On Fri, Nov 20, 2009 at 10:05 AM, Ian Bolton <bol...@icerasemi.com> wrote: > From some simple experiments (see below), it appears as though GCC aims > to > create a lop-sided tree when there are constants involved (func1 below), > but a balanced tree when there aren't (func2 below). > > Our assumption is that GCC likes having constants all near to each other > to > aid with tree-based optimisations, but I'm fairly sure that, when it > comes > to scheduling, it would be better to have a balanced tree, so sched has > more > choices about what to schedule next?
I think this would depend on the target architecture and instruction set: CISC vs RISC, many registers vs few registers, etc. I do not believe that GCC intentionally is trying to optimize for either, but I do not think there is a single, right answer. David
