gdb/testsuite: rewrite gdb.cp/call-method-register.exp with dwarf assembler

Convert the gdb.cp/call-method-register.exp test to make use of the
DWARF assembler.

The existing gdb.cp/call-method-register.exp test relies on a GCC
extension - forcing a local variable into a particular named register.

This means that the test will only work with Clang, and, as we have to
name the register into which the variable will be placed, will only
work for those targets where we've selected a suitable register,
currently this is x86-64, i386, and ppc64.

By switching to the DWARF assembler, the test will work with gcc and
clang, and should work on most, if not all, architectures.

The test creates a small structure, something that can fit within a
register, and then tries to call a method on the structure from within
GDB.  This should fail because GDB can't take the address of the in
register structure (for the `this` pointer).

As the test is for a failure case, then we don't really care _which_
register the structure is in, and I take advantage of this for the
DWARF assembler test, I just declare that the variable is in
DW_OP_reg0, whatever that might be.  I've tested the new test on
x86-64, ppc, aarch64, and risc-v, and the test runs, and passes on all
these architectures, which is already more than we used to cover.

Additionally, on x86-64, I've tested with Clang and gcc, and the test
runs and passed with both compilers.

Reviewed-By: Lancelot SIX <lancelot.six@amd.com>
This commit is contained in:
Andrew Burgess 2022-10-27 08:59:38 +01:00
parent e86741b65b
commit f9f88aede3
2 changed files with 81 additions and 77 deletions

View File

@ -1,6 +1,6 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 1993-2022 Free Software Foundation, Inc.
Copyright 2022 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
@ -15,54 +15,9 @@
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#if defined __x86_64__
# define ASM_REG "rax"
#elif defined __i386__
# define ASM_REG "eax"
#elif defined __powerpc64__
# define ASM_REG "r9"
#else
# error "port me"
#endif
/* A class small enough that it fits in a register. */
struct small
{
int x;
int method ();
};
int
small::method ()
{
return x + 5;
}
int
register_class ()
{
/* Given the use of the GNU register-asm local variables extension,
the compiler puts this variable in a register. This means that
GDB can't call any methods for this variable, which is what we
want to test. */
register small v asm (ASM_REG);
int i;
/* Perform a computation sufficiently complicated that optimizing
compilers won't optimize out the variable. If some compiler
constant-folds this whole loop, maybe using a parameter to this
function here would help. */
v.x = 0;
for (i = 0; i < 13; ++i)
v.x += i;
--v.x; /* v.x is now 77 */
return v.x + 5; /* set breakpoint here */
}
int
main ()
{
register_class ();
asm ("main_label: .globl main_label");
return 0;
}

View File

@ -19,43 +19,92 @@
if { [skip_cplus_tests] } { continue }
load_lib "cp-support.exp"
load_lib dwarf.exp
standard_testfile .cc
standard_testfile .cc -dw.S
if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
{debug c++}]} {
return -1
}
if {![test_compiler_info gcc-*-* c++]} {
untested "test relies on a gcc extension"
return
}
set asm_file [standard_output_file $srcfile2]
Dwarf::assemble $asm_file {
proc test_call_register_class {} {
global gdb_prompt
set main_result \
[function_range main ${::srcdir}/${::subdir}/${::srcfile}]
set main_start [lindex $main_result 0]
set main_length [lindex $main_result 1]
if ![runto_main] {
return
cu {} {
compile_unit {
{DW_AT_language @DW_LANG_C_plus_plus}
{DW_AT_name $::srcfile}
{DW_AT_comp_dir /tmp}
} {
declare_labels int_type_label struct_type_label \
struct_ptr_type_label
set ptr_size [get_sizeof "void *" 96]
DW_TAG_subprogram {
{name main}
{low_pc $main_start addr}
{high_pc $main_length data8}
{DW_AT_type :$int_type_label}
}
int_type_label: DW_TAG_base_type {
{DW_AT_byte_size 4 DW_FORM_sdata}
{DW_AT_encoding @DW_ATE_signed}
{DW_AT_name int}
}
struct_type_label: DW_TAG_structure_type {
{DW_AT_byte_size 4 DW_FORM_sdata}
{DW_AT_name small}
} {
member {
{name xxx}
{type :$int_type_label}
{data_member_location 0 data1}
}
subprogram {
{name yyy}
{type :$int_type_label}
} {
formal_parameter {
{type :$struct_ptr_type_label}
{artificial 1 flag_present}
}
}
}
struct_ptr_type_label: DW_TAG_pointer_type {
{DW_AT_byte_size $ptr_size DW_FORM_data1}
{type :$struct_type_label}
}
DW_TAG_variable {
{DW_AT_name global_var}
{DW_AT_type :$struct_type_label}
{DW_AT_location {
DW_OP_reg0
} SPECIAL_expr}
{external 1 flag}
}
}
}
set bp_location [gdb_get_line_number "set breakpoint here"]
gdb_breakpoint $bp_location
gdb_continue_to_breakpoint "break here"
# This class is so small that an instance of it can fit in a register.
# When gdb tries to call a method, it gets embarrassed about taking
# the address of a register.
#
# That message is a PASS, not an XFAIL, because gdb prints an
# informative message and declines to do something impossible.
#
# The method call actually succeeds if the compiler allocates very
# small classes in memory instead of registers. If that happens,
# it's a FAIL, because the testcase is written in a form such that
# it should not happen.
gdb_test "print v.method ()" \
"Address requested for identifier \"v\" which is in register .*" \
"call method on register local"
}
test_call_register_class
if { [prepare_for_testing "failed to prepare" ${testfile} \
[list $srcfile $asm_file] {nodebug}] } {
return -1
}
if ![runto_main] {
return -1
}
gdb_test "print global_var.yyy ()" \
"Address requested for identifier \"global_var\" which is in register .*" \
"call method on register local"