846 lines
24 KiB
C
846 lines
24 KiB
C
/* DWARF 2 location expression support for GDB.
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Copyright (C) 2003, 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
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Contributed by Daniel Jacobowitz, MontaVista Software, Inc.
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This file is part of GDB.
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This program 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 3 of the License, or
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(at your option) any later version.
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This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "ui-out.h"
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#include "value.h"
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#include "frame.h"
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#include "gdbcore.h"
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#include "target.h"
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#include "inferior.h"
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#include "ax.h"
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#include "ax-gdb.h"
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#include "regcache.h"
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#include "objfiles.h"
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#include "exceptions.h"
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#include "block.h"
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#include "dwarf2.h"
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#include "dwarf2expr.h"
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#include "dwarf2loc.h"
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#include "dwarf2-frame.h"
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#include "gdb_string.h"
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#include "gdb_assert.h"
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/* A helper function for dealing with location lists. Given a
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symbol baton (BATON) and a pc value (PC), find the appropriate
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location expression, set *LOCEXPR_LENGTH, and return a pointer
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to the beginning of the expression. Returns NULL on failure.
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For now, only return the first matching location expression; there
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can be more than one in the list. */
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static gdb_byte *
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find_location_expression (struct dwarf2_loclist_baton *baton,
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size_t *locexpr_length, CORE_ADDR pc)
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{
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CORE_ADDR low, high;
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gdb_byte *loc_ptr, *buf_end;
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int length;
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struct objfile *objfile = dwarf2_per_cu_objfile (baton->per_cu);
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struct gdbarch *gdbarch = get_objfile_arch (objfile);
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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unsigned int addr_size = dwarf2_per_cu_addr_size (baton->per_cu);
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CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
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/* Adjust base_address for relocatable objects. */
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CORE_ADDR base_offset = ANOFFSET (objfile->section_offsets,
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SECT_OFF_TEXT (objfile));
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CORE_ADDR base_address = baton->base_address + base_offset;
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loc_ptr = baton->data;
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buf_end = baton->data + baton->size;
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while (1)
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{
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if (buf_end - loc_ptr < 2 * addr_size)
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error (_("find_location_expression: Corrupted DWARF expression."));
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low = extract_unsigned_integer (loc_ptr, addr_size, byte_order);
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loc_ptr += addr_size;
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/* A base-address-selection entry. */
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if (low == base_mask)
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{
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base_address = dwarf2_read_address (gdbarch,
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loc_ptr, buf_end, addr_size);
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loc_ptr += addr_size;
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continue;
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}
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high = extract_unsigned_integer (loc_ptr, addr_size, byte_order);
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loc_ptr += addr_size;
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/* An end-of-list entry. */
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if (low == 0 && high == 0)
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return NULL;
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/* Otherwise, a location expression entry. */
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low += base_address;
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high += base_address;
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length = extract_unsigned_integer (loc_ptr, 2, byte_order);
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loc_ptr += 2;
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if (pc >= low && pc < high)
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{
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*locexpr_length = length;
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return loc_ptr;
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}
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loc_ptr += length;
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}
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}
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/* This is the baton used when performing dwarf2 expression
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evaluation. */
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struct dwarf_expr_baton
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{
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struct frame_info *frame;
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struct objfile *objfile;
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};
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/* Helper functions for dwarf2_evaluate_loc_desc. */
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/* Using the frame specified in BATON, return the value of register
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REGNUM, treated as a pointer. */
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static CORE_ADDR
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dwarf_expr_read_reg (void *baton, int dwarf_regnum)
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{
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struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
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struct gdbarch *gdbarch = get_frame_arch (debaton->frame);
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CORE_ADDR result;
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int regnum;
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regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum);
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result = address_from_register (builtin_type (gdbarch)->builtin_data_ptr,
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regnum, debaton->frame);
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return result;
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}
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/* Read memory at ADDR (length LEN) into BUF. */
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static void
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dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
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{
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read_memory (addr, buf, len);
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}
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/* Using the frame specified in BATON, find the location expression
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describing the frame base. Return a pointer to it in START and
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its length in LENGTH. */
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static void
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dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length)
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{
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/* FIXME: cagney/2003-03-26: This code should be using
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get_frame_base_address(), and then implement a dwarf2 specific
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this_base method. */
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struct symbol *framefunc;
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struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
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/* Use block_linkage_function, which returns a real (not inlined)
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function, instead of get_frame_function, which may return an
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inlined function. */
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framefunc = block_linkage_function (get_frame_block (debaton->frame, NULL));
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/* If we found a frame-relative symbol then it was certainly within
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some function associated with a frame. If we can't find the frame,
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something has gone wrong. */
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gdb_assert (framefunc != NULL);
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if (SYMBOL_LOCATION_BATON (framefunc) == NULL)
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*start = NULL;
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else if (SYMBOL_COMPUTED_OPS (framefunc) == &dwarf2_loclist_funcs)
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{
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struct dwarf2_loclist_baton *symbaton;
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struct frame_info *frame = debaton->frame;
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symbaton = SYMBOL_LOCATION_BATON (framefunc);
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*start = find_location_expression (symbaton, length,
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get_frame_address_in_block (frame));
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}
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else
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{
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struct dwarf2_locexpr_baton *symbaton;
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symbaton = SYMBOL_LOCATION_BATON (framefunc);
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if (symbaton != NULL)
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{
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*length = symbaton->size;
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*start = symbaton->data;
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}
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else
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*start = NULL;
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}
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if (*start == NULL)
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error (_("Could not find the frame base for \"%s\"."),
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SYMBOL_NATURAL_NAME (framefunc));
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}
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/* Helper function for dwarf2_evaluate_loc_desc. Computes the CFA for
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the frame in BATON. */
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static CORE_ADDR
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dwarf_expr_frame_cfa (void *baton)
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{
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struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
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return dwarf2_frame_cfa (debaton->frame);
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}
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/* Using the objfile specified in BATON, find the address for the
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current thread's thread-local storage with offset OFFSET. */
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static CORE_ADDR
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dwarf_expr_tls_address (void *baton, CORE_ADDR offset)
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{
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struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
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return target_translate_tls_address (debaton->objfile, offset);
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}
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struct piece_closure
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{
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/* The number of pieces used to describe this variable. */
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int n_pieces;
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/* The architecture, used only for DWARF_VALUE_STACK. */
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struct gdbarch *arch;
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/* The pieces themselves. */
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struct dwarf_expr_piece *pieces;
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};
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/* Allocate a closure for a value formed from separately-described
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PIECES. */
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static struct piece_closure *
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allocate_piece_closure (int n_pieces, struct dwarf_expr_piece *pieces,
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struct gdbarch *arch)
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{
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struct piece_closure *c = XZALLOC (struct piece_closure);
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c->n_pieces = n_pieces;
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c->arch = arch;
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c->pieces = XCALLOC (n_pieces, struct dwarf_expr_piece);
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memcpy (c->pieces, pieces, n_pieces * sizeof (struct dwarf_expr_piece));
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return c;
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}
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static void
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read_pieced_value (struct value *v)
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{
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int i;
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long offset = 0;
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gdb_byte *contents;
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struct piece_closure *c = (struct piece_closure *) value_computed_closure (v);
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struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (v));
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contents = value_contents_raw (v);
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for (i = 0; i < c->n_pieces; i++)
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{
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struct dwarf_expr_piece *p = &c->pieces[i];
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switch (p->location)
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{
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case DWARF_VALUE_REGISTER:
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{
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struct gdbarch *arch = get_frame_arch (frame);
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bfd_byte regval[MAX_REGISTER_SIZE];
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int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch,
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p->v.value);
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get_frame_register (frame, gdb_regnum, regval);
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memcpy (contents + offset, regval, p->size);
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}
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break;
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case DWARF_VALUE_MEMORY:
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read_memory (p->v.value, contents + offset, p->size);
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break;
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case DWARF_VALUE_STACK:
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{
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gdb_byte bytes[sizeof (ULONGEST)];
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size_t n;
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int addr_size = gdbarch_addr_bit (c->arch) / 8;
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store_unsigned_integer (bytes, addr_size,
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gdbarch_byte_order (c->arch),
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p->v.value);
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n = p->size;
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if (n > addr_size)
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n = addr_size;
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memcpy (contents + offset, bytes, n);
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}
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break;
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case DWARF_VALUE_LITERAL:
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{
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size_t n = p->size;
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if (n > p->v.literal.length)
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n = p->v.literal.length;
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memcpy (contents + offset, p->v.literal.data, n);
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}
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break;
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default:
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internal_error (__FILE__, __LINE__, _("invalid location type"));
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}
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offset += p->size;
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}
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}
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static void
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write_pieced_value (struct value *to, struct value *from)
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{
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int i;
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long offset = 0;
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gdb_byte *contents;
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struct piece_closure *c = (struct piece_closure *) value_computed_closure (to);
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struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (to));
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if (frame == NULL)
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{
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set_value_optimized_out (to, 1);
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return;
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}
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contents = value_contents_raw (from);
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for (i = 0; i < c->n_pieces; i++)
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{
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struct dwarf_expr_piece *p = &c->pieces[i];
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switch (p->location)
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{
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case DWARF_VALUE_REGISTER:
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{
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struct gdbarch *arch = get_frame_arch (frame);
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int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.value);
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put_frame_register (frame, gdb_regnum, contents + offset);
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}
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break;
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case DWARF_VALUE_MEMORY:
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write_memory (p->v.value, contents + offset, p->size);
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break;
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default:
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set_value_optimized_out (to, 1);
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return;
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}
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offset += p->size;
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}
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}
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static void *
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copy_pieced_value_closure (struct value *v)
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{
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struct piece_closure *c = (struct piece_closure *) value_computed_closure (v);
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return allocate_piece_closure (c->n_pieces, c->pieces, c->arch);
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}
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static void
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free_pieced_value_closure (struct value *v)
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{
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struct piece_closure *c = (struct piece_closure *) value_computed_closure (v);
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xfree (c->pieces);
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xfree (c);
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}
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/* Functions for accessing a variable described by DW_OP_piece. */
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static struct lval_funcs pieced_value_funcs = {
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read_pieced_value,
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write_pieced_value,
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copy_pieced_value_closure,
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free_pieced_value_closure
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};
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/* Evaluate a location description, starting at DATA and with length
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SIZE, to find the current location of variable VAR in the context
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of FRAME. */
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static struct value *
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dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame,
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gdb_byte *data, unsigned short size,
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struct dwarf2_per_cu_data *per_cu)
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{
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struct value *retval;
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struct dwarf_expr_baton baton;
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struct dwarf_expr_context *ctx;
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struct cleanup *old_chain;
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if (size == 0)
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{
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retval = allocate_value (SYMBOL_TYPE (var));
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VALUE_LVAL (retval) = not_lval;
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set_value_optimized_out (retval, 1);
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return retval;
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}
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baton.frame = frame;
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baton.objfile = dwarf2_per_cu_objfile (per_cu);
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ctx = new_dwarf_expr_context ();
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old_chain = make_cleanup_free_dwarf_expr_context (ctx);
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ctx->gdbarch = get_objfile_arch (baton.objfile);
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ctx->addr_size = dwarf2_per_cu_addr_size (per_cu);
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ctx->baton = &baton;
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ctx->read_reg = dwarf_expr_read_reg;
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ctx->read_mem = dwarf_expr_read_mem;
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ctx->get_frame_base = dwarf_expr_frame_base;
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ctx->get_frame_cfa = dwarf_expr_frame_cfa;
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ctx->get_tls_address = dwarf_expr_tls_address;
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dwarf_expr_eval (ctx, data, size);
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if (ctx->num_pieces > 0)
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{
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struct piece_closure *c;
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struct frame_id frame_id = get_frame_id (frame);
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c = allocate_piece_closure (ctx->num_pieces, ctx->pieces, ctx->gdbarch);
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retval = allocate_computed_value (SYMBOL_TYPE (var),
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&pieced_value_funcs,
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c);
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VALUE_FRAME_ID (retval) = frame_id;
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}
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else
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{
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switch (ctx->location)
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{
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case DWARF_VALUE_REGISTER:
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{
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struct gdbarch *arch = get_frame_arch (frame);
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CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0);
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int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_regnum);
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retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame);
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}
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break;
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case DWARF_VALUE_MEMORY:
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{
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CORE_ADDR address = dwarf_expr_fetch (ctx, 0);
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retval = allocate_value (SYMBOL_TYPE (var));
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VALUE_LVAL (retval) = lval_memory;
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set_value_lazy (retval, 1);
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set_value_stack (retval, 1);
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set_value_address (retval, address);
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}
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break;
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case DWARF_VALUE_STACK:
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{
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gdb_byte bytes[sizeof (ULONGEST)];
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ULONGEST value = (ULONGEST) dwarf_expr_fetch (ctx, 0);
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bfd_byte *contents;
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size_t n = ctx->addr_size;
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store_unsigned_integer (bytes, ctx->addr_size,
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gdbarch_byte_order (ctx->gdbarch),
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value);
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retval = allocate_value (SYMBOL_TYPE (var));
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contents = value_contents_raw (retval);
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if (n > TYPE_LENGTH (SYMBOL_TYPE (var)))
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n = TYPE_LENGTH (SYMBOL_TYPE (var));
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memcpy (contents, bytes, n);
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}
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break;
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case DWARF_VALUE_LITERAL:
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{
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bfd_byte *contents;
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size_t n = ctx->len;
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retval = allocate_value (SYMBOL_TYPE (var));
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contents = value_contents_raw (retval);
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if (n > TYPE_LENGTH (SYMBOL_TYPE (var)))
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n = TYPE_LENGTH (SYMBOL_TYPE (var));
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memcpy (contents, ctx->data, n);
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}
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break;
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default:
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internal_error (__FILE__, __LINE__, _("invalid location type"));
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}
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}
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set_value_initialized (retval, ctx->initialized);
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do_cleanups (old_chain);
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return retval;
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}
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/* Helper functions and baton for dwarf2_loc_desc_needs_frame. */
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struct needs_frame_baton
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{
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int needs_frame;
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};
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/* Reads from registers do require a frame. */
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static CORE_ADDR
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needs_frame_read_reg (void *baton, int regnum)
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{
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struct needs_frame_baton *nf_baton = baton;
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nf_baton->needs_frame = 1;
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return 1;
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}
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/* Reads from memory do not require a frame. */
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static void
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needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
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{
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memset (buf, 0, len);
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}
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/* Frame-relative accesses do require a frame. */
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static void
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needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length)
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{
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static gdb_byte lit0 = DW_OP_lit0;
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struct needs_frame_baton *nf_baton = baton;
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*start = &lit0;
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*length = 1;
|
||
|
||
nf_baton->needs_frame = 1;
|
||
}
|
||
|
||
/* CFA accesses require a frame. */
|
||
|
||
static CORE_ADDR
|
||
needs_frame_frame_cfa (void *baton)
|
||
{
|
||
struct needs_frame_baton *nf_baton = baton;
|
||
nf_baton->needs_frame = 1;
|
||
return 1;
|
||
}
|
||
|
||
/* Thread-local accesses do require a frame. */
|
||
static CORE_ADDR
|
||
needs_frame_tls_address (void *baton, CORE_ADDR offset)
|
||
{
|
||
struct needs_frame_baton *nf_baton = baton;
|
||
nf_baton->needs_frame = 1;
|
||
return 1;
|
||
}
|
||
|
||
/* Return non-zero iff the location expression at DATA (length SIZE)
|
||
requires a frame to evaluate. */
|
||
|
||
static int
|
||
dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size,
|
||
struct dwarf2_per_cu_data *per_cu)
|
||
{
|
||
struct needs_frame_baton baton;
|
||
struct dwarf_expr_context *ctx;
|
||
int in_reg;
|
||
struct cleanup *old_chain;
|
||
|
||
baton.needs_frame = 0;
|
||
|
||
ctx = new_dwarf_expr_context ();
|
||
old_chain = make_cleanup_free_dwarf_expr_context (ctx);
|
||
|
||
ctx->gdbarch = get_objfile_arch (dwarf2_per_cu_objfile (per_cu));
|
||
ctx->addr_size = dwarf2_per_cu_addr_size (per_cu);
|
||
ctx->baton = &baton;
|
||
ctx->read_reg = needs_frame_read_reg;
|
||
ctx->read_mem = needs_frame_read_mem;
|
||
ctx->get_frame_base = needs_frame_frame_base;
|
||
ctx->get_frame_cfa = needs_frame_frame_cfa;
|
||
ctx->get_tls_address = needs_frame_tls_address;
|
||
|
||
dwarf_expr_eval (ctx, data, size);
|
||
|
||
in_reg = ctx->location == DWARF_VALUE_REGISTER;
|
||
|
||
if (ctx->num_pieces > 0)
|
||
{
|
||
int i;
|
||
|
||
/* If the location has several pieces, and any of them are in
|
||
registers, then we will need a frame to fetch them from. */
|
||
for (i = 0; i < ctx->num_pieces; i++)
|
||
if (ctx->pieces[i].location == DWARF_VALUE_REGISTER)
|
||
in_reg = 1;
|
||
}
|
||
|
||
do_cleanups (old_chain);
|
||
|
||
return baton.needs_frame || in_reg;
|
||
}
|
||
|
||
static void
|
||
dwarf2_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch,
|
||
struct agent_expr *ax, struct axs_value *value,
|
||
gdb_byte *data, int size)
|
||
{
|
||
if (size == 0)
|
||
error (_("Symbol \"%s\" has been optimized out."),
|
||
SYMBOL_PRINT_NAME (symbol));
|
||
|
||
if (size == 1
|
||
&& data[0] >= DW_OP_reg0
|
||
&& data[0] <= DW_OP_reg31)
|
||
{
|
||
value->kind = axs_lvalue_register;
|
||
value->u.reg = data[0] - DW_OP_reg0;
|
||
}
|
||
else if (data[0] == DW_OP_regx)
|
||
{
|
||
ULONGEST reg;
|
||
read_uleb128 (data + 1, data + size, ®);
|
||
value->kind = axs_lvalue_register;
|
||
value->u.reg = reg;
|
||
}
|
||
else if (data[0] == DW_OP_fbreg)
|
||
{
|
||
/* And this is worse than just minimal; we should honor the frame base
|
||
as above. */
|
||
int frame_reg;
|
||
LONGEST frame_offset;
|
||
gdb_byte *buf_end;
|
||
|
||
buf_end = read_sleb128 (data + 1, data + size, &frame_offset);
|
||
if (buf_end != data + size)
|
||
error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."),
|
||
SYMBOL_PRINT_NAME (symbol));
|
||
|
||
gdbarch_virtual_frame_pointer (gdbarch,
|
||
ax->scope, &frame_reg, &frame_offset);
|
||
ax_reg (ax, frame_reg);
|
||
ax_const_l (ax, frame_offset);
|
||
ax_simple (ax, aop_add);
|
||
|
||
value->kind = axs_lvalue_memory;
|
||
}
|
||
else if (data[0] >= DW_OP_breg0
|
||
&& data[0] <= DW_OP_breg31)
|
||
{
|
||
unsigned int reg;
|
||
LONGEST offset;
|
||
gdb_byte *buf_end;
|
||
|
||
reg = data[0] - DW_OP_breg0;
|
||
buf_end = read_sleb128 (data + 1, data + size, &offset);
|
||
if (buf_end != data + size)
|
||
error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."),
|
||
reg, SYMBOL_PRINT_NAME (symbol));
|
||
|
||
ax_reg (ax, reg);
|
||
ax_const_l (ax, offset);
|
||
ax_simple (ax, aop_add);
|
||
|
||
value->kind = axs_lvalue_memory;
|
||
}
|
||
else
|
||
error (_("Unsupported DWARF opcode 0x%x in the location of \"%s\"."),
|
||
data[0], SYMBOL_PRINT_NAME (symbol));
|
||
}
|
||
|
||
/* Return the value of SYMBOL in FRAME using the DWARF-2 expression
|
||
evaluator to calculate the location. */
|
||
static struct value *
|
||
locexpr_read_variable (struct symbol *symbol, struct frame_info *frame)
|
||
{
|
||
struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
struct value *val;
|
||
val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size,
|
||
dlbaton->per_cu);
|
||
|
||
return val;
|
||
}
|
||
|
||
/* Return non-zero iff we need a frame to evaluate SYMBOL. */
|
||
static int
|
||
locexpr_read_needs_frame (struct symbol *symbol)
|
||
{
|
||
struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size,
|
||
dlbaton->per_cu);
|
||
}
|
||
|
||
/* Print a natural-language description of SYMBOL to STREAM. */
|
||
static int
|
||
locexpr_describe_location (struct symbol *symbol, struct ui_file *stream)
|
||
{
|
||
/* FIXME: be more extensive. */
|
||
struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
int addr_size = dwarf2_per_cu_addr_size (dlbaton->per_cu);
|
||
|
||
if (dlbaton->size == 1
|
||
&& dlbaton->data[0] >= DW_OP_reg0
|
||
&& dlbaton->data[0] <= DW_OP_reg31)
|
||
{
|
||
struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu);
|
||
struct gdbarch *gdbarch = get_objfile_arch (objfile);
|
||
int regno = gdbarch_dwarf2_reg_to_regnum (gdbarch,
|
||
dlbaton->data[0] - DW_OP_reg0);
|
||
fprintf_filtered (stream,
|
||
"a variable in register %s",
|
||
gdbarch_register_name (gdbarch, regno));
|
||
return 1;
|
||
}
|
||
|
||
/* The location expression for a TLS variable looks like this (on a
|
||
64-bit LE machine):
|
||
|
||
DW_AT_location : 10 byte block: 3 4 0 0 0 0 0 0 0 e0
|
||
(DW_OP_addr: 4; DW_OP_GNU_push_tls_address)
|
||
|
||
0x3 is the encoding for DW_OP_addr, which has an operand as long
|
||
as the size of an address on the target machine (here is 8
|
||
bytes). 0xe0 is the encoding for DW_OP_GNU_push_tls_address.
|
||
The operand represents the offset at which the variable is within
|
||
the thread local storage. */
|
||
|
||
if (dlbaton->size > 1
|
||
&& dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address)
|
||
if (dlbaton->data[0] == DW_OP_addr)
|
||
{
|
||
struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu);
|
||
struct gdbarch *gdbarch = get_objfile_arch (objfile);
|
||
CORE_ADDR offset = dwarf2_read_address (gdbarch,
|
||
&dlbaton->data[1],
|
||
&dlbaton->data[dlbaton->size - 1],
|
||
addr_size);
|
||
fprintf_filtered (stream,
|
||
"a thread-local variable at offset %s in the "
|
||
"thread-local storage for `%s'",
|
||
paddress (gdbarch, offset), objfile->name);
|
||
return 1;
|
||
}
|
||
|
||
|
||
fprintf_filtered (stream,
|
||
"a variable with complex or multiple locations (DWARF2)");
|
||
return 1;
|
||
}
|
||
|
||
|
||
/* Describe the location of SYMBOL as an agent value in VALUE, generating
|
||
any necessary bytecode in AX.
|
||
|
||
NOTE drow/2003-02-26: This function is extremely minimal, because
|
||
doing it correctly is extremely complicated and there is no
|
||
publicly available stub with tracepoint support for me to test
|
||
against. When there is one this function should be revisited. */
|
||
|
||
static void
|
||
locexpr_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch,
|
||
struct agent_expr *ax, struct axs_value *value)
|
||
{
|
||
struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
|
||
dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value,
|
||
dlbaton->data, dlbaton->size);
|
||
}
|
||
|
||
/* The set of location functions used with the DWARF-2 expression
|
||
evaluator. */
|
||
const struct symbol_computed_ops dwarf2_locexpr_funcs = {
|
||
locexpr_read_variable,
|
||
locexpr_read_needs_frame,
|
||
locexpr_describe_location,
|
||
locexpr_tracepoint_var_ref
|
||
};
|
||
|
||
|
||
/* Wrapper functions for location lists. These generally find
|
||
the appropriate location expression and call something above. */
|
||
|
||
/* Return the value of SYMBOL in FRAME using the DWARF-2 expression
|
||
evaluator to calculate the location. */
|
||
static struct value *
|
||
loclist_read_variable (struct symbol *symbol, struct frame_info *frame)
|
||
{
|
||
struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
struct value *val;
|
||
gdb_byte *data;
|
||
size_t size;
|
||
|
||
data = find_location_expression (dlbaton, &size,
|
||
frame ? get_frame_address_in_block (frame)
|
||
: 0);
|
||
if (data == NULL)
|
||
{
|
||
val = allocate_value (SYMBOL_TYPE (symbol));
|
||
VALUE_LVAL (val) = not_lval;
|
||
set_value_optimized_out (val, 1);
|
||
}
|
||
else
|
||
val = dwarf2_evaluate_loc_desc (symbol, frame, data, size,
|
||
dlbaton->per_cu);
|
||
|
||
return val;
|
||
}
|
||
|
||
/* Return non-zero iff we need a frame to evaluate SYMBOL. */
|
||
static int
|
||
loclist_read_needs_frame (struct symbol *symbol)
|
||
{
|
||
/* If there's a location list, then assume we need to have a frame
|
||
to choose the appropriate location expression. With tracking of
|
||
global variables this is not necessarily true, but such tracking
|
||
is disabled in GCC at the moment until we figure out how to
|
||
represent it. */
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Print a natural-language description of SYMBOL to STREAM. */
|
||
static int
|
||
loclist_describe_location (struct symbol *symbol, struct ui_file *stream)
|
||
{
|
||
/* FIXME: Could print the entire list of locations. */
|
||
fprintf_filtered (stream, "a variable with multiple locations");
|
||
return 1;
|
||
}
|
||
|
||
/* Describe the location of SYMBOL as an agent value in VALUE, generating
|
||
any necessary bytecode in AX. */
|
||
static void
|
||
loclist_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch,
|
||
struct agent_expr *ax, struct axs_value *value)
|
||
{
|
||
struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
|
||
gdb_byte *data;
|
||
size_t size;
|
||
|
||
data = find_location_expression (dlbaton, &size, ax->scope);
|
||
if (data == NULL)
|
||
error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol));
|
||
|
||
dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value, data, size);
|
||
}
|
||
|
||
/* The set of location functions used with the DWARF-2 expression
|
||
evaluator and location lists. */
|
||
const struct symbol_computed_ops dwarf2_loclist_funcs = {
|
||
loclist_read_variable,
|
||
loclist_read_needs_frame,
|
||
loclist_describe_location,
|
||
loclist_tracepoint_var_ref
|
||
};
|