When applying a solution to a nil literal of Optional type, we would
build a direct reference to Optional<T>.none instead of leaving the
NilLiteralExpr in place, because this would generate more efficient
SIL that avoided the call to the Optional(nilLiteral: ()) witness.
However, a few places in the type checker build type-checked AST, and
they build NilLiteralExpr directly. Moving the peephole to SILGen's
lowering of NilLiteralExpr allows us to simplify generated SIL even
further by eliding an unnecessary metatype value. Furthermore, it
allows SILGen to accept NilLiteralExprs that do not have a
ConcreteDeclRef set, which makes type-checked AST easier to build.
This is a large patch; I couldn't split it up further while still
keeping things working. There are four things being changed at
once here:
- Places that call SILType::isAddressOnly()/isLoadable() now call
the SILFunction overload and not the SILModule one.
- SILFunction's overloads of getTypeLowering() and getLoweredType()
now pass the function's resilience expansion down, instead of
hardcoding ResilienceExpansion::Minimal.
- Various other places with '// FIXME: Expansion' now use a better
resilience expansion.
- A few tests were updated to reflect SILGen's improved code
generation, and some new tests are added to cover more code paths
that previously were uncovered and only manifested themselves as
standard library build failures while I was working on this change.
Tear out the hacks to pre-substitute opaque types before they enter the SIL type system.
Implement UnderlyingToOpaqueExpr as bitcasting the result of the underlying expression from the
underlying type to the opaque type.
In a few corner cases we built DeclRefExpr and MemberRefExpr
for references to types. These should just be TypeExpr so that
SILGen doesn't have to deal with it.
This also fixes a bug where a protocol typealias with an
unbound generic type could not be accessed properly from
expression context, but that is just so incredibly obscure.
For anything else, we can decompose the argument list on the spot.
Note that builtins that are implemented as EarlyEmitters now take a
the argument list as a PreparedArguments instead of a single Expr.
Since the PreparedArguments can still be a scalar with an
ArgumentShuffleExpr, we have to jump through some hoops to turn
it into a list of argument Exprs. This will all go away soon.
This is equivalent to the trivial case of an ArrayExpr with the
Array.init(arrayLiteral: T...) initializer; it will be used by
CSApply to build vararg arrays.
VarargExpansionExpr shows up in call argument lists in synthesized
initializers and modify accessors when we need to forward arguments
to a call taking varargs.
Previously we would say that the type of VarargExpansionExpr is
$T when its subexpression type is [$T]. matchCallArguments() would
then 'collect' the single VarargExpansionExpr into a variadic
argument list with a single element, and build an ArgumentShuffleExpr
for the argument list.
In turn, SILGen would peephole vararg emission of a variadic
argument list with a single entry that happens to be a
VarargExpansionExpr, by returning the subexpression's value,
which happened to be an array of the right element type,
instead of building a new array containing the elements of the
variadic argument list.
This was all too complicated. Instead, let's say that the type of
a VarargExpansionExpr is [$T], except that when it appears in a
TupleExpr, the variadic bit of the corresponding element is set.
Then, matchCallArguments() needs to support a case where both
the parameter and argument list have a matching vararg element.
In this case, instead of collecting multiple arguments into a
single variadic argument list, we treat the variadic argument like
an ordinary parameter, bypassing construction of the
ArgumentShuffleExpr altogether.
Finally, SILGen now needs to be able to emit a VarargExpansionExpr
in ordinary rvalue position, since it now appears as a child of a
TupleExpr; it can do this by simply emitting the sub-expression
to produce an array value.
TupleShuffleExpr could not express the full range of tuple conversions that
were accepted by the constraint solver; in particular, while it could re-order
elements or introduce and eliminate labels, it could not convert the tuple
element types to their supertypes.
This was the source of the annoying "cannot express tuple conversion"
diagnostic.
Replace TupleShuffleExpr with DestructureTupleExpr, which evaluates a
source expression of tuple type and binds its elements to OpaqueValueExprs.
The DestructureTupleExpr's result expression can then produce an arbitrary
value written in terms of these OpaqueValueExprs, as long as each
OpaqueValueExpr is used exactly once.
This is sufficient to express conversions such as (Int, Float) => (Int?, Any),
as well as the various cases that were already supported, such as
(x: Int, y: Float) => (y: Float, x: Int).
https://bugs.swift.org/browse/SR-2672, rdar://problem/12340004
OpaqueValueState used to store a SILValue, so back then the IsConsumable flag
was meaningful. But now we can just check if the ManagedValue has a cleanup
or not.
Also, we were passing around an opened ArchetypeType for no good reason.
Before extending TupleShuffleExpr to represent all tuple
conversions allowed by the constraint solver, remove the
parts of TupleShuffleExpr that are no longer needed; this is
support for default arguments, varargs, and scalar-to-tuple and
tuple-to-scalar conversions.
Right now we use TupleShuffleExpr for two completely different things:
- Tuple conversions, where elements can be re-ordered and labels can be
introduced/eliminated
- Complex argument lists, involving default arguments or varargs
The first case does not allow default arguments or varargs, and the
second case does not allow re-ordering or introduction/elimination
of labels. Furthermore, the first case has a representation limitation
that prevents us from expressing tuple conversions that change the
type of tuple elements.
For all these reasons, it is better if we use two separate Expr kinds
for these purposes. For now, just make an identical copy of
TupleShuffleExpr and call it ArgumentShuffleExpr. In CSApply, use
ArgumentShuffleExpr when forming the arguments to a call, and keep
using TupleShuffleExpr for tuple conversions. Each usage of
TupleShuffleExpr has been audited to see if it should instead look at
ArgumentShuffleExpr.
In sequent commits I plan on redesigning TupleShuffleExpr to correctly
represent all tuple conversions without any unnecessary baggage.
Longer term, we actually want to change the representation of CallExpr
to directly store an argument list; then instead of a single child
expression that must be a ParenExpr, TupleExpr or ArgumentShuffleExpr,
all CallExprs will have a uniform representation and ArgumentShuffleExpr
will go away altogether. This should reduce memory usage and radically
simplify parts of SILGen.
The ownership kind is Any for trivial types, or Owned otherwise, but
whether a type is trivial or not will soon depend on the resilience
expansion.
This means that a SILModule now uniques two SILUndefs per type instead
of one, and serialization uses two distinct sentinel IDs for this
purpose as well.
For now, the resilience expansion is not actually used here, so this
change is NFC, other than changing the module format.
Each call site will soon have to think about passing in the right expansion
instead of just assuming the default will be OK. But there are now only a
few call sites left, because most have been refactored to use convenience
APIs that pass in the right resilience expansion already.
For context, String, Nil, Bool, and Int already behave this way.
Note: Swift can compile against 80 or 64 bit floats as the builtin
literal type. Thus, it was necessary to capture this bit somehow in the
FloatLiteralExpr. This was done as another Type field capturing this
info.
For context, String, Nil, and Bool already behave this way.
Note: Before it used to construct (call, ... (integer_literal)), and the
call would be made explicit / implicit based on if you did eg: Int(3) or
just 3. This however did not translate to the new world so this PR adds
a IsExplicitConversion bit to NumberLiteralExpr. Some side results of
all this are that some warnings changed a little and some instructions are
emitted in a different order.
Instead of constructing calls to ExpressibleByBooleanLiteral.init(booleanLiteral: ...) in CSApply.cpp, just
annotate BooleanLiteralExpr with the selected constructor and do the actual construction during SILGen.
For context, StringLiteralExpr and NilLiteralExpr already behave this way.
Instead of constructing calls to
ExpressibleByNilLiteral.init(nilLiteral: ()) in CSApply.cpp, just
annotate NilLiteralExpr with the selected construtor and do the actual
construction during SILGen.
For context, StringLiteralExpr already behaves this way.
We use TupleShuffleExpr in RValue position for enum element payloads, and
it can happen that the source is a scalar if you're calling the enum element
constructor with a trailing closure.
This reverts commit 7960660b7e.
Fixes <https://bugs.swift.org/browse/SR-9675>.
We already assert that each element of the tuple is an lvalue;
asserting that the tuple itself has an lvalue or is Void is
incorrect because the tuple might have zero non-tuple elements
recursively but itself not be Void, eg ((), ()).
Fixes <https://bugs.swift.org/browse/SR-5919>.
