Make getDesugaredType() as fast as possible for now. With the old way:
1) Switching over the sugared types turned into a frequently
mispredicted branch because the sugar in the type system is random
as far as the processor is concerned.
2) Storing the underlying/singlely-desugared type at different offsets
in memory adds more code bloat and misprediction.
Short of a major redesign to avoid pointer chasing, this is probably as
fast as the method will get.
1) Remove SWIFT_INLINE_BITS boilerplate. Now that we're not using anonymous/transparent unions, we don't need the
SWIFT_BITFIELD_BITS macro.
2) Refine the the bitfield size check to better support templated bitfields.
3) Refine the SIL templated bitfields to not be prematurely "full".
Swift class metadata has a bit to distinguish it from non-Swift Objective-C
classes. The stable ABI will use a different bit so that stable Swift and
pre-stable Swift can be distinguished from each other.
No bits are actually changed yet. Enabling the new bit needs to wait for
other coordination such as libobjc.
rdar://35767811
The original hope was we could make these heuristics really good, but
since that is not currently in sight (and may never be), we want to be
able to turn them off. For now, just plumb through an internal flag to
control the behaviour. A future change will customize the behaviour in
SourceKit.
rdar://31113161
Also, give each class hierarchy at least 8 bits for the 'Kind' field.
In practice, no class hierarchy has more than 256 nodes, so this
optimizees code generation to make isa/dyn_cast faster.
Inline bitfields are a common design pattern in LLVM and derived
projects, but the associated boilerplate can be demotivating and
brittle. This new header makes it easier to define and use inline
bitfields in Swift.
This also reorders some fields for better code generation.
Conditional conformances aren't quite ready yet for Swift 4.1, so
introduce the flag `-enable-experimental-conditional-conformances` to
enable conditional conformaces, and an error when one declares a
conditional conformance without specifying the flag.
Add this flag when building the standard library (which will vend
conditional conformances) and to all of the tests that need it.
Fixes rdar://problem/35728337.
This commit is mostly refactoring.
*) Introduce a new OptimizationMode enum and use that in SILOptions and IRGenOptions
*) Allow the optimization mode also be specified for specific SILFunctions. This is not used in this commit yet and thus still a NFC.
Also, fixes a minor bug: we didn’t run mandatory IRGen passes for functions with @_semantics("optimize.sil.never")
