Object.getPrototypeOf of an Error answers Error.prototype when the error's view was built from its fields and its prototype is still the object the view was built with. After Object.setPrototypeOf(error, {}), it answers the object that was set.
A quotient x / Math.pow(2, n) divided on every evaluation, and a
division's latency bounds loops that carry the quotient, such as a key
that keeps its low bits with k - Math.floor(k / Math.pow(2, n)) *
Math.pow(2, n). A divisor that is a positive power of two from 2^-1022
to 2^1022 has a reciprocal that is a power of two too, whose bits are
0x7FE0000000000000 minus the divisor's, and the product with it is the
quotient for every dividend. The quotient now multiplies by that
reciprocal when the divisor's bits are such a power, and divides
otherwise.
Corpus 8180 compares the quotient with an ordinary division for every
integer exponent from -1080 to 1030, including divisors that are
subnormal, zero or infinite, and for exponents that are not integers.
Buffer.from(arrayBuffer, byteOffset[, length]) lowers to
buffer.poolFromDynRange with its operands as checked values. The int32
slot analysis treats any runtime helper with a checked-value argument
as a possible store into a live class instance unless the helper is
listed as read-only, so one such call dropped every int32 class field
fact in the program (tsc-ts's scanner makes one).
buffer.poolFromDynRange and buffer.poolFromDynOffset read their
operands (the ArrayBuffer's view after Node's offset and length
conversions, or a copy of a string's, array-like's or typed array's
values) and store into no class instance, so they join DYN_READ_ONLY.
`t[i]!` on a typed array always took the numeric element read, which is NaN
for an index outside the array. Node reads undefined there, so `t[n]! ===
t[n]!` was false instead of true, `${t[n]!}` was "NaN", and `typeof t[n]!`
was "number".
`t[i]!` now takes the numeric read only where its use converts the value to
a number. Where the use tells undefined from NaN (an equality, a template
span, `+` with a string, a comparison with a string, `!`, `typeof`, an array
literal element, or an argument whose parameter admits undefined, such as
`Object.is` and `String`), it reads undefined for an invalid index, like
`t[i]`. Returns and plain bindings keep the numeric read.
Corpus 7394.
An expected regex or string read from a JavaScript object literal's
field is a checked-dynamic value while its checker type is RegExp or
string. assert.throws chose its regex comparison from the checker type
and passed the value unconverted, an internal compiler error, and
assert.match and the expected-object form refused it. Such a value now
converts to the regex or string its type names.
The checker resolves an overloaded call whose argument is `any` to the
first overload that argument satisfies, but in JavaScript the value can
select another one: generateKeyPairSync("ec", options) returns KeyObjects
or PEM strings by the options, and digest(encoding) returns a Buffer when
the encoding is undefined. The result was converted to the first
overload's return type, so such calls threw a TypeError where Node
returns the other overload's value.
When a checked-dynamic argument could take another overload whose return
type differs (trailing untyped or undefined arguments may also be
absent), the call's result in a JavaScript source is checked-dynamic. So
are the unannotated bindings it initializes, destructured or not, and
the unannotated functions that return it. fs.globSync keeps choosing its
result form from the resolved overload, since the runtime checks that
withFileTypes agrees with it.
An Error's view had no prototype or a holder of its default name and
message, so Object.getPrototypeOf(new Error()) was Object.prototype or a
fresh object. A view of an error built as an Error, whose prototype is
still the one its view starts with, now answers Error.prototype.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A while loop over typed arrays also versioned when its only checks were
thread-owned receivers or static indices. A worker's job loop such as
`while ((job = Atomics.load(next, 0)) < count) { ...; run(job) }` then
got a second copy whose guard fails whenever the array is shared, and
the doubled call kept the job function from being inlined. A while loop
now versions only when it has an access at one of its counters. Other
while loops compile as they did before they could version.
A class instance converted to an untyped value was boxed in a capsule of
its static class. Before any member table read it,
%dyn.class.normalize tested it against each subclass and boxed it again
at the instance's own class: two capsules per crossing for every value
of a class with subclasses, and the subclass tests on every member read.
After the dispatch tables settle, each conversion of a value whose static
JavaScript class has a normalization branch now calls
%dyn.class.boxExact:<Class>, which runs the same subclass tests in the
same order once, at the conversion. The capsule is created at the exact
class, and normalization falls through for it. TypeScript hierarchies,
classes that are never boxed, and hierarchies without subclasses are
untouched.
zod 3, z.array(Order).parse over 500 orders: 178.5M -> 174.4M
instructions per round (-2.3%).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Chris Tate