From da5b30da2d1167591aa8d71b543f97bfdc2ec2a2 Mon Sep 17 00:00:00 2001 From: Andreas Arnez Date: Thu, 24 Nov 2016 17:48:03 +0100 Subject: [PATCH] Fix PR12616 - gdb does not implement DW_AT_data_bit_offset 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/ChangeLog | 6 ++ gdb/dwarf2read.c | 4 + gdb/testsuite/ChangeLog | 6 ++ gdb/testsuite/gdb.dwarf2/nonvar-access.exp | 103 +++++++++++++++++++++ 4 files changed, 119 insertions(+) create mode 100644 gdb/testsuite/gdb.dwarf2/nonvar-access.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index a2a11e2461b..22f02cccd50 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2016-11-24 Andreas Arnez + + PR gdb/12616 + * dwarf2read.c (dwarf2_add_field): Handle the DWARF V4 attribute + DW_AT_data_bit_offset. + 2016-11-23 Pedro Alves * Makefile.in (SFILES): Add common/run-time-clock.c. diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 1ad6b000277..558159aedad 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/ChangeLog b/gdb/testsuite/ChangeLog index c34b37d83b9..e9dc36f8576 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2016-11-24 Andreas Arnez + + PR gdb/12616 + * gdb.dwarf2/nonvar-access.exp: New testcase. Check that GDB + respects the DW_AT_data_bit_offset attribute. + 2016-11-22 Simon Marchi * gdb.base/default.exp: Fix output of "set language". diff --git a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp new file mode 100644 index 00000000000..21532a60f2b --- /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 . + +# 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" " = " +gdb_test "print undef_s.a" " = " -- 2.30.2