gdb/testsuite/gdb.dwarf2/dw2-opt-structptr.exp

# Copyright 2016-2021 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# This test ensures that with "set print object on", -var-create will
# return "<optimized out>" for an optimized out pointer to structure,
# rather than attempting to dereference the pointer to determine its
# actual type (instead of its declared type).  We want to test that GDB
# can display such a pointer without throwing an error, while also
# ensuring that any attempt to dereference the pointer *will* throw an
# error.

load_lib dwarf.exp

# This test can only be run on targets which support DWARF-2 and use gas.
if {![dwarf2_support]} {
    return 0
}

standard_testfile .c -dw.S

# Generate a test program with dwarf information showing the variable
# 'ptr', a pointer-to-struct, as optimized out.  The dwarf will also
# describe the structure as have a scalar, array, and pointer-to-struct
# members.

proc build_test_program {} {
    global testfile srcfile srcfile2

    # Make some DWARF for the test.
    set asm_file [standard_output_file $srcfile2]
    Dwarf::assemble $asm_file {
	global srcfile

	# Creating a CU with 4-byte addresses lets this test link on
	# both 32- and 64-bit machines.
	cu { addr_size 4 } {
    
	    DW_TAG_compile_unit {
		{DW_AT_language @DW_LANG_C99}
		{DW_AT_name     $srcfile}
		{DW_AT_comp_dir /tmp}
	    } {
		declare_labels int_label struct_label pointer_label \
			       array_label

		int_label: DW_TAG_base_type {
		    {DW_AT_byte_size 4 DW_FORM_sdata}
		    {DW_AT_encoding  @DW_ATE_signed}
		    {DW_AT_name      integer}
		}
    
		array_label: DW_TAG_array_type {
		    {DW_AT_name foo__array_type}
		    {DW_AT_type :$int_label}
		} {
		    DW_TAG_subrange_type {
			{DW_AT_type	   :$int_label}
			{DW_AT_lower_bound 0   DW_FORM_data1}
			{DW_AT_upper_bound 127 DW_FORM_data1}
		    }   
		}
    
		struct_label: DW_TAG_structure_type {
		    {DW_AT_name "foo"}
		    {DW_AT_byte_size 12 DW_FORM_sdata}
		} {
		    member {
			{name a}
			{type :$int_label}
			{data_member_location 0 data1}
		    }
		    member {
			{name x}
			{type :$array_label}
			{data_member_location 4 data1}
		    }
		    member {
			{name y}
			{type :$pointer_label}
			{data_member_location 8 data1}
		    }
		}
    
		pointer_label: DW_TAG_pointer_type {
		    {DW_AT_byte_size 4 DW_FORM_sdata}
		    {DW_AT_type  :$struct_label}
		}
    
		DW_TAG_subprogram {
		    {DW_AT_name func01}
		    {DW_AT_type :$int_label}
		    {external   1 flag}
		    {MACRO_AT_func {func01}}
		} {
		    DW_TAG_variable {
			{DW_AT_name ptr}
			{DW_AT_type :$pointer_label}
			{DW_AT_location {} DW_FORM_block1}
		    }
		}
    
		DW_TAG_subprogram {
		    {DW_AT_name main}
		    {DW_AT_type :$int_label}
		    {external   1 flag}
		    {MACRO_AT_func {main}}
		} {
		}
	    }
	}
    }
    
    set sources "$srcfile $asm_file"
    if {[build_executable "failed to compile" $testfile $sources {nodebug}]} {
	return -1
    }
}

# Test access to an optimized-out pointer-to-struct using the
# console interpreter.

proc do_console_test {} {
    global binfile

    clean_restart $binfile

    with_test_prefix "console" {
	gdb_test_no_output "set print object on"

	if {![runto_main]} {
	    return -1
	}

	if {![runto func01]} {
	    return -1
	}
	
	gdb_test "info addr ptr" "Symbol \"ptr\" is optimized out."
	
	gdb_test "print ptr" "<optimized out>"
	
	gdb_test "print *ptr" "value has been optimized out"
	
	gdb_test "print ptr->a" "value has been optimized out"
	
	gdb_test "print ptr->x" "value has been optimized out"
	
	gdb_test "print ptr->y" "value has been optimized out"
    }
}

# Test access to an optimized-out pointer-to-struct using the
# MI interpreter.

proc do_mi_test {} {

    load_lib mi-support.exp
    set MIFLAGS "-i=mi"

    global mi_gdb_prompt
    global srcdir
    global subdir
    global binfile
    
    with_test_prefix "mi" {
	gdb_exit
	if {[mi_gdb_start]} {
	    return -1
	}
	
	mi_delete_breakpoints
	mi_gdb_reinitialize_dir $srcdir/$subdir
	mi_gdb_load $binfile
	
	# This causes GDB to dereference a pointer-to-structure when doing
	# -var-create.
	mi_gdb_test "-gdb-set print object on" ".*" "set print object on"
	
	mi_gdb_test "-break-insert main" ".*" "insert breakpoint main"
	mi_gdb_test "-break-insert func01" ".*" "insert breakpoint func01"
	
	# Run to main.  Use an explicit expect here since the limited
	# debug info will result in output that isn't handled by the
	# MI test utilities.
	set test "run to main"
	mi_run_cmd
	gdb_expect {
	    -re "\\*stopped,reason=\"breakpoint-hit\".*func=\"main\".*$mi_gdb_prompt$" {
		pass "$test"
	    }
	    timeout {
		fail "$test (timeout)"
	    }
	}
	
	# Run to func01.  Use an explicit expect here as above.
	set test "continue to func01"
	mi_send_resuming_command "exec-continue" "$test"
	gdb_expect {
	    -re "\\*stopped,reason=\"breakpoint-hit\".*func=\"func01\".*$mi_gdb_prompt$" {
		pass "$test"
	    }
	    timeout {
		fail "$test (timeout)"
	    }
	}
	
	# Test that -var-create for 'ptr' is successful.
	mi_create_varobj "var1" "ptr" "create varobj for ptr"
	
	# Test that -var-list-children of 'ptr' is successful.
	mi_list_varobj_children "var1" { \
	    {var1.a a 0 integer} \
	    {var1.x x 128 foo__array_type} \
	    {var1.y y 3 "struct foo \\*"} \
	} "get children of var1 (ptr)"

	# Test that dereferencing 'ptr' will throw an error.
	mi_gdb_test "-var-create var2 * &((ptr)->a)" \
	    "\\^error,msg=\"value has been optimized out\"" \
	    "throw error, dereference ptr to access integer member "

	# Test that dereferencing 'ptr' will throw an error.
	mi_gdb_test "-var-create var3 * &((ptr)->x)" \
	    "\\^error,msg=\"value has been optimized out\"" \
	    "throw error, dereference ptr to access array member "

	# Test that dereferencing 'ptr' will throw an error.
	mi_gdb_test "-var-create var4 * &((ptr)->y)" \
	    "\\^error,msg=\"value has been optimized out\"" \
	    "throw error, dereference ptr to access pointer member "
    }
}

if { [build_test_program] == -1 } {
    return -1
}

do_console_test
do_mi_test