...as detected by initializing an individual field without having
initialized the whole object (via `self = value`).
This only applies in pre-Swift-5 mode because the next commit will
treat all cross-module struct initializers as delegating in Swift 5.
Previously in PredMemOpts, we would insert any extracts at the load site, i.e.:
store %foo to %0
...
%1 = struct_element_addr %0, $Type, $Type.field
%2 = load %1
...
apply %use(%2)
would transform to:
store %foo to %0
...
%2 = struct_extract %foo
apply %use(%2)
This framework will not work with Ownership enabled since the value stored is
considered consumed by the store. This change fixes the issue by moving such
non-destructive extracts to occur while %foo is considered live, i.e. before the
store:
%2 = struct_extract %foo
store %foo to %0
...
apply %use(%2)
This means that we have to store insertion points for each store that provides
us with available values and insert the extracts at those points. This creates
some complications in the case where we have multiple stores since we need to
deal with phi nodes. Rather than dealing with it by hand, we just insert the
extracts at each point and then use the SSA updater to insert the relevant phi
nodes.
rdar://31521023
For pred-memopt to work with ownership, we need to insert instructions in two
different places:
1. When loading not-available values, we must insert the load at the site of the
load we are trying to promote.
2. When propagating an available value, we must destructure and or copy before
each one of the stores that provide our value.
By changing AvailableValue to be a struct, I am providing a cleaner API, but
more importantly the ability to start tracking that information.
rdar://31521023
In non-ownership SIL, PMOpt did not need to distinguish in between destructive
and non-destructive sub element extraction. This allowed PMOpt to just use the
"non-destructive" sub element (i.e. extractSubElement) everywhere. In
preparation for introducing this distinction (and a destructive sub element
extractor), rename extractSubElement to be nonDestructivelyExtractSubElement for
clarity.
NFC.
rdar://31521023
And fix it's handling of guaranteed closure contexts.
Guaranteed/unowned captures and guaranteed contexts are *not* released
by a call of the closure.
I assume we have not seen this because we don't see code that would
trigger this comming out of the frontend ...
SR-5441
rdar://33255593
@_silgen_name and @_cdecl functions are assumed to be referenced from
C code. Public and internal functions marked as such must not be deleted
by the optimizer, and their C symbols must be public or hidden respectively.
rdar://33924873, SR-6209
AssignInst is eliminated by DI so we should /never/ see any AssignInst once DI
runs. So this code is dead.
Just shaved off of a larger commit to make it easier to review the larger
commit.
rdar://31521023
This changes code generation a bit, because now the conditional
state bitmap uses a bit to track if the 'self' box was stored,
not if the 'self' value was consumed. In some cases, this
eliminates an extra bit, in other places it introduces an
extra bit, but it really doesn't matter because LLVM will
optimize this bit manipulation easily.
In a throwing or failable initializer for a class, the typical pattern
is that an apply or try_apply consumes the self value, and returns
success or failure. On success, a new self value is produced.
On failure, there is no new self value. In both cases, the original
self value no longer exists.
We used to model this by attempting to look at the apply or try_apply
instruction, and figure out from subsequent control flow which
successor block was the success case and which was the error case.
The error blocks were marked as such, and a dataflow analysis was used
to compute whether 'self' had been consumed in each block reachable
from the entry block.
This analysis was used to prevent invalid use of 'self' in catch
blocks when the initializer delegation was wrapped in do/catch;
more importantly, it was also used to know when to release 'self'
on exit from the initializer.
For example, when we 'throw e' here, 'self' was already consumed
and does not need to be released -- doing so would cause a crash:
do {
try self.init(...)
} catch let e {
// do some other cleanup
throw e
}
On the other hand, here we do have to release 'self', otherwise we
will exit leaking memory:
do {
try someOtherThing()
self.init(...)
} catch let e {
// do some other cleanup
throw e
}
The problem with the old analysis is that it was too brittle and did
not recognize certain patterns generated by SILGen. For example, it
did not correctly detect the failure block of a delegation to a
foreign throwing initializer, because those are not modeled as a
try_apply; instead, they return an Optional value.
For similar reasons, we did not correctly failure blocks emitted
after calls to initializers which are both throwing and failable.
The new analysis is simpler and more robust. The idea is that in the
success block, SILGen emits a store of the new 'self' value into
the self box. So all we need to do is seed the dataflow analysis with
the set of blocks where the 'self' box is stored to, excluding the
initial entry block.
The new analysis is called 'self initialized' rather than 'self
consumed'. In blocks dominated by the self.init() delegation,
the result is the logical not of the old analysis:
- If the old analysis said self was consumed, the new one says self
is not initialized.
- If the old analysis said self was not consumed, the new analysis
says that self *is* initialized.
- If the old analysis returned a partial result, the new analysis
will also; it means the block in question can be reached from
blocks where the 'self' box is both initialized and not.
Note that any blocks that precede the self.init() delegation now
report self as uninitialized, because they are not dominated by
a store into the box. So any clients of the old analysis must first
check if self is "live", meaning we're past the point of the
self.init() call. Only if self is live do we then go on to check
the 'self initialized' analysis.
Support for @noescape SILFunctionTypes.
These are the underlying SIL changes necessary to implement the new
closure capture ABI.
Note: This includes a change to function name mangling that
primarily affects reabstraction thunks.
The new ABI will allow stack allocation of non-escaping closures as a
simple optimization.
The new ABI, and the stack allocation optimization, also require
closure context to be @guaranteed. That will be implemented as the
next step.
Many SIL passes pattern match partial_apply sequences. These all
needed to be fixed to handle the convert_function that SILGen now
emits. The conversion is now needed whenever a function declaration,
which has an escaping type, is passed into a @NoEscape argument.
In addition to supporting new SIL patterns, some optimizations like
inlining and SIL combine are now stronger which could perturb some
benchmark results.
These underlying SIL changes should be merged now to avoid conflicting
with other work. Minor benchmark discrepancies can be investigated as part of
the stack-allocation work.
* Add a noescape attribute to SILFunctionType.
And set this attribute correctly when lowering formal function types to SILFunctionTypes based on @escaping.
This will allow stack allocation of closures, and unblock a related ABI change.
* Flip the polarity on @noescape on SILFunctionType and clarify that
we don't default it.
* Emit withoutActuallyEscaping using a convert_function instruction.
It might be better to use a specialized instruction here, but I'll leave that up to Andy.
Andy: And I'll leave that to Arnold who is implementing SIL support for guaranteed ownership of thick function types.
* Fix SILGen and SIL Parsing.
* Fix the LoadableByAddress pass.
* Fix ClosureSpecializer.
* Fix performance inliner constant propagation.
* Fix the PartialApplyCombiner.
* Adjust SILFunctionType for thunks.
* Add mangling for @noescape/@escaping.
* Fix test cases for @noescape attribute, mangling, convert_function, etc.
* Fix exclusivity test cases.
* Fix AccessEnforcement.
* Fix SILCombine of convert_function -> apply.
* Fix ObjC bridging thunks.
* Various MandatoryInlining fixes.
* Fix SILCombine optimizeApplyOfConvertFunction.
* Fix more test cases after merging (again).
* Fix ClosureSpecializer. Hande convert_function cloning.
Be conservative when combining convert_function. Most of our code doesn't know
how to deal with function type mismatches yet.
* Fix MandatoryInlining.
Be conservative with function conversion. The inliner does not yet know how to
cast arguments or convert between throwing forms.
* Fix PartialApplyCombiner.
This fixes a regression from a previous patch, but it doesn't
fully address <https://bugs.swift.org/browse/SR-5682>, because
we now hit a SILGen crasher with the original test case.
Again, since there's no distinction between an enum initializer that
delegates to 'self.init' from one that assigns to 'self', we can remove
the special handling of enum initializers in the 'root self' case.
Now, 'root self' is only used for designated initializers in classes
with no superclass, and struct initializers that perform memberwise
initialization of stored properties.
This regresses some diagnostics, because the logic for delegating
init diagnostics is missing some heuristics present in the root self
case. I will fix this in a subsequent patch.
Previously protocol extension initializers which called 'self.init' were
considered 'delegating', and ones that assign to 'self' were considered
'root'.
Both have the same SIL lowering so the distinction is not useful, and
removing it simplifies some code.
This allows, for example, an initializer to conditionally assign
to self or call self.init, along different control flow paths.
It also means that it is legal to call self.init() multiple times
in a value type initializer, but this... is fine. The old 'self'
is destroyed.
Fixes <rdar://problem/33137910>.
The culprit here is NSManagedObject subclasses that only have @NSManaged
attributes.
This doesn't affect predictable mem opts since this issue is in the
DIMemoryUseCollector that only affects DI and that I have removed.
rdar://34589327
This replaces the '[volatile]' flag. Now, class_method and
super_method are only used for vtable dispatch.
The witness_method instruction is still overloaded for use
with both ObjC protocol requirements and Swift protocol
requirements; the next step is to make it only mean the
latter, also using objc_method for ObjC protocol calls.
introduce a common superclass, SILNode.
This is in preparation for allowing instructions to have multiple
results. It is also a somewhat more elegant representation for
instructions that have zero results. Instructions that are known
to have exactly one result inherit from a class, SingleValueInstruction,
that subclasses both ValueBase and SILInstruction. Some care must be
taken when working with SILNode pointers and testing for equality;
please see the comment on SILNode for more information.
A number of SIL passes needed to be updated in order to handle this
new distinction between SIL values and SIL instructions.
Note that the SIL parser is now stricter about not trying to assign
a result value from an instruction (like 'return' or 'strong_retain')
that does not produce any.
