> > Some of the generated tcg code is not very optimal, for example a > > single vld4.8 instruction can generate over 250 tcg ops. I did some > > optimizations and got it under 200 but do you think it could be an > > issue that a single instruction can expand to so many tcg ops? I mean > > besides the fact that it causes TBs for only one or two guest > > instructions to be generated. > > Fabrice wrote this (tcg/README): > > Don't hesitate to use helpers for complicated or seldom used target > intructions. There is little performance advantage in using TCG to > implement target instructions taking more than about twenty TCG > instructions. > > How applicable is it, I can't say. It'd probably be a good thing > to benchmark the two versions, TCG vs helper.
The problem is that you can not do memory accesses from within a helper function. Paul
