“ The drawback is that upon interactions with the system the registers need to be flushed to the stack, necessitating a long sequence of writes to memory of data that is often mostly garbage. Register windows was a bad idea that was caused by simulation studies that considered only programs in isolation, as opposed to multitasking workloads, and by considering compilers with poor optimization. It also caused considerable problems in implementing high-end Sparc processors such as the SuperSparc, although more recent implementations have dealt effectively with the obstacles. Register windows is now part of the compatibility legacy and not easily removed from the architecture.
