2010-11-19 Jan Kratochvil <jan.kratochvil@redhat.com>
[deliverable/binutils-gdb.git] / gdb / lm32-tdep.c
1 /* Target-dependent code for Lattice Mico32 processor, for GDB.
2 Contributed by Jon Beniston <jon@beniston.com>
3
4 Copyright (C) 2009, 2010 Free Software Foundation, Inc.
5
6 This file is part of GDB.
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20
21 #include "defs.h"
22 #include "frame.h"
23 #include "frame-unwind.h"
24 #include "frame-base.h"
25 #include "inferior.h"
26 #include "dis-asm.h"
27 #include "symfile.h"
28 #include "remote.h"
29 #include "gdbcore.h"
30 #include "gdb/sim-lm32.h"
31 #include "gdb/callback.h"
32 #include "gdb/remote-sim.h"
33 #include "sim-regno.h"
34 #include "arch-utils.h"
35 #include "regcache.h"
36 #include "trad-frame.h"
37 #include "reggroups.h"
38 #include "opcodes/lm32-desc.h"
39
40 #include "gdb_string.h"
41
42 /* Macros to extract fields from an instruction. */
43 #define LM32_OPCODE(insn) ((insn >> 26) & 0x3f)
44 #define LM32_REG0(insn) ((insn >> 21) & 0x1f)
45 #define LM32_REG1(insn) ((insn >> 16) & 0x1f)
46 #define LM32_REG2(insn) ((insn >> 11) & 0x1f)
47 #define LM32_IMM16(insn) ((((long)insn & 0xffff) << 16) >> 16)
48
49 struct gdbarch_tdep
50 {
51 /* gdbarch target dependent data here. Currently unused for LM32. */
52 };
53
54 struct lm32_frame_cache
55 {
56 /* The frame's base. Used when constructing a frame ID. */
57 CORE_ADDR base;
58 CORE_ADDR pc;
59 /* Size of frame. */
60 int size;
61 /* Table indicating the location of each and every register. */
62 struct trad_frame_saved_reg *saved_regs;
63 };
64
65 /* Add the available register groups. */
66
67 static void
68 lm32_add_reggroups (struct gdbarch *gdbarch)
69 {
70 reggroup_add (gdbarch, general_reggroup);
71 reggroup_add (gdbarch, all_reggroup);
72 reggroup_add (gdbarch, system_reggroup);
73 }
74
75 /* Return whether a given register is in a given group. */
76
77 static int
78 lm32_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
79 struct reggroup *group)
80 {
81 if (group == general_reggroup)
82 return ((regnum >= SIM_LM32_R0_REGNUM) && (regnum <= SIM_LM32_RA_REGNUM))
83 || (regnum == SIM_LM32_PC_REGNUM);
84 else if (group == system_reggroup)
85 return ((regnum >= SIM_LM32_EA_REGNUM) && (regnum <= SIM_LM32_BA_REGNUM))
86 || ((regnum >= SIM_LM32_EID_REGNUM) && (regnum <= SIM_LM32_IP_REGNUM));
87 return default_register_reggroup_p (gdbarch, regnum, group);
88 }
89
90 /* Return a name that corresponds to the given register number. */
91
92 static const char *
93 lm32_register_name (struct gdbarch *gdbarch, int reg_nr)
94 {
95 static char *register_names[] = {
96 "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
97 "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
98 "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
99 "r24", "r25", "gp", "fp", "sp", "ra", "ea", "ba",
100 "PC", "EID", "EBA", "DEBA", "IE", "IM", "IP"
101 };
102
103 if ((reg_nr < 0) || (reg_nr >= ARRAY_SIZE (register_names)))
104 return NULL;
105 else
106 return register_names[reg_nr];
107 }
108
109 /* Return type of register. */
110
111 static struct type *
112 lm32_register_type (struct gdbarch *gdbarch, int reg_nr)
113 {
114 return builtin_type (gdbarch)->builtin_int32;
115 }
116
117 /* Return non-zero if a register can't be written. */
118
119 static int
120 lm32_cannot_store_register (struct gdbarch *gdbarch, int regno)
121 {
122 return (regno == SIM_LM32_R0_REGNUM) || (regno == SIM_LM32_EID_REGNUM);
123 }
124
125 /* Analyze a function's prologue. */
126
127 static CORE_ADDR
128 lm32_analyze_prologue (struct gdbarch *gdbarch,
129 CORE_ADDR pc, CORE_ADDR limit,
130 struct lm32_frame_cache *info)
131 {
132 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
133 unsigned long instruction;
134
135 /* Keep reading though instructions, until we come across an instruction
136 that isn't likely to be part of the prologue. */
137 info->size = 0;
138 for (; pc < limit; pc += 4)
139 {
140
141 /* Read an instruction. */
142 instruction = read_memory_integer (pc, 4, byte_order);
143
144 if ((LM32_OPCODE (instruction) == OP_SW)
145 && (LM32_REG0 (instruction) == SIM_LM32_SP_REGNUM))
146 {
147 /* Any stack displaced store is likely part of the prologue.
148 Record that the register is being saved, and the offset
149 into the stack. */
150 info->saved_regs[LM32_REG1 (instruction)].addr =
151 LM32_IMM16 (instruction);
152 }
153 else if ((LM32_OPCODE (instruction) == OP_ADDI)
154 && (LM32_REG1 (instruction) == SIM_LM32_SP_REGNUM))
155 {
156 /* An add to the SP is likely to be part of the prologue.
157 Adjust stack size by whatever the instruction adds to the sp. */
158 info->size -= LM32_IMM16 (instruction);
159 }
160 else if ( /* add fp,fp,sp */
161 ((LM32_OPCODE (instruction) == OP_ADD)
162 && (LM32_REG2 (instruction) == SIM_LM32_FP_REGNUM)
163 && (LM32_REG0 (instruction) == SIM_LM32_FP_REGNUM)
164 && (LM32_REG1 (instruction) == SIM_LM32_SP_REGNUM))
165 /* mv fp,imm */
166 || ((LM32_OPCODE (instruction) == OP_ADDI)
167 && (LM32_REG1 (instruction) == SIM_LM32_FP_REGNUM)
168 && (LM32_REG0 (instruction) == SIM_LM32_R0_REGNUM)))
169 {
170 /* Likely to be in the prologue for functions that require
171 a frame pointer. */
172 }
173 else
174 {
175 /* Any other instruction is likely not to be part of the prologue. */
176 break;
177 }
178 }
179
180 return pc;
181 }
182
183 /* Return PC of first non prologue instruction, for the function at the
184 specified address. */
185
186 static CORE_ADDR
187 lm32_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
188 {
189 CORE_ADDR func_addr, limit_pc;
190 struct symtab_and_line sal;
191 struct lm32_frame_cache frame_info;
192 struct trad_frame_saved_reg saved_regs[SIM_LM32_NUM_REGS];
193
194 /* See if we can determine the end of the prologue via the symbol table.
195 If so, then return either PC, or the PC after the prologue, whichever
196 is greater. */
197 if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
198 {
199 CORE_ADDR post_prologue_pc
200 = skip_prologue_using_sal (gdbarch, func_addr);
201 if (post_prologue_pc != 0)
202 return max (pc, post_prologue_pc);
203 }
204
205 /* Can't determine prologue from the symbol table, need to examine
206 instructions. */
207
208 /* Find an upper limit on the function prologue using the debug
209 information. If the debug information could not be used to provide
210 that bound, then use an arbitrary large number as the upper bound. */
211 limit_pc = skip_prologue_using_sal (gdbarch, pc);
212 if (limit_pc == 0)
213 limit_pc = pc + 100; /* Magic. */
214
215 frame_info.saved_regs = saved_regs;
216 return lm32_analyze_prologue (gdbarch, pc, limit_pc, &frame_info);
217 }
218
219 /* Create a breakpoint instruction. */
220
221 static const gdb_byte *
222 lm32_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr,
223 int *lenptr)
224 {
225 static const gdb_byte breakpoint[4] = { OP_RAISE << 2, 0, 0, 2 };
226
227 *lenptr = sizeof (breakpoint);
228 return breakpoint;
229 }
230
231 /* Setup registers and stack for faking a call to a function in the
232 inferior. */
233
234 static CORE_ADDR
235 lm32_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
236 struct regcache *regcache, CORE_ADDR bp_addr,
237 int nargs, struct value **args, CORE_ADDR sp,
238 int struct_return, CORE_ADDR struct_addr)
239 {
240 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
241 int first_arg_reg = SIM_LM32_R1_REGNUM;
242 int num_arg_regs = 8;
243 int i;
244
245 /* Set the return address. */
246 regcache_cooked_write_signed (regcache, SIM_LM32_RA_REGNUM, bp_addr);
247
248 /* If we're returning a large struct, a pointer to the address to
249 store it at is passed as a first hidden parameter. */
250 if (struct_return)
251 {
252 regcache_cooked_write_unsigned (regcache, first_arg_reg, struct_addr);
253 first_arg_reg++;
254 num_arg_regs--;
255 sp -= 4;
256 }
257
258 /* Setup parameters. */
259 for (i = 0; i < nargs; i++)
260 {
261 struct value *arg = args[i];
262 struct type *arg_type = check_typedef (value_type (arg));
263 gdb_byte *contents;
264 int len;
265 int j;
266 int reg;
267 ULONGEST val;
268
269 /* Promote small integer types to int. */
270 switch (TYPE_CODE (arg_type))
271 {
272 case TYPE_CODE_INT:
273 case TYPE_CODE_BOOL:
274 case TYPE_CODE_CHAR:
275 case TYPE_CODE_RANGE:
276 case TYPE_CODE_ENUM:
277 if (TYPE_LENGTH (arg_type) < 4)
278 {
279 arg_type = builtin_type (gdbarch)->builtin_int32;
280 arg = value_cast (arg_type, arg);
281 }
282 break;
283 }
284
285 /* FIXME: Handle structures. */
286
287 contents = (gdb_byte *) value_contents (arg);
288 len = TYPE_LENGTH (arg_type);
289 val = extract_unsigned_integer (contents, len, byte_order);
290
291 /* First num_arg_regs parameters are passed by registers,
292 and the rest are passed on the stack. */
293 if (i < num_arg_regs)
294 regcache_cooked_write_unsigned (regcache, first_arg_reg + i, val);
295 else
296 {
297 write_memory (sp, (void *) &val, len);
298 sp -= 4;
299 }
300 }
301
302 /* Update stack pointer. */
303 regcache_cooked_write_signed (regcache, SIM_LM32_SP_REGNUM, sp);
304
305 /* Return adjusted stack pointer. */
306 return sp;
307 }
308
309 /* Extract return value after calling a function in the inferior. */
310
311 static void
312 lm32_extract_return_value (struct type *type, struct regcache *regcache,
313 gdb_byte *valbuf)
314 {
315 struct gdbarch *gdbarch = get_regcache_arch (regcache);
316 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
317 int offset;
318 ULONGEST l;
319 CORE_ADDR return_buffer;
320
321 if (TYPE_CODE (type) != TYPE_CODE_STRUCT
322 && TYPE_CODE (type) != TYPE_CODE_UNION
323 && TYPE_CODE (type) != TYPE_CODE_ARRAY && TYPE_LENGTH (type) <= 4)
324 {
325 /* Return value is returned in a single register. */
326 regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
327 store_unsigned_integer (valbuf, TYPE_LENGTH (type), byte_order, l);
328 }
329 else if ((TYPE_CODE (type) == TYPE_CODE_INT) && (TYPE_LENGTH (type) == 8))
330 {
331 /* 64-bit values are returned in a register pair. */
332 regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
333 memcpy (valbuf, &l, 4);
334 regcache_cooked_read_unsigned (regcache, SIM_LM32_R2_REGNUM, &l);
335 memcpy (valbuf + 4, &l, 4);
336 }
337 else
338 {
339 /* Aggregate types greater than a single register are returned in memory.
340 FIXME: Unless they are only 2 regs?. */
341 regcache_cooked_read_unsigned (regcache, SIM_LM32_R1_REGNUM, &l);
342 return_buffer = l;
343 read_memory (return_buffer, valbuf, TYPE_LENGTH (type));
344 }
345 }
346
347 /* Write into appropriate registers a function return value of type
348 TYPE, given in virtual format. */
349 static void
350 lm32_store_return_value (struct type *type, struct regcache *regcache,
351 const gdb_byte *valbuf)
352 {
353 struct gdbarch *gdbarch = get_regcache_arch (regcache);
354 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
355 ULONGEST val;
356 int len = TYPE_LENGTH (type);
357
358 if (len <= 4)
359 {
360 val = extract_unsigned_integer (valbuf, len, byte_order);
361 regcache_cooked_write_unsigned (regcache, SIM_LM32_R1_REGNUM, val);
362 }
363 else if (len <= 8)
364 {
365 val = extract_unsigned_integer (valbuf, 4, byte_order);
366 regcache_cooked_write_unsigned (regcache, SIM_LM32_R1_REGNUM, val);
367 val = extract_unsigned_integer (valbuf + 4, len - 4, byte_order);
368 regcache_cooked_write_unsigned (regcache, SIM_LM32_R2_REGNUM, val);
369 }
370 else
371 error (_("lm32_store_return_value: type length too large."));
372 }
373
374 /* Determine whether a functions return value is in a register or memory. */
375 static enum return_value_convention
376 lm32_return_value (struct gdbarch *gdbarch, struct type *func_type,
377 struct type *valtype, struct regcache *regcache,
378 gdb_byte *readbuf, const gdb_byte *writebuf)
379 {
380 enum type_code code = TYPE_CODE (valtype);
381
382 if (code == TYPE_CODE_STRUCT
383 || code == TYPE_CODE_UNION
384 || code == TYPE_CODE_ARRAY || TYPE_LENGTH (valtype) > 8)
385 return RETURN_VALUE_STRUCT_CONVENTION;
386
387 if (readbuf)
388 lm32_extract_return_value (valtype, regcache, readbuf);
389 if (writebuf)
390 lm32_store_return_value (valtype, regcache, writebuf);
391
392 return RETURN_VALUE_REGISTER_CONVENTION;
393 }
394
395 static CORE_ADDR
396 lm32_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
397 {
398 return frame_unwind_register_unsigned (next_frame, SIM_LM32_PC_REGNUM);
399 }
400
401 static CORE_ADDR
402 lm32_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
403 {
404 return frame_unwind_register_unsigned (next_frame, SIM_LM32_SP_REGNUM);
405 }
406
407 static struct frame_id
408 lm32_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
409 {
410 CORE_ADDR sp = get_frame_register_unsigned (this_frame, SIM_LM32_SP_REGNUM);
411
412 return frame_id_build (sp, get_frame_pc (this_frame));
413 }
414
415 /* Put here the code to store, into fi->saved_regs, the addresses of
416 the saved registers of frame described by FRAME_INFO. This
417 includes special registers such as pc and fp saved in special ways
418 in the stack frame. sp is even more special: the address we return
419 for it IS the sp for the next frame. */
420
421 static struct lm32_frame_cache *
422 lm32_frame_cache (struct frame_info *this_frame, void **this_prologue_cache)
423 {
424 CORE_ADDR prologue_pc;
425 CORE_ADDR current_pc;
426 ULONGEST prev_sp;
427 ULONGEST this_base;
428 struct lm32_frame_cache *info;
429 int prefixed;
430 unsigned long instruction;
431 int op;
432 int offsets[32];
433 int i;
434 long immediate;
435
436 if ((*this_prologue_cache))
437 return (*this_prologue_cache);
438
439 info = FRAME_OBSTACK_ZALLOC (struct lm32_frame_cache);
440 (*this_prologue_cache) = info;
441 info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
442
443 info->pc = get_frame_func (this_frame);
444 current_pc = get_frame_pc (this_frame);
445 lm32_analyze_prologue (get_frame_arch (this_frame),
446 info->pc, current_pc, info);
447
448 /* Compute the frame's base, and the previous frame's SP. */
449 this_base = get_frame_register_unsigned (this_frame, SIM_LM32_SP_REGNUM);
450 prev_sp = this_base + info->size;
451 info->base = this_base;
452
453 /* Convert callee save offsets into addresses. */
454 for (i = 0; i < gdbarch_num_regs (get_frame_arch (this_frame)) - 1; i++)
455 {
456 if (trad_frame_addr_p (info->saved_regs, i))
457 info->saved_regs[i].addr = this_base + info->saved_regs[i].addr;
458 }
459
460 /* The call instruction moves the caller's PC in the callee's RA register.
461 Since this is an unwind, do the reverse. Copy the location of RA register
462 into PC (the address / regnum) so that a request for PC will be
463 converted into a request for the RA register. */
464 info->saved_regs[SIM_LM32_PC_REGNUM] = info->saved_regs[SIM_LM32_RA_REGNUM];
465
466 /* The previous frame's SP needed to be computed. Save the computed value. */
467 trad_frame_set_value (info->saved_regs, SIM_LM32_SP_REGNUM, prev_sp);
468
469 return info;
470 }
471
472 static void
473 lm32_frame_this_id (struct frame_info *this_frame, void **this_cache,
474 struct frame_id *this_id)
475 {
476 struct lm32_frame_cache *cache = lm32_frame_cache (this_frame, this_cache);
477
478 /* This marks the outermost frame. */
479 if (cache->base == 0)
480 return;
481
482 (*this_id) = frame_id_build (cache->base, cache->pc);
483 }
484
485 static struct value *
486 lm32_frame_prev_register (struct frame_info *this_frame,
487 void **this_prologue_cache, int regnum)
488 {
489 struct lm32_frame_cache *info;
490
491 info = lm32_frame_cache (this_frame, this_prologue_cache);
492 return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
493 }
494
495 static const struct frame_unwind lm32_frame_unwind = {
496 NORMAL_FRAME,
497 lm32_frame_this_id,
498 lm32_frame_prev_register,
499 NULL,
500 default_frame_sniffer
501 };
502
503 static CORE_ADDR
504 lm32_frame_base_address (struct frame_info *this_frame, void **this_cache)
505 {
506 struct lm32_frame_cache *info = lm32_frame_cache (this_frame, this_cache);
507
508 return info->base;
509 }
510
511 static const struct frame_base lm32_frame_base = {
512 &lm32_frame_unwind,
513 lm32_frame_base_address,
514 lm32_frame_base_address,
515 lm32_frame_base_address
516 };
517
518 static CORE_ADDR
519 lm32_frame_align (struct gdbarch *gdbarch, CORE_ADDR sp)
520 {
521 /* Align to the size of an instruction (so that they can safely be
522 pushed onto the stack. */
523 return sp & ~3;
524 }
525
526 static struct gdbarch *
527 lm32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
528 {
529 struct gdbarch *gdbarch;
530 struct gdbarch_tdep *tdep;
531
532 /* If there is already a candidate, use it. */
533 arches = gdbarch_list_lookup_by_info (arches, &info);
534 if (arches != NULL)
535 return arches->gdbarch;
536
537 /* None found, create a new architecture from the information provided. */
538 tdep = XMALLOC (struct gdbarch_tdep);
539 gdbarch = gdbarch_alloc (&info, tdep);
540
541 /* Type sizes. */
542 set_gdbarch_short_bit (gdbarch, 16);
543 set_gdbarch_int_bit (gdbarch, 32);
544 set_gdbarch_long_bit (gdbarch, 32);
545 set_gdbarch_long_long_bit (gdbarch, 64);
546 set_gdbarch_float_bit (gdbarch, 32);
547 set_gdbarch_double_bit (gdbarch, 64);
548 set_gdbarch_long_double_bit (gdbarch, 64);
549 set_gdbarch_ptr_bit (gdbarch, 32);
550
551 /* Register info. */
552 set_gdbarch_num_regs (gdbarch, SIM_LM32_NUM_REGS);
553 set_gdbarch_sp_regnum (gdbarch, SIM_LM32_SP_REGNUM);
554 set_gdbarch_pc_regnum (gdbarch, SIM_LM32_PC_REGNUM);
555 set_gdbarch_register_name (gdbarch, lm32_register_name);
556 set_gdbarch_register_type (gdbarch, lm32_register_type);
557 set_gdbarch_cannot_store_register (gdbarch, lm32_cannot_store_register);
558
559 /* Frame info. */
560 set_gdbarch_skip_prologue (gdbarch, lm32_skip_prologue);
561 set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
562 set_gdbarch_decr_pc_after_break (gdbarch, 0);
563 set_gdbarch_frame_args_skip (gdbarch, 0);
564
565 /* Frame unwinding. */
566 set_gdbarch_frame_align (gdbarch, lm32_frame_align);
567 frame_base_set_default (gdbarch, &lm32_frame_base);
568 set_gdbarch_unwind_pc (gdbarch, lm32_unwind_pc);
569 set_gdbarch_unwind_sp (gdbarch, lm32_unwind_sp);
570 set_gdbarch_dummy_id (gdbarch, lm32_dummy_id);
571 frame_unwind_append_unwinder (gdbarch, &lm32_frame_unwind);
572
573 /* Breakpoints. */
574 set_gdbarch_breakpoint_from_pc (gdbarch, lm32_breakpoint_from_pc);
575 set_gdbarch_have_nonsteppable_watchpoint (gdbarch, 1);
576
577 /* Calling functions in the inferior. */
578 set_gdbarch_push_dummy_call (gdbarch, lm32_push_dummy_call);
579 set_gdbarch_return_value (gdbarch, lm32_return_value);
580
581 /* Instruction disassembler. */
582 set_gdbarch_print_insn (gdbarch, print_insn_lm32);
583
584 lm32_add_reggroups (gdbarch);
585 set_gdbarch_register_reggroup_p (gdbarch, lm32_register_reggroup_p);
586
587 return gdbarch;
588 }
589
590 void
591 _initialize_lm32_tdep (void)
592 {
593 register_gdbarch_init (bfd_arch_lm32, lm32_gdbarch_init);
594 }
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