This commit is the result of auditing the following files:
* StringBuffer.swift
* StringCharacterView.swift
* StringCore.swift
* StringInterpolation.swift.gyb
* StringLegacy.swift
This code as written is not sound and should not type check
for non-final classes conforming to SequenceType (eg, NSArray).
Instead, capture the base of the call from the preprocess closure
passed in. The closure is @noescape, so it should be equivalent.
At DaveA's suggestion, I took a mostly mechanical approach to this:
pointers and numeric types start using += 1, and indexes use
i = i.successor(). The index model is likely to be revised in
Swift 3 anyway, so micro-optimizing this code syntactically isn't
super important.
There is some performance concern of this patch, since some
in-place succesor operations are more efficient than
i = i.successor(). The one that seems particularly at issue is the
instance in the implementation of partition(), which I changed to
use i._successorInPlace(). If other instances lead to a perf issue,
they can be changed to use that as well.
Revert "For unsafeReferenceCast rely on static verifier checks."
This reverts commit r32796.
This reverts commit r32795.
They very likely broke a buildbot.
Swift SVN r32813
unsafeBitCast should only be used when we actually need to lie to the type system (as opposed to just having an unchecked downcast).
Theses are the places where unsafeReferenceCast makes sense:
(In general it makes sense whenever the source & dest are class or class existential types)
- ArrayBuffer.getElement.
The deferred downcast case cannot be benchmarked. It is never on the critical path.
The ObjC array case cannot conceivably matter either, however, it is touched by
DollarChain, JSONHelperDeserialize, and StrSplitter.
These benchmarks do not regress at -O.
- arrayForceCast
No regressions at -O based on microbenchmarks.
None of these remaining cases affect PerfTestSuite at -O:
- General ObjC bridging
- Set/Dictionary bridging
- String bridging
- AutoreleasingUnsafeMutablePointer
These are confirmed speedups but I did not investigate the cause:
|.Chars...................|.32.1%.|
|.Sim2DArray..............|.15.4%.|
|.Calculator..............|.13.0%.|
|.RecursiveOwnedParameter.|..7.9%.|
Swift SVN r32796
