| /* DWARF 2 location expression support for GDB. |
| |
| Copyright (C) 2003, 2005, 2007, 2008, 2009, 2010 |
| Free Software Foundation, Inc. |
| |
| Contributed by Daniel Jacobowitz, MontaVista Software, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "defs.h" |
| #include "ui-out.h" |
| #include "value.h" |
| #include "frame.h" |
| #include "gdbcore.h" |
| #include "target.h" |
| #include "inferior.h" |
| #include "ax.h" |
| #include "ax-gdb.h" |
| #include "regcache.h" |
| #include "objfiles.h" |
| #include "exceptions.h" |
| #include "block.h" |
| |
| #include "dwarf2.h" |
| #include "dwarf2expr.h" |
| #include "dwarf2loc.h" |
| #include "dwarf2-frame.h" |
| |
| #include "gdb_string.h" |
| #include "gdb_assert.h" |
| |
| static void |
| dwarf_expr_frame_base_1 (struct symbol *framefunc, CORE_ADDR pc, |
| gdb_byte **start, size_t *length); |
| |
| /* A helper function for dealing with location lists. Given a |
| symbol baton (BATON) and a pc value (PC), find the appropriate |
| location expression, set *LOCEXPR_LENGTH, and return a pointer |
| to the beginning of the expression. Returns NULL on failure. |
| |
| For now, only return the first matching location expression; there |
| can be more than one in the list. */ |
| |
| static gdb_byte * |
| find_location_expression (struct dwarf2_loclist_baton *baton, |
| size_t *locexpr_length, CORE_ADDR pc) |
| { |
| CORE_ADDR low, high; |
| gdb_byte *loc_ptr, *buf_end; |
| int length; |
| struct objfile *objfile = dwarf2_per_cu_objfile (baton->per_cu); |
| struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| unsigned int addr_size = dwarf2_per_cu_addr_size (baton->per_cu); |
| CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1)); |
| /* Adjust base_address for relocatable objects. */ |
| CORE_ADDR base_offset = ANOFFSET (objfile->section_offsets, |
| SECT_OFF_TEXT (objfile)); |
| CORE_ADDR base_address = baton->base_address + base_offset; |
| |
| loc_ptr = baton->data; |
| buf_end = baton->data + baton->size; |
| |
| while (1) |
| { |
| if (buf_end - loc_ptr < 2 * addr_size) |
| error (_("find_location_expression: Corrupted DWARF expression.")); |
| |
| low = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
| loc_ptr += addr_size; |
| |
| /* A base-address-selection entry. */ |
| if (low == base_mask) |
| { |
| base_address = dwarf2_read_address (gdbarch, |
| loc_ptr, buf_end, addr_size); |
| loc_ptr += addr_size; |
| continue; |
| } |
| |
| high = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
| loc_ptr += addr_size; |
| |
| /* An end-of-list entry. */ |
| if (low == 0 && high == 0) |
| return NULL; |
| |
| /* Otherwise, a location expression entry. */ |
| low += base_address; |
| high += base_address; |
| |
| length = extract_unsigned_integer (loc_ptr, 2, byte_order); |
| loc_ptr += 2; |
| |
| if (pc >= low && pc < high) |
| { |
| *locexpr_length = length; |
| return loc_ptr; |
| } |
| |
| loc_ptr += length; |
| } |
| } |
| |
| /* This is the baton used when performing dwarf2 expression |
| evaluation. */ |
| struct dwarf_expr_baton |
| { |
| struct frame_info *frame; |
| struct objfile *objfile; |
| }; |
| |
| /* Helper functions for dwarf2_evaluate_loc_desc. */ |
| |
| /* Using the frame specified in BATON, return the value of register |
| REGNUM, treated as a pointer. */ |
| static CORE_ADDR |
| dwarf_expr_read_reg (void *baton, int dwarf_regnum) |
| { |
| struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| struct gdbarch *gdbarch = get_frame_arch (debaton->frame); |
| CORE_ADDR result; |
| int regnum; |
| |
| regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum); |
| result = address_from_register (builtin_type (gdbarch)->builtin_data_ptr, |
| regnum, debaton->frame); |
| return result; |
| } |
| |
| /* Read memory at ADDR (length LEN) into BUF. */ |
| |
| static void |
| dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
| { |
| read_memory (addr, buf, len); |
| } |
| |
| /* Using the frame specified in BATON, find the location expression |
| describing the frame base. Return a pointer to it in START and |
| its length in LENGTH. */ |
| static void |
| dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length) |
| { |
| /* FIXME: cagney/2003-03-26: This code should be using |
| get_frame_base_address(), and then implement a dwarf2 specific |
| this_base method. */ |
| struct symbol *framefunc; |
| struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| |
| /* Use block_linkage_function, which returns a real (not inlined) |
| function, instead of get_frame_function, which may return an |
| inlined function. */ |
| framefunc = block_linkage_function (get_frame_block (debaton->frame, NULL)); |
| |
| /* If we found a frame-relative symbol then it was certainly within |
| some function associated with a frame. If we can't find the frame, |
| something has gone wrong. */ |
| gdb_assert (framefunc != NULL); |
| |
| dwarf_expr_frame_base_1 (framefunc, |
| get_frame_address_in_block (debaton->frame), |
| start, length); |
| } |
| |
| static void |
| dwarf_expr_frame_base_1 (struct symbol *framefunc, CORE_ADDR pc, |
| gdb_byte **start, size_t *length) |
| { |
| if (SYMBOL_LOCATION_BATON (framefunc) == NULL) |
| *start = NULL; |
| else if (SYMBOL_COMPUTED_OPS (framefunc) == &dwarf2_loclist_funcs) |
| { |
| struct dwarf2_loclist_baton *symbaton; |
| |
| symbaton = SYMBOL_LOCATION_BATON (framefunc); |
| *start = find_location_expression (symbaton, length, pc); |
| } |
| else |
| { |
| struct dwarf2_locexpr_baton *symbaton; |
| symbaton = SYMBOL_LOCATION_BATON (framefunc); |
| if (symbaton != NULL) |
| { |
| *length = symbaton->size; |
| *start = symbaton->data; |
| } |
| else |
| *start = NULL; |
| } |
| |
| if (*start == NULL) |
| error (_("Could not find the frame base for \"%s\"."), |
| SYMBOL_NATURAL_NAME (framefunc)); |
| } |
| |
| /* Helper function for dwarf2_evaluate_loc_desc. Computes the CFA for |
| the frame in BATON. */ |
| |
| static CORE_ADDR |
| dwarf_expr_frame_cfa (void *baton) |
| { |
| struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| return dwarf2_frame_cfa (debaton->frame); |
| } |
| |
| /* Using the objfile specified in BATON, find the address for the |
| current thread's thread-local storage with offset OFFSET. */ |
| static CORE_ADDR |
| dwarf_expr_tls_address (void *baton, CORE_ADDR offset) |
| { |
| struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| |
| return target_translate_tls_address (debaton->objfile, offset); |
| } |
| |
| struct piece_closure |
| { |
| /* The number of pieces used to describe this variable. */ |
| int n_pieces; |
| |
| /* The architecture, used only for DWARF_VALUE_STACK. */ |
| struct gdbarch *arch; |
| |
| /* The pieces themselves. */ |
| struct dwarf_expr_piece *pieces; |
| }; |
| |
| /* Allocate a closure for a value formed from separately-described |
| PIECES. */ |
| |
| static struct piece_closure * |
| allocate_piece_closure (int n_pieces, struct dwarf_expr_piece *pieces, |
| struct gdbarch *arch) |
| { |
| struct piece_closure *c = XZALLOC (struct piece_closure); |
| |
| c->n_pieces = n_pieces; |
| c->arch = arch; |
| c->pieces = XCALLOC (n_pieces, struct dwarf_expr_piece); |
| |
| memcpy (c->pieces, pieces, n_pieces * sizeof (struct dwarf_expr_piece)); |
| |
| return c; |
| } |
| |
| static void |
| read_pieced_value (struct value *v) |
| { |
| int i; |
| long offset = 0; |
| gdb_byte *contents; |
| struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (v)); |
| |
| contents = value_contents_raw (v); |
| for (i = 0; i < c->n_pieces; i++) |
| { |
| struct dwarf_expr_piece *p = &c->pieces[i]; |
| switch (p->location) |
| { |
| case DWARF_VALUE_REGISTER: |
| { |
| struct gdbarch *arch = get_frame_arch (frame); |
| int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, |
| p->v.expr.value); |
| int reg_offset = 0; |
| |
| if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG |
| && p->size < register_size (arch, gdb_regnum)) |
| /* Big-endian, and we want less than full size. */ |
| reg_offset = register_size (arch, gdb_regnum) - p->size; |
| |
| get_frame_register_bytes (frame, gdb_regnum, reg_offset, p->size, |
| contents + offset); |
| } |
| break; |
| |
| case DWARF_VALUE_MEMORY: |
| if (p->v.expr.in_stack_memory) |
| read_stack (p->v.expr.value, contents + offset, p->size); |
| else |
| read_memory (p->v.expr.value, contents + offset, p->size); |
| break; |
| |
| case DWARF_VALUE_STACK: |
| { |
| gdb_byte bytes[sizeof (ULONGEST)]; |
| size_t n; |
| int addr_size = gdbarch_addr_bit (c->arch) / 8; |
| store_unsigned_integer (bytes, addr_size, |
| gdbarch_byte_order (c->arch), |
| p->v.expr.value); |
| n = p->size; |
| if (n > addr_size) |
| n = addr_size; |
| memcpy (contents + offset, bytes, n); |
| } |
| break; |
| |
| case DWARF_VALUE_LITERAL: |
| { |
| size_t n = p->size; |
| if (n > p->v.literal.length) |
| n = p->v.literal.length; |
| memcpy (contents + offset, p->v.literal.data, n); |
| } |
| break; |
| |
| default: |
| internal_error (__FILE__, __LINE__, _("invalid location type")); |
| } |
| offset += p->size; |
| } |
| } |
| |
| static void |
| write_pieced_value (struct value *to, struct value *from) |
| { |
| int i; |
| long offset = 0; |
| gdb_byte *contents; |
| struct piece_closure *c = (struct piece_closure *) value_computed_closure (to); |
| struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (to)); |
| |
| if (frame == NULL) |
| { |
| set_value_optimized_out (to, 1); |
| return; |
| } |
| |
| contents = value_contents_raw (from); |
| for (i = 0; i < c->n_pieces; i++) |
| { |
| struct dwarf_expr_piece *p = &c->pieces[i]; |
| switch (p->location) |
| { |
| case DWARF_VALUE_REGISTER: |
| { |
| struct gdbarch *arch = get_frame_arch (frame); |
| int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.expr.value); |
| int reg_offset = 0; |
| |
| if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG |
| && p->size < register_size (arch, gdb_regnum)) |
| /* Big-endian, and we want less than full size. */ |
| reg_offset = register_size (arch, gdb_regnum) - p->size; |
| |
| put_frame_register_bytes (frame, gdb_regnum, reg_offset, p->size, |
| contents + offset); |
| } |
| break; |
| case DWARF_VALUE_MEMORY: |
| write_memory (p->v.expr.value, contents + offset, p->size); |
| break; |
| default: |
| set_value_optimized_out (to, 1); |
| return; |
| } |
| offset += p->size; |
| } |
| } |
| |
| static void * |
| copy_pieced_value_closure (struct value *v) |
| { |
| struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| |
| return allocate_piece_closure (c->n_pieces, c->pieces, c->arch); |
| } |
| |
| static void |
| free_pieced_value_closure (struct value *v) |
| { |
| struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| |
| xfree (c->pieces); |
| xfree (c); |
| } |
| |
| /* Functions for accessing a variable described by DW_OP_piece. */ |
| static struct lval_funcs pieced_value_funcs = { |
| read_pieced_value, |
| write_pieced_value, |
| copy_pieced_value_closure, |
| free_pieced_value_closure |
| }; |
| |
| /* Evaluate a location description, starting at DATA and with length |
| SIZE, to find the current location of variable VAR in the context |
| of FRAME. */ |
| static struct value * |
| dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame, |
| gdb_byte *data, unsigned short size, |
| struct dwarf2_per_cu_data *per_cu) |
| { |
| struct value *retval; |
| struct dwarf_expr_baton baton; |
| struct dwarf_expr_context *ctx; |
| struct cleanup *old_chain; |
| |
| if (size == 0) |
| { |
| retval = allocate_value (SYMBOL_TYPE (var)); |
| VALUE_LVAL (retval) = not_lval; |
| set_value_optimized_out (retval, 1); |
| return retval; |
| } |
| |
| baton.frame = frame; |
| baton.objfile = dwarf2_per_cu_objfile (per_cu); |
| |
| ctx = new_dwarf_expr_context (); |
| old_chain = make_cleanup_free_dwarf_expr_context (ctx); |
| |
| ctx->gdbarch = get_objfile_arch (baton.objfile); |
| ctx->addr_size = dwarf2_per_cu_addr_size (per_cu); |
| ctx->baton = &baton; |
| ctx->read_reg = dwarf_expr_read_reg; |
| ctx->read_mem = dwarf_expr_read_mem; |
| ctx->get_frame_base = dwarf_expr_frame_base; |
| ctx->get_frame_cfa = dwarf_expr_frame_cfa; |
| ctx->get_tls_address = dwarf_expr_tls_address; |
| |
| dwarf_expr_eval (ctx, data, size); |
| if (ctx->num_pieces > 0) |
| { |
| struct piece_closure *c; |
| struct frame_id frame_id = get_frame_id (frame); |
| |
| c = allocate_piece_closure (ctx->num_pieces, ctx->pieces, ctx->gdbarch); |
| retval = allocate_computed_value (SYMBOL_TYPE (var), |
| &pieced_value_funcs, |
| c); |
| VALUE_FRAME_ID (retval) = frame_id; |
| } |
| else |
| { |
| switch (ctx->location) |
| { |
| case DWARF_VALUE_REGISTER: |
| { |
| struct gdbarch *arch = get_frame_arch (frame); |
| CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0); |
| int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_regnum); |
| retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame); |
| } |
| break; |
| |
| case DWARF_VALUE_MEMORY: |
| { |
| CORE_ADDR address = dwarf_expr_fetch (ctx, 0); |
| int in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0); |
| |
| retval = allocate_value (SYMBOL_TYPE (var)); |
| VALUE_LVAL (retval) = lval_memory; |
| set_value_lazy (retval, 1); |
| if (in_stack_memory) |
| set_value_stack (retval, 1); |
| set_value_address (retval, address); |
| } |
| break; |
| |
| case DWARF_VALUE_STACK: |
| { |
| gdb_byte bytes[sizeof (ULONGEST)]; |
| ULONGEST value = (ULONGEST) dwarf_expr_fetch (ctx, 0); |
| bfd_byte *contents; |
| size_t n = ctx->addr_size; |
| |
| store_unsigned_integer (bytes, ctx->addr_size, |
| gdbarch_byte_order (ctx->gdbarch), |
| value); |
| retval = allocate_value (SYMBOL_TYPE (var)); |
| contents = value_contents_raw (retval); |
| if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) |
| n = TYPE_LENGTH (SYMBOL_TYPE (var)); |
| memcpy (contents, bytes, n); |
| } |
| break; |
| |
| case DWARF_VALUE_LITERAL: |
| { |
| bfd_byte *contents; |
| size_t n = ctx->len; |
| |
| retval = allocate_value (SYMBOL_TYPE (var)); |
| contents = value_contents_raw (retval); |
| if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) |
| n = TYPE_LENGTH (SYMBOL_TYPE (var)); |
| memcpy (contents, ctx->data, n); |
| } |
| break; |
| |
| default: |
| internal_error (__FILE__, __LINE__, _("invalid location type")); |
| } |
| } |
| |
| set_value_initialized (retval, ctx->initialized); |
| |
| do_cleanups (old_chain); |
| |
| return retval; |
| } |
| |
| /* Helper functions and baton for dwarf2_loc_desc_needs_frame. */ |
| |
| struct needs_frame_baton |
| { |
| int needs_frame; |
| }; |
| |
| /* Reads from registers do require a frame. */ |
| static CORE_ADDR |
| needs_frame_read_reg (void *baton, int regnum) |
| { |
| struct needs_frame_baton *nf_baton = baton; |
| nf_baton->needs_frame = 1; |
| return 1; |
| } |
| |
| /* Reads from memory do not require a frame. */ |
| static void |
| needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
| { |
| memset (buf, 0, len); |
| } |
| |
| /* Frame-relative accesses do require a frame. */ |
| static void |
| needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length) |
| { |
| static gdb_byte lit0 = DW_OP_lit0; |
| struct needs_frame_baton *nf_baton = baton; |
| |
| *start = &lit0; |
| *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) |
| { |
| struct block *b; |
| struct symbol *framefunc; |
| int frame_reg = 0; |
| LONGEST frame_offset; |
| gdb_byte *buf_end; |
| gdb_byte *base_data; |
| size_t base_size; |
| LONGEST base_offset = 0; |
| |
| b = block_for_pc (ax->scope); |
| |
| if (!b) |
| error (_("No block found for address")); |
| |
| framefunc = block_linkage_function (b); |
| |
| if (!framefunc) |
| error (_("No function found for block")); |
| |
| dwarf_expr_frame_base_1 (framefunc, ax->scope, |
| &base_data, &base_size); |
| |
| if (base_data[0] >= DW_OP_breg0 |
| && base_data[0] <= DW_OP_breg31) |
| { |
| frame_reg = base_data[0] - DW_OP_breg0; |
| buf_end = read_sleb128 (base_data + 1, base_data + base_size, &base_offset); |
| if (buf_end != base_data + base_size) |
| error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."), |
| frame_reg, SYMBOL_PRINT_NAME (symbol)); |
| } |
| else |
| { |
| /* We don't know what to do with the frame base expression, |
| so we can't trace this variable; give up. */ |
| error (_("Cannot generate expression to collect symbol \"%s\"; DWARF 2 encoding not handled"), |
| SYMBOL_PRINT_NAME (symbol)); |
| } |
| |
| 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)); |
| |
| ax_reg (ax, frame_reg); |
| ax_const_l (ax, base_offset + 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 |
| }; |