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Respect piece offset for DW_OP_bit_piece

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So far GDB ignores the piece offset of all kinds of DWARF bit
pieces (DW_OP_bit_piece) and treats such pieces as if the offset was zero.

This is fixed, and an appropriate test is added.

gdb/ChangeLog:

	* dwarf2loc.c (read_pieced_value): Respect the piece offset, as
	given by DW_OP_bit_piece.
	(write_pieced_value): Likewise.

  Andreas Arnez  <arnez@linux.vnet.ibm.com>

	* gdb.dwarf2/var-access.exp: Add test for composite location with
	nonzero piece offsets.
This commit is contained in:
Andreas Arnez
2017-06-13 15:20:31 +02:00
parent 242d31ab7c
commit 65d84b7616
3 changed files with 64 additions and 6 deletions
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25
gdb/dwarf2loc.c
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@@ -1824,11 +1824,14 @@ read_pieced_value (struct value *v)
int optim, unavail;
if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
&& p->size < reg_bits)
&& p->offset + p->size < reg_bits)
{
/* Big-endian, and we want less than full size. */
source_offset_bits += reg_bits - p->size;
source_offset_bits += reg_bits - (p->offset + p->size);
}
else
source_offset_bits += p->offset;
this_size = bits_to_bytes (source_offset_bits, this_size_bits);
buffer.reserve (this_size);
@@ -1851,6 +1854,7 @@ read_pieced_value (struct value *v)
break;
case DWARF_VALUE_MEMORY:
source_offset_bits += p->offset;
this_size = bits_to_bytes (source_offset_bits, this_size_bits);
buffer.reserve (this_size);
@@ -1871,12 +1875,15 @@ read_pieced_value (struct value *v)
= 8 * TYPE_LENGTH (value_type (p->v.value));
/* Use zeroes if piece reaches beyond stack value. */
if (p->size > stack_value_size_bits)
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)
source_offset_bits += stack_value_size_bits - p->size;
source_offset_bits += (stack_value_size_bits
- p->offset - p->size);
else
source_offset_bits += p->offset;
copy_bitwise (contents, dest_offset_bits,
value_contents_all (p->v.value),
@@ -1891,6 +1898,7 @@ read_pieced_value (struct value *v)
size_t n = this_size_bits;
/* Cut off at the end of the implicit value. */
source_offset_bits += p->offset;
if (source_offset_bits >= literal_size_bits)
break;
if (n > literal_size_bits - source_offset_bits)
@@ -1981,11 +1989,14 @@ write_pieced_value (struct value *to, struct value *from)
ULONGEST reg_bits = 8 * register_size (arch, gdb_regnum);
if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
&& p->size <= reg_bits)
&& p->offset + p->size < reg_bits)
{
/* Big-endian, and we want less than full size. */
dest_offset_bits += reg_bits - p->size;
dest_offset_bits += reg_bits - (p->offset + p->size);
}
else
dest_offset_bits += p->offset;
this_size = bits_to_bytes (dest_offset_bits, this_size_bits);
buffer.reserve (this_size);
@@ -2023,6 +2034,8 @@ write_pieced_value (struct value *to, struct value *from)
break;
case DWARF_VALUE_MEMORY:
{
dest_offset_bits += p->offset;
CORE_ADDR start_addr = p->v.mem.addr + dest_offset_bits / 8;
if (dest_offset_bits % 8 == 0 && this_size_bits % 8 == 0