1 /* Target-dependent code for the Matsushita MN10300 for GDB, the GNU debugger.
2 Prologue analysis module, extracted from mn10300-tdep.c, Oct. 1, 2004.
4 Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free
5 Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
28 #include "gdb_string.h"
29 #include "trad-frame.h"
30 #include "mn10300-tdep.h"
32 enum movm_register_bits {
33 movm_exother_bit = 0x01,
34 movm_exreg1_bit = 0x02,
35 movm_exreg0_bit = 0x04,
36 movm_other_bit = 0x08,
43 /* Values for frame_info.status */
54 * status -- actually frame type (SP, FP, or last frame)
55 * stack size -- offset to the next frame
57 * The former might ultimately be stored in the frame_base.
58 * Seems like there'd be a way to store the later too.
60 * Temporarily supply empty stub functions as place holders.
64 my_frame_is_in_sp (struct frame_info *fi, void **this_cache)
66 struct trad_frame_cache *cache = mn10300_frame_unwind_cache (fi, this_cache);
67 trad_frame_set_this_base (cache,
68 frame_unwind_register_unsigned (fi,
73 my_frame_is_in_fp (struct frame_info *fi, void **this_cache)
75 struct trad_frame_cache *cache = mn10300_frame_unwind_cache (fi, this_cache);
76 trad_frame_set_this_base (cache,
77 frame_unwind_register_unsigned (fi,
82 my_frame_is_last (struct frame_info *fi)
87 is_my_frame_in_sp (struct frame_info *fi)
93 is_my_frame_in_fp (struct frame_info *fi)
99 is_my_frame_last (struct frame_info *fi)
105 set_my_stack_size (struct frame_info *fi, CORE_ADDR size)
110 /* Fix fi->frame if it's bogus at this point. This is a helper
111 function for mn10300_analyze_prologue.
113 MVS: This later became frame_base_hack, and probably now
114 could just be trad_frame_set_this_base.
118 fix_frame_pointer (struct frame_info *fi, int stack_size)
121 if (fi && get_next_frame (fi) == NULL)
123 if (is_my_frame_in_sp (fi))
124 deprecated_update_frame_base_hack (fi, read_sp () - stack_size);
125 else if (is_my_frame_in_fp (fi))
126 deprecated_update_frame_base_hack (fi, read_register (E_A3_REGNUM));
132 /* Set offsets of registers saved by movm instruction.
133 This is a helper function for mn10300_analyze_prologue. */
136 set_movm_offsets (struct frame_info *fi,
140 struct trad_frame_cache *cache;
144 if (cache == NULL || fi == NULL || movm_args == 0)
147 cache = mn10300_frame_unwind_cache (fi, this_cache);
148 base = trad_frame_get_this_base (cache);
149 if (movm_args & movm_other_bit)
151 /* The `other' bit leaves a blank area of four bytes at the
152 beginning of its block of saved registers, making it 32 bytes
154 trad_frame_set_reg_addr (cache, E_LAR_REGNUM, base + offset + 4);
155 trad_frame_set_reg_addr (cache, E_LIR_REGNUM, base + offset + 8);
156 trad_frame_set_reg_addr (cache, E_MDR_REGNUM, base + offset + 12);
157 trad_frame_set_reg_addr (cache, E_A0_REGNUM + 1, base + offset + 16);
158 trad_frame_set_reg_addr (cache, E_A0_REGNUM, base + offset + 20);
159 trad_frame_set_reg_addr (cache, E_D0_REGNUM + 1, base + offset + 24);
160 trad_frame_set_reg_addr (cache, E_D0_REGNUM, base + offset + 28);
164 if (movm_args & movm_a3_bit)
166 trad_frame_set_reg_addr (cache, E_A3_REGNUM, base + offset);
169 if (movm_args & movm_a2_bit)
171 trad_frame_set_reg_addr (cache, E_A2_REGNUM, base + offset);
174 if (movm_args & movm_d3_bit)
176 trad_frame_set_reg_addr (cache, E_D3_REGNUM, base + offset);
179 if (movm_args & movm_d2_bit)
181 trad_frame_set_reg_addr (cache, E_D2_REGNUM, base + offset);
186 if (movm_args & movm_exother_bit)
188 trad_frame_set_reg_addr (cache, E_MCVF_REGNUM, base + offset);
189 trad_frame_set_reg_addr (cache, E_MCRL_REGNUM, base + offset + 4);
190 trad_frame_set_reg_addr (cache, E_MCRH_REGNUM, base + offset + 8);
191 trad_frame_set_reg_addr (cache, E_MDRQ_REGNUM, base + offset + 12);
192 trad_frame_set_reg_addr (cache, E_E1_REGNUM, base + offset + 16);
193 trad_frame_set_reg_addr (cache, E_E0_REGNUM, base + offset + 20);
196 if (movm_args & movm_exreg1_bit)
198 trad_frame_set_reg_addr (cache, E_E7_REGNUM, base + offset);
199 trad_frame_set_reg_addr (cache, E_E6_REGNUM, base + offset + 4);
200 trad_frame_set_reg_addr (cache, E_E5_REGNUM, base + offset + 8);
201 trad_frame_set_reg_addr (cache, E_E4_REGNUM, base + offset + 12);
204 if (movm_args & movm_exreg0_bit)
206 trad_frame_set_reg_addr (cache, E_E3_REGNUM, base + offset);
207 trad_frame_set_reg_addr (cache, E_E2_REGNUM, base + offset + 4);
211 /* The last (or first) thing on the stack will be the PC. */
212 trad_frame_set_reg_addr (cache, E_PC_REGNUM, base + offset);
213 /* Save the SP in the 'traditional' way.
214 This will be the same location where the PC is saved. */
215 trad_frame_set_reg_value (cache, E_SP_REGNUM, base + offset);
218 /* The main purpose of this file is dealing with prologues to extract
219 information about stack frames and saved registers.
221 In gcc/config/mn13000/mn10300.c, the expand_prologue prologue
222 function is pretty readable, and has a nice explanation of how the
223 prologue is generated. The prologues generated by that code will
224 have the following form (NOTE: the current code doesn't handle all
227 + If this is an old-style varargs function, then its arguments
228 need to be flushed back to the stack:
233 + If we use any of the callee-saved registers, save them now.
235 movm [some callee-saved registers],(sp)
237 + If we have any floating-point registers to save:
239 - Decrement the stack pointer to reserve space for the registers.
240 If the function doesn't need a frame pointer, we may combine
241 this with the adjustment that reserves space for the frame.
245 - Save the floating-point registers. We have two possible
248 . Save them at fixed offset from the SP:
250 fmov fsN,(OFFSETN,sp)
251 fmov fsM,(OFFSETM,sp)
254 Note that, if OFFSETN happens to be zero, you'll get the
255 different opcode: fmov fsN,(sp)
257 . Or, set a0 to the start of the save area, and then use
258 post-increment addressing to save the FP registers.
266 + If the function needs a frame pointer, we set it here.
270 + Now we reserve space for the stack frame proper. This could be
271 merged into the `add -SIZE, sp' instruction for FP saves up
272 above, unless we needed to set the frame pointer in the previous
273 step, or the frame is so large that allocating the whole thing at
274 once would put the FP register save slots out of reach of the
275 addressing mode (128 bytes).
279 One day we might keep the stack pointer constant, that won't
280 change the code for prologues, but it will make the frame
281 pointerless case much more common. */
283 /* Analyze the prologue to determine where registers are saved,
284 the end of the prologue, etc etc. Return the end of the prologue
287 We store into FI (if non-null) several tidbits of information:
289 * stack_size -- size of this stack frame. Note that if we stop in
290 certain parts of the prologue/epilogue we may claim the size of the
291 current frame is zero. This happens when the current frame has
292 not been allocated yet or has already been deallocated.
294 * fsr -- Addresses of registers saved in the stack by this frame.
296 * status -- A (relatively) generic status indicator. It's a bitmask
297 with the following bits:
299 MY_FRAME_IN_SP: The base of the current frame is actually in
300 the stack pointer. This can happen for frame pointerless
301 functions, or cases where we're stopped in the prologue/epilogue
302 itself. For these cases mn10300_analyze_prologue will need up
303 update fi->frame before returning or analyzing the register
306 MY_FRAME_IN_FP: The base of the current frame is in the
307 frame pointer register ($a3).
309 NO_MORE_FRAMES: Set this if the current frame is "start" or
310 if the first instruction looks like mov <imm>,sp. This tells
311 frame chain to not bother trying to unwind past this frame. */
314 mn10300_analyze_prologue (struct frame_info *fi,
318 CORE_ADDR func_addr, func_end, addr, stop;
321 unsigned char buf[4];
322 int status, movm_args = 0;
325 /* Use the PC in the frame if it's provided to look up the
326 start of this function.
328 Note: kevinb/2003-07-16: We used to do the following here:
329 pc = (fi ? get_frame_pc (fi) : pc);
330 But this is (now) badly broken when called from analyze_dummy_frame().
332 pc = (pc ? pc : get_frame_pc (fi));
334 /* Find the start of this function. */
335 status = find_pc_partial_function (pc, &name, &func_addr, &func_end);
337 /* Do nothing if we couldn't find the start of this function or if we're
338 stopped at the first instruction in the prologue. */
344 /* If we're in start, then give up. */
345 if (strcmp (name, "start") == 0)
348 my_frame_is_last (fi);
352 /* At the start of a function our frame is in the stack pointer. */
354 my_frame_is_in_sp (fi, this_cache);
357 /* Get the next two bytes into buf, we need two because rets is a two
358 byte insn and the first isn't enough to uniquely identify it. */
359 status = deprecated_read_memory_nobpt (pc, buf, 2);
363 /* Note: kevinb/2003-07-16: We shouldn't be making these sorts of
364 changes to the frame in prologue examination code. */
365 /* If we're physically on an "rets" instruction, then our frame has
366 already been deallocated. Note this can also be true for retf
367 and ret if they specify a size of zero.
369 In this case fi->frame is bogus, we need to fix it. */
370 if (fi && buf[0] == 0xf0 && buf[1] == 0xfc)
372 if (get_next_frame (fi) == NULL)
373 deprecated_update_frame_base_hack (fi, read_sp ());
374 return get_frame_pc (fi);
377 /* Similarly if we're stopped on the first insn of a prologue as our
378 frame hasn't been allocated yet. */
379 if (fi && get_frame_pc (fi) == func_addr)
381 if (get_next_frame (fi) == NULL)
382 deprecated_update_frame_base_hack (fi, read_sp ());
383 return get_frame_pc (fi);
387 /* Figure out where to stop scanning. */
388 stop = fi ? pc : func_end;
390 /* Don't walk off the end of the function. */
391 stop = stop > func_end ? func_end : stop;
393 /* Start scanning on the first instruction of this function. */
396 /* Suck in two bytes. */
398 || (status = deprecated_read_memory_nobpt (addr, buf, 2)) != 0)
400 fix_frame_pointer (fi, 0);
404 /* First see if this insn sets the stack pointer from a register; if
405 so, it's probably the initialization of the stack pointer in _start,
406 so mark this as the bottom-most frame. */
407 if (buf[0] == 0xf2 && (buf[1] & 0xf3) == 0xf0)
410 my_frame_is_last (fi);
414 /* Now look for movm [regs],sp, which saves the callee saved registers.
416 At this time we don't know if fi->frame is valid, so we only note
417 that we encountered a movm instruction. Later, we'll set the entries
418 in fsr.regs as needed. */
421 /* Extract the register list for the movm instruction. */
426 /* Quit now if we're beyond the stop point. */
429 /* Fix fi->frame since it's bogus at this point. */
430 if (fi && get_next_frame (fi) == NULL)
431 deprecated_update_frame_base_hack (fi, read_sp ());
433 /* Note if/where callee saved registers were saved. */
434 set_movm_offsets (fi, this_cache, movm_args);
438 /* Get the next two bytes so the prologue scan can continue. */
439 status = deprecated_read_memory_nobpt (addr, buf, 2);
442 /* Fix fi->frame since it's bogus at this point. */
443 if (fi && get_next_frame (fi) == NULL)
444 deprecated_update_frame_base_hack (fi, read_sp ());
446 /* Note if/where callee saved registers were saved. */
447 set_movm_offsets (fi, this_cache, movm_args);
452 /* Now see if we set up a frame pointer via "mov sp,a3" */
457 /* The frame pointer is now valid. */
460 my_frame_is_in_fp (fi, this_cache);
463 /* Quit now if we're beyond the stop point. */
466 /* Fix fi->frame if it's bogus at this point. */
467 fix_frame_pointer (fi, 0);
469 /* Note if/where callee saved registers were saved. */
470 set_movm_offsets (fi, this_cache, movm_args);
474 /* Get two more bytes so scanning can continue. */
475 status = deprecated_read_memory_nobpt (addr, buf, 2);
478 /* Fix fi->frame if it's bogus at this point. */
479 fix_frame_pointer (fi, 0);
481 /* Note if/where callee saved registers were saved. */
482 set_movm_offsets (fi, this_cache, movm_args);
487 /* Next we should allocate the local frame. No more prologue insns
488 are found after allocating the local frame.
490 Search for add imm8,sp (0xf8feXX)
491 or add imm16,sp (0xfafeXXXX)
492 or add imm32,sp (0xfcfeXXXXXXXX).
494 If none of the above was found, then this prologue has no
498 if (buf[0] == 0xf8 && buf[1] == 0xfe)
500 else if (buf[0] == 0xfa && buf[1] == 0xfe)
502 else if (buf[0] == 0xfc && buf[1] == 0xfe)
507 /* Suck in imm_size more bytes, they'll hold the size of the
509 status = deprecated_read_memory_nobpt (addr + 2, buf, imm_size);
512 /* Fix fi->frame if it's bogus at this point. */
513 fix_frame_pointer (fi, 0);
515 /* Note if/where callee saved registers were saved. */
516 set_movm_offsets (fi, this_cache, movm_args);
520 /* Note the size of the stack in the frame info structure. */
521 stack_size = extract_signed_integer (buf, imm_size);
523 set_my_stack_size (fi, stack_size);
525 /* We just consumed 2 + imm_size bytes. */
526 addr += 2 + imm_size;
528 /* No more prologue insns follow, so begin preparation to return. */
529 /* Fix fi->frame if it's bogus at this point. */
530 fix_frame_pointer (fi, stack_size);
532 /* Note if/where callee saved registers were saved. */
533 set_movm_offsets (fi, this_cache, movm_args);
537 /* We never found an insn which allocates local stack space, regardless
538 this is the end of the prologue. */
539 /* Fix fi->frame if it's bogus at this point. */
540 fix_frame_pointer (fi, 0);
542 /* Note if/where callee saved registers were saved. */
543 set_movm_offsets (fi, this_cache, movm_args);