[PATCH 00/10] Clean up fb's 64-bit-wide path

[Adam Jackson]

fb is somewhat independent of machine word size, in that the code is written
in terms of abstract types.  There's code to handle FbBits of either 32 or
64 bits; the latter has bitrotted, and no longer compiles.  I was hoping to
test whether the 64-bit path was any faster on current 64-bit machines, so
this series (1 through 8 anyway) gets it back to the point of building.

The last two are more rough sketches of what you'd need to do to make it
actually work; I don't intend for them to be merged as is.

In case you were wondering how it performs: slightly worse, I think?  Which
makes sense, if your pixels are smaller than your word size then you're
going to be spending time masking pixels together that you wouldn't if they
matched, and you're not really going to gain much write throughput since d$
writeback will combine adjacencies anyway.  Given that X11 fundamentally can't
cope with >32 bit pixels, it might make sense to just drop the 64-bit path
entirely.

- ajax