Looks like a known fail:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101674

diff --git a/gcc/testsuite/gcc.dg/uninit-pred-9_b.c b/gcc/testsuite/gcc.dg/uninit-pred-9_b.c
index 53c4a5399ea..c2b043f5019 100644
--- a/gcc/testsuite/gcc.dg/uninit-pred-9_b.c
+++ b/gcc/testsuite/gcc.dg/uninit-pred-9_b.c
@@ -17,7 +17,7 @@ int foo (int n, int l, int m, int r)
 
   if (l > 100)
     if ( (n <= 9) &&  (m < 100)  && (r < 19) )
-      blah(v); /* { dg-bogus "uninitialized" "bogus warning" { xfail powerpc64*-*-* cris-*-* riscv*-*-* } } */
+      blah(v); /* { dg-bogus "uninitialized" "bogus warning" { xfail powerpc64*-*-* cris-*-* riscv*-*-* s390*-*-* } } */
 
   if ( (n <= 8) &&  (m < 99)  && (r < 19) )
       blah(v); /* { dg-bogus "uninitialized" "pr101674" { xfail mmix-*-* } } */
