1 /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free Software
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. */
26 #include "dummy-frame.h"
30 #include "gdb_assert.h"
32 /* Dummy frame. This saves the processor state just prior to setting
33 up the inferior function call. Older targets save the registers
34 on the target stack (but that really slows down function calls). */
38 struct dummy_frame
*next
;
40 /* These values belong to the caller (the previous frame, the frame
41 that this unwinds back to). */
47 struct regcache
*regcache
;
49 /* Address range of the call dummy code. Look for PC in the range
50 [LO..HI) (after allowing for DECR_PC_AFTER_BREAK). */
55 static struct dummy_frame
*dummy_frame_stack
= NULL
;
57 /* Function: find_dummy_frame(pc, fp, sp)
59 Search the stack of dummy frames for one matching the given PC and
60 FP/SP. Unlike pc_in_dummy_frame(), this function doesn't need to
61 adjust for DECR_PC_AFTER_BREAK. This is because it is only legal
62 to call this function after the PC has been adjusted. */
64 static struct dummy_frame
*
65 find_dummy_frame (CORE_ADDR pc
, CORE_ADDR fp
)
67 struct dummy_frame
*dummyframe
;
69 for (dummyframe
= dummy_frame_stack
; dummyframe
!= NULL
;
70 dummyframe
= dummyframe
->next
)
72 /* Does the PC fall within the dummy frame's breakpoint
73 instruction. If not, discard this one. */
74 if (!(pc
>= dummyframe
->call_lo
&& pc
< dummyframe
->call_hi
))
76 /* Does the FP match? */
77 if (dummyframe
->top
!= 0)
79 /* If the target architecture explicitly saved the
80 top-of-stack before the inferior function call, assume
81 that that same architecture will always pass in an FP
82 (frame base) value that eactly matches that saved TOS.
83 Don't check the saved SP and SP as they can lead to false
85 if (fp
!= dummyframe
->top
)
90 /* An older target that hasn't explicitly or implicitly
91 saved the dummy frame's top-of-stack. Try matching the
92 FP against the saved SP and FP. NOTE: If you're trying
93 to fix a problem with GDB not correctly finding a dummy
94 frame, check the comments that go with FRAME_ALIGN() and
95 SAVE_DUMMY_FRAME_TOS(). */
96 if (fp
!= dummyframe
->fp
&& fp
!= dummyframe
->sp
)
99 /* The FP matches this dummy frame. */
107 cached_find_dummy_frame (struct frame_info
*frame
, void **cache
)
109 if ((*cache
) == NULL
)
110 (*cache
) = find_dummy_frame (get_frame_pc (frame
), get_frame_base (frame
));
115 generic_find_dummy_frame (CORE_ADDR pc
, CORE_ADDR fp
)
117 struct dummy_frame
*dummy
= find_dummy_frame (pc
, fp
);
119 return dummy
->regcache
;
125 deprecated_generic_find_dummy_frame (CORE_ADDR pc
, CORE_ADDR fp
)
127 struct regcache
*regcache
= generic_find_dummy_frame (pc
, fp
);
128 if (regcache
== NULL
)
130 return deprecated_grub_regcache_for_registers (regcache
);
133 /* Function: pc_in_call_dummy (pc, sp, fp)
135 Return true if the PC falls in a dummy frame created by gdb for an
136 inferior call. The code below which allows DECR_PC_AFTER_BREAK is
137 for infrun.c, which may give the function a PC without that
141 generic_pc_in_call_dummy (CORE_ADDR pc
, CORE_ADDR sp
, CORE_ADDR fp
)
143 return pc_in_dummy_frame (pc
);
146 /* Return non-zero if the PC falls in a dummy frame.
148 The code below which allows DECR_PC_AFTER_BREAK is for infrun.c,
149 which may give the function a PC without that subtracted out.
151 FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can
152 figure out what the real PC (as in the resume address) is BEFORE
153 calling this function (Oh, and I'm not even sure that this function
154 is called with an decremented PC, the call to pc_in_call_dummy() in
155 that file is conditional on !CALL_DUMMY_BREAKPOINT_OFFSET_P yet
156 generic dummy targets set CALL_DUMMY_BREAKPOINT_OFFSET. True?). */
159 pc_in_dummy_frame (CORE_ADDR pc
)
161 struct dummy_frame
*dummyframe
;
162 for (dummyframe
= dummy_frame_stack
;
164 dummyframe
= dummyframe
->next
)
166 if ((pc
>= dummyframe
->call_lo
)
167 && (pc
< dummyframe
->call_hi
+ DECR_PC_AFTER_BREAK
))
173 /* Function: read_register_dummy
174 Find a saved register from before GDB calls a function in the inferior */
177 deprecated_read_register_dummy (CORE_ADDR pc
, CORE_ADDR fp
, int regno
)
179 struct regcache
*dummy_regs
= generic_find_dummy_frame (pc
, fp
);
183 /* NOTE: cagney/2002-08-12: Replaced a call to
184 regcache_raw_read_as_address() with a call to
185 regcache_cooked_read_unsigned(). The old, ...as_address
186 function was eventually calling extract_unsigned_integer (via
187 extract_address) to unpack the registers value. The below is
188 doing an unsigned extract so that it is functionally
189 equivalent. The read needs to be cooked as, otherwise, it
190 will never correctly return the value of a register in the
191 [NUM_REGS .. NUM_REGS+NUM_PSEUDO_REGS) range. */
193 regcache_cooked_read_unsigned (dummy_regs
, regno
, &val
);
200 /* Save all the registers on the dummy frame stack. Most ports save the
201 registers on the target stack. This results in lots of unnecessary memory
202 references, which are slow when debugging via a serial line. Instead, we
203 save all the registers internally, and never write them to the stack. The
204 registers get restored when the called function returns to the entry point,
205 where a breakpoint is laying in wait. */
208 generic_push_dummy_frame (void)
210 struct dummy_frame
*dummy_frame
;
211 CORE_ADDR fp
= get_frame_base (get_current_frame ());
213 /* check to see if there are stale dummy frames,
214 perhaps left over from when a longjump took us out of a
215 function that was called by the debugger */
217 dummy_frame
= dummy_frame_stack
;
219 if (INNER_THAN (dummy_frame
->fp
, fp
)) /* stale -- destroy! */
221 dummy_frame_stack
= dummy_frame
->next
;
222 regcache_xfree (dummy_frame
->regcache
);
224 dummy_frame
= dummy_frame_stack
;
227 dummy_frame
= dummy_frame
->next
;
229 dummy_frame
= xmalloc (sizeof (struct dummy_frame
));
230 dummy_frame
->regcache
= regcache_xmalloc (current_gdbarch
);
232 dummy_frame
->pc
= read_pc ();
233 dummy_frame
->sp
= read_sp ();
234 dummy_frame
->top
= 0;
235 dummy_frame
->fp
= fp
;
236 dummy_frame
->id
= get_frame_id (get_current_frame ());
237 regcache_cpy (dummy_frame
->regcache
, current_regcache
);
238 dummy_frame
->next
= dummy_frame_stack
;
239 dummy_frame_stack
= dummy_frame
;
243 generic_save_dummy_frame_tos (CORE_ADDR sp
)
245 dummy_frame_stack
->top
= sp
;
248 /* Record the upper/lower bounds on the address of the call dummy. */
251 generic_save_call_dummy_addr (CORE_ADDR lo
, CORE_ADDR hi
)
253 dummy_frame_stack
->call_lo
= lo
;
254 dummy_frame_stack
->call_hi
= hi
;
257 /* Restore the machine state from either the saved dummy stack or a
261 generic_pop_current_frame (void (*popper
) (struct frame_info
* frame
))
263 struct frame_info
*frame
= get_current_frame ();
264 if (get_frame_type (frame
) == DUMMY_FRAME
)
265 /* NOTE: cagney/2002-22-23: Does this ever occure? Surely a dummy
266 frame will have already been poped by the "infrun.c" code. */
267 generic_pop_dummy_frame ();
272 /* Function: pop_dummy_frame
273 Restore the machine state from a saved dummy stack frame. */
276 generic_pop_dummy_frame (void)
278 struct dummy_frame
*dummy_frame
= dummy_frame_stack
;
280 /* FIXME: what if the first frame isn't the right one, eg..
281 because one call-by-hand function has done a longjmp into another one? */
284 error ("Can't pop dummy frame!");
285 dummy_frame_stack
= dummy_frame
->next
;
286 regcache_cpy (current_regcache
, dummy_frame
->regcache
);
287 flush_cached_frames ();
289 regcache_xfree (dummy_frame
->regcache
);
293 /* Function: fix_call_dummy
294 Stub function. Generic dummy frames typically do not need to fix
295 the frame being created */
298 generic_fix_call_dummy (char *dummy
, CORE_ADDR pc
, CORE_ADDR fun
, int nargs
,
299 struct value
**args
, struct type
*type
, int gcc_p
)
304 /* Given a call-dummy dummy-frame, return the registers. Here the
305 register value is taken from the local copy of the register buffer. */
308 dummy_frame_register_unwind (struct frame_info
*frame
, void **cache
,
309 int regnum
, int *optimized
,
310 enum lval_type
*lvalp
, CORE_ADDR
*addrp
,
311 int *realnum
, void *bufferp
)
313 struct dummy_frame
*dummy
= cached_find_dummy_frame (frame
, cache
);
314 gdb_assert (dummy
!= NULL
);
316 /* Describe the register's location. Generic dummy frames always
317 have the register value in an ``expression''. */
323 /* If needed, find and return the value of the register. */
326 /* Return the actual value. */
327 /* Use the regcache_cooked_read() method so that it, on the fly,
328 constructs either a raw or pseudo register from the raw
330 regcache_cooked_read (dummy
->regcache
, regnum
, bufferp
);
335 dummy_frame_pc_unwind (struct frame_info
*frame
,
338 struct dummy_frame
*dummy
= cached_find_dummy_frame (frame
, cache
);
339 /* Oops! In a dummy-frame but can't find the stack dummy. Pretend
340 that the frame doesn't unwind. Should this function instead
341 return a has-no-caller indication? */
349 dummy_frame_id_unwind (struct frame_info
*frame
,
352 struct dummy_frame
*dummy
= cached_find_dummy_frame (frame
, cache
);
353 /* Oops! In a dummy-frame but can't find the stack dummy. Pretend
354 that the frame doesn't unwind. Should this function instead
355 return a has-no-caller indication? */
357 return null_frame_id
;
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