Generally avoid casting to a raw pointer unless a raw pointer is needed.
Builtin.castReference is now the canonical way to cast reference types.
Canonical generally = better optimizer. In practice this will reduce to
the same SIL since the stdlib code will be optimized.
There are enough unit tests for unsafeDowncast and Builtin.castReference.
I measured no performance regressions.
Swift SVN r32646
_unsafeCastReference allows casting of any references types, regardless
of whether they are references to objects or class existentials. The
implementation is responsible for converting between representations.
_unsafeCastReference provides a dynamic check to ensure that the source
and dest are both actually references. If not, the implementation will
trap at runtime. Generally, the optimizer can prove that the source
and dest are references, and promote this cast to an
unchecked_ref_cast bitcast. There is no dynamic check that the
references types are compatible.
This differs from unsafeDownCast in two ways:
(1) The source and dest types are not statically typed
AnyObjects. Therefore, unsafeCastReference can be used when the
surrounding code dynamically handles both reference and nonreference
types.
(2) The source and dest also need not dynamically conform to AnyObject.
Either side of the cast may be a class existential. The primary
requirement is that the source and dest refer to the same reference
counted object.
Swift SVN r32588
This avoids unnecessary address-taking. Instead use the builtin that directly
supports unsafe casts. The optimizer now follows clear rules for
Builtin.reinterpretCast (so it's safe to use) and knows how to optimize it.
Swift SVN r32268
Instead of Optional entries use a third bitmap array to mark whether an entry is
valid. This representation saves space (because individual entries don't have a
alignment padding slack) and simplifies ARC's job leading to better performance.
Speedup measured (before/after) at -O:
DictionaryHashableClass`````````3.1
DollarFilter````````````````````1.3
DollarMap```````````````````````1.3
DollarReduce````````````````````1.4
JSONHelperDeserialize```````````1.4
NSDictionaryImplicitConversion``1.4
NSXMLParser`````````````````````1.3
Speedup measured (before/after) at -Onone:
DictOfArraysToArrayOfDicts``````1.3
Dictionary``````````````````````3.5
Dictionary2`````````````````````3.2
Dictionary3`````````````````````3.2
DictionaryHashableClass`````````1.9
DictionaryHashableStruct````````2.4
DictionaryRemove````````````````3.3
DictionarySwap``````````````````2.5
DollarFilter````````````````````1.2
DollarMap```````````````````````1.2
DollarReduce````````````````````1.3
Forest``````````````````````````1.8
Histogram```````````````````````1.6
JSONHelperDeserialize```````````1.6
NSDictionaryImplicitConversion``1.3
Prims```````````````````````````2.9
RGBHistogram````````````````````1.4
rdar://22173734
Swift SVN r32244
Slice types that are RangeReplaceable (like ArraySlice) now slice
themselves in removeFirst(). Previously, these types were picking up
the wrong default implementation, and they were going through
replaceRange(), which caused all indices to be invalidated. The new
implementation preserves all indices.
rdar://22536664
Swift SVN r31918
The extra control-flow seems to inhibit ARC and we end up with an extra
retain-release regressing LevenshteinDistance by 40%.
rdar://22479186
Swift SVN r31588
Revert "Add test cases to exercise the native String vs cocoa buffer String path."
Revert "stdlib: Add back a test I removed"
Revert "stdlib: Fix hasPrefix,hasSuffix tests"
Revert "stdlib: Add documentation for the cached ascii collation tables"
This reverts commit 31493, 31492, 31491, 31490, 31489.
There are linking errors in SwiftExternalProjects (we probably have to link
against libicucore somewhere).
Swift SVN r31543
directly construct a buffer of the right size
This safes a uniqueness check and unecessary code bloat when inlining
reserveCapacity.
rdar://22446738
Swift SVN r31540
