I just realised the 12-bit unsigned offset can only reach an entire page for aligned accesses. Hopefully the vast majority of accesses are aligned anyway.

There’s still one form of ldr we aren’t trying to use – the PC-relative form with a 19-bit signed displacement in words ±1MB reach). It can only be used to load a word or doubleword (not a byte or halfword, or a floating-point type), and there’s no equivalent str form.

Code looks fine to me. I ran it through a few games + the tester and no issues from what I can tell.

A few before/after -str 90 -nothrottle runs:

shienryu (SH2)       414.39%   406.62%
s1945iii (SH2)      1319.27%  1296.48%
toyfight (SH4)       153.04%   168.68%
dc (SH4)             139.08%   142.06% (w/software list revilcv)
calspeed (MIPS)      332.66%   539.99%
kinst2 (MIPS)        729.66%   792.97%
gradius4 (PPC)       506.45%   501.04%
scud (PPC)           103.09%   103.20%

Very beneficial for MIPS, pretty much a wash otherwise.

Those MIPS results are kind of insane. Is it doing an inordinate number of fastram accesses or something?

Not sure what it was doing. Tried it again just now and the new code is still faster, but it's a much more normal delta.