Write too large with Firefox

[suyashmahar]

Some bitcode files for firefox generate Write too large error.

How to reproduce:

stack exec -- sys -c uninit -e prod -d firefox_ll_files/vp9_segmentation.ll-O2_p

Bitcode is available here.

And the error is raised here:

sys/src/Symex/Symex/Memory.hs

Line 181 in 821c4d7

when (blocksToRead > 2000) $ error "Write too large"

Which seems like some kind of arbitrary limit that can be changed? Changing it to 20k fixed the error. I'm not sure if that would break something in Sys.

(Using clang-9 and bleeding edge firefox)

-Suyash

CC @epyeh