1 /* Find a variable's value in memory, for GDB, the GNU debugger.
3 Copyright (C) 1986-2017 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
28 #include "floatformat.h"
29 #include "symfile.h" /* for overlay functions */
31 #include "user-regs.h"
35 #include "dwarf2loc.h"
37 /* Basic byte-swapping routines. All 'extract' functions return a
38 host-format integer from a target-format integer at ADDR which is
41 #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8
42 /* 8 bit characters are a pretty safe assumption these days, so we
43 assume it throughout all these swapping routines. If we had to deal with
44 9 bit characters, we would need to make len be in bits and would have
45 to re-write these routines... */
50 extract_signed_integer (const gdb_byte
*addr
, int len
,
51 enum bfd_endian byte_order
)
54 const unsigned char *p
;
55 const unsigned char *startaddr
= addr
;
56 const unsigned char *endaddr
= startaddr
+ len
;
58 if (len
> (int) sizeof (LONGEST
))
60 That operation is not available on integers of more than %d bytes."),
61 (int) sizeof (LONGEST
));
63 /* Start at the most significant end of the integer, and work towards
64 the least significant. */
65 if (byte_order
== BFD_ENDIAN_BIG
)
68 /* Do the sign extension once at the start. */
69 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
70 for (++p
; p
< endaddr
; ++p
)
71 retval
= (retval
<< 8) | *p
;
76 /* Do the sign extension once at the start. */
77 retval
= ((LONGEST
) * p
^ 0x80) - 0x80;
78 for (--p
; p
>= startaddr
; --p
)
79 retval
= (retval
<< 8) | *p
;
85 extract_unsigned_integer (const gdb_byte
*addr
, int len
,
86 enum bfd_endian byte_order
)
89 const unsigned char *p
;
90 const unsigned char *startaddr
= addr
;
91 const unsigned char *endaddr
= startaddr
+ len
;
93 if (len
> (int) sizeof (ULONGEST
))
95 That operation is not available on integers of more than %d bytes."),
96 (int) sizeof (ULONGEST
));
98 /* Start at the most significant end of the integer, and work towards
99 the least significant. */
101 if (byte_order
== BFD_ENDIAN_BIG
)
103 for (p
= startaddr
; p
< endaddr
; ++p
)
104 retval
= (retval
<< 8) | *p
;
108 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
109 retval
= (retval
<< 8) | *p
;
114 /* Sometimes a long long unsigned integer can be extracted as a
115 LONGEST value. This is done so that we can print these values
116 better. If this integer can be converted to a LONGEST, this
117 function returns 1 and sets *PVAL. Otherwise it returns 0. */
120 extract_long_unsigned_integer (const gdb_byte
*addr
, int orig_len
,
121 enum bfd_endian byte_order
, LONGEST
*pval
)
124 const gdb_byte
*first_addr
;
128 if (byte_order
== BFD_ENDIAN_BIG
)
131 len
> (int) sizeof (LONGEST
) && p
< addr
+ orig_len
;
144 for (p
= addr
+ orig_len
- 1;
145 len
> (int) sizeof (LONGEST
) && p
>= addr
;
155 if (len
<= (int) sizeof (LONGEST
))
157 *pval
= (LONGEST
) extract_unsigned_integer (first_addr
,
167 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
168 address it represents. */
170 extract_typed_address (const gdb_byte
*buf
, struct type
*type
)
172 if (TYPE_CODE (type
) != TYPE_CODE_PTR
&& !TYPE_IS_REFERENCE (type
))
173 internal_error (__FILE__
, __LINE__
,
174 _("extract_typed_address: "
175 "type is not a pointer or reference"));
177 return gdbarch_pointer_to_address (get_type_arch (type
), type
, buf
);
180 /* All 'store' functions accept a host-format integer and store a
181 target-format integer at ADDR which is LEN bytes long. */
184 store_signed_integer (gdb_byte
*addr
, int len
,
185 enum bfd_endian byte_order
, LONGEST val
)
188 gdb_byte
*startaddr
= addr
;
189 gdb_byte
*endaddr
= startaddr
+ len
;
191 /* Start at the least significant end of the integer, and work towards
192 the most significant. */
193 if (byte_order
== BFD_ENDIAN_BIG
)
195 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
203 for (p
= startaddr
; p
< endaddr
; ++p
)
212 store_unsigned_integer (gdb_byte
*addr
, int len
,
213 enum bfd_endian byte_order
, ULONGEST val
)
216 unsigned char *startaddr
= (unsigned char *) addr
;
217 unsigned char *endaddr
= startaddr
+ len
;
219 /* Start at the least significant end of the integer, and work towards
220 the most significant. */
221 if (byte_order
== BFD_ENDIAN_BIG
)
223 for (p
= endaddr
- 1; p
>= startaddr
; --p
)
231 for (p
= startaddr
; p
< endaddr
; ++p
)
239 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
242 store_typed_address (gdb_byte
*buf
, struct type
*type
, CORE_ADDR addr
)
244 if (TYPE_CODE (type
) != TYPE_CODE_PTR
&& !TYPE_IS_REFERENCE (type
))
245 internal_error (__FILE__
, __LINE__
,
246 _("store_typed_address: "
247 "type is not a pointer or reference"));
249 gdbarch_address_to_pointer (get_type_arch (type
), type
, buf
, addr
);
254 /* Return a `value' with the contents of (virtual or cooked) register
255 REGNUM as found in the specified FRAME. The register's type is
256 determined by register_type(). */
259 value_of_register (int regnum
, struct frame_info
*frame
)
261 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
262 struct value
*reg_val
;
264 /* User registers lie completely outside of the range of normal
265 registers. Catch them early so that the target never sees them. */
266 if (regnum
>= gdbarch_num_regs (gdbarch
)
267 + gdbarch_num_pseudo_regs (gdbarch
))
268 return value_of_user_reg (regnum
, frame
);
270 reg_val
= value_of_register_lazy (frame
, regnum
);
271 value_fetch_lazy (reg_val
);
275 /* Return a `value' with the contents of (virtual or cooked) register
276 REGNUM as found in the specified FRAME. The register's type is
277 determined by register_type(). The value is not fetched. */
280 value_of_register_lazy (struct frame_info
*frame
, int regnum
)
282 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
283 struct value
*reg_val
;
284 struct frame_info
*next_frame
;
286 gdb_assert (regnum
< (gdbarch_num_regs (gdbarch
)
287 + gdbarch_num_pseudo_regs (gdbarch
)));
289 gdb_assert (frame
!= NULL
);
291 next_frame
= get_next_frame_sentinel_okay (frame
);
293 /* We should have a valid next frame. */
294 gdb_assert (frame_id_p (get_frame_id (next_frame
)));
296 reg_val
= allocate_value_lazy (register_type (gdbarch
, regnum
));
297 VALUE_LVAL (reg_val
) = lval_register
;
298 VALUE_REGNUM (reg_val
) = regnum
;
299 VALUE_NEXT_FRAME_ID (reg_val
) = get_frame_id (next_frame
);
304 /* Given a pointer of type TYPE in target form in BUF, return the
305 address it represents. */
307 unsigned_pointer_to_address (struct gdbarch
*gdbarch
,
308 struct type
*type
, const gdb_byte
*buf
)
310 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
312 return extract_unsigned_integer (buf
, TYPE_LENGTH (type
), byte_order
);
316 signed_pointer_to_address (struct gdbarch
*gdbarch
,
317 struct type
*type
, const gdb_byte
*buf
)
319 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
321 return extract_signed_integer (buf
, TYPE_LENGTH (type
), byte_order
);
324 /* Given an address, store it as a pointer of type TYPE in target
327 unsigned_address_to_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
328 gdb_byte
*buf
, CORE_ADDR addr
)
330 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
332 store_unsigned_integer (buf
, TYPE_LENGTH (type
), byte_order
, addr
);
336 address_to_signed_pointer (struct gdbarch
*gdbarch
, struct type
*type
,
337 gdb_byte
*buf
, CORE_ADDR addr
)
339 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
341 store_signed_integer (buf
, TYPE_LENGTH (type
), byte_order
, addr
);
346 enum symbol_needs_kind
347 symbol_read_needs (struct symbol
*sym
)
349 if (SYMBOL_COMPUTED_OPS (sym
) != NULL
)
350 return SYMBOL_COMPUTED_OPS (sym
)->get_symbol_read_needs (sym
);
352 switch (SYMBOL_CLASS (sym
))
354 /* All cases listed explicitly so that gcc -Wall will detect it if
355 we failed to consider one. */
357 gdb_assert_not_reached (_("LOC_COMPUTED variable missing a method"));
362 case LOC_REGPARM_ADDR
:
364 return SYMBOL_NEEDS_FRAME
;
372 /* Getting the address of a label can be done independently of the block,
373 even if some *uses* of that address wouldn't work so well without
377 case LOC_CONST_BYTES
:
379 case LOC_OPTIMIZED_OUT
:
380 return SYMBOL_NEEDS_NONE
;
382 return SYMBOL_NEEDS_FRAME
;
388 symbol_read_needs_frame (struct symbol
*sym
)
390 return symbol_read_needs (sym
) == SYMBOL_NEEDS_FRAME
;
393 /* Private data to be used with minsym_lookup_iterator_cb. */
395 struct minsym_lookup_data
397 /* The name of the minimal symbol we are searching for. */
400 /* The field where the callback should store the minimal symbol
401 if found. It should be initialized to NULL before the search
403 struct bound_minimal_symbol result
;
406 /* A callback function for gdbarch_iterate_over_objfiles_in_search_order.
407 It searches by name for a minimal symbol within the given OBJFILE.
408 The arguments are passed via CB_DATA, which in reality is a pointer
409 to struct minsym_lookup_data. */
412 minsym_lookup_iterator_cb (struct objfile
*objfile
, void *cb_data
)
414 struct minsym_lookup_data
*data
= (struct minsym_lookup_data
*) cb_data
;
416 gdb_assert (data
->result
.minsym
== NULL
);
418 data
->result
= lookup_minimal_symbol (data
->name
, NULL
, objfile
);
420 /* The iterator should stop iff a match was found. */
421 return (data
->result
.minsym
!= NULL
);
424 /* Given static link expression and the frame it lives in, look for the frame
425 the static links points to and return it. Return NULL if we could not find
428 static struct frame_info
*
429 follow_static_link (struct frame_info
*frame
,
430 const struct dynamic_prop
*static_link
)
432 CORE_ADDR upper_frame_base
;
434 if (!dwarf2_evaluate_property (static_link
, frame
, NULL
, &upper_frame_base
))
437 /* Now climb up the stack frame until we reach the frame we are interested
439 for (; frame
!= NULL
; frame
= get_prev_frame (frame
))
441 struct symbol
*framefunc
= get_frame_function (frame
);
443 /* Stacks can be quite deep: give the user a chance to stop this. */
446 /* If we don't know how to compute FRAME's base address, don't give up:
447 maybe the frame we are looking for is upper in the stace frame. */
448 if (framefunc
!= NULL
449 && SYMBOL_BLOCK_OPS (framefunc
) != NULL
450 && SYMBOL_BLOCK_OPS (framefunc
)->get_frame_base
!= NULL
451 && (SYMBOL_BLOCK_OPS (framefunc
)->get_frame_base (framefunc
, frame
)
452 == upper_frame_base
))
459 /* Assuming VAR is a symbol that can be reached from FRAME thanks to lexical
460 rules, look for the frame that is actually hosting VAR and return it. If,
461 for some reason, we found no such frame, return NULL.
463 This kind of computation is necessary to correctly handle lexically nested
466 Note that in some cases, we know what scope VAR comes from but we cannot
467 reach the specific frame that hosts the instance of VAR we are looking for.
468 For backward compatibility purposes (with old compilers), we then look for
469 the first frame that can host it. */
471 static struct frame_info
*
472 get_hosting_frame (struct symbol
*var
, const struct block
*var_block
,
473 struct frame_info
*frame
)
475 const struct block
*frame_block
= NULL
;
477 if (!symbol_read_needs_frame (var
))
480 /* Some symbols for local variables have no block: this happens when they are
481 not produced by a debug information reader, for instance when GDB creates
482 synthetic symbols. Without block information, we must assume they are
483 local to FRAME. In this case, there is nothing to do. */
484 else if (var_block
== NULL
)
487 /* We currently assume that all symbols with a location list need a frame.
488 This is true in practice because selecting the location description
489 requires to compute the CFA, hence requires a frame. However we have
490 tests that embed global/static symbols with null location lists.
491 We want to get <optimized out> instead of <frame required> when evaluating
492 them so return a frame instead of raising an error. */
493 else if (var_block
== block_global_block (var_block
)
494 || var_block
== block_static_block (var_block
))
497 /* We have to handle the "my_func::my_local_var" notation. This requires us
498 to look for upper frames when we find no block for the current frame: here
499 and below, handle when frame_block == NULL. */
501 frame_block
= get_frame_block (frame
, NULL
);
503 /* Climb up the call stack until reaching the frame we are looking for. */
504 while (frame
!= NULL
&& frame_block
!= var_block
)
506 /* Stacks can be quite deep: give the user a chance to stop this. */
509 if (frame_block
== NULL
)
511 frame
= get_prev_frame (frame
);
514 frame_block
= get_frame_block (frame
, NULL
);
517 /* If we failed to find the proper frame, fallback to the heuristic
519 else if (frame_block
== block_global_block (frame_block
))
525 /* Assuming we have a block for this frame: if we are at the function
526 level, the immediate upper lexical block is in an outer function:
527 follow the static link. */
528 else if (BLOCK_FUNCTION (frame_block
))
530 const struct dynamic_prop
*static_link
531 = block_static_link (frame_block
);
532 int could_climb_up
= 0;
534 if (static_link
!= NULL
)
536 frame
= follow_static_link (frame
, static_link
);
539 frame_block
= get_frame_block (frame
, NULL
);
540 could_climb_up
= frame_block
!= NULL
;
551 /* We must be in some function nested lexical block. Just get the
552 outer block: both must share the same frame. */
553 frame_block
= BLOCK_SUPERBLOCK (frame_block
);
556 /* Old compilers may not provide a static link, or they may provide an
557 invalid one. For such cases, fallback on the old way to evaluate
558 non-local references: just climb up the call stack and pick the first
559 frame that contains the variable we are looking for. */
562 frame
= block_innermost_frame (var_block
);
565 if (BLOCK_FUNCTION (var_block
)
566 && !block_inlined_p (var_block
)
567 && SYMBOL_PRINT_NAME (BLOCK_FUNCTION (var_block
)))
568 error (_("No frame is currently executing in block %s."),
569 SYMBOL_PRINT_NAME (BLOCK_FUNCTION (var_block
)));
571 error (_("No frame is currently executing in specified"
579 /* A default implementation for the "la_read_var_value" hook in
580 the language vector which should work in most situations. */
583 default_read_var_value (struct symbol
*var
, const struct block
*var_block
,
584 struct frame_info
*frame
)
587 struct type
*type
= SYMBOL_TYPE (var
);
589 enum symbol_needs_kind sym_need
;
591 /* Call check_typedef on our type to make sure that, if TYPE is
592 a TYPE_CODE_TYPEDEF, its length is set to the length of the target type
593 instead of zero. However, we do not replace the typedef type by the
594 target type, because we want to keep the typedef in order to be able to
595 set the returned value type description correctly. */
596 check_typedef (type
);
598 sym_need
= symbol_read_needs (var
);
599 if (sym_need
== SYMBOL_NEEDS_FRAME
)
600 gdb_assert (frame
!= NULL
);
601 else if (sym_need
== SYMBOL_NEEDS_REGISTERS
&& !target_has_registers
)
602 error (_("Cannot read `%s' without registers"), SYMBOL_PRINT_NAME (var
));
605 frame
= get_hosting_frame (var
, var_block
, frame
);
607 if (SYMBOL_COMPUTED_OPS (var
) != NULL
)
608 return SYMBOL_COMPUTED_OPS (var
)->read_variable (var
, frame
);
610 switch (SYMBOL_CLASS (var
))
613 if (is_dynamic_type (type
))
615 /* Value is a constant byte-sequence and needs no memory access. */
616 type
= resolve_dynamic_type (type
, NULL
, /* Unused address. */ 0);
618 /* Put the constant back in target format. */
619 v
= allocate_value (type
);
620 store_signed_integer (value_contents_raw (v
), TYPE_LENGTH (type
),
621 gdbarch_byte_order (get_type_arch (type
)),
622 (LONGEST
) SYMBOL_VALUE (var
));
623 VALUE_LVAL (v
) = not_lval
;
627 /* Put the constant back in target format. */
628 v
= allocate_value (type
);
629 if (overlay_debugging
)
632 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
633 SYMBOL_OBJ_SECTION (symbol_objfile (var
),
636 store_typed_address (value_contents_raw (v
), type
, addr
);
639 store_typed_address (value_contents_raw (v
), type
,
640 SYMBOL_VALUE_ADDRESS (var
));
641 VALUE_LVAL (v
) = not_lval
;
644 case LOC_CONST_BYTES
:
645 if (is_dynamic_type (type
))
647 /* Value is a constant byte-sequence and needs no memory access. */
648 type
= resolve_dynamic_type (type
, NULL
, /* Unused address. */ 0);
650 v
= allocate_value (type
);
651 memcpy (value_contents_raw (v
), SYMBOL_VALUE_BYTES (var
),
653 VALUE_LVAL (v
) = not_lval
;
657 if (overlay_debugging
)
658 addr
= symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var
),
659 SYMBOL_OBJ_SECTION (symbol_objfile (var
),
662 addr
= SYMBOL_VALUE_ADDRESS (var
);
666 addr
= get_frame_args_address (frame
);
668 error (_("Unknown argument list address for `%s'."),
669 SYMBOL_PRINT_NAME (var
));
670 addr
+= SYMBOL_VALUE (var
);
678 argref
= get_frame_args_address (frame
);
680 error (_("Unknown argument list address for `%s'."),
681 SYMBOL_PRINT_NAME (var
));
682 argref
+= SYMBOL_VALUE (var
);
683 ref
= value_at (lookup_pointer_type (type
), argref
);
684 addr
= value_as_address (ref
);
689 addr
= get_frame_locals_address (frame
);
690 addr
+= SYMBOL_VALUE (var
);
694 error (_("Cannot look up value of a typedef `%s'."),
695 SYMBOL_PRINT_NAME (var
));
699 if (overlay_debugging
)
700 addr
= symbol_overlayed_address
701 (BLOCK_START (SYMBOL_BLOCK_VALUE (var
)),
702 SYMBOL_OBJ_SECTION (symbol_objfile (var
), var
));
704 addr
= BLOCK_START (SYMBOL_BLOCK_VALUE (var
));
708 case LOC_REGPARM_ADDR
:
710 int regno
= SYMBOL_REGISTER_OPS (var
)
711 ->register_number (var
, get_frame_arch (frame
));
712 struct value
*regval
;
714 if (SYMBOL_CLASS (var
) == LOC_REGPARM_ADDR
)
716 regval
= value_from_register (lookup_pointer_type (type
),
721 error (_("Value of register variable not available for `%s'."),
722 SYMBOL_PRINT_NAME (var
));
724 addr
= value_as_address (regval
);
728 regval
= value_from_register (type
, regno
, frame
);
731 error (_("Value of register variable not available for `%s'."),
732 SYMBOL_PRINT_NAME (var
));
739 gdb_assert_not_reached (_("LOC_COMPUTED variable missing a method"));
743 struct minsym_lookup_data lookup_data
;
744 struct minimal_symbol
*msym
;
745 struct obj_section
*obj_section
;
747 memset (&lookup_data
, 0, sizeof (lookup_data
));
748 lookup_data
.name
= SYMBOL_LINKAGE_NAME (var
);
750 gdbarch_iterate_over_objfiles_in_search_order
752 minsym_lookup_iterator_cb
, &lookup_data
,
753 symbol_objfile (var
));
754 msym
= lookup_data
.result
.minsym
;
756 /* If we can't find the minsym there's a problem in the symbol info.
757 The symbol exists in the debug info, but it's missing in the minsym
761 const char *flavour_name
762 = objfile_flavour_name (symbol_objfile (var
));
764 /* We can't get here unless we've opened the file, so flavour_name
766 gdb_assert (flavour_name
!= NULL
);
767 error (_("Missing %s symbol \"%s\"."),
768 flavour_name
, SYMBOL_LINKAGE_NAME (var
));
770 obj_section
= MSYMBOL_OBJ_SECTION (lookup_data
.result
.objfile
, msym
);
771 /* Relocate address, unless there is no section or the variable is
773 if (obj_section
== NULL
774 || (obj_section
->the_bfd_section
->flags
& SEC_THREAD_LOCAL
) != 0)
775 addr
= MSYMBOL_VALUE_RAW_ADDRESS (msym
);
777 addr
= BMSYMBOL_VALUE_ADDRESS (lookup_data
.result
);
778 if (overlay_debugging
)
779 addr
= symbol_overlayed_address (addr
, obj_section
);
780 /* Determine address of TLS variable. */
782 && (obj_section
->the_bfd_section
->flags
& SEC_THREAD_LOCAL
) != 0)
783 addr
= target_translate_tls_address (obj_section
->objfile
, addr
);
787 case LOC_OPTIMIZED_OUT
:
788 return allocate_optimized_out_value (type
);
791 error (_("Cannot look up value of a botched symbol `%s'."),
792 SYMBOL_PRINT_NAME (var
));
796 v
= value_at_lazy (type
, addr
);
800 /* Calls VAR's language la_read_var_value hook with the given arguments. */
803 read_var_value (struct symbol
*var
, const struct block
*var_block
,
804 struct frame_info
*frame
)
806 const struct language_defn
*lang
= language_def (SYMBOL_LANGUAGE (var
));
808 gdb_assert (lang
!= NULL
);
809 gdb_assert (lang
->la_read_var_value
!= NULL
);
811 return lang
->la_read_var_value (var
, var_block
, frame
);
814 /* Install default attributes for register values. */
817 default_value_from_register (struct gdbarch
*gdbarch
, struct type
*type
,
818 int regnum
, struct frame_id frame_id
)
820 int len
= TYPE_LENGTH (type
);
821 struct value
*value
= allocate_value (type
);
822 struct frame_info
*frame
;
824 VALUE_LVAL (value
) = lval_register
;
825 frame
= frame_find_by_id (frame_id
);
828 frame_id
= null_frame_id
;
830 frame_id
= get_frame_id (get_next_frame_sentinel_okay (frame
));
832 VALUE_NEXT_FRAME_ID (value
) = frame_id
;
833 VALUE_REGNUM (value
) = regnum
;
835 /* Any structure stored in more than one register will always be
836 an integral number of registers. Otherwise, you need to do
837 some fiddling with the last register copied here for little
839 if (gdbarch_byte_order (gdbarch
) == BFD_ENDIAN_BIG
840 && len
< register_size (gdbarch
, regnum
))
841 /* Big-endian, and we want less than full size. */
842 set_value_offset (value
, register_size (gdbarch
, regnum
) - len
);
844 set_value_offset (value
, 0);
849 /* VALUE must be an lval_register value. If regnum is the value's
850 associated register number, and len the length of the values type,
851 read one or more registers in FRAME, starting with register REGNUM,
852 until we've read LEN bytes.
854 If any of the registers we try to read are optimized out, then mark the
855 complete resulting value as optimized out. */
858 read_frame_register_value (struct value
*value
, struct frame_info
*frame
)
860 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
862 LONGEST reg_offset
= value_offset (value
);
863 int regnum
= VALUE_REGNUM (value
);
864 int len
= type_length_units (check_typedef (value_type (value
)));
866 gdb_assert (VALUE_LVAL (value
) == lval_register
);
868 /* Skip registers wholly inside of REG_OFFSET. */
869 while (reg_offset
>= register_size (gdbarch
, regnum
))
871 reg_offset
-= register_size (gdbarch
, regnum
);
878 struct value
*regval
= get_frame_register_value (frame
, regnum
);
879 int reg_len
= type_length_units (value_type (regval
)) - reg_offset
;
881 /* If the register length is larger than the number of bytes
882 remaining to copy, then only copy the appropriate bytes. */
886 value_contents_copy (value
, offset
, regval
, reg_offset
, reg_len
);
895 /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */
898 value_from_register (struct type
*type
, int regnum
, struct frame_info
*frame
)
900 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
901 struct type
*type1
= check_typedef (type
);
904 if (gdbarch_convert_register_p (gdbarch
, regnum
, type1
))
906 int optim
, unavail
, ok
;
908 /* The ISA/ABI need to something weird when obtaining the
909 specified value from this register. It might need to
910 re-order non-adjacent, starting with REGNUM (see MIPS and
911 i386). It might need to convert the [float] register into
912 the corresponding [integer] type (see Alpha). The assumption
913 is that gdbarch_register_to_value populates the entire value
914 including the location. */
915 v
= allocate_value (type
);
916 VALUE_LVAL (v
) = lval_register
;
917 VALUE_NEXT_FRAME_ID (v
) = get_frame_id (get_next_frame_sentinel_okay (frame
));
918 VALUE_REGNUM (v
) = regnum
;
919 ok
= gdbarch_register_to_value (gdbarch
, frame
, regnum
, type1
,
920 value_contents_raw (v
), &optim
,
926 mark_value_bytes_optimized_out (v
, 0, TYPE_LENGTH (type
));
928 mark_value_bytes_unavailable (v
, 0, TYPE_LENGTH (type
));
933 /* Construct the value. */
934 v
= gdbarch_value_from_register (gdbarch
, type
,
935 regnum
, get_frame_id (frame
));
938 read_frame_register_value (v
, frame
);
944 /* Return contents of register REGNUM in frame FRAME as address.
945 Will abort if register value is not available. */
948 address_from_register (int regnum
, struct frame_info
*frame
)
950 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
951 struct type
*type
= builtin_type (gdbarch
)->builtin_data_ptr
;
954 int regnum_max_excl
= (gdbarch_num_regs (gdbarch
)
955 + gdbarch_num_pseudo_regs (gdbarch
));
957 if (regnum
< 0 || regnum
>= regnum_max_excl
)
958 error (_("Invalid register #%d, expecting 0 <= # < %d"), regnum
,
961 /* This routine may be called during early unwinding, at a time
962 where the ID of FRAME is not yet known. Calling value_from_register
963 would therefore abort in get_frame_id. However, since we only need
964 a temporary value that is never used as lvalue, we actually do not
965 really need to set its VALUE_NEXT_FRAME_ID. Therefore, we re-implement
966 the core of value_from_register, but use the null_frame_id. */
968 /* Some targets require a special conversion routine even for plain
969 pointer types. Avoid constructing a value object in those cases. */
970 if (gdbarch_convert_register_p (gdbarch
, regnum
, type
))
972 gdb_byte
*buf
= (gdb_byte
*) alloca (TYPE_LENGTH (type
));
973 int optim
, unavail
, ok
;
975 ok
= gdbarch_register_to_value (gdbarch
, frame
, regnum
, type
,
976 buf
, &optim
, &unavail
);
979 /* This function is used while computing a location expression.
980 Complain about the value being optimized out, rather than
981 letting value_as_address complain about some random register
982 the expression depends on not being saved. */
983 error_value_optimized_out ();
986 return unpack_long (type
, buf
);
989 value
= gdbarch_value_from_register (gdbarch
, type
, regnum
, null_frame_id
);
990 read_frame_register_value (value
, frame
);
992 if (value_optimized_out (value
))
994 /* This function is used while computing a location expression.
995 Complain about the value being optimized out, rather than
996 letting value_as_address complain about some random register
997 the expression depends on not being saved. */
998 error_value_optimized_out ();
1001 result
= value_as_address (value
);
1002 release_value (value
);