1 /* Target-dependent code for the Matsushita MN10200 for GDB, the GNU debugger.
2 Copyright 1997 Free Software Foundation, Inc.
4 This file is part of GDB.
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.
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.
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. */
27 #include "gdb_string.h"
31 /* The main purpose of this file is dealing with prologues to extract
32 information about stack frames and saved registers.
34 For reference here's how prologues look on the mn10200:
40 Register saves for d2, d3, a3 as needed. Saves start
41 at fp - <size> and work towards higher addresses. Note
42 that the saves are actually done off the stack pointer
43 in the prologue! This makes for smaller code and easier
44 prologue scanning as the displacement fields will never
47 Without frame pointer:
49 Register saves for d2, d3, a3 as needed. Saves start
50 at sp and work towards higher addresses.
53 One day we might keep the stack pointer constant, that won't
54 change the code for prologues, but it will make the frame
55 pointerless case much more common. */
57 /* Analyze the prologue to determine where registers are saved,
58 the end of the prologue, etc etc. Return the end of the prologue
61 We store into FI (if non-null) several tidbits of information:
63 * stack_size -- size of this stack frame. Note that if we stop in
64 certain parts of the prologue/epilogue we may claim the size of the
65 current frame is zero. This happens when the current frame has
66 not been allocated yet or has already been deallocated.
68 * fsr -- Addresses of registers saved in the stack by this frame.
70 * status -- A (relatively) generic status indicator. It's a bitmask
71 with the following bits:
73 MY_FRAME_IN_SP: The base of the current frame is actually in
74 the stack pointer. This can happen for frame pointerless
75 functions, or cases where we're stopped in the prologue/epilogue
76 itself. For these cases mn10200_analyze_prologue will need up
77 update fi->frame before returning or analyzing the register
80 MY_FRAME_IN_FP: The base of the current frame is in the
81 frame pointer register ($a2).
83 CALLER_A2_IN_A0: $a2 from the caller's frame is temporarily
84 in $a0. This can happen if we're stopped in the prologue.
86 NO_MORE_FRAMES: Set this if the current frame is "start" or
87 if the first instruction looks like mov <imm>,sp. This tells
88 frame chain to not bother trying to unwind past this frame. */
90 #define MY_FRAME_IN_SP 0x1
91 #define MY_FRAME_IN_FP 0x2
92 #define CALLER_A2_IN_A0 0x4
93 #define NO_MORE_FRAMES 0x8
96 mn10200_analyze_prologue (fi, pc)
97 struct frame_info *fi;
100 CORE_ADDR func_addr, func_end, addr, stop;
101 CORE_ADDR stack_size;
102 unsigned char buf[4];
106 /* Use the PC in the frame if it's provided to look up the
107 start of this function. */
108 pc = (fi ? fi->pc : pc);
110 /* Find the start of this function. */
111 status = find_pc_partial_function (pc, &name, &func_addr, &func_end);
113 /* Do nothing if we couldn't find the start of this function or if we're
114 stopped at the first instruction in the prologue. */
118 /* If we're in start, then give up. */
119 if (strcmp (name, "start") == 0)
121 fi->status = NO_MORE_FRAMES;
125 /* At the start of a function our frame is in the stack pointer. */
127 fi->status = MY_FRAME_IN_SP;
129 /* If we're physically on an RTS instruction, then our frame has already
132 fi->frame is bogus, we need to fix it. */
133 if (fi && fi->pc + 1 == func_end)
135 status = target_read_memory (fi->pc, buf, 1);
138 fi->frame = read_sp ();
144 fi->frame = read_sp ();
149 /* Similarly if we're stopped on the first insn of a prologue as our
150 frame hasn't been allocated yet. */
151 if (fi && fi->pc == func_addr)
153 fi->frame = read_sp ();
157 /* Figure out where to stop scanning. */
158 stop = fi ? fi->pc : func_end;
160 /* Don't walk off the end of the function. */
161 stop = stop > func_end ? func_end : stop;
163 /* Start scanning on the first instruction of this function. */
166 status = target_read_memory (addr, buf, 2);
169 if (fi && fi->status & MY_FRAME_IN_SP)
170 fi->frame = read_sp ();
174 /* First see if this insn sets the stack pointer; if so, it's something
175 we won't understand, so quit now. */
177 || (buf[0] == 0xf4 && buf[1] == 0x77))
180 fi->status = NO_MORE_FRAMES;
184 /* Now see if we have a frame pointer.
186 Search for mov a2,a0 (0xf278)
187 then mov a3,a2 (0xf27e). */
189 if (buf[0] == 0xf2 && buf[1] == 0x78)
191 /* Our caller's $a2 will be found in $a0 now. Note it for
194 fi->status |= CALLER_A2_IN_A0;
198 /* We still haven't allocated our local stack. Handle this
199 as if we stopped on the first or last insn of a function. */
201 fi->frame = read_sp ();
205 status = target_read_memory (addr, buf, 2);
209 fi->frame = read_sp ();
212 if (buf[0] == 0xf2 && buf[1] == 0x7e)
216 /* Our frame pointer is valid now. */
219 fi->status |= MY_FRAME_IN_FP;
220 fi->status &= ~MY_FRAME_IN_SP;
228 fi->frame = read_sp ();
233 /* Next we should allocate the local frame.
235 Search for add imm8,a3 (0xd3XX)
236 or add imm16,a3 (0xf70bXXXX)
237 or add imm24,a3 (0xf467XXXXXX).
239 If none of the above was found, then this prologue has
240 no stack, and therefore can't have any register saves,
242 status = target_read_memory (addr, buf, 2);
245 if (fi && (fi->status & MY_FRAME_IN_SP))
246 fi->frame = read_sp ();
251 stack_size = extract_signed_integer (&buf[1], 1);
253 fi->stack_size = stack_size;
257 if (fi && (fi->status & MY_FRAME_IN_SP))
258 fi->frame = read_sp () + stack_size;
262 else if (buf[0] == 0xf7 && buf[1] == 0x0b)
264 status = target_read_memory (addr + 2, buf, 2);
267 if (fi && (fi->status & MY_FRAME_IN_SP))
268 fi->frame = read_sp ();
271 stack_size = extract_signed_integer (buf, 2);
273 fi->stack_size = stack_size;
277 if (fi && (fi->status & MY_FRAME_IN_SP))
278 fi->frame = read_sp () + stack_size;
282 else if (buf[0] == 0xf4 && buf[1] == 0x67)
284 status = target_read_memory (addr + 2, buf, 3);
287 if (fi && (fi->status & MY_FRAME_IN_SP))
288 fi->frame = read_sp ();
291 stack_size = extract_signed_integer (buf, 3);
293 fi->stack_size = stack_size;
297 if (fi && (fi->status & MY_FRAME_IN_SP))
298 fi->frame = read_sp () + stack_size;
304 if (fi && (fi->status & MY_FRAME_IN_SP))
305 fi->frame = read_sp ();
309 /* At this point fi->frame needs to be correct.
311 If MY_FRAME_IN_SP is set, then we need to fix fi->frame so
312 that backtracing, find_frame_saved_regs, etc work correctly. */
313 if (fi && (fi->status & MY_FRAME_IN_SP) != 0)
314 fi->frame = read_sp () - fi->stack_size;
316 /* And last we have the register saves. These are relatively
317 simple because they're physically done off the stack pointer,
318 and thus the number of different instructions we need to
319 check is greatly reduced because we know the displacements
322 Search for movx d2,(X,a3) (0xf55eXX)
323 then movx d3,(X,a3) (0xf55fXX)
324 then mov a2,(X,a3) (0x5eXX) No frame pointer case
325 or mov a0,(X,a3) (0x5cXX) Frame pointer case. */
327 status = target_read_memory (addr, buf, 2);
330 if (buf[0] == 0xf5 && buf[1] == 0x5e)
334 status = target_read_memory (addr + 2, buf, 1);
337 fi->fsr.regs[2] = (fi->frame + stack_size
338 + extract_signed_integer (buf, 1));
343 status = target_read_memory (addr, buf, 2);
347 if (buf[0] == 0xf5 && buf[1] == 0x5f)
351 status = target_read_memory (addr + 2, buf, 1);
354 fi->fsr.regs[3] = (fi->frame + stack_size
355 + extract_signed_integer (buf, 1));
360 status = target_read_memory (addr, buf, 2);
364 if (buf[0] == 0x5e || buf[0] == 0x5c)
368 status = target_read_memory (addr + 1, buf, 1);
371 fi->fsr.regs[6] = (fi->frame + stack_size
372 + extract_signed_integer (buf, 1));
373 fi->status &= ~CALLER_A2_IN_A0;
383 /* Function: frame_chain
384 Figure out and return the caller's frame pointer given current
387 We don't handle dummy frames yet but we would probably just return the
388 stack pointer that was in use at the time the function call was made? */
391 mn10200_frame_chain (fi)
392 struct frame_info *fi;
394 struct frame_info dummy_frame;
396 /* Walk through the prologue to determine the stack size,
397 location of saved registers, end of the prologue, etc. */
399 mn10200_analyze_prologue (fi, (CORE_ADDR)0);
401 /* Quit now if mn10200_analyze_prologue set NO_MORE_FRAMES. */
402 if (fi->status & NO_MORE_FRAMES)
405 /* Now that we've analyzed our prologue, determine the frame
406 pointer for our caller.
408 If our caller has a frame pointer, then we need to
409 find the entry value of $a2 to our function.
411 If CALLER_A2_IN_A0, then the chain is in $a0.
413 If fsr.regs[6] is nonzero, then it's at the memory
414 location pointed to by fsr.regs[6].
416 Else it's still in $a2.
418 If our caller does not have a frame pointer, then his
419 frame base is fi->frame + caller's stack size + 4. */
421 /* The easiest way to get that info is to analyze our caller's frame.
423 So we set up a dummy frame and call mn10200_analyze_prologue to
424 find stuff for us. */
425 dummy_frame.pc = FRAME_SAVED_PC (fi);
426 dummy_frame.frame = fi->frame;
427 memset (dummy_frame.fsr.regs, '\000', sizeof dummy_frame.fsr.regs);
428 dummy_frame.status = 0;
429 dummy_frame.stack_size = 0;
430 mn10200_analyze_prologue (&dummy_frame);
432 if (dummy_frame.status & MY_FRAME_IN_FP)
434 /* Our caller has a frame pointer. So find the frame in $a2, $a0,
437 return (read_memory_integer (fi->fsr.regs[FP_REGNUM], REGISTER_SIZE)
439 else if (fi->status & CALLER_A2_IN_A0)
440 return read_register (4);
442 return read_register (FP_REGNUM);
446 /* Our caller does not have a frame pointer. So his frame starts
447 at the base of our frame (fi->frame) + <his size> + 4 (saved pc). */
448 return fi->frame + dummy_frame.stack_size + 4;
452 /* Function: skip_prologue
453 Return the address of the first inst past the prologue of the function. */
456 mn10200_skip_prologue (pc)
459 CORE_ADDR func_addr, func_end;
461 /* First check the symbol table. That'll be faster than scanning
462 the prologue instructions if we have debug sybmols. */
463 if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
465 struct symtab_and_line sal;
467 sal = find_pc_line (func_addr, 0);
469 if (sal.line != 0 && sal.end < func_end)
472 return mn10200_analyze_prologue (NULL, pc);
475 /* We couldn't find the start of this function, do nothing. */
479 /* Function: pop_frame
480 This routine gets called when either the user uses the `return'
481 command, or the call dummy breakpoint gets hit. */
484 mn10200_pop_frame (frame)
485 struct frame_info *frame;
489 if (PC_IN_CALL_DUMMY(frame->pc, frame->frame, frame->frame))
490 generic_pop_dummy_frame ();
493 write_register (PC_REGNUM, FRAME_SAVED_PC (frame));
495 /* Restore any saved registers. */
496 for (regnum = 0; regnum < NUM_REGS; regnum++)
497 if (frame->fsr.regs[regnum] != 0)
501 value = read_memory_unsigned_integer (frame->fsr.regs[regnum],
502 REGISTER_RAW_SIZE (regnum));
503 write_register (regnum, value);
506 /* Actually cut back the stack. */
507 write_register (SP_REGNUM, FRAME_FP (frame));
509 /* Don't we need to set the PC?!? XXX FIXME. */
512 /* Throw away any cached frame information. */
513 flush_cached_frames ();
516 /* Function: push_arguments
517 Setup arguments for a call to the target. Arguments go in
518 order on the stack. */
521 mn10200_push_arguments (nargs, args, sp, struct_return, struct_addr)
525 unsigned char struct_return;
526 CORE_ADDR struct_addr;
530 int stack_offset = 0;
532 /* This should be a nop, but align the stack just in case something
533 went wrong. Stacks are two byte aligned on the mn10200. */
536 /* Now make space on the stack for the args.
538 XXX This doesn't appear to handle pass-by-invisible reference
540 for (argnum = 0; argnum < nargs; argnum++)
541 len += ((TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 1) & ~1);
543 /* Allocate stack space. */
546 /* Push all arguments onto the stack. */
547 for (argnum = 0; argnum < nargs; argnum++)
552 /* XXX Check this. What about UNIONS? Size check looks
554 if (TYPE_CODE (VALUE_TYPE (*args)) == TYPE_CODE_STRUCT
555 && TYPE_LENGTH (VALUE_TYPE (*args)) > 8)
557 /* XXX Wrong, we want a pointer to this argument. */
558 len = TYPE_LENGTH (VALUE_TYPE (*args));
559 val = (char *)VALUE_CONTENTS (*args);
563 len = TYPE_LENGTH (VALUE_TYPE (*args));
564 val = (char *)VALUE_CONTENTS (*args);
569 /* XXX This looks wrong; we can have one and two byte args. */
570 write_memory (sp + stack_offset, val, 2);
582 /* Function: push_return_address (pc)
583 Set up the return address for the inferior function call.
584 Needed for targets where we don't actually execute a JSR/BSR instruction */
587 mn10200_push_return_address (pc, sp)
591 unsigned char buf[4];
593 store_unsigned_integer (buf, 4, CALL_DUMMY_ADDRESS ());
594 write_memory (sp - 4, buf, 4);
598 /* Function: frame_saved_pc
599 Find the caller of this frame. We do this by seeing if RP_REGNUM
600 is saved in the stack anywhere, otherwise we get it from the
601 registers. If the inner frame is a dummy frame, return its PC
602 instead of RP, because that's where "caller" of the dummy-frame
606 mn10200_frame_saved_pc (fi)
607 struct frame_info *fi;
609 /* The saved PC will always be at the base of the current frame. */
610 return (read_memory_integer (fi->frame, REGISTER_SIZE) & 0xffffff);
614 get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval)
618 struct frame_info *frame;
620 enum lval_type *lval;
622 generic_get_saved_register (raw_buffer, optimized, addrp,
623 frame, regnum, lval);
626 /* Function: init_extra_frame_info
627 Setup the frame's frame pointer, pc, and frame addresses for saved
628 registers. Most of the work is done in mn10200_analyze_prologue().
630 Note that when we are called for the last frame (currently active frame),
631 that fi->pc and fi->frame will already be setup. However, fi->frame will
632 be valid only if this routine uses FP. For previous frames, fi-frame will
633 always be correct. mn10200_analyze_prologue will fix fi->frame if
636 We can be called with the PC in the call dummy under two circumstances.
637 First, during normal backtracing, second, while figuring out the frame
638 pointer just prior to calling the target function (see run_stack_dummy). */
641 mn10200_init_extra_frame_info (fi)
642 struct frame_info *fi;
645 fi->pc = FRAME_SAVED_PC (fi->next);
647 memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs);
651 mn10200_analyze_prologue (fi, 0);
655 _initialize_mn10200_tdep ()
657 tm_print_insn = print_insn_mn10200;