This introduces speculative constants, allowing FIFO writes to be
optimized in more places.
It also clarifies the guarantees of the FIFO optimization, changing
the location of some of the checks and potentially avoiding redundant
checks.
The gather pipe optimization postpones checking the FIFO until the end
of the current block (or 32 bytes have been written). This is usually
safe, but is not correct across EIEIO instructions.
This is inferred from a block in NBA2K11 which synchronizes the FIFO
by writing a byte to it, executing eieio, and checking if PI_FIFO_WPTR
has changed. This is not currently an issue, but will become an issue
if the gather pipe optimization is applied to more stores.
In TimeSplitters: Future Perfect, PerfQuery is used to detect
the visibility of lights and draw coronas. 25 points are drawn
for each light. However, the returned count was incorrectly
being divided by four leading to dim coronas.
Using 4x antialiasing was a workaround because of a bug where
antialiasing multiplied the PerfQuery results. This commit
fixes that bug too (but only for OpenGL).
hthh