On Fri, 1 Jun 2018, Richard Biener wrote: > For code-generating adjacent inserts wouldn't it be more efficient > to do > > accum = first-to-be-inserted-val; > accum <<= shift-to-next-inserted-val; > accum |= next-to-be-inserted-val; > ... > accum <<= final-shift; > > instead of shifting the to-be-inserted value?
Perhaps I'm missing some context, but I don't see why this is expected to be more efficient. This sequence has both ors and shifts on the critical path, whereas shifting to-be-inserted values has more parallelism (shifts are then independent of ors), and even allows ors to be reassociated, shortening the critical path even more. Alexander
