Although nonescaping closures are representationally trivial pointers to their
on-stack context, it is useful to model them as borrowing their captures, which
allows for checking correct use of move-only values across the closure, and
lets us model the lifetime dependence between a closure and its captures without
an ad-hoc web of `mark_dependence` instructions.
During ownership elimination, We eliminate copy/destroy_value instructions and
end the partial_apply's lifetime with an explicit dealloc_stack as before,
for compatibility with existing IRGen and non-OSSA aware passes.
My goal was to reduce the size of SILLocation. It now contains only of a storage union, which is basically a pointer and a bitfield containing the Kind, StorageKind and flags. By far, most locations are only single pointers to an AST node. For the few cases where more data needs to be stored, this data is allocated separately: with the SILModule's bump pointer allocator.
While working on this, I couldn't resist to do a major refactoring to simplify the code:
* removed unused stuff
* The term "DebugLoc" was used for 3 completely different things:
- for `struct SILLocation::DebugLoc` -> renamed it to `FilePosition`
- for `hasDebugLoc()`/`getDebugSourceLoc()` -> renamed it to `hasASTNodeForDebugging()`/`getSourceLocForDebugging()`
- for `class SILDebugLocation` -> kept it as it is (though, `SILScopedLocation` would be a better name, IMO)
* made SILLocation more "functional", i.e. replaced some setters with corresponding constructors
* replaced the hand-written bitfield `KindData` with C bitfields
* updated and improved comments
...and avoid reallocation.
This is immediately necessary for LICM, in addition to its current
uses. I suspect this could be used by many passes that work with
addresses. RLE/DSE should absolutely migrate to it.
This name makes it clear that the function has not yet been deleted and also
contrasts with the past tense used in the API notifyAddedOrModifiedFunction to
show that said function has already added/modified the function.
The name notifyAddFunction is actively harmful since the pass manager uses this
entrypoint to notify analyses of added *OR* modified functions. It is up to the
caller analysis to distinguish in between these cases.
I am not vouching for the design, just trying to make names match the
current behavior.
Generally in the SIL/SILOptimizer libraries we have been putting kinds in the
swift namespace, not a nested scope in a type in swift (see ValueKind as an
example of this).
Make the static enforcement of accesses in noescape closures stored-property
sensitive. This will relax the existing enforcement so that the following is
not diagnosed:
struct MyStruct {
var x = X()
var y = Y()
mutating
func foo() {
x.mutatesAndTakesClosure() {
_ = y.read() // no-warning
}
}
}
To do this, update the access summary analysis to summarize accesses to
subpaths of a capture.
rdar://problem/32987932
Make the static enforcement of accesses in noescape closures stored-property
sensitive. This will relax the existing enforcement so that the following is
not diagnosed:
struct MyStruct {
var x = X()
var y = Y()
mutating
func foo() {
x.mutatesAndTakesClosure() {
_ = y.read()
}
}
}
To do this, update the access summary analysis to be stored-property sensitive.
rdar://problem/32987932
IndexTrie is a more light-weight representation and it works well in this case.
This requires recovering the represented sequence from an IndexTrieNode, so
also add a getParent() method.
Add an interprocedural SIL analysis pass that summarizes the accesses that
closures make on their @inout_aliasable captures. This will be used to
statically enforce exclusivity for calls to functions that take noescape
closures.
The analysis summarizes the accesses on each argument independently and
uses the BottomUpIPAnalysis utility class to iterate to a fixed point when
there are cycles in the call graph.
For now, the analysis is not stored-property-sensitive -- that will come in a
later commit.
