This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
Now that in OSSA `partial_apply [on_stack]`s are represented as owned
values rather than stack locations, it is possible for their destroys to
violate stack discipline. A direct lowering of the instructions to
non-OSSA would violate stack nesting.
Previously, when inlining, it was assumed that non-coroutine callees
maintained stack discipline. And, when inlining an OSSA function into a
non-OSSA function, OSSA instructions were lowered directly. The result
was that stack discipline could be violated.
Here, when inlining a function in OSSA form into a function lowered out
of OSSA form, stack nesting is fixed up.
Previously, there was an -Xllvm option to verify after all inlining to a
particlar caller. That makes it a chore to track down which apply's
inlining resulted in invalid code. Here, a new option is added that
verifies after each run of the inliner.
- SILPackType carries whether the elements are stored directly
in the pack, which we're not currently using in the lowering,
but it's probably something we'll want in the final ABI.
Having this also makes it clear that we're doing the right
thing with substitution and element lowering. I also toyed
with making this a scalar type, which made it necessary in
various places, although eventually I pulled back to the
design where we always use packs as addresses.
- Pack boundaries are a core ABI concept, so the lowering has
to wrap parameter pack expansions up as packs. There are huge
unimplemented holes here where the abstraction pattern will
need to tell us how many elements to gather into the pack,
but a naive approach is good enough to get things off the
ground.
- Pack conventions are related to the existing parameter and
result conventions, but they're different on enough grounds
that they deserve to be separated.
`getValue` -> `value`
`getValueOr` -> `value_or`
`hasValue` -> `has_value`
`map` -> `transform`
The old API will be deprecated in the rebranch.
To avoid merge conflicts, use the new API already in the main branch.
rdar://102362022
This invalidation kind is used when a compute-effects pass changes function effects.
Also, let optimization passes which don't change effects only invalidate the `FunctionBody` and not `Everything`.
The main point of this change is to make sure that a shared function always has a body: both, in the optimizer pipeline and in the swiftmodule file.
This is important because the compiler always needs to emit code for a shared function. Shared functions cannot be referenced from outside the module.
In several corner cases we missed to maintain this invariant which resulted in unresolved-symbol linker errors.
As side-effect of this change we can drop the shared_external SIL linkage and the IsSerializable flag, which simplifies the serialization and linkage concept.
There are three major changes here:
1. The addition of "SILFunctionTypeRepresentation::CXXMethod".
2. C++ methods are imported with their members *last*. Then the arguments are switched when emitting the IR for an application of the function.
3. Clang decls are now marked as foreign witnesses.
These are all steps towards being able to have C++ protocol conformance.
Fix innumerable latent bugs with iterator invalidation and callback invocation.
Removes dead code earlier and chips away at all the redundant copies the compiler generates.
It's not needed anymore with delayed instruction deletion.
It was used for two purposes:
1. For analysis, which cache instructions, to avoid dangling instruction pointers
2. For passes, which maintain worklists of instructions, to remove a deleted instructions from the worklist. This is now done by checking SILInstruction::isDeleted().
Instead, put the archetype->instrution map into SIlModule.
SILOpenedArchetypesTracker tried to maintain and reconstruct the mapping locally, e.g. during a use of SILBuilder.
Having a "global" map in SILModule makes the whole logic _much_ simpler.
I'm wondering why we didn't do this in the first place.
This requires that opened archetypes must be unique in a module - which makes sense. This was the case anyway, except for keypath accessors (which I fixed in the previous commit) and in some sil test files.
If we know that we have a FunctionRefInst (and not another variant of FunctionRefBaseInst), we know that getting the referenced function will not be null (in contrast to FunctionRefBaseInst::getReferencedFunctionOrNull).
NFC
In recordDeadFunction, we look at operands of an instruction to be deleted,
and add back the defining instruction of the operands to the worklist.
This works in general when we are deleting dead instructions
recursively.
But we also consider, an instruction with only debug uses as dead. So
when we are deleting a debug instruction, we may have already deleted
its operand's defining instruction. So it would be incorrect to add it
to the worklist.
... and use that API in FullApplySite::insertAfterInvocation.
Also change FullApplySite::insertAfterInvocation/insertAfterFullEvaluation to directly pass a SILBuilder instead of just an insertion point to the callback.
This makes more sense (given the function names) and simplifies the usages.
It's a NFC.
Because partial_apply consumes it's arguments we need to copy them. This was done for "direct" parameters but not for address parameters.
rdar://problem/64035105
HOW THIS WAS DONE: I did this by refactoring the last usages of checkValue into
a higher level API that uses checkValue as an implementation detail:
completeConsumingUseSet(...). All of these places in
MandatoryInlining/PredictableMemOpts all wanted behavior where we complete a set
of consuming uses for a value, detecting if the consuming use is in a different
loop nest from the value.
WHY DO THIS: The reason why I wanted to do this is that checkValue is a lower
level API that drives the actual low level computation. We shouldn't expose its
interface to the LinearLifetimeChecker's users since it is our own private
implementation detail that also has some sharp edges.
AN ADDITIONAL BENEFIT: Additionally by hiding the declaration of checkValue, the
last public use of LinearLifetimeError and ErrorBehaviorKind was not
private. This allowed me to then move the declarations of those two to a private
header (./lib/SIL/LinearLifetimeCheckerPrivate.h) and make their declarations
private to LinearLifetimeChecker as well. As such, I renamed them to
LinearLifetimeChecker::Error and LinearLifetimeChecker::ErrorBehaviorKind.
Devirtualizing try_apply modified the CFG, but passes that run
devirtualization were not invalidating any CFG analyses, such as the
domtree.
This could hypothetically have caused miscompilation, but will be
caught by running with -sil-verify-all.
This is just better information to have since one wants to not only know the
instruction, but also the specific value used on the instruction since behavior
can vary depending upon that. The operand is what ties the two together so it is
a natural fit.
Now that this is done, I am going to work on refactoring out converting a
LiveRange from @owned -> @guaranteed. It will be a consuming operation using a
move operator since once the transformation has completed, the LiveRange no
longer exists.
I need this refactored functionality since I am going to need it when
eliminating phi-webs.
The only reason why BranchPropagatedUser existed was because early on in SIL, we
weren't sure if cond_br should be able to handle non-trivial values in
ossa. Now, we have reached the point where we have enough experience to make the
judgement that it is not worth having in the representation due to it not
holding its weight.
Now that in ToT we have banned cond_br from having non-trivial operands in ossa,
I can just eliminate BranchPropagatedUser and replace it with the operands that
we used to construct them!
A few notes:
1. Part of my motiviation in doing this is that I want to change LiveRange to
store operands instead of instructions. This is because we are interested in
being able to understand the LiveRange at a use granularity in cases where we
have multiple operands. While doing this, I discovered that I needed
SILInstructions to use the Linear Lifetime Checker. Then I realized that now was
the time to just unwind BranchPropagatedUser.
2. In certain places in SemanticARCOpts, I had to do add some extra copies to
transform arrays of instructions from LiveRange into their operand form. I am
going to remove them in a subsequent commit when I change LiveRange to work on
operands. I am doing this split to be incremental.
3. I changed isSingleInitAllocStack to have an out array of Operand *. The only
user of this code is today in SemanticARCOpts and this information is fed to the
Linear Lifetime Checker, so I needed to do it.
OwnershipUtils.h is growing a bit and I want to use it to store abstract higher
level utilities for working with ossa. LinearLifetimeChecker is just a low level
detail of that, so it makes sense to move it out now.
Changes:
* Allow optimizing partial_apply capturing opened existential: we didn't do this originally because it was complicated to insert the required alloc/dealloc_stack instructions at the right places. Now we have the StackNesting utility, which makes this easier.
* Support indirect-in parameters. Not super important, but why not? It's also easy to do with the StackNesting utility.
* Share code between dead closure elimination and the apply(partial_apply) optimization. It's a bit of refactoring and allowed to eliminate some code which is not used anymore.
* Fix an ownership problem: We inserted copies of partial_apply arguments _after_ the partial_apply (which consumes the arguments).
* When replacing an apply(partial_apply) -> apply and the partial_apply becomes dead, avoid inserting copies of the arguments twice.
These changes don't have any immediate effect on our current benchmarks, but will allow eliminating curry thunks for existentials.
Specifically:
1. I renamed the method insertAfter -> insertAfterInvocation and added an
ehaustive switch to ensure that we properly update this code if we add new apply
sites.
2. I added a new method insertAfterFullEvaluation that is like
insertAfterInvocation except that the callback is called with insertion points
after the end/abort apply instead of after the initial invocation of the
begin_apply.
Specifically, we may have a loaded callee value from a stack value. This change
just makes it so that we do not optimize if we do not actually have the box.
rdar://56386236
The XXOptUtils.h convention is already established and parallels
the SIL/XXUtils convention.
New:
- InstOptUtils.h
- CFGOptUtils.h
- BasicBlockOptUtils.h
- ValueLifetime.h
Removed:
- Local.h
- Two conflicting CFG.h files
This reorganization is helpful before I introduce more
utilities for block cloning similar to SinkAddressProjections.
Move the control flow utilies out of Local.h, which was an
unreadable, unprincipled mess. Rename it to InstOptUtils.h, and
confine it to small APIs for working with individual instructions.
These are the optimizer's additions to /SIL/InstUtils.h.
Rename CFG.h to CFGOptUtils.h and remove the one in /Analysis. Now
there is only SIL/CFG.h, resolving the naming conflict within the
swift project (this has always been a problem for source tools). Limit
this header to low-level APIs for working with branches and CFG edges.
Add BasicBlockOptUtils.h for block level transforms (it makes me sad
that I can't use BBOptUtils.h, but SIL already has
BasicBlockUtils.h). These are larger APIs for cloning or removing
whole blocks.
Often times when one is working with apply sites, one wants to insert
instructions after both terminator apply sites and normal apply sites. This can
get ackward and result in unnecessary if-else code that is all really doing the
same thing, once for terminator instructions and once for normal instructions.
insertAfterApply is a helper method that MandatoryInlining uses for this purpose
and it is so useful that I want to use it somewhere else in closure lifetime
fixup as well. I am moving it onto apply site since that is the true abstraction
that insertAfterApply works with.
This commit only changes how BranchPropagatedUser is constructed and does not
change the internal representation. This is a result of my noticing that
BranchPropagatedUser could also use an operand internally to represent its
state. To simplify how I am making the change, I am splitting the change into
two PRs that should be easy to validate:
1. A commit that maps how the various users of BranchPropagatedUser have been
constructing BPUs to a single routine that takes an Operand. This leaves
BranchPropagatedUser's internal state alone as well as its user the Linear
Lifetime Checker.
2. A second commit that changes the internal bits of the BranchPropagatedUser to
store an Operand instead of a PointerUnion.
This will allow me to use the first commit to validate the second.
This is just a simple refactoring commit in preparation for hiding more of the
details of the linear lifetime checker. This is NFC, just moving around code.
This bug is caused by a quirk in the API of the linear lifetime
checker. Specifically, even though valueHasLinearLifetime is passed a SILValue
(the value whose lifetime one is checking), really it doesnt care about that
value (except for error diagnostics). Really it just cares about the parent
block of the value since it assumes that the value is guaranteed to dominate all
uses.
This creates a footgun when if one is writing code using "generic ossa/non-ossa"
routines on SILBuilder (the emit*Operation methods), if one in non-ossa code
calls that function, it returns the input value of the strong_retain. This
causes the linear lifetime error, to use the parent block of the argument of the
retain, instead of the parent block of the retain itself. This then causes it to
find the wrong leaking blocks and thus insert destroys in the wrong places.
I fix this problem in this commit by noting that the partial apply is our
original insertion point for the copy, so of course it is going to be in the
same block. So I changed the linear lifetime checker to check for leaks with
respect to the partial applies result.
In a subsequent commit, I am going to add a new API on top of this that is based
around the use of the value by the partial apply (maybe
extendLifetimeFromUseToInsertionPoint?). By using the use, it will express in
code more clearly what is happening here and will insert the copy for you.
rdar://54234011
This at least ensures that we error immediately after processing the bad
root function. NOTE: we will inline recursively into it still, but at least we
stop before processing the entire module.
This was exposed by test/SILOptimizer/diagnostic_constant_propagation.swift. It
isn't a pattern in the mandatory inlining tests. I added some tests for it.
