIT); |
364 | } | |
365 | ||
366 | ||
367 | /* Assume the lower bits of the top of the stack hold a value of type | |
368 | TYPE, and the upper bits are garbage. Sign-extend or truncate as | |
369 | needed. */ | |
370 | static void | |
371 | gen_extend (ax, type) | |
372 | struct agent_expr *ax; | |
373 | struct type *type; | |
374 | { | |
375 | int bits = type->length * TARGET_CHAR_BIT; | |
376 | /* I just had to. */ | |
377 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, bits)); | |
378 | } | |
379 | ||
380 | ||
381 | /* Assume that the top of the stack contains a value of type "pointer | |
382 | to TYPE"; generate code to fetch its value. Note that TYPE is the | |
383 | target type, not the pointer type. */ | |
384 | static void | |
385 | gen_fetch (ax, type) | |
386 | struct agent_expr *ax; | |
387 | struct type *type; | |
388 | { | |
389 | if (trace_kludge) | |
390 | { | |
391 | /* Record the area of memory we're about to fetch. */ | |
392 | ax_trace_quick (ax, TYPE_LENGTH (type)); | |
393 | } | |
394 | ||
395 | switch (type->code) | |
396 | { | |
397 | case TYPE_CODE_PTR: | |
398 | case TYPE_CODE_ENUM: | |
399 | case TYPE_CODE_INT: | |
400 | case TYPE_CODE_CHAR: | |
401 | /* It's a scalar value, so we know how to dereference it. How | |
402 | many bytes long is it? */ | |
403 | switch (type->length) | |
404 | { | |
c5aa993b JM |
405 | case 8 / TARGET_CHAR_BIT: |
406 | ax_simple (ax, aop_ref8); | |
407 | break; | |
408 | case 16 / TARGET_CHAR_BIT: | |
409 | ax_simple (ax, aop_ref16); | |
410 | break; | |
411 | case 32 / TARGET_CHAR_BIT: | |
412 | ax_simple (ax, aop_ref32); | |
413 | break; | |
414 | case 64 / TARGET_CHAR_BIT: | |
415 | ax_simple (ax, aop_ref64); | |
416 | break; | |
c906108c SS |
417 | |
418 | /* Either our caller shouldn't have asked us to dereference | |
419 | that pointer (other code's fault), or we're not | |
420 | implementing something we should be (this code's fault). | |
421 | In any case, it's a bug the user shouldn't see. */ | |
422 | default: | |
6426a772 | 423 | internal_error ("ax-gdb.c (gen_fetch): strange size"); |
c906108c SS |
424 | } |
425 | ||
426 | gen_sign_extend (ax, type); | |
427 | break; | |
428 | ||
429 | default: | |
430 | /* Either our caller shouldn't have asked us to dereference that | |
c5aa993b JM |
431 | pointer (other code's fault), or we're not implementing |
432 | something we should be (this code's fault). In any case, | |
433 | it's a bug the user shouldn't see. */ | |
6426a772 | 434 | internal_error ("ax-gdb.c (gen_fetch): bad type code"); |
c906108c SS |
435 | } |
436 | } | |
437 | ||
438 | ||
439 | /* Generate code to left shift the top of the stack by DISTANCE bits, or | |
440 | right shift it by -DISTANCE bits if DISTANCE < 0. This generates | |
441 | unsigned (logical) right shifts. */ | |
442 | static void | |
443 | gen_left_shift (ax, distance) | |
444 | struct agent_expr *ax; | |
445 | int distance; | |
446 | { | |
447 | if (distance > 0) | |
448 | { | |
449 | ax_const_l (ax, distance); | |
450 | ax_simple (ax, aop_lsh); | |
451 | } | |
452 | else if (distance < 0) | |
453 | { | |
454 | ax_const_l (ax, -distance); | |
455 | ax_simple (ax, aop_rsh_unsigned); | |
456 | } | |
457 | } | |
c5aa993b | 458 | \f |
c906108c SS |
459 | |
460 | ||
c906108c SS |
461 | /* Generating bytecode from GDB expressions: symbol references */ |
462 | ||
463 | /* Generate code to push the base address of the argument portion of | |
464 | the top stack frame. */ | |
465 | static void | |
466 | gen_frame_args_address (ax) | |
467 | struct agent_expr *ax; | |
468 | { | |
469 | long frame_reg, frame_offset; | |
470 | ||
471 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
c5aa993b | 472 | ax_reg (ax, frame_reg); |
c906108c SS |
473 | gen_offset (ax, frame_offset); |
474 | } | |
475 | ||
476 | ||
477 | /* Generate code to push the base address of the locals portion of the | |
478 | top stack frame. */ | |
479 | static void | |
480 | gen_frame_locals_address (ax) | |
481 | struct agent_expr *ax; | |
482 | { | |
483 | long frame_reg, frame_offset; | |
484 | ||
485 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
c5aa993b | 486 | ax_reg (ax, frame_reg); |
c906108c SS |
487 | gen_offset (ax, frame_offset); |
488 | } | |
489 | ||
490 | ||
491 | /* Generate code to add OFFSET to the top of the stack. Try to | |
492 | generate short and readable code. We use this for getting to | |
493 | variables on the stack, and structure members. If we were | |
494 | programming in ML, it would be clearer why these are the same | |
495 | thing. */ | |
496 | static void | |
497 | gen_offset (ax, offset) | |
498 | struct agent_expr *ax; | |
499 | int offset; | |
500 | { | |
501 | /* It would suffice to simply push the offset and add it, but this | |
502 | makes it easier to read positive and negative offsets in the | |
503 | bytecode. */ | |
504 | if (offset > 0) | |
505 | { | |
506 | ax_const_l (ax, offset); | |
507 | ax_simple (ax, aop_add); | |
508 | } | |
509 | else if (offset < 0) | |
510 | { | |
511 | ax_const_l (ax, -offset); | |
512 | ax_simple (ax, aop_sub); | |
513 | } | |
514 | } | |
515 | ||
516 | ||
517 | /* In many cases, a symbol's value is the offset from some other | |
518 | address (stack frame, base register, etc.) Generate code to add | |
519 | VAR's value to the top of the stack. */ | |
520 | static void | |
521 | gen_sym_offset (ax, var) | |
522 | struct agent_expr *ax; | |
523 | struct symbol *var; | |
524 | { | |
525 | gen_offset (ax, SYMBOL_VALUE (var)); | |
526 | } | |
527 | ||
528 | ||
529 | /* Generate code for a variable reference to AX. The variable is the | |
530 | symbol VAR. Set VALUE to describe the result. */ | |
531 | ||
532 | static void | |
533 | gen_var_ref (ax, value, var) | |
534 | struct agent_expr *ax; | |
535 | struct axs_value *value; | |
536 | struct symbol *var; | |
537 | { | |
538 | /* Dereference any typedefs. */ | |
539 | value->type = check_typedef (SYMBOL_TYPE (var)); | |
540 | ||
541 | /* I'm imitating the code in read_var_value. */ | |
542 | switch (SYMBOL_CLASS (var)) | |
543 | { | |
544 | case LOC_CONST: /* A constant, like an enum value. */ | |
545 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE (var)); | |
546 | value->kind = axs_rvalue; | |
547 | break; | |
548 | ||
549 | case LOC_LABEL: /* A goto label, being used as a value. */ | |
550 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE_ADDRESS (var)); | |
551 | value->kind = axs_rvalue; | |
552 | break; | |
553 | ||
554 | case LOC_CONST_BYTES: | |
6426a772 | 555 | internal_error ("ax-gdb.c (gen_var_ref): LOC_CONST_BYTES symbols are not supported"); |
c906108c SS |
556 | |
557 | /* Variable at a fixed location in memory. Easy. */ | |
558 | case LOC_STATIC: | |
559 | /* Push the address of the variable. */ | |
560 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (var)); | |
561 | value->kind = axs_lvalue_memory; | |
562 | break; | |
563 | ||
564 | case LOC_ARG: /* var lives in argument area of frame */ | |
565 | gen_frame_args_address (ax); | |
566 | gen_sym_offset (ax, var); | |
567 | value->kind = axs_lvalue_memory; | |
568 | break; | |
569 | ||
570 | case LOC_REF_ARG: /* As above, but the frame slot really | |
571 | holds the address of the variable. */ | |
572 | gen_frame_args_address (ax); | |
573 | gen_sym_offset (ax, var); | |
574 | /* Don't assume any particular pointer size. */ | |
575 | gen_fetch (ax, lookup_pointer_type (builtin_type_void)); | |
576 | value->kind = axs_lvalue_memory; | |
577 | break; | |
578 | ||
579 | case LOC_LOCAL: /* var lives in locals area of frame */ | |
580 | case LOC_LOCAL_ARG: | |
581 | gen_frame_locals_address (ax); | |
582 | gen_sym_offset (ax, var); | |
583 | value->kind = axs_lvalue_memory; | |
584 | break; | |
585 | ||
586 | case LOC_BASEREG: /* relative to some base register */ | |
587 | case LOC_BASEREG_ARG: | |
588 | ax_reg (ax, SYMBOL_BASEREG (var)); | |
589 | gen_sym_offset (ax, var); | |
590 | value->kind = axs_lvalue_memory; | |
591 | break; | |
592 | ||
593 | case LOC_TYPEDEF: | |
594 | error ("Cannot compute value of typedef `%s'.", | |
595 | SYMBOL_SOURCE_NAME (var)); | |
596 | break; | |
597 | ||
598 | case LOC_BLOCK: | |
599 | ax_const_l (ax, BLOCK_START (SYMBOL_BLOCK_VALUE (var))); | |
600 | value->kind = axs_rvalue; | |
601 | break; | |
602 | ||
603 | case LOC_REGISTER: | |
604 | case LOC_REGPARM: | |
605 | /* Don't generate any code at all; in the process of treating | |
606 | this as an lvalue or rvalue, the caller will generate the | |
607 | right code. */ | |
608 | value->kind = axs_lvalue_register; | |
609 | value->u.reg = SYMBOL_VALUE (var); | |
610 | break; | |
611 | ||
612 | /* A lot like LOC_REF_ARG, but the pointer lives directly in a | |
c5aa993b JM |
613 | register, not on the stack. Simpler than LOC_REGISTER and |
614 | LOC_REGPARM, because it's just like any other case where the | |
615 | thing has a real address. */ | |
c906108c SS |
616 | case LOC_REGPARM_ADDR: |
617 | ax_reg (ax, SYMBOL_VALUE (var)); | |
618 | value->kind = axs_lvalue_memory; | |
619 | break; | |
620 | ||
621 | case LOC_UNRESOLVED: | |
622 | { | |
c5aa993b JM |
623 | struct minimal_symbol *msym |
624 | = lookup_minimal_symbol (SYMBOL_NAME (var), NULL, NULL); | |
625 | if (!msym) | |
c906108c | 626 | error ("Couldn't resolve symbol `%s'.", SYMBOL_SOURCE_NAME (var)); |
c5aa993b | 627 | |
c906108c SS |
628 | /* Push the address of the variable. */ |
629 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (msym)); | |
630 | value->kind = axs_lvalue_memory; | |
631 | } | |
c5aa993b | 632 | break; |
c906108c SS |
633 | |
634 | case LOC_OPTIMIZED_OUT: | |
635 | error ("The variable `%s' has been optimized out.", | |
636 | SYMBOL_SOURCE_NAME (var)); | |
637 | break; | |
638 | ||
639 | default: | |
640 | error ("Cannot find value of botched symbol `%s'.", | |
641 | SYMBOL_SOURCE_NAME (var)); | |
642 | break; | |
643 | } | |
644 | } | |
c5aa993b | 645 | \f |
c906108c SS |
646 | |
647 | ||
c906108c SS |
648 | /* Generating bytecode from GDB expressions: literals */ |
649 | ||
650 | static void | |
651 | gen_int_literal (ax, value, k, type) | |
652 | struct agent_expr *ax; | |
653 | struct axs_value *value; | |
654 | LONGEST k; | |
655 | struct type *type; | |
656 | { | |
657 | ax_const_l (ax, k); | |
658 | value->kind = axs_rvalue; | |
659 | value->type = type; | |
660 | } | |
c5aa993b | 661 | \f |
c906108c SS |
662 | |
663 | ||
c906108c SS |
664 | /* Generating bytecode from GDB expressions: unary conversions, casts */ |
665 | ||
666 | /* Take what's on the top of the stack (as described by VALUE), and | |
667 | try to make an rvalue out of it. Signal an error if we can't do | |
668 | that. */ | |
669 | static void | |
670 | require_rvalue (ax, value) | |
671 | struct agent_expr *ax; | |
672 | struct axs_value *value; | |
673 | { | |
674 | switch (value->kind) | |
675 | { | |
676 | case axs_rvalue: | |
677 | /* It's already an rvalue. */ | |
678 | break; | |
679 | ||
680 | case axs_lvalue_memory: | |
681 | /* The top of stack is the address of the object. Dereference. */ | |
682 | gen_fetch (ax, value->type); | |
683 | break; | |
684 | ||
685 | case axs_lvalue_register: | |
686 | /* There's nothing on the stack, but value->u.reg is the | |
687 | register number containing the value. | |
688 | ||
c5aa993b JM |
689 | When we add floating-point support, this is going to have to |
690 | change. What about SPARC register pairs, for example? */ | |
c906108c SS |
691 | ax_reg (ax, value->u.reg); |
692 | gen_extend (ax, value->type); | |
693 | break; | |
694 | } | |
695 | ||
696 | value->kind = axs_rvalue; | |
697 | } | |
698 | ||
699 | ||
700 | /* Assume the top of the stack is described by VALUE, and perform the | |
701 | usual unary conversions. This is motivated by ANSI 6.2.2, but of | |
702 | course GDB expressions are not ANSI; they're the mishmash union of | |
703 | a bunch of languages. Rah. | |
704 | ||
705 | NOTE! This function promises to produce an rvalue only when the | |
706 | incoming value is of an appropriate type. In other words, the | |
707 | consumer of the value this function produces may assume the value | |
708 | is an rvalue only after checking its type. | |
709 | ||
710 | The immediate issue is that if the user tries to use a structure or | |
711 | union as an operand of, say, the `+' operator, we don't want to try | |
712 | to convert that structure to an rvalue; require_rvalue will bomb on | |
713 | structs and unions. Rather, we want to simply pass the struct | |
714 | lvalue through unchanged, and let `+' raise an error. */ | |
715 | ||
716 | static void | |
717 | gen_usual_unary (ax, value) | |
718 | struct agent_expr *ax; | |
719 | struct axs_value *value; | |
720 | { | |
721 | /* We don't have to generate any code for the usual integral | |
722 | conversions, since values are always represented as full-width on | |
723 | the stack. Should we tweak the type? */ | |
724 | ||
725 | /* Some types require special handling. */ | |
726 | switch (value->type->code) | |
727 | { | |
728 | /* Functions get converted to a pointer to the function. */ | |
729 | case TYPE_CODE_FUNC: | |
730 | value->type = lookup_pointer_type (value->type); | |
731 | value->kind = axs_rvalue; /* Should always be true, but just in case. */ | |
732 | break; | |
733 | ||
734 | /* Arrays get converted to a pointer to their first element, and | |
c5aa993b | 735 | are no longer an lvalue. */ |
c906108c SS |
736 | case TYPE_CODE_ARRAY: |
737 | { | |
738 | struct type *elements = TYPE_TARGET_TYPE (value->type); | |
739 | value->type = lookup_pointer_type (elements); | |
740 | value->kind = axs_rvalue; | |
741 | /* We don't need to generate any code; the address of the array | |
742 | is also the address of its first element. */ | |
743 | } | |
c5aa993b | 744 | break; |
c906108c | 745 | |
c5aa993b JM |
746 | /* Don't try to convert structures and unions to rvalues. Let the |
747 | consumer signal an error. */ | |
c906108c SS |
748 | case TYPE_CODE_STRUCT: |
749 | case TYPE_CODE_UNION: | |
750 | return; | |
751 | ||
752 | /* If the value is an enum, call it an integer. */ | |
753 | case TYPE_CODE_ENUM: | |
754 | value->type = builtin_type_int; | |
755 | break; | |
756 | } | |
757 | ||
758 | /* If the value is an lvalue, dereference it. */ | |
759 | require_rvalue (ax, value); | |
760 | } | |
761 | ||
762 | ||
763 | /* Return non-zero iff the type TYPE1 is considered "wider" than the | |
764 | type TYPE2, according to the rules described in gen_usual_arithmetic. */ | |
765 | static int | |
766 | type_wider_than (type1, type2) | |
767 | struct type *type1, *type2; | |
768 | { | |
769 | return (TYPE_LENGTH (type1) > TYPE_LENGTH (type2) | |
770 | || (TYPE_LENGTH (type1) == TYPE_LENGTH (type2) | |
771 | && TYPE_UNSIGNED (type1) | |
c5aa993b | 772 | && !TYPE_UNSIGNED (type2))); |
c906108c SS |
773 | } |
774 | ||
775 | ||
776 | /* Return the "wider" of the two types TYPE1 and TYPE2. */ | |
777 | static struct type * | |
778 | max_type (type1, type2) | |
779 | struct type *type1, *type2; | |
780 | { | |
781 | return type_wider_than (type1, type2) ? type1 : type2; | |
782 | } | |
783 | ||
784 | ||
785 | /* Generate code to convert a scalar value of type FROM to type TO. */ | |
786 | static void | |
787 | gen_conversion (ax, from, to) | |
788 | struct agent_expr *ax; | |
789 | struct type *from, *to; | |
790 | { | |
791 | /* Perhaps there is a more graceful way to state these rules. */ | |
792 | ||
793 | /* If we're converting to a narrower type, then we need to clear out | |
794 | the upper bits. */ | |
795 | if (TYPE_LENGTH (to) < TYPE_LENGTH (from)) | |
796 | gen_extend (ax, from); | |
797 | ||
798 | /* If the two values have equal width, but different signednesses, | |
799 | then we need to extend. */ | |
800 | else if (TYPE_LENGTH (to) == TYPE_LENGTH (from)) | |
801 | { | |
802 | if (TYPE_UNSIGNED (from) != TYPE_UNSIGNED (to)) | |
803 | gen_extend (ax, to); | |
804 | } | |
805 | ||
806 | /* If we're converting to a wider type, and becoming unsigned, then | |
807 | we need to zero out any possible sign bits. */ | |
808 | else if (TYPE_LENGTH (to) > TYPE_LENGTH (from)) | |
809 | { | |
810 | if (TYPE_UNSIGNED (to)) | |
811 | gen_extend (ax, to); | |
812 | } | |
813 | } | |
814 | ||
815 | ||
816 | /* Return non-zero iff the type FROM will require any bytecodes to be | |
817 | emitted to be converted to the type TO. */ | |
818 | static int | |
819 | is_nontrivial_conversion (from, to) | |
820 | struct type *from, *to; | |
821 | { | |
822 | struct agent_expr *ax = new_agent_expr (0); | |
823 | int nontrivial; | |
824 | ||
825 | /* Actually generate the code, and see if anything came out. At the | |
826 | moment, it would be trivial to replicate the code in | |
827 | gen_conversion here, but in the future, when we're supporting | |
828 | floating point and the like, it may not be. Doing things this | |
829 | way allows this function to be independent of the logic in | |
830 | gen_conversion. */ | |
831 | gen_conversion (ax, from, to); | |
832 | nontrivial = ax->len > 0; | |
833 | free_agent_expr (ax); | |
834 | return nontrivial; | |
835 | } | |
836 | ||
837 | ||
838 | /* Generate code to perform the "usual arithmetic conversions" (ANSI C | |
839 | 6.2.1.5) for the two operands of an arithmetic operator. This | |
840 | effectively finds a "least upper bound" type for the two arguments, | |
841 | and promotes each argument to that type. *VALUE1 and *VALUE2 | |
842 | describe the values as they are passed in, and as they are left. */ | |
843 | static void | |
844 | gen_usual_arithmetic (ax, value1, value2) | |
845 | struct agent_expr *ax; | |
846 | struct axs_value *value1, *value2; | |
847 | { | |
848 | /* Do the usual binary conversions. */ | |
849 | if (TYPE_CODE (value1->type) == TYPE_CODE_INT | |
850 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
851 | { | |
852 | /* The ANSI integral promotions seem to work this way: Order the | |
c5aa993b JM |
853 | integer types by size, and then by signedness: an n-bit |
854 | unsigned type is considered "wider" than an n-bit signed | |
855 | type. Promote to the "wider" of the two types, and always | |
856 | promote at least to int. */ | |
c906108c SS |
857 | struct type *target = max_type (builtin_type_int, |
858 | max_type (value1->type, value2->type)); | |
859 | ||
860 | /* Deal with value2, on the top of the stack. */ | |
861 | gen_conversion (ax, value2->type, target); | |
862 | ||
863 | /* Deal with value1, not on the top of the stack. Don't | |
864 | generate the `swap' instructions if we're not actually going | |
865 | to do anything. */ | |
866 | if (is_nontrivial_conversion (value1->type, target)) | |
867 | { | |
868 | ax_simple (ax, aop_swap); | |
869 | gen_conversion (ax, value1->type, target); | |
870 | ax_simple (ax, aop_swap); | |
871 | } | |
872 | ||
873 | value1->type = value2->type = target; | |
874 | } | |
875 | } | |
876 | ||
877 | ||
878 | /* Generate code to perform the integral promotions (ANSI 6.2.1.1) on | |
879 | the value on the top of the stack, as described by VALUE. Assume | |
880 | the value has integral type. */ | |
881 | static void | |
882 | gen_integral_promotions (ax, value) | |
883 | struct agent_expr *ax; | |
884 | struct axs_value *value; | |
885 | { | |
c5aa993b | 886 | if (!type_wider_than (value->type, builtin_type_int)) |
c906108c SS |
887 | { |
888 | gen_conversion (ax, value->type, builtin_type_int); | |
889 | value->type = builtin_type_int; | |
890 | } | |
c5aa993b | 891 | else if (!type_wider_than (value->type, builtin_type_unsigned_int)) |
c906108c SS |
892 | { |
893 | gen_conversion (ax, value->type, builtin_type_unsigned_int); | |
894 | value->type = builtin_type_unsigned_int; | |
895 | } | |
896 | } | |
897 | ||
898 | ||
899 | /* Generate code for a cast to TYPE. */ | |
900 | static void | |
901 | gen_cast (ax, value, type) | |
902 | struct agent_expr *ax; | |
903 | struct axs_value *value; | |
904 | struct type *type; | |
905 | { | |
906 | /* GCC does allow casts to yield lvalues, so this should be fixed | |
907 | before merging these changes into the trunk. */ | |
908 | require_rvalue (ax, value); | |
909 | /* Dereference typedefs. */ | |
910 | type = check_typedef (type); | |
911 | ||
912 | switch (type->code) | |
913 | { | |
914 | case TYPE_CODE_PTR: | |
915 | /* It's implementation-defined, and I'll bet this is what GCC | |
916 | does. */ | |
917 | break; | |
918 | ||
919 | case TYPE_CODE_ARRAY: | |
920 | case TYPE_CODE_STRUCT: | |
921 | case TYPE_CODE_UNION: | |
922 | case TYPE_CODE_FUNC: | |
923 | error ("Illegal type cast: intended type must be scalar."); | |
924 | ||
925 | case TYPE_CODE_ENUM: | |
926 | /* We don't have to worry about the size of the value, because | |
927 | all our integral values are fully sign-extended, and when | |
928 | casting pointers we can do anything we like. Is there any | |
929 | way for us to actually know what GCC actually does with a | |
930 | cast like this? */ | |
931 | value->type = type; | |
932 | break; | |
c5aa993b | 933 | |
c906108c SS |
934 | case TYPE_CODE_INT: |
935 | gen_conversion (ax, value->type, type); | |
936 | break; | |
937 | ||
938 | case TYPE_CODE_VOID: | |
939 | /* We could pop the value, and rely on everyone else to check | |
c5aa993b JM |
940 | the type and notice that this value doesn't occupy a stack |
941 | slot. But for now, leave the value on the stack, and | |
942 | preserve the "value == stack element" assumption. */ | |
c906108c SS |
943 | break; |
944 | ||
945 | default: | |
946 | error ("Casts to requested type are not yet implemented."); | |
947 | } | |
948 | ||
949 | value->type = type; | |
950 | } | |
c5aa993b | 951 | \f |
c906108c SS |
952 | |
953 | ||
c906108c SS |
954 | /* Generating bytecode from GDB expressions: arithmetic */ |
955 | ||
956 | /* Scale the integer on the top of the stack by the size of the target | |
957 | of the pointer type TYPE. */ | |
958 | static void | |
959 | gen_scale (ax, op, type) | |
960 | struct agent_expr *ax; | |
961 | enum agent_op op; | |
962 | struct type *type; | |
963 | { | |
964 | struct type *element = TYPE_TARGET_TYPE (type); | |
965 | ||
966 | if (element->length != 1) | |
967 | { | |
968 | ax_const_l (ax, element->length); | |
969 | ax_simple (ax, op); | |
970 | } | |
971 | } | |
972 | ||
973 | ||
974 | /* Generate code for an addition; non-trivial because we deal with | |
975 | pointer arithmetic. We set VALUE to describe the result value; we | |
976 | assume VALUE1 and VALUE2 describe the two operands, and that | |
977 | they've undergone the usual binary conversions. Used by both | |
978 | BINOP_ADD and BINOP_SUBSCRIPT. NAME is used in error messages. */ | |
979 | static void | |
980 | gen_add (ax, value, value1, value2, name) | |
981 | struct agent_expr *ax; | |
982 | struct axs_value *value, *value1, *value2; | |
983 | char *name; | |
984 | { | |
985 | /* Is it INT+PTR? */ | |
986 | if (value1->type->code == TYPE_CODE_INT | |
987 | && value2->type->code == TYPE_CODE_PTR) | |
988 | { | |
989 | /* Swap the values and proceed normally. */ | |
990 | ax_simple (ax, aop_swap); | |
991 | gen_scale (ax, aop_mul, value2->type); | |
992 | ax_simple (ax, aop_add); | |
c5aa993b | 993 | gen_extend (ax, value2->type); /* Catch overflow. */ |
c906108c SS |
994 | value->type = value2->type; |
995 | } | |
996 | ||
997 | /* Is it PTR+INT? */ | |
998 | else if (value1->type->code == TYPE_CODE_PTR | |
999 | && value2->type->code == TYPE_CODE_INT) | |
1000 | { | |
1001 | gen_scale (ax, aop_mul, value1->type); | |
1002 | ax_simple (ax, aop_add); | |
c5aa993b | 1003 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1004 | value->type = value1->type; |
1005 | } | |
1006 | ||
1007 | /* Must be number + number; the usual binary conversions will have | |
1008 | brought them both to the same width. */ | |
1009 | else if (value1->type->code == TYPE_CODE_INT | |
1010 | && value2->type->code == TYPE_CODE_INT) | |
1011 | { | |
1012 | ax_simple (ax, aop_add); | |
c5aa993b | 1013 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1014 | value->type = value1->type; |
1015 | } | |
1016 | ||
1017 | else | |
1018 | error ("Illegal combination of types in %s.", name); | |
1019 | ||
1020 | value->kind = axs_rvalue; | |
1021 | } | |
1022 | ||
1023 | ||
1024 | /* Generate code for an addition; non-trivial because we have to deal | |
1025 | with pointer arithmetic. We set VALUE to describe the result | |
1026 | value; we assume VALUE1 and VALUE2 describe the two operands, and | |
1027 | that they've undergone the usual binary conversions. */ | |
1028 | static void | |
1029 | gen_sub (ax, value, value1, value2) | |
1030 | struct agent_expr *ax; | |
1031 | struct axs_value *value, *value1, *value2; | |
1032 | { | |
c906108c SS |
1033 | if (value1->type->code == TYPE_CODE_PTR) |
1034 | { | |
1035 | /* Is it PTR - INT? */ | |
1036 | if (value2->type->code == TYPE_CODE_INT) | |
1037 | { | |
1038 | gen_scale (ax, aop_mul, value1->type); | |
1039 | ax_simple (ax, aop_sub); | |
c5aa993b | 1040 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1041 | value->type = value1->type; |
1042 | } | |
1043 | ||
1044 | /* Is it PTR - PTR? Strictly speaking, the types ought to | |
c5aa993b JM |
1045 | match, but this is what the normal GDB expression evaluator |
1046 | tests for. */ | |
c906108c SS |
1047 | else if (value2->type->code == TYPE_CODE_PTR |
1048 | && (TYPE_LENGTH (TYPE_TARGET_TYPE (value1->type)) | |
1049 | == TYPE_LENGTH (TYPE_TARGET_TYPE (value2->type)))) | |
1050 | { | |
1051 | ax_simple (ax, aop_sub); | |
1052 | gen_scale (ax, aop_div_unsigned, value1->type); | |
c5aa993b | 1053 | value->type = builtin_type_long; /* FIXME --- should be ptrdiff_t */ |
c906108c SS |
1054 | } |
1055 | else | |
1056 | error ("\ | |
1057 | First argument of `-' is a pointer, but second argument is neither\n\ | |
1058 | an integer nor a pointer of the same type."); | |
1059 | } | |
1060 | ||
1061 | /* Must be number + number. */ | |
1062 | else if (value1->type->code == TYPE_CODE_INT | |
1063 | && value2->type->code == TYPE_CODE_INT) | |
1064 | { | |
1065 | ax_simple (ax, aop_sub); | |
c5aa993b | 1066 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1067 | value->type = value1->type; |
1068 | } | |
c5aa993b | 1069 | |
c906108c SS |
1070 | else |
1071 | error ("Illegal combination of types in subtraction."); | |
1072 | ||
1073 | value->kind = axs_rvalue; | |
1074 | } | |
1075 | ||
1076 | /* Generate code for a binary operator that doesn't do pointer magic. | |
1077 | We set VALUE to describe the result value; we assume VALUE1 and | |
1078 | VALUE2 describe the two operands, and that they've undergone the | |
1079 | usual binary conversions. MAY_CARRY should be non-zero iff the | |
1080 | result needs to be extended. NAME is the English name of the | |
1081 | operator, used in error messages */ | |
1082 | static void | |
1083 | gen_binop (ax, value, value1, value2, op, op_unsigned, may_carry, name) | |
1084 | struct agent_expr *ax; | |
1085 | struct axs_value *value, *value1, *value2; | |
1086 | enum agent_op op, op_unsigned; | |
1087 | int may_carry; | |
1088 | char *name; | |
1089 | { | |
1090 | /* We only handle INT op INT. */ | |
1091 | if ((value1->type->code != TYPE_CODE_INT) | |
1092 | || (value2->type->code != TYPE_CODE_INT)) | |
1093 | error ("Illegal combination of types in %s.", name); | |
c5aa993b | 1094 | |
c906108c SS |
1095 | ax_simple (ax, |
1096 | TYPE_UNSIGNED (value1->type) ? op_unsigned : op); | |
1097 | if (may_carry) | |
c5aa993b | 1098 | gen_extend (ax, value1->type); /* catch overflow */ |
c906108c SS |
1099 | value->type = value1->type; |
1100 | value->kind = axs_rvalue; | |
1101 | } | |
1102 | ||
1103 | ||
1104 | static void | |
1105 | gen_logical_not (ax, value) | |
1106 | struct agent_expr *ax; | |
1107 | struct axs_value *value; | |
1108 | { | |
1109 | if (TYPE_CODE (value->type) != TYPE_CODE_INT | |
1110 | && TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1111 | error ("Illegal type of operand to `!'."); | |
1112 | ||
1113 | gen_usual_unary (ax, value); | |
1114 | ax_simple (ax, aop_log_not); | |
1115 | value->type = builtin_type_int; | |
1116 | } | |
1117 | ||
1118 | ||
1119 | static void | |
1120 | gen_complement (ax, value) | |
1121 | struct agent_expr *ax; | |
1122 | struct axs_value *value; | |
1123 | { | |
1124 | if (TYPE_CODE (value->type) != TYPE_CODE_INT) | |
1125 | error ("Illegal type of operand to `~'."); | |
1126 | ||
1127 | gen_usual_unary (ax, value); | |
1128 | gen_integral_promotions (ax, value); | |
1129 | ax_simple (ax, aop_bit_not); | |
1130 | gen_extend (ax, value->type); | |
1131 | } | |
c5aa993b | 1132 | \f |
c906108c SS |
1133 | |
1134 | ||
c906108c SS |
1135 | /* Generating bytecode from GDB expressions: * & . -> @ sizeof */ |
1136 | ||
1137 | /* Dereference the value on the top of the stack. */ | |
1138 | static void | |
1139 | gen_deref (ax, value) | |
1140 | struct agent_expr *ax; | |
1141 | struct axs_value *value; | |
1142 | { | |
1143 | /* The caller should check the type, because several operators use | |
1144 | this, and we don't know what error message to generate. */ | |
1145 | if (value->type->code != TYPE_CODE_PTR) | |
6426a772 | 1146 | internal_error ("ax-gdb.c (gen_deref): expected a pointer"); |
c906108c SS |
1147 | |
1148 | /* We've got an rvalue now, which is a pointer. We want to yield an | |
1149 | lvalue, whose address is exactly that pointer. So we don't | |
1150 | actually emit any code; we just change the type from "Pointer to | |
1151 | T" to "T", and mark the value as an lvalue in memory. Leave it | |
1152 | to the consumer to actually dereference it. */ | |
1153 | value->type = check_typedef (TYPE_TARGET_TYPE (value->type)); | |
1154 | value->kind = ((value->type->code == TYPE_CODE_FUNC) | |
1155 | ? axs_rvalue : axs_lvalue_memory); | |
1156 | } | |
1157 | ||
1158 | ||
1159 | /* Produce the address of the lvalue on the top of the stack. */ | |
1160 | static void | |
1161 | gen_address_of (ax, value) | |
1162 | struct agent_expr *ax; | |
1163 | struct axs_value *value; | |
1164 | { | |
1165 | /* Special case for taking the address of a function. The ANSI | |
1166 | standard describes this as a special case, too, so this | |
1167 | arrangement is not without motivation. */ | |
1168 | if (value->type->code == TYPE_CODE_FUNC) | |
1169 | /* The value's already an rvalue on the stack, so we just need to | |
1170 | change the type. */ | |
1171 | value->type = lookup_pointer_type (value->type); | |
1172 | else | |
1173 | switch (value->kind) | |
1174 | { | |
1175 | case axs_rvalue: | |
1176 | error ("Operand of `&' is an rvalue, which has no address."); | |
1177 | ||
1178 | case axs_lvalue_register: | |
1179 | error ("Operand of `&' is in a register, and has no address."); | |
1180 | ||
1181 | case axs_lvalue_memory: | |
1182 | value->kind = axs_rvalue; | |
1183 | value->type = lookup_pointer_type (value->type); | |
1184 | break; | |
1185 | } | |
1186 | } | |
1187 | ||
1188 | ||
1189 | /* A lot of this stuff will have to change to support C++. But we're | |
1190 | not going to deal with that at the moment. */ | |
1191 | ||
1192 | /* Find the field in the structure type TYPE named NAME, and return | |
1193 | its index in TYPE's field array. */ | |
1194 | static int | |
1195 | find_field (type, name) | |
1196 | struct type *type; | |
1197 | char *name; | |
1198 | { | |
1199 | int i; | |
1200 | ||
1201 | CHECK_TYPEDEF (type); | |
1202 | ||
1203 | /* Make sure this isn't C++. */ | |
1204 | if (TYPE_N_BASECLASSES (type) != 0) | |
6426a772 | 1205 | internal_error ("ax-gdb.c (find_field): derived classes supported"); |
c906108c SS |
1206 | |
1207 | for (i = 0; i < TYPE_NFIELDS (type); i++) | |
1208 | { | |
1209 | char *this_name = TYPE_FIELD_NAME (type, i); | |
1210 | ||
1211 | if (this_name && STREQ (name, this_name)) | |
1212 | return i; | |
1213 | ||
1214 | if (this_name[0] == '\0') | |
6426a772 | 1215 | internal_error ("ax-gdb.c (find_field): anonymous unions not supported"); |
c906108c SS |
1216 | } |
1217 | ||
1218 | error ("Couldn't find member named `%s' in struct/union `%s'", | |
1219 | name, type->tag_name); | |
1220 | ||
1221 | return 0; | |
1222 | } | |
1223 | ||
1224 | ||
1225 | /* Generate code to push the value of a bitfield of a structure whose | |
1226 | address is on the top of the stack. START and END give the | |
1227 | starting and one-past-ending *bit* numbers of the field within the | |
1228 | structure. */ | |
1229 | static void | |
1230 | gen_bitfield_ref (ax, value, type, start, end) | |
1231 | struct agent_expr *ax; | |
1232 | struct axs_value *value; | |
1233 | struct type *type; | |
1234 | int start, end; | |
1235 | { | |
1236 | /* Note that ops[i] fetches 8 << i bits. */ | |
1237 | static enum agent_op ops[] | |
c5aa993b JM |
1238 | = |
1239 | {aop_ref8, aop_ref16, aop_ref32, aop_ref64}; | |
c906108c SS |
1240 | static int num_ops = (sizeof (ops) / sizeof (ops[0])); |
1241 | ||
1242 | /* We don't want to touch any byte that the bitfield doesn't | |
1243 | actually occupy; we shouldn't make any accesses we're not | |
1244 | explicitly permitted to. We rely here on the fact that the | |
1245 | bytecode `ref' operators work on unaligned addresses. | |
1246 | ||
1247 | It takes some fancy footwork to get the stack to work the way | |
1248 | we'd like. Say we're retrieving a bitfield that requires three | |
1249 | fetches. Initially, the stack just contains the address: | |
c5aa993b | 1250 | addr |
c906108c | 1251 | For the first fetch, we duplicate the address |
c5aa993b | 1252 | addr addr |
c906108c SS |
1253 | then add the byte offset, do the fetch, and shift and mask as |
1254 | needed, yielding a fragment of the value, properly aligned for | |
1255 | the final bitwise or: | |
c5aa993b | 1256 | addr frag1 |
c906108c | 1257 | then we swap, and repeat the process: |
c5aa993b JM |
1258 | frag1 addr --- address on top |
1259 | frag1 addr addr --- duplicate it | |
1260 | frag1 addr frag2 --- get second fragment | |
1261 | frag1 frag2 addr --- swap again | |
1262 | frag1 frag2 frag3 --- get third fragment | |
c906108c SS |
1263 | Notice that, since the third fragment is the last one, we don't |
1264 | bother duplicating the address this time. Now we have all the | |
1265 | fragments on the stack, and we can simply `or' them together, | |
1266 | yielding the final value of the bitfield. */ | |
1267 | ||
1268 | /* The first and one-after-last bits in the field, but rounded down | |
1269 | and up to byte boundaries. */ | |
1270 | int bound_start = (start / TARGET_CHAR_BIT) * TARGET_CHAR_BIT; | |
c5aa993b JM |
1271 | int bound_end = (((end + TARGET_CHAR_BIT - 1) |
1272 | / TARGET_CHAR_BIT) | |
1273 | * TARGET_CHAR_BIT); | |
c906108c SS |
1274 | |
1275 | /* current bit offset within the structure */ | |
1276 | int offset; | |
1277 | ||
1278 | /* The index in ops of the opcode we're considering. */ | |
1279 | int op; | |
1280 | ||
1281 | /* The number of fragments we generated in the process. Probably | |
1282 | equal to the number of `one' bits in bytesize, but who cares? */ | |
1283 | int fragment_count; | |
1284 | ||
1285 | /* Dereference any typedefs. */ | |
1286 | type = check_typedef (type); | |
1287 | ||
1288 | /* Can we fetch the number of bits requested at all? */ | |
1289 | if ((end - start) > ((1 << num_ops) * 8)) | |
6426a772 | 1290 | internal_error ("ax-gdb.c (gen_bitfield_ref): bitfield too wide"); |
c906108c SS |
1291 | |
1292 | /* Note that we know here that we only need to try each opcode once. | |
1293 | That may not be true on machines with weird byte sizes. */ | |
1294 | offset = bound_start; | |
1295 | fragment_count = 0; | |
1296 | for (op = num_ops - 1; op >= 0; op--) | |
1297 | { | |
1298 | /* number of bits that ops[op] would fetch */ | |
1299 | int op_size = 8 << op; | |
1300 | ||
1301 | /* The stack at this point, from bottom to top, contains zero or | |
c5aa993b JM |
1302 | more fragments, then the address. */ |
1303 | ||
c906108c SS |
1304 | /* Does this fetch fit within the bitfield? */ |
1305 | if (offset + op_size <= bound_end) | |
1306 | { | |
1307 | /* Is this the last fragment? */ | |
1308 | int last_frag = (offset + op_size == bound_end); | |
1309 | ||
c5aa993b JM |
1310 | if (!last_frag) |
1311 | ax_simple (ax, aop_dup); /* keep a copy of the address */ | |
1312 | ||
c906108c SS |
1313 | /* Add the offset. */ |
1314 | gen_offset (ax, offset / TARGET_CHAR_BIT); | |
1315 | ||
1316 | if (trace_kludge) | |
1317 | { | |
1318 | /* Record the area of memory we're about to fetch. */ | |
1319 | ax_trace_quick (ax, op_size / TARGET_CHAR_BIT); | |
1320 | } | |
1321 | ||
1322 | /* Perform the fetch. */ | |
1323 | ax_simple (ax, ops[op]); | |
c5aa993b JM |
1324 | |
1325 | /* Shift the bits we have to their proper position. | |
c906108c SS |
1326 | gen_left_shift will generate right shifts when the operand |
1327 | is negative. | |
1328 | ||
c5aa993b JM |
1329 | A big-endian field diagram to ponder: |
1330 | byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7 | |
1331 | +------++------++------++------++------++------++------++------+ | |
1332 | xxxxAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBCCCCCxxxxxxxxxxx | |
1333 | ^ ^ ^ ^ | |
1334 | bit number 16 32 48 53 | |
c906108c SS |
1335 | These are bit numbers as supplied by GDB. Note that the |
1336 | bit numbers run from right to left once you've fetched the | |
1337 | value! | |
1338 | ||
c5aa993b JM |
1339 | A little-endian field diagram to ponder: |
1340 | byte 7 byte 6 byte 5 byte 4 byte 3 byte 2 byte 1 byte 0 | |
1341 | +------++------++------++------++------++------++------++------+ | |
1342 | xxxxxxxxxxxAAAAABBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCCCCCCCCCCCCCxxxx | |
1343 | ^ ^ ^ ^ ^ | |
1344 | bit number 48 32 16 4 0 | |
1345 | ||
1346 | In both cases, the most significant end is on the left | |
1347 | (i.e. normal numeric writing order), which means that you | |
1348 | don't go crazy thinking about `left' and `right' shifts. | |
1349 | ||
1350 | We don't have to worry about masking yet: | |
1351 | - If they contain garbage off the least significant end, then we | |
1352 | must be looking at the low end of the field, and the right | |
1353 | shift will wipe them out. | |
1354 | - If they contain garbage off the most significant end, then we | |
1355 | must be looking at the most significant end of the word, and | |
1356 | the sign/zero extension will wipe them out. | |
1357 | - If we're in the interior of the word, then there is no garbage | |
1358 | on either end, because the ref operators zero-extend. */ | |
c906108c SS |
1359 | if (TARGET_BYTE_ORDER == BIG_ENDIAN) |
1360 | gen_left_shift (ax, end - (offset + op_size)); | |
c5aa993b | 1361 | else |
c906108c SS |
1362 | gen_left_shift (ax, offset - start); |
1363 | ||
c5aa993b | 1364 | if (!last_frag) |
c906108c SS |
1365 | /* Bring the copy of the address up to the top. */ |
1366 | ax_simple (ax, aop_swap); | |
1367 | ||
1368 | offset += op_size; | |
1369 | fragment_count++; | |
1370 | } | |
1371 | } | |
1372 | ||
1373 | /* Generate enough bitwise `or' operations to combine all the | |
1374 | fragments we left on the stack. */ | |
1375 | while (fragment_count-- > 1) | |
1376 | ax_simple (ax, aop_bit_or); | |
1377 | ||
1378 | /* Sign- or zero-extend the value as appropriate. */ | |
1379 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, end - start)); | |
1380 | ||
1381 | /* This is *not* an lvalue. Ugh. */ | |
1382 | value->kind = axs_rvalue; | |
1383 | value->type = type; | |
1384 | } | |
1385 | ||
1386 | ||
1387 | /* Generate code to reference the member named FIELD of a structure or | |
1388 | union. The top of the stack, as described by VALUE, should have | |
1389 | type (pointer to a)* struct/union. OPERATOR_NAME is the name of | |
1390 | the operator being compiled, and OPERAND_NAME is the kind of thing | |
1391 | it operates on; we use them in error messages. */ | |
1392 | static void | |
1393 | gen_struct_ref (ax, value, field, operator_name, operand_name) | |
1394 | struct agent_expr *ax; | |
1395 | struct axs_value *value; | |
1396 | char *field; | |
1397 | char *operator_name; | |
1398 | char *operand_name; | |
1399 | { | |
1400 | struct type *type; | |
1401 | int i; | |
1402 | ||
1403 | /* Follow pointers until we reach a non-pointer. These aren't the C | |
1404 | semantics, but they're what the normal GDB evaluator does, so we | |
1405 | should at least be consistent. */ | |
1406 | while (value->type->code == TYPE_CODE_PTR) | |
1407 | { | |
1408 | gen_usual_unary (ax, value); | |
1409 | gen_deref (ax, value); | |
1410 | } | |
1411 | type = value->type; | |
1412 | ||
1413 | /* This must yield a structure or a union. */ | |
1414 | if (TYPE_CODE (type) != TYPE_CODE_STRUCT | |
1415 | && TYPE_CODE (type) != TYPE_CODE_UNION) | |
1416 | error ("The left operand of `%s' is not a %s.", | |
1417 | operator_name, operand_name); | |
1418 | ||
1419 | /* And it must be in memory; we don't deal with structure rvalues, | |
1420 | or structures living in registers. */ | |
1421 | if (value->kind != axs_lvalue_memory) | |
1422 | error ("Structure does not live in memory."); | |
1423 | ||
1424 | i = find_field (type, field); | |
c5aa993b | 1425 | |
c906108c SS |
1426 | /* Is this a bitfield? */ |
1427 | if (TYPE_FIELD_PACKED (type, i)) | |
1428 | gen_bitfield_ref (ax, value, TYPE_FIELD_TYPE (type, i), | |
1429 | TYPE_FIELD_BITPOS (type, i), | |
1430 | (TYPE_FIELD_BITPOS (type, i) | |
1431 | + TYPE_FIELD_BITSIZE (type, i))); | |
1432 | else | |
1433 | { | |
1434 | gen_offset (ax, TYPE_FIELD_BITPOS (type, i) / TARGET_CHAR_BIT); | |
1435 | value->kind = axs_lvalue_memory; | |
1436 | value->type = TYPE_FIELD_TYPE (type, i); | |
1437 | } | |
1438 | } | |
1439 | ||
1440 | ||
1441 | /* Generate code for GDB's magical `repeat' operator. | |
1442 | LVALUE @ INT creates an array INT elements long, and whose elements | |
1443 | have the same type as LVALUE, located in memory so that LVALUE is | |
1444 | its first element. For example, argv[0]@argc gives you the array | |
1445 | of command-line arguments. | |
1446 | ||
1447 | Unfortunately, because we have to know the types before we actually | |
1448 | have a value for the expression, we can't implement this perfectly | |
1449 | without changing the type system, having values that occupy two | |
1450 | stack slots, doing weird things with sizeof, etc. So we require | |
1451 | the right operand to be a constant expression. */ | |
1452 | static void | |
1453 | gen_repeat (pc, ax, value) | |
1454 | union exp_element **pc; | |
1455 | struct agent_expr *ax; | |
1456 | struct axs_value *value; | |
1457 | { | |
1458 | struct axs_value value1; | |
1459 | /* We don't want to turn this into an rvalue, so no conversions | |
1460 | here. */ | |
1461 | gen_expr (pc, ax, &value1); | |
1462 | if (value1.kind != axs_lvalue_memory) | |
1463 | error ("Left operand of `@' must be an object in memory."); | |
1464 | ||
1465 | /* Evaluate the length; it had better be a constant. */ | |
1466 | { | |
1467 | struct value *v = const_expr (pc); | |
1468 | int length; | |
1469 | ||
c5aa993b | 1470 | if (!v) |
c906108c SS |
1471 | error ("Right operand of `@' must be a constant, in agent expressions."); |
1472 | if (v->type->code != TYPE_CODE_INT) | |
1473 | error ("Right operand of `@' must be an integer."); | |
1474 | length = value_as_long (v); | |
1475 | if (length <= 0) | |
1476 | error ("Right operand of `@' must be positive."); | |
1477 | ||
1478 | /* The top of the stack is already the address of the object, so | |
1479 | all we need to do is frob the type of the lvalue. */ | |
1480 | { | |
1481 | /* FIXME-type-allocation: need a way to free this type when we are | |
c5aa993b | 1482 | done with it. */ |
c906108c | 1483 | struct type *range |
c5aa993b | 1484 | = create_range_type (0, builtin_type_int, 0, length - 1); |
c906108c SS |
1485 | struct type *array = create_array_type (0, value1.type, range); |
1486 | ||
1487 | value->kind = axs_lvalue_memory; | |
1488 | value->type = array; | |
1489 | } | |
1490 | } | |
1491 | } | |
1492 | ||
1493 | ||
1494 | /* Emit code for the `sizeof' operator. | |
1495 | *PC should point at the start of the operand expression; we advance it | |
1496 | to the first instruction after the operand. */ | |
1497 | static void | |
1498 | gen_sizeof (pc, ax, value) | |
1499 | union exp_element **pc; | |
1500 | struct agent_expr *ax; | |
1501 | struct axs_value *value; | |
1502 | { | |
1503 | /* We don't care about the value of the operand expression; we only | |
1504 | care about its type. However, in the current arrangement, the | |
1505 | only way to find an expression's type is to generate code for it. | |
1506 | So we generate code for the operand, and then throw it away, | |
1507 | replacing it with code that simply pushes its size. */ | |
1508 | int start = ax->len; | |
1509 | gen_expr (pc, ax, value); | |
1510 | ||
1511 | /* Throw away the code we just generated. */ | |
1512 | ax->len = start; | |
c5aa993b | 1513 | |
c906108c SS |
1514 | ax_const_l (ax, TYPE_LENGTH (value->type)); |
1515 | value->kind = axs_rvalue; | |
1516 | value->type = builtin_type_int; | |
1517 | } | |
c906108c | 1518 | \f |
c5aa993b | 1519 | |
c906108c SS |
1520 | /* Generating bytecode from GDB expressions: general recursive thingy */ |
1521 | ||
1522 | /* A gen_expr function written by a Gen-X'er guy. | |
1523 | Append code for the subexpression of EXPR starting at *POS_P to AX. */ | |
1524 | static void | |
1525 | gen_expr (pc, ax, value) | |
1526 | union exp_element **pc; | |
1527 | struct agent_expr *ax; | |
1528 | struct axs_value *value; | |
1529 | { | |
1530 | /* Used to hold the descriptions of operand expressions. */ | |
1531 | struct axs_value value1, value2; | |
1532 | enum exp_opcode op = (*pc)[0].opcode; | |
1533 | ||
1534 | /* If we're looking at a constant expression, just push its value. */ | |
1535 | { | |
1536 | struct value *v = maybe_const_expr (pc); | |
c5aa993b | 1537 | |
c906108c SS |
1538 | if (v) |
1539 | { | |
1540 | ax_const_l (ax, value_as_long (v)); | |
1541 | value->kind = axs_rvalue; | |
1542 | value->type = check_typedef (VALUE_TYPE (v)); | |
1543 | return; | |
1544 | } | |
1545 | } | |
1546 | ||
1547 | /* Otherwise, go ahead and generate code for it. */ | |
1548 | switch (op) | |
1549 | { | |
1550 | /* Binary arithmetic operators. */ | |
1551 | case BINOP_ADD: | |
1552 | case BINOP_SUB: | |
1553 | case BINOP_MUL: | |
1554 | case BINOP_DIV: | |
1555 | case BINOP_REM: | |
1556 | case BINOP_SUBSCRIPT: | |
1557 | case BINOP_BITWISE_AND: | |
1558 | case BINOP_BITWISE_IOR: | |
1559 | case BINOP_BITWISE_XOR: | |
1560 | (*pc)++; | |
1561 | gen_expr (pc, ax, &value1); | |
1562 | gen_usual_unary (ax, &value1); | |
1563 | gen_expr (pc, ax, &value2); | |
1564 | gen_usual_unary (ax, &value2); | |
1565 | gen_usual_arithmetic (ax, &value1, &value2); | |
1566 | switch (op) | |
1567 | { | |
1568 | case BINOP_ADD: | |
1569 | gen_add (ax, value, &value1, &value2, "addition"); | |
1570 | break; | |
1571 | case BINOP_SUB: | |
1572 | gen_sub (ax, value, &value1, &value2); | |
1573 | break; | |
1574 | case BINOP_MUL: | |
1575 | gen_binop (ax, value, &value1, &value2, | |
1576 | aop_mul, aop_mul, 1, "multiplication"); | |
1577 | break; | |
1578 | case BINOP_DIV: | |
1579 | gen_binop (ax, value, &value1, &value2, | |
1580 | aop_div_signed, aop_div_unsigned, 1, "division"); | |
1581 | break; | |
1582 | case BINOP_REM: | |
1583 | gen_binop (ax, value, &value1, &value2, | |
1584 | aop_rem_signed, aop_rem_unsigned, 1, "remainder"); | |
1585 | break; | |
1586 | case BINOP_SUBSCRIPT: | |
1587 | gen_add (ax, value, &value1, &value2, "array subscripting"); | |
1588 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1589 | error ("Illegal combination of types in array subscripting."); | |
1590 | gen_deref (ax, value); | |
1591 | break; | |
1592 | case BINOP_BITWISE_AND: | |
1593 | gen_binop (ax, value, &value1, &value2, | |
1594 | aop_bit_and, aop_bit_and, 0, "bitwise and"); | |
1595 | break; | |
1596 | ||
1597 | case BINOP_BITWISE_IOR: | |
1598 | gen_binop (ax, value, &value1, &value2, | |
1599 | aop_bit_or, aop_bit_or, 0, "bitwise or"); | |
1600 | break; | |
1601 | ||
1602 | case BINOP_BITWISE_XOR: | |
1603 | gen_binop (ax, value, &value1, &value2, | |
1604 | aop_bit_xor, aop_bit_xor, 0, "bitwise exclusive-or"); | |
1605 | break; | |
1606 | ||
1607 | default: | |
1608 | /* We should only list operators in the outer case statement | |
c5aa993b | 1609 | that we actually handle in the inner case statement. */ |
6426a772 | 1610 | internal_error ("ax-gdb.c (gen_expr): op case sets don't match"); |
c906108c SS |
1611 | } |
1612 | break; | |
1613 | ||
1614 | /* Note that we need to be a little subtle about generating code | |
c5aa993b JM |
1615 | for comma. In C, we can do some optimizations here because |
1616 | we know the left operand is only being evaluated for effect. | |
1617 | However, if the tracing kludge is in effect, then we always | |
1618 | need to evaluate the left hand side fully, so that all the | |
1619 | variables it mentions get traced. */ | |
c906108c SS |
1620 | case BINOP_COMMA: |
1621 | (*pc)++; | |
1622 | gen_expr (pc, ax, &value1); | |
1623 | /* Don't just dispose of the left operand. We might be tracing, | |
c5aa993b JM |
1624 | in which case we want to emit code to trace it if it's an |
1625 | lvalue. */ | |
c906108c SS |
1626 | gen_traced_pop (ax, &value1); |
1627 | gen_expr (pc, ax, value); | |
1628 | /* It's the consumer's responsibility to trace the right operand. */ | |
1629 | break; | |
c5aa993b | 1630 | |
c906108c SS |
1631 | case OP_LONG: /* some integer constant */ |
1632 | { | |
1633 | struct type *type = (*pc)[1].type; | |
1634 | LONGEST k = (*pc)[2].longconst; | |
1635 | (*pc) += 4; | |
1636 | gen_int_literal (ax, value, k, type); | |
1637 | } | |
c5aa993b | 1638 | break; |
c906108c SS |
1639 | |
1640 | case OP_VAR_VALUE: | |
1641 | gen_var_ref (ax, value, (*pc)[2].symbol); | |
1642 | (*pc) += 4; | |
1643 | break; | |
1644 | ||
1645 | case OP_REGISTER: | |
1646 | { | |
1647 | int reg = (int) (*pc)[1].longconst; | |
1648 | (*pc) += 3; | |
1649 | value->kind = axs_lvalue_register; | |
1650 | value->u.reg = reg; | |
1651 | value->type = REGISTER_VIRTUAL_TYPE (reg); | |
1652 | } | |
c5aa993b | 1653 | break; |
c906108c SS |
1654 | |
1655 | case OP_INTERNALVAR: | |
1656 | error ("GDB agent expressions cannot use convenience variables."); | |
1657 | ||
c5aa993b | 1658 | /* Weirdo operator: see comments for gen_repeat for details. */ |
c906108c SS |
1659 | case BINOP_REPEAT: |
1660 | /* Note that gen_repeat handles its own argument evaluation. */ | |
1661 | (*pc)++; | |
1662 | gen_repeat (pc, ax, value); | |
1663 | break; | |
1664 | ||
1665 | case UNOP_CAST: | |
1666 | { | |
1667 | struct type *type = (*pc)[1].type; | |
1668 | (*pc) += 3; | |
1669 | gen_expr (pc, ax, value); | |
1670 | gen_cast (ax, value, type); | |
1671 | } | |
c5aa993b | 1672 | break; |
c906108c SS |
1673 | |
1674 | case UNOP_MEMVAL: | |
1675 | { | |
1676 | struct type *type = check_typedef ((*pc)[1].type); | |
1677 | (*pc) += 3; | |
1678 | gen_expr (pc, ax, value); | |
1679 | /* I'm not sure I understand UNOP_MEMVAL entirely. I think | |
1680 | it's just a hack for dealing with minsyms; you take some | |
1681 | integer constant, pretend it's the address of an lvalue of | |
1682 | the given type, and dereference it. */ | |
1683 | if (value->kind != axs_rvalue) | |
1684 | /* This would be weird. */ | |
6426a772 | 1685 | internal_error ("ax-gdb.c (gen_expr): OP_MEMVAL operand isn't an rvalue???"); |
c906108c SS |
1686 | value->type = type; |
1687 | value->kind = axs_lvalue_memory; | |
1688 | } | |
c5aa993b | 1689 | break; |
c906108c SS |
1690 | |
1691 | case UNOP_NEG: | |
1692 | (*pc)++; | |
1693 | /* -FOO is equivalent to 0 - FOO. */ | |
1694 | gen_int_literal (ax, &value1, (LONGEST) 0, builtin_type_int); | |
c5aa993b | 1695 | gen_usual_unary (ax, &value1); /* shouldn't do much */ |
c906108c SS |
1696 | gen_expr (pc, ax, &value2); |
1697 | gen_usual_unary (ax, &value2); | |
1698 | gen_usual_arithmetic (ax, &value1, &value2); | |
1699 | gen_sub (ax, value, &value1, &value2); | |
1700 | break; | |
1701 | ||
1702 | case UNOP_LOGICAL_NOT: | |
1703 | (*pc)++; | |
1704 | gen_expr (pc, ax, value); | |
1705 | gen_logical_not (ax, value); | |
1706 | break; | |
1707 | ||
1708 | case UNOP_COMPLEMENT: | |
1709 | (*pc)++; | |
1710 | gen_expr (pc, ax, value); | |
1711 | gen_complement (ax, value); | |
1712 | break; | |
1713 | ||
1714 | case UNOP_IND: | |
1715 | (*pc)++; | |
1716 | gen_expr (pc, ax, value); | |
1717 | gen_usual_unary (ax, value); | |
1718 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1719 | error ("Argument of unary `*' is not a pointer."); | |
1720 | gen_deref (ax, value); | |
1721 | break; | |
1722 | ||
1723 | case UNOP_ADDR: | |
1724 | (*pc)++; | |
1725 | gen_expr (pc, ax, value); | |
1726 | gen_address_of (ax, value); | |
1727 | break; | |
1728 | ||
1729 | case UNOP_SIZEOF: | |
1730 | (*pc)++; | |
1731 | /* Notice that gen_sizeof handles its own operand, unlike most | |
c5aa993b JM |
1732 | of the other unary operator functions. This is because we |
1733 | have to throw away the code we generate. */ | |
c906108c SS |
1734 | gen_sizeof (pc, ax, value); |
1735 | break; | |
1736 | ||
1737 | case STRUCTOP_STRUCT: | |
1738 | case STRUCTOP_PTR: | |
1739 | { | |
1740 | int length = (*pc)[1].longconst; | |
1741 | char *name = &(*pc)[2].string; | |
1742 | ||
1743 | (*pc) += 4 + BYTES_TO_EXP_ELEM (length + 1); | |
1744 | gen_expr (pc, ax, value); | |
1745 | if (op == STRUCTOP_STRUCT) | |
1746 | gen_struct_ref (ax, value, name, ".", "structure or union"); | |
1747 | else if (op == STRUCTOP_PTR) | |
1748 | gen_struct_ref (ax, value, name, "->", | |
1749 | "pointer to a structure or union"); | |
1750 | else | |
1751 | /* If this `if' chain doesn't handle it, then the case list | |
c5aa993b | 1752 | shouldn't mention it, and we shouldn't be here. */ |
6426a772 | 1753 | internal_error ("ax-gdb.c (gen_expr): unhandled struct case"); |
c906108c | 1754 | } |
c5aa993b | 1755 | break; |
c906108c SS |
1756 | |
1757 | case OP_TYPE: | |
1758 | error ("Attempt to use a type name as an expression."); | |
1759 | ||
1760 | default: | |
1761 | error ("Unsupported operator in expression."); | |
1762 | } | |
1763 | } | |
c906108c | 1764 | \f |
c5aa993b JM |
1765 | |
1766 | ||
c906108c SS |
1767 | /* Generating bytecode from GDB expressions: driver */ |
1768 | ||
1769 | /* Given a GDB expression EXPR, produce a string of agent bytecode | |
1770 | which computes its value. Return the agent expression, and set | |
1771 | *VALUE to describe its type, and whether it's an lvalue or rvalue. */ | |
1772 | struct agent_expr * | |
1773 | expr_to_agent (expr, value) | |
1774 | struct expression *expr; | |
1775 | struct axs_value *value; | |
1776 | { | |
1777 | struct cleanup *old_chain = 0; | |
6426a772 | 1778 | struct agent_expr *ax = new_agent_expr (0); |
c906108c SS |
1779 | union exp_element *pc; |
1780 | ||
f23d52e0 | 1781 | old_chain = make_cleanup_free_agent_expr (ax); |
c906108c SS |
1782 | |
1783 | pc = expr->elts; | |
1784 | trace_kludge = 0; | |
1785 | gen_expr (&pc, ax, value); | |
1786 | ||
1787 | /* We have successfully built the agent expr, so cancel the cleanup | |
1788 | request. If we add more cleanups that we always want done, this | |
1789 | will have to get more complicated. */ | |
1790 | discard_cleanups (old_chain); | |
1791 | return ax; | |
1792 | } | |
1793 | ||
1794 | ||
6426a772 | 1795 | #if 0 /* not used */ |
c906108c SS |
1796 | /* Given a GDB expression EXPR denoting an lvalue in memory, produce a |
1797 | string of agent bytecode which will leave its address and size on | |
1798 | the top of stack. Return the agent expression. | |
1799 | ||
1800 | Not sure this function is useful at all. */ | |
1801 | struct agent_expr * | |
1802 | expr_to_address_and_size (expr) | |
1803 | struct expression *expr; | |
1804 | { | |
1805 | struct axs_value value; | |
1806 | struct agent_expr *ax = expr_to_agent (expr, &value); | |
1807 | ||
1808 | /* Complain if the result is not a memory lvalue. */ | |
1809 | if (value.kind != axs_lvalue_memory) | |
1810 | { | |
1811 | free_agent_expr (ax); | |
1812 | error ("Expression does not denote an object in memory."); | |
1813 | } | |
1814 | ||
1815 | /* Push the object's size on the stack. */ | |
1816 | ax_const_l (ax, TYPE_LENGTH (value.type)); | |
1817 | ||
1818 | return ax; | |
1819 | } | |
6426a772 | 1820 | #endif |
c906108c SS |
1821 | |
1822 | /* Given a GDB expression EXPR, return bytecode to trace its value. | |
1823 | The result will use the `trace' and `trace_quick' bytecodes to | |
1824 | record the value of all memory touched by the expression. The | |
1825 | caller can then use the ax_reqs function to discover which | |
1826 | registers it relies upon. */ | |
1827 | struct agent_expr * | |
1828 | gen_trace_for_expr (scope, expr) | |
1829 | CORE_ADDR scope; | |
1830 | struct expression *expr; | |
1831 | { | |
1832 | struct cleanup *old_chain = 0; | |
1833 | struct agent_expr *ax = new_agent_expr (scope); | |
1834 | union exp_element *pc; | |
1835 | struct axs_value value; | |
1836 | ||
f23d52e0 | 1837 | old_chain = make_cleanup_free_agent_expr (ax); |
c906108c SS |
1838 | |
1839 | pc = expr->elts; | |
1840 | trace_kludge = 1; | |
1841 | gen_expr (&pc, ax, &value); | |
1842 | ||
1843 | /* Make sure we record the final object, and get rid of it. */ | |
1844 | gen_traced_pop (ax, &value); | |
1845 | ||
1846 | /* Oh, and terminate. */ | |
1847 | ax_simple (ax, aop_end); | |
1848 | ||
1849 | /* We have successfully built the agent expr, so cancel the cleanup | |
1850 | request. If we add more cleanups that we always want done, this | |
1851 | will have to get more complicated. */ | |
1852 | discard_cleanups (old_chain); | |
1853 | return ax; | |
1854 | } | |
c5aa993b | 1855 | \f |
c906108c SS |
1856 | |
1857 | ||
c906108c SS |
1858 | /* The "agent" command, for testing: compile and disassemble an expression. */ |
1859 | ||
1860 | static void | |
1861 | print_axs_value (f, value) | |
d9fcf2fb | 1862 | struct ui_file *f; |
c906108c SS |
1863 | struct axs_value *value; |
1864 | { | |
1865 | switch (value->kind) | |
1866 | { | |
1867 | case axs_rvalue: | |
1868 | fputs_filtered ("rvalue", f); | |
1869 | break; | |
1870 | ||
1871 | case axs_lvalue_memory: | |
1872 | fputs_filtered ("memory lvalue", f); | |
1873 | break; | |
1874 | ||
1875 | case axs_lvalue_register: | |
1876 | fprintf_filtered (f, "register %d lvalue", value->u.reg); | |
1877 | break; | |
1878 | } | |
1879 | ||
1880 | fputs_filtered (" : ", f); | |
1881 | type_print (value->type, "", f, -1); | |
1882 | } | |
1883 | ||
1884 | ||
1885 | static void | |
1886 | agent_command (exp, from_tty) | |
1887 | char *exp; | |
1888 | int from_tty; | |
1889 | { | |
1890 | struct cleanup *old_chain = 0; | |
1891 | struct expression *expr; | |
1892 | struct agent_expr *agent; | |
6426a772 | 1893 | struct frame_info *fi = get_current_frame (); /* need current scope */ |
c906108c SS |
1894 | |
1895 | /* We don't deal with overlay debugging at the moment. We need to | |
1896 | think more carefully about this. If you copy this code into | |
1897 | another command, change the error message; the user shouldn't | |
1898 | have to know anything about agent expressions. */ | |
1899 | if (overlay_debugging) | |
1900 | error ("GDB can't do agent expression translation with overlays."); | |
1901 | ||
1902 | if (exp == 0) | |
1903 | error_no_arg ("expression to translate"); | |
c5aa993b | 1904 | |
c906108c | 1905 | expr = parse_expression (exp); |
c13c43fd | 1906 | old_chain = make_cleanup (free_current_contents, &expr); |
c906108c | 1907 | agent = gen_trace_for_expr (fi->pc, expr); |
f23d52e0 | 1908 | make_cleanup_free_agent_expr (agent); |
c906108c | 1909 | ax_print (gdb_stdout, agent); |
085dd6e6 JM |
1910 | |
1911 | /* It would be nice to call ax_reqs here to gather some general info | |
1912 | about the expression, and then print out the result. */ | |
c906108c SS |
1913 | |
1914 | do_cleanups (old_chain); | |
1915 | dont_repeat (); | |
1916 | } | |
c906108c | 1917 | \f |
c5aa993b | 1918 | |
c906108c SS |
1919 | /* Initialization code. */ |
1920 | ||
a14ed312 | 1921 | void _initialize_ax_gdb (void); |
c906108c SS |
1922 | void |
1923 | _initialize_ax_gdb () | |
1924 | { | |
c906108c SS |
1925 | add_cmd ("agent", class_maintenance, agent_command, |
1926 | "Translate an expression into remote agent bytecode.", | |
1927 | &maintenancelist); | |
1928 | } |