I was inconsistently providing initialized or uninitialized memory
to the callback when projecting a settable address, depending on
component type. We should always provide an uninitialized address.
When a computed property returns a generic, the accessor's function
type may involve a type parameter that needs to be resolved using
the key path instruction's substitution map.
We have an optimization in SILCombiner that "inlines" the use of compile-time constant key paths by performing the property access directly instead of calling a runtime function (leading to huge performance gains e.g. for heavy use of @dynamicMemberLookup). However, this optimization previously only supported key paths which solely access stored properties, so computed properties, optional chaining, etc. still had to call a runtime function. This commit generalizes the optimization to support all types of key paths.
I was inconsistently providing initialized or uninitialized memory
to the callback when projecting a settable address, depending on
component type. We should always provide an uninitialized address.
When a computed property returns a generic, the accessor's function
type may involve a type parameter that needs to be resolved using
the key path instruction's substitution map.
We have an optimization in SILCombiner that "inlines" the use of compile-time constant key paths by performing the property access directly instead of calling a runtime function (leading to huge performance gains e.g. for heavy use of @dynamicMemberLookup). However, this optimization previously only supported key paths which solely access stored properties, so computed properties, optional chaining, etc. still had to call a runtime function. This commit generalizes the optimization to support all types of key paths.
If the keypath argument of a keypath access function is a keypath literal instruction, generate the projection inline and remove the access function.
For example, replaces (simplified SIL):
%kp = keypath ... stored_property #Foo.bar
apply %keypath_runtime_function(%root_object, %kp, %addr)
with:
%addr = struct_element_addr %root_object, #Foo.bar
load/store %addr
Currently this only handles stored property patterns.
rdar://problem/36244734
