This bug occurs in real projects, when type aliases are involved.
The test-case is a bit hard to provide. I’ll try to provide it later, if I managed to reduce the original project to a small test-case.
But the fix is very obvious.
Fixes rdar://31768258
- Introduced a new helper class FunctionSignaturePartialSpecializer which provides most of the functionality required for producing a specialized generic signature based on the provided substitutions or requirements. The class consists of many small functions, which should make it easier to understand the code.
- Added a full support for partial specialization of generic parameters with generic substitutions (use flag `-Xllvm -sil-partial-specialization-with-generic-substitutions` to enable it)
- Removed the simpler version of the partial specializer which could partially specialize only generic parameters with non-generic substitutions. It is not needed anymore, because we can handle any substations now when performing the partial specialization.
- The functionality used by the EagerSpecializer to implement the partial specializations required by @_specialize is expressed in terms of FunctionSignaturePartialSpecializer as well. The code implementing it is much smaller now.
Partial specialization of generic parameters with generic substitutions is fully functional, but it is disabled by default, because it needs some tweaks when it comes to compile times and size of produced code. These issues will be addressed in the subsequent commits.
There were two bugs:
- A proper GenericContextScope was not set for type lowering
- Interface types were not mapped to contextual types before using them in SIL instructions
In case of a full specialization, the specialized function does not have a generic signature. Therefore there is no need to build it.
This speeds up the compilation by avoiding doing a useless work.
remapRequirements() was doing a whole lot of substitution work by
itself that the GenericSignatureBuilder is already capable of
doing. Use the GSB's functionality instead.
Rather than true (an error occurred) or false (the constraint was
resolved), introduce ConstraintResult to better model what
happened. NFC for now, but the intent here is to report unresolved
constraints through this mechanism.
Properly cast the result of a devirtualized partial_apply, because this may be required in case of classes implementing protocols. More specifically, it came up when there is a derived class of a class implementing an initializer required by the protocol.
Fixes rdar://31459426 (SR-4501) and rdar://31479426 (SR-3476)
This commit changes how inline information is stored in SILDebugScope
from a tree to a linear chain of inlined call sites (similar to what
LLVM is using). This makes creating inlined SILDebugScopes slightly
more expensive, but makes lowering SILDebugScopes into LLVM metadata
much faster because entire inlined-at chains can now be cached. This
means that SIL is no longer preserve the inlining history (i.e., ((a
was inlined into b) was inlined into c) is represented the same as (a
was inlined into (b was inlined into c)), but this information was not
used by anyone.
On my late 2012 i7 iMac, this saves about 4 seconds when compiling the
RelWithDebInfo x86_64 swift standard library — or 40% of IRGen time.
rdar://problem/28311051
In particular, support the following optimizations:
- owned-to-guaranteed
- dead argument elimination
Argument explosion is disabled for generics at the moment as it usually leads to a slower code.
