Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
Compute, update and handle borrowed-from instruction in various utilities and passes.
Also, used borrowed-from to simplify `gatherBorrowIntroducers` and `gatherEnclosingValues`.
Replace those utilities by `Value.getBorrowIntroducers` and `Value.getEnclosingValues`, which return a lazily computed Sequence of borrowed/enclosing values.
"reborrow" flag on the SILArgument avoids transitive walk over the phi operandsi
to determine if it is a reborrow in multiple utilities.
SIL transforms must keep the flag up-to-date by calling SILArgument::setReborrow.
SILVerifier checks to ensure the flag is not invalidated.
Currently "escaping" is not used anywhere.
With f9861ec9c0 we consider SILPhiArgument in a
block with no predecessors as phis, remove assert that we expect non-empt predecessors
to reflect this change.
Add TermInst::forwardedOperand.
Add SILArgument::forwardedTerminatorResultOperand. This API will be
moved into a proper TerminatorResult abstraction.
Remove getSingleTerminatorOperand, which could be misused because it's
not necessarilly forwarding ownership.
Remove the isTransformationTerminator API, which is not useful or well
defined.
Rewrite several instances of complex logic to handle block arguments
with the simple terminator result API. This defines away potential
bugs where we don't detect casts that perform implicit conversion.
Replace uses of the SILPhiArgument type and code that explicitly
handle block arguments. Control flow is irrelevant in these
situations. SILPhiArgument needs to be deleted ASAP. Instead, use
simple APIs like SILArgument::isTerminatorResult(). Eventually this
will be replaced by a TerminatorResult type.
With the change to include `SmallVector.h` directly in `LLVM.h` rather
than forward declaring in the only case it matters (ie. Clang <= 5),
these fixes are no longer needed. Since defaulted version is preferred
when there's no better choice (which is presumably the case if that's
how they were originally added), use it instead. Some uses were instead
changed to add `llvm::` so remove that too.
The use of the SWIFT_INLINE_BITFIELD macros in SILNode were a constant source of confusion and bugs.
With this refactoring I tried to simplify the definition of "shared fields" in SILNode, SILValue and SILInstruction classes:
* Move `kind`, `locationKindAndFlags` and the 32-bit fields out of the 64-bitfield into their own member variables. This avoids _a lot_ of manual bit position computations.
* Now we have two separate "shared fields": an 8-bit field (e.g. for boolean flags) and a 32-bit field (e.g. for indices, which can potentially get large). Both fields can be used independently. Also, they are not "bit fields" per se. Instructions can use the field e.g. as a `bool`, `uint32_t`, or - if multiple flags are to be stored - as a packed bit field.
* With these two separate fields, we don't have the need for defining bitfields both in a base class _and_ in a derived value/instruction class. We can get rid of the complex logic which handles such cases. Just keep a check to catch accidental overlaps of fields in base and derived classes.
* Still use preprocessor macros for the implementation, but much simpler ones than before.
* Add documentation.
This subclass of SILArgument should be eliminated--it's not always a
phi, and whether it is a "phi argument" has nothing whatsoever to do
with the opcode. That is a property of a value's uses, not a property of the
value.
Until then, provide a logical and useful API within the type. This
often avoids the need to explicitly cast to a SILPhiArgument type and
avoids a lot of boilerplate in code that deals with phis.
Note: PhiOperand and PhiValue are improved abstractions on top of this
API. But the SILArgument-level API is still an important bridge
between SILArgument and other phi abstractions.
In OSSA, we do not allow for address phis, but in certain cases the logic of
LoopRotate really wants them. To work around this issue, I added some code in
this PR to loop rotate that as a post-pass fixes up any address phis by
inserting address <-> raw pointer adapters and changing the address phi to
instead be of raw pointer type.
This removes the ambiguity when casting from a SingleValueInstruction to SILNode, which makes the code simpler. E.g. the "isRepresentativeSILNode" logic is not needed anymore.
Also, it reduces the size of the most used instruction class - SingleValueInstruction - by one pointer.
Conceptually, SILInstruction is still a SILNode. But implementation-wise SILNode is not a base class of SILInstruction anymore.
Only the two sub-classes of SILInstruction - SingleValueInstruction and NonSingleValueInstruction - inherit from SILNode. SingleValueInstruction's SILNode is embedded into a ValueBase and its relative offset in the class is the same as in NonSingleValueInstruction (see SILNodeOffsetChecker).
This makes it possible to cast from a SILInstruction to a SILNode without knowing which SILInstruction sub-class it is.
Casting to SILNode cannot be done implicitly, but only with an LLVM `cast` or with SILInstruction::asSILNode(). But this is a rare case anyway.
This removes the ambiguity when casting from a SingleValueInstruction to SILNode, which makes the code simpler. E.g. the "isRepresentativeSILNode" logic is not needed anymore.
Also, it reduces the size of the most used instruction class - SingleValueInstruction - by one pointer.
Conceptually, SILInstruction is still a SILNode. But implementation-wise SILNode is not a base class of SILInstruction anymore.
Only the two sub-classes of SILInstruction - SingleValueInstruction and NonSingleValueInstruction - inherit from SILNode. SingleValueInstruction's SILNode is embedded into a ValueBase and its relative offset in the class is the same as in NonSingleValueInstruction (see SILNodeOffsetChecker).
This makes it possible to cast from a SILInstruction to a SILNode without knowing which SILInstruction sub-class it is.
Casting to SILNode cannot be done implicitly, but only with an LLVM `cast` or with SILInstruction::asSILNode(). But this is a rare case anyway.
`get_async_continuation[_addr]` begins a suspend operation by accessing the continuation value that can resume
the task, which can then be used in a callback or event handler before executing `await_async_continuation` to
suspend the task.
This is letting me refactor the implementation of every place that I work with
branches as "ownership phi operands" to instead work with
OwnershipPhiOperand. In a future commit, I am going to use this to add support
for optimizing structs and tuples that have multiple owned incoming values.
<rdar://problem/63950481>
Specifically, I split it into 3 initial categories: IR, Utils, Verifier. I just
did this quickly, we can always split it more later if we want.
I followed the model that we use in SILOptimizer: ./lib/SIL/CMakeLists.txt vends
a macro (sil_register_sources) to the sub-folders that register the sources of
the subdirectory with a global state variable that ./lib/SIL/CMakeLists.txt
defines. Then after including those subdirs, the parent cmake declares the SIL
library. So the output is the same, but we have the flexibility of having
subdirectories to categorize source files.
