Re: [PATCH 1/9] Add test for modifiable DWARF locations

Andreas Arnez
2017-04-13T11:46:50Z

On Thu, Apr 13 2017, Yao Qi wrote:

> Andreas Arnez <arnez@linux.vnet.ibm.com> writes:
>
>> This adds a test for read/write access to variables with various types of
>> DWARF locations. It uses register- and memory locations and composite
>> locations with register- and memory pieces.
>
> The last line should be put into the introduction comment of
> gdb.dwarf2/var-access.exp.

OK.

[...]

>> +# Make some DWARF for the test.
>> +
>> +set asm_file [standard_output_file $srcfile2]
>> +Dwarf::assemble $asm_file {
>> + global srcdir subdir srcfile
>> + global dwarf_regnum regname
>> +
>> + set main_func \
>> + [function_range main [list ${srcdir}/${subdir}/$srcfile]]
>
>> +
>> + DW_TAG_subprogram {
>> + {name "main"}
>> + {DW_AT_external 1 flag}
>> + {low_pc [lindex $main_func 0] DW_FORM_addr}
>> + {high_pc [lindex $main_func 1] DW_FORM_udata}
>
> You can use MACRO_AT_func, it can replace name, low_pc and high_pc.
> Also, you don't need to call function_range above.

Right, I missed that, thanks.

>
>> + } {
>> + # Simple memory location.
>> + DW_TAG_variable {
>> + {name "a"}
>> + {type :$array_a8_label}
>> + {location {
>> + addr $buf_var
>> + } SPECIAL_expr}
>> + }
>> + # Memory pieces.
>
> Nit: we can also describe where are these pieces in comments, like
>
> # Memory pieces, two bytes from &buf[0], and two
> # bytes from &buf[2].

The other way around ;-)

>
>> + DW_TAG_variable {
>> + {name "s1"}
>> + {type :$struct_s_label}
>> + {location {
>> + addr $buf_var
>> + plus_uconst 2
>> + piece 2
>> + addr $buf_var
>> + piece 2
>> + } SPECIAL_expr}
>> + }
>> + # Register- and memory pieces.
>
> Likewise.
>
> OK with the changes.

Thanks, updated the patch with the delta patch below. Also updated the
follow-on patches with similar comments for the composite locations in
var-access.exp.

--
Andreas

diff --git a/gdb/testsuite/gdb.dwarf2/var-access.exp b/gdb/testsuite/gdb.dwarf2/var-access.exp
index ee93b93..4d6c9ca 100644
--- a/gdb/testsuite/gdb.dwarf2/var-access.exp
+++ b/gdb/testsuite/gdb.dwarf2/var-access.exp
@@ -13,7 +13,9 @@
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

-# Test reading/writing variables with non-trivial DWARF locations.
+# Test reading/writing variables with non-trivial DWARF locations. In
+# particular the test uses register- and memory locations as well as
+# composite locations with register- and memory pieces.

load_lib dwarf.exp

@@ -51,8 +53,6 @@ Dwarf::assemble $asm_file {
global srcdir subdir srcfile
global dwarf_regnum regname

- set main_func \
- [function_range main [list ${srcdir}/${subdir}/$srcfile]]
set buf_var [gdb_target_symbol buf]

cu {} {
@@ -112,10 +112,8 @@ Dwarf::assemble $asm_file {
}

DW_TAG_subprogram {
- {name "main"}
+ {MACRO_AT_func { main ${srcdir}/${subdir}/${srcfile} }}
{DW_AT_external 1 flag}
- {low_pc [lindex $main_func 0] DW_FORM_addr}
- {high_pc [lindex $main_func 1] DW_FORM_udata}
} {
# Simple memory location.
DW_TAG_variable {
@@ -125,7 +123,8 @@ Dwarf::assemble $asm_file {
addr $buf_var
} SPECIAL_expr}
}
- # Memory pieces.
+ # Memory pieces: two bytes from &buf[2], and two bytes
+ # from &buf[0].
DW_TAG_variable {
{name "s1"}
{type :$struct_s_label}
@@ -137,7 +136,8 @@ Dwarf::assemble $asm_file {
piece 2
} SPECIAL_expr}
}
- # Register- and memory pieces.
+ # Register- and memory pieces: one byte each from r0,
+ # &buf[4], r1, and &buf[5].
DW_TAG_variable {
{name "s2"}
{type :$struct_s_label}