The comment indicates the expectation that TiFree() is deferred-by-one,
which would be true if freeMalloc() was used but since the custom mmap()
allocator technically this is not true.
The TiFree() allocator is single-threaded and separate from libc so the
assumption is still kind of true but for different reasons
(single-threaded).
But since it doesn't really cost anything (other than a few lines of
code a human needs to read) the compiler would be expected to perform a
load (which it was going to do anyway) into a caller-saves register over
the function call.
Most of the other function state is invalidated anyway due to the heavy
linked-list navigation and low number of local variables, I would not
think there is much register allocation pressure.
TODO this code can be tested by confirming zero allocations are active
and by invalidating (poison) all fields inside TiFree().
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