Removes the underscored prefixes from the @_section and @_used attributes, making them public as @section and @used respectively. The SymbolLinkageMarkers experimental feature has been removed as these attributes are now part of the standard language. Implemented expression syntactic checking rules per SE-0492.
Major parts:
- Renamed @_section to @section and @_used to @used
- Removed the SymbolLinkageMarkers experimental feature
- Added parsing support for the old underscored names with deprecation warnings
- Updated all tests and examples to use the new attribute names
- Added syntactic validation for @section to align with SE-0492 (reusing the legality checker by @artemcm)
- Changed @DebugDescription macro to explicitly use a tuple type instead of type inferring it, to comply with the expression syntax rules
- Added a testcase for the various allowed and disallowed syntactic forms, `test/ConstValues/SectionSyntactic.swift`.
Was mistakenly counting a 'store' as
a copying instruction, when it's only a
consuming one.
SILGen was not handling lvalues that are
addresses for loadable types correctly,
when emitting a CopyExpr in ManualOwnership.
This attribute forces programmers to acknowledge every
copy that is required to happen in the body of the
function. Only those copies that make sense according
to Swift's ownership rules should be "required".
The way this is implemented as of now is to flag each
non-explicit copy in a function, coming from SILGen, as
an error through PerformanceDiagnostics.
1. move embedded diagnostics out of the PerformanceDiagnostics pass. It was completely separated from the other logic in this pass, anyway.
2. rewrite it in swift
3. fix several bugs, that means: missed diagnostics, which led to IRGen crashes
* look at all methods in witness tables, including base protocols and associated conformances
* visit all functions in the call tree, including generic functions with class bound generic arguments
* handle all instructions, e.g. concurrency builtins
4. improve error messages by adding meaningful call-site information. For example:
* if the error is in a specialized function, report where the generic function is originally specialized with concrete types
* if the error is in a protocol witness method, report where the existential is created
When performance diagnostics were introduced, typed throws didn't exist
so it was not generally possible to have throws anywhere without
triggering performance diagnostics. As a short term hack, we disabled
checking of `throw` instructions and the basic blocks that terminate
in a `throw`.
Now that typed throws is available and can be used to eliminate
allocations with error handling, remove all of the hacks. We'll now
diagnose attempts to throw or catch existential values (e.g., the `any
Error` used for untyped throws), but typed throws are fine.
MandatoryPerformanceOptimizations already did most of the vtable specialization work.
So it makes sense to remove the VTableSpecializerPass completely and do everything in MandatoryPerformanceOptimizations.
Motivated by need for protocol-based dynamic dispatch, which hasn't been possible in Embedded Swift due to a full ban on existentials. This lifts that restriction but only for class-bound existentials: Class-bound existentials are already (even in desktop Swift) much more lightweight than full existentials, as they don't need type metadata, their containers are typically 2 words only (reference + wtable pointer), don't incur copies (only retains+releases).
Included in this PR:
[x] Non-generic class-bound existentials, executable tests for those.
[x] Extension methods on protocols and using those from a class-bound existential.
[x] RuntimeEffects now differentiate between Existential and ExistentialClassBound.
[x] PerformanceDiagnostics don't flag ExistentialClassBound in Embedded Swift.
[x] WTables are generated in IRGen when needed.
Left for follow-up PRs:
[ ] Generic classes support
Otherwise IRGen would crash.
It needs a bit of work to support alloc_box of generic non-copyable structs/enums with deinit, because we need to specialize the deinit functions, though they are not explicitly referenced in SIL.
Until this is supported, give an error in such cases.
Fixes a compiler crash in IRGen
rdar://130283111
Enable KeyPath/AnyKeyPath/PartialKeyPath/WritableKeyPath in Embedded Swift, but
for compile-time use only:
- Add keypath optimizations into the mandatory optimizations pipeline
- Allow keypath optimizations to look through begin_borrow, to make them work
even in OSSA.
- If a use of a KeyPath doesn't optimize away, diagnose in PerformanceDiagnostics
- Make UnsafePointer.pointer(to:) transparent to allow the keypath optimization
to happen in the callers of UnsafePointer.pointer(to:).
Not de-virtualized value type deinits can require metatype in case the deinit needs to be called via the value witness table.
Usually this does not happen because deinits are mandatory de-virtualized. But it can show up if e.g. wrong build options are used.
rdar://122651706
* Don't exclude code which end up in an infinite loop. rdar://116705459
* Don't exclude error handling code (throw, catch). Errors are existentials and will always allocate. Once we have typed throws it will be possible to do error handling without allocations.
It can be very hard to debug (from a compiler engineers perspective) why the perforamnce diagnostics aren't allowing a certain pattern. Usually this means adding a bunch of random SIL dumps to debug. With these stack traces, you can now just add `-Xllvm -swift-diagnostics-assert-on-error=1` and the stack dumps will do the rest.
Before this change, if a global variable is required to be statically initialized (e.g. due to @_section attribute), we don't allow its type to be a struct, only a scalar type works. This change improves on that by teaching MandatoryPerformanceOptimizations pass to inline struct initializer calls into initializer of globals, as long as they are simple enough so that we can be sure that we don't trigger recursive/infinite inlining.
Attribute @_silgen_name is today only allowed to be used on functions, this change allows usage on globals as well. The motivation for that is to be able to "forward declare" globals just like it's today possible to do with functions (for the cases where it's not practical or convenient to use a bridging header).
Separately, this change also adds a @_silgen_name(raw: ...) syntax, which simply avoids mangling the name (by using the \01 name prefix that LLVM uses). The motivation for that is to be able to reference the "magic Darwin linker symbols" that can be used to look up section bounds (in the current dylib/module) -- those symbols don't use the underscore prefix in their mangled names.
* Look through `begin_borrow` when analyzing closure values
* Treat non-escaping closures as trivial values when passed to a `partial_apply`
rdar://111046264
