tests/tcg/s390x: Test MDEB and MDEBR

Add a small test to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Message-Id: <20230704081506.276055-12-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/tcg/s390x/Makefile.target

@@ -38,6 +38,7 @@ TESTS+=ex-branch
 TESTS+=mxdb
 TESTS+=epsw
 TESTS+=larl
+TESTS+=mdeb
 
 cdsg: CFLAGS+=-pthread
 cdsg: LDFLAGS+=-pthread

tests/tcg/s390x/mdeb.c

@@ -0,0 +1,30 @@
+/*
+ * Test the MDEB and MDEBR instructions.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <assert.h>
+#include <stdlib.h>
+
+int main(void)
+{
+    union {
+        float f[2];
+        double d;
+    } a;
+    float b;
+
+    a.f[0] = 1.2345;
+    a.f[1] = 999;
+    b = 6.789;
+    asm("mdeb %[a],%[b]" : [a] "+f" (a.d) : [b] "R" (b));
+    assert(a.d > 8.38 && a.d < 8.39);
+
+    a.f[0] = 1.2345;
+    a.f[1] = 999;
+    b = 6.789;
+    asm("mdebr %[a],%[b]" : [a] "+f" (a.d) : [b] "f" (b));
+    assert(a.d > 8.38 && a.d < 8.39);
+
+    return EXIT_SUCCESS;
+}