+# Copyright 2019 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 tests GDB's ability to handle 6 and 8 byte instructions in the
+# RISC-V prologue scanner. These instruction should be ignored, but
+# should not result in an error that interrupts the debug session.
+#
+# Each of the files riscv-unwind-long-insn-*.s include a function
+# (func) that contains a fake long instruction (6 or 8 bytes) in the
+# prologue. We trick GDB into parsing the fake instruction by tail
+# calling from a different function, 'bar' to the middle of 'func'.
+
+if {![istarget "riscv*-*-*"]} {
+ verbose "Skipping ${gdb_test_file_name}."
+ return
+}
+
+foreach_with_prefix {insn_size} {6 8} {
+ standard_testfile riscv-unwind-long-insn.c \
+ riscv-unwind-long-insn-${insn_size}.s
+
+ set testfile "${testfile}-${insn_size}"
+ if {[prepare_for_testing "failed to prepare" $testfile \
+ "$srcfile $srcfile2" debug]} {
+ return -1
+ }
+
+ if ![runto_main] then {
+ fail "can't run to main"
+ return 0
+ }
+
+ gdb_breakpoint "bar"
+ gdb_continue_to_breakpoint "bar"
+
+ # This next single instruction step takes us through a tail-call
+ # from 'bar' into 'func'.
+ gdb_test "si" "func \(\).*"
+
+ # Now check that we have a sane backtrace.
+ gdb_test "bt" \
+ [multi_line \
+ "#0\[ \t\]*func \\\(\\\) at .*$srcfile2:\[0-9\]+" \
+ "#1\[ \t\]*$hex in main \\\(\\\) at .*$srcfile:\[0-9\]+"] \
+ "Backtrace to the main frame"
+
+ # Finally finish, and we should end up back in main.
+ gdb_test "finish" "main \\\(\\\) at .*$srcfile:.*"
+}