OpenE2K/binutils-gdb
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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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6
gdb/ChangeLog
View File

@ -1,3 +1,9 @@
2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
* dwarf2loc.c (read_pieced_value): Respect the piece offset, as
given by DW_OP_bit_piece.
(write_pieced_value): Likewise.
2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
* dwarf2loc.c (read_pieced_value): Move the buffer allocation and

25
gdb/dwarf2loc.c
View File

@ -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

39
gdb/testsuite/gdb.dwarf2/var-access.exp
View File

@ -228,6 +228,24 @@ Dwarf::assemble $asm_file {
piece 1
} SPECIAL_expr}
}
# One piece per bitfield, using piece offsets: 32 bits of
# an implicit value, 9 bits of a stack value, 13 bits of
# r0, and 10 bits of buf.
DW_TAG_variable {
{name "t3"}
{type :$struct_t_label}
{location {
implicit_value 0x12 0x34 0x56 0x78 0x9a
bit_piece 32 4
const2s -280
stack_value
bit_piece 9 2
regx [lindex $dwarf_regnum 0]
bit_piece 13 14
addr $buf_var
bit_piece 10 42
} SPECIAL_expr}
}
}
}
}
@ -304,3 +322,24 @@ gdb_test_no_output "set var t2.y = 2641"
gdb_test_no_output "set var t2.z = -400"
gdb_test_no_output "set var t2.x = 200"
gdb_test "print t2.x + t2.y + t2.z" " = 2441"
# Bitfield access through pieces with nonzero piece offsets.
gdb_test_no_output "set var \$[lindex $regname 0] = 0xa8000" \
"init reg for t3.y"
gdb_test_no_output "set var *(char \[2\] *) (a + 5) = { 70, 82 }" \
"init mem for t3.z"
switch $endian {
little {set val "u = -1484430527, x = -70, y = 42, z = 145"}
big {set val "u = 591751049, x = -70, y = 42, z = 101"}
}
gdb_test "print t3" " = \\{$val\\}" \
"initialized t3 from reg and mem"
gdb_test_no_output "set var t3.y = -1" \
"overwrite t3.y"
gdb_test "print/x \$[lindex $regname 0]" " = 0x7ffc000" \
"verify t3.y through reg"
gdb_test_no_output "set var t3.z = -614" \
"overwrite t3.z"
switch $endian {big {set val "0x59, 0xa2"} little {set val "0x6a, 0x56"}}
gdb_test "print/x *(char \[2\] *) (a + 5)" " = \\{$val\\}" \
"verify t3.z through mem"