[gdb/testsuite] Fix gdb.arch/amd64-disp-step-self-call.exp on freebsdHEADmaster

On x86_64-freebsd, with test-case gdb.arch/amd64-disp-step-self-call.exp, I
run into:
...
(gdb) continue
Continuing.

Program received signal SIGBUS, Bus error.
Object-specific hardware error.
0x000000080051492c in alarm () from /lib/libc.so.7
(gdb) FAIL: $exp: continue to breakpoint: test_call
...

The behaviour is not specific to gdb, it can be reproduced by running the
test-case executable:
...
$ ./outputs/gdb.arch/amd64-disp-step-self-call/amd64-disp-step-self-call
Bus error (core dumped)
$
...

The bus error happens when executing this instruction in alarm:
...
0000000000093910 <alarm>:
   ...
   9392c: 0f 29 45 d0                  	movaps	%xmm0, -0x30(%rbp)
...
because $rbp is not 16-byte aligned.

This can be fixed by adding the missing frame setup instructions at the start
of main in amd64-disp-step-self-call.S:
...
 main:
+	pushq	%rbp
+	movq	%rsp, %rbp
...

Instead, fix this by moving main from the assembly file to the c file, which
has the same effect.

Also remove the done label, which looks like a copy-past left-over.  Instead,
add an unreachable function and use it where appropriate.

Do the same for i386 case (which makes the source files identical for the
amd64 and i386 case, but I decided to leave it like that).

Tested on x86_64-freebsd and x86_64-linux.

4 files changed, 38 insertions, 44 deletions

diff --git a/gdb/testsuite/gdb.arch/amd64-disp-step-self-call-alarm.c b/gdb/testsuite/gdb.arch/amd64-disp-step-self-call-alarm.c
index 03b868c..0fb2904 100644
--- a/gdb/testsuite/gdb.arch/amd64-disp-step-self-call-alarm.c
+++ b/gdb/testsuite/gdb.arch/amd64-disp-step-self-call-alarm.c
@@ -16,9 +16,27 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <unistd.h>
+#include <stdlib.h>
+
+extern void test_call (void);
+
+void
+unreachable (void)
+{
+  abort ();
+}
 
 void
 setup_alarm (void)
 {
   alarm (300);
 }
+
+int
+main ()
+{
+  setup_alarm ();
+  test_call ();
+  unreachable ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/amd64-disp-step-self-call.S b/gdb/testsuite/gdb.arch/amd64-disp-step-self-call.S
index 78a6859..20a8eb7 100644
--- a/gdb/testsuite/gdb.arch/amd64-disp-step-self-call.S
+++ b/gdb/testsuite/gdb.arch/amd64-disp-step-self-call.S
@@ -18,33 +18,12 @@
    handling.  */
 
 	.text
-
-	.global main
-main:
-	nop
-
-	callq	setup_alarm
-
-	nop
-
-/***********************************************/
-
-/* test call/ret */
-
 	.global test_call
 test_call:
 	call test_call
-	nop
+	call unreachable
 	.global test_ret_end
 test_ret_end:
 	nop
 
-/***********************************************/
-
-/* all done */
-
-done:
-	mov $0,%rdi
-	call exit
-	hlt
 	.section	.note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/gdb.arch/i386-disp-step-self-call-alarm.c b/gdb/testsuite/gdb.arch/i386-disp-step-self-call-alarm.c
index 03b868c..0fb2904 100644
--- a/gdb/testsuite/gdb.arch/i386-disp-step-self-call-alarm.c
+++ b/gdb/testsuite/gdb.arch/i386-disp-step-self-call-alarm.c
@@ -16,9 +16,27 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <unistd.h>
+#include <stdlib.h>
+
+extern void test_call (void);
+
+void
+unreachable (void)
+{
+  abort ();
+}
 
 void
 setup_alarm (void)
 {
   alarm (300);
 }
+
+int
+main ()
+{
+  setup_alarm ();
+  test_call ();
+  unreachable ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/i386-disp-step-self-call.S b/gdb/testsuite/gdb.arch/i386-disp-step-self-call.S
index 466e50c..20a8eb7 100644
--- a/gdb/testsuite/gdb.arch/i386-disp-step-self-call.S
+++ b/gdb/testsuite/gdb.arch/i386-disp-step-self-call.S
@@ -18,33 +18,12 @@
    handling.  */
 
 	.text
-
-	.global main
-main:
-	nop
-
-	call	setup_alarm
-
-	nop
-
-/***********************************************/
-
-/* test call/ret */
-
 	.global test_call
 test_call:
 	call test_call
-	nop
+	call unreachable
 	.global test_ret_end
 test_ret_end:
 	nop
 
-/***********************************************/
-
-/* all done */
-
-done:
-	pushl $0
-	call exit
-	hlt
 	.section	.note.GNU-stack,"",@progbits