binutils-gdb/gdb/testsuite/gdb.base/retval-large-struct.exp
Luis Machado bab22d0640 [aarch64/arm] Properly extract the return value returned in memory
When running gdb.cp/non-trivial-retval.exp, the following shows up for
both aarch64-linux and armhf-linux:

Breakpoint 3, f1 (i1=23, i2=100) at src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:35
35        A a;
(gdb) finish
Run till exit from #0  f1 (i1=23, i2=100) at src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:35
main () at /src/gdb/testsuite/gdb.cp/non-trivial-retval.cc:163
163       B b = f2 (i1, i2);
Value returned is $6 = {a = -11952}
(gdb)

The return value should be {a = 123} instead. This happens because the
backends don't extract the return value from the correct location. GDB should
fetch a pointer to the memory location from X8 for aarch64 and r0 for armhf.

With the patch, gdb.cp/non-trivial-retval.exp has full passes on
aarch64-linux and armhf-linux on Ubuntu 20.04/18.04.

The problem only shows up with the "finish" command. The "call" command
works correctly and displays the correct return value.

This is also related to PR gdb/28681
(https://sourceware.org/bugzilla/show_bug.cgi?id=28681) and fixes FAIL's in
gdb.ada/mi_var_array.exp.

A new testcase is provided, and it exercises GDB's ability to "finish" a
function that returns a large struct (> 16 bytes) and display the
contents of this struct correctly. This has always been incorrect for
these backends, but no testcase exercised this particular scenario.
2022-03-14 10:38:32 +00:00

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# 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
# 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 file is part of the gdb testsuite
#
# Test if "finish" behaves correctly when a function returns a
# large (> 16 bytes) struct.
standard_testfile
if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
return -1
}
if {![runto_main]} {
return -1
}
set pattern ".* = \\{int_array = \\{1, 2, 3, 4, 5\\}, double_array = \\{3.25, 5, 6.25, 1.325, -1.95\\}, char_array = \"abcde\"\\}"
gdb_test "p return_large_struct ()" $pattern
gdb_breakpoint "return_large_struct"
gdb_continue_to_breakpoint "Break in print_large_struct"
gdb_test "finish" $pattern "finish from return_large_struct"