/* Find a variable's value in memory, for GDB, the GNU debugger. Copyright 1986, 1987, 1989, 1991 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 2 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, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include "defs.h" #include "symtab.h" #include "gdbtypes.h" #include "frame.h" #include "value.h" #include "gdbcore.h" #include "inferior.h" #include "target.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 (addr, len) PTR addr; int len; { LONGEST retval; unsigned char *p; unsigned char *startaddr = (unsigned char *)addr; unsigned char *endaddr = startaddr + len; if (len > sizeof (LONGEST)) error ("\ That operation is not available on integers of more than %d bytes.", sizeof (LONGEST)); /* Start at the most significant end of the integer, and work towards the least significant. */ #if TARGET_BYTE_ORDER == BIG_ENDIAN p = startaddr; #else p = endaddr - 1; #endif /* Do the sign extension once at the start. */ retval = (*p ^ 0x80) - 0x80; #if TARGET_BYTE_ORDER == BIG_ENDIAN for (++p; p < endaddr; ++p) #else for (--p; p >= startaddr; --p) #endif { retval = (retval << 8) | *p; } return retval; } unsigned LONGEST extract_unsigned_integer (addr, len) PTR addr; int len; { unsigned LONGEST retval; unsigned char *p; unsigned char *startaddr = (unsigned char *)addr; unsigned char *endaddr = startaddr + len; if (len > sizeof (unsigned LONGEST)) error ("\ That operation is not available on integers of more than %d bytes.", sizeof (unsigned LONGEST)); /* Start at the most significant end of the integer, and work towards the least significant. */ retval = 0; #if TARGET_BYTE_ORDER == BIG_ENDIAN for (p = startaddr; p < endaddr; ++p) #else for (p = endaddr - 1; p >= startaddr; --p) #endif { retval = (retval << 8) | *p; } return retval; } CORE_ADDR extract_address (addr, len) PTR addr; int len; { /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure whether we want this to be true eventually. */ return extract_unsigned_integer (addr, len); } void store_signed_integer (addr, len, val) PTR addr; int len; LONGEST 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 TARGET_BYTE_ORDER == BIG_ENDIAN for (p = endaddr - 1; p >= startaddr; --p) #else for (p = startaddr; p < endaddr; ++p) #endif { *p = val & 0xff; val >>= 8; } } void store_unsigned_integer (addr, len, val) PTR addr; int len; unsigned LONGEST 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 TARGET_BYTE_ORDER == BIG_ENDIAN for (p = endaddr - 1; p >= startaddr; --p) #else for (p = startaddr; p < endaddr; ++p) #endif { *p = val & 0xff; val >>= 8; } } void store_address (addr, len, val) PTR addr; int len; CORE_ADDR val; { /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure whether we want this to be true eventually. */ store_unsigned_integer (addr, len, (LONGEST)val); } #if !defined (GET_SAVED_REGISTER) /* Return the address in which frame FRAME's value of register REGNUM has been saved in memory. Or return zero if it has not been saved. If REGNUM specifies the SP, the value we return is actually the SP value, not an address where it was saved. */ CORE_ADDR find_saved_register (frame, regnum) FRAME frame; int regnum; { struct frame_info *fi; struct frame_saved_regs saved_regs; register FRAME frame1 = 0; register CORE_ADDR addr = 0; if (frame == 0) /* No regs saved if want current frame */ return 0; #ifdef HAVE_REGISTER_WINDOWS /* We assume that a register in a register window will only be saved in one place (since the name changes and/or disappears as you go towards inner frames), so we only call get_frame_saved_regs on the current frame. This is directly in contradiction to the usage below, which assumes that registers used in a frame must be saved in a lower (more interior) frame. This change is a result of working on a register window machine; get_frame_saved_regs always returns the registers saved within a frame, within the context (register namespace) of that frame. */ /* However, note that we don't want this to return anything if nothing is saved (if there's a frame inside of this one). Also, callers to this routine asking for the stack pointer want the stack pointer saved for *this* frame; this is returned from the next frame. */ if (REGISTER_IN_WINDOW_P(regnum)) { frame1 = get_next_frame (frame); if (!frame1) return 0; /* Registers of this frame are active. */ /* Get the SP from the next frame in; it will be this current frame. */ if (regnum != SP_REGNUM) frame1 = frame; fi = get_frame_info (frame1); get_frame_saved_regs (fi, &saved_regs); return saved_regs.regs[regnum]; /* ... which might be zero */ } #endif /* HAVE_REGISTER_WINDOWS */ /* Note that this next routine assumes that registers used in frame x will be saved only in the frame that x calls and frames interior to it. This is not true on the sparc, but the above macro takes care of it, so we should be all right. */ while (1) { QUIT; frame1 = get_prev_frame (frame1); if (frame1 == 0 || frame1 == frame) break; fi = get_frame_info (frame1); get_frame_saved_regs (fi, &saved_regs); if (saved_regs.regs[regnum]) addr = saved_regs.regs[regnum]; } return addr; } /* Find register number REGNUM relative to FRAME and put its (raw, target format) contents in *RAW_BUFFER. Set *OPTIMIZED if the variable was optimized out (and thus can't be fetched). Set *LVAL to lval_memory, lval_register, or not_lval, depending on whether the value was fetched from memory, from a register, or in a strange and non-modifiable way (e.g. a frame pointer which was calculated rather than fetched). Set *ADDRP to the address, either in memory on as a REGISTER_BYTE offset into the registers array. Note that this implementation never sets *LVAL to not_lval. But it can be replaced by defining GET_SAVED_REGISTER and supplying your own. The argument RAW_BUFFER must point to aligned memory. */ void get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval) char *raw_buffer; int *optimized; CORE_ADDR *addrp; FRAME frame; int regnum; enum lval_type *lval; { CORE_ADDR addr; /* Normal systems don't optimize out things with register numbers. */ if (optimized != NULL) *optimized = 0; addr = find_saved_register (frame, regnum); if (addr != 0) { if (lval != NULL) *lval = lval_memory; if (regnum == SP_REGNUM) { if (raw_buffer != NULL) { /* Put it back in target format. */ store_address (raw_buffer, REGISTER_RAW_SIZE (regnum), addr); } if (addrp != NULL) *addrp = 0; return; } if (raw_buffer != NULL) read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (regnum)); } else { if (lval != NULL) *lval = lval_register; addr = REGISTER_BYTE (regnum); if (raw_buffer != NULL) read_register_gen (regnum, raw_buffer); } if (addrp != NULL) *addrp = addr; } #endif /* GET_SAVED_REGISTER. */ /* Copy the bytes of register REGNUM, relative to the current stack frame, into our memory at MYADDR, in target byte order. The number of bytes copied is REGISTER_RAW_SIZE (REGNUM). Returns 1 if could not be read, 0 if could. */ int read_relative_register_raw_bytes (regnum, myaddr) int regnum; char *myaddr; { int optim; if (regnum == FP_REGNUM && selected_frame) { /* Put it back in target format. */ store_address (myaddr, REGISTER_RAW_SIZE(FP_REGNUM), FRAME_FP(selected_frame)); return 0; } get_saved_register (myaddr, &optim, (CORE_ADDR *) NULL, selected_frame, regnum, (enum lval_type *)NULL); return optim; } /* Return a `value' with the contents of register REGNUM in its virtual format, with the type specified by REGISTER_VIRTUAL_TYPE. */ value value_of_register (regnum) int regnum; { CORE_ADDR addr; int optim; register value val; char raw_buffer[MAX_REGISTER_RAW_SIZE]; char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE]; enum lval_type lval; get_saved_register (raw_buffer, &optim, &addr, selected_frame, regnum, &lval); REGISTER_CONVERT_TO_VIRTUAL (regnum, raw_buffer, virtual_buffer); val = allocate_value (REGISTER_VIRTUAL_TYPE (regnum)); memcpy (VALUE_CONTENTS_RAW (val), virtual_buffer, REGISTER_VIRTUAL_SIZE (regnum)); VALUE_LVAL (val) = lval; VALUE_ADDRESS (val) = addr; VALUE_REGNO (val) = regnum; VALUE_OPTIMIZED_OUT (val) = optim; return val; } /* Low level examining and depositing of registers. The caller is responsible for making sure that the inferior is stopped before calling the fetching routines, or it will get garbage. (a change from GDB version 3, in which the caller got the value from the last stop). */ /* Contents of the registers in target byte order. We allocate some extra slop since we do a lot of memcpy's around `registers', and failing-soft is better than failing hard. */ char registers[REGISTER_BYTES + /* SLOP */ 256]; /* Nonzero if that register has been fetched. */ char register_valid[NUM_REGS]; /* Indicate that registers may have changed, so invalidate the cache. */ void registers_changed () { int i; for (i = 0; i < NUM_REGS; i++) register_valid[i] = 0; } /* Indicate that all registers have been fetched, so mark them all valid. */ void registers_fetched () { int i; for (i = 0; i < NUM_REGS; i++) register_valid[i] = 1; } /* Copy LEN bytes of consecutive data from registers starting with the REGBYTE'th byte of register data into memory at MYADDR. */ void read_register_bytes (regbyte, myaddr, len) int regbyte; char *myaddr; int len; { /* Fetch all registers. */ int i; for (i = 0; i < NUM_REGS; i++) if (!register_valid[i]) { target_fetch_registers (-1); break; } if (myaddr != NULL) memcpy (myaddr, ®isters[regbyte], len); } /* Read register REGNO into memory at MYADDR, which must be large enough for REGISTER_RAW_BYTES (REGNO). Target byte-order. If the register is known to be the size of a CORE_ADDR or smaller, read_register can be used instead. */ void read_register_gen (regno, myaddr) int regno; char *myaddr; { if (!register_valid[regno]) target_fetch_registers (regno); memcpy (myaddr, ®isters[REGISTER_BYTE (regno)], REGISTER_RAW_SIZE (regno)); } /* Copy LEN bytes of consecutive data from memory at MYADDR into registers starting with the REGBYTE'th byte of register data. */ void write_register_bytes (regbyte, myaddr, len) int regbyte; char *myaddr; int len; { /* Make sure the entire registers array is valid. */ read_register_bytes (0, (char *)NULL, REGISTER_BYTES); memcpy (®isters[regbyte], myaddr, len); target_store_registers (-1); } /* Return the raw contents of register REGNO, regarding it as an integer. */ /* This probably should be returning LONGEST rather than CORE_ADDR. */ CORE_ADDR read_register (regno) int regno; { if (!register_valid[regno]) target_fetch_registers (regno); return extract_address (®isters[REGISTER_BYTE (regno)], REGISTER_RAW_SIZE(regno)); } /* Registers we shouldn't try to store. */ #if !defined (CANNOT_STORE_REGISTER) #define CANNOT_STORE_REGISTER(regno) 0 #endif /* Store VALUE, into the raw contents of register number REGNO. */ /* FIXME: The val arg should probably be a LONGEST. */ void write_register (regno, val) int regno, val; { PTR buf; int size; /* On the sparc, writing %g0 is a no-op, so we don't even want to change the registers array if something writes to this register. */ if (CANNOT_STORE_REGISTER (regno)) return; size = REGISTER_RAW_SIZE(regno); buf = alloca (size); store_signed_integer (buf, size, (LONGEST) val); /* If we have a valid copy of the register, and new value == old value, then don't bother doing the actual store. */ if (register_valid [regno]) { if (memcmp (®isters[REGISTER_BYTE (regno)], buf, size) == 0) return; } target_prepare_to_store (); memcpy (®isters[REGISTER_BYTE (regno)], buf, size); register_valid [regno] = 1; target_store_registers (regno); } /* Record that register REGNO contains VAL. This is used when the value is obtained from the inferior or core dump, so there is no need to store the value there. */ void supply_register (regno, val) int regno; char *val; { register_valid[regno] = 1; memcpy (®isters[REGISTER_BYTE (regno)], val, REGISTER_RAW_SIZE (regno)); /* On some architectures, e.g. HPPA, there are a few stray bits in some registers, that the rest of the code would like to ignore. */ #ifdef CLEAN_UP_REGISTER_VALUE CLEAN_UP_REGISTER_VALUE(regno, ®isters[REGISTER_BYTE(regno)]); #endif } /* 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. */ value read_var_value (var, frame) register struct symbol *var; FRAME frame; { register value v; struct frame_info *fi; struct type *type = SYMBOL_TYPE (var); CORE_ADDR addr; register int len; v = allocate_value (type); VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */ len = TYPE_LENGTH (type); if (frame == 0) frame = 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. */ store_address (VALUE_CONTENTS_RAW (v), len, SYMBOL_VALUE_ADDRESS (var)); VALUE_LVAL (v) = not_lval; return v; case LOC_CONST_BYTES: { char *bytes_addr; bytes_addr = SYMBOL_VALUE_BYTES (var); memcpy (VALUE_CONTENTS_RAW (v), bytes_addr, len); VALUE_LVAL (v) = not_lval; return v; } case LOC_STATIC: addr = SYMBOL_VALUE_ADDRESS (var); break; case LOC_ARG: fi = get_frame_info (frame); if (fi == NULL) return 0; addr = FRAME_ARGS_ADDRESS (fi); if (!addr) { return 0; } addr += SYMBOL_VALUE (var); break; case LOC_REF_ARG: fi = get_frame_info (frame); if (fi == NULL) return 0; addr = FRAME_ARGS_ADDRESS (fi); if (!addr) { return 0; } addr += SYMBOL_VALUE (var); addr = read_memory_unsigned_integer (addr, TARGET_PTR_BIT / TARGET_CHAR_BIT); break; case LOC_LOCAL: case LOC_LOCAL_ARG: fi = get_frame_info (frame); if (fi == NULL) return 0; addr = FRAME_LOCALS_ADDRESS (fi); addr += SYMBOL_VALUE (var); break; case LOC_BASEREG: case LOC_BASEREG_ARG: { char buf[MAX_REGISTER_RAW_SIZE]; get_saved_register (buf, NULL, NULL, frame, SYMBOL_BASEREG (var), NULL); addr = extract_address (buf, REGISTER_RAW_SIZE (SYMBOL_BASEREG (var))); addr += SYMBOL_VALUE (var); break; } case LOC_TYPEDEF: error ("Cannot look up value of a typedef"); break; case LOC_BLOCK: VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); return v; case LOC_REGISTER: case LOC_REGPARM: case LOC_REGPARM_ADDR: { struct block *b; if (frame == NULL) return 0; b = get_frame_block (frame); v = value_from_register (type, SYMBOL_VALUE (var), frame); if (SYMBOL_CLASS (var) == LOC_REGPARM_ADDR) { addr = *(CORE_ADDR *)VALUE_CONTENTS (v); VALUE_LVAL (v) = lval_memory; } else return v; } break; case LOC_OPTIMIZED_OUT: VALUE_LVAL (v) = not_lval; VALUE_OPTIMIZED_OUT (v) = 1; return v; default: error ("Cannot look up value of a botched symbol."); break; } VALUE_ADDRESS (v) = addr; VALUE_LAZY (v) = 1; return v; } /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */ value value_from_register (type, regnum, frame) struct type *type; int regnum; FRAME frame; { char raw_buffer [MAX_REGISTER_RAW_SIZE]; char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE]; CORE_ADDR addr; int optim; value v = allocate_value (type); int len = TYPE_LENGTH (type); char *value_bytes = 0; int value_bytes_copied = 0; int num_storage_locs; enum lval_type lval; VALUE_REGNO (v) = regnum; num_storage_locs = (len > REGISTER_VIRTUAL_SIZE (regnum) ? ((len - 1) / REGISTER_RAW_SIZE (regnum)) + 1 : 1); if (num_storage_locs > 1 #ifdef GDB_TARGET_IS_H8500 || TYPE_CODE (type) == TYPE_CODE_PTR #endif ) { /* Value spread across multiple storage locations. */ int local_regnum; int mem_stor = 0, reg_stor = 0; int mem_tracking = 1; CORE_ADDR last_addr = 0; CORE_ADDR first_addr; value_bytes = (char *) alloca (len + MAX_REGISTER_RAW_SIZE); /* Copy all of the data out, whereever it may be. */ #ifdef GDB_TARGET_IS_H8500 /* This piece of hideosity is required because the H8500 treats registers differently depending upon whether they are used as pointers or not. As a pointer, a register needs to have a page register tacked onto the front. An alternate way to do this would be to have gcc output different register numbers for the pointer & non-pointer form of the register. But, it doesn't, so we're stuck with this. */ if (TYPE_CODE (type) == TYPE_CODE_PTR && len > 2) { int page_regnum; switch (regnum) { case R0_REGNUM: case R1_REGNUM: case R2_REGNUM: case R3_REGNUM: page_regnum = SEG_D_REGNUM; break; case R4_REGNUM: case R5_REGNUM: page_regnum = SEG_E_REGNUM; break; case R6_REGNUM: case R7_REGNUM: page_regnum = SEG_T_REGNUM; break; } value_bytes[0] = 0; get_saved_register (value_bytes + 1, &optim, &addr, frame, page_regnum, &lval); if (lval == lval_register) reg_stor++; else mem_stor++; first_addr = addr; last_addr = addr; get_saved_register (value_bytes + 2, &optim, &addr, frame, regnum, &lval); if (lval == lval_register) reg_stor++; else { mem_stor++; mem_tracking = mem_tracking && (addr == last_addr); } last_addr = addr; } else #endif /* GDB_TARGET_IS_H8500 */ for (local_regnum = regnum; value_bytes_copied < len; (value_bytes_copied += REGISTER_RAW_SIZE (local_regnum), ++local_regnum)) { get_saved_register (value_bytes + value_bytes_copied, &optim, &addr, frame, local_regnum, &lval); if (regnum == local_regnum) first_addr = addr; if (lval == lval_register) reg_stor++; else { mem_stor++; mem_tracking = (mem_tracking && (regnum == local_regnum || addr == last_addr)); } last_addr = addr; } if ((reg_stor && mem_stor) || (mem_stor && !mem_tracking)) /* Mixed storage; all of the hassle we just went through was for some good purpose. */ { VALUE_LVAL (v) = lval_reg_frame_relative; VALUE_FRAME (v) = FRAME_FP (frame); VALUE_FRAME_REGNUM (v) = regnum; } else if (mem_stor) { VALUE_LVAL (v) = lval_memory; VALUE_ADDRESS (v) = first_addr; } else if (reg_stor) { VALUE_LVAL (v) = lval_register; VALUE_ADDRESS (v) = first_addr; } else fatal ("value_from_register: Value not stored anywhere!"); VALUE_OPTIMIZED_OUT (v) = optim; /* Any structure stored in more than one register will always be an integral number of registers. Otherwise, you'd need to do some fiddling with the last register copied here for little endian machines. */ /* Copy into the contents section of the value. */ memcpy (VALUE_CONTENTS_RAW (v), value_bytes, len); /* Finally do any conversion necessary when extracting this type from more than one register. */ #ifdef REGISTER_CONVERT_TO_TYPE REGISTER_CONVERT_TO_TYPE(regnum, type, VALUE_CONTENTS_RAW(v)); #endif return v; } /* Data is completely contained within a single register. Locate the register's contents in a real register or in core; read the data in raw format. */ get_saved_register (raw_buffer, &optim, &addr, frame, regnum, &lval); VALUE_OPTIMIZED_OUT (v) = optim; VALUE_LVAL (v) = lval; VALUE_ADDRESS (v) = addr; /* Convert the raw contents to virtual contents. (Just copy them if the formats are the same.) */ REGISTER_CONVERT_TO_VIRTUAL (regnum, raw_buffer, virtual_buffer); if (REGISTER_CONVERTIBLE (regnum)) { /* When the raw and virtual formats differ, the virtual format corresponds to a specific data type. If we want that type, copy the data into the value. Otherwise, do a type-conversion. */ if (type != REGISTER_VIRTUAL_TYPE (regnum)) { /* eg a variable of type `float' in a 68881 register with raw type `extended' and virtual type `double'. Fetch it as a `double' and then convert to `float'. */ v = allocate_value (REGISTER_VIRTUAL_TYPE (regnum)); memcpy (VALUE_CONTENTS_RAW (v), virtual_buffer, len); v = value_cast (type, v); } else memcpy (VALUE_CONTENTS_RAW (v), virtual_buffer, len); } else { /* Raw and virtual formats are the same for this register. */ #if TARGET_BYTE_ORDER == BIG_ENDIAN if (len < REGISTER_RAW_SIZE (regnum)) { /* Big-endian, and we want less than full size. */ VALUE_OFFSET (v) = REGISTER_RAW_SIZE (regnum) - len; } #endif memcpy (VALUE_CONTENTS_RAW (v), virtual_buffer + VALUE_OFFSET (v), len); } return v; } /* 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. */ value locate_var_value (var, frame) register struct symbol *var; FRAME frame; { CORE_ADDR addr = 0; struct type *type = SYMBOL_TYPE (var); 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_SOURCE_NAME (var)); if (VALUE_LAZY (lazy_value) || TYPE_CODE (type) == TYPE_CODE_FUNC) { addr = VALUE_ADDRESS (lazy_value); return value_from_longest (lookup_pointer_type (type), (LONGEST) addr); } /* Not a memory address; check what the problem was. */ switch (VALUE_LVAL (lazy_value)) { case lval_register: case lval_reg_frame_relative: error ("Address requested for identifier \"%s\" which is in a register.", SYMBOL_SOURCE_NAME (var)); break; default: error ("Can't take address of \"%s\" which isn't an lvalue.", SYMBOL_SOURCE_NAME (var)); break; } return 0; /* For lint -- never reached */ }