gdb/testsuite/gdb.dwarf2/implref-const.exp

   1 # Copyright 2016-2021 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
  19 if [skip_cplus_tests] {
  20     continue
  21 }
  22
  23 load_lib dwarf.exp
  24
  25 # This test can only be run on targets which support DWARF-2 and use gas.
  26 if ![dwarf2_support] {
  27     return 0
  28 }
  29
  30 # We'll place the output of Dwarf::assemble in implref-const.S.
  31 standard_testfile main.c .S
  32
  33 # ${testfile} is now "implref-const".  srcfile2 is "implref-const.S".
  34 set executable ${testfile}
  35 set 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.
  43 if [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.
  49 Dwarf::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
  97 if [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.
 102 if ![runto_main] {
 103     return -1
 104 }
 105
 106 # Doing 'print ref' should show us e.g. '(int &) <synthetic pointer>: 42'.
 107 gdb_test "print ref" " = \\(int &\\) <synthetic pointer>: \\\d+"
 108
 109 # The variable isn't located in memory, thus we can't take its address.
 110 gdb_test "print &var" "Can't take address of \"var\" which isn't an lvalue."
 111 gdb_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.
 116 gdb_test "print &(&ref)" "Attempt to take address of value not located in memory."