We previously shied away from this in order to not /accidentally/
depend on it, but it becomes interesting again with textual
interfaces, which can certainly be read by humans. The cross-file
order is the order of input files, which is at least controllable by
users.
For now, the accessors have been underscored as `_read` and `_modify`.
I'll prepare an evolution proposal for this feature which should allow
us to remove the underscores or, y'know, rename them to `purple` and
`lettuce`.
`_read` accessors do not make any effort yet to avoid copying the
value being yielded. I'll work on it in follow-up patches.
Opaque accesses to properties and subscripts defined with `_modify`
accessors will use an inefficient `materializeForSet` pattern that
materializes the value to a temporary instead of accessing it in-place.
That will be fixed by migrating to `modify` over `materializeForSet`,
which is next up after the `read` optimizations.
SIL ownership verification doesn't pass yet for the test cases here
because of a general fault in SILGen where borrows can outlive their
borrowed value due to being cleaned up on the general cleanup stack
when the borrowed value is cleaned up on the formal-access stack.
Michael, Andy, and I discussed various ways to fix this, but it seems
clear to me that it's not in any way specific to coroutine accesses.
rdar://35399664
The other side of #17404. Since we don't want to generate up front key path metadata for properties/subscripts with no withheld implementation details, the client should generate a key path component that can be used to represent a key path component based on its public interface.
The storage kind has been replaced with three separate "impl kinds",
one for each of the basic access kinds (read, write, and read/write).
This makes it far easier to mix-and-match implementations of different
accessors, as well as subtleties like implementing both a setter
and an independent read/write operation.
AccessStrategy has become a bit more explicit about how exactly the
access should be implemented. For example, the accessor-based kinds
now carry the exact accessor intended to be used. Also, I've shifted
responsibilities slightly between AccessStrategy and AccessSemantics
so that AccessSemantics::Ordinary can be used except in the sorts of
semantic-bypasses that accessor synthesis wants. This requires
knowing the correct DC of the access when computing the access strategy;
the upshot is that SILGenFunction now needs a DC.
Accessor synthesis has been reworked so that only the declarations are
built immediately; body synthesis can be safely delayed out of the main
decl-checking path. This caused a large number of ramifications,
especially for lazy properties, and greatly inflated the size of this
patch. That is... really regrettable. The impetus for changing this
was necessity: I needed to rework accessor synthesis to end its reliance
on distinctions like Stored vs. StoredWithTrivialAccessors, and those
fixes were exposing serious re-entrancy problems, and fixing that... well.
Breaking the fixes apart at this point would be a serious endeavor.
We sometimes serialized the “isObjC” state, and sometimes not. When we did serialize it,
we rarely used the bit for anything. Serialize it for all declarations where it makes
sense, and consistently call setIsObjC() with the deserialized value.
The major important thing here is that by using copy_unowned_value we can
guarantee that the non-ownership SIL ARC optimizer will treat the release
associated with the strong_retain_unowned as on a distinc rc-identity from its
argument. As an example of this problem consider the following SILGen like
output:
----
%1 = copy_value %0 : $Builtin.NativeObject
%2 = ref_to_unowned %1
%3 = copy_unowned_value %2
destroy_value %1
...
destroy_value %3
----
In this case, we are converting a strong reference to an unowned value and then
lifetime extending the value past the original value. After eliminating
ownership this lowers to:
----
strong_retain %0 : $Builtin.NativeObject
%1 = ref_to_unowned %0
strong_retain_unowned %1
strong_release %0
...
strong_release %0
----
From an RC identity perspective, we have now blurred the lines in between %3 and
%1 in the previous example. This can then result in the following miscompile:
----
%1 = ref_to_unowned %0
strong_retain_unowned %1
...
strong_release %0
----
In this case, it is possible that we created a lifetime gap that will then cause
strong_retain_unowned to assert. By not lowering copy_unowned_value throughout
the SIL pipeline, we instead get this after lowering:
----
strong_retain %0 : $Builtin.NativeObject
%1 = ref_to_unowned %0
%2 = copy_unowned_value %1
strong_release %0
...
strong_release %2
----
And we do not miscompile since we preserved the high level rc identity
pairing.
There shouldn't be any performance impact since we do not really optimize
strong_retain_unowned at the SIL level. I went through all of the places that
strong_retain_unowned was referenced and added appropriate handling for
copy_unowned_value.
rdar://41328987
**NOTE** I am going to remove strong_retain_unowned in a forthcoming commit. I
just want something more minimal for cherry-picking purposes.
Cross-references are identified by their containing module, with the
assumption that two modules will never have the same name. However, an
overlay has the same name as its underlying Clang module, which means
that there can be two declarations with the same name, the same type,
and the same module name. This is the underlying cause of the
'UIEdgeInsetsZero' problem, but it also affects the CloudKit overlay.
By tracking a bit that just says "this came from Clang", we're able
to resolve otherwise ambiguous cross-references.
(Why didn't we do it this way all along? Because if a declaration
moves from Clang to Swift or vice versa, that would break the
cross-reference. But that's only interesting if the swiftmodule format
is meant to be persistent across changing dependencies, and it looks
like we're moving away from that anyway. It's also a little weird for
SerializedModuleLoader to have special cases for Clang, but this isn't
the first.)
Note that I'm not reverting the UIEdgeInsetsZero workaround here; the
end state will have that coming just from UIKit as originally
described.
rdar://problem/40839486
Introduce some metaprogramming of accessors and generally prepare
for storing less-structured accessor lists.
NFC except for a change to the serialization format.
This flag supports promoting KeyPath access violations to an error in
Swift 4+, while building the standard library in Swift 3 mode. This is
only necessary as long as the standard library continues to build in
Swift 3 mode. Once the standard library build migrates, it can all be
ripped out.
<rdar://problem/40115738> [Exclusivity] Enforce Keypath access as an error, not a warning in 4.2.
This reverts commit bb16ee049d,
reversing changes made to a8d831f5f5.
It's not sufficient to solve the problem, and the choices were to do
something more complicated, or just take a simple brute force
approach. We're going with the latter.
Mandatory pass will clean it up and replace it by a copy_block and
is_escaping/cond_fail/release combination on the %closure in follow-up
patches.
The instruction marks the dependence of a block on a closure that is
used as an 'withoutActuallyEscaping' sentinel.
rdar://39682865
Convert NameAliasType’s internal representation from tail-allocating an
array of Substitutions (to be treated as a SubstitutionList) to store a
single SubstitutionMap. Serialize using that SubstitutionMap.
Allow substitution maps to be serialized directly (via an ID), writing out
the replacement types and conformances as appropriate. This is a more
efficient form of serialization than the current SubstitutionList approach,
because it maintains uniqueness of substitution maps within a module file,
and is a step toward eliminating SubstitutionList entirely.
Add serialization layouts for rare instructions that take extra attributes. We
can continue adding bits to these layout without affecting the layout of the
vast majority of instructions.
We still use the old layout for NameAliasType for builtin types, so
rename the Layout struct and corresponding code to describe its new
(more restricted) purpose.
Introduce a new Type node, BoundNameAliasType, which describes a
reference to a typealias that requires substitutions to produce the
underlying type. This new type node is used both for references to
generic typealiases and for references to (non-generic) typealiases
that occur within generic contexts, e.g., Array<Int>.Element.
At present, the new type node is mainly useful in preserving type
sugar for diagnostics purposes, as well as being reflected in other
tools (indexing, code completion, etc.). The intent is to completely
replace NameAliasType in the future.
We have a predicate in ClassDecl, 'inheritsSuperclassInitializers',
that is used in a few places to decide if we need to do lookups into a
superclass to find all relevant initializers. That's useful, but the
actual work being computed in that function is almost identical to the
work done in figuring out whether the class has provided all its
superclass's /required/ initializers, which is part of the type
checker operation 'resolveImplicitConstructors'. Furthermore,
'inheritsSuperclassInitializers' is /already/ calling
'resolveImplicitConstructors' because those implicit constructors
might affect the result.
Simplify this whole mess and prevent further inconsistencies like the
previous commit by just making 'resolveImplicitConstructors' decide
whether superclass convenience initializers are inherited. It does
make that function more complicated, but with the benefit of not
having duplication anymore.
No intended user-visible change, except that this bit is now
serialized instead of being recomputed, which means the module format
changed.
This is mostly intended to be used for testing at this point; in the
long run, we want to be using availability information to decide
whether to weak-link something or not. You'll notice a bunch of FIXMEs
in the test case that we may not need now, but will probably need to
handle in the future.
Groundwork for doing backward-deployment execution tests.
We can encounter these when the compiler modifies an inlinable
function to break apart a struct and the struct uses a private
type for one of its fields. It's questionable whether we /should/
handle this, but meanwhile this /is/ a non-intrusive fix that
preserves the performance of non-resilient libraries.
(That is, it appears this worked in Swift 4.0, though perhaps
not all of the same optimizations kicked in.)
https://bugs.swift.org/browse/SR-6874
@noescape function types will eventually be trivial. A
convert_escape_to_noescape instruction does not take ownership of its
operand. It is a projection to the trivial value carried by the closure
-- both context and implementation function viewed as a trivial value.
A safe SIL program must ensure that the object that the project value is based
on is live beyond the last use of the trivial value. This will be
achieve by means of making the lifetimes dependent.
For example:
%e = partial_apply [callee_guaranteed] %f(%z) : $@convention(thin) (Builtin.Int64) -> ()
%n = convert_escape_to_noescape %e : $@callee_guaranteed () -> () to $@noescape @callee_guaranteed () -> ()
%n2 = mark_dependence %n : $@noescape @callee_guaranteed () -> () on %e : $@callee_guaranteed () -> ()
%f2 = function_ref @use : $@convention(thin) (@noescape @callee_guaranteed () -> ()) -> ()
apply %f2(%n2) : $@convention(thin) (@noescape @callee_guaranteed () -> ()) -> ()
release_value %e : $@callee_guaranteed () -> ()
Note: This is not yet actually used.
Part of:
SR-5441
rdar://36116691
Also remove the decl from the known decls and remove a
bunch of code referencing that decl as well as a bunch of other
random things including deserialization support.
This includes removing some specialized diagnostics code that
matched the identifier ImplicitlyUnwrappedOptional, and tweaking
diagnostics for various modes and various issues.
Fixes most of rdar://problem/37121121, among other things.
...rather than the ad hoc CustomTypeNameManglingAttr I was using
before. As John pointed out, the AST should be semantic wherever
possible.
We may someday want to get out of this being an attribute altogether,
or duplicating information that's available in the original Clang
node, by actually storing a reference to that node somewhere. This is
tricky and mixed up with deciding what hasClangNode() or
getClangDecl() would mean, though, so for now the attribute just
carries the information we need.
When importing a C enum with the ns_error_domain attribute, we
synthesize a struct containing an NSError object to represent errors
in that domain. That synthesized struct should have a mangled name
that ties it to the original C enum, if we want it to be stable, and
now it does.
Before: $SSC7MyErrorV (a normal struct, which is a lie)
After: $SSC11MyErrorCode13ns_error_enumLLV
kind=Global
kind=Structure
kind=Module, text="__C_Synthesized"
kind=PrivateDeclName
kind=Identifier, text="ns_error_enum"
kind=Identifier, text="MyErrorCode"
Using the "private discriminator" feature allows us to pack in extra
information about the declaration without changing the mangling
grammar, and without stepping on anything the importer is using.
More rdar://problem/24688918
This is going to be used for "always emit into client" functions,
such as default argument generators and stored property
initializers.
- In dead function elimination, these functions behave identically to
public functions, serving as "anchors" for the mark-and-sweep
analysis.
- There is no external variant of this linkage, because external
declarations can use HiddenExternal linkage -- the definition should
always be emitted by another translation unit in the same Swift
module.
- When deserialized, they receive shared linkage, because we want the
linker to coalesce multiple copies of the same deserialized
definition if it was deserialized from multiple translation units
in the same Swift module.
- When IRGen emits a definition with this linkage, it receives the
same LLVM-level linkage as a hidden definition, ensuring it does not
have a public entry point.
