[tz] ALL_STATE not "all" enough

enh enh at google.com
Wed May 14 23:57:29 UTC 2014


we're still having trouble with tzcode using unreasonable amounts of stack.
things were somewhat ameliorated by defining the oddly-named ALL_STATE.
that causes tzcode to allocate tzload's 'u_t' on the heap instead of the
stack. that takes about 40KiB off tzload's stack requirements, which was by
far the biggest offender.

unfortunately, later on in tzload there's a 'struct state' allocated on the
stack. on LP64, that's about 18KiB, which -- even if it's not 40KiB -- is
still unreasonable in one frame! LP32 is about 9KiB less, because our LP32
time_t was only 32-bit, so we've been getting away with it there ---
threads with 16KiB stacks could safely call tzcode functions. but this
isn't true for LP64.

(note that these rough figures are with TZ_MAX_TIMES at 1200 --- we haven't
yet bumped that to the 2000 it seems to be at head.)

we'll fix this in Android (the first hunk in
https://android-review.googlesource.com/#/c/94653/) but it would be nice if
this were fixed upstream too so we don't have to diverge more than we
already have.

 --elliott
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