SubstitutionMaps are now just a trivial pointer-sized value, so
pass them by value instead.
I did have to move a couple of functors from Type.h to SubstitutionMap.h
to resolve some issues with forward declarations.
Use AccessedStorageAnalysis to find access markers with no nested conflicts.
This optimization analyzes the scope of each access to determine
whether it contains a potentially conflicting access. If not, then it
can be demoted to an instantaneous check, which still catches
conflicts on any enclosing outer scope.
This removes up to half of the runtime calls associated with
exclusivity checking.
Fixed-ABI means that we can do value operations on the type without
any metadata: value-allocations, copies, and destroys. It's currently
equivalent to being fixed-size, but (1) being fixed-size isn't useful
by itself at the SIL level and (2) you can imagine resilience or generics
micro-optimizations where there's like an attribute that tells us the
size of a type without actually telling us how to copy it. All types
are fixed-ABI except:
- layout-unconstrained generic types,
- resilient value types, and
- value types which contain a subobject of such a type (except within
indirect enum cases).
ABI-accessible means that we can perform value operations at all.
We might not be able to if the type is not fixed-ABI and it is private
to a different file (in non-WMO builds) or internal to a different
module, because in such cases we will not be able to access its metadata.
In general, we can't use such types `T` directly, but we may be able to
use types `C` that contain such types as subobjects. Furthermore, we
may be reasonably exposed to SIL that performs operations that treat `C`
as non-opaque, e.g. if `C` is frozen (as it will be by default for
modules in Swift 5). We can still achieve correctness in these cases
as long as we don't either:
- inline code that contains value operations on `T` or
- attempt to recursively expand a value operation on `T` into value
operations on its subobjects.
The SIL optimizer currently never tries to expand value operations on
objects in memory. However, IRGen always recursively expands value
operations on frozen types; that will be fixed in a follow-up patch.
The SIL verification that I've added here is definitely incomplete.
Introduced during the bring-up of the generics system in July, 2012,
Substitution (and SubstitutionList) has been completely superseded by
SubstitutionMap. R.I.P.
SIL optimizations may rewrite profiling intrinsics in a way that IRGen
can't lower (r://39146527). Don't claim that a coverage mapping has a
guaranteed associated symbol table entry when this happens.
I have not added a test, as this is a defensive workaround until we can
land add a SIL verifier check that prevents profiling intrinsics from
being rewritten.
rdar://40133800
This flag supports promoting KeyPath access violations to an error in
Swift 4+, while building the standard library in Swift 3 mode. This is
only necessary as long as the standard library continues to build in
Swift 3 mode. Once the standard library build migrates, it can all be
ripped out.
<rdar://problem/40115738> [Exclusivity] Enforce Keypath access as an error, not a warning in 4.2.
This optimization inserted bit casts based on structural properties of types.
It caused a miscompile in case of imported C structs. Also, by inspection, I found that checks for resilient types are missing.
As this optimization does not have any noticeable impact on the benchmarks it's better to remove it at all, together with the complexity for checking the types.
rdar://problem/40074362
I am doing this for two reasons:
1. I am going to use this in function signature opts to prove that a guaranteed
parameter is "consumed".
2. It puts the ownership verifier on a diet.
rdar://38196046
No major change in execution time, but why make things more
complicated than they need to be? It does make
SILInstructionResultArray::begin drop out of the top ten functions in
the inverted call stack (not counting performLLVM).
In a non-rigorous test, this change shaves off 20% of the time spent
in SIL optimizations for the standard library in a +Asserts build.
(Admittedly the wins for a no-asserts build will be much lower because
SILInstructionResultArray has a bunch of assertions in its
constructor.)
When introducing SIL cloner support for substitution maps, I failed
to account for the separate handling of substitutions for opened
existentials. Perform this substitution when needed.
Fixes rdar://problem/39976572.
Substitution can be expensive; only do it when there might be something to
substitute. While here, use QueryTypeSubstitutionMapOrIdentity rather than
open-coding the same thing in a lambda.
