* add missing APIs
* bridge the entries as values and not as pointers
* add lookup functions in `Context`
* make WitnessTable.Entry.Kind enum cases lower case
This makes ManagedBuffer available and usable in Embedded Swift, by:
- Removing an internal consistency check from ManagedBuffer that relies on metatypes.
- Making the .create() API transparent (to hoist the metatype to the callee).
- Adding a AllocRefDynamicInst simplification to convert `alloc_ref_dynamic` to `alloc_ref`, which removes a metatype use.
- Adding tests for the above.
Usually there _must_ be a read from a consuming in-argument, because the function has to consume the argument.
But in the special case if all control paths end up in an `unreachable`, the consuming read might have been dead-code eliminated.
Therefore make sure to add the read-effect in any case. Otherwise it can result in memory lifetime failures at a call site.
fixes a memory lifetime failure
rdar://134881045
Do this even if the function then contains references to other functions with wrong linkage. Instead fix the linkage later.
Fixes a false error in embedded swift.
rdar://134352676
Make SILLInkage available in SIL as `SIL.Linkage`.
Also, rename the misleading Function and GlobalVariable ABI `isAvailableExternally` to `isDefinedExternally`
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.
The main changes are:
*) Rewrite everything in swift. So far, parts of memory-behavior analysis were already implemented in swift. Now everything is done in swift and lives in `AliasAnalysis.swift`. This is a big code simplification.
*) Support many more instructions in the memory-behavior analysis - especially OSSA instructions, like `begin_borrow`, `end_borrow`, `store_borrow`, `load_borrow`. The computation of end_borrow effects is now much more precise. Also, partial_apply is now handled more precisely.
*) Simplify and reduce type-based alias analysis (TBAA). The complexity of the old TBAA comes from old days where the language and SIL didn't have strict aliasing and exclusivity rules (e.g. for inout arguments). Now TBAA is only needed for code using unsafe pointers. The new TBAA handles this - and not more. Note that TBAA for classes is already done in `AccessBase.isDistinct`.
*) Handle aliasing in `begin_access [modify]` scopes. We already supported truly immutable scopes like `begin_access [read]` or `ref_element_addr [immutable]`. For `begin_access [modify]` we know that there are no other reads or writes to the access-address within the scope.
*) Don't cache memory-behavior results. It turned out that the hit-miss rate was pretty bad (~ 1:7). The overhead of the cache lookup took as long as recomputing the memory behavior.
It's dangerous to continue walking over an `unchecked_addr_cast` which casts between two different types.
We can only do this if the result is known to be the end of the walk, i.e. the cast result is not used in a relevant way.
