| Message ID | 1479135786-31150-2-git-send-email-arnez@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On 11/14/2016 09:02 AM, Andreas Arnez wrote: > The DW_AT_data_bit_offset attribute was introduced by DWARF V4 and > allows specifying the offset of a data member within its containing > entity. But although the new attribute was intended to replace > DW_AT_bit_offset for this purpose, GDB ignores it, and thus GCC still > emits DW_AT_bit_offset instead. See also > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71669. > > This change fixes GDB's lack of support for DW_AT_data_bit_offset and > adds an appropriate test case. > > gdb/ChangeLog: > > PR gdb/12616 > * dwarf2read.c (dwarf2_add_field): Handle the DWARF V4 attribute > DW_AT_data_bit_offset. > > gdb/testsuite/ChangeLog: > > PR gdb/12616 > * gdb.dwarf2/nonvar-access.exp: New testcase. Check that GDB > respects the DW_AT_data_bit_offset attribute. > --- > gdb/dwarf2read.c | 4 ++ > gdb/testsuite/gdb.dwarf2/nonvar-access.exp | 103 +++++++++++++++++++++++++++++ > 2 files changed, 107 insertions(+) > create mode 100644 gdb/testsuite/gdb.dwarf2/nonvar-access.exp > > diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c > index 1ad6b00..558159a 100644 > --- a/gdb/dwarf2read.c > +++ b/gdb/dwarf2read.c > @@ -12584,6 +12584,10 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die, > - bit_offset - FIELD_BITSIZE (*fp))); > } > } > + attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu); > + if (attr != NULL) > + SET_FIELD_BITPOS (*fp, (FIELD_BITPOS (*fp) > + + dwarf2_get_attr_constant_value (attr, 0))); > > /* Get name of field. */ > fieldname = dwarf2_name (die, cu); > diff --git a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp > new file mode 100644 > index 0000000..21532a6 > --- /dev/null > +++ b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp > @@ -0,0 +1,103 @@ > +# Copyright 2016 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/>. > + > +# Test accessing "non-variable" variables, i.e., variables which are > +# optimized to a constant DWARF location expression and/or > +# partially/fully optimized out. > + > +load_lib dwarf.exp > + > +if {![dwarf2_support]} { return 0 } > + > +standard_testfile main.c nonvar-access-dw.S > + > +# Make some DWARF for the test. > +set asm_file [standard_output_file $srcfile2] > + > +Dwarf::assemble $asm_file { > + cu {} { > + compile_unit { > + {DW_AT_name main.c} > + } { > + declare_labels int_type_label short_type_label > + declare_labels struct_s_label > + > + int_type_label: base_type { > + {name "int"} > + {encoding @DW_ATE_signed} > + {byte_size 4 DW_FORM_sdata} > + } > + > + struct_s_label: structure_type { > + {name s} > + {byte_size 4 DW_FORM_sdata} > + } { > + member { > + {name a} > + {type :$int_type_label} > + {data_member_location 0 DW_FORM_udata} > + {bit_size 8 DW_FORM_udata} > + } > + member { > + {name b} > + {type :$int_type_label} > + {data_bit_offset 8 DW_FORM_udata} > + {bit_size 24 DW_FORM_udata} > + } > + } > + > + DW_TAG_subprogram { > + {name main} > + {DW_AT_external 1 flag} > + {low_pc [gdb_target_symbol main] DW_FORM_addr} > + {high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr} > + } { > + DW_TAG_variable { > + {name undef_int} > + {type :$int_type_label} > + } > + DW_TAG_variable { > + {name undef_s} > + {type :$struct_s_label} > + } > + DW_TAG_variable { > + {name def_s} > + {type :$struct_s_label} > + {location { > + const1u 0 > + stack_value > + bit_piece 8 0 > + const1s -1 > + stack_value > + bit_piece 24 0 > + } SPECIAL_expr} > + } > + } > + } > + } > +} > + > +if { [prepare_for_testing ${testfile}.exp ${testfile} \ > + [list $srcfile $asm_file] {nodebug}] } { > + return -1 > +} > + > +if ![runto_main] { > + return -1 > +} > + > +gdb_test "print def_s" " = \\{a = 0, b = -1\\}" > +gdb_test "print undef_int" " = <optimized out>" > +gdb_test "print undef_s.a" " = <optimized out>" > Looks good to me.
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 1ad6b00..558159a 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -12584,6 +12584,10 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die, - bit_offset - FIELD_BITSIZE (*fp))); } } + attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu); + if (attr != NULL) + SET_FIELD_BITPOS (*fp, (FIELD_BITPOS (*fp) + + dwarf2_get_attr_constant_value (attr, 0))); /* Get name of field. */ fieldname = dwarf2_name (die, cu); diff --git a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp new file mode 100644 index 0000000..21532a6 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp @@ -0,0 +1,103 @@ +# Copyright 2016 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/>. + +# Test accessing "non-variable" variables, i.e., variables which are +# optimized to a constant DWARF location expression and/or +# partially/fully optimized out. + +load_lib dwarf.exp + +if {![dwarf2_support]} { return 0 } + +standard_testfile main.c nonvar-access-dw.S + +# Make some DWARF for the test. +set asm_file [standard_output_file $srcfile2] + +Dwarf::assemble $asm_file { + cu {} { + compile_unit { + {DW_AT_name main.c} + } { + declare_labels int_type_label short_type_label + declare_labels struct_s_label + + int_type_label: base_type { + {name "int"} + {encoding @DW_ATE_signed} + {byte_size 4 DW_FORM_sdata} + } + + struct_s_label: structure_type { + {name s} + {byte_size 4 DW_FORM_sdata} + } { + member { + {name a} + {type :$int_type_label} + {data_member_location 0 DW_FORM_udata} + {bit_size 8 DW_FORM_udata} + } + member { + {name b} + {type :$int_type_label} + {data_bit_offset 8 DW_FORM_udata} + {bit_size 24 DW_FORM_udata} + } + } + + DW_TAG_subprogram { + {name main} + {DW_AT_external 1 flag} + {low_pc [gdb_target_symbol main] DW_FORM_addr} + {high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr} + } { + DW_TAG_variable { + {name undef_int} + {type :$int_type_label} + } + DW_TAG_variable { + {name undef_s} + {type :$struct_s_label} + } + DW_TAG_variable { + {name def_s} + {type :$struct_s_label} + {location { + const1u 0 + stack_value + bit_piece 8 0 + const1s -1 + stack_value + bit_piece 24 0 + } SPECIAL_expr} + } + } + } + } +} + +if { [prepare_for_testing ${testfile}.exp ${testfile} \ + [list $srcfile $asm_file] {nodebug}] } { + return -1 +} + +if ![runto_main] { + return -1 +} + +gdb_test "print def_s" " = \\{a = 0, b = -1\\}" +gdb_test "print undef_int" " = <optimized out>" +gdb_test "print undef_s.a" " = <optimized out>"