gdb/testsuite/gdb.dwarf2/symbol_needs_eval_fail.exp

# Copyright 2017-2020 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 the symbol needs check mechanism if it assumes that faking
# reads from a target is a safe thing to do.
#
# In particular, the test uses a relative branch DWARF operation to
# hide a register read. If the target reads are indeed faked, the
# result returned will be wrong.

load_lib dwarf.exp

# This test can only be run on targets which support DWARF-2 and use gas.
if {![dwarf2_support]} {
    return 0
}

# Choose suitable integer registers for the test.

set dwarf_regnum 0

if { [is_aarch64_target] } {
    set regname x0
} elseif { [is_aarch32_target]
	   || [istarget "s390*-*-*" ]
	   || [istarget "powerpc*-*-*"]
	   || [istarget "rs6000*-*-aix*"] } {
    set regname r0
} elseif { [is_x86_like_target] } {
    set regname eax
} elseif { [is_amd64_regs_target] } {
    set regname rax
} else {
    verbose "Skipping ${gdb_test_file_name}."
    return
}

standard_testfile symbol_needs_eval.c ${gdb_test_file_name}-dw.S

# Make some DWARF for the test.

set asm_file [standard_output_file $srcfile2]
Dwarf::assemble $asm_file {
    global dwarf_regnum regname

    set exec_mask_var [gdb_target_symbol exec_mask]

    cu {} {
	DW_TAG_compile_unit {
	    {DW_AT_name symbol_needs_eval.c}
	    {DW_AT_comp_dir /tmp}
	} {
	    declare_labels int_type_label

	    # define int type
	    int_type_label: DW_TAG_base_type {
		{DW_AT_name "int"}
		{DW_AT_encoding @DW_ATE_signed}
		{DW_AT_byte_size 4 DW_FORM_sdata}
	    }

	    # define artificial variable a
	    DW_TAG_variable {
		{DW_AT_name a}
		{DW_AT_type :$int_type_label}
		{DW_AT_location {
		    DW_OP_addr $exec_mask_var
		    DW_OP_deref

		    # conditional jump to DW_OP_bregx
		    DW_OP_bra 4
		    DW_OP_lit0

		    # jump to DW_OP_stack_value
		    DW_OP_skip 3
		    DW_OP_bregx $dwarf_regnum 0
		    DW_OP_stack_value
		} SPECIAL_expr}
		{external 1 flag}
	    }
	}
    }
}

if { [prepare_for_testing ${testfile}.exp ${testfile} \
     [list $srcfile $asm_file] {nodebug}] } {
    return -1
}

# The variable's location expression requires a frame,
# so an error should be reported.
gdb_test "print/d a" "No frame selected." "variable a can't be printed"

if ![runto_main] {
    return -1
}

gdb_test_no_output "set var \$$regname = 2" "init reg to 2"

gdb_test "print/d a" " = 2" "a == 2"