conversions that reverse an implicit conversion done to align
foreign declarations with their imported types.
For example, consider an Objective-C method that returns an NSString*:
- (nonnull NSString*) foo;
This will be imported into Swift as a method returning a String:
func foo() -> String
A call to this method will implicitly convert the result to String
behind the scenes. If the user then casts the result back to NSString*,
that would normally be compiled as an additional conversion. The
compiler cannot simply eliminate the conversion because that is not
necessarily semantically equivalent.
This peephole recognizes as-casts that immediately reverse a bridging
conversion as a special case and gives them special power to eliminate
both conversions. For example, 'foo() as NSString' will simply return
the original return value. In addition to call results, this also
applies to call arguments, property accesses, and subscript accesses.
ground work for the syntactic bridging peephole.
- Pass source and dest formal types to the bridging routines in addition
to the dest lowered type. The dest lowered type is still necessary
in order to handle non-standard abstraction patterns for the dest type.
- Change bridging abstraction patterns to store bridged formal types
instead of the formal type.
- Improve how SIL type lowering deals with import-as-member patterns.
- Fix some AST bugs where inadequate information was being stored in
various expressions.
- Introduce the idea of a converting SGFContext and use it to regularize
the existing id-as-Any conversion peephole.
- Improve various places in SILGen to emit directly into contexts.
through a few places.
This patch should be NFC for existing patterns, but it's preparing for
using SILGen's built-in bridging capabilities for more things.
SILBuilder now tracks data dependencies between instructions
that open existentials and uses of the opened type, so
SILGen's mechanism for this is no longer needed.
In particular, this simplifies ArchetypeCalleeBuilder.
NormalProtocolConformance has the only correct implementation of this
functionality. Instead, providing a safer getWitnessDecl() that
doesn't promise substitutions that are incorrect (and not actually
used by any clients).
The new API is broken. Popping a generic context frees all
dependent type lowerings, so this function returns a pointer
to freed memory.
This reverts commit 24dfae0716.
This commit does a few things:
1. It uses SwitchEnumBuilder so we are not re-inventing any wheels.
2. Instead of hacking around not putting in a destroy for .None on the fail
pass, just *do the right thing* and recognize that we have a binary case enum
and in such a case, just emit code for the other case rather than use a default
case (meaning no cleanup on .none).
rdar://31145255
Change emitApplyOfLibraryIntrinsic() to take a SubstitutionMap,
and use the correct abstractions to build the map.
This gets rid of the last remaining uses of gatherAllSubstitutions()
in SIL.
This is the first in a series of changes to make SILGen always emit switch_enums
such that payloads are always passed as an arguments to the destination blocks.
This is important since switch_enum today in SILGen is modeled as a consuming
operation. Thus if we follow the model today where we reuse in the destination
blocks the switched upon value, we have created either a use after free or a
double consuming (depending on how the value is used).
There is no reason why we should use a default case here for these optional enums.
rdar://29791263
There are many cases where getBufferForExpr and manageBufferForExpr occur right
next to each other. The closure based API expresses this pattern in a more
convenient manner where the user can express his/her intent with one action
instead of two. In these cases, the split is messy and not necessary.
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.
As per John, WritebackScope was always an unfortunate name. Generally these
scopes are meant for formal evaluations of inout parameters. The cases that I am
interested in generalizing them to be used for are borrows of the base of a
class that will then be used as an lvalue.
This also eliminates the out of line vector of lvalue writebacks.
rdar://29791263
SubstitutionList is going to be a more compact representation of
a SubstitutionMap, suitable for inline allocation inside another
object.
For now, it's just a typedef for ArrayRef<Substitution>.
Most of this involved sprinkling ValueOwnershipKind::Owned in many places. In
some of these places, I am sure I was too cavalier and I expect some of them to
be trivial. The verifier will help me to track those down.
On the other hand, I do expect there to be some places where we are willing to
accept guaranteed+trivial or owned+trivial. In those cases, I am going to
provide an aggregate ValueOwnershipKind that will then tell SILArgument that it
should disambiguate using the type. This will eliminate the ackwardness from
such code.
I am going to use a verifier to fix such cases.
This commit also begins the serialization of ValueOwnershipKind of arguments,
but does not implement parsing of value ownership kinds. That and undef are the
last places that we still use ValueOwnershipKind::Any.
rdar://29791263
We preserve the current behavior of assuming Any ownership always and use
default arguments to hide this change most of the time. There are asserts now in
the SILBasicBlock::{create,replace,insert}{PHI,Function}Argument to ensure that
the people can only create SILFunctionArguments in entry blocks and
SILPHIArguments in non-entry blocks. This will ensure that the code in tree
maintains the API distinction even if we are not using the full distinction in
between the two.
Once the verifier is finished being upstreamed, I am going to audit the
createPHIArgument cases for the proper ownership. This is b/c I will be able to
use the verifier to properly debug the code. At that point, I will also start
serializing/printing/parsing the ownershipkind of SILPHIArguments, but lets take
things one step at a time and move incrementally.
In the process, I also discovered a CSE bug. I am not sure how it ever worked.
Basically we replace an argument with a new argument type but return the uses of
the old argument to refer to the old argument instead of a new argument.
rdar://29671437
