2015-01-01 09:32:14 +00:00
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# Copyright 2014-2015 Free Software Foundation, Inc.
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DWARF: Add array DW_AT_bit_stride and DW_AT_byte_stride support
Consider the following declarations in Ada...
type Item is range -32 .. 31;
for Item'Size use 6;
type Table is array (Natural range 0 .. 4) of Item;
pragma Pack (Table);
... which declare a packed array whose elements are 6 bits long.
The debugger currently does not notice that the array is packed,
and thus prints values of this type incorrectly. This can be seen
in the "ptype" output:
(gdb) ptype table
type = array (0 .. 4) of foo.item
Normally, the debugger should print:
(gdb) ptype table
type = array (0 .. 4) of foo.item <packed: 6-bit elements>
The debugging information for this array looks like this:
.uleb128 0xf # (DIE (0x15c) DW_TAG_array_type)
.long .LASF9 # DW_AT_name: "pck__table"
.byte 0x6 # DW_AT_bit_stride
.long 0x1a9 # DW_AT_type
.uleb128 0x10 # (DIE (0x16a) DW_TAG_subrange_type)
.long 0x3b # DW_AT_type
.byte 0 # DW_AT_lower_bound
.byte 0x4 # DW_AT_upper_bound
.byte 0 # end of children of DIE 0x15c
The interesting part is the DW_AT_bit_stride attribute, which tells
the size of the array elements is 6 bits, rather than the normal
element type's size.
This patch adds support for this attribute by first creating
gdbtypes.c::create_array_type_with_stride, which is an enhanced
version of create_array_type taking an extra parameter as the stride.
The old create_array_type can then be re-implemented very simply
by calling the new create_array_type_with_stride.
We can then use this new function from dwarf2read, to create
arrays with or without stride.
gdb/ChangeLog:
* gdbtypes.h (create_array_type_with_stride): Add declaration.
* gdbtypes.c (create_array_type_with_stride): New function,
renaming create_array_type, but with an added parameter
called "bit_stride".
(create_array_type): Re-implement using
create_array_type_with_stride.
* dwarf2read.c (read_array_type): Add support for DW_AT_byte_stride
and DW_AT_bit_stride attributes.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/arr-stride.c: New file.
* gdb.dwarf2/arr-stride.exp: New file.
The test, relying purely on generating an assembly file, only
verifies the type description of our array. But I was also
able to verify manually that the debugger print values of these
types correctly as well (which was not the case prior to this
patch).
2014-01-29 13:39:56 +00:00
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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load_lib dwarf.exp
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# This test can only be run on targets which support DWARF-2 and use gas.
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if {![dwarf2_support]} {
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return 0
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}
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standard_testfile arr-stride.c arr-stride-dw.S
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# Make some DWARF for the test.
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set asm_file [standard_output_file $srcfile2]
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Dwarf::assemble $asm_file {
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cu {} {
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DW_TAG_compile_unit {
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{DW_AT_language @DW_LANG_Ada95}
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{DW_AT_name foo.adb}
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{DW_AT_comp_dir /tmp}
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} {
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declare_labels integer_label array_elt_label array_label \
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big_array_label
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integer_label: DW_TAG_base_type {
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{DW_AT_byte_size 4 DW_FORM_sdata}
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{DW_AT_encoding @DW_ATE_signed}
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{DW_AT_name integer}
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}
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array_elt_label: DW_TAG_subrange_type {
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{DW_AT_lower_bound 0xe0 DW_FORM_data1}
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{DW_AT_upper_bound 0x1f DW_FORM_data1}
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{DW_AT_name pck__item}
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{DW_AT_type :$integer_label}
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}
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DW_TAG_typedef {
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{DW_AT_name pck__table}
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{DW_AT_type :$array_label}
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}
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array_label: DW_TAG_array_type {
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{DW_AT_name pck__table}
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{DW_AT_bit_stride 6 DW_FORM_data1}
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{DW_AT_type :$array_elt_label}
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} {
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DW_TAG_subrange_type {
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{DW_AT_type :$integer_label}
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{DW_AT_lower_bound 0 DW_FORM_data1}
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{DW_AT_upper_bound 4 DW_FORM_data1}
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}
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}
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DW_TAG_typedef {
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{DW_AT_name pck__big_table}
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{DW_AT_type :$big_array_label}
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}
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big_array_label: DW_TAG_array_type {
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{DW_AT_name pck__big_table}
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{DW_AT_byte_stride 1 DW_FORM_data1}
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{DW_AT_type :$array_elt_label}
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} {
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DW_TAG_subrange_type {
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{DW_AT_type :$integer_label}
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{DW_AT_lower_bound 0 DW_FORM_data1}
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{DW_AT_upper_bound 4 DW_FORM_data1}
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}
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}
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}
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}
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}
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2014-03-07 11:45:49 +00:00
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if { [prepare_for_testing ${testfile}.exp ${testfile} \
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[list $srcfile $asm_file] {nodebug}] } {
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DWARF: Add array DW_AT_bit_stride and DW_AT_byte_stride support
Consider the following declarations in Ada...
type Item is range -32 .. 31;
for Item'Size use 6;
type Table is array (Natural range 0 .. 4) of Item;
pragma Pack (Table);
... which declare a packed array whose elements are 6 bits long.
The debugger currently does not notice that the array is packed,
and thus prints values of this type incorrectly. This can be seen
in the "ptype" output:
(gdb) ptype table
type = array (0 .. 4) of foo.item
Normally, the debugger should print:
(gdb) ptype table
type = array (0 .. 4) of foo.item <packed: 6-bit elements>
The debugging information for this array looks like this:
.uleb128 0xf # (DIE (0x15c) DW_TAG_array_type)
.long .LASF9 # DW_AT_name: "pck__table"
.byte 0x6 # DW_AT_bit_stride
.long 0x1a9 # DW_AT_type
.uleb128 0x10 # (DIE (0x16a) DW_TAG_subrange_type)
.long 0x3b # DW_AT_type
.byte 0 # DW_AT_lower_bound
.byte 0x4 # DW_AT_upper_bound
.byte 0 # end of children of DIE 0x15c
The interesting part is the DW_AT_bit_stride attribute, which tells
the size of the array elements is 6 bits, rather than the normal
element type's size.
This patch adds support for this attribute by first creating
gdbtypes.c::create_array_type_with_stride, which is an enhanced
version of create_array_type taking an extra parameter as the stride.
The old create_array_type can then be re-implemented very simply
by calling the new create_array_type_with_stride.
We can then use this new function from dwarf2read, to create
arrays with or without stride.
gdb/ChangeLog:
* gdbtypes.h (create_array_type_with_stride): Add declaration.
* gdbtypes.c (create_array_type_with_stride): New function,
renaming create_array_type, but with an added parameter
called "bit_stride".
(create_array_type): Re-implement using
create_array_type_with_stride.
* dwarf2read.c (read_array_type): Add support for DW_AT_byte_stride
and DW_AT_bit_stride attributes.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/arr-stride.c: New file.
* gdb.dwarf2/arr-stride.exp: New file.
The test, relying purely on generating an assembly file, only
verifies the type description of our array. But I was also
able to verify manually that the debugger print values of these
types correctly as well (which was not the case prior to this
patch).
2014-01-29 13:39:56 +00:00
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return -1
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}
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gdb_test_no_output "set language ada"
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gdb_test "ptype pck.table" \
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"type = array \\(0 \\.\\. 4\\) of pck\\.item <packed: 6-bit elements>"
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gdb_test "ptype pck.big_table" \
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"type = array \\(0 \\.\\. 4\\) of pck\\.item <packed: 8-bit elements>"
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