Instead of interleaving typechecking and parsing
for SIL files, first parse the file for Swift
decls by skipping over any intermixed SIL decls.
Then we can perform type checking, and finally SIL
parsing where we now skip over Swift decls.
This is an intermediate step to requestifying the
parsing of a source file for its Swift decls.
SIL differentiability witnesses are a new top-level SIL construct mapping
"original" SIL functions to derivative SIL functions.
SIL differentiability witnesses have the following components:
- "Original" `SILFunction`.
- SIL linkage.
- Differentiability parameter indices (`IndexSubset`).
- Differentiability result indices (`IndexSubset`).
- Derivative `GenericSignature` representing differentiability generic
requirements (optional).
- JVP derivative `SILFunction` (optional).
- VJP derivative `SILFunction` (optional).
- "Is serialized?" bit.
This patch adds the `SILDifferentiabilityWitness` data structure, with
documentation, parsing, and printing.
Resolves TF-911.
Todos:
- TF-1136: upstream `SILDifferentiabilityWitness` serialization.
- TF-1137: upstream `SILDifferentiabilityWitness` verification.
- TF-1138: upstream `SILDifferentiabilityWitness` SILGen from
`@differentiable` and `@derivative` attributes.
- TF-20: robust mangling for `SILDifferentiabilityWitness` names.
The specific problem here is this:
```
sil @builtin_array_opt_index_raw_pointer_to_index_addr_no_crash : $@convention(thin) (Builtin.RawPointer, Builtin.
Word) -> Builtin.Word {
bb0(%0 : $Builtin.RawPointer, %1 : $Builtin.Word):
%2 = index_raw_pointer %0 : $Builtin.RawPointer, %1 : $Builtin.Word
%3 = pointer_to_address %2 : $Builtin.RawPointer to [strict] $*Builtin.Word
%4 = load %3 : $*Builtin.Word
return %4 : $Builtin.Word
}
```
before this commit, we unconditionally called getDefiningInstruction when
looking at %1. This of course returned a null value causing the compiler to
crash in a dyn_cast<TupleExtractInst>().
rdar://59138369
For those who are unaware, a transformation terminator is a terminator like
switch_enum/checked_cast_br that always dominate their successor blocks. Since
they dominate their successor blocks by design and transform their input into
the args form, we can validate that they obey guaranteed ownership semantics
just like a forwarding instruction.
Beyond removing unnecessary code bloat, this also makes it significantly more
easier to optimize/work with transformation terminators when converting @owned
-> @guaranteed since we do not need to find end_borrow points when the owned
value is consumed.
<rdar://problem/59097063>
The original design was to make it so that end_borrow tied at the use level its
original/borrowed value. So we would have:
```
%borrowedVal = begin_borrow %original
...
end_borrow %borrowedVal from %original
```
In the end we decided not to use that design and instead just use:
```
%borrowedVal = begin_borrow %original
...
end_borrow %borrowedVal
```
In order to enable that transition, I left the old API for end_borrow that took
both original and borrowedVal and reimplemented it on top of the new API that
just took the borrowedVal (i.e. the original was just a dead arg).
Now given where we are in the development, it makes sense to get rid of that
transition API and move to just use the new API.
A branch propagated user that isn't a cond_br is layout compatible with a
SILInstruction *. This helper function converts from ArrayRef<SILInstruction *>
-> ArrayRef<BranchPropagatedUser> but also in asserts builds checks that our
invariant (namely all of the 'SILInstruction *' are not cond_br.
The current way that VarDecl::isLazilyInitializedGlobal() is implemented does
not work in the debugger, since the DeclContext of all VarDecls are deserialized
Swift modules. By adding a bit to the VarDecl we can recover the fact that a
VarDecl was in fact a global even in the debugger.
<rdar://problem/58939370>
Diagnose an attempt to reference a top-level name shadowed by
a local member e.g.
```swift
extension Sequence {
func test() -> Int {
return max(1, 2)
}
}
```
Here `min` refers to a global function `min<T>(_: T, _: T)` in `Swift`
module and can only be accessed by adding `Swift.` to it, because `Sequence`
has a member named `min` which accepts a single argument.
