old-cross-binutils/gdb/testsuite/gdb.ada/n_arr_bound.exp

33 lines
1 KiB
Text
Raw Normal View History

Handling of empty Ada ranges with a negative upper bound. Consider the following variable declaration: type Array_Type is array (Integer range <>) of Integer; Var: Array_Type (0 .. -1); "ptype var" prints the wrong upper bound for that array: (gdb) ptype var type = array (0 .. 4294967295) of integer The debugging info for the type of variable "Var" is as follow: <2><cf>: Abbrev Number: 13 (DW_TAG_structure_type) <d0> DW_AT_name : foo__var___PAD <3><db>: Abbrev Number: 14 (DW_TAG_member) <dc> DW_AT_name : F <e0> DW_AT_type : <0xa5> This is just an artifact from code generation, which is just a wrapper that we should ignore. The real type is the type of field "F" in that PAD type, which is described as: <2><a5>: Abbrev Number: 10 (DW_TAG_array_type) <a6> DW_AT_name : foo__TvarS <3><b6>: Abbrev Number: 11 (DW_TAG_subrange_type) <b7> DW_AT_type : <0xc1> <bb> DW_AT_lower_bound : 0 <bc> DW_AT_upper_bound : 0xffffffff Trouble occurs because DW_AT_upper_bound is encoded using a DW_FORM_data4, which is ambiguous regarding signedness. In that case, dwarf2read.c::dwarf2_get_attr_constant_value reads the value as unsigned, which is not what we want in this case. As it happens, we already have code dealing with this situation in dwarf2read.c::read_subrange_type which checks whether the subrange's type is signed or not, and if it is, fixes the bound's value by sign-extending it: if (high.kind == PROP_CONST && !TYPE_UNSIGNED (base_type) && (high.data.const_val & negative_mask)) high.data.const_val |= negative_mask; Unfortunately, what happens in our case is that the base type of the array's subrange type is marked as being unsigned, and so we never get to apply the sign extension. Following the DWARF trail, the range's base type is described as another subrange type... <2><c1>: Abbrev Number: 12 (DW_TAG_subrange_type) <c7> DW_AT_name : foo__TTvarSP1___XDLU_0__1m <cb> DW_AT_type : <0x2d> ... whose base type is, (finally), a basic type (signed): <1><2d>: Abbrev Number: 2 (DW_TAG_base_type) <2e> DW_AT_byte_size : 4 <2f> DW_AT_encoding : 5 (signed) <30> DW_AT_name : integer The reason why GDB thinks that foo__TTvarSP1___XDLU_0__1m (the base type of the array's range type) is an unsigned type is found in gdbtypes.c::create_range_type. We consider that a range type is unsigned iff its lower bound is >= 0: if (low_bound->kind == PROP_CONST && low_bound->data.const_val >= 0) TYPE_UNSIGNED (result_type) = 1; That is normally sufficient, as one would expect the upper bound to always be greater or equal to the lower bound. But Ada actually allows the declaration of empty range types where the upper bound is less than the lower bound. In this case, the upper bound is negative, so we should not be marking the type as unsigned. This patch fixes the issue by simply checking the upper bound as well as the lower bound, and clears the range type's unsigned flag when it is found to be constant and negative. gdb/ChangeLog: * gdbtypes.c (create_range_type): Unset RESULT_TYPE's flag_unsigned if HIGH_BOUND is constant and negative. gdb/testsuite/ChangeLog: * gdb.ada/n_arr_bound: New testcase. Tested on x86_64-linux.
2014-10-02 22:17:49 +00:00
# Copyright 2014 Free Software Foundation, Inc.
#
# 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/>.
load_lib "ada.exp"
if { [skip_ada_tests] } { return -1 }
standard_ada_testfile foo
if {[gdb_compile_ada "${srcfile}" "${binfile}" executable {debug}] != ""} {
return -1
}
clean_restart ${testfile}
set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
runto "foo.adb:$bp_location"
gdb_test "ptype var" \
"= array \\(0 .. -1\\) of integer"