https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109592
--- Comment #8 from Feng Wang <wangfeng at eswincomputing dot com> --- (In reply to Jeffrey A. Law from comment #7) > Attached is what I cobbled together. It doesn't use magic numbers. But it > doesn't yet handle zero extensions in the simplify-rtx code. But I think it > shows the overall direction fairly well. Sorry, I can't find the attachement. I think we need to consider more here,such as the cost of zero/sign extensions, only convert shifts to zero/sign extensions when it cost less in certain hardware architectures. At the same we also consider the shift ins is more suitable for combine pass.Maybe We should consider that whether the conversion prevents a better combination in combine pass(I need study a suitable test case).
