Enhance the utility with the ability to end lifetimes of lexical values
at indicated instructions, overriding the usual behavior of maintaining
such lifetimes' previous endpoints (modulo non-deinit-barrier
instructions).
Parameterized `extendUnconsumedLiveness` on the ends of interest and the
action to take when visiting the extended boundary and named the
resulting function `visitExtendedUnconsumedBoundary`.
The reason why we are doing this is that otherwise, we have that the alloc_stack
formed for the result is disconnected and despite the fact that we merge it into
the actor region of the class method, we do not have that the alloc_stack
specifically is marked when we attempt to squelch Please.
This patch fixes that problem by detecting when an alloc_stack is being used as
a temporary for an out parameter and makes the alloc_stack initially isolated as
appropriate. It only does this in the specific cases where we can pattern match
it which in my limited testing has handled everything.
When merging SILIsolationInfo for regions, we want to drop
nonisolated(unsafe). This is important since nonisolated(unsafe) should only
apply to the specific "value" that it belongs to, not the entire region.
This creates a problem since in a few places in the code base we initialize a
value (producing a disconnected value) and then initialize it by merging in an
actor isolation. This no longer work since we will then always have
nonisolated(unsafe) stripped, so no values would ever be considered to be
nonisolated(unsafe). After analyzing the use case, I realized that these were
just initialization patterns and in this commit, I added a specific
initialization operation called SILIsolationInfo::initializeTrackableValue and
eliminated those calls to SILIsolationInfo::mergeIsolationRegionInfo.
Since SILIsolationInfo no longer has any merge operation on it, I then
eliminated that code in this commit. This completes the behavior split that I
put into the type system in the last commit. Specifically, I defined a
composition type called SILDynamicMergedIsolationInfo. It represents a
SILIsolationInfo that has been merged... that is why I called it the
DynamicMergedIsolationInfo. It could probably use a better name = (.
This fixes one of the last weird test case that I wrote where we were not letting through valid
nonisolated(unsafe) code.
At the same time, I discovered an additional issue (which can be seen in the
TODOs in this commit), where we are being too conservative around a non-Sendable
class var field. I am going to fix that in the next commit.
rdar://128299305
DISCUSSION: The analysis itself is unable to emit errors. So we achieve the same
functionality by in such cases emitting a partition op that signals to our user
that when they process that partition op they should emit an "unknown pattern"
error at the partition op's instructions.
I have wanted this for a long time, but I never got around to it.
Specifically, I introduced a new composition type called
SILDynamicMergedIsolationInfo that just contains a
SILIsolationInfo. Importantly, whenever one merges a SILIsolationInfo with
another SILIsolationInfo, one gets back a SILDynamicMergedIsolationInfo.
The reason why I am doing this is that we drop nonisolated(unsafe) when merging
so I want to ensure that parts of the code that use merging (where the dropping
occurs) and normal SILIsolationInfo where we do not want to merge is
distinguished.
I made sure we match what we get without region isolation by turning off region
isolation in one of the test runs on the test for this.
There is one problem where for non-final classes with nonisolated(unsafe) var
fields, we currently do not properly squelch since I need to do more
infrastructure work. I am going to do that in the next commit.
rdar://128299305
The design change here is that instead of just initializing the regionInfo with
disconnected, we set it as .none and if we see .none, just return a newly
construct disconnected isolation region info when getIsolationRegionInfo() is
called.
This enables us to provide a setIsolationRegionInfo() helper for
RegionAnalysisValueMap::getTrackableValue that does not perform a merge. This is
important since for nonisolated(unsafe), we want to not have nonisolated(unsafe)
propagate through merging. So if we use merging to initialize the internal
regionInfo state of a SILIsolationInfo, we will never have a SILIsolationInfo
with that bit set since it will be lost in the merge. So we need some sort of
other assignment operator. Noting that we should only compute a value's
SILIsolationInfo once in RegionAnalysisValueMap before we cache it in the map,
it made sense to just represent it as an optional that way we can guarantee that
the regionInfo is only ever set exactly once by that routine.
[serialized_for_package] if Package CMO is enabled. The latter kind
allows a function to be serialized even if it contains loadable types,
if Package CMO is enabled. Renamed IsSerialized_t as SerializedKind_t.
The tri-state serialization kind requires validating inlinability
depending on the serialization kinds of callee vs caller; e.g. if the
callee is [serialized_for_package], the caller must be _not_ [serialized].
Renamed `hasValidLinkageForFragileInline` as `canBeInlinedIntoCaller`
that takes in its caller's SerializedKind as an argument. Another argument
`assumeFragileCaller` is also added to ensure that the calle sites of
this function know the caller is serialized unless it's called for SIL
inlining optimization passes.
The [serialized_for_package] attribute is allowed for SIL function, global var,
v-table, and witness-table.
Resolves rdar://128406520
This ensures that we can properly compute isolation for generic types that
conform to AnyActor.
I found this by playing with test cases from the previous commit. We would not
find an actor type for the actor instance isolation and would fall back along an
incorrect path.
rdar://128021548
As part of this I went through how we handled inference and rather than using a
grab-bag getActorIsolation that was confusing to use, I created split APIs for
specific use cases (actor instance, global actor, just an apply expr crossing)
that makes it clearer inside the SILIsolationInfo::get* APIs what we are
actually trying to model. I found a few issues as a result and fixed most of
them if they were small. I also fixed one bigger one around computed property
initializers in the next commit. There is a larger change I didn't fix around allowing function
ref/partial_apply with isolated self parameters have a delayed flow sensitive
actor isolation... this will be fixed in a subsequent commit.
This also fixes a bunch of cases where we were printing actor-isolated instead
of 'self' isolated.
rdar://127295657
Specifically, the partition unit tests pass in bogus instructions/operands so we
cannot call /any/ methods on them. So I created stubed out helpers on the
evaluator that in the case of mocking just return a default initialized
SILIsolationInfo().
I have been using these in TransferNonSendable and they are useful in terms of
reducing the amount of code that one has to type to use this API. I am going to
need to use it in SILIsolationInfo, so it makes sense to move it into
SILOptimizer/Utils.
NFCI.
The reason why I am doing this is that really we are running two different
dataflow equations at the same time... one for propagating tracking transferring
sets and the other for propagating regions. Since at the source level the two
dataflow problems are very interrelated, I was unable to come up with an example
where we fail to iterate because of this, but I would like to be sure that we do
not hit one, so I am fixing this here.
rdar://126170014
This is backing out an approach that I thought would be superior, but ended up
causing problems.
Originally, we mapped a region number to an immutable pointer set containing
Operand * where the region was tranferred. This worked great for a time... until
I began to need to propagate other information from the transferring code in the
analysis to the actual diagnostic emitter.
To be able to do that, my thought was to make a wrapper type around Operand
called TransferringOperand that contained the operand and the other information
I needed. This seemed to provide me what I wanted but I later found that since
the immutable pointer set was tracking TransferringOperands which were always
newly wrapped with an Operand *, we actually always created new pointer
sets. This is of course wasteful from a memory perspective, but also prevents me
from tracking transferring operand sets during the dataflow since we would never
converge.
In this commit, I fix that issue by again tracking just an Operand * in the
TransferringOperandSet and instead map each operand to a state structure which
we merge dataflow state into whenever we visit it. This provides us with
everything we need to in the next commit to including a region -> transferring
operand set equality check in our dataflow equations and always converge.
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.
This ensures that we can efficiently iterate over the map which we will need to
do for equality queries.
I am going to add the equality queries in a subsequent commit. Just chopping off
a larger commit.
Specifically:
1. I copy the history that we have been tracking from the transferring operand
value at the transfer point. This is then available for use to emit diagnostics.
2. I added the ability for SILIsolationInfo to not only track the ActorIsolation
of an actor isolated value, but also if we have a value, we can track that as
well. Since we now track a value for task isolated and actor isolated
SILIsolationInfo, I just renamed the field to isolatedValue and moved it out of
the enum.
In a subsequent commit, I am going to wire it up to a few diagnostics.
rdar://123479934
We package all isolation history nodes from a single instruction by placing a
sequence boundary at the bottom. When ever we pop, we actually pop a PartitionOp
at a time meaning that we pop until we see a SequenceBoundary. Thus the sequence
boundary will always be the last element visited when popping meaning that it is
a convenient place to stick the SILLocation associated with the entire
PartitionOp. As a benefit, there was some unused space in IsolationHistory::Node
for that case since we were not using the std::variant field at all.
This means that I added an IsolationHistory field to Partition. Just upstreaming
the beginning part of this work. I added some unittests to exercise the code as
well. NOTE: This means that I did need to begin tracking an
IsolationHistoryFactory and propagating IsolationHistory in the pass
itself... but we do not use it for anything.
A quick overview of the design.
IsolationHistory is the head of an immutable directed acyclic graph. It is
actually represented as an immutable linked list with a special node that ties
in extra children nodes. The users of the information are expected to get a
SmallVectorImpl and process those sibling nodes afterwards. The reason why we
use an immutable approach is that it fits well with the problem and saves space
since different partitions could be pointing at the same linked list
node. Operations occur on an isolation history by pushing/popping nodes. It is
assumed that the user will push nodes in batches with a sequence boundary at the
bottom of the addition which signals to stop processing nodes.
Tieing this together, each Partition within it contains an IsolationHistory. As
the PartitionOpEvaluator applies PartitionOps to Partition in
PartitionOpEvaluator::apply, the evaluator also updates the isolation history in
the partition by first pushing a SequenceBoundary node and then pushing nodes
that will undo the operation that it is performing. This information is used by
the method Partition::popHistory. This pops linked list nodes from its history,
performing the operation in reverse until it hits a SequenceBoundary node.
This allows for one to rewind Partition history. And if one stashes an isolation
history as a target, one can even unwind a partition to what its state was at a
specific transfer point or earlier. Once we are at that point, we can begin
going one node back at a time and see when two values that we are searching for
no longer are apart of the same region. That is a place where we want to emit a
diagnostic. We then process until we find for both of our values history points
where they were the immediate reason why the two regions merge.
rdar://123479934
This should be NFC since the only case where I used this was with self... and I
found another way of doing that using the API I added in the previous commit.
I fixed a bunch of small issues around here that resulted in a bunch of radars
being fixed. Specifically:
1. I made it so that we treat function_refs that are from an actor isolated
function as actor isolated instead of sendable.
2. I made it so that autoclosures which return global actor isolated functions
are treated as producing a global actor isolated function.
3. I made it so that we properly handle SILGen code patterns produced by
Sendable GlobalActor isolated things.
rdar://125452372
rdar://121954871
rdar://121955895
rdar://122692698
ActorIsolation already has a "I have no value case": unspecified. Lets just use
that.
Just a mistake I made that I am trying to fix before anything further depends on
this code.
To squelch errors, we need access to functionality not available in the
unittests. The unittests do not require this functionality anyways, so just
disable squelching during the unittests.
To be more specific this means that either:
1. The use is actually isolated to the same actor. This could mean that the
use is global actor isolated to the same function.
2. The use is nonisolated but is executing within a function that is globally
isolated to the same isolation domain.
rdar://123474616
This issue can come up when a value is initially statically disconnected, but
after we performed dataflow, we discovered that it was actually actor isolated
at the transfer point, implying that we are not actually transferring.
Example:
```swift
@MainActor func testGlobalAndGlobalIsolatedPartialApplyMatch2() {
var ns = (NonSendableKlass(), NonSendableKlass())
// Regions: (ns.0, ns.1), {(mainActorIsolatedGlobal), @MainActor}
ns.0 = mainActorIsolatedGlobal
// Regions: {(ns.0, ns.1, mainActorIsolatedGlobal), @MainActor}
// This is not a transfer since ns is already main actor isolated.
let _ = { @MainActor in
print(ns)
}
useValue(ns)
}
```
To do this, I also added to SILFunction an actor isolation that SILGen puts on
the SILFunction during pre function visitation. We don't print it or serialize
it for now.
rdar://123474616
Just making PartitionUtils.h a little easier to walk through by moving more of
the impl into the .cpp file. This reduces the header from ~1500 lines to ~950
lines which is more managable. This is especially important since I am going
to be adding IsolationHistory to the header file which will expand it even
further.
As an example of the change:
- // expected-note @-1 {{'x' is transferred from nonisolated caller to main actor-isolated callee. Later uses in caller could race with potential uses in callee}}
+ // expected-note @-1 {{transferring disconnected 'x' to main actor-isolated callee could cause races in between callee main actor-isolated and local nonisolated uses}}
Part of the reason I am doing this is that I am going to be ensuring that we
handle a bunch more cases and I wanted to fix this diagnostic before I added
more incaranations of it to the tests.
