/* 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'",
paddr_nz (offset), objfile->name);
return 1;
}
fprintf_filtered (stream,
"a variable with complex or multiple locations (DWARF2)");
return 1;
}
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;
}
}
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;
baton.needs_frame = 0;
ctx = new_dwarf_expr_context ();
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_tls_address = needs_frame_tls_address;
dwarf_expr_eval (ctx, data, size);
in_reg = ctx->in_reg;
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].in_reg)
in_reg = 1;
}
free_dwarf_expr_context (ctx);
return baton.needs_frame || in_reg;
}
/* 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;
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 ();
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_tls_address = dwarf_expr_tls_address;
dwarf_expr_eval (ctx, data, size);
if (ctx->num_pieces > 0)
{
int i;
long offset = 0;
bfd_byte *contents;
retval = allocate_value (SYMBOL_TYPE (var));
contents = value_contents_raw (retval);
for (i = 0; i < ctx->num_pieces; i++)
{
struct dwarf_expr_piece *p = &ctx->pieces[i];
if (p->in_reg)
{
struct gdbarch *arch = get_frame_arch (frame);
bfd_byte regval[MAX_REGISTER_SIZE];
int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->value);
get_frame_register (frame, gdb_regnum, regval);
memcpy (contents + offset, regval, p->size);
}
else /* In memory? */
{
read_memory (p->value, contents + offset, p->size);
}
offset += p->size;
}
}
else if (ctx->in_reg)
{
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);
}
else
{
CORE_ADDR address = dwarf_expr_fetch (ctx, 0);
retval = allocate_value (SYMBOL_TYPE (var));
VALUE_LVAL (retval) = lval_memory;
set_value_lazy (retval, 1);
set_value_address (retval, address);
}
set_value_initialized (retval, ctx->initialized);
free_dwarf_expr_context (ctx);
return retval;
}
