Try to do as few checks as possible. Check for builtin types only once,
then look at the BuiltinType Kind. For integers, we cache the int and
long size, since those are used a lot and the ASTContext::getIntWidth()
call is costly.
The Pointer class already has the capability to be a function pointer,
but we still classifed function pointers as PT_FnPtr/FunctionPointer.
This means when converting from a Pointer to a FunctionPointer, we lost
the information of what the original Pointer pointed to.
Create the Function* handles for all functions we see, but delay the
actual compilation until we really call the function. This speeds up
compile times with the new interpreter a bit.
This is unneeded in almost all circumstances. We only return an APValue
back to clang when the evaluation is finished, and that is always done
by an EvalEmitter - which has its own implementation of the Ret
instructions.
The global scope we create when evaluating expressions might free some
of the dynamic memory allocations, so we can't check for memory leaks
before destroying it.
I started out by adding a new pointer type for blocks, and I was fully
prepared to compile their AST to bytecode and later call them.
... then I found out that the current interpreter doesn't support
calling blocks at all. So we reuse `Function` to support sources other
than `FunctionDecl`s and classify `BlockPointerType` as `PT_FnPtr`.
This happens for enum types with bool parent types. isBooleanType()
returns false for them however.
The previous version did the same thing by re-classifying the enum
integer type, but that breaks with forward-declared enums.
