Ensure that cpu state is reset before tests on nSIM GDB board

Non-reseted board can cause issues while running next test and even crash
GDB due to inconsistency between old registers state and new debug info.

Signed-off-by: Anton Kolesov <[email protected]>

Author: anthony-kolesov

dejagnu/nsim-extra.exp

@@ -111,4 +111,41 @@ proc arc-nsim_reboot { connhost args } {
     return 1
 }
 
+# By default between tests GDB will do `target exec`, then will reconnect to
+# target with `target remote`. As a result target will be left at the state of
+# end of previous test, likely in `exit()`. When GDB will reconnect with new
+# application, it will automatically try to unwind trace using old register
+# values, that will happen immediately after `target remote` before `load` that
+# will overwrite PC register. Consequently old-register values will be used and
+# in some unfortunate cases that might cause a failed assert in GDB. To avoid
+# possible issues this board should redefine gdb_comm_go_idle, so before
+# disconnecting from target GDB will reset crucial registers to 0.
+rename gdb_comm_go_idle arc_saved_gdb_comm_go_idle
+
+proc gdb_comm_go_idle {} {
+    global gdb_prompt
+
+    # Original gdb_comm_go_idle does the same, so it is save to not call it.
+    if {![board_info host exists fileid]} {
+	return -1
+    }
+
+    remote_send host "set \$pc=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
+    }
+
+    remote_send host "set \$blink=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
+    }
+
+    remote_send host "set \$lp_count=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
+    }
+
+    arc_saved_gdb_comm_go_idle
+}
+
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