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[deliverable/binutils-gdb.git] / gdb / go-lang.c
1 /* Go language support routines for GDB, the GNU debugger.
2
3 Copyright (C) 2012-2020 Free Software Foundation, Inc.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20 /* TODO:
21 - split stacks
22 - printing of native types
23 - goroutines
24 - lots more
25 - gccgo mangling needs redoing
26 It's too hard, for example, to know whether one is looking at a mangled
27 Go symbol or not, and their are ambiguities, e.g., the demangler may
28 get passed *any* symbol, including symbols from other languages
29 and including symbols that are already demangled.
30 One thought is to at least add an _G prefix.
31 - 6g mangling isn't supported yet
32 */
33
34 #include "defs.h"
35 #include "gdb_obstack.h"
36 #include "block.h"
37 #include "symtab.h"
38 #include "language.h"
39 #include "varobj.h"
40 #include "go-lang.h"
41 #include "c-lang.h"
42 #include "parser-defs.h"
43 #include "gdbarch.h"
44
45 #include <ctype.h>
46
47 /* The main function in the main package. */
48 static const char GO_MAIN_MAIN[] = "main.main";
49
50 /* Function returning the special symbol name used by Go for the main
51 procedure in the main program if it is found in minimal symbol list.
52 This function tries to find minimal symbols so that it finds them even
53 if the program was compiled without debugging information. */
54
55 const char *
56 go_main_name (void)
57 {
58 struct bound_minimal_symbol msym;
59
60 msym = lookup_minimal_symbol (GO_MAIN_MAIN, NULL, NULL);
61 if (msym.minsym != NULL)
62 return GO_MAIN_MAIN;
63
64 /* No known entry procedure found, the main program is probably not Go. */
65 return NULL;
66 }
67
68 /* Return non-zero if TYPE is a gccgo string.
69 We assume CHECK_TYPEDEF has already been done. */
70
71 static int
72 gccgo_string_p (struct type *type)
73 {
74 /* gccgo strings don't necessarily have a name we can use. */
75
76 if (type->num_fields () == 2)
77 {
78 struct type *type0 = type->field (0).type ();
79 struct type *type1 = type->field (1).type ();
80
81 type0 = check_typedef (type0);
82 type1 = check_typedef (type1);
83
84 if (type0->code () == TYPE_CODE_PTR
85 && strcmp (TYPE_FIELD_NAME (type, 0), "__data") == 0
86 && type1->code () == TYPE_CODE_INT
87 && strcmp (TYPE_FIELD_NAME (type, 1), "__length") == 0)
88 {
89 struct type *target_type = TYPE_TARGET_TYPE (type0);
90
91 target_type = check_typedef (target_type);
92
93 if (target_type->code () == TYPE_CODE_INT
94 && TYPE_LENGTH (target_type) == 1
95 && strcmp (target_type->name (), "uint8") == 0)
96 return 1;
97 }
98 }
99
100 return 0;
101 }
102
103 /* Return non-zero if TYPE is a 6g string.
104 We assume CHECK_TYPEDEF has already been done. */
105
106 static int
107 sixg_string_p (struct type *type)
108 {
109 if (type->num_fields () == 2
110 && type->name () != NULL
111 && strcmp (type->name (), "string") == 0)
112 return 1;
113
114 return 0;
115 }
116
117 /* Classify the kind of Go object that TYPE is.
118 TYPE is a TYPE_CODE_STRUCT, used to represent a Go object. */
119
120 enum go_type
121 go_classify_struct_type (struct type *type)
122 {
123 type = check_typedef (type);
124
125 /* Recognize strings as they're useful to be able to print without
126 pretty-printers. */
127 if (gccgo_string_p (type)
128 || sixg_string_p (type))
129 return GO_TYPE_STRING;
130
131 return GO_TYPE_NONE;
132 }
133
134 /* Subroutine of unpack_mangled_go_symbol to simplify it.
135 Given "[foo.]bar.baz", store "bar" in *PACKAGEP and "baz" in *OBJECTP.
136 We stomp on the last '.' to nul-terminate "bar".
137 The caller is responsible for memory management. */
138
139 static void
140 unpack_package_and_object (char *buf,
141 const char **packagep, const char **objectp)
142 {
143 char *last_dot;
144
145 last_dot = strrchr (buf, '.');
146 gdb_assert (last_dot != NULL);
147 *objectp = last_dot + 1;
148 *last_dot = '\0';
149 last_dot = strrchr (buf, '.');
150 if (last_dot != NULL)
151 *packagep = last_dot + 1;
152 else
153 *packagep = buf;
154 }
155
156 /* Given a mangled Go symbol, find its package name, object name, and
157 method type (if present).
158 E.g., for "libgo_net.textproto.String.N33_libgo_net.textproto.ProtocolError"
159 *PACKAGEP = "textproto"
160 *OBJECTP = "String"
161 *METHOD_TYPE_PACKAGEP = "textproto"
162 *METHOD_TYPE_OBJECTP = "ProtocolError"
163
164 Space for the resulting strings is malloc'd in one buffer.
165 PACKAGEP,OBJECTP,METHOD_TYPE* will (typically) point into this buffer.
166 [There are a few exceptions, but the caller is still responsible for
167 freeing the resulting pointer.]
168 A pointer to this buffer is returned, or NULL if symbol isn't a
169 mangled Go symbol.
170 The caller is responsible for freeing the result.
171
172 *METHOD_TYPE_IS_POINTERP is set to a boolean indicating if
173 the method type is a pointer.
174
175 There may be value in returning the outer container,
176 i.e., "net" in the above example, but for now it's not needed.
177 Plus it's currently not straightforward to compute,
178 it comes from -fgo-prefix, and there's no algorithm to compute it.
179
180 If we ever need to unpack the method type, this routine should work
181 for that too. */
182
183 static char *
184 unpack_mangled_go_symbol (const char *mangled_name,
185 const char **packagep,
186 const char **objectp,
187 const char **method_type_packagep,
188 const char **method_type_objectp,
189 int *method_type_is_pointerp)
190 {
191 char *buf;
192 char *p;
193 int len = strlen (mangled_name);
194 /* Pointer to last digit in "N<digit(s)>_". */
195 char *saw_digit;
196 /* Pointer to "N" if valid "N<digit(s)>_" found. */
197 char *method_type;
198 /* Pointer to the first '.'. */
199 const char *first_dot;
200 /* Pointer to the last '.'. */
201 const char *last_dot;
202 /* Non-zero if we saw a pointer indicator. */
203 int saw_pointer;
204
205 *packagep = *objectp = NULL;
206 *method_type_packagep = *method_type_objectp = NULL;
207 *method_type_is_pointerp = 0;
208
209 /* main.init is mangled specially. */
210 if (strcmp (mangled_name, "__go_init_main") == 0)
211 {
212 char *package = xstrdup ("main");
213
214 *packagep = package;
215 *objectp = "init";
216 return package;
217 }
218
219 /* main.main is mangled specially (missing prefix). */
220 if (strcmp (mangled_name, "main.main") == 0)
221 {
222 char *package = xstrdup ("main");
223
224 *packagep = package;
225 *objectp = "main";
226 return package;
227 }
228
229 /* We may get passed, e.g., "main.T.Foo", which is *not* mangled.
230 Alas it looks exactly like "prefix.package.object."
231 To cope for now we only recognize the following prefixes:
232
233 go: the default
234 libgo_.*: used by gccgo's runtime
235
236 Thus we don't support -fgo-prefix (except as used by the runtime). */
237 if (!startswith (mangled_name, "go.")
238 && !startswith (mangled_name, "libgo_"))
239 return NULL;
240
241 /* Quick check for whether a search may be fruitful. */
242 /* Ignore anything with @plt, etc. in it. */
243 if (strchr (mangled_name, '@') != NULL)
244 return NULL;
245 /* It must have at least two dots. */
246 first_dot = strchr (mangled_name, '.');
247 if (first_dot == NULL)
248 return NULL;
249 /* Treat "foo.bar" as unmangled. It can collide with lots of other
250 languages and it's not clear what the consequences are.
251 And except for main.main, all gccgo symbols are at least
252 prefix.package.object. */
253 last_dot = strrchr (mangled_name, '.');
254 if (last_dot == first_dot)
255 return NULL;
256
257 /* More quick checks. */
258 if (last_dot[1] == '\0' /* foo. */
259 || last_dot[-1] == '.') /* foo..bar */
260 return NULL;
261
262 /* At this point we've decided we have a mangled Go symbol. */
263
264 buf = xstrdup (mangled_name);
265
266 /* Search backwards looking for "N<digit(s)>". */
267 p = buf + len;
268 saw_digit = method_type = NULL;
269 saw_pointer = 0;
270 while (p > buf)
271 {
272 int current = *(const unsigned char *) --p;
273 int current_is_digit = isdigit (current);
274
275 if (saw_digit)
276 {
277 if (current_is_digit)
278 continue;
279 if (current == 'N'
280 && ((p > buf && p[-1] == '.')
281 || (p > buf + 1 && p[-1] == 'p' && p[-2] == '.')))
282 {
283 if (atoi (p + 1) == strlen (saw_digit + 2))
284 {
285 if (p[-1] == '.')
286 method_type = p - 1;
287 else
288 {
289 gdb_assert (p[-1] == 'p');
290 saw_pointer = 1;
291 method_type = p - 2;
292 }
293 break;
294 }
295 }
296 /* Not what we're looking for, reset and keep looking. */
297 saw_digit = NULL;
298 saw_pointer = 0;
299 continue;
300 }
301 if (current_is_digit && p[1] == '_')
302 {
303 /* Possible start of method "this" [sic] type. */
304 saw_digit = p;
305 continue;
306 }
307 }
308
309 if (method_type != NULL
310 /* Ensure not something like "..foo". */
311 && (method_type > buf && method_type[-1] != '.'))
312 {
313 unpack_package_and_object (saw_digit + 2,
314 method_type_packagep, method_type_objectp);
315 *method_type = '\0';
316 *method_type_is_pointerp = saw_pointer;
317 }
318
319 unpack_package_and_object (buf, packagep, objectp);
320 return buf;
321 }
322
323 /* Implements the la_demangle language_defn routine for language Go.
324
325 N.B. This may get passed *any* symbol, including symbols from other
326 languages and including symbols that are already demangled.
327 Both of these situations are kinda unfortunate, but that's how things
328 are today.
329
330 N.B. This currently only supports gccgo's mangling.
331
332 N.B. gccgo's mangling needs, I think, changing.
333 This demangler can't work in all situations,
334 thus not too much effort is currently put into it. */
335
336 char *
337 go_demangle (const char *mangled_name, int options)
338 {
339 struct obstack tempbuf;
340 char *result;
341 char *name_buf;
342 const char *package_name;
343 const char *object_name;
344 const char *method_type_package_name;
345 const char *method_type_object_name;
346 int method_type_is_pointer;
347
348 if (mangled_name == NULL)
349 return NULL;
350
351 name_buf = unpack_mangled_go_symbol (mangled_name,
352 &package_name, &object_name,
353 &method_type_package_name,
354 &method_type_object_name,
355 &method_type_is_pointer);
356 if (name_buf == NULL)
357 return NULL;
358
359 obstack_init (&tempbuf);
360
361 /* Print methods as they appear in "method expressions". */
362 if (method_type_package_name != NULL)
363 {
364 /* FIXME: Seems like we should include package_name here somewhere. */
365 if (method_type_is_pointer)
366 obstack_grow_str (&tempbuf, "(*");
367 obstack_grow_str (&tempbuf, method_type_package_name);
368 obstack_grow_str (&tempbuf, ".");
369 obstack_grow_str (&tempbuf, method_type_object_name);
370 if (method_type_is_pointer)
371 obstack_grow_str (&tempbuf, ")");
372 obstack_grow_str (&tempbuf, ".");
373 obstack_grow_str (&tempbuf, object_name);
374 }
375 else
376 {
377 obstack_grow_str (&tempbuf, package_name);
378 obstack_grow_str (&tempbuf, ".");
379 obstack_grow_str (&tempbuf, object_name);
380 }
381 obstack_grow_str0 (&tempbuf, "");
382
383 result = xstrdup ((const char *) obstack_finish (&tempbuf));
384 obstack_free (&tempbuf, NULL);
385 xfree (name_buf);
386 return result;
387 }
388
389 /* Given a Go symbol, return its package or NULL if unknown.
390 Space for the result is malloc'd, caller must free. */
391
392 char *
393 go_symbol_package_name (const struct symbol *sym)
394 {
395 const char *mangled_name = sym->linkage_name ();
396 const char *package_name;
397 const char *object_name;
398 const char *method_type_package_name;
399 const char *method_type_object_name;
400 int method_type_is_pointer;
401 char *name_buf;
402 char *result;
403
404 gdb_assert (sym->language () == language_go);
405 name_buf = unpack_mangled_go_symbol (mangled_name,
406 &package_name, &object_name,
407 &method_type_package_name,
408 &method_type_object_name,
409 &method_type_is_pointer);
410 /* Some Go symbols don't have mangled form we interpret (yet). */
411 if (name_buf == NULL)
412 return NULL;
413 result = xstrdup (package_name);
414 xfree (name_buf);
415 return result;
416 }
417
418 /* Return the package that BLOCK is in, or NULL if there isn't one.
419 Space for the result is malloc'd, caller must free. */
420
421 char *
422 go_block_package_name (const struct block *block)
423 {
424 while (block != NULL)
425 {
426 struct symbol *function = BLOCK_FUNCTION (block);
427
428 if (function != NULL)
429 {
430 char *package_name = go_symbol_package_name (function);
431
432 if (package_name != NULL)
433 return package_name;
434
435 /* Stop looking if we find a function without a package name.
436 We're most likely outside of Go and thus the concept of the
437 "current" package is gone. */
438 return NULL;
439 }
440
441 block = BLOCK_SUPERBLOCK (block);
442 }
443
444 return NULL;
445 }
446
447 /* Table mapping opcodes into strings for printing operators
448 and precedences of the operators.
449 TODO(dje): &^ ? */
450
451 static const struct op_print go_op_print_tab[] =
452 {
453 {",", BINOP_COMMA, PREC_COMMA, 0},
454 {"=", BINOP_ASSIGN, PREC_ASSIGN, 1},
455 {"||", BINOP_LOGICAL_OR, PREC_LOGICAL_OR, 0},
456 {"&&", BINOP_LOGICAL_AND, PREC_LOGICAL_AND, 0},
457 {"|", BINOP_BITWISE_IOR, PREC_BITWISE_IOR, 0},
458 {"^", BINOP_BITWISE_XOR, PREC_BITWISE_XOR, 0},
459 {"&", BINOP_BITWISE_AND, PREC_BITWISE_AND, 0},
460 {"==", BINOP_EQUAL, PREC_EQUAL, 0},
461 {"!=", BINOP_NOTEQUAL, PREC_EQUAL, 0},
462 {"<=", BINOP_LEQ, PREC_ORDER, 0},
463 {">=", BINOP_GEQ, PREC_ORDER, 0},
464 {">", BINOP_GTR, PREC_ORDER, 0},
465 {"<", BINOP_LESS, PREC_ORDER, 0},
466 {">>", BINOP_RSH, PREC_SHIFT, 0},
467 {"<<", BINOP_LSH, PREC_SHIFT, 0},
468 {"+", BINOP_ADD, PREC_ADD, 0},
469 {"-", BINOP_SUB, PREC_ADD, 0},
470 {"*", BINOP_MUL, PREC_MUL, 0},
471 {"/", BINOP_DIV, PREC_MUL, 0},
472 {"%", BINOP_REM, PREC_MUL, 0},
473 {"@", BINOP_REPEAT, PREC_REPEAT, 0},
474 {"-", UNOP_NEG, PREC_PREFIX, 0},
475 {"!", UNOP_LOGICAL_NOT, PREC_PREFIX, 0},
476 {"^", UNOP_COMPLEMENT, PREC_PREFIX, 0},
477 {"*", UNOP_IND, PREC_PREFIX, 0},
478 {"&", UNOP_ADDR, PREC_PREFIX, 0},
479 {"unsafe.Sizeof ", UNOP_SIZEOF, PREC_PREFIX, 0},
480 {"++", UNOP_POSTINCREMENT, PREC_SUFFIX, 0},
481 {"--", UNOP_POSTDECREMENT, PREC_SUFFIX, 0},
482 {NULL, OP_NULL, PREC_SUFFIX, 0}
483 };
484
485 /* Class representing the Go language. */
486
487 class go_language : public language_defn
488 {
489 public:
490 go_language ()
491 : language_defn (language_go)
492 { /* Nothing. */ }
493
494 /* See language.h. */
495
496 const char *name () const override
497 { return "go"; }
498
499 /* See language.h. */
500
501 const char *natural_name () const override
502 { return "Go"; }
503
504 /* See language.h. */
505 void language_arch_info (struct gdbarch *gdbarch,
506 struct language_arch_info *lai) const override
507 {
508 const struct builtin_go_type *builtin = builtin_go_type (gdbarch);
509
510 /* Helper function to allow shorter lines below. */
511 auto add = [&] (struct type * t) -> struct type *
512 {
513 lai->add_primitive_type (t);
514 return t;
515 };
516
517 add (builtin->builtin_void);
518 add (builtin->builtin_char);
519 add (builtin->builtin_bool);
520 add (builtin->builtin_int);
521 add (builtin->builtin_uint);
522 add (builtin->builtin_uintptr);
523 add (builtin->builtin_int8);
524 add (builtin->builtin_int16);
525 add (builtin->builtin_int32);
526 add (builtin->builtin_int64);
527 add (builtin->builtin_uint8);
528 add (builtin->builtin_uint16);
529 add (builtin->builtin_uint32);
530 add (builtin->builtin_uint64);
531 add (builtin->builtin_float32);
532 add (builtin->builtin_float64);
533 add (builtin->builtin_complex64);
534 add (builtin->builtin_complex128);
535
536 lai->set_string_char_type (builtin->builtin_char);
537 lai->set_bool_type (builtin->builtin_bool, "bool");
538 }
539
540 /* See language.h. */
541 bool sniff_from_mangled_name (const char *mangled,
542 char **demangled) const override
543 {
544 *demangled = go_demangle (mangled, 0);
545 return *demangled != NULL;
546 }
547
548 /* See language.h. */
549
550 char *demangle_symbol (const char *mangled, int options) const override
551 {
552 return go_demangle (mangled, options);
553 }
554
555 /* See language.h. */
556
557 void print_type (struct type *type, const char *varstring,
558 struct ui_file *stream, int show, int level,
559 const struct type_print_options *flags) const override
560 {
561 go_print_type (type, varstring, stream, show, level, flags);
562 }
563
564 /* See language.h. */
565
566 void value_print_inner
567 (struct value *val, struct ui_file *stream, int recurse,
568 const struct value_print_options *options) const override
569 {
570 return go_value_print_inner (val, stream, recurse, options);
571 }
572
573 /* See language.h. */
574
575 int parser (struct parser_state *ps) const override
576 {
577 return go_parse (ps);
578 }
579
580 /* See language.h. */
581
582 bool is_string_type_p (struct type *type) const override
583 {
584 type = check_typedef (type);
585 return (type->code () == TYPE_CODE_STRUCT
586 && go_classify_struct_type (type) == GO_TYPE_STRING);
587 }
588
589 /* See language.h. */
590
591 bool store_sym_names_in_linkage_form_p () const override
592 { return true; }
593
594 /* See language.h. */
595
596 const struct exp_descriptor *expression_ops () const override
597 { return &exp_descriptor_c; }
598
599 /* See language.h. */
600
601 const struct op_print *opcode_print_table () const override
602 { return go_op_print_tab; }
603 };
604
605 /* Single instance of the Go language class. */
606
607 static go_language go_language_defn;
608
609 static void *
610 build_go_types (struct gdbarch *gdbarch)
611 {
612 struct builtin_go_type *builtin_go_type
613 = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct builtin_go_type);
614
615 builtin_go_type->builtin_void
616 = arch_type (gdbarch, TYPE_CODE_VOID, TARGET_CHAR_BIT, "void");
617 builtin_go_type->builtin_char
618 = arch_character_type (gdbarch, 8, 1, "char");
619 builtin_go_type->builtin_bool
620 = arch_boolean_type (gdbarch, 8, 0, "bool");
621 builtin_go_type->builtin_int
622 = arch_integer_type (gdbarch, gdbarch_int_bit (gdbarch), 0, "int");
623 builtin_go_type->builtin_uint
624 = arch_integer_type (gdbarch, gdbarch_int_bit (gdbarch), 1, "uint");
625 builtin_go_type->builtin_uintptr
626 = arch_integer_type (gdbarch, gdbarch_ptr_bit (gdbarch), 1, "uintptr");
627 builtin_go_type->builtin_int8
628 = arch_integer_type (gdbarch, 8, 0, "int8");
629 builtin_go_type->builtin_int16
630 = arch_integer_type (gdbarch, 16, 0, "int16");
631 builtin_go_type->builtin_int32
632 = arch_integer_type (gdbarch, 32, 0, "int32");
633 builtin_go_type->builtin_int64
634 = arch_integer_type (gdbarch, 64, 0, "int64");
635 builtin_go_type->builtin_uint8
636 = arch_integer_type (gdbarch, 8, 1, "uint8");
637 builtin_go_type->builtin_uint16
638 = arch_integer_type (gdbarch, 16, 1, "uint16");
639 builtin_go_type->builtin_uint32
640 = arch_integer_type (gdbarch, 32, 1, "uint32");
641 builtin_go_type->builtin_uint64
642 = arch_integer_type (gdbarch, 64, 1, "uint64");
643 builtin_go_type->builtin_float32
644 = arch_float_type (gdbarch, 32, "float32", floatformats_ieee_single);
645 builtin_go_type->builtin_float64
646 = arch_float_type (gdbarch, 64, "float64", floatformats_ieee_double);
647 builtin_go_type->builtin_complex64
648 = init_complex_type ("complex64", builtin_go_type->builtin_float32);
649 builtin_go_type->builtin_complex128
650 = init_complex_type ("complex128", builtin_go_type->builtin_float64);
651
652 return builtin_go_type;
653 }
654
655 static struct gdbarch_data *go_type_data;
656
657 const struct builtin_go_type *
658 builtin_go_type (struct gdbarch *gdbarch)
659 {
660 return (const struct builtin_go_type *) gdbarch_data (gdbarch, go_type_data);
661 }
662
663 void _initialize_go_language ();
664 void
665 _initialize_go_language ()
666 {
667 go_type_data = gdbarch_data_register_post_init (build_go_types);
668 }
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