Currently we don't support hoisting ownership instructions.
But the check was missing a store of Optional.none because such a value has no ownership even if the optional is not trivial.
Fixes a SIL verifier crash.
https://github.com/swiftlang/swift/issues/79491
CSE uses OSSA rauw which creates copies and copies that are created to optimize
across borrow scopes are unoptimizable. This PR avoids this situation for now.
An indirect argument (except `@inout_aliasable`) must not alias with another indirect argument.
Now, if we would replace tempAddr with destAddr in
```
apply %f(%tempAddr, %destAddr) : (@in T) -> @out T
```
we would invalidate this rule.
This is even true if the called function does not read from destAddr.
Fixes a SIL verification error.
rdar://145090659
Usage of Span was temporarily behind an experimental feature flag. Now
that SE-0447 has been accepted, remove the experimental feature flag and
allow Span usage everywhere.
Implements rdar://144819992.
Needed to diagnose MutableSpan and OutputSpan.
For now, simply remove the bailout and TODO. The next change will introduce more
logic to force a diagnostic error in rare cases that can't be handled completely.
Fixes rdar://143584461 (Extended exclusive borrow issues with
MutableSpan and OutputSpan)
Functional changes:
Improved modeling of dependence on local variable scopes.
For nested modify->read accesses, only extend the read accesses.
Avoid making a read access dependent on an inout argument.
The following needs to be an error to prevent span storage from being modified:
@lifetime(owner)
foo(owner: inout Owner) -> Span {
owner.span
}
Improve usability of borrowing trivial values (UnsafePointer). Allow:
let span = Span(buffer.baseAddress)
Ignore access scopes for trivial values.
Structural changes:
Delete the LifetimeDependenceUseDefWalker.
Encapsulate all logic for variable introducers within the LifetimeDependenceInsertion pass. Once mark_dependence instructions are inserted, no subsequent pass needs to think about the "root" of a dependence.
Fixes: rdar://142451725 (Escape analysis fails with mutations)
The check is not perfect, because it only checks that the base operand is alive _at_ the mark_dependence.
Ideally it should check that the base operand is alive during the whole lifetime of the value operand.
If the base value of a mark_dependence is an address, that memory location must be initialized at the mark_dependence.
This requires that the mark_dependence is considered to read from the base address.
executing unknown code
This means we have to claw back some performance by recognizing harmless
releases.
Such as releases on types we known don't call a deinit with unknown
side-effects.
rdar://143497196
rdar://143141695
PredictableMemoryAccessOptimizations has become unmaintainable as-is.
RedundantLoadElimination does (almost) the same thing as PredictableMemoryAccessOptimizations.
It's not as powerful but good enough because PredictableMemoryAccessOptimizations is actually only needed for promoting integer values for mandatory constant propagation.
And most importantly: RedundantLoadElimination does not insert additional copies which was a big problem in PredictableMemoryAccessOptimizations.
Fixes rdar://142814676
