Revert "Restart nSIM and GDB each time for GCC tests"

This reverts commit 880aefa.

Author: anthony-kolesov

dejagnu/baseboards/arc-nsim.exp

@@ -69,7 +69,7 @@ set_board_info ldscript ""
 # Call to nsim_open will set the netport (used by gdb-comm) as well as setting
 # up nSim specific data.
 set port [exec [file dirname $env(DEJAGNU)]/get-random-port.sh]
-set_board_info nsim_port $port
+nsim_open $port
 
 # GDB protocol to be used
 set_board_info gdb_protocol "remote"

dejagnu/nsim-extra.exp

@@ -111,31 +111,41 @@ proc arc-nsim_reboot { connhost args } {
     return 1
 }
 
-# There are problems with GDB loading new application with `file` command, at
-# least when new file has same filename as the old one. That problem is
-# not-deterministic and I wasn't able to trace down the source, however I see
-# that this happened between 7.5 and 7.6. To avoid troubles - restart GDB
-# completely. Restarting nSIM is not really required if it's registers are
-# reset, however for a good measure it is better to restart it, at the price of
-# performance penalty for restarting, of course.
-rename gdb_comm_start arc_saved_gdb_comm_start
-
-proc gdb_comm_leave { } {
-    verbose "ARC specific gdb_comm_leave"
-    nsim_close
-    quit_gdb
-}
+# 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
+    }
 
-proc gdb_comm_start { dest } {
-    global board board_info
+    remote_send host "set \$pc=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
+    }
 
-    if { ![info exists board] } {
-	set board $dest
+    remote_send host "set \$blink=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
     }
 
-    verbose "ARC specific gdb_comm_start"
-    nsim_open [target_info nsim_port]
-    arc_saved_gdb_comm_start $dest
+    remote_send host "set \$lp_count=0\n"
+    remote_expect host 10 {
+	-re ".*$gdb_prompt $" {}
+    }
+
+    arc_saved_gdb_comm_go_idle
 }
 
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