* mn10300-tdep.c (mn10300_frame_chain): Account for space saved
[deliverable/binutils-gdb.git] / gdb / mn10300-tdep.c
1 /* Target-dependent code for the Matsushita MN10300 for GDB, the GNU debugger.
2 Copyright 1996, 1997, 1998 Free Software Foundation, Inc.
3
4 This file is part of GDB.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
19
20 #include "defs.h"
21 #include "frame.h"
22 #include "inferior.h"
23 #include "obstack.h"
24 #include "target.h"
25 #include "value.h"
26 #include "bfd.h"
27 #include "gdb_string.h"
28 #include "gdbcore.h"
29 #include "symfile.h"
30
31 char *mn10300_generic_register_names[] = REGISTER_NAMES;
32
33 /* start-sanitize-am33 */
34 char *am33_register_names [] =
35 { "d0", "d1", "d2", "d3", "a0", "a1", "a2", "a3",
36 "sp", "pc", "mdr", "psw", "lir", "lar", "",
37 "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
38 "ssp", "msp", "usp", "mcrh", "mcrl", "mcvf", "", "", ""};
39 /* end-sanitize-am33 */
40
41
42 /* Set offsets of registers saved by movm instruction.
43 This is a helper function for mn10300_analyze_prologue. */
44
45 static void
46 set_movm_offsets (fi, found_movm)
47 struct frame_info *fi;
48 int found_movm;
49 {
50 if (fi == NULL || found_movm == 0)
51 return;
52 fi->fsr.regs[7] = fi->frame;
53 fi->fsr.regs[6] = fi->frame + 4;
54 fi->fsr.regs[3] = fi->frame + 8;
55 fi->fsr.regs[2] = fi->frame + 12;
56 /* start-sanitize-am33 */
57 fi->fsr.regs[E0_REGNUM+5] = fi->frame + 16;
58 fi->fsr.regs[E0_REGNUM+4] = fi->frame + 20;
59 fi->fsr.regs[E0_REGNUM+3] = fi->frame + 24;
60 fi->fsr.regs[E0_REGNUM+2] = fi->frame + 28;
61 /* end-sanitize-am33 */
62 }
63
64
65 /* The main purpose of this file is dealing with prologues to extract
66 information about stack frames and saved registers.
67
68 For reference here's how prologues look on the mn10300:
69
70 With frame pointer:
71 movm [d2,d3,a2,a3],sp
72 mov sp,a3
73 add <size>,sp
74
75 Without frame pointer:
76 movm [d2,d3,a2,a3],sp (if needed)
77 add <size>,sp
78
79 One day we might keep the stack pointer constant, that won't
80 change the code for prologues, but it will make the frame
81 pointerless case much more common. */
82
83 /* Analyze the prologue to determine where registers are saved,
84 the end of the prologue, etc etc. Return the end of the prologue
85 scanned.
86
87 We store into FI (if non-null) several tidbits of information:
88
89 * stack_size -- size of this stack frame. Note that if we stop in
90 certain parts of the prologue/epilogue we may claim the size of the
91 current frame is zero. This happens when the current frame has
92 not been allocated yet or has already been deallocated.
93
94 * fsr -- Addresses of registers saved in the stack by this frame.
95
96 * status -- A (relatively) generic status indicator. It's a bitmask
97 with the following bits:
98
99 MY_FRAME_IN_SP: The base of the current frame is actually in
100 the stack pointer. This can happen for frame pointerless
101 functions, or cases where we're stopped in the prologue/epilogue
102 itself. For these cases mn10300_analyze_prologue will need up
103 update fi->frame before returning or analyzing the register
104 save instructions.
105
106 MY_FRAME_IN_FP: The base of the current frame is in the
107 frame pointer register ($a2).
108
109 NO_MORE_FRAMES: Set this if the current frame is "start" or
110 if the first instruction looks like mov <imm>,sp. This tells
111 frame chain to not bother trying to unwind past this frame. */
112
113 #define MY_FRAME_IN_SP 0x1
114 #define MY_FRAME_IN_FP 0x2
115 #define NO_MORE_FRAMES 0x4
116
117 static CORE_ADDR
118 mn10300_analyze_prologue (fi, pc)
119 struct frame_info *fi;
120 CORE_ADDR pc;
121 {
122 CORE_ADDR func_addr, func_end, addr, stop;
123 CORE_ADDR stack_size;
124 int imm_size;
125 unsigned char buf[4];
126 int status, found_movm = 0;
127 char *name;
128
129 /* Use the PC in the frame if it's provided to look up the
130 start of this function. */
131 pc = (fi ? fi->pc : pc);
132
133 /* Find the start of this function. */
134 status = find_pc_partial_function (pc, &name, &func_addr, &func_end);
135
136 /* Do nothing if we couldn't find the start of this function or if we're
137 stopped at the first instruction in the prologue. */
138 if (status == 0)
139 return pc;
140
141 /* If we're in start, then give up. */
142 if (strcmp (name, "start") == 0)
143 {
144 fi->status = NO_MORE_FRAMES;
145 return pc;
146 }
147
148 /* At the start of a function our frame is in the stack pointer. */
149 if (fi)
150 fi->status = MY_FRAME_IN_SP;
151
152 /* Get the next two bytes into buf, we need two because rets is a two
153 byte insn and the first isn't enough to uniquely identify it. */
154 status = read_memory_nobpt (pc, buf, 2);
155 if (status != 0)
156 return pc;
157
158 /* If we're physically on an "rets" instruction, then our frame has
159 already been deallocated. Note this can also be true for retf
160 and ret if they specify a size of zero.
161
162 In this case fi->frame is bogus, we need to fix it. */
163 if (fi && buf[0] == 0xf0 && buf[1] == 0xfc)
164 {
165 if (fi->next == NULL)
166 fi->frame = read_sp ();
167 return fi->pc;
168 }
169
170 /* Similarly if we're stopped on the first insn of a prologue as our
171 frame hasn't been allocated yet. */
172 if (fi && fi->pc == func_addr)
173 {
174 if (fi->next == NULL)
175 fi->frame = read_sp ();
176 return fi->pc;
177 }
178
179 /* Figure out where to stop scanning. */
180 stop = fi ? fi->pc : func_end;
181
182 /* Don't walk off the end of the function. */
183 stop = stop > func_end ? func_end : stop;
184
185 /* Start scanning on the first instruction of this function. */
186 addr = func_addr;
187
188 /* Suck in two bytes. */
189 status = read_memory_nobpt (addr, buf, 2);
190 if (status != 0)
191 {
192 if (fi && fi->next == NULL && fi->status & MY_FRAME_IN_SP)
193 fi->frame = read_sp ();
194 return addr;
195 }
196
197 /* First see if this insn sets the stack pointer; if so, it's something
198 we won't understand, so quit now. */
199 if (buf[0] == 0xf2 && (buf[1] & 0xf3) == 0xf0)
200 {
201 if (fi)
202 fi->status = NO_MORE_FRAMES;
203 return addr;
204 }
205
206 /* Now look for movm [regs],sp, which saves the callee saved registers.
207
208 At this time we don't know if fi->frame is valid, so we only note
209 that we encountered a movm instruction. Later, we'll set the entries
210 in fsr.regs as needed. */
211 if (buf[0] == 0xcf)
212 {
213 found_movm = 1;
214 addr += 2;
215
216 /* Quit now if we're beyond the stop point. */
217 if (addr >= stop)
218 {
219 /* Fix fi->frame since it's bogus at this point. */
220 if (fi && fi->next == NULL)
221 fi->frame = read_sp ();
222
223 /* Note if/where callee saved registers were saved. */
224 set_movm_offsets (fi, found_movm);
225 return addr;
226 }
227
228 /* Get the next two bytes so the prologue scan can continue. */
229 status = read_memory_nobpt (addr, buf, 2);
230 if (status != 0)
231 {
232 /* Fix fi->frame since it's bogus at this point. */
233 if (fi && fi->next == NULL)
234 fi->frame = read_sp ();
235
236 /* Note if/where callee saved registers were saved. */
237 set_movm_offsets (fi, found_movm);
238 return addr;
239 }
240 }
241
242 /* Now see if we set up a frame pointer via "mov sp,a3" */
243 if (buf[0] == 0x3f)
244 {
245 addr += 1;
246
247 /* The frame pointer is now valid. */
248 if (fi)
249 {
250 fi->status |= MY_FRAME_IN_FP;
251 fi->status &= ~MY_FRAME_IN_SP;
252 }
253
254 /* Quit now if we're beyond the stop point. */
255 if (addr >= stop)
256 {
257 /* Note if/where callee saved registers were saved. */
258 set_movm_offsets (fi, found_movm);
259 return addr;
260 }
261
262 /* Get two more bytes so scanning can continue. */
263 status = read_memory_nobpt (addr, buf, 2);
264 if (status != 0)
265 {
266 /* Note if/where callee saved registers were saved. */
267 set_movm_offsets (fi, found_movm);
268 return addr;
269 }
270 }
271
272 /* Next we should allocate the local frame. No more prologue insns
273 are found after allocating the local frame.
274
275 Search for add imm8,sp (0xf8feXX)
276 or add imm16,sp (0xfafeXXXX)
277 or add imm32,sp (0xfcfeXXXXXXXX).
278
279 If none of the above was found, then this prologue has no
280 additional stack. */
281
282 status = read_memory_nobpt (addr, buf, 2);
283 if (status != 0)
284 {
285 /* Fix fi->frame if it's bogus at this point. */
286 if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
287 fi->frame = read_sp ();
288
289 /* Note if/where callee saved registers were saved. */
290 set_movm_offsets (fi, found_movm);
291 return addr;
292 }
293
294 imm_size = 0;
295 if (buf[0] == 0xf8 && buf[1] == 0xfe)
296 imm_size = 1;
297 else if (buf[0] == 0xfa && buf[1] == 0xfe)
298 imm_size = 2;
299 else if (buf[0] == 0xfc && buf[1] == 0xfe)
300 imm_size = 4;
301
302 if (imm_size != 0)
303 {
304 /* Suck in imm_size more bytes, they'll hold the size of the
305 current frame. */
306 status = read_memory_nobpt (addr + 2, buf, imm_size);
307 if (status != 0)
308 {
309 /* Fix fi->frame if it's bogus at this point. */
310 if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
311 fi->frame = read_sp ();
312
313 /* Note if/where callee saved registers were saved. */
314 set_movm_offsets (fi, found_movm);
315 return addr;
316 }
317
318 /* Note the size of the stack in the frame info structure. */
319 stack_size = extract_signed_integer (buf, imm_size);
320 if (fi)
321 fi->stack_size = stack_size;
322
323 /* We just consumed 2 + imm_size bytes. */
324 addr += 2 + imm_size;
325
326 /* No more prologue insns follow, so begin preparation to return. */
327 /* Fix fi->frame if it's bogus at this point. */
328 if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
329 fi->frame = read_sp ();
330
331 /* Note if/where callee saved registers were saved. */
332 set_movm_offsets (fi, found_movm);
333 return addr;
334 }
335
336 /* We never found an insn which allocates local stack space, regardless
337 this is the end of the prologue. */
338 /* Fix fi->frame if it's bogus at this point. */
339 if (fi && fi->next == NULL && (fi->status & MY_FRAME_IN_SP))
340 fi->frame = read_sp ();
341
342 /* Note if/where callee saved registers were saved. */
343 set_movm_offsets (fi, found_movm);
344 return addr;
345 }
346
347 /* Function: frame_chain
348 Figure out and return the caller's frame pointer given current
349 frame_info struct.
350
351 We don't handle dummy frames yet but we would probably just return the
352 stack pointer that was in use at the time the function call was made? */
353
354 CORE_ADDR
355 mn10300_frame_chain (fi)
356 struct frame_info *fi;
357 {
358 struct frame_info dummy_frame;
359
360 /* Walk through the prologue to determine the stack size,
361 location of saved registers, end of the prologue, etc. */
362 if (fi->status == 0)
363 mn10300_analyze_prologue (fi, (CORE_ADDR)0);
364
365 /* Quit now if mn10300_analyze_prologue set NO_MORE_FRAMES. */
366 if (fi->status & NO_MORE_FRAMES)
367 return 0;
368
369 /* Now that we've analyzed our prologue, determine the frame
370 pointer for our caller.
371
372 If our caller has a frame pointer, then we need to
373 find the entry value of $a3 to our function.
374
375 If fsr.regs[7] is nonzero, then it's at the memory
376 location pointed to by fsr.regs[7].
377
378 Else it's still in $a3.
379
380 If our caller does not have a frame pointer, then his
381 frame base is fi->frame + -caller's stack size. */
382
383 /* The easiest way to get that info is to analyze our caller's frame.
384
385 So we set up a dummy frame and call mn10300_analyze_prologue to
386 find stuff for us. */
387 dummy_frame.pc = FRAME_SAVED_PC (fi);
388 dummy_frame.frame = fi->frame;
389 memset (dummy_frame.fsr.regs, '\000', sizeof dummy_frame.fsr.regs);
390 dummy_frame.status = 0;
391 dummy_frame.stack_size = 0;
392 mn10300_analyze_prologue (&dummy_frame);
393
394 if (dummy_frame.status & MY_FRAME_IN_FP)
395 {
396 /* Our caller has a frame pointer. So find the frame in $a3 or
397 in the stack. */
398 if (fi->fsr.regs[7])
399 return (read_memory_integer (fi->fsr.regs[FP_REGNUM], REGISTER_SIZE));
400 else
401 return read_register (FP_REGNUM);
402 }
403 else
404 {
405 int adjust = 0;
406
407 adjust += (fi->fsr.regs[2] ? 4 : 0);
408 adjust += (fi->fsr.regs[3] ? 4 : 0);
409 adjust += (fi->fsr.regs[6] ? 4 : 0);
410 adjust += (fi->fsr.regs[7] ? 4 : 0);
411 /* start-sanitize-am33 */
412 adjust += (fi->fsr.regs[E0_REGNUM+5] ? 4 : 0);
413 adjust += (fi->fsr.regs[E0_REGNUM+4] ? 4 : 0);
414 adjust += (fi->fsr.regs[E0_REGNUM+3] ? 4 : 0);
415 adjust += (fi->fsr.regs[E0_REGNUM+2] ? 4 : 0);
416 /* end-sanitize-am33 */
417
418 /* Our caller does not have a frame pointer. So his frame starts
419 at the base of our frame (fi->frame) + register save space. */
420 return fi->frame + adjust;
421 }
422 }
423
424 /* Function: skip_prologue
425 Return the address of the first inst past the prologue of the function. */
426
427 CORE_ADDR
428 mn10300_skip_prologue (pc)
429 CORE_ADDR pc;
430 {
431 /* We used to check the debug symbols, but that can lose if
432 we have a null prologue. */
433 return mn10300_analyze_prologue (NULL, pc);
434 }
435
436
437 /* Function: pop_frame
438 This routine gets called when either the user uses the `return'
439 command, or the call dummy breakpoint gets hit. */
440
441 void
442 mn10300_pop_frame (frame)
443 struct frame_info *frame;
444 {
445 int regnum;
446
447 if (PC_IN_CALL_DUMMY(frame->pc, frame->frame, frame->frame))
448 generic_pop_dummy_frame ();
449 else
450 {
451 write_register (PC_REGNUM, FRAME_SAVED_PC (frame));
452
453 /* Restore any saved registers. */
454 for (regnum = 0; regnum < NUM_REGS; regnum++)
455 if (frame->fsr.regs[regnum] != 0)
456 {
457 ULONGEST value;
458
459 value = read_memory_unsigned_integer (frame->fsr.regs[regnum],
460 REGISTER_RAW_SIZE (regnum));
461 write_register (regnum, value);
462 }
463
464 /* Actually cut back the stack. */
465 write_register (SP_REGNUM, FRAME_FP (frame));
466
467 /* Don't we need to set the PC?!? XXX FIXME. */
468 }
469
470 /* Throw away any cached frame information. */
471 flush_cached_frames ();
472 }
473
474 /* Function: push_arguments
475 Setup arguments for a call to the target. Arguments go in
476 order on the stack. */
477
478 CORE_ADDR
479 mn10300_push_arguments (nargs, args, sp, struct_return, struct_addr)
480 int nargs;
481 value_ptr *args;
482 CORE_ADDR sp;
483 unsigned char struct_return;
484 CORE_ADDR struct_addr;
485 {
486 int argnum = 0;
487 int len = 0;
488 int stack_offset = 0;
489 int regsused = struct_return ? 1 : 0;
490
491 /* This should be a nop, but align the stack just in case something
492 went wrong. Stacks are four byte aligned on the mn10300. */
493 sp &= ~3;
494
495 /* Now make space on the stack for the args.
496
497 XXX This doesn't appear to handle pass-by-invisible reference
498 arguments. */
499 for (argnum = 0; argnum < nargs; argnum++)
500 {
501 int arg_length = (TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 3) & ~3;
502
503 while (regsused < 2 && arg_length > 0)
504 {
505 regsused++;
506 arg_length -= 4;
507 }
508 len += arg_length;
509 }
510
511 /* Allocate stack space. */
512 sp -= len;
513
514 regsused = struct_return ? 1 : 0;
515 /* Push all arguments onto the stack. */
516 for (argnum = 0; argnum < nargs; argnum++)
517 {
518 int len;
519 char *val;
520
521 /* XXX Check this. What about UNIONS? */
522 if (TYPE_CODE (VALUE_TYPE (*args)) == TYPE_CODE_STRUCT
523 && TYPE_LENGTH (VALUE_TYPE (*args)) > 8)
524 {
525 /* XXX Wrong, we want a pointer to this argument. */
526 len = TYPE_LENGTH (VALUE_TYPE (*args));
527 val = (char *)VALUE_CONTENTS (*args);
528 }
529 else
530 {
531 len = TYPE_LENGTH (VALUE_TYPE (*args));
532 val = (char *)VALUE_CONTENTS (*args);
533 }
534
535 while (regsused < 2 && len > 0)
536 {
537 write_register (regsused, extract_unsigned_integer (val, 4));
538 val += 4;
539 len -= 4;
540 regsused++;
541 }
542
543 while (len > 0)
544 {
545 write_memory (sp + stack_offset, val, 4);
546 len -= 4;
547 val += 4;
548 stack_offset += 4;
549 }
550
551 args++;
552 }
553
554 /* Make space for the flushback area. */
555 sp -= 8;
556 return sp;
557 }
558
559 /* Function: push_return_address (pc)
560 Set up the return address for the inferior function call.
561 Needed for targets where we don't actually execute a JSR/BSR instruction */
562
563 CORE_ADDR
564 mn10300_push_return_address (pc, sp)
565 CORE_ADDR pc;
566 CORE_ADDR sp;
567 {
568 unsigned char buf[4];
569
570 store_unsigned_integer (buf, 4, CALL_DUMMY_ADDRESS ());
571 write_memory (sp - 4, buf, 4);
572 return sp - 4;
573 }
574
575 /* Function: store_struct_return (addr,sp)
576 Store the structure value return address for an inferior function
577 call. */
578
579 CORE_ADDR
580 mn10300_store_struct_return (addr, sp)
581 CORE_ADDR addr;
582 CORE_ADDR sp;
583 {
584 /* The structure return address is passed as the first argument. */
585 write_register (0, addr);
586 return sp;
587 }
588
589 /* Function: frame_saved_pc
590 Find the caller of this frame. We do this by seeing if RP_REGNUM
591 is saved in the stack anywhere, otherwise we get it from the
592 registers. If the inner frame is a dummy frame, return its PC
593 instead of RP, because that's where "caller" of the dummy-frame
594 will be found. */
595
596 CORE_ADDR
597 mn10300_frame_saved_pc (fi)
598 struct frame_info *fi;
599 {
600 int adjust = 0;
601
602 adjust += (fi->fsr.regs[2] ? 4 : 0);
603 adjust += (fi->fsr.regs[3] ? 4 : 0);
604 adjust += (fi->fsr.regs[6] ? 4 : 0);
605 adjust += (fi->fsr.regs[7] ? 4 : 0);
606 /* start-sanitize-am33 */
607 adjust += (fi->fsr.regs[E0_REGNUM+5] ? 4 : 0);
608 adjust += (fi->fsr.regs[E0_REGNUM+4] ? 4 : 0);
609 adjust += (fi->fsr.regs[E0_REGNUM+3] ? 4 : 0);
610 adjust += (fi->fsr.regs[E0_REGNUM+2] ? 4 : 0);
611 /* end-sanitize-am33 */
612
613 return (read_memory_integer (fi->frame + adjust, REGISTER_SIZE));
614 }
615
616 void
617 get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval)
618 char *raw_buffer;
619 int *optimized;
620 CORE_ADDR *addrp;
621 struct frame_info *frame;
622 int regnum;
623 enum lval_type *lval;
624 {
625 generic_get_saved_register (raw_buffer, optimized, addrp,
626 frame, regnum, lval);
627 }
628
629 /* Function: init_extra_frame_info
630 Setup the frame's frame pointer, pc, and frame addresses for saved
631 registers. Most of the work is done in mn10300_analyze_prologue().
632
633 Note that when we are called for the last frame (currently active frame),
634 that fi->pc and fi->frame will already be setup. However, fi->frame will
635 be valid only if this routine uses FP. For previous frames, fi-frame will
636 always be correct. mn10300_analyze_prologue will fix fi->frame if
637 it's not valid.
638
639 We can be called with the PC in the call dummy under two circumstances.
640 First, during normal backtracing, second, while figuring out the frame
641 pointer just prior to calling the target function (see run_stack_dummy). */
642
643 void
644 mn10300_init_extra_frame_info (fi)
645 struct frame_info *fi;
646 {
647 if (fi->next)
648 fi->pc = FRAME_SAVED_PC (fi->next);
649
650 memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs);
651 fi->status = 0;
652 fi->stack_size = 0;
653
654 mn10300_analyze_prologue (fi, 0);
655 }
656
657 /* This can be made more generic later. */
658 static void
659 set_machine_hook (filename)
660 char *filename;
661 {
662 int i;
663
664 if (bfd_get_mach (exec_bfd) == bfd_mach_mn10300
665 || bfd_get_mach (exec_bfd) == 0)
666 {
667 for (i = 0; i < NUM_REGS; i++)
668 reg_names[i] = mn10300_generic_register_names[i];
669 }
670
671 /* start-sanitize-am33 */
672 if (bfd_get_mach (exec_bfd) == bfd_mach_am33)
673 {
674 for (i = 0; i < NUM_REGS; i++)
675 reg_names[i] = am33_register_names[i];
676 }
677 /* end-sanitize-am33 */
678 }
679
680 void
681 _initialize_mn10300_tdep ()
682 {
683 /* printf("_initialize_mn10300_tdep\n"); */
684
685 tm_print_insn = print_insn_mn10300;
686
687 specify_exec_file_hook (set_machine_hook);
688 }
689
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