1 /* Find a variable's value in memory, for GDB, the GNU debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003 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. */
32 #include "gdb_string.h"
33 #include "gdb_assert.h"
34 #include "floatformat.h"
35 #include "symfile.h" /* for overlay functions */
37 #include "user-regs.h"
40 /* Basic byte-swapping routines. GDB has needed these for a long time...
41 All extract a target-format integer at ADDR which is LEN bytes long. */
43 #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8
44 /* 8 bit characters are a pretty safe assumption these days, so we
45 assume it throughout all these swapping routines. If we had to deal with
46 9 bit characters, we would need to make len be in bits and would have
47 to re-write these routines... */
52 extract_signed_integer (const void *addr, int len)
55 const unsigned char *p;
56 const unsigned char *startaddr = addr;
57 const unsigned char *endaddr = startaddr + len;
59 if (len > (int) sizeof (LONGEST))
61 That operation is not available on integers of more than %d bytes.",
62 (int) sizeof (LONGEST));
64 /* Start at the most significant end of the integer, and work towards
65 the least significant. */
66 if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
69 /* Do the sign extension once at the start. */
70 retval = ((LONGEST) * p ^ 0x80) - 0x80;
71 for (++p; p < endaddr; ++p)
72 retval = (retval << 8) | *p;
77 /* Do the sign extension once at the start. */
78 retval = ((LONGEST) * p ^ 0x80) - 0x80;
79 for (--p; p >= startaddr; --p)
80 retval = (retval << 8) | *p;
86 extract_unsigned_integer (const void *addr, int len)
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 (TARGET_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 void *addr, int orig_len, LONGEST *pval)
122 char *p, *first_addr;
126 if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
128 for (p = (char *) addr;
129 len > (int) sizeof (LONGEST) && p < (char *) addr + orig_len;
141 first_addr = (char *) addr;
142 for (p = (char *) addr + orig_len - 1;
143 len > (int) sizeof (LONGEST) && p >= (char *) addr;
153 if (len <= (int) sizeof (LONGEST))
155 *pval = (LONGEST) extract_unsigned_integer (first_addr,
164 /* Treat the bytes at BUF as a pointer of type TYPE, and return the
165 address it represents. */
167 extract_typed_address (const void *buf, struct type *type)
169 if (TYPE_CODE (type) != TYPE_CODE_PTR
170 && TYPE_CODE (type) != TYPE_CODE_REF)
171 internal_error (__FILE__, __LINE__,
172 "extract_typed_address: "
173 "type is not a pointer or reference");
175 return POINTER_TO_ADDRESS (type, buf);
180 store_signed_integer (void *addr, int len, LONGEST val)
183 unsigned char *startaddr = (unsigned char *) addr;
184 unsigned char *endaddr = startaddr + len;
186 /* Start at the least significant end of the integer, and work towards
187 the most significant. */
188 if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
190 for (p = endaddr - 1; p >= startaddr; --p)
198 for (p = startaddr; p < endaddr; ++p)
207 store_unsigned_integer (void *addr, int len, ULONGEST val)
210 unsigned char *startaddr = (unsigned char *) addr;
211 unsigned char *endaddr = startaddr + len;
213 /* Start at the least significant end of the integer, and work towards
214 the most significant. */
215 if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
217 for (p = endaddr - 1; p >= startaddr; --p)
225 for (p = startaddr; p < endaddr; ++p)
233 /* Store the address ADDR as a pointer of type TYPE at BUF, in target
236 store_typed_address (void *buf, struct type *type, CORE_ADDR addr)
238 if (TYPE_CODE (type) != TYPE_CODE_PTR
239 && TYPE_CODE (type) != TYPE_CODE_REF)
240 internal_error (__FILE__, __LINE__,
241 "store_typed_address: "
242 "type is not a pointer or reference");
244 ADDRESS_TO_POINTER (type, buf, addr);
249 /* Return a `value' with the contents of (virtual or cooked) register
250 REGNUM as found in the specified FRAME. The register's type is
251 determined by register_type().
253 NOTE: returns NULL if register value is not available. Caller will
254 check return value or die! */
257 value_of_register (int regnum, struct frame_info *frame)
261 struct value *reg_val;
263 char raw_buffer[MAX_REGISTER_SIZE];
266 /* User registers lie completly outside of the range of normal
267 registers. Catch them early so that the target never sees them. */
268 if (regnum >= NUM_REGS + NUM_PSEUDO_REGS)
269 return value_of_user_reg (regnum, frame);
271 frame_register (frame, regnum, &optim, &lval, &addr, &realnum, raw_buffer);
273 /* FIXME: cagney/2002-05-15: This test is just bogus.
275 It indicates that the target failed to supply a value for a
276 register because it was "not available" at this time. Problem
277 is, the target still has the register and so get saved_register()
278 may be returning a value saved on the stack. */
280 if (register_cached (regnum) < 0)
281 return NULL; /* register value not available */
283 reg_val = allocate_value (register_type (current_gdbarch, regnum));
285 /* Convert raw data to virtual format if necessary. */
287 if (DEPRECATED_REGISTER_CONVERTIBLE (regnum))
289 DEPRECATED_REGISTER_CONVERT_TO_VIRTUAL (regnum, register_type (current_gdbarch, regnum),
290 raw_buffer, VALUE_CONTENTS_RAW (reg_val));
292 else if (REGISTER_RAW_SIZE (regnum) == REGISTER_VIRTUAL_SIZE (regnum))
293 memcpy (VALUE_CONTENTS_RAW (reg_val), raw_buffer,
294 REGISTER_RAW_SIZE (regnum));
296 internal_error (__FILE__, __LINE__,
297 "Register \"%s\" (%d) has conflicting raw (%d) and virtual (%d) size",
298 REGISTER_NAME (regnum),
300 REGISTER_RAW_SIZE (regnum),
301 REGISTER_VIRTUAL_SIZE (regnum));
302 VALUE_LVAL (reg_val) = lval;
303 VALUE_ADDRESS (reg_val) = addr;
304 VALUE_REGNO (reg_val) = regnum;
305 VALUE_OPTIMIZED_OUT (reg_val) = optim;
309 /* Given a pointer of type TYPE in target form in BUF, return the
310 address it represents. */
312 unsigned_pointer_to_address (struct type *type, const void *buf)
314 return extract_unsigned_integer (buf, TYPE_LENGTH (type));
318 signed_pointer_to_address (struct type *type, const void *buf)
320 return extract_signed_integer (buf, TYPE_LENGTH (type));
323 /* Given an address, store it as a pointer of type TYPE in target
326 unsigned_address_to_pointer (struct type *type, void *buf, CORE_ADDR addr)
328 store_unsigned_integer (buf, TYPE_LENGTH (type), addr);
332 address_to_signed_pointer (struct type *type, void *buf, CORE_ADDR addr)
334 store_signed_integer (buf, TYPE_LENGTH (type), addr);
337 /* Will calling read_var_value or locate_var_value on SYM end
338 up caring what frame it is being evaluated relative to? SYM must
341 symbol_read_needs_frame (struct symbol *sym)
343 switch (SYMBOL_CLASS (sym))
345 /* All cases listed explicitly so that gcc -Wall will detect it if
346 we failed to consider one. */
348 case LOC_COMPUTED_ARG:
350 struct location_funcs *symfuncs = SYMBOL_LOCATION_FUNCS (sym);
351 return (symfuncs->read_needs_frame) (sym);
359 case LOC_REGPARM_ADDR:
363 case LOC_BASEREG_ARG:
364 case LOC_HP_THREAD_LOCAL_STATIC:
374 /* Getting the address of a label can be done independently of the block,
375 even if some *uses* of that address wouldn't work so well without
379 case LOC_CONST_BYTES:
381 case LOC_OPTIMIZED_OUT:
387 /* Given a struct symbol for a variable,
388 and a stack frame id, read the value of the variable
389 and return a (pointer to a) struct value containing the value.
390 If the variable cannot be found, return a zero pointer.
391 If FRAME is NULL, use the deprecated_selected_frame. */
394 read_var_value (register struct symbol *var, struct frame_info *frame)
396 register struct value *v;
397 struct type *type = SYMBOL_TYPE (var);
401 v = allocate_value (type);
402 VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */
403 VALUE_BFD_SECTION (v) = SYMBOL_BFD_SECTION (var);
405 len = TYPE_LENGTH (type);
408 frame = deprecated_selected_frame;
410 switch (SYMBOL_CLASS (var))
413 /* Put the constant back in target format. */
414 store_signed_integer (VALUE_CONTENTS_RAW (v), len,
415 (LONGEST) SYMBOL_VALUE (var));
416 VALUE_LVAL (v) = not_lval;
420 /* Put the constant back in target format. */
421 if (overlay_debugging)
424 = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var),
425 SYMBOL_BFD_SECTION (var));
426 store_typed_address (VALUE_CONTENTS_RAW (v), type, addr);
429 store_typed_address (VALUE_CONTENTS_RAW (v), type,
430 SYMBOL_VALUE_ADDRESS (var));
431 VALUE_LVAL (v) = not_lval;
434 case LOC_CONST_BYTES:
437 bytes_addr = SYMBOL_VALUE_BYTES (var);
438 memcpy (VALUE_CONTENTS_RAW (v), bytes_addr, len);
439 VALUE_LVAL (v) = not_lval;
444 if (overlay_debugging)
445 addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var),
446 SYMBOL_BFD_SECTION (var));
448 addr = SYMBOL_VALUE_ADDRESS (var);
453 /* The import slot does not have a real address in it from the
454 dynamic loader (dld.sl on HP-UX), if the target hasn't
455 begun execution yet, so check for that. */
458 if (!target_has_execution)
460 Attempt to access variable defined in different shared object or load module when\n\
461 addresses have not been bound by the dynamic loader. Try again when executable is running.");
463 locaddr = SYMBOL_VALUE_ADDRESS (var);
464 loc = value_at (lookup_pointer_type (type), locaddr, NULL);
465 addr = value_as_address (loc);
471 addr = get_frame_args_address (frame);
474 addr += SYMBOL_VALUE (var);
483 argref = get_frame_args_address (frame);
486 argref += SYMBOL_VALUE (var);
487 ref = value_at (lookup_pointer_type (type), argref, NULL);
488 addr = value_as_address (ref);
496 addr = get_frame_locals_address (frame);
497 addr += SYMBOL_VALUE (var);
501 case LOC_BASEREG_ARG:
502 case LOC_HP_THREAD_LOCAL_STATIC:
504 struct value *regval;
506 regval = value_from_register (lookup_pointer_type (type),
507 SYMBOL_BASEREG (var), frame);
509 error ("Value of base register not available.");
510 addr = value_as_address (regval);
511 addr += SYMBOL_VALUE (var);
515 case LOC_THREAD_LOCAL_STATIC:
517 if (target_get_thread_local_address_p ())
518 addr = target_get_thread_local_address (inferior_ptid,
519 SYMBOL_OBJFILE (var),
520 SYMBOL_VALUE_ADDRESS (var));
521 /* It wouldn't be wrong here to try a gdbarch method, too;
522 finding TLS is an ABI-specific thing. But we don't do that
525 error ("Cannot find thread-local variables on this target");
530 error ("Cannot look up value of a typedef");
534 if (overlay_debugging)
535 VALUE_ADDRESS (v) = symbol_overlayed_address
536 (BLOCK_START (SYMBOL_BLOCK_VALUE (var)), SYMBOL_BFD_SECTION (var));
538 VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var));
543 case LOC_REGPARM_ADDR:
546 int regno = SYMBOL_VALUE (var);
547 struct value *regval;
551 b = get_frame_block (frame, 0);
553 if (SYMBOL_CLASS (var) == LOC_REGPARM_ADDR)
555 regval = value_from_register (lookup_pointer_type (type),
560 error ("Value of register variable not available.");
562 addr = value_as_address (regval);
563 VALUE_LVAL (v) = lval_memory;
567 regval = value_from_register (type, regno, frame);
570 error ("Value of register variable not available.");
577 case LOC_COMPUTED_ARG:
579 struct location_funcs *funcs = SYMBOL_LOCATION_FUNCS (var);
581 if (frame == 0 && (funcs->read_needs_frame) (var))
583 return (funcs->read_variable) (var, frame);
590 struct minimal_symbol *msym;
592 msym = lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var), NULL, NULL);
595 if (overlay_debugging)
596 addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym),
597 SYMBOL_BFD_SECTION (msym));
599 addr = SYMBOL_VALUE_ADDRESS (msym);
603 case LOC_OPTIMIZED_OUT:
604 VALUE_LVAL (v) = not_lval;
605 VALUE_OPTIMIZED_OUT (v) = 1;
609 error ("Cannot look up value of a botched symbol.");
613 VALUE_ADDRESS (v) = addr;
618 /* Return a value of type TYPE, stored in register REGNUM, in frame
621 NOTE: returns NULL if register value is not available.
622 Caller will check return value or die! */
625 value_from_register (struct type *type, int regnum, struct frame_info *frame)
627 struct gdbarch *gdbarch = get_frame_arch (frame);
628 struct value *v = allocate_value (type);
629 CHECK_TYPEDEF (type);
631 if (CONVERT_REGISTER_P (regnum, type))
633 /* The ISA/ABI need to something weird when obtaining the
634 specified value from this register. It might need to
635 re-order non-adjacent, starting with REGNUM (see MIPS and
636 i386). It might need to convert the [float] register into
637 the corresponding [integer] type (see Alpha). The assumption
638 is that REGISTER_TO_VALUE populates the entire value
639 including the location. */
640 REGISTER_TO_VALUE (frame, regnum, type, VALUE_CONTENTS_RAW (v));
641 VALUE_LVAL (v) = lval_reg_frame_relative;
642 VALUE_FRAME_ID (v) = get_frame_id (frame);
643 VALUE_FRAME_REGNUM (v) = regnum;
648 int mem_stor = 0, reg_stor = 0;
649 int mem_tracking = 1;
650 CORE_ADDR last_addr = 0;
651 CORE_ADDR first_addr = 0;
652 int first_realnum = regnum;
653 int len = TYPE_LENGTH (type);
654 int value_bytes_copied;
656 char *value_bytes = (char *) alloca (len + MAX_REGISTER_SIZE);
658 /* Copy all of the data out, whereever it may be. */
659 for (local_regnum = regnum, value_bytes_copied = 0;
660 value_bytes_copied < len;
661 (value_bytes_copied += REGISTER_RAW_SIZE (local_regnum),
668 frame_register (frame, local_regnum, &optim, &lval, &addr,
669 &realnum, value_bytes + value_bytes_copied);
671 if (register_cached (local_regnum) == -1)
672 return NULL; /* register value not available */
674 if (regnum == local_regnum)
677 first_realnum = realnum;
679 if (lval == lval_register)
685 mem_tracking = (mem_tracking
686 && (regnum == local_regnum
687 || addr == last_addr));
692 /* FIXME: cagney/2003-06-04: Shouldn't this always use
693 lval_reg_frame_relative? If it doesn't and the register's
694 location changes (say after a resume) then this value is
695 going to have wrong information. */
696 if ((reg_stor && mem_stor)
697 || (mem_stor && !mem_tracking))
698 /* Mixed storage; all of the hassle we just went through was
699 for some good purpose. */
701 VALUE_LVAL (v) = lval_reg_frame_relative;
702 VALUE_FRAME_ID (v) = get_frame_id (frame);
703 VALUE_FRAME_REGNUM (v) = regnum;
707 VALUE_LVAL (v) = lval_memory;
708 VALUE_ADDRESS (v) = first_addr;
712 VALUE_LVAL (v) = lval_register;
713 VALUE_ADDRESS (v) = first_addr;
714 VALUE_REGNO (v) = first_realnum;
717 internal_error (__FILE__, __LINE__,
718 "value_from_register: Value not stored anywhere!");
720 VALUE_OPTIMIZED_OUT (v) = optimized;
722 /* Any structure stored in more than one register will always be
723 an integral number of registers. Otherwise, you need to do
724 some fiddling with the last register copied here for little
726 if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
727 && len < REGISTER_RAW_SIZE (regnum))
728 /* Big-endian, and we want less than full size. */
729 VALUE_OFFSET (v) = REGISTER_RAW_SIZE (regnum) - len;
731 VALUE_OFFSET (v) = 0;
732 memcpy (VALUE_CONTENTS_RAW (v), value_bytes + VALUE_OFFSET (v), len);
738 /* Given a struct symbol for a variable or function,
739 and a stack frame id,
740 return a (pointer to a) struct value containing the properly typed
744 locate_var_value (register struct symbol *var, struct frame_info *frame)
747 struct type *type = SYMBOL_TYPE (var);
748 struct value *lazy_value;
750 /* Evaluate it first; if the result is a memory address, we're fine.
751 Lazy evaluation pays off here. */
753 lazy_value = read_var_value (var, frame);
755 error ("Address of \"%s\" is unknown.", SYMBOL_PRINT_NAME (var));
757 if (VALUE_LAZY (lazy_value)
758 || TYPE_CODE (type) == TYPE_CODE_FUNC)
762 addr = VALUE_ADDRESS (lazy_value);
763 val = value_from_pointer (lookup_pointer_type (type), addr);
764 VALUE_BFD_SECTION (val) = VALUE_BFD_SECTION (lazy_value);
768 /* Not a memory address; check what the problem was. */
769 switch (VALUE_LVAL (lazy_value))
772 gdb_assert (REGISTER_NAME (VALUE_REGNO (lazy_value)) != NULL
773 && *REGISTER_NAME (VALUE_REGNO (lazy_value)) != '\0');
774 error("Address requested for identifier "
775 "\"%s\" which is in register $%s",
776 SYMBOL_PRINT_NAME (var),
777 REGISTER_NAME (VALUE_REGNO (lazy_value)));
780 case lval_reg_frame_relative:
781 gdb_assert (REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value)) != NULL
782 && *REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value)) != '\0');
783 error("Address requested for identifier "
784 "\"%s\" which is in frame register $%s",
785 SYMBOL_PRINT_NAME (var),
786 REGISTER_NAME (VALUE_FRAME_REGNUM (lazy_value)));
790 error ("Can't take address of \"%s\" which isn't an lvalue.",
791 SYMBOL_PRINT_NAME (var));
794 return 0; /* For lint -- never reached */