1# Copyright 2016-2020 Free Software Foundation, Inc. 2 3# This program is free software; you can redistribute it and/or modify 4# it under the terms of the GNU General Public License as published by 5# the Free Software Foundation; either version 3 of the License, or 6# (at your option) any later version. 7# 8# This program is distributed in the hope that it will be useful, 9# but WITHOUT ANY WARRANTY; without even the implied warranty of 10# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11# GNU General Public License for more details. 12# 13# You should have received a copy of the GNU General Public License 14# along with this program. If not, see <http://www.gnu.org/licenses/>. 15 16# Test a C++ reference marked with DW_OP_GNU_implicit_pointer. 17# The referenced value is a DW_AT_const_value. 18 19if [skip_cplus_tests] { 20 continue 21} 22 23load_lib dwarf.exp 24 25# This test can only be run on targets which support DWARF-2 and use gas. 26if ![dwarf2_support] { 27 return 0 28} 29 30# We'll place the output of Dwarf::assemble in implref-const.S. 31standard_testfile main.c .S 32 33# ${testfile} is now "implref-const". srcfile2 is "implref-const.S". 34set executable ${testfile} 35set asm_file [standard_output_file ${srcfile2}] 36 37# We need to know the size of integer and address types in order 38# to write some of the debugging info we'd like to generate. 39# 40# For that, we ask GDB by debugging our implref-const program. 41# Any program would do, but since we already have implref-const 42# specifically for this testcase, might as well use that. 43if [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] { 44 return -1 45} 46 47# Create the DWARF. We need a regular variable and a reference to it that'll 48# be marked with DW_OP_GNU_implicit_pointer. 49Dwarf::assemble ${asm_file} { 50 cu {} { 51 DW_TAG_compile_unit { 52 {DW_AT_language @DW_LANG_C_plus_plus} 53 } { 54 declare_labels int_label const_label variable_label ref_label 55 set int_size [get_sizeof "int" -1] 56 57 # gdb always assumes references are implemented as pointers. 58 set addr_size [get_sizeof "void *" -1] 59 set var_value 42 60 61 int_label: DW_TAG_base_type { 62 {DW_AT_byte_size ${int_size} DW_FORM_udata} 63 {DW_AT_encoding @DW_ATE_signed} 64 {DW_AT_name "int"} 65 } 66 67 ref_label: DW_TAG_reference_type { 68 {DW_AT_byte_size ${addr_size} DW_FORM_udata} 69 {DW_AT_type :${int_label}} 70 } 71 72 const_label: DW_TAG_const_type { 73 {DW_AT_type :${ref_label}} 74 } 75 76 DW_TAG_subprogram { 77 {MACRO_AT_func { "main" }} 78 {DW_AT_type :${int_label}} 79 {DW_AT_external 1 DW_FORM_flag} 80 } { 81 variable_label: DW_TAG_variable { 82 {DW_AT_name "var"} 83 {DW_AT_type :${int_label}} 84 {DW_AT_const_value ${var_value} DW_FORM_udata} 85 } 86 87 DW_TAG_variable { 88 {DW_AT_name "ref"} 89 {DW_AT_type :${const_label}} 90 {DW_AT_location {DW_OP_GNU_implicit_pointer ${variable_label} 0} SPECIAL_expr} 91 } 92 } 93 } 94 } 95} 96 97if [prepare_for_testing "failed to prepare" ${executable} [list ${asm_file} ${srcfile}] {}] { 98 return -1 99} 100 101# DW_OP_GNU_implicit_pointer implementation requires a valid frame. 102if ![runto_main] { 103 return -1 104} 105 106# Doing 'print ref' should show us e.g. '(int &) <synthetic pointer>: 42'. 107gdb_test "print ref" " = \\(int &\\) <synthetic pointer>: \\\d+" 108 109# The variable isn't located in memory, thus we can't take its address. 110gdb_test "print &var" "Can't take address of \"var\" which isn't an lvalue." 111gdb_test "print &ref" "Attempt to take address of value not located in memory." 112 113# gdb assumes C++ references are implemented as pointers, and print &(&ref) 114# shows us the underlying pointer's address. 115# Since in this case there's no physical pointer, gdb should tell us so. 116gdb_test "print &(&ref)" "Attempt to take address of value not located in memory." 117