I remembered and ultimately found a source for a workaround for the serialising on flags problem, intel paper at https://web.archive.org/web/20150131061304/http

I remembered and ultimately found a source for a workaround for the serialising on flags problem, intel paper at https://web.archive.org/web/20150131061304/http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-large-integer-arithmetic-paper.pdf https://web.archive.org/web/20150131061304/http://www.intel.... amounts to new instructions with better behaviour for ILP