An array or record converts by copying it when its layout differs from the
type it flows into (`{ id; name; owned?: true }[]` into a `{ id; name }[]`
parameter). JavaScript passes the same object, so a callee's `push`, index
stores and element-field writes reached the caller's array in Node but a
copy in the compiled program, and `===` against the original was false.
When an argument names an existing array or record whose layout has every
field of the parameter's type plus optional fields, a direct call of a
declared function now targets an instance of the function lowered with that
parameter bound to the argument's own type. The body reads and writes the
caller's value; a value it stores converts into the argument's layout by
completing the optional fields as absent. Instances are keyed by the
parameter layouts. An instance whose body does not lower is discarded with
everything it recorded, and the call converts as declared.
With the same rule, a non-exported function whose every return names such
a value returns its layout (including the parameter's element or field),
and a const keeps its initializer's layout when the initializer names an
existing value or is a call.
A local that only holds exact integers or NaN, such as one assigned from
an integer typed-array read, now keeps whether it is NaN beside its
integer view. Its reads, and sums, differences and products of them,
carry an i64 that holds the integer whenever the number is not NaN, so
an index check or a counted loop's guard tests that integer and the
ordered bit instead of converting the double back and checking that it
is an exact integer.
The thin link imported a callee of up to 100 instructions, LLVM's default,
into every partition that calls it, and each partition then optimized and
compiled its imported copies again. Partitioned programs now import callees
of up to 40 instructions. Programs that compile as one module are
unchanged.
require("buffer").Blob and timers.setTimeout now read as their global
spellings, so island-web-plumbing and misc-shims run past the SC2020
they stopped at and reach a later deferred SC1090: require() inside a
function in plumbing, and constructing a value that is not a program
class in misczoo. fetch-destructure reads fetch from the aliased global
object and matches Node.
Each call of a typed or untyped write, writev, transform, flush, final,
construct or destroy option callback allocated a closure and a box holding
the stream for its `callback` argument. The emitted thunks now take it
from scr_stream_done_closure, which keeps the last one on the stream state and
hands it out again while the stream holds its only reference and it has
no own properties. A callback the user kept (stored, or passed to
setImmediate or a promise) is not reused: the next call gets a new
closure, and the kept one keeps its own stream reference.
The cached closure holds the stream, so the stream drops it when it
emits 'close' and traces it, which lets the cycle collector reclaim a
stream dropped before it closes.
RUNTIME_ABI_VERSION goes from 46 to 47 for scr_stream_done_closure.
- A string held in a binding or returned by a call can be a missing element
read (undefined), so `head + PAD[j]` and `at(i) + PAD[j]` still add to NaN
when both are missing. Only string literals, templates and sums with such
an operand now count as always a string.
- `readdirSync(path, { recursive })` folds only the `true` and `false`
keywords. Any other flag expression, including one typed as a literal,
evaluates at run time for its effects and exceptions.
A speculative integer loop's fast copy exits to a copy that resumes the
failed iteration, and both read the header fields of the views they
access. GVN's load PRE moved the fast copy's read of a view's data
pointer ahead of the exit branch, to make the resume copy's read
redundant, and put a copy on the exit edge. The loop then kept its first
iteration in the loop, so the overflow checks of a value whose range is
known after one iteration stayed in every iteration, with a reload of the
data pointer.
A view held by a const local or a parameter that the loop does not rebind
is the same view in every iteration, and its length, data pointer and
shared storage never change. The loop's entry now reads them once, and the
element accesses of every copy use those values.
The store a constant choice emits for its arms used the first arm's
index expression, with the ranges proven inside that arm. When the index
is the compared local, `j === 0` narrows it to [0, 0] there, so the one
store, which also runs on the final else's path, converted the index to
an int32 from that range. For `j` = 4294967297 that conversion has no
defined result, and the bounds check that follows could accept it: an
out-of-bounds write could reach a valid element.
The store now reads such an index through the first comparison's
operand: the same local, read before the chain branches, so its range
holds on every path. An index that is another local is not narrowed by
the comparisons and is unchanged.
7515-net-socket-backpressure's server picks each connection's handling from
`mode` when it accepts it. The lookup client's 70000 bytes fit in the
kernel's buffers, so its 'drain', and the step that sets `mode` to "pause",
can run before the server accepts that connection. On macOS the accept can
come in a later kqueue batch: the server then paused the lookup socket,
never read its EOF, and the open connection kept the program running after
server.close(). The program now waits for that accept before it changes
`mode`. Its output is unchanged.
Chris Tate