The module cache was added in 97ce26b1 (April 16, 2011),
but it was accidentally disabled in e9721058 (May 5, 2011).
This time, I figured out a way to test whether the cache is
working (other than to benchmark examples, which is how I
discovered that it wasn't working).
For example,
(define-for-syntax (f x) (g x))
(define-for-syntax (g y) y)
is now allowed. The unbound-variable check for phase 1
and up is delayed until after the module body is partially expanded.
The JIT and bytecode compiler disagreed on the definition of
"constant". Now there are two levels: "constant" means constant across
all instantiations, and "fixed" means constant for a given instantation.
The JIT uses this distinction to generate direct-primitive calls
or not. (Without the distinction, a direct jump to `reverse' could
be wrong, because `racket/base' might get instantiated with the
JIT disabled or not.)
Also, fixed a bug in the JIT's `vector-set!' code in the case that
the target vector is a top-/module-level reference that is ready,
fixed, or constant.
More specifically, for a string of length N and a match that
only looks at the first M characters, the complexity of
`regexp-match' is now O(M) instead of O(N). This allows
`regexp-split' to be O(N) for a string instead of O(N^2).
Also, fixed a bug in non-greedy matching that could affect
both long strings and input ports.
Commit 311d55b5cf fixed a shallow bug that masked a deeper
bug in the interaction of local bindings and module-level
bindings. This one fixes the deeper problem, which is that
the recursive resolution that ignores module bindings should
start from the beginning of the wraps, not the wrap after
a module renaming.
Closes PR 12116
Shared locking now allowed only on input port, and exclusive
locking is allowed only on output ports, which allows an implementation
via fcntl(...,F_SETLK,...).
Although a future thread used an atomic compare-and-swap to
set "is a list" or "not a list" flag on pairs via the
JIT-implemented `list?', the hashing function in the runtime
thread did not; as a result, it might be possible to lose
a hash code due to cache inconsistency (although I'm not
sure it's actually possible, and I couldn't trigger a problem
with a test). Most of the changes are related to using
an atomic compare-and-swap when setting a hash code, as
well as clean-ups to related code. Processor-count tests
avoid using atomic compare-and-swap on uniprocessors, which
might not support the relevant machine instructions.
As significantly, the compare-and-swap operation for the
JIT-implemented `list?' did not actually set flags on
a pair that has a hash code. This could lead to `list?'
tests that were not constant time (but only if the relevant
pair's `eq?' hash code had been used previously).
