Like the symbols and the VM functions this is data that is static from startup until shutdown and has no need to be subjected to garbage collection. All things combined this reduces the amount of GC-sensitive objects at startup from 9600 to 600.
Symbols are very easy to manage once they are in a symbol table and there's lots of them so this reduces the amount of work the GC needs to do quite considerably.
After cleaning out compile-time-only symbols there will still be more than 2000 left, one for each function and one for each member variable of a class or struct.
This means more than 2000 object that won't need to tracked constantly by the garbage collector.
Note that loose fields which do occur during code generation will be GC'd just as before.
- removed all pointer declarations to types from the symbols. All types must be placed into the type table which means that they can be considered static.
All non-actors now use PClass exclusively as their type descriptor.
Getting rid of these two classes already removes a lot of obtuse code from the type system, but there's still three more classes to go before a major cleanup can be undertaken.
Removing this variable is needed to remove PClassType and PClassClass as the next step to eliminate all of PClass's subclasses in order to clean up the type system.
- use a memory arena to store flat pointers so that the messed up cleanup can be avoided by deallocating this in bulk.
- added a new SO opcode to the VM to execute a write barrier. This is necessary for all objects that are not linked into one global table, i.e. everything except thinkers and class types.
- always use the cheaper LOS opcode for reading pointers to classes and defaults because these cannot be destroyed during normal operation.
- removed the pointless validation from String.Mid. If the values are read as unsigned the internal validation of FString::Mid will automatically ensure proper results.
If a later module reused an existing name for a different class or struct type, this new name would completely shadow the old one, even in the base files.
Changed it so that each compilation unit (i.e. each ZScript and DECORATE lump) get their own symbol table and can only see the symbol tables that got defined in lower numbered resource files so that later definitions do not pollute the available list of symbols when running the compiler backend and code generator - which happens after everything has been parsed.
Another effect of this is that a mod that reuses the name of an internal global constant will only see its own constant, again reducing the risk of potential errors in case the internal definitions add some new values.
Global constants are still discouraged from being used because what this does not and can not handle is the case that a mod defines a global constant with the same name as a class variable. In such a case the class variable will always take precedence for code inside that class.
Note that the internal struct String had to be renamed for this because the stricter checks did not let the type String pass on the left side of a '.' anymore.
- made PEnum inherit from PInt and not from PNamedType.
The old inheritance broke nearly every check for integer compatibility in the compiler, so this hopefully leads to a working enum implementation.
* completely scriptified DehackedPickup and FakeInventory.
* scriptified all remaining virtual functions of Inventory, so that its inheritance is now 100% script-side.
* scriptified CallTryPickup and most of the code called by that.
- fixed: Passing local variables by reference did not work in the VM.
- ensure that actor defaults contain a valid virtual table and class pointer so that they can actually use virtual and class-dependent method functions. This is needed for retrieving script variables from them.
- support transient object member variables for information that does not need to be put in a savegame.
- fixed: special initialization of objects needs to pass the proper defaults along, otherwise the parent classes will use their own, inappropriate one.
This was done to ensure it can be properly overridden in scripts without causing problems when called during engine shutdown for the type and symbol objects the VM needs to work and to have the scripted version always run first.
Since the scripted OnDestroy method never calls the native version - the native one is run after the scripted one - this can be simply skipped over during shutdown.
There are a few which require explicit native construction or destruction that need to be exported to the VM, e.g. FCheckPosition.
The VM cannot handle this directly, it needs two special functions to be attached to handle such elements.
- created script exports for all relevant functions with all integral types.
- created script side definitions for the underlying data types.
- added a void pointer type so that the prototype for the pointer array can use a generic type every pointer can be assigned to.
- added a String class to allow attaching methods to the builtin string type. This works by checking if the left side of the member accessor is a string and just replacing the tyoe in this one place, all the rest is automatic.
Needless to say, this is simply too volatile and would require constant active maintenance, not to mention a huge amount of work up front to get going.
It also hid a nasty problem with the Destroy method. Due to the way the garbage collector works, Destroy cannot be exposed to scripts as-is. It may be called from scripts but it may not be overridden from scripts because the garbage collector can call this function after all data needed for calling a scripted override has already been destroyed because if that data is also being collected there is no guarantee that proper order of destruction is observed. So for now Destroy is just a normal native method to scripted classes
- added new VARF_Transient flag so that the decision whether to serialize a field does not depend solely on its native status. It may actually make a lot of sense to use the auto-serializer for native fields, too, as this would eliminate a lot of maintenance code.
- defined (u)int8/16 as aliases to the byte and short types (Can't we not just get rid of this naming convention already...?)
- exporting the fields of Actor revealed a few name clashes between them and some global types, so Actor.Sector was renamed to CurSector and Actor.Inventory was renamed to Actor.Inv.
- added a new type 'NativeStruct'. This will be used for types that cannot be instantiated, and is also needed to cleanly handle many internal types that only can exist as reference.
- changed Dehacked weapon function lookup to check the symbol table instead of directly referencing the VM functions. Once scriptified these pointers will no longer be available.
- removed all special ATAGs from the VM. While well intentioned any pointer tagged with them is basically unusable because it'd trigger asserts all over the place.
- scriptified A_Punch for testing pass-by-reference parameters and stack variables.
- instead add a list of SpecialInits to VMScriptFunction so this can be done transparently when setting up and popping the stack frame. The only drawback is that this requires permanent allocation of stack objects for the entire lifetime of a function but this is a relatively small tradeoff for significantly reduced maintenance work throughout.
- removed most #include "vm.h", because nearly all files already pull this in through dobject.h.
This could cause problems with functions that take states as parameters but use them to set them internally instead of passing them through the A_Jump interface back to the caller, like A_Chase or A_LookEx.
This required some quite significant refactoring because the entire state resolution logic had been baked into the compiler which turned out to be a major maintenance problem.
Fixed this by adding a new builtin type 'statelabel'. This is an opaque identifier representing a state, with the actual data either directly encoded into the number for single label state or an index into a state information table.
The state resolution is now the task of the called function as it should always have remained. Note, that this required giving back the 'action' qualifier to most state jumping functions.
- refactored most A_Jump checkers to a two stage setup with a pure checker that returns a boolean and a scripted A_Jump wrapper, for some simpler checks the checker function was entirely omitted and calculated inline in the A_Jump function. It is strongly recommended to use the boolean checkers unless using an inline function invocation in a state as they lead to vastly clearer code and offer more flexibility.
- let Min() and Max() use the OP_MIN and OP_MAX opcodes. Although these were present, these function were implemented using some grossly inefficient branching tests.
- the DECORATE 'state' cast kludge will now actually call ResolveState because a state label is not a state and needs conversion.
The proper setup for such classes was only done in CreateDerivedClass, but not in FindClassTentative itself. This extends CreateDerivedClass to allow it to create a class without fully initializing it.
Syntax-wise I chose to make it as strict as possible to reduce the chance of errors: Virtual base functions must be declared with the 'virtual' keyword, and overrides in child classes with the 'override' keyword. This way any mismatch in parameters that otherwise would cause silent failure will outright produce a compile error.
- made 'DamageMultiply' an actor property and moved the initialization of ConversationRoot to the property handler for the compiler to get this stuff out of the type classes.
- consolidate default initialization into one function which performs all the required setup. The original implementation did this when adding the fields but that cannot work because at that time no defaults have been created yet.
- fixed: When deriving a class the child class's defaults also must initialize the copied parent fields with special initialization. This part was completely missing.
- removed DECORATE code for parsing native classes because it's no longer needed.
