Raw type Q is represented as a flexible type
Q<B1, ... Bn> .. Q<*, ... *>
where Bi is a representative upper bound of the corresponding ith type
parameter of Q.
When mapping generic signature, JVM takes type arguments of lower bound
(which is 'Q<B1, ..., Bn>').
There is still some difference in how JVM and JVM_IR handle raw type in
signature. It requires additional investigation.
Default implementation of `IrStatement.transform` contained a cast to
`IrStatement`. Since almost all IR elements inherit from IrStatement,
this implementation was used in many subclasses. However, checkcast to
interface is slow and this place was indeed noticeable in the profiler
snapshot. Since not that many places really expected to get IrStatement
out of IrStatement.transform, introduce a new method
`transformStatement` that does this cast, and use it in all those
places. Meanwhile, most implementations will use the IrElement's
implementation of `transform` which merely invokes `accept` without
casts.
Also, inherit IrDeclarationBase from IrElementBase to be able to use a
cast to IrElementBase, which is faster than a cast to IrElement or
IrDeclaration.
IrElementTransformer.visitDeclaration/visitExpression are very prominent
hotspots, and it seems that HotSpot doesn't optimize the inlined Kotlin
bytecode there well enough. Reduce the bytecode in these and similar
methods by inlining calls to also/apply/transformChildrenVoid.
Merge IrMemberAccessExpressionBase into IrMemberAccessExpression, and
IrCallWithIndexedArgumentsBase into IrFunctionAccessExpression (extract
the latter into a separate file).
Implement no-op acceptChildren/transformChildren in the base class
IrExpressionBase instead. This doesn't change behavior because all other
implementations of acceptChildren/transformChildren are not affected.
Do not store these as properties in IrElementBase, IrExpressionBase and
similar classes. This helps to reduce boilerplate in implementations
(just "override val" in the constructor, instead of taking a parameter
and passing it to the superclass), and also slightly optimizes memory in
cases where the value is trivial (UNDEFINED_OFFSET, 0, etc) and thus
does not need to be stored.
For IrProperty, IrSimpleFunction we need to pass information about
original declaration to JVM_IR codegen. Instead of descriptors, use
the attributeOwnerId field.
The main purpose of this class is to improve performance of IR visitors
and transformers. `IrElementVisitor.visitDeclaration` now takes
IrDeclarationBase as a parameter, and therefore the call to `accept`
there is now a virtual class call, instead of an interface call.
Igor Chevdar