[gdb/testsuite] Fix gdb.base/reggroups.exp with check-read1

On aarch64-linux, with make target check-read1, I run into:
...
(gdb) info reg vector^M
  ...
d19            {f = 0x0, u = 0x0, s = 0x0} {f =FAIL: gdb.base/reggroups.exp: fetch reggroup regs vector (timeout)
 0, u = 0, s = 0}^M
...

The problem is that while (as documented) the corresponding gdb_test_multiple
doesn't work for vector registers, it doesn't skip them either.  This causes
the timeout, and it also causes the registers after a vector register not to
be found.

Fix this by using -lbl style matching.

Make which reggroups and registers are found more explicit using verbose -log,
which makes us notice that regnames with underscores are skipped, so fix that
as well.

While we're at it, this:
...
set invalid_register_re "Invalid register .*"
...
and this:
...
       -re $invalid_register_re {
           fail "$test (unexpected invalid register response)"
       }
...
means that the prompt may or may not be consumed.  Fix this by limiting the
regexp to one line, and using exp_continue.

While we're at it, improve readability of the complex regexp matching a single
register by factoring out regexps.

Tested on aarch64-linux and x86_64-linux.

1 files changed, 21 insertions, 7 deletions

diff --git a/gdb/testsuite/gdb.base/reggroups.exp b/gdb/testsuite/gdb.base/reggroups.exp
index f96153b..56c00e5 100644
--- a/gdb/testsuite/gdb.base/reggroups.exp
+++ b/gdb/testsuite/gdb.base/reggroups.exp
@@ -27,7 +27,7 @@ if {![runto_main]} {
     return 0
 }
 
-set invalid_register_re "Invalid register .*"
+set invalid_register_re "Invalid register \[^\r\n\]*"
 
 # Fetch all reggroups from 'maint print reggroups'.
 
@@ -51,6 +51,7 @@ proc fetch_reggroups {test} {
 	}
     }
 
+    verbose -log "found reggroups: $reggroups"
     return $reggroups
 }
 
@@ -78,21 +79,34 @@ proc fetch_reggroup_regs {reggroup test} {
     # xmm0           {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, ... }}
     #
     set regs {}
-    gdb_test_multiple "info reg $reggroup" $test {
-	-re "info reg $reggroup\r\n" {
+    set have_invalid_register_fail 0
+    set re_regname "\[0-9a-zA-Z_-\]+"
+    set re_hws "\[ \t\]+"
+    set re_hs "\[^\n\r\]+"
+    set re_eol "\r\n"
+    set re_lookahead_eol "(?=$re_eol)"
+    gdb_test_multiple "info reg $reggroup" $test -lbl {
+	-re "^info reg $reggroup" {
 	    exp_continue
 	}
-	-re "^(\[0-9a-zA-Z-\]+)\[ \t\]+(0x\[0-9a-f\]+)\[ \t\]+(\[^\n\r\]+)\r\n" {
+	-re "^${re_eol}($re_regname)$re_hws$::hex$re_hws${re_hs}$re_lookahead_eol" {
 	    lappend regs $expect_out(1,string)
 	    exp_continue
 	}
 	-re $invalid_register_re {
-	    fail "$test (unexpected invalid register response)"
+	    set have_invalid_register_fail 1
+	    exp_continue
 	}
-	-re "$gdb_prompt $" {
-	    pass $test
+	-re -wrap "" {
+	    if { $have_invalid_register_fail } {
+		fail "$test (unexpected invalid register response)"
+	    } else {
+		pass $test
+	    }
 	}
     }
+
+    verbose -log "found regs in reggroup $reggroup: [join $regs]"
     return $regs
 }