--- /dev/null
+# Copyright 2021 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/>.
+
+# This test case uses the DWARF assembler to reproduce the problem
+# described by PR28030. The bug turned out to be that
+# FIELD_LOC_KIND_DWARF_BLOCK was not handled when recursively copying
+# a value's type when preserving the value history during the freeing
+# up of objfiles associated with a shared object. (Yes, figuring out
+# how to make this happen in a concise test case turned out to be
+# challenging.)
+#
+# The following elements proved to be necessary for reproducing the
+# problem:
+#
+# 1) A location expression needed to be used with
+# DW_AT_data_member_location rather than a simple offset.
+# Moreover, this location expression needed to use opcodes
+# which GDB's DWARF reader could not convert to a simple
+# offset. (Note, however, that GDB could probably be improved
+# to handle the opcodes chosen for this test; if decode_locdesc()
+# in dwarf2/read.c is ever updated to handle both DW_OP_pick and
+# DW_OP_drop, then this test could end up passing even if
+# the bug it's intended to test has not been fixed.)
+#
+# 2) The debug info containing the above DWARF info needed
+# to be associated with a shared object since the problem
+# occurred while GDB was preserving values during the
+# purging of shared objects.
+#
+# 3) After performing some simple gdb commands, the program is
+# run again. In the course of running the objfile destructor
+# associated with the shared object, values are preserved
+# along with their types. As noted earlier, it was during
+# the recursive type copy that the bug was observed.
+#
+# Therefore, due to #2 above, this test case creates debug info
+# which is then used by a shared object.
+
+# This test can't be run on targets lacking shared library support.
+if [skip_shlib_tests] {
+ return 0
+}
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if ![dwarf2_support] {
+ return 0
+}
+
+# gdb_test_file_name is the name of this file without the .exp
+# extension. Use it to form basenames for the main program
+# and shared object.
+set main_basename ${::gdb_test_file_name}-main
+set lib_basename ${::gdb_test_file_name}-lib
+
+# We're generating DWARF assembly for the shared object; therefore,
+# the source file for the library / shared object must be listed first
+# (in the standard_testfile invocation) since ${srcfile} is used by
+# get_func_info (for determining the start, end, and length of a
+# function).
+#
+# The output of Dwarf::assemble will be placed in $lib_basename.S
+# which will be ${srcfile3} after the execution of standard_testfile.
+
+standard_testfile $lib_basename.c $main_basename.c $lib_basename.S
+
+set libsrc "${::srcdir}/${::subdir}/${::srcfile}"
+set lib_so [standard_output_file ${lib_basename}.so]
+set asm_file [standard_output_file ${::srcfile3}]
+
+# We need to know the size of some types in order to write some of the
+# debugging info that we're about to generate. For that, we ask GDB
+# by debugging the shared object associated with this test case.
+
+# Compile the shared library: -DIS_SHAREDLIB prevents main() from
+# being defined. Note that debugging symbols will be present for
+# this compilation.
+if {[gdb_compile_shlib $libsrc $lib_so \
+ {additional_flags=-DIS_SHAREDLIB debug}] != ""} {
+ untested "failed to compile shared library"
+ return
+}
+
+# Start a fresh GDB and load the shared library.
+clean_restart $lib_so
+
+# Using our running GDB session, determine sizes of several types.
+set long_size [get_sizeof "long" -1]
+set addr_size [get_sizeof "void *" -1]
+set struct_A_size [get_sizeof "g_A" -1]
+set struct_B_size [get_sizeof "g_B" -1]
+
+if { $long_size == -1 || $addr_size == -1 \
+ || $struct_A_size == -1 || $struct_B_size == -1} {
+ perror "Can't determine type sizes"
+ return
+}
+
+# Retrieve struct offset of MBR in struct TP
+proc get_offsetof { tp mbr } {
+ return [get_integer_valueof "&((${tp} *) 0)->${mbr}" -1]
+}
+
+# Use running GDB session to get struct offsets
+set A_a [get_offsetof A a]
+set A_x [get_offsetof A x]
+set B_a [get_offsetof B a]
+set B_b [get_offsetof B b]
+set B_x2 [get_offsetof B x2]
+
+# Create the DWARF.
+Dwarf::assemble ${asm_file} {
+ declare_labels L
+
+ # Find start, end, and length of functions foo and bar.
+ # These calls to get_func_info will create and set variables
+ # foo_start, bar_start, foo_end, bar_end, foo_len, and
+ # bar_len.
+ #
+ # In order to get the right answers, get_func_info (and,
+ # underneath, function_range) should use the same compiler flags
+ # as those used to make a shared object. For any targets that get
+ # this far, -fpic is probably correct.
+ #
+ # Also, it should be noted that IS_SHAREDLIB is NOT defined as one
+ # of the additional flags. Not defining IS_SHAREDLIB will cause a
+ # main() to be defined for the compilation of the shared library
+ # source file which happens as a result of using get_func_info;
+ # this is currently required in order to this facility.
+ set flags {additional_flags=-fpic debug}
+ get_func_info foo $flags
+ get_func_info bar $flags
+
+ cu {} {
+ DW_TAG_compile_unit {
+ {DW_AT_language @DW_LANG_C_plus_plus}
+ {name ${::srcfile}}
+ {stmt_list $L DW_FORM_sec_offset}
+ } {
+ declare_labels int_label class_A_label class_B_label \
+ B_ptr_label
+
+ int_label: DW_TAG_base_type {
+ {DW_AT_byte_size ${::long_size} DW_FORM_udata}
+ {DW_AT_encoding @DW_ATE_signed}
+ {DW_AT_name "int"}
+ }
+
+ class_A_label: DW_TAG_class_type {
+ {DW_AT_name "A"}
+ {DW_AT_byte_size ${::struct_A_size} DW_FORM_sdata}
+ } {
+ DW_TAG_member {
+ {DW_AT_name "a"}
+ {DW_AT_type :$int_label}
+ {DW_AT_data_member_location ${::A_a} DW_FORM_udata}
+ }
+ DW_TAG_member {
+ {DW_AT_name "x"}
+ {DW_AT_type :$int_label}
+ {DW_AT_data_member_location ${::A_x} DW_FORM_udata}
+ }
+ }
+
+ class_B_label: DW_TAG_class_type {
+ {DW_AT_name "B"}
+ {DW_AT_byte_size ${::struct_B_size} DW_FORM_sdata}
+ } {
+ # While there are easier / better ways to specify an
+ # offset used by DW_AT_data_member_location than that
+ # used below, we need a location expression here in
+ # order to reproduce the bug. Moreover, this location
+ # expression needs to use opcodes that aren't handled
+ # by decode_locdesc() in dwarf2/read.c; if we use
+ # opcodes that _are_ handled by that function, the
+ # location expression will be converted into a simple
+ # offset - which will then (again) not reproduce the
+ # bug. At the time that this test was written,
+ # neither DW_OP_pick nor DW_OP_drop were being handled
+ # by decode_locdesc(); this is why those opcodes were
+ # chosen.
+ DW_TAG_inheritance {
+ {DW_AT_type :$class_A_label}
+ {DW_AT_data_member_location {
+ DW_OP_constu ${::B_a}
+ DW_OP_plus
+ DW_OP_pick 0
+ DW_OP_drop} SPECIAL_expr}
+ {DW_AT_accessibility 1 DW_FORM_data1}
+ }
+ DW_TAG_member {
+ {DW_AT_name "b"}
+ {DW_AT_type :$int_label}
+ {DW_AT_data_member_location ${::B_b} DW_FORM_udata}
+ }
+ DW_TAG_member {
+ {DW_AT_name "x2"}
+ {DW_AT_type :$int_label}
+ {DW_AT_data_member_location ${::B_x2} DW_FORM_udata}
+ }
+ }
+
+ B_ptr_label: DW_TAG_pointer_type {
+ {DW_AT_type :$class_B_label}
+ {DW_AT_byte_size ${::addr_size} DW_FORM_sdata}
+ }
+
+ DW_TAG_variable {
+ {DW_AT_name "g_A"}
+ {DW_AT_type :$class_A_label}
+ {DW_AT_external 1 flag}
+ {DW_AT_location {DW_OP_addr [gdb_target_symbol "g_A"]} \
+ SPECIAL_expr}
+ }
+
+ DW_TAG_variable {
+ {DW_AT_name "g_B"}
+ {DW_AT_type :$class_B_label}
+ {DW_AT_external 1 flag}
+ {DW_AT_location {DW_OP_addr [gdb_target_symbol "g_B"]} \
+ SPECIAL_expr}
+ }
+
+ # We can't use MACRO_AT for the definitions of foo and bar
+ # because it doesn't provide a way to pass the appropriate
+ # flags. Therefore, we list the name, low_pc, and high_pc
+ # explicitly.
+ DW_TAG_subprogram {
+ {DW_AT_name foo}
+ {DW_AT_low_pc $foo_start DW_FORM_addr}
+ {DW_AT_high_pc $foo_end DW_FORM_addr}
+ {DW_AT_type :${B_ptr_label}}
+ {DW_AT_external 1 flag}
+ }
+
+ DW_TAG_subprogram {
+ {DW_AT_name bar}
+ {DW_AT_low_pc $bar_start DW_FORM_addr}
+ {DW_AT_high_pc $bar_end DW_FORM_addr}
+ {DW_AT_type :${B_ptr_label}}
+ {DW_AT_external 1 flag}
+ } {
+ DW_TAG_formal_parameter {
+ {DW_AT_name v}
+ {DW_AT_type :${B_ptr_label}}
+ }
+ }
+ }
+ }
+
+ lines {version 2} L {
+ include_dir "${::srcdir}/${::subdir}"
+ file_name "${::srcfile}" 1
+
+ # Generate a line table program.
+ program {
+ {DW_LNE_set_address $foo_start}
+ {line [gdb_get_line_number "foo prologue"]}
+ {DW_LNS_copy}
+ {DW_LNE_set_address foo_label}
+ {line [gdb_get_line_number "foo return"]}
+ {DW_LNS_copy}
+ {line [gdb_get_line_number "foo end"]}
+ {DW_LNS_copy}
+ {DW_LNE_set_address $foo_end}
+ {DW_LNS_advance_line 1}
+ {DW_LNS_copy}
+ {DW_LNE_end_sequence}
+
+ {DW_LNE_set_address $bar_start}
+ {line [gdb_get_line_number "bar prologue"]}
+ {DW_LNS_copy}
+ {DW_LNE_set_address bar_label}
+ {line [gdb_get_line_number "bar return"]}
+ {DW_LNS_copy}
+ {line [gdb_get_line_number "bar end"]}
+ {DW_LNS_copy}
+ {DW_LNE_set_address $bar_end}
+ {DW_LNS_advance_line 1}
+ {DW_LNS_copy}
+ {DW_LNE_end_sequence}
+ }
+ }
+}
+
+# Compile the shared object again, but this time include / use the
+# DWARF info that we've created above. Note that (again)
+# -DIS_SHAREDLIB is used to prevent inclusion of main() in the shared
+# object. Also note the use of the "nodebug" option. Any debugging
+# information that we need will be provided by the DWARF info created
+# above.
+if {[gdb_compile_shlib [list $libsrc $asm_file] $lib_so \
+ {additional_flags=-DIS_SHAREDLIB nodebug}] != ""} {
+ untested "failed to compile shared library"
+ return
+}
+
+# Compile the main program for use with the shared object.
+if [prepare_for_testing "failed to prepare" ${testfile} \
+ ${::srcfile2} [list debug shlib=$lib_so]] {
+ return -1
+}
+
+# Do whatever is necessary to make sure that the shared library is
+# loaded for remote targets.
+gdb_load_shlib ${lib_so}
+
+if ![runto_main] then {
+ fail "can't run to main"
+ return
+}
+
+# Step into foo so that we can finish out of it.
+gdb_test "step" "foo .. at .* foo end.*" "step into foo"
+
+# Finishing out of foo will create a value that will later need to
+# be preserved when restarting the program.
+gdb_test "finish" "= \\(class B \\*\\) ${::hex} .*" "finish out of foo"
+
+# Dereferencing and printing the return value isn't necessary
+# for reproducing the bug, but we should make sure that the
+# return value is what we expect it to be.
+gdb_test "p *$" { = {<A> = {a = 8, x = 9}, b = 10, x2 = 11}} \
+ "dereference return value"
+
+# The original PR28030 reproducer stepped back into the shared object,
+# so we'll do the same here:
+gdb_test "step" "bar \\(.*" "step into bar"
+
+# We don't want a clean restart here since that will be too clean.
+# The original reproducer for PR28030 set a breakpoint in the shared
+# library and then restarted via "run". The command below does roughly
+# the same thing. It's at this step that an internal error would
+# occur for PR28030. The "message" argument tells runto to turn on
+# the printing of PASSes while runto is doing its job.
+runto "bar" message
projects / binutils-gdb.git / commitdiff