YJIT: Respect destination num_bits on STUR (#6848)

yjit/src/asm/arm64/mod.rs

@@ -906,7 +906,7 @@ pub fn stur(cb: &mut CodeBlock, rt: A64Opnd, rn: A64Opnd) {
             assert!(rn.num_bits == 32 || rn.num_bits == 64);
             assert!(mem_disp_fits_bits(rn.disp), "Expected displacement to be 9 bits or less");
 
-            LoadStore::stur(rt.reg_no, rn.base_reg_no, rn.disp as i16, rt.num_bits).into()
+            LoadStore::stur(rt.reg_no, rn.base_reg_no, rn.disp as i16, rn.num_bits).into()
         },
         _ => panic!("Invalid operand combination to stur instruction.")
     };
@@ -1499,10 +1499,15 @@ mod tests {
     }
 
     #[test]
-    fn test_stur() {
+    fn test_stur_64_bits() {
         check_bytes("6a0108f8", |cb| stur(cb, X10, A64Opnd::new_mem(64, X11, 128)));
     }
 
+    #[test]
+    fn test_stur_32_bits() {
+        check_bytes("6a0108b8", |cb| stur(cb, X10, A64Opnd::new_mem(32, X11, 128)));
+    }
+
     #[test]
     fn test_sub_reg() {
         check_bytes("200002cb", |cb| sub(cb, X0, X1, X2));