TheRock/debug-tools/rocgdb/source/gdb/testsuite/gdb.dwarf2/access-past-end-reg.exp

# Copyright (C) 2026 Free Software Foundation, Inc.
# Copyright (C) 2026 Advanced Micro Devices, Inc. All rights reserved.

# 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 exercises the case where a DWARF expression leads the dwarf
# machinery to try to read past a given register's end.  This should be
# handled gracefully by GDB.

load_lib "dwarf.exp"

require dwarf2_support

# This test will store a 128 bits variable in a register too small to
# contain the entire value.  Select a suitable register which is less
# than 128 bits in size.
if { [is_amd64_regs_target] } {
    # Use RAX, a 64 bits register.
    set dwarf_regnum 0
    set regname "rax"
} else {
    verbose "Skipping ${gdb_test_file_name} for current architecture."
    unsupported "$gdb_test_file_name"
    return
}

standard_testfile main.c -dw.S
set dwarf_file [standard_output_file $srcfile2]

Dwarf::assemble $dwarf_file {
    get_func_info main

    cu {} {
	DW_TAG_compile_unit {
	    {DW_AT_language @DW_LANG_C}
	    {DW_AT_name $::srcfile}
	    {DW_AT_comp_dir /tmp}
	} {
	    declare_labels int_label foo_t_label bitfield_t_label

	    int_label: DW_TAG_base_type {
		{DW_AT_name int}
		{DW_AT_byte_size 4 DW_FORM_udata}
		{DW_AT_encoding @DW_ATE_signed}
	    }

	    foo_t_label: DW_TAG_structure_type {
		{DW_AT_name foo_t}
		{DW_AT_byte_size 16 DW_FORM_sdata}
	    } {
		DW_TAG_member {
		    {DW_AT_name a}
		    {DW_AT_data_member_location 0 DW_FORM_data1}
		    {DW_AT_type :$int_label}
		}
		DW_TAG_member {
		    {DW_AT_name b}
		    {DW_AT_data_member_location 4 DW_FORM_data1}
		    {DW_AT_type :$int_label}
		}
		DW_TAG_member {
		    {DW_AT_name c}
		    {DW_AT_data_member_location 8 DW_FORM_data1}
		    {DW_AT_type :$int_label}
		}
		DW_TAG_member {
		    {DW_AT_name d}
		    {DW_AT_data_member_location 12 DW_FORM_data1}
		    {DW_AT_type :$int_label}
		}
	    }

	    bitfield_t_label: DW_TAG_structure_type {
		{DW_AT_name bitfield_t}
		{DW_AT_byte_size 1 DW_FORM_sdata}
	    } {
		DW_TAG_member {
		    {DW_AT_name a}
		    {DW_AT_type :$int_label}
		    {DW_AT_bit_size 1 DW_FORM_sdata}
		    {DW_AT_data_bit_offset 0 DW_FORM_sdata}
		}
		DW_TAG_member {
		    {DW_AT_name b}
		    {DW_AT_type :$int_label}
		    {DW_AT_bit_size 1 DW_FORM_sdata}
		    {DW_AT_data_bit_offset 1 DW_FORM_sdata}
		}
		DW_TAG_member {
		    {DW_AT_name c}
		    {DW_AT_type :$int_label}
		    {DW_AT_bit_size 1 DW_FORM_sdata}
		    {DW_AT_data_bit_offset 2 DW_FORM_sdata}
		}
		DW_TAG_member {
		    {DW_AT_name d}
		    {DW_AT_type :$int_label}
		    {DW_AT_bit_size 1 DW_FORM_sdata}
		    {DW_AT_data_bit_offset 3 DW_FORM_sdata}
		}
		DW_TAG_member {
		    {DW_AT_name e}
		    {DW_AT_type :$int_label}
		    {DW_AT_bit_size 1 DW_FORM_sdata}
		    {DW_AT_data_bit_offset 4 DW_FORM_sdata}
		}
	    }

	    DW_TAG_subprogram {
		{DW_AT_name main}
		{DW_AT_low_pc $main_start DW_FORM_addr}
		{DW_AT_high_pc $main_end DW_FORM_addr}
		{DW_AT_type :$int_label}
	    } {
		DW_TAG_variable {
		    {DW_AT_name var_piece}
		    {DW_AT_type :$foo_t_label}
		    {DW_AT_location {
			DW_OP_regx $::dwarf_regnum
			DW_OP_piece 16
		    } SPECIAL_expr}
		}

		DW_TAG_variable {
		    {DW_AT_name var_reg}
		    {DW_AT_type :$foo_t_label}
		    {DW_AT_location {
			DW_OP_regx $::dwarf_regnum
		    } SPECIAL_expr}
		}

		DW_TAG_variable {
		    {DW_AT_name var_reg_past_the_end}
		    {DW_AT_type :$foo_t_label}
		    {DW_AT_location {
			DW_OP_regx $::dwarf_regnum
			DW_OP_constu 8
			DW_OP_LLVM_offset
		    } SPECIAL_expr}
		}

		DW_TAG_variable {
		    {DW_AT_name var_bitfield}
		    {DW_AT_type :$bitfield_t_label}
		    {DW_AT_location {
			DW_OP_regx $::dwarf_regnum
			DW_OP_constu 62
			DW_OP_LLVM_bit_offset
		    } SPECIAL_expr}
		}
	    }
	}
    }
}

if { [prepare_for_testing "failed to prepare" $testfile \
	[list $srcfile $dwarf_file] {nodebug}] } {
    return
}

if { ![runto_main] } {
    return
}

# The test assumes a register size of 64 bits, ensure we have this.
set regsize [get_sizeof "\$$regname" ""]
gdb_assert {$regsize == 8} "ensure register size"
gdb_test "p/x var_piece" "= {a = $::hex, b = $::hex, c = <optimized out>, d = <optimized out>}"

# Read a variable larger than the register holding it, with a simple register
# location description.
gdb_test "p/x var_reg" "= {a = $::hex, b = $::hex, c = <optimized out>, d = <optimized out>}"

# Read a value fully past the end of the register.
gdb_test "p/x var_reg_past_the_end" "= <optimized out>"

# Read a 1-byte value 2 bits away from the end of the register.  GDB needs
# to be able to read less than one byte (2 bits), bits 2-7 are optimized out.
gdb_test "p/x var_bitfield" "= {a = $::hex, b = $::hex, c = <optimized out>, d = <optimized out>, e = <optimized out>}"