Confirmed this change on using the swift-5.2-DEVELOPMENT-SNAPSHOT-2020-01-22-a
toolchain, Apple Swift version 5.2-dev (Swift d3f0448a4c).
Fixes rdar://problem/58717942
A previous commit [1] identified and fixed a benign race on
`_swiftEmptyArrayStorage`. Unfortunately, we have some code duplication
and the fix was not applied to all the necessary places. Essentially,
we need to ensure that the "empty array storage" object that backs many
"array like types" is never written to.
I tried to improve the test to capture this, however, it is very
finicky. Currently, it does not go red on my system even when I remove
the check to avoid the benign race in Release mode.
Relevant classes: Array, ArraySlice, ContiguousArray, ArrayBuffer,
ContiguousArrayBuffer, SliceBuffer.
[1] b9b4c789f3
rdar://55161564
This fixes a major perform bug involving array initialization from any
contiguously stored collection. This is not a recent regression. This fix
results in a 10,000X speedup (that's 4 zeros) for this code path:
func initializeFromSlice(_ a: [Int]) -> [Int] {
return Array<Int>(a[...])
}
A benchmark is included.
These should be audited since some might not actually need to be
@inlinable, but for now:
- Anything public and @inline(__always) is now also @inlinable
- Anything @usableFromInline and @inline(__always) is now @inlinable
* Removing FIXME from methods also marked always/never
* Unavailable/deprecated things don't need inlining
* Trivial implementations
* Enum namespaces
* Unsafe performance of opaque/raw pointer
* Dump doesn't need to be fast
* Error paths shouldn't require inlining
* Consistency with surrounding code
* Lazy performance needs specialization
* [stdlib] Update complexity docs for seq/collection algorithms
This corrects and standardizes the complexity documentation for Sequence
and Collection methods. The use of constants is more consistent, with `n`
equal to the length of the target collection, `m` equal to the length of
a collection passed in as a parameter, and `k` equal to any other passed
or calculated constant.
* Apply notes from @brentdax about complexity nomenclature
* Change `n` to `distance` in `index(_:offsetBy:)`
* Use equivalency language more places; sync across array types
* Use k instead of n for parameter names
* Slight changes to index(_:offsetBy:) discussion.
* Update tests with new parameter names
As a general rule, it is safe to mark the implementation of hash(into:) and _rawHashValue(seed:) for @_fixed_layout structs as inlinable.
However, some structs (like String guts, Character, KeyPath-related types) have complicated enough hashing that it seems counterproductive to inline them. Mark these with @effects(releasenone) instead.
