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

   1 # Copyright 2016-2024 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 global variable whose location is a DW_OP_addr.
  18
  19 require allow_cplus_tests
  20
  21 load_lib dwarf.exp
  22
  23 # This test can only be run on targets which support DWARF-2 and use gas.
  24 require dwarf2_support
  25
  26 # We'll place the output of Dwarf::assemble in implref-global.S.
  27 standard_testfile .c .S
  28
  29 # ${testfile} is now "implref-global".  srcfile2 is "implref-global.S".
  30 set executable ${testfile}
  31 set asm_file [standard_output_file ${srcfile2}]
  32
  33 # We need to know the size of integer and address types in order
  34 # to write some of the debugging info we'd like to generate.
  35 #
  36 # For that, we ask GDB by debugging our implref-global program.
  37 # Any program would do, but since we already have implref-global
  38 # specifically for this testcase, might as well use that.
  39 if [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] {
  40     return -1
  41 }
  42
  43 # Create the DWARF.  We need a regular variable and a reference to it that'll
  44 # be marked with DW_OP_GNU_implicit_pointer.  The variable must be global so
  45 # that its name is an exported symbol that we can reference from the DWARF
  46 # using gdb_target_symbol.
  47 Dwarf::assemble ${asm_file} {
  48     cu {} {
  49         DW_TAG_compile_unit {
  50             {DW_AT_language @DW_LANG_C_plus_plus}
  51         } {
  52             declare_labels int_label variable_label ref_label
  53             set int_size [get_sizeof "int" -1]
  54
  55             # gdb always assumes references are implemented as pointers.
  56             set addr_size [get_sizeof "void *" -1]
  57
  58             int_label: DW_TAG_base_type {
  59                 {DW_AT_byte_size ${int_size} DW_FORM_udata}
  60                 {DW_AT_encoding @DW_ATE_signed}
  61                 {DW_AT_name "int"}
  62             }
  63
  64             ref_label: DW_TAG_reference_type {
  65                 {DW_AT_byte_size ${addr_size} DW_FORM_udata}
  66                 {DW_AT_type :${int_label}}
  67             }
  68
  69             variable_label: DW_TAG_variable {
  70                 {DW_AT_name "global_var"}
  71                 {DW_AT_type :${int_label}}
  72                 {DW_AT_external 1 DW_FORM_flag}
  73                 {DW_AT_location {DW_OP_addr [gdb_target_symbol "global_var"]} SPECIAL_expr}
  74             }
  75
  76             DW_TAG_subprogram {
  77                 {MACRO_AT_func { "main" }}
  78                 {DW_AT_type :${int_label}}
  79                 {DW_AT_external 1 DW_FORM_flag}
  80             } {
  81                 DW_TAG_variable {
  82                     {DW_AT_name "ref"}
  83                     {DW_AT_type :${ref_label}}
  84                     {DW_AT_location {DW_OP_GNU_implicit_pointer ${variable_label} 0} SPECIAL_expr}
  85                 }
  86             }
  87         }
  88     }
  89 }
  90
  91 if [prepare_for_testing "failed to prepare" ${executable} [list ${asm_file} ${srcfile}] {}] {
  92     return -1
  93 }
  94
  95 # DW_OP_GNU_implicit_pointer implementation requires a valid frame.
  96 if ![runto_main] {
  97     return -1
  98 }
  99
 100 # Address of the referenced value.
 101 set address [get_hexadecimal_valueof "&global_var" ""]
 102
 103 # Doing 'print ref' should show us e.g. '(int &) @0xdeadbeef: 42'.
 104 gdb_test "print ref" " = \\(int &\\) @${address}: \\\d+"
 105
 106 # Doing 'print &ref' should show us e.g. '(int *) 0xdeadbeef <global_var>'.
 107 gdb_test "print &ref" " = \\(int \\*\\) ${address} <global_var>"
 108
 109 # gdb assumes C++ references are implemented as pointers, and print &(&ref)
 110 # shows us the underlying pointer's address.  Since in this case there's no
 111 # physical pointer, gdb should tell us so.
 112 gdb_test "print &(&ref)" "Attempt to take address of value not located in memory."
 113
 114 # Test assignment through the synthetic reference.
 115 set new_value 10
 116 gdb_test_no_output "set (ref = ${new_value})"
 117 gdb_test "print ref" " = \\(int &\\) @${address}: ${new_value}" "print ref after assignment"
 118 gdb_test "print global_var" " = ${new_value}" "print global_var after assignment"