| /* Find a variable's value in memory, for GDB, the GNU debugger. |
| |
| Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, |
| 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2007, 2008 |
| Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "defs.h" |
| #include "symtab.h" |
| #include "gdbtypes.h" |
| #include "frame.h" |
| #include "value.h" |
| #include "gdbcore.h" |
| #include "inferior.h" |
| #include "target.h" |
| #include "gdb_string.h" |
| #include "gdb_assert.h" |
| #include "floatformat.h" |
| #include "symfile.h" /* for overlay functions */ |
| #include "regcache.h" |
| #include "user-regs.h" |
| #include "block.h" |
| |
| /* Basic byte-swapping routines. GDB has needed these for a long time... |
| All extract a target-format integer at ADDR which is LEN bytes long. */ |
| |
| #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8 |
| /* 8 bit characters are a pretty safe assumption these days, so we |
| assume it throughout all these swapping routines. If we had to deal with |
| 9 bit characters, we would need to make len be in bits and would have |
| to re-write these routines... */ |
| you lose |
| #endif |
| |
| LONGEST |
| extract_signed_integer (const gdb_byte *addr, int len) |
| { |
| LONGEST retval; |
| const unsigned char *p; |
| const unsigned char *startaddr = addr; |
| const unsigned char *endaddr = startaddr + len; |
| |
| if (len > (int) sizeof (LONGEST)) |
| error (_("\ |
| That operation is not available on integers of more than %d bytes."), |
| (int) sizeof (LONGEST)); |
| |
| /* Start at the most significant end of the integer, and work towards |
| the least significant. */ |
| if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) |
| { |
| p = startaddr; |
| /* Do the sign extension once at the start. */ |
| retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| for (++p; p < endaddr; ++p) |
| retval = (retval << 8) | *p; |
| } |
| else |
| { |
| p = endaddr - 1; |
| /* Do the sign extension once at the start. */ |
| retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| for (--p; p >= startaddr; --p) |
| retval = (retval << 8) | *p; |
| } |
| return retval; |
| } |
| |
| ULONGEST |
| extract_unsigned_integer (const gdb_byte *addr, int len) |
| { |
| ULONGEST retval; |
| const unsigned char *p; |
| const unsigned char *startaddr = addr; |
| const unsigned char *endaddr = startaddr + len; |
| |
| if (len > (int) sizeof (ULONGEST)) |
| error (_("\ |
| That operation is not available on integers of more than %d bytes."), |
| (int) sizeof (ULONGEST)); |
| |
| /* Start at the most significant end of the integer, and work towards |
| the least significant. */ |
| retval = 0; |
| if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) |
| { |
| for (p = startaddr; p < endaddr; ++p) |
| retval = (retval << 8) | *p; |
| } |
| else |
| { |
| for (p = endaddr - 1; p >= startaddr; --p) |
| retval = (retval << 8) | *p; |
| } |
| return retval; |
| } |
| |
| /* Sometimes a long long unsigned integer can be extracted as a |
| LONGEST value. This is done so that we can print these values |
| better. If this integer can be converted to a LONGEST, this |
| function returns 1 and sets *PVAL. Otherwise it returns 0. */ |
| |
| int |
| extract_long_unsigned_integer (const gdb_byte *addr, int orig_len, |
| LONGEST *pval) |
| { |
| const gdb_byte *p; |
| const gdb_byte *first_addr; |
| int len; |
| |
| len = orig_len; |
| if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) |
| { |
| for (p = addr; |
| len > (int) sizeof (LONGEST) && p < addr + orig_len; |
| p++) |
| { |
| if (*p == 0) |
| len--; |
| else |
| break; |
| } |
| first_addr = p; |
| } |
| else |
| { |
| first_addr = addr; |
| for (p = addr + orig_len - 1; |
| len > (int) sizeof (LONGEST) && p >= addr; |
| p--) |
| { |
| if (*p == 0) |
| len--; |
| else |
| break; |
| } |
| } |
| |
| if (len <= (int) sizeof (LONGEST)) |
| { |
| *pval = (LONGEST) extract_unsigned_integer (first_addr, |
| sizeof (LONGEST)); |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| |
| /* Treat the bytes at BUF as a pointer of type TYPE, and return the |
| address it represents. */ |
| CORE_ADDR |
| extract_typed_address (const gdb_byte *buf, struct type *type) |
| { |
| if (TYPE_CODE (type) != TYPE_CODE_PTR |
| && TYPE_CODE (type) != TYPE_CODE_REF) |
| internal_error (__FILE__, __LINE__, |
| _("extract_typed_address: " |
| "type is not a pointer or reference")); |
| |
| return gdbarch_pointer_to_address (current_gdbarch, type, buf); |
| } |
| |
| |
| void |
| store_signed_integer (gdb_byte *addr, int len, LONGEST val) |
| { |
| gdb_byte *p; |
| gdb_byte *startaddr = addr; |
| gdb_byte *endaddr = startaddr + len; |
| |
| /* Start at the least significant end of the integer, and work towards |
| the most significant. */ |
| if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) |
| { |
| for (p = endaddr - 1; p >= startaddr; --p) |
| { |
| *p = val & 0xff; |
| val >>= 8; |
| } |
| } |
| else |
| { |
| for (p = startaddr; p < endaddr; ++p) |
| { |
| *p = val & 0xff; |
| val >>= 8; |
| } |
| } |
| } |
| |
| void |
| store_unsigned_integer (gdb_byte *addr, int len, ULONGEST val) |
| { |
| unsigned char *p; |
| unsigned char *startaddr = (unsigned char *) addr; |
| unsigned char *endaddr = startaddr + len; |
| |
| /* Start at the least significant end of the integer, and work towards |
| the most significant. */ |
| if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) |
| { |
| for (p = endaddr - 1; p >= startaddr; --p) |
| { |
| *p = val & 0xff; |
| val >>= 8; |
| } |
| } |
| else |
| { |
| for (p = startaddr; p < endaddr; ++p) |
| { |
| *p = val & 0xff; |
| val >>= 8; |
| } |
| } |
| } |
| |
| /* Store the address ADDR as a pointer of type TYPE at BUF, in target |
| form. */ |
| void |
| store_typed_address (gdb_byte *buf, struct type *type, CORE_ADDR addr) |
| { |
| if (TYPE_CODE (type) != TYPE_CODE_PTR |
| && TYPE_CODE (type) != TYPE_CODE_REF) |
| internal_error (__FILE__, __LINE__, |
| _("store_typed_address: " |
| "type is not a pointer or reference")); |
| |
| gdbarch_address_to_pointer (current_gdbarch, type, buf, addr); |
| } |
| |
| |
| |
| /* Return a `value' with the contents of (virtual or cooked) register |
| REGNUM as found in the specified FRAME. The register's type is |
| determined by register_type(). */ |
| |
| struct value * |
| value_of_register (int regnum, struct frame_info *frame) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (frame); |
| CORE_ADDR addr; |
| int optim; |
| struct value *reg_val; |
| int realnum; |
| gdb_byte raw_buffer[MAX_REGISTER_SIZE]; |
| enum lval_type lval; |
| |
| /* User registers lie completely outside of the range of normal |
| registers. Catch them early so that the target never sees them. */ |
| if (regnum >= gdbarch_num_regs (gdbarch) |
| + gdbarch_num_pseudo_regs (gdbarch)) |
| return value_of_user_reg (regnum, frame); |
| |
| frame_register (frame, regnum, &optim, &lval, &addr, &realnum, raw_buffer); |
| |
| reg_val = allocate_value (register_type (gdbarch, regnum)); |
| |
| memcpy (value_contents_raw (reg_val), raw_buffer, |
| register_size (gdbarch, regnum)); |
| VALUE_LVAL (reg_val) = lval; |
| VALUE_ADDRESS (reg_val) = addr; |
| VALUE_REGNUM (reg_val) = regnum; |
| set_value_optimized_out (reg_val, optim); |
| VALUE_FRAME_ID (reg_val) = get_frame_id (frame); |
| return reg_val; |
| } |
| |
| /* Given a pointer of type TYPE in target form in BUF, return the |
| address it represents. */ |
| CORE_ADDR |
| unsigned_pointer_to_address (struct type *type, const gdb_byte *buf) |
| { |
| return extract_unsigned_integer (buf, TYPE_LENGTH (type)); |
| } |
| |
| CORE_ADDR |
| signed_pointer_to_address (struct type *type, const gdb_byte *buf) |
| { |
| return extract_signed_integer (buf, TYPE_LENGTH (type)); |
| } |
| |
| /* Given an address, store it as a pointer of type TYPE in target |
| format in BUF. */ |
| void |
| unsigned_address_to_pointer (struct type *type, gdb_byte *buf, |
| CORE_ADDR addr) |
| { |
| store_unsigned_integer (buf, TYPE_LENGTH (type), addr); |
| } |
| |
| void |
| address_to_signed_pointer (struct type *type, gdb_byte *buf, CORE_ADDR addr) |
| { |
| store_signed_integer (buf, TYPE_LENGTH (type), addr); |
| } |
| |
| /* Will calling read_var_value or locate_var_value on SYM end |
| up caring what frame it is being evaluated relative to? SYM must |
| be non-NULL. */ |
| int |
| symbol_read_needs_frame (struct symbol *sym) |
| { |
| switch (SYMBOL_CLASS (sym)) |
| { |
| /* All cases listed explicitly so that gcc -Wall will detect it if |
| we failed to consider one. */ |
| case LOC_COMPUTED: |
| case LOC_COMPUTED_ARG: |
| /* FIXME: cagney/2004-01-26: It should be possible to |
| unconditionally call the SYMBOL_OPS method when available. |
| Unfortunately DWARF 2 stores the frame-base (instead of the |
| function) location in a function's symbol. Oops! For the |
| moment enable this when/where applicable. */ |
| return SYMBOL_OPS (sym)->read_needs_frame (sym); |
| |
| case LOC_REGISTER: |
| case LOC_ARG: |
| case LOC_REF_ARG: |
| case LOC_REGPARM: |
| case LOC_REGPARM_ADDR: |
| case LOC_LOCAL: |
| case LOC_LOCAL_ARG: |
| case LOC_BASEREG: |
| case LOC_BASEREG_ARG: |
| case LOC_HP_THREAD_LOCAL_STATIC: |
| return 1; |
| |
| case LOC_UNDEF: |
| case LOC_CONST: |
| case LOC_STATIC: |
| case LOC_INDIRECT: |
| case LOC_TYPEDEF: |
| |
| case LOC_LABEL: |
| /* Getting the address of a label can be done independently of the block, |
| even if some *uses* of that address wouldn't work so well without |
| the right frame. */ |
| |
| case LOC_BLOCK: |
| case LOC_CONST_BYTES: |
| case LOC_UNRESOLVED: |
| case LOC_OPTIMIZED_OUT: |
| return 0; |
| } |
| return 1; |
| } |
| |
| /* Given a struct symbol for a variable, |
| and a stack frame id, read the value of the variable |
| and return a (pointer to a) struct value containing the value. |
| If the variable cannot be found, return a zero pointer. |
| If FRAME is NULL, use the selected frame. */ |
| |
| struct value * |
| read_var_value (struct symbol *var, struct frame_info *frame) |
| { |
| struct value *v; |
| struct type *type = SYMBOL_TYPE (var); |
| CORE_ADDR addr; |
| int len; |
| |
| if (SYMBOL_CLASS (var) == LOC_COMPUTED |
| || SYMBOL_CLASS (var) == LOC_COMPUTED_ARG |
| || SYMBOL_CLASS (var) == LOC_REGISTER |
| || SYMBOL_CLASS (var) == LOC_REGPARM) |
| /* These cases do not use V. */ |
| v = NULL; |
| else |
| { |
| v = allocate_value (type); |
| VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */ |
| } |
| |
| len = TYPE_LENGTH (type); |
| |
| /* FIXME drow/2003-09-06: this call to the selected frame should be |
| pushed upwards to the callers. */ |
| if (frame == NULL) |
| frame = deprecated_safe_get_selected_frame (); |
| |
| switch (SYMBOL_CLASS (var)) |
| { |
| case LOC_CONST: |
| /* Put the constant back in target format. */ |
| store_signed_integer (value_contents_raw (v), len, |
| (LONGEST) SYMBOL_VALUE (var)); |
| VALUE_LVAL (v) = not_lval; |
| return v; |
| |
| case LOC_LABEL: |
| /* Put the constant back in target format. */ |
| if (overlay_debugging) |
| { |
| CORE_ADDR addr |
| = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| SYMBOL_BFD_SECTION (var)); |
| store_typed_address (value_contents_raw (v), type, addr); |
| } |
| else |
| store_typed_address (value_contents_raw (v), type, |
| SYMBOL_VALUE_ADDRESS (var)); |
| VALUE_LVAL (v) = not_lval; |
| return v; |
| |
| case LOC_CONST_BYTES: |
| { |
| memcpy (value_contents_raw (v), SYMBOL_VALUE_BYTES (var), len); |
| VALUE_LVAL (v) = not_lval; |
| return v; |
| } |
| |
| case LOC_STATIC: |
| if (overlay_debugging) |
| addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| SYMBOL_BFD_SECTION (var)); |
| else |
| addr = SYMBOL_VALUE_ADDRESS (var); |
| break; |
| |
| case LOC_INDIRECT: |
| { |
| /* The import slot does not have a real address in it from the |
| dynamic loader (dld.sl on HP-UX), if the target hasn't |
| begun execution yet, so check for that. */ |
| CORE_ADDR locaddr; |
| struct value *loc; |
| if (!target_has_execution) |
| error (_("\ |
| Attempt to access variable defined in different shared object or load module when\n\ |
| addresses have not been bound by the dynamic loader. Try again when executable is running.")); |
| |
| locaddr = SYMBOL_VALUE_ADDRESS (var); |
| loc = value_at (lookup_pointer_type (type), locaddr); |
| addr = value_as_address (loc); |
| break; |
| } |
| |
| case LOC_ARG: |
| if (frame == NULL) |
| return 0; |
| addr = get_frame_args_address (frame); |
| if (!addr) |
| return 0; |
| addr += SYMBOL_VALUE (var); |
| break; |
| |
| case LOC_REF_ARG: |
| { |
| struct value *ref; |
| CORE_ADDR argref; |
| if (frame == NULL) |
| return 0; |
| argref = get_frame_args_address (frame); |
| if (!argref) |
| return 0; |
| argref += SYMBOL_VALUE (var); |
| ref = value_at (lookup_pointer_type (type), argref); |
| addr = value_as_address (ref); |
| break; |
| } |
| |
| case LOC_LOCAL: |
| case LOC_LOCAL_ARG: |
| if (frame == NULL) |
| return 0; |
| addr = get_frame_locals_address (frame); |
| addr += SYMBOL_VALUE (var); |
| break; |
| |
| case LOC_BASEREG: |
| case LOC_BASEREG_ARG: |
| case LOC_HP_THREAD_LOCAL_STATIC: |
| { |
| struct value *regval; |
| |
| regval = value_from_register (lookup_pointer_type (type), |
| SYMBOL_BASEREG (var), frame); |
| if (regval == NULL) |
| error (_("Value of base register not available.")); |
| addr = value_as_address (regval); |
| addr += SYMBOL_VALUE (var); |
| break; |
| } |
| |
| case LOC_TYPEDEF: |
| error (_("Cannot look up value of a typedef")); |
| break; |
| |
| case LOC_BLOCK: |
| if (overlay_debugging) |
| VALUE_ADDRESS (v) = symbol_overlayed_address |
| (BLOCK_START (SYMBOL_BLOCK_VALUE (var)), SYMBOL_BFD_SECTION (var)); |
| else |
| VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); |
| return v; |
| |
| case LOC_REGISTER: |
| case LOC_REGPARM: |
| case LOC_REGPARM_ADDR: |
| { |
| struct block *b; |
| int regno = SYMBOL_VALUE (var); |
| struct value *regval; |
| |
| if (frame == NULL) |
| return 0; |
| b = get_frame_block (frame, 0); |
| |
| if (SYMBOL_CLASS (var) == LOC_REGPARM_ADDR) |
| { |
| regval = value_from_register (lookup_pointer_type (type), |
| regno, |
| frame); |
| |
| if (regval == NULL) |
| error (_("Value of register variable not available.")); |
| |
| addr = value_as_address (regval); |
| VALUE_LVAL (v) = lval_memory; |
| } |
| else |
| { |
| regval = value_from_register (type, regno, frame); |
| |
| if (regval == NULL) |
| error (_("Value of register variable not available.")); |
| return regval; |
| } |
| } |
| break; |
| |
| case LOC_COMPUTED: |
| case LOC_COMPUTED_ARG: |
| /* FIXME: cagney/2004-01-26: It should be possible to |
| unconditionally call the SYMBOL_OPS method when available. |
| Unfortunately DWARF 2 stores the frame-base (instead of the |
| function) location in a function's symbol. Oops! For the |
| moment enable this when/where applicable. */ |
| if (frame == 0 && SYMBOL_OPS (var)->read_needs_frame (var)) |
| return 0; |
| return SYMBOL_OPS (var)->read_variable (var, frame); |
| |
| case LOC_UNRESOLVED: |
| { |
| struct minimal_symbol *msym; |
| |
| msym = lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var), NULL, NULL); |
| if (msym == NULL) |
| return 0; |
| if (overlay_debugging) |
| addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym), |
| SYMBOL_BFD_SECTION (msym)); |
| else |
| addr = SYMBOL_VALUE_ADDRESS (msym); |
| } |
| break; |
| |
| case LOC_OPTIMIZED_OUT: |
| VALUE_LVAL (v) = not_lval; |
| set_value_optimized_out (v, 1); |
| return v; |
| |
| default: |
| error (_("Cannot look up value of a botched symbol.")); |
| break; |
| } |
| |
| VALUE_ADDRESS (v) = addr; |
| set_value_lazy (v, 1); |
| return v; |
| } |
| |
| /* Install default attributes for register values. */ |
| |
| struct value * |
| default_value_from_register (struct type *type, int regnum, |
| struct frame_info *frame) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (frame); |
| int len = TYPE_LENGTH (type); |
| struct value *value = allocate_value (type); |
| |
| VALUE_LVAL (value) = lval_register; |
| VALUE_FRAME_ID (value) = get_frame_id (frame); |
| VALUE_REGNUM (value) = regnum; |
| |
| /* Any structure stored in more than one register will always be |
| an integral number of registers. Otherwise, you need to do |
| some fiddling with the last register copied here for little |
| endian machines. */ |
| if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG |
| && len < register_size (gdbarch, regnum)) |
| /* Big-endian, and we want less than full size. */ |
| set_value_offset (value, register_size (gdbarch, regnum) - len); |
| else |
| set_value_offset (value, 0); |
| |
| return value; |
| } |
| |
| /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */ |
| |
| struct value * |
| value_from_register (struct type *type, int regnum, struct frame_info *frame) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (frame); |
| struct type *type1 = check_typedef (type); |
| struct value *v; |
| |
| if (gdbarch_convert_register_p (gdbarch, regnum, type1)) |
| { |
| /* The ISA/ABI need to something weird when obtaining the |
| specified value from this register. It might need to |
| re-order non-adjacent, starting with REGNUM (see MIPS and |
| i386). It might need to convert the [float] register into |
| the corresponding [integer] type (see Alpha). The assumption |
| is that gdbarch_register_to_value populates the entire value |
| including the location. */ |
| v = allocate_value (type); |
| VALUE_LVAL (v) = lval_register; |
| VALUE_FRAME_ID (v) = get_frame_id (frame); |
| VALUE_REGNUM (v) = regnum; |
| gdbarch_register_to_value (gdbarch, |
| frame, regnum, type1, value_contents_raw (v)); |
| } |
| else |
| { |
| int len = TYPE_LENGTH (type); |
| |
| /* Construct the value. */ |
| v = gdbarch_value_from_register (gdbarch, type, regnum, frame); |
| |
| /* Get the data. */ |
| if (!get_frame_register_bytes (frame, regnum, value_offset (v), len, |
| value_contents_raw (v))) |
| set_value_optimized_out (v, 1); |
| } |
| return v; |
| } |
| |
| /* Return contents of register REGNUM in frame FRAME as address, |
| interpreted as value of type TYPE. Will abort if register |
| value is not available. */ |
| |
| CORE_ADDR |
| address_from_register (struct type *type, int regnum, struct frame_info *frame) |
| { |
| struct value *value; |
| CORE_ADDR result; |
| |
| value = value_from_register (type, regnum, frame); |
| gdb_assert (value); |
| |
| result = value_as_address (value); |
| release_value (value); |
| value_free (value); |
| |
| return result; |
| } |
| |
| |
| /* Given a struct symbol for a variable or function, |
| and a stack frame id, |
| return a (pointer to a) struct value containing the properly typed |
| address. */ |
| |
| struct value * |
| locate_var_value (struct symbol *var, struct frame_info *frame) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (frame); |
| CORE_ADDR addr = 0; |
| struct type *type = SYMBOL_TYPE (var); |
| struct value *lazy_value; |
| |
| /* Evaluate it first; if the result is a memory address, we're fine. |
| Lazy evaluation pays off here. */ |
| |
| lazy_value = read_var_value (var, frame); |
| if (lazy_value == 0) |
| error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var)); |
| |
| if (value_lazy (lazy_value) |
| || TYPE_CODE (type) == TYPE_CODE_FUNC) |
| { |
| struct value *val; |
| |
| addr = VALUE_ADDRESS (lazy_value); |
| val = value_from_pointer (lookup_pointer_type (type), addr); |
| return val; |
| } |
| |
| /* Not a memory address; check what the problem was. */ |
| switch (VALUE_LVAL (lazy_value)) |
| { |
| case lval_register: |
| gdb_assert (gdbarch_register_name |
| (gdbarch, VALUE_REGNUM (lazy_value)) != NULL |
| && *gdbarch_register_name |
| (gdbarch, VALUE_REGNUM (lazy_value)) != '\0'); |
| error (_("Address requested for identifier " |
| "\"%s\" which is in register $%s"), |
| SYMBOL_PRINT_NAME (var), |
| gdbarch_register_name (gdbarch, VALUE_REGNUM (lazy_value))); |
| break; |
| |
| default: |
| error (_("Can't take address of \"%s\" which isn't an lvalue."), |
| SYMBOL_PRINT_NAME (var)); |
| break; |
| } |
| return 0; /* For lint -- never reached */ |
| } |