The primary focus of this patch set is to reduce the number of
helpers that modify TCG globals, and thus increase the lifetime
of those globals within each TB, and thus decrease the number
of times that tcg must spill and fill them from backing store.
This patch set is relative to the "Improve sparc register windows"
patches, which turned all of the integer registers into TCG globals.
Thus this patch set improves the effect of the previous patch set.
As a byproduct, I also implement the bulk of the interesting v9 ASIs
inline, thus exposing e.g. the little-endian loads and stores as
simple tcg operations.