Right now, re-abstraction thunks are set up to convert values
as follows, where L is type lowering:
- OrigToSubst: L(origType, substType) -> L(substType)
- SubstToOrig: L(substType) -> L(origType, substType)
This assumes there's no AST-level type conversion, because
when we visit a type in contravariant position, we flip the
direction of the transform but we're still converting *to*
substType -- which will now equal to the type of the input,
not the type of the expected result!
This caused several problems:
- VTable thunk generation had a bunch of special logic to
compute a substOverrideType, and wrap the thunk result
in an optional, duplicating work done in the transform
- Witness thunk generation similarly had to handle the case
of upcasting to a base class to call the witness, and
casting the result of materializeForSet back to the right
type for properties defined on the base.
Now the materializeForSet cast sequence is a bit longer,
we unpack the returned tuple and do a convert_function
on the function, then pack it again -- before we would
unchecked_ref_cast the tuple, which is technically
incorrect since the tuple is not a ref, but IRGen didn't
seem to care...
To handle the conversions correctly, we add a third AST type
parameter to a transform, named inputType. Now, transforms
perform these conversions:
- OrigToSubst: L(origType, inputType) -> L(substType)
- SubstToOrig: L(inputType) -> L(origType, substType)
When we flip the direction of the transform while visiting
types in contravariant position, we also swap substType with
inputType.
Note that this is similar to how bridging thunks work, for
the same reason -- bridging thunks convert between AST types.
This is mostly just a nice cleanup that fixes some obscure
corner cases for now, but this functionality will be used
in a subsequent patch.
Swift SVN r31486
Also make it more accurate by lowering optional payload types, but
nothing depends on this right now.
Apologies for the recent stream of unrelated-looking NFCs -- the goal
here is to make a big upcoming patch easier to review.
Swift SVN r31480
- Generalize::transformFunction() had a couple of little optimizations
for emitting convert_function or thin_to_thick_function instead of
a thunk, if possible -- move this into code shared by all
transforms
- Nuke Generalize since it doesn't do anything special anymore
Swift SVN r31423
There are three implementations of this in SIL so far:
- in emitGeneralizedFunctionValue()
- in emitVTableMethod()
- in the SILVerifier
I haven't touched the latter yet, though.
Swift SVN r31422
the type-checker. The strategy for now is to just use this
for protocol witness thunk emission, where it is required
when generating a materializeForSet for storage that is
either implemented in a protocol extension or requires
reabstraction to the requirement's pattern.
Eventually, this should be generalized to the point that
we can use it for all materializeForSet emission, which
I don't think will take much. However, that's not really
the sort of instability we want to embrace for the current
release.
WIP towards rdar://21836671; currently disabled, so NFC.
Swift SVN r31072
Actually invoking such an override on an instance of the derived type
still doesn't work, unless you cast to the base type first. Fixing this
requires emitting a new vtable entry for the new signature and is
tracked in <rdar://problem/21435542>.
Fixes <rdar://problem/21364764>.
Swift SVN r29935
This patch attempts to fix rdar://problem/21452981, which Joe worked on
in r29572, but reverted because that patch had other changes that broke
stuff.
Swift SVN r29934
These still show up if you have a witness with a default argument, which the AST still represents as a single-element tuple, matched against a non-tuple orig type in the witness signature. Handle this by allowing getTupleElementType(0) on non-tuple AbstractionPatterns to work, and tweaking the parallel translation code to drill through single-element tuples and line up the contained scalars properly. Fixes rdar://problem/21452981. (Still left broken is the obnoxious single-element-tuple-of-tuple case, rdar://problem/21496105.)
Now with less Xcode autosave breakage.
Swift SVN r29572
These still show up if you have a witness with a default argument, which the AST still represents as a single-element tuple, matched against a non-tuple orig type in the witness signature. Handle this by allowing getTupleElementType(0) on non-tuple AbstractionPatterns to work, and tweaking the parallel translation code to drill through single-element tuples and line up the contained scalars properly. Fixes rdar://problem/21452981. (Still left broken is the obnoxious single-element-tuple-of-tuple case, rdar://problem/21496105.)
Swift SVN r29561
When a derived class specializes its base class, e.g. 'class Derived: Base<Int>', the natural abstraction levels of its methods may differ from the original base class's more abstract methods. Handle this by using the reabstraction machinery to thunk values when necessary. Merge the existing optionality thunking support into the reabstraction code, where witness thunking and similar convention adjustments may also be able to use it, if we desire. Fixes rdar://problem/19760292.
Swift SVN r28505
The translation code already handles translating in_guaranteed arguments
correctly. The assert was just too conservative.
<rdar://problem/20522878>
Swift SVN r27307
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
These aren't really orthogonal concerns--you'll never have a @thick @cc(objc_method), or an @objc_block @cc(witness_method)--and we have gross decision trees all over the codebase that try to hopscotch between the subset of combinations that make sense. Stop the madness by eliminating AbstractCC and folding its states into SILFunctionTypeRepresentation. This cleans up a ton of code across the compiler.
I couldn't quite eliminate AbstractCC's information from AST function types, since SIL type lowering transiently created AnyFunctionTypes with AbstractCCs set, even though these never occur at the source level. To accommodate type lowering, allow AnyFunctionType::ExtInfo to carry a SILFunctionTypeRepresentation, and arrange for the overlapping representations to share raw values.
In order to avoid disturbing test output, AST and SILFunctionTypes are still printed and parsed using the existing @thin/@thick/@objc_block and @cc() attributes, which is kind of gross, but lets me stage in the real source-breaking change separately.
Swift SVN r27095
The set of attributes that make sense at the AST level is increasingly divergent from those at the SIL level, so it doesn't really make sense for these to be the same. It'll also help prevent us from accidental unwanted propagation of attributes from the AST to SIL, which has caused bugs in the past. For staging purposes, start off with SILFunctionType's versions exactly the same as the FunctionType versions, which necessitates some ugly glue code but minimizes the potential disruption.
Swift SVN r27022
This is necessary for correctly dealing with non-standard
ownership conventions in secondary positions, and it should
also help with non-injective type imports (like BOOL/_Bool).
But right now we aren't doing much with it.
Swift SVN r26954
Previously some parts of the compiler referred to them as "fields",
and most referred to them as "elements". Use the more generic 'elements'
nomenclature because that's what we refer to other things in the compiler
(e.g. the elements of a bracestmt).
At the same time, make the API better by providing "getElement" consistently
and using it, instead of getElements()[i].
NFC.
Swift SVN r26894
We no longer need or use it since we can always refer to the same bit on
the applied function when deciding whether to inline during mandatory
inlining.
Resolves rdar://problem/19478366.
Swift SVN r26534
The deallocating parameter convention is a new convention put on a
non-trivial parameter if the caller function guarantees to the callee
that the parameter has the deallocating bit set in its object header.
This means that retains and releases do not need to be emitted on these
parameters even though they are non-trivial. This helps to solve a bug
in +0 self and makes it trivial for the optimizer to perform
optimizations based on this property.
It is not emitted yet by SILGen and will only be put on the self
argument of Deallocator functions.
Swift SVN r26179
If we have a C function pointer conversion, generate a thunk using the same logic we use for ObjC method thunks, and emit a pointer to that thunk as the C function pointer value. (This works for nongeneric, nonmember functions; generics will additionally need to apply generic parameters within the thunks. Static functions would need to gather the metatype as well.)
Swift SVN r25653
The materializeForSet accessor for a `dynamic` property needs to dynamically invoke the getter and setter of the property in order to allow for runtime modification, so it doesn't need to be dynamically dispatched itself. If the property came from an imported ObjC class, then we can't dynamically dispatch it without polluting the selector namespace. Introduce a new 'ForcedStaticDispatch' bit and set it in order to force `dynamic` materializeForSet accessors to be statically dispatched. (They can't be `final` because it's legal to override a dynamic property.) If the property came from ObjC, register materializeForSet as an external declaration so it gets generated by SIL. Fixes rdar://problem/18706056.
Swift SVN r24930
the call instead of during the formal evaluation of the argument.
This is the last major chunk of the semantic changes proposed
in the accessors document. It has two purposes, both related
to the fact that it shortens the duration of the formal access.
First, the change isolates later evaluations (as long as they
precede the call) from the formal access, preventing them from
spuriously seeing unspecified behavior. For example::
foo(&array[0], bar(array))
Here the value passed to bar is a proper copy of 'array',
and if bar() decides to stash it aside, any modifications
to 'array[0]' made by foo() will not spontaneously appear
in the copy. (In contrast, if something caused a copy of
'array' during foo()'s execution, that copy would violate
our formal access rules and would therefore be allowed to
have an arbitrary value at index 0.)
Second, when a mutating access uses a pinning addressor, the
change limits the amount of arbitrary code that falls between
the pin and unpin. For example::
array[0] += countNodes(subtree)
Previously, we would begin the access to array[0] before the
call to countNodes(). To eliminate the pin and unpin, the
optimizer would have needed to prove that countNodes didn't
access the same array. With this change, the call is evaluated
first, and the access instead begins immediately before the call
to +=. Since that operator is easily inlined, it becomes
straightforward to eliminate the pin/unpin.
A number of other changes got bundled up with this in ways that
are hard to tease apart. In particular:
- RValueSource is now ArgumentSource and can now store LValues.
- It is now illegal to use emitRValue to emit an l-value.
- Call argument emission is now smart enough to emit tuple
shuffles itself, applying abstraction patterns in reverse
through the shuffle. It also evaluates varargs elements
directly into the array.
- AllowPlusZero has been split in two. AllowImmediatePlusZero
is useful when you are going to immediately consume the value;
this is good enough to avoid copies/retains when reading a 'var'.
AllowGuaranteedPlusZero is useful when you need a stronger
guarantee, e.g. when arbitrary code might intervene between
evaluation and use; it's still good enough to avoid copies
from a 'let'. The upshot is that we're now a lot smarter
about generally avoiding retains on lets, but we've also
gotten properly paranoid about calling non-mutating methods
on vars.
(Note that you can't necessarily avoid a copy when passing
something in a var to an @in_guaranteed parameter! You
first have to prove that nothing can assign to the var during
the call. That should be easy as long as the var hasn't
escaped, but that does need to be proven first, so we can't
do it in SILGen.)
Swift SVN r24709
It was checking the current function's transparency rather than the
referenced function's transparency.
Fixing this did not seem to have a measureable impact on the performance
of -Onone code.
Fixes rdar://problem/19477711.
Swift SVN r24452
For now, conservatively retain them so they can be forwarded as +1 values, until we can push +0 rvalue support down into the forwarding and function application implementations. Preserve the old, technically incorrect behavior unless -enable-guaranteed-self is enabled to avoid punishing -Onone code until guaranteed self is enabled. (With guaranteed self and +0 rvalue support, the overhead this introduces should be avoidable in the code generator.)
Swift SVN r24374
as passing self by value, not by inout. This is the correct representation at
the AST level, and we now lower self references as the new @in_guaranteed
parameter convention. This allows SIL clients (like DI) to know that a nonmutating
protocol method does not mutate the pointee passed into the method.
This fixes:
<rdar://problem/19215313> let properties don't work with protocol method dispatch
<rdar://problem/15821762> Self argument of generic curried nonmutating instance methods is inout
Swift SVN r23864
isn't used yet, but will be for modeling the self argument passed to an
address-only witness implementation. NFC since all this code is dead :-)
Swift SVN r23857
Fixes a bug where dynamic dispatches of class methods or initializers through generic interfaces didn't redispatch to subclasses. Also fix up some logic errors noticed by inspection.
Swift SVN r22945
When we've already established that the optional has a value, using unchecked_take_enum_data_addr to directly extract the enum payload is sufficient and avoids a redundant call and check at -Onone. Keep using the _getOptionalValue stdlib function for checked optional wrapping operations such as "x!", so that the stdlib can remain in control of trap handling policy.
The test/SIL/Serialization failures on the bot seem to be happening sporadically independent of this patch, and I can't reproduce failures in any configuration I've tried.
Swift SVN r22537
When we've already established that the optional has a value, using unchecked_take_enum_data_addr to directly extract the enum payload is sufficient and avoids a redundant call and check at -Onone. Keep using the _getOptionalValue stdlib function for checked optional wrapping operations such as "x!", so that the stdlib can remain in control of trap handling policy.
Swift SVN r22533
Now the SILLinkage for functions and global variables is according to the swift visibility (private, internal or public).
In addition, the fact whether a function or global variable is considered as fragile, is kept in a separate flag at SIL level.
Previously the linkage was used for this (e.g. no inlining of less visible functions to more visible functions). But it had no effect,
because everything was public anyway.
For now this isFragile-flag is set for public transparent functions and for everything if a module is compiled with -sil-serialize-all,
i.e. for the stdlib.
For details see <rdar://problem/18201785> Set SILLinkage correctly and better handling of fragile functions.
The benefits of this change are:
*) Enable to eliminate unused private and internal functions
*) It should be possible now to use private in the stdlib
*) The symbol linkage is as one would expect (previously almost all symbols were public).
More details:
Specializations from fragile functions (e.g. from the stdlib) now get linkonce_odr,default
linkage instead of linkonce_odr,hidden, i.e. they have public visibility.
The reason is: if such a function is called from another fragile function (in the same module),
then it has to be visible from a third module, in case the fragile caller is inlined but not
the specialized function.
I had to update lots of test files, because many CHECK-LABEL lines include the linkage, which has changed.
The -sil-serialize-all option is now handled at SILGen and not at the Serializer.
This means that test files in sil format which are compiled with -sil-serialize-all
must have the [fragile] attribute set for all functions and globals.
The -disable-access-control option doesn't help anymore if the accessed module is not compiled
with -sil-serialize-all, because the linker will complain about unresolved symbols.
A final note: I tried to consider all the implications of this change, but it's not a low-risk change.
If you have any comments, please let me know.
Swift SVN r22215
