Home | History | Annotate | Line # | Download | only in gdb.dwarf2 
      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"
    119