Take a seat and pour yourself a beer because this is
going to get pretty intense.
Recall that class methods that return 'Self', have a
'self' type of @dynamic_self X or @dynamic_self X.Type,
for some class X, based on if the method is an instance
method or a static method.
The instance type of a metatype is not lowered, and we
preserve DynamicSelfType there. This is required for
correct behavior with the SIL optimizer.
For example if you specialize a function that contains a
'metatype $((T) -> Int, T).Type' SIL instruction or
some other metatype of a structural type containing a
generic parameter, we might end up with something like
'metatype $((@dynamic_self X) -> Int, X).Type'
after substitution, for some class 'X'. Note that the
second occurrence of 'X', is in "lowered position" so
the @dynamic_self did, indeed, get stripped away.
So while *values* of @dynamic_self type don't need to
carry the fact that they're @dynamic_self at the SIL
level, because Sema has inserted all the right casts.
Metatypes do though, because when lowering the 'metatype'
instruction, IRGen has to know to emit the type metadata
from the method's 'self' parameter, and not the static
metadata for the exact class type.
Essentially, 'metatype @dynamic_self X.Type' is
the same as 'value_metatype %self : X.Type', except that
the @dynamic_self type can appear inside other structural
types also, which is something we cannot write in the
AST.
This is all well and good, but when lowering a
SILFunctionType we erase @dynamic_self from the 'self'
parameter type because when you *call* such a function
from another function, you are not necessarily calling
it on your own 'self' value. And if you are, Sema
already emitted the right unchecked downcast there to
turn the result into the right type.
The problem is that the type of an argument (the value
"inside" the function) used to always be identical to
the type of the parameter (the type from "outside" the
function, in the SILFunctionType). Of course this
assumption is no longer correct for static methods,
where the 'self' argument should really have type
@dynamic_self X.Type, not X.Type.
A further complication is closure captures, whose types
can also contain @dynamic_self inside metatypes in other
structural types. We used to erase @dynamic_self from
these.
Both of these are wrong, because if you call a generic
function <T> (T.Type) -> () with a T := @dynamic_self X
substitution (recall that substitutions are written in
terms of AST types and not lowered types) and pass in
the 'self' argument, we would pass in a value of type
X.Type and not @dynamic_self X.Type.
There were similar issues with captures, with
additional complications from nested closures.
Fix all this by having SILGenProlog emit a downcast
to turn the X.Type argument into a value of type
@dynamic_self X.Type, and tweak capture lowering to
not erase @dynamic_self from capture types.
This fixes several cases that used to fail with
asserts in SILGenApply or the SIL verifier, in particular
the example outlined in <rdar://problem/31226650>,
where we would crash when calling a protocol extension
method from a static class method (oops!).
If you got this far and still follow along,
congratulations, you now know more about DynamicSelfType
than I do.
Instead of appending a character for each substitution, we now prefix the substitution with the repeat count, e.g.
AbbbbB -> A5B
The same is done for known-type substitutions, e.g.
SiSiSi -> S3i
This significantly shrinks mangled names which contain large lists of the same type, like
func foo(_ x: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int))
rdar://problem/30707433
We have a quirk where TypeBase::getSuperclass() on DynamicSelfType
returns the underlying class type, and not the superclass of the
underlying class type. As a result, we would emit a SuperRefExpr
whose type was the type of 'self' and not the type of 'super'.
Fixes <rdar://problem/30853768>.
Once we move to a copy-on-write implementation of existential value buffers we
can no longer consume or destroy values of an opened existential unless the
buffer is uniquely owned.
Therefore we need to track the allowed operation on opened values.
Add qualifiers "mutable_access" and "immutable_access" to open_existential_addr
instructions to indicate the allowed access to the opened value.
Once we move to a copy-on-write implementation, an "open_existential_addr
mutable_access" instruction will ensure unique ownership of the value buffer.
Textual SIL was sometimes ambiguous when SILDeclRefs were used, because the textual representation of SILDeclRefs was the same for functions that have the same name, but different signatures.
Textual SIL was sometimes ambiguous when SILDeclRefs were used, because the textual representation of SILDeclRefs was the same for functions that have the same name, but different signatures.
A change was recently made to canonicalize replacement types in
GenericSignature::getSubstitutions().
This resulted in ParenType being stripped off, which triggered
the 'tuple splat' diagnostic on code that was accepted in Swift 3.0.
I believe this canonicalization step is unnecessary; we
canonicalize using a brand-new ArchetypeBuilder that has no
generic signature added to it, so this is just equivalent to a
call to getCanonicalType().
Also adding the generic signature in question to the builder is
not the right answer either; the replacement types might be
written in terms of a different generic signature, or possibly
in terms of archetypes.
Taking this out seems to have no effect except changing a few
SIL dumps to contain sugared types, which should be harmless.
Part of fixing <rdar://problem/29739905>.
When enumerating requirements, always use the archetype anchors to
express requirements. Unlike "representatives", which are simply there
to maintain the union-find data structure used to track equivalence
classes of potential archetypes, archetype anchors are the
ABI-stable canonical types within a fully-formed generic signature.
The test case churn comes from two places. First, while
representatives are *often* the same as the archetype anchors, they
aren't *always* the same. Where they differ, we'll see a change in
both the printed generic signature and, therefore, it's
mangling.
Additionally, requirement inference now takes much greater
care to make sure that the first types in the requirement follow
archetype anchor ordering, so actual conformance requirements occur in
the requirement list at the archetype anchor---not at the first type
that is equivalent to the anchor---which permits the simplification in
IRGen's emission of polymorphic arguments.
If a generic parameter was substituted for Self, we have to be careful
to not erase Self.Type down to a concrete metatype.
Also, teach the devirtualizer that a metatype of Self type does not
have an exact static type.
Previously, SIL type lowering would assume a MetatypeType was
completely lowered if it had a representation, but this is not
quite right; after substitution, we can have a MetatypeType
whose instance type is a DynamicSelfType. Strip these away more
eagerly, since they show up in SILType::subst(), where we first
substitute AST-level generic parameters, and then lower the
result to get the final SIL type.
Fixes <https://bugs.swift.org/browse/SR-2733>.
Officially kick SILBoxType over to be "nominal" in its layout, with generic layouts structurally parameterized only by formal types. Change SIL to lower a capture to a nongeneric box when possible, or a box capturing the enclosing generic context when necessary.
Use a syntax that declares the layout's generic parameters and fields,
followed by the generic arguments to apply to the layout:
{ var Int, let String } // A concrete box layout with a mutable Int
// and immutable String field
<T, U> { var T, let U } <Int, String> // A generic box layout,
// applied to Int and String
// arguments
This ensures that ownership is properly propagated forward through the use-def
graph.
This was the work that was stymied by issues relating to SILBuilder performing
local ARC dataflow. I ripped out that local dataflow in 6f4e2ab and added a
cheap ARC guaranteed dataflow pass that performs the same optimization.
Also in the process of doing this work, I found that there were many SILGen
tests that were either pattern matching in the wrong functions or had wrong
CHECK lines (for instance CHECK_NEXT). I fixed all of these issues and also
expanded many of the tests so that they verify ownership. The only work I left
for a future PR is that there are certain places in tests where we are using the
projection from an original value, instead of a copy. I marked those with a
message SEMANTIC ARC TODO so that they are easy to find.
rdar://28685236
When DynamicSelfType occurs outside of a class body (for example,
inside of a SIL function), it is not enough to simply utter 'Self',
because then we lose the underlying type.
Instead, print it out as '@dynamic_self Foo', where 'Foo' is the
underlying class type or archetype, and add parser support for
the same.
Fixes <rdar://problem/27735857>.
If a closure captures the dynamic 'Self' type, but no value of type 'Self'
(for example, it is possible to have a weak capture of 'self'; if the weak
reference becomes nil, there's no way for the closure to get the dynamic
'Self' type from the value).
In this case, add a hidden argument of type $Self.Type, and pass in the
Self metatype.
Fixes <https://bugs.swift.org/browse/SR-1558> / <rdar://problem/22299905>.
Similarly to how we've always handled parameter types, we
now recursively expand tuples in result types and separately
determine a result convention for each result.
The most important code-generation change here is that
indirect results are now returned separately from each
other and from any direct results. It is generally far
better, when receiving an indirect result, to receive it
as an independent result; the caller is much more likely
to be able to directly receive the result in the address
they want to initialize, rather than having to receive it
in temporary memory and then copy parts of it into the
target.
The most important conceptual change here that clients and
producers of SIL must be aware of is the new distinction
between a SILFunctionType's *parameters* and its *argument
list*. The former is just the formal parameters, derived
purely from the parameter types of the original function;
indirect results are no longer in this list. The latter
includes the indirect result arguments; as always, all
the indirect results strictly precede the parameters.
Apply instructions and entry block arguments follow the
argument list, not the parameter list.
A relatively minor change is that there can now be multiple
direct results, each with its own result convention.
This is a minor change because I've chosen to leave
return instructions as taking a single operand and
apply instructions as producing a single result; when
the type describes multiple results, they are implicitly
bound up in a tuple. It might make sense to split these
up and allow e.g. return instructions to take a list
of operands; however, it's not clear what to do on the
caller side, and this would be a major change that can
be separated out from this already over-large patch.
Unsurprisingly, the most invasive changes here are in
SILGen; this requires substantial reworking of both call
emission and reabstraction. It also proved important
to switch several SILGen operations over to work with
RValue instead of ManagedValue, since otherwise they
would be forced to spuriously "implode" buffers.
The SIL parser used PolymorphicFunctionType in two places:
- Internals of SILFunctionType parsing
- Overload selection for class_method / super_method / dynamic_method
instructions
It is better to have Sema construct GenericFunctionType directly
in SIL mode. In particular, the overload selection logic is simpler
now, since it does not have to deal with the fact that
PolymorphicFunctionTypes do not canonicalize.
Mostly NFC, except the SIL printer output is a bit different; for a
generic method on a generic type, the type parameters all come first,
like ``<T><U> G<T> -> (U) -> ()'' -vs- ``<T> G<T> -> <U> (U) -> ()''.
Also, generic constraints look different, instead of ``<`Self` : P>``
we now have ``<Self where Self : P>''.
This patch has two consequences that will become important later:
- While code that constructs PolymorphicFunctionType still exists in
Sema, the SIL parser was the last major component that *consumed*
PolymorphicFunctionType.
- Everywhere we set SILFunction::ContextGenericParams, we now have
a well-formed context GenericSignature available, allowing
ContextGenericParams to be replaced by a GenericSignature
eventually.
And use project_box to get to the address value.
SILGen now generates a project_box for each alloc_box.
And IRGen re-uses the address value from the alloc_box if the operand of project_box is an alloc_box.
This lets the generated code be the same as before.
Other than that most changes of this (quite large) commit are straightforward.
Having a separate address and container value returned from alloc_stack is not really needed in SIL.
Even if they differ we have both addresses available during IRGen, because a dealloc_stack is always dominated by the corresponding alloc_stack in the same function.
Although this commit quite large, most changes are trivial. The largest non-trivial change is in IRGenSIL.
This commit is a NFC regarding the generated code. Even the generated SIL is the same (except removed #0, #1 and @local_storage).
Parameters (to methods, initializers, accessors, subscripts, etc) have always been represented
as Pattern's (of a particular sort), stemming from an early design direction that was abandoned.
Being built on top of patterns leads to patterns being overly complicated (e.g. tuple patterns
have to have varargs and default parameters) and make working on parameter lists complicated
and error prone. This might have been ok in 2015, but there is no way we can live like this in
2016.
Instead of using Patterns, carve out a new ParameterList and Parameter type to represent all the
parameter specific stuff. This simplifies many things and allows a lot of simplifications.
Unfortunately, I wasn't able to do this very incrementally, so this is a huge patch. The good
news is that it erases a ton of code, and the technical debt that went with it. Ignoring test
suite changes, we have:
77 files changed, 2359 insertions(+), 3221 deletions(-)
This patch also makes a bunch of wierd things dead, but I'll sweep those out in follow-on
patches.
Fixes <rdar://problem/22846558> No code completions in Foo( when Foo has error type
Fixes <rdar://problem/24026538> Slight regression in generated header, which I filed to go with 3a23d75.
Fixes an overloading bug involving default arguments and curried functions (see the diff to
Constraints/diagnostics.swift, which we now correctly accept).
Fixes cases where problems with parameters would get emitted multiple times, e.g. in the
test/Parse/subscripting.swift testcase.
The source range for ParamDecl now includes its type, which permutes some of the IDE / SourceModel tests
(for the better, I think).
Eliminates the bogus "type annotation missing in pattern" error message when a type isn't
specified for a parameter (see test/decl/func/functions.swift).
This now consistently parenthesizes argument lists in function types, which leads to many diffs in the
SILGen tests among others.
This does break the "sibling indentation" test in SourceKit/CodeFormat/indent-sibling.swift, and
I haven't been able to figure it out. Given that this is experimental functionality anyway,
I'm just XFAILing the test for now. i'll look at it separately from this mongo diff.
SILPrinter was printing uses for all SIL values, except for SIL basic blocks arguments. Fill the gap and print uses for BB arguments as well. This makes reading and analyzing SIL easier.
Basic blocks may have multiple arguments, therefore print uses of each BB argument on separate lines - one line per BB argument.
The comment containing information about uses of a BB argument is printed on the line just above the basic block name, following the approach used for function_ref and other kinds of instructions, which have additional information printed on the line above the actual instruction.
The output now looks like:
// %0 // user: %3
// %1 // user: %9
bb0(%0 : $Int32, %1 : $UnsafeMutablePointer<UnsafeMutablePointer<Int8>>):
rdar://23336589
And include some supplementary mangling changes:
- Give the first generic param (depth=0, index=0) a single character mangling. Even after removing the self type from method declaration types, 'Self' still shows up very frequently in protocol requirement signatures.
- Fix the mangling of generic parameter counts to elide the count when there's only one parameter at the starting depth of the mangling.
Together these carve another 154KB out of a debug standard library. There's some awkwardness in demangled strings that I'll clean up in subsequent commits; since decl types now only mangle the number of generic params at their own depth, it's context-dependent what depths those represent, which we get wrong now. Currying markers are also wrong, but since free function currying is going away, we can mangle the partial application thunks in different ways.
Swift SVN r32896
Canonical dependent member types are always based from a generic parameter, so we can use a more optimal mangling that assumes this. We can also introduce substitutions for AssociatedTypeDecls, and when a generic parameter in a signature is constrained by a single protocol, we can leave that protocol qualification out of the unsubstituted associated type mangling. These optimizations together shrink the standard library by 117KB, and bring the length of the longest Swift symbol in the stdlib down from 578 to 334 characters, shorter than the longest C++ symbol in the stdlib.
Swift SVN r32786
This makes it clearer that expressions like "foo.myType.init()" are creating new objects, instead of invoking a weird-looking method. The last part of rdar://problem/21375845.
Swift SVN r29375
to not drop optionals in memory all the time. We now generate a lot better code
for them in many cases. This makes generated SIL more readable and should help
-O0 perf.
This is progress towards <rdar://problem/20642198> SILGen shouldn't be dropping optionals into memory all the time
Swift SVN r28102
registers instead of eagerly dumping them in memory and operating on
them by-address. This avoids a lot of temporaries and traffic to
manipulate them.
As part of this, add some new SGF::getOptionalNoneValue/getOptionalSomeValue
helper methods for forming loading optional values.
Many thanks to JoeG for helping with the abstraction difference change in
getOptionalSomeValue.
Swift SVN r27537
The only caveat is that:
1. We do not properly recognize when we have a let binding and we
perform a guaranteed dynamic call. In such a case, we add an extra
retain, release pair around the call. In order to get that case I will
need to refactor some code in Callee. I want to make this change, but
not at the expense of getting the rest of this work in.
2. Some of the protocol witness thunks generated have unnecessary
retains or releases in a similar manner.
But this is a good first step.
I am going to send a large follow up email with all of the relevant results, so
I can let the bots chew on this a little bit.
rdar://19933044
Swift SVN r27241
