[gdb/testsuite] Fix timeouts in gdb.threads/step-over-thread-exit.exp

Once in a while, I run into a timeout in test-case
gdb.threads/step-over-thread-exit.exp:
...
(gdb) continue^M
Continuing.^M
[New Thread 0xfffff7cff1a0 (LWP 2874854)]^M
^M
Thread 97 "step-over-threa" hit Breakpoint 2, 0x0000000000410314 in \
  my_exit_syscall () at gdb/testsuite/lib/my-syscalls.S:74^M
74      SYSCALL (my_exit, __NR_exit)^M
(gdb) [Thread 0xfffff7cff1a0 (LWP 2874853) exited]^M
FAIL: $exp: step_over_mode=displaced: non-stop=on: target-non-stop=on: \
  schedlock=off: cmd=continue: ns_stop_all=0: iter 95: continue (timeout)
...

I can reproduce it more frequently by running with taskset -c <slow core id>.

Fix this by using -no-prompt-anchor.

This requires us to add -no-prompt-anchor to proc gdb_test_multiple.

Tested on aarch64-linux.

PR testsuite/32489
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32489

1 files changed, 8 insertions, 1 deletions

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 10d7a75..a86d74d 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1022,6 +1022,10 @@ proc command_to_message { command } {
 #   if one of them matches.  If MESSAGE is empty COMMAND will be used.
 # -prompt PROMPT_REGEXP specifies a regexp matching the expected prompt
 #   after the command output.  If empty, defaults to "$gdb_prompt $".
+# -no-prompt-anchor specifies that if the default prompt regexp is used, it
+#   should not be anchored at the end of the buffer.  This means that the
+#   pattern can match even if there is stuff output after the prompt.  Does not
+#   have any effect if -prompt is specified.
 # -lbl specifies that line-by-line matching will be used.
 # EXPECT_ARGUMENTS will be fed to expect in addition to the standard
 #   patterns.  Pattern elements will be evaluated in the caller's
@@ -1121,6 +1125,7 @@ proc gdb_test_multiple { command message args } {
 
     set line_by_line 0
     set prompt_regexp ""
+    set prompt_anchor 1
     for {set i 0} {$i < [llength $args]} {incr i} {
 	set arg [lindex $args $i]
 	if { $arg  == "-prompt" } {
@@ -1128,6 +1133,8 @@ proc gdb_test_multiple { command message args } {
 	    set prompt_regexp [lindex $args $i]
 	} elseif { $arg == "-lbl" } {
 	    set line_by_line 1
+	} elseif { $arg == "-no-prompt-anchor" } {
+	    set prompt_anchor 0
 	} else {
 	    set user_code $arg
 	    break
@@ -1139,7 +1146,7 @@ proc gdb_test_multiple { command message args } {
 	error "Too few arguments to gdb_test_multiple"
     }
 
-    set prompt_regexp [fill_in_default_prompt $prompt_regexp true]
+    set prompt_regexp [fill_in_default_prompt $prompt_regexp $prompt_anchor]
 
     if { $message == "" } {
 	set message [command_to_message $command]