Add a case to LifetimeDependence.Scope to support dependencies on address-only
'let' variables. This comes up with C++ interop.
Fixes rdar://147500193 (Spurious lifetime error with closures)
Add support for returnValue phis (e.g. to return an Optional .some or .none).
Fixes rdar://149397018 (Wrapping non escapable in an Optional
(or any copy lifetime wrapper) is an escape)
This allows further extension of access scopes.
Fixes rdar://143992296 (Use of `RawSpan` in switch context causes compiler crash
in AddressOwnershipLiveRange)
Only return false if the visitor returns false. Clients were ignoring the
result.
If the BorrowingOperand does not create a borrow scope, call visitUnknownUse
instead.
Until we have complete lifetimes, to avoid breaking code that cannot handle dead
defs, consider a dead borrow scope to be an unknown use.
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 problem with `is_escaping_closure` was that it didn't consume its operand and therefore reference count checks were unreliable.
For example, copy-propagation could break it.
As this instruction was always used together with an immediately following `destroy_value` of the closure, it makes sense to combine both into a `destroy_not_escaped_closure`.
It
1. checks the reference count and returns true if it is 1
2. consumes and destroys the operand
Record a forwarding mark_dependence as a local access. This is necessary because
we now emit a mark_dependence for @out arguments, which will be the starting
point for diagnostics:
%out = alloc_stack
apply %f(%owned, %out) : $(Owner) -> @lifetime(borrow 0) @out View
%unused = mark_dependence [unresolved] %out on %owner
%dependentValue = load %out
This mark_dependence has no uses. Instead, it simply records the dependency of
the in-memory value on the owner. Consequently, simply walking the uses of
LifetimeDependence.dependentValue does fails to diagnose any escapes. Instead,
if the dependentValue is an address-type mark_dependence, treat it as a local
access to the address that it forwards. Then we find any reachable uses of that
local variable as a potential escape.
Fixes rdar://143040479
(Borrow diagnostics not triggered for @out return values)
Unlike @in, treat @in_guaranteed like a caller-side dependence
scope because there is not need to look for the end of the lifetime in the
current function.
Completely fixes rdar://142847915 (Crash during lifetime checking
while building new swift standard library `Span`-related features)
This encourages AccessPathWalker clients to handle enclosing mark_deps. In
some cases, it is necessary. The accessBaseWithScopes API now provides both
nested begin_access and mark_dependence.
Recognize dependence on the address of a trivial 'var' as an "access" dependence
instead of an "unknown" dependence. This allows the mark_dependence to be
resolved as "[nonescaping]".
This pass rewrites mark_depenendence to ignore "useless" borrow scopes. It was
also accidentally rewriting a dependence on a loaded value, which may redirect the
dependence to the access scope used to load that value. That access scope may be
narrower than the lifetime of the loaded value which could result in invalid
SIL. Do not rewrite this mark_dependence:
%access = begin_access [read] [unknown] %base
%load = load [trivial] %access
end_access %access
%adr = pointer_to_address
%md = mark_dependence [unresolved] %adr on %load
Fixes rdar://142424000 (Swift compiler crashes with Assertion failed
(isa<UnreachableInst>(block->getTerminator())))
Look through a call to the ConvertPointerToPointerArgument compiler intrinsic
just like it is a copy of the pointer. At the source level, that's all it is:
Treat this like a direct use of the argument 'p' rather than the result of the
invisible pointer conversion call:
func foo(_: UnsafeRawPointer)
func bar(p: UnsafePointer<T>) {
foo(p)
}
Add `Value.constantAccessPath`. It is like `accessPath`, but ensures that the projectionPath only contains "constant" elements.
This means: if the access contains an `index_addr` projection with a non-constant index, the `projectionPath` does _not_ contain the `index_addr`.
Instead, the `base` is an `AccessBase.index` which refers to the `index_addr`.
In lazy typechecking mode, errors in the program may only be discovered during
SILGen, which can leave the SIL in a bad state for subsequent stages of
compilation. If errors were detected, skip SIL verification and optimization to
prevent knock-on failures.
Partially reverts https://github.com/swiftlang/swift/pull/75428, which included
a more targeted fix for one of the possible knock-on effects of bad SIL coming
out of SILGen.
Resolves rdar://132107752.
Invalid types are not considered Escapable. This makes it difficult to make any
assumptions about nonescapable types.
Fixes rdar://132348528 (Fix LifetimeDependenceDiagnostics to handle invalid SIL types)
The copy operator has been implemented and doesn't use it. Remove
`Builtin.copy` and `_copy` as much as currently possible.
Source compatibility requires that `_copy` remain in the stdlib. It is
deprecated here and just uses the copy operator.
Handling old swiftinterfaces requires that `Builtin.copy` be defined.
Redefine it here as a passthrough--SILGen machinery will produce the
necessary copy_addr.
rdar://127502242
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.
