/
expr.c
2408 lines (2053 loc) · 65.2 KB
/
expr.c
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/* DWARF 2 Expression Evaluator.
Copyright (C) 2001-2022 Free Software Foundation, Inc.
Contributed by Daniel Berlin (dan@dberlin.org)
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 "block.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "value.h"
#include "gdbcore.h"
#include "dwarf2.h"
#include "dwarf2/expr.h"
#include "dwarf2/loc.h"
#include "dwarf2/read.h"
#include "frame.h"
#include "gdbsupport/underlying.h"
#include "gdbarch.h"
#include "objfiles.h"
/* Cookie for gdbarch data. */
static struct gdbarch_data *dwarf_arch_cookie;
/* This holds gdbarch-specific types used by the DWARF expression
evaluator. See comments in execute_stack_op. */
struct dwarf_gdbarch_types
{
struct type *dw_types[3];
};
/* Allocate and fill in dwarf_gdbarch_types for an arch. */
static void *
dwarf_gdbarch_types_init (struct gdbarch *gdbarch)
{
struct dwarf_gdbarch_types *types
= GDBARCH_OBSTACK_ZALLOC (gdbarch, struct dwarf_gdbarch_types);
/* The types themselves are lazily initialized. */
return types;
}
/* Ensure that a FRAME is defined, throw an exception otherwise. */
static void
ensure_have_frame (frame_info *frame, const char *op_name)
{
if (frame == nullptr)
throw_error (GENERIC_ERROR,
_("%s evaluation requires a frame."), op_name);
}
/* Ensure that a PER_CU is defined and throw an exception otherwise. */
static void
ensure_have_per_cu (dwarf2_per_cu_data *per_cu, const char* op_name)
{
if (per_cu == nullptr)
throw_error (GENERIC_ERROR,
_("%s evaluation requires a compilation unit."), op_name);
}
/* Return the number of bytes overlapping a contiguous chunk of N_BITS
bits whose first bit is located at bit offset START. */
static size_t
bits_to_bytes (ULONGEST start, ULONGEST n_bits)
{
return (start % HOST_CHAR_BIT + n_bits + HOST_CHAR_BIT - 1) / HOST_CHAR_BIT;
}
/* See expr.h. */
CORE_ADDR
read_addr_from_reg (frame_info *frame, int reg)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
int regnum = dwarf_reg_to_regnum_or_error (gdbarch, reg);
return address_from_register (regnum, frame);
}
struct piece_closure
{
/* Reference count. */
int refc = 0;
/* The objfile from which this closure's expression came. */
dwarf2_per_objfile *per_objfile = nullptr;
/* The CU from which this closure's expression came. */
dwarf2_per_cu_data *per_cu = nullptr;
/* The pieces describing this variable. */
std::vector<dwarf_expr_piece> pieces;
/* Frame ID of frame to which a register value is relative, used
only by DWARF_VALUE_REGISTER. */
struct frame_id frame_id;
};
/* Allocate a closure for a value formed from separately-described
PIECES. */
static piece_closure *
allocate_piece_closure (dwarf2_per_cu_data *per_cu,
dwarf2_per_objfile *per_objfile,
std::vector<dwarf_expr_piece> &&pieces,
frame_info *frame)
{
piece_closure *c = new piece_closure;
c->refc = 1;
/* We must capture this here due to sharing of DWARF state. */
c->per_objfile = per_objfile;
c->per_cu = per_cu;
c->pieces = std::move (pieces);
if (frame == nullptr)
c->frame_id = null_frame_id;
else
c->frame_id = get_frame_id (frame);
for (dwarf_expr_piece &piece : c->pieces)
if (piece.location == DWARF_VALUE_STACK)
value_incref (piece.v.value);
return c;
}
/* Read or write a pieced value V. If FROM != NULL, operate in "write
mode": copy FROM into the pieces comprising V. If FROM == NULL,
operate in "read mode": fetch the contents of the (lazy) value V by
composing it from its pieces. If CHECK_OPTIMIZED is true, then no
reading or writing is done; instead the return value of this
function is true if any piece is optimized out. When
CHECK_OPTIMIZED is true, FROM must be nullptr. */
static bool
rw_pieced_value (value *v, value *from, bool check_optimized)
{
int i;
LONGEST offset = 0, max_offset;
gdb_byte *v_contents;
const gdb_byte *from_contents;
piece_closure *c
= (piece_closure *) value_computed_closure (v);
gdb::byte_vector buffer;
bool bits_big_endian = type_byte_order (value_type (v)) == BFD_ENDIAN_BIG;
gdb_assert (!check_optimized || from == nullptr);
if (from != nullptr)
{
from_contents = value_contents (from).data ();
v_contents = nullptr;
}
else
{
if (value_type (v) != value_enclosing_type (v))
internal_error (__FILE__, __LINE__,
_("Should not be able to create a lazy value with "
"an enclosing type"));
if (check_optimized)
v_contents = nullptr;
else
v_contents = value_contents_raw (v).data ();
from_contents = nullptr;
}
ULONGEST bits_to_skip = 8 * value_offset (v);
if (value_bitsize (v))
{
bits_to_skip += (8 * value_offset (value_parent (v))
+ value_bitpos (v));
if (from != nullptr
&& (type_byte_order (value_type (from))
== BFD_ENDIAN_BIG))
{
/* Use the least significant bits of FROM. */
max_offset = 8 * TYPE_LENGTH (value_type (from));
offset = max_offset - value_bitsize (v);
}
else
max_offset = value_bitsize (v);
}
else
max_offset = 8 * TYPE_LENGTH (value_type (v));
/* Advance to the first non-skipped piece. */
for (i = 0; i < c->pieces.size () && bits_to_skip >= c->pieces[i].size; i++)
bits_to_skip -= c->pieces[i].size;
for (; i < c->pieces.size () && offset < max_offset; i++)
{
dwarf_expr_piece *p = &c->pieces[i];
size_t this_size_bits, this_size;
this_size_bits = p->size - bits_to_skip;
if (this_size_bits > max_offset - offset)
this_size_bits = max_offset - offset;
switch (p->location)
{
case DWARF_VALUE_REGISTER:
{
frame_info *frame = frame_find_by_id (c->frame_id);
gdbarch *arch = get_frame_arch (frame);
int gdb_regnum = dwarf_reg_to_regnum_or_error (arch, p->v.regno);
ULONGEST reg_bits = 8 * register_size (arch, gdb_regnum);
int optim, unavail;
if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
&& p->offset + p->size < reg_bits)
{
/* Big-endian, and we want less than full size. */
bits_to_skip += reg_bits - (p->offset + p->size);
}
else
bits_to_skip += p->offset;
this_size = bits_to_bytes (bits_to_skip, this_size_bits);
buffer.resize (this_size);
if (from == nullptr)
{
/* Read mode. */
if (!get_frame_register_bytes (frame, gdb_regnum,
bits_to_skip / 8,
buffer, &optim, &unavail))
{
if (optim)
{
if (check_optimized)
return true;
mark_value_bits_optimized_out (v, offset,
this_size_bits);
}
if (unavail && !check_optimized)
mark_value_bits_unavailable (v, offset,
this_size_bits);
break;
}
if (!check_optimized)
copy_bitwise (v_contents, offset,
buffer.data (), bits_to_skip % 8,
this_size_bits, bits_big_endian);
}
else
{
/* Write mode. */
if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0)
{
/* Data is copied non-byte-aligned into the register.
Need some bits from original register value. */
get_frame_register_bytes (frame, gdb_regnum,
bits_to_skip / 8,
buffer, &optim, &unavail);
if (optim)
throw_error (OPTIMIZED_OUT_ERROR,
_("Can't do read-modify-write to "
"update bitfield; containing word "
"has been optimized out"));
if (unavail)
throw_error (NOT_AVAILABLE_ERROR,
_("Can't do read-modify-write to "
"update bitfield; containing word "
"is unavailable"));
}
copy_bitwise (buffer.data (), bits_to_skip % 8,
from_contents, offset,
this_size_bits, bits_big_endian);
put_frame_register_bytes (frame, gdb_regnum,
bits_to_skip / 8,
buffer);
}
}
break;
case DWARF_VALUE_MEMORY:
{
if (check_optimized)
break;
bits_to_skip += p->offset;
CORE_ADDR start_addr = p->v.mem.addr + bits_to_skip / 8;
if (bits_to_skip % 8 == 0 && this_size_bits % 8 == 0
&& offset % 8 == 0)
{
/* Everything is byte-aligned; no buffer needed. */
if (from != nullptr)
write_memory_with_notification (start_addr,
(from_contents
+ offset / 8),
this_size_bits / 8);
else
read_value_memory (v, offset,
p->v.mem.in_stack_memory,
p->v.mem.addr + bits_to_skip / 8,
v_contents + offset / 8,
this_size_bits / 8);
break;
}
this_size = bits_to_bytes (bits_to_skip, this_size_bits);
buffer.resize (this_size);
if (from == nullptr)
{
/* Read mode. */
read_value_memory (v, offset,
p->v.mem.in_stack_memory,
p->v.mem.addr + bits_to_skip / 8,
buffer.data (), this_size);
copy_bitwise (v_contents, offset,
buffer.data (), bits_to_skip % 8,
this_size_bits, bits_big_endian);
}
else
{
/* Write mode. */
if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0)
{
if (this_size <= 8)
{
/* Perform a single read for small sizes. */
read_memory (start_addr, buffer.data (),
this_size);
}
else
{
/* Only the first and last bytes can possibly have
any bits reused. */
read_memory (start_addr, buffer.data (), 1);
read_memory (start_addr + this_size - 1,
&buffer[this_size - 1], 1);
}
}
copy_bitwise (buffer.data (), bits_to_skip % 8,
from_contents, offset,
this_size_bits, bits_big_endian);
write_memory_with_notification (start_addr,
buffer.data (),
this_size);
}
}
break;
case DWARF_VALUE_STACK:
{
if (check_optimized)
break;
if (from != nullptr)
{
mark_value_bits_optimized_out (v, offset, this_size_bits);
break;
}
gdbarch *objfile_gdbarch = c->per_objfile->objfile->arch ();
ULONGEST stack_value_size_bits
= 8 * TYPE_LENGTH (value_type (p->v.value));
/* Use zeroes if piece reaches beyond stack value. */
if (p->offset + p->size > stack_value_size_bits)
break;
/* Piece is anchored at least significant bit end. */
if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG)
bits_to_skip += stack_value_size_bits - p->offset - p->size;
else
bits_to_skip += p->offset;
copy_bitwise (v_contents, offset,
value_contents_all (p->v.value).data (),
bits_to_skip,
this_size_bits, bits_big_endian);
}
break;
case DWARF_VALUE_LITERAL:
{
if (check_optimized)
break;
if (from != nullptr)
{
mark_value_bits_optimized_out (v, offset, this_size_bits);
break;
}
ULONGEST literal_size_bits = 8 * p->v.literal.length;
size_t n = this_size_bits;
/* Cut off at the end of the implicit value. */
bits_to_skip += p->offset;
if (bits_to_skip >= literal_size_bits)
break;
if (n > literal_size_bits - bits_to_skip)
n = literal_size_bits - bits_to_skip;
copy_bitwise (v_contents, offset,
p->v.literal.data, bits_to_skip,
n, bits_big_endian);
}
break;
case DWARF_VALUE_IMPLICIT_POINTER:
if (from != nullptr)
{
mark_value_bits_optimized_out (v, offset, this_size_bits);
break;
}
/* These bits show up as zeros -- but do not cause the value to
be considered optimized-out. */
break;
case DWARF_VALUE_OPTIMIZED_OUT:
if (check_optimized)
return true;
mark_value_bits_optimized_out (v, offset, this_size_bits);
break;
default:
internal_error (__FILE__, __LINE__, _("invalid location type"));
}
offset += this_size_bits;
bits_to_skip = 0;
}
return false;
}
static void
read_pieced_value (value *v)
{
rw_pieced_value (v, nullptr, false);
}
static void
write_pieced_value (value *to, value *from)
{
rw_pieced_value (to, from, false);
}
static bool
is_optimized_out_pieced_value (value *v)
{
return rw_pieced_value (v, nullptr, true);
}
/* An implementation of an lval_funcs method to see whether a value is
a synthetic pointer. */
static int
check_pieced_synthetic_pointer (const value *value, LONGEST bit_offset,
int bit_length)
{
piece_closure *c = (piece_closure *) value_computed_closure (value);
int i;
bit_offset += 8 * value_offset (value);
if (value_bitsize (value))
bit_offset += value_bitpos (value);
for (i = 0; i < c->pieces.size () && bit_length > 0; i++)
{
dwarf_expr_piece *p = &c->pieces[i];
size_t this_size_bits = p->size;
if (bit_offset > 0)
{
if (bit_offset >= this_size_bits)
{
bit_offset -= this_size_bits;
continue;
}
bit_length -= this_size_bits - bit_offset;
bit_offset = 0;
}
else
bit_length -= this_size_bits;
if (p->location != DWARF_VALUE_IMPLICIT_POINTER)
return 0;
}
return 1;
}
/* An implementation of an lval_funcs method to indirect through a
pointer. This handles the synthetic pointer case when needed. */
static value *
indirect_pieced_value (value *value)
{
piece_closure *c
= (piece_closure *) value_computed_closure (value);
int i;
dwarf_expr_piece *piece = NULL;
struct type *type = check_typedef (value_type (value));
if (type->code () != TYPE_CODE_PTR)
return NULL;
int bit_length = 8 * TYPE_LENGTH (type);
LONGEST bit_offset = 8 * value_offset (value);
if (value_bitsize (value))
bit_offset += value_bitpos (value);
for (i = 0; i < c->pieces.size () && bit_length > 0; i++)
{
dwarf_expr_piece *p = &c->pieces[i];
size_t this_size_bits = p->size;
if (bit_offset > 0)
{
if (bit_offset >= this_size_bits)
{
bit_offset -= this_size_bits;
continue;
}
bit_length -= this_size_bits - bit_offset;
bit_offset = 0;
}
else
bit_length -= this_size_bits;
if (p->location != DWARF_VALUE_IMPLICIT_POINTER)
return NULL;
if (bit_length != 0)
error (_("Invalid use of DW_OP_implicit_pointer"));
piece = p;
break;
}
gdb_assert (piece != NULL && c->per_cu != nullptr);
frame_info *frame = get_selected_frame (_("No frame selected."));
/* This is an offset requested by GDB, such as value subscripts.
However, due to how synthetic pointers are implemented, this is
always presented to us as a pointer type. This means we have to
sign-extend it manually as appropriate. Use raw
extract_signed_integer directly rather than value_as_address and
sign extend afterwards on architectures that would need it
(mostly everywhere except MIPS, which has signed addresses) as
the later would go through gdbarch_pointer_to_address and thus
return a CORE_ADDR with high bits set on architectures that
encode address spaces and other things in CORE_ADDR. */
bfd_endian byte_order = gdbarch_byte_order (get_frame_arch (frame));
LONGEST byte_offset
= extract_signed_integer (value_contents (value), byte_order);
byte_offset += piece->v.ptr.offset;
return indirect_synthetic_pointer (piece->v.ptr.die_sect_off,
byte_offset, c->per_cu,
c->per_objfile, frame, type);
}
/* Implementation of the coerce_ref method of lval_funcs for synthetic C++
references. */
static value *
coerce_pieced_ref (const value *value)
{
struct type *type = check_typedef (value_type (value));
if (value_bits_synthetic_pointer (value, value_embedded_offset (value),
TARGET_CHAR_BIT * TYPE_LENGTH (type)))
{
const piece_closure *closure
= (piece_closure *) value_computed_closure (value);
frame_info *frame
= get_selected_frame (_("No frame selected."));
/* gdb represents synthetic pointers as pieced values with a single
piece. */
gdb_assert (closure != NULL);
gdb_assert (closure->pieces.size () == 1);
return indirect_synthetic_pointer
(closure->pieces[0].v.ptr.die_sect_off,
closure->pieces[0].v.ptr.offset,
closure->per_cu, closure->per_objfile, frame, type);
}
else
{
/* Else: not a synthetic reference; do nothing. */
return NULL;
}
}
static void *
copy_pieced_value_closure (const value *v)
{
piece_closure *c = (piece_closure *) value_computed_closure (v);
++c->refc;
return c;
}
static void
free_pieced_value_closure (value *v)
{
piece_closure *c = (piece_closure *) value_computed_closure (v);
--c->refc;
if (c->refc == 0)
{
for (dwarf_expr_piece &p : c->pieces)
if (p.location == DWARF_VALUE_STACK)
value_decref (p.v.value);
delete c;
}
}
/* Functions for accessing a variable described by DW_OP_piece. */
static const struct lval_funcs pieced_value_funcs = {
read_pieced_value,
write_pieced_value,
is_optimized_out_pieced_value,
indirect_pieced_value,
coerce_pieced_ref,
check_pieced_synthetic_pointer,
copy_pieced_value_closure,
free_pieced_value_closure
};
/* Given context CTX, section offset SECT_OFF, and compilation unit
data PER_CU, execute the "variable value" operation on the DIE
found at SECT_OFF. */
static value *
sect_variable_value (sect_offset sect_off,
dwarf2_per_cu_data *per_cu,
dwarf2_per_objfile *per_objfile)
{
const char *var_name = nullptr;
struct type *die_type
= dwarf2_fetch_die_type_sect_off (sect_off, per_cu, per_objfile,
&var_name);
if (die_type == NULL)
error (_("Bad DW_OP_GNU_variable_value DIE."));
/* Note: Things still work when the following test is removed. This
test and error is here to conform to the proposed specification. */
if (die_type->code () != TYPE_CODE_INT
&& die_type->code () != TYPE_CODE_ENUM
&& die_type->code () != TYPE_CODE_RANGE
&& die_type->code () != TYPE_CODE_PTR)
error (_("Type of DW_OP_GNU_variable_value DIE must be an integer or pointer."));
if (var_name != nullptr)
{
value *result = compute_var_value (var_name);
if (result != nullptr)
return result;
}
struct type *type = lookup_pointer_type (die_type);
frame_info *frame = get_selected_frame (_("No frame selected."));
return indirect_synthetic_pointer (sect_off, 0, per_cu, per_objfile, frame,
type, true);
}
/* Return the type used for DWARF operations where the type is
unspecified in the DWARF spec. Only certain sizes are
supported. */
struct type *
dwarf_expr_context::address_type () const
{
gdbarch *arch = this->m_per_objfile->objfile->arch ();
dwarf_gdbarch_types *types
= (dwarf_gdbarch_types *) gdbarch_data (arch, dwarf_arch_cookie);
int ndx;
if (this->m_addr_size == 2)
ndx = 0;
else if (this->m_addr_size == 4)
ndx = 1;
else if (this->m_addr_size == 8)
ndx = 2;
else
error (_("Unsupported address size in DWARF expressions: %d bits"),
8 * this->m_addr_size);
if (types->dw_types[ndx] == NULL)
types->dw_types[ndx]
= arch_integer_type (arch, 8 * this->m_addr_size,
0, "<signed DWARF address type>");
return types->dw_types[ndx];
}
/* Create a new context for the expression evaluator. */
dwarf_expr_context::dwarf_expr_context (dwarf2_per_objfile *per_objfile,
int addr_size)
: m_addr_size (addr_size),
m_per_objfile (per_objfile)
{
}
/* Push VALUE onto the stack. */
void
dwarf_expr_context::push (struct value *value, bool in_stack_memory)
{
this->m_stack.emplace_back (value, in_stack_memory);
}
/* Push VALUE onto the stack. */
void
dwarf_expr_context::push_address (CORE_ADDR value, bool in_stack_memory)
{
push (value_from_ulongest (address_type (), value), in_stack_memory);
}
/* Pop the top item off of the stack. */
void
dwarf_expr_context::pop ()
{
if (this->m_stack.empty ())
error (_("dwarf expression stack underflow"));
this->m_stack.pop_back ();
}
/* Retrieve the N'th item on the stack. */
struct value *
dwarf_expr_context::fetch (int n)
{
if (this->m_stack.size () <= n)
error (_("Asked for position %d of stack, "
"stack only has %zu elements on it."),
n, this->m_stack.size ());
return this->m_stack[this->m_stack.size () - (1 + n)].value;
}
/* See expr.h. */
void
dwarf_expr_context::get_frame_base (const gdb_byte **start,
size_t * length)
{
ensure_have_frame (this->m_frame, "DW_OP_fbreg");
const block *bl = get_frame_block (this->m_frame, NULL);
if (bl == NULL)
error (_("frame address is not available."));
/* Use block_linkage_function, which returns a real (not inlined)
function, instead of get_frame_function, which may return an
inlined function. */
symbol *framefunc = block_linkage_function (bl);
/* 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);
func_get_frame_base_dwarf_block (framefunc,
get_frame_address_in_block (this->m_frame),
start, length);
}
/* See expr.h. */
struct type *
dwarf_expr_context::get_base_type (cu_offset die_cu_off)
{
if (this->m_per_cu == nullptr)
return builtin_type (this->m_per_objfile->objfile->arch ())->builtin_int;
struct type *result = dwarf2_get_die_type (die_cu_off, this->m_per_cu,
this->m_per_objfile);
if (result == nullptr)
error (_("Could not find type for operation"));
return result;
}
/* See expr.h. */
void
dwarf_expr_context::dwarf_call (cu_offset die_cu_off)
{
ensure_have_per_cu (this->m_per_cu, "DW_OP_call");
frame_info *frame = this->m_frame;
auto get_pc_from_frame = [frame] ()
{
ensure_have_frame (frame, "DW_OP_call");
return get_frame_address_in_block (frame);
};
dwarf2_locexpr_baton block
= dwarf2_fetch_die_loc_cu_off (die_cu_off, this->m_per_cu,
this->m_per_objfile, get_pc_from_frame);
/* DW_OP_call_ref is currently not supported. */
gdb_assert (block.per_cu == this->m_per_cu);
this->eval (block.data, block.size);
}
/* See expr.h. */
void
dwarf_expr_context::read_mem (gdb_byte *buf, CORE_ADDR addr,
size_t length)
{
if (length == 0)
return;
/* Prefer the passed-in memory, if it exists. */
if (this->m_addr_info != nullptr)
{
CORE_ADDR offset = addr - this->m_addr_info->addr;
if (offset < this->m_addr_info->valaddr.size ()
&& offset + length <= this->m_addr_info->valaddr.size ())
{
memcpy (buf, this->m_addr_info->valaddr.data (), length);
return;
}
}
read_memory (addr, buf, length);
}
/* See expr.h. */
void
dwarf_expr_context::push_dwarf_reg_entry_value (call_site_parameter_kind kind,
call_site_parameter_u kind_u,
int deref_size)
{
ensure_have_per_cu (this->m_per_cu, "DW_OP_entry_value");
ensure_have_frame (this->m_frame, "DW_OP_entry_value");
dwarf2_per_cu_data *caller_per_cu;
dwarf2_per_objfile *caller_per_objfile;
frame_info *caller_frame = get_prev_frame (this->m_frame);
call_site_parameter *parameter
= dwarf_expr_reg_to_entry_parameter (this->m_frame, kind, kind_u,
&caller_per_cu,
&caller_per_objfile);
const gdb_byte *data_src
= deref_size == -1 ? parameter->value : parameter->data_value;
size_t size
= deref_size == -1 ? parameter->value_size : parameter->data_value_size;
/* DEREF_SIZE size is not verified here. */
if (data_src == nullptr)
throw_error (NO_ENTRY_VALUE_ERROR,
_("Cannot resolve DW_AT_call_data_value"));
/* We are about to evaluate an expression in the context of the caller
of the current frame. This evaluation context may be different from
the current (callee's) context), so temporarily set the caller's context.
It is possible for the caller to be from a different objfile from the
callee if the call is made through a function pointer. */
scoped_restore save_frame = make_scoped_restore (&this->m_frame,
caller_frame);
scoped_restore save_per_cu = make_scoped_restore (&this->m_per_cu,
caller_per_cu);
scoped_restore save_addr_info = make_scoped_restore (&this->m_addr_info,
nullptr);
scoped_restore save_per_objfile = make_scoped_restore (&this->m_per_objfile,
caller_per_objfile);
scoped_restore save_addr_size = make_scoped_restore (&this->m_addr_size);
this->m_addr_size = this->m_per_cu->addr_size ();
this->eval (data_src, size);
}
/* See expr.h. */
value *
dwarf_expr_context::fetch_result (struct type *type, struct type *subobj_type,
LONGEST subobj_offset, bool as_lval)
{
value *retval = nullptr;
gdbarch *arch = this->m_per_objfile->objfile->arch ();
if (type == nullptr)
type = address_type ();
if (subobj_type == nullptr)
subobj_type = type;
if (this->m_pieces.size () > 0)
{
ULONGEST bit_size = 0;
for (dwarf_expr_piece &piece : this->m_pieces)
bit_size += piece.size;
/* Complain if the expression is larger than the size of the
outer type. */
if (bit_size > 8 * TYPE_LENGTH (type))
invalid_synthetic_pointer ();
piece_closure *c
= allocate_piece_closure (this->m_per_cu, this->m_per_objfile,
std::move (this->m_pieces), this->m_frame);
retval = allocate_computed_value (subobj_type,
&pieced_value_funcs, c);
set_value_offset (retval, subobj_offset);
}
else
{
/* If AS_LVAL is false, means that the implicit conversion
from a location description to value is expected. */
if (!as_lval)
this->m_location = DWARF_VALUE_STACK;
switch (this->m_location)
{
case DWARF_VALUE_REGISTER:
{
gdbarch *f_arch = get_frame_arch (this->m_frame);
int dwarf_regnum
= longest_to_int (value_as_long (this->fetch (0)));
int gdb_regnum = dwarf_reg_to_regnum_or_error (f_arch,
dwarf_regnum);
if (subobj_offset != 0)
error (_("cannot use offset on synthetic pointer to register"));
gdb_assert (this->m_frame != NULL);
retval = value_from_register (subobj_type, gdb_regnum,
this->m_frame);
if (value_optimized_out (retval))
{
/* This means the register has undefined value / was
not saved. As we're computing the location of some
variable etc. in the program, not a value for
inspecting a register ($pc, $sp, etc.), return a
generic optimized out value instead, so that we show
<optimized out> instead of <not saved>. */
value *tmp = allocate_value (subobj_type);
value_contents_copy (tmp, 0, retval, 0,
TYPE_LENGTH (subobj_type));
retval = tmp;
}
}
break;
case DWARF_VALUE_MEMORY:
{
struct type *ptr_type;
CORE_ADDR address = this->fetch_address (0);
bool in_stack_memory = this->fetch_in_stack_memory (0);
/* DW_OP_deref_size (and possibly other operations too) may
create a pointer instead of an address. Ideally, the
pointer to address conversion would be performed as part
of those operations, but the type of the object to
which the address refers is not known at the time of