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