[PATCH 2/2] gdb/testsuite: Add test for AArch64 Scalable Vector Extension

[Thiago Jung Bauermann via Gdb-patches <gdb-patches@sourceware.org>]

It exercises a bug that GDB previously had where it would lose track of
some registers when the inferior changed its vector length.
---
 gdb/testsuite/gdb.arch/aarch64-sve.c   | 61 +++++++++++++++++++
 gdb/testsuite/gdb.arch/aarch64-sve.exp | 81 ++++++++++++++++++++++++++
 gdb/testsuite/lib/gdb.exp              |  4 ++
 gdb/testsuite/lib/mi-support.exp       |  4 --
 4 files changed, 146 insertions(+), 4 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sve.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-sve.exp

diff --git a/gdb/testsuite/gdb.arch/aarch64-sve.c b/gdb/testsuite/gdb.arch/aarch64-sve.c
new file mode 100644
index 000000000000..f56a5799a522
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-sve.c
@@ -0,0 +1,61 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   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/>.  */
+
+/* Exercise AArch64's Scalable Vector Extension.  */
+
+/* This test was based on QEMU's sve-ioctls.c test file, which at the time had
+   the following copyright statement:
+
+   Copyright (c) 2019 Linaro Ltd
+
+   SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <stdio.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+
+static int do_sve_ioctl_test(void)
+{
+    int i, res, init_vl;
+
+    res = prctl(PR_SVE_GET_VL, 0, 0, 0, 0);
+    if (res < 0) {
+        printf("FAILED to PR_SVE_GET_VL (%d)", res);
+        return -1;
+    }
+    init_vl = res & PR_SVE_VL_LEN_MASK;
+
+    for (i = init_vl; i > 15; i /= 2) {
+        printf("Checking PR_SVE_SET_VL=%d\n", i);
+        res = prctl(PR_SVE_SET_VL, i, 0, 0, 0, 0); /* break here */
+        if (res < 0) {
+            printf("FAILED to PR_SVE_SET_VL (%d)", res);
+            return -1;
+        }
+    }
+    return 0;
+}
+
+int main(int argc, char **argv)
+{
+    if (getauxval(AT_HWCAP) & HWCAP_SVE) {
+        return do_sve_ioctl_test();
+    } else {
+        printf("SKIP: no HWCAP_SVE on this system\n");
+        return 1;
+    }
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-sve.exp b/gdb/testsuite/gdb.arch/aarch64-sve.exp
new file mode 100644
index 000000000000..5c4a9fa2d770
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-sve.exp
@@ -0,0 +1,81 @@
+# 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/>.
+
+# Test a binary that uses SVE and exercise SVE-related scenarios.
+
+if {![is_aarch64_target]} {
+    verbose "Skipping ${gdb_test_file_name}."
+    return
+}
+
+standard_testfile
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return
+}
+
+set linespec ${srcfile}:[gdb_get_line_number "break here"]
+
+if ![runto ${linespec}] {
+    return
+}
+
+# Count number of lines in "info registers" output.
+proc count_info_registers {} {
+    global gdb_prompt
+    set ret 0
+
+    gdb_test_multiple "info registers" "" {
+	-re ".*$gdb_prompt $" {
+	    set ret [count_newlines $expect_out(buffer)]
+	}
+    }
+
+    return ${ret}
+}
+
+# The test executable halves the vector length in a loop, so loop along
+# to check it.
+set i 0
+while 1 {
+    incr i
+
+    set lines_before [count_info_registers]
+
+    gdb_test "next" ".*if .res < 0. ." "step over prctl iteration ${i}"
+
+    set lines_after [count_info_registers]
+
+    # There was a bug where GDB would lose track of some registers when the
+    # vector length changed.  Make sure they're still all there.
+    if {${lines_before} == ${lines_after}} {
+	pass "same number of registers iteration ${i}"
+    } else {
+	fail "same number of registers iteration ${i}"
+    }
+
+    gdb_test_multiple "continue" "" {
+	-re ".*Breakpoint $decimal, do_sve_ioctl_test .*$gdb_prompt $" {
+	    # Next iteration.
+	}
+	-re "Inferior 1 .* exited normally.*$gdb_prompt $" {
+	    # We're done.
+	    break
+	}
+	-re "$gdb_prompt $" {
+	    fail "unexpected output"
+	    break;
+	}
+    }
+}
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index a8f25b5f0dd5..3a8b880c074d 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -7885,6 +7885,10 @@ proc multi_line_input { args } {
     return [join $args "\n"]
 }
 
+proc count_newlines { string } {
+    return [regexp -all "\n" $string]
+}
+
 # Return the version of the DejaGnu framework.
 #
 # The return value is a list containing the major, minor and patch version
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index ca56e12b06bf..e821c0f6914f 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -1728,10 +1728,6 @@ set mi_autotest_data ""
 # The name of the source file for autotesting.
 set mi_autotest_source ""
 
-proc count_newlines { string } {
-    return [regexp -all "\n" $string]
-}
-
 # Prepares for running inline tests in FILENAME.
 # See comments for mi_run_inline_test for detailed
 # explanation of the idea and syntax.