Outside of the resilience domain, they have to be treated as opaque and therefore potentially
addressable-for-dependencies, but inside of the resilience domain, we may take advantage of
knowing the type layout to load indirect parameters out of memory and break the (unnecessary)
dependency on a fixed memory location. Fixes rdar://151268401.
We do still however have problems when the type is actually `@_addressableForDependencies`
inside of its resilience domain (rdar://151500074). I'll fix that in a follow up.
This will cause tests today to crash since even though we are placing the
isolation now, to make it easier to read, I left in the old isolation selecting
code. This code uses the witness's isolation instead of the requirement's
isolation which is incorrect since the protocol witness thunk needs to look the
requirement from an ABI perspective since the two must be substitutable. The
crash comes from the ABI verification I added in earlier commits.
Diagnostics only work with `SourceLoc` which is basically a pointer into a buffer of the loaded source file.
But when debug info is de-serialized, the SIL `Location` consists of a filename+line+column.
To "convert" this to a `SourceLoc`, the file must be loaded.
This change adds `DiagnosticEngine.getLocationFromExternalSource` for this purpose.
Also, the new protocol `ProvidingSourceLocation` - to which `SourceLoc` and `Location` conform - help to generalize the helper struct `Diagnostic` and make this "conversion" happen automatically.
Also, make it more tolerant to instructions and builtins, which are not explicitly handled.
This avoids crashes when new instructions are added. We got lucky that this didn't happen so far.
Add a boolean parameter `salvageDebugInfo` to `Context.erase(instruction:)`.
Sometimes it needs to be turned off because the caller might require that after erasing the original instruction the operands no users anymore.
It derives the address of the first element of a vector, i.e. a `Builtin.FixedArray`, from the address of the vector itself.
Addresses of other vector elements can then be derived with `index_addr`.
Instead of passing in the substituted type, we pass in the
InFlightSubstitution. This allows the substituted type to be
recovered if needed, but we can now skip computing it for
the common case of LookUpConformanceInSubstitutionMap.
Add a note explaining that dependence on closure captures is not
supported. Otherwise, the diagnostics are very confusing:
"it depends on a closure capture; this is not yet supported"
This replaces the oddly-named mapIntoTypeExpansionContext() method
on SubstitutionMap itself in favor of a global function, just like
the ones that take Type and ProtocolConformanceRef.
If the method is a default witness methods (`selfType` != nil) it has generic self type.
In this case the generic self parameter is at depth 0 and the actual generic parameters of the substitution map are at depth + 1, e.g:
```
@convention(witness_method: P) <τ_0_0><τ_1_0 where τ_0_0 : GenClass<τ_1_0>.T>
^ ^
self params of substitution map at depth + 1
```
* move it from the SIL to the AST module (where it belongs)
* change the signature of `diagnose` from `diagnose(location, .some_error)` to `diagnose(.some_error, at: location)`
* add an overload to allow passing a `SIL.Location` directly to `diagnose`
* add a `Diagnostic : Error` utility struct which allows throwing a `Diagnostic`
Store specialize witness tables in a separate lookup table in the module. This allows that for a normal conformance there can exist the original _and_ a specialized witness table.
Also, add a boolean property `isSpecialized` to `WitnessTable` which indicates whether the witness table is specialized or not.
