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697 lines
19 KiB
C
697 lines
19 KiB
C
/* Find a variable's value in memory, for GDB, the GNU debugger.
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Copyright (C) 1986, 1987, 1989 Free Software Foundation, Inc.
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This file is part of GDB.
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GDB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 1, or (at your option)
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any later version.
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GDB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GDB; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include <stdio.h>
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#include "defs.h"
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#include "param.h"
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#include "symtab.h"
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#include "frame.h"
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#include "value.h"
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#include "gdbcore.h"
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#include "inferior.h"
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#include "target.h"
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#if !defined (GET_SAVED_REGISTER)
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/* Return the address in which frame FRAME's value of register REGNUM
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has been saved in memory. Or return zero if it has not been saved.
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If REGNUM specifies the SP, the value we return is actually
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the SP value, not an address where it was saved. */
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CORE_ADDR
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find_saved_register (frame, regnum)
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FRAME frame;
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int regnum;
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{
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struct frame_info *fi;
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struct frame_saved_regs saved_regs;
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register FRAME frame1 = 0;
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register CORE_ADDR addr = 0;
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if (frame == 0) /* No regs saved if want current frame */
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return 0;
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#ifdef HAVE_REGISTER_WINDOWS
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/* We assume that a register in a register window will only be saved
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in one place (since the name changes and/or disappears as you go
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towards inner frames), so we only call get_frame_saved_regs on
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the current frame. This is directly in contradiction to the
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usage below, which assumes that registers used in a frame must be
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saved in a lower (more interior) frame. This change is a result
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of working on a register window machine; get_frame_saved_regs
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always returns the registers saved within a frame, within the
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context (register namespace) of that frame. */
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/* However, note that we don't want this to return anything if
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nothing is saved (if there's a frame inside of this one). Also,
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callers to this routine asking for the stack pointer want the
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stack pointer saved for *this* frame; this is returned from the
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next frame. */
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if (REGISTER_IN_WINDOW_P(regnum))
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{
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frame1 = get_next_frame (frame);
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if (!frame1) return 0; /* Registers of this frame are
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active. */
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/* Get the SP from the next frame in; it will be this
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current frame. */
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if (regnum != SP_REGNUM)
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frame1 = frame;
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fi = get_frame_info (frame1);
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get_frame_saved_regs (fi, &saved_regs);
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return saved_regs.regs[regnum]; /* ... which might be zero */
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}
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#endif /* HAVE_REGISTER_WINDOWS */
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/* Note that this next routine assumes that registers used in
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frame x will be saved only in the frame that x calls and
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frames interior to it. This is not true on the sparc, but the
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above macro takes care of it, so we should be all right. */
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while (1)
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{
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QUIT;
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frame1 = get_prev_frame (frame1);
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if (frame1 == 0 || frame1 == frame)
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break;
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fi = get_frame_info (frame1);
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get_frame_saved_regs (fi, &saved_regs);
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if (saved_regs.regs[regnum])
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addr = saved_regs.regs[regnum];
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}
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return addr;
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}
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/* Find register number REGNUM relative to FRAME and put its
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(raw) contents in *RAW_BUFFER. Set *OPTIMIZED if the variable
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was optimized out (and thus can't be fetched). Set *LVAL to
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lval_memory, lval_register, or not_lval, depending on whether the
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value was fetched from memory, from a register, or in a strange
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and non-modifiable way (e.g. a frame pointer which was calculated
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rather than fetched). Set *ADDRP to the address, either in memory
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on as a REGISTER_BYTE offset into the registers array.
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Note that this implementation never sets *LVAL to not_lval. But
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it can be replaced by defining GET_SAVED_REGISTER and supplying
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your own.
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The argument RAW_BUFFER must point to aligned memory. */
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void
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get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval)
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char *raw_buffer;
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int *optimized;
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CORE_ADDR *addrp;
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FRAME frame;
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int regnum;
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enum lval_type *lval;
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{
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CORE_ADDR addr;
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/* Normal systems don't optimize out things with register numbers. */
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if (optimized != NULL)
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*optimized = 0;
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addr = find_saved_register (frame, regnum);
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if (addr != NULL)
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{
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if (lval != NULL)
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*lval = lval_memory;
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if (regnum == SP_REGNUM)
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{
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if (raw_buffer != NULL)
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*(CORE_ADDR *)raw_buffer = addr;
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if (addrp != NULL)
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*addrp = 0;
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return;
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}
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if (raw_buffer != NULL)
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read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (regnum));
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}
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else
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{
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if (lval != NULL)
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*lval = lval_register;
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addr = REGISTER_BYTE (regnum);
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if (raw_buffer != NULL)
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read_register_gen (regnum, raw_buffer);
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}
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if (addrp != NULL)
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*addrp = addr;
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}
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#endif /* GET_SAVED_REGISTER. */
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/* Copy the bytes of register REGNUM, relative to the current stack frame,
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into our memory at MYADDR, in target byte order.
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The number of bytes copied is REGISTER_RAW_SIZE (REGNUM).
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Returns 1 if could not be read, 0 if could. */
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int
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read_relative_register_raw_bytes (regnum, myaddr)
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int regnum;
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char *myaddr;
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{
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int optim;
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if (regnum == FP_REGNUM && selected_frame)
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{
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bcopy (&FRAME_FP(selected_frame), myaddr, sizeof (CORE_ADDR));
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SWAP_TARGET_AND_HOST (myaddr, sizeof (CORE_ADDR)); /* in target order */
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return 0;
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}
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get_saved_register (myaddr, &optim, (CORE_ADDR) NULL, selected_frame,
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regnum, (enum lval_type *)NULL);
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return optim;
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}
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/* Return a `value' with the contents of register REGNUM
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in its virtual format, with the type specified by
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REGISTER_VIRTUAL_TYPE. */
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value
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value_of_register (regnum)
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int regnum;
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{
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CORE_ADDR addr;
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int optim;
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register value val;
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char raw_buffer[MAX_REGISTER_RAW_SIZE];
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char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE];
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enum lval_type lval;
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get_saved_register (raw_buffer, &optim, &addr,
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selected_frame, regnum, &lval);
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target_convert_to_virtual (regnum, raw_buffer, virtual_buffer);
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val = allocate_value (REGISTER_VIRTUAL_TYPE (regnum));
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bcopy (virtual_buffer, VALUE_CONTENTS_RAW (val),
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REGISTER_VIRTUAL_SIZE (regnum));
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VALUE_LVAL (val) = lval;
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VALUE_ADDRESS (val) = addr;
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VALUE_REGNO (val) = regnum;
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VALUE_OPTIMIZED_OUT (val) = optim;
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return val;
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}
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/* Low level examining and depositing of registers.
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The caller is responsible for making
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sure that the inferior is stopped before calling the fetching routines,
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or it will get garbage. (a change from GDB version 3, in which
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the caller got the value from the last stop). */
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/* Contents of the registers in target byte order.
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We allocate some extra slop since we do a lot of bcopy's around `registers',
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and failing-soft is better than failing hard. */
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char registers[REGISTER_BYTES + /* SLOP */ 256];
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/* Nonzero if that register has been fetched. */
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char register_valid[NUM_REGS];
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/* Indicate that registers may have changed, so invalidate the cache. */
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void
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registers_changed ()
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{
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int i;
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for (i = 0; i < NUM_REGS; i++)
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register_valid[i] = 0;
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}
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/* Indicate that all registers have been fetched, so mark them all valid. */
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void
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registers_fetched ()
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{
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int i;
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for (i = 0; i < NUM_REGS; i++)
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register_valid[i] = 1;
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}
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/* Copy LEN bytes of consecutive data from registers
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starting with the REGBYTE'th byte of register data
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into memory at MYADDR. */
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void
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read_register_bytes (regbyte, myaddr, len)
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int regbyte;
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char *myaddr;
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int len;
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{
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/* Fetch all registers. */
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int i;
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for (i = 0; i < NUM_REGS; i++)
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if (!register_valid[i])
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{
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target_fetch_registers (-1);
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break;
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}
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if (myaddr != NULL)
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bcopy (®isters[regbyte], myaddr, len);
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}
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/* Read register REGNO into memory at MYADDR, which must be large enough
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for REGISTER_RAW_BYTES (REGNO). Target byte-order.
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If the register is known to be the size of a CORE_ADDR or smaller,
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read_register can be used instead. */
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void
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read_register_gen (regno, myaddr)
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int regno;
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char *myaddr;
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{
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if (!register_valid[regno])
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target_fetch_registers (regno);
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bcopy (®isters[REGISTER_BYTE (regno)], myaddr, REGISTER_RAW_SIZE (regno));
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}
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/* Copy LEN bytes of consecutive data from memory at MYADDR
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into registers starting with the REGBYTE'th byte of register data. */
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void
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write_register_bytes (regbyte, myaddr, len)
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int regbyte;
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char *myaddr;
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int len;
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{
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/* Make sure the entire registers array is valid. */
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read_register_bytes (0, (char *)NULL, REGISTER_BYTES);
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bcopy (myaddr, ®isters[regbyte], len);
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target_store_registers (-1);
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}
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/* Return the contents of register REGNO, regarding it as an integer. */
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CORE_ADDR
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read_register (regno)
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int regno;
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{
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int reg;
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if (!register_valid[regno])
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target_fetch_registers (regno);
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/* FIXME, this loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */
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reg = *(int *) ®isters[REGISTER_BYTE (regno)];
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SWAP_TARGET_AND_HOST (®, sizeof (int));
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return reg;
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}
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/* Registers we shouldn't try to store. */
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#if !defined (CANNOT_STORE_REGISTER)
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#define CANNOT_STORE_REGISTER(regno) 0
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#endif
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/* Store VALUE in the register number REGNO, regarded as an integer. */
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void
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write_register (regno, val)
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int regno, val;
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{
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/* On the sparc, writing %g0 is a no-op, so we don't even want to change
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the registers array if something writes to this register. */
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if (CANNOT_STORE_REGISTER (regno))
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return;
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SWAP_TARGET_AND_HOST (&val, sizeof (int));
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target_prepare_to_store ();
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register_valid [regno] = 1;
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/* FIXME, this loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */
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/* FIXME, this depends on REGISTER_BYTE (regno) being aligned for host */
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*(int *) ®isters[REGISTER_BYTE (regno)] = val;
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target_store_registers (regno);
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}
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/* Record that register REGNO contains VAL.
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This is used when the value is obtained from the inferior or core dump,
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so there is no need to store the value there. */
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void
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supply_register (regno, val)
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int regno;
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char *val;
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{
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register_valid[regno] = 1;
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bcopy (val, ®isters[REGISTER_BYTE (regno)], REGISTER_RAW_SIZE (regno));
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}
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/* Given a struct symbol for a variable,
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and a stack frame id, read the value of the variable
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and return a (pointer to a) struct value containing the value.
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If the variable cannot be found, return a zero pointer.
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If FRAME is NULL, use the selected_frame. */
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value
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read_var_value (var, frame)
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register struct symbol *var;
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FRAME frame;
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{
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register value v;
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struct frame_info *fi;
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struct type *type = SYMBOL_TYPE (var);
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CORE_ADDR addr;
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int val;
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register int len;
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v = allocate_value (type);
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VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */
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len = TYPE_LENGTH (type);
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if (frame == 0) frame = selected_frame;
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switch (SYMBOL_CLASS (var))
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{
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case LOC_CONST:
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val = SYMBOL_VALUE (var);
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bcopy (&val, VALUE_CONTENTS_RAW (v), len);
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SWAP_TARGET_AND_HOST (VALUE_CONTENTS_RAW (v), len);
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VALUE_LVAL (v) = not_lval;
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return v;
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case LOC_LABEL:
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addr = SYMBOL_VALUE_ADDRESS (var);
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bcopy (&addr, VALUE_CONTENTS_RAW (v), len);
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SWAP_TARGET_AND_HOST (VALUE_CONTENTS_RAW (v), len);
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VALUE_LVAL (v) = not_lval;
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return v;
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case LOC_CONST_BYTES:
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addr = SYMBOL_VALUE_ADDRESS (var);
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bcopy (addr, VALUE_CONTENTS_RAW (v), len);
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VALUE_LVAL (v) = not_lval;
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return v;
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case LOC_STATIC:
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case LOC_EXTERNAL:
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addr = SYMBOL_VALUE_ADDRESS (var);
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break;
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/* Nonzero if a struct which is located in a register or a LOC_ARG
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really contains
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the address of the struct, not the struct itself. GCC_P is nonzero
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if the function was compiled with GCC. */
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#if !defined (REG_STRUCT_HAS_ADDR)
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#define REG_STRUCT_HAS_ADDR(gcc_p) 0
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#endif
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case LOC_ARG:
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fi = get_frame_info (frame);
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if (fi == NULL)
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return 0;
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addr = FRAME_ARGS_ADDRESS (fi);
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if (!addr) {
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return 0;
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}
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addr += SYMBOL_VALUE (var);
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break;
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case LOC_REF_ARG:
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fi = get_frame_info (frame);
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if (fi == NULL)
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return 0;
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addr = FRAME_ARGS_ADDRESS (fi);
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if (!addr) {
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return 0;
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}
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addr += SYMBOL_VALUE (var);
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addr = read_memory_integer (addr, sizeof (CORE_ADDR));
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break;
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case LOC_LOCAL:
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case LOC_LOCAL_ARG:
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fi = get_frame_info (frame);
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if (fi == NULL)
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return 0;
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addr = SYMBOL_VALUE (var) + FRAME_LOCALS_ADDRESS (fi);
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break;
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case LOC_TYPEDEF:
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error ("Cannot look up value of a typedef");
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break;
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case LOC_BLOCK:
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VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var));
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return v;
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case LOC_REGISTER:
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case LOC_REGPARM:
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{
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struct block *b;
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if (frame == NULL)
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return 0;
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b = get_frame_block (frame);
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v = value_from_register (type, SYMBOL_VALUE (var), frame);
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if (REG_STRUCT_HAS_ADDR(b->gcc_compile_flag)
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&& TYPE_CODE (type) == TYPE_CODE_STRUCT)
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addr = *(CORE_ADDR *)VALUE_CONTENTS (v);
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else
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return v;
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}
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break;
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default:
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error ("Cannot look up value of a botched symbol.");
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break;
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}
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VALUE_ADDRESS (v) = addr;
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VALUE_LAZY (v) = 1;
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return v;
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}
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/* Return a value of type TYPE, stored in register REGNUM, in frame
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FRAME. */
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value
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value_from_register (type, regnum, frame)
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struct type *type;
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int regnum;
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FRAME frame;
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{
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char raw_buffer [MAX_REGISTER_RAW_SIZE];
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char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE];
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CORE_ADDR addr;
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int optim;
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value v = allocate_value (type);
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int len = TYPE_LENGTH (type);
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char *value_bytes = 0;
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int value_bytes_copied = 0;
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int num_storage_locs;
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enum lval_type lval;
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VALUE_REGNO (v) = regnum;
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num_storage_locs = (len > REGISTER_VIRTUAL_SIZE (regnum) ?
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((len - 1) / REGISTER_RAW_SIZE (regnum)) + 1 :
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1);
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if (num_storage_locs > 1)
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{
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/* Value spread across multiple storage locations. */
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int local_regnum;
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int mem_stor = 0, reg_stor = 0;
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int mem_tracking = 1;
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CORE_ADDR last_addr = 0;
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CORE_ADDR first_addr;
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value_bytes = (char *) alloca (len + MAX_REGISTER_RAW_SIZE);
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/* Copy all of the data out, whereever it may be. */
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for (local_regnum = regnum;
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value_bytes_copied < len;
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(value_bytes_copied += REGISTER_RAW_SIZE (local_regnum),
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++local_regnum))
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{
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get_saved_register (value_bytes + value_bytes_copied,
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&optim,
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&addr,
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frame,
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local_regnum,
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&lval);
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if (lval == lval_register)
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reg_stor++;
|
||
else
|
||
{
|
||
mem_stor++;
|
||
|
||
if (regnum == local_regnum)
|
||
first_addr = addr;
|
||
|
||
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. */
|
||
bcopy (value_bytes, VALUE_CONTENTS_RAW (v), len);
|
||
|
||
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.) */
|
||
|
||
target_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));
|
||
bcopy (virtual_buffer, VALUE_CONTENTS_RAW (v), len);
|
||
v = value_cast (type, v);
|
||
}
|
||
else
|
||
bcopy (virtual_buffer, VALUE_CONTENTS_RAW (v), 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
|
||
|
||
bcopy (virtual_buffer + VALUE_OFFSET (v),
|
||
VALUE_CONTENTS_RAW (v), len);
|
||
}
|
||
|
||
return v;
|
||
}
|
||
|
||
/* Given a struct symbol for a variable,
|
||
and a stack frame id,
|
||
return a (pointer to a) struct value containing the variable's address. */
|
||
|
||
value
|
||
locate_var_value (var, frame)
|
||
register struct symbol *var;
|
||
FRAME frame;
|
||
{
|
||
CORE_ADDR addr = 0;
|
||
struct type *type = SYMBOL_TYPE (var);
|
||
struct type *result_type;
|
||
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_NAME (var));
|
||
|
||
if (VALUE_LAZY (lazy_value))
|
||
{
|
||
addr = VALUE_ADDRESS (lazy_value);
|
||
|
||
/* C++: The "address" of a reference should yield the address
|
||
* of the object pointed to. So force an extra de-reference. */
|
||
|
||
if (TYPE_CODE (type) == TYPE_CODE_REF)
|
||
{
|
||
char *buf = alloca (TYPE_LENGTH (type));
|
||
read_memory (addr, buf, TYPE_LENGTH (type));
|
||
addr = unpack_long (type, buf);
|
||
type = TYPE_TARGET_TYPE (type);
|
||
}
|
||
|
||
/* Address of an array is of the type of address of it's elements. */
|
||
result_type =
|
||
lookup_pointer_type (TYPE_CODE (type) == TYPE_CODE_ARRAY ?
|
||
TYPE_TARGET_TYPE (type) : type);
|
||
|
||
return value_cast (result_type,
|
||
value_from_long (builtin_type_long, (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_NAME (var));
|
||
break;
|
||
|
||
default:
|
||
error ("Can't take address of \"%s\" which isn't an lvalue.",
|
||
SYMBOL_NAME (var));
|
||
break;
|
||
}
|
||
return 0; /* For lint -- never reached */
|
||
}
|