Omit shift when zero

Author: Grarak

src/jit/assembler/block_asm.rs

@@ -216,7 +216,13 @@ impl BlockAsm {
                         };
                         match value {
                             ShiftValue::Reg(shift_reg) => unsafe { vixl::Operand::new5(map_reg, shift_type.into(), self.reg_alloc.get_guest_map(*shift_reg).into()) },
-                            ShiftValue::Imm(shift_imm) => unsafe { vixl::Operand::new4(map_reg, shift_type.into(), *shift_imm as u32) },
+                            ShiftValue::Imm(shift_imm) => {
+                                if *shift_imm == 0 {
+                                    unsafe { vixl::Operand::new2(map_reg) }
+                                } else {
+                                    unsafe { vixl::Operand::new4(map_reg, shift_type.into(), *shift_imm as u32) }
+                                }
+                            }
                         }
                     }
                 }