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.
The original implementation just printed a mostly information-free message and then went on as if nothing has happened, making it ridiculously easy to write broken code and release it. Changed it to:
* Any VMAbortException will now terminate the game session and go back to the console.
* It will also print a VM stack trace with all open functions, including source file and line numbers pointing to the problem spots. For this the relevant information had to be added to the VMScriptFunction class.
An interesting effect here was that just throwing the exception object increased the VM's Exec function's stack size from 900 bytes to 70kb, because the compiler allocates a separate local buffer for every single instance of the exception object.
The obvious solution was to put this part into a subfunction so that it won't pollute the Exec function's own stack frame. Interesting side effect of this: Exec's stack requirement went down from 900 bytes to 600 bytes. This is still on the high side but already a lot better.
- throw a useful exception when a VM abort occurs, the simple enum was incapable of reporting anything more than the barest minimum, which at least for array index out of bounds errors was insufficient.
The current exception mechanism is still insufficient. It really has to report a proper crash location and print a stack trace to the maximum extent possible. Instead it just prints a message and happily goes on. This is not a good solution.
A few notes:
* this accesses the lines array in sector_t which effectively is a pointer to an array of pointers - a type the parser can not represent. The compiler has no problems with it, so for now it is defined internally.
* array sizes were limited to 65536 entries because the 'bound' instruction only existed as an immediate version with no provisions for larger values. For the static map arrays 65536 is not sufficient so now there are alternative instructions for these cases.
* despite the above, at the moment there is no proper bounds checking for arrays that have no fixed size. To do this, a lot more work is needed. The type system as-is is not prepared for such a scenario.
- fixed: The code generator had no good safeguards for exceeding the maximum amount of registers.
All there was was a handful of pitiful asserts which in production code do nothing at all but generate broken output.
Even worse, the VM was hardwired to at most 255 constants per type per function by storing the constant count in a byte! This has been extended to 65535, but since many instructions only have a byte available for the constant index, a workaround had to be added to do a two-instruction setup if larger indices are needed.
- added new VM instructions to access the constant tables with a variable index.
- refactored VMFunctionBuilder's constant tables so that they are not limited to one entry per value. While this works fine for single values, it makes it impossible to store constant arrays in here.
- fixed code generation for using local variables as array index. This must use a different register for the array element offset because the original register may not be overwritten.
Now even in DECORATE it is possible to report most cases in which user variables are accessed from non-item states as an error. This will report all states which can be traced by a direct link from a special state label. It will not find states that only get used via A_Jump etc.
- Since the number of small allocations here is extremely high this will help a lot to prevent fragmentation and since most nodes are collected up front and this is done when no large resources are being loaded it won't cause heap spikes.
let Emit methods delete FxExpression arrays when they are done.
- For some reason the deletion process does not work 100%, there are always some nodes left behind and so far I haven't found them. This ensures that these arrays do not live any longer than needed.
* use the function build list instead of the function to pass the info. The function is permanent so not the best place for compile-time info.
* pass along the current state index which is needed to calculate the target state.
- fixed: The state index comparison against 0 was broken.
- fixed: Resolving codegen nodes must set the strictness flag per function so that ZSCRIPT and DECORATE are done properly.
- exported thinker iterator and drop item chain to scripting. Unlike its native counterpart the script-side iterator is wrapped into a DObject to allow proper handling for memory management.
- fixed: The VMFunctionBuilder only distinguished between member and action functions but failed on static ones.
- fixed: FxAssign did not add all needed type casts. Except for purely numeric types it will now wrap the expression in an FxTypeCast. Numeric handling remains unchanged for both performance reasons and not altering semantics for DECORATE.
- exported all internal flags as variables to scripting. They still cannot be used in an actor definition.
- make ATAG_STATE the same as ATAG_GENERIC. Since state pointers exist as actual variables they can take both values which on occasion can trigger some asserts.
- gave PClass a bExported flag, so that scripts cannot see purely internal classes. Especially the types like PInt can cause problems.
Todo: we need readonly references to safely expose the actor defaults. Right now some badly behaving code could overwrite them.
- removed the bogus optional value from the first A_Jump argument. A quick test with an older ZDoom revealed that this was never working - and implementing it would make things a lot more complicated, especially error checking in the code generator.
- fixed: The check for insufficient parameters to a function call was missing.
- fixed: Script functions did not receive the function name when being created.
- relaxed the asserts for PARAM_STATE, because the VM knows nothing about ATAG_STATE. Any state variable's content (e.g. Actor.SeeState) will receive ATAG_GENERIC, rather than ATAG_STATE.
- added a 'NeedResult' flag so that certain operations can create shorter code if the result of the expression is not needed. So far only used for postdecrement/increment statements on local variables (which is the most frequent case where this matters.)
- fixed postincrement and decrement for local variables. Due to the result preservation semantics it created faulty code.
Ironically this only requires a very minor change in the calling code and an added member for the VMFunction to tell that code how many parameters to pass.
This change will allow to turn the vast majority of action functions into regular members, the only ones that still need to be an action function are the few that actually use the pointers.
The generated object code can definitely use an optimization pass but that's something left for later when more things are working. Right now it creates one opcode more than necessary for all member accesses (instead of using the offset in the store command it calculates an actual address of the variable in another address register) and can create one too many for non-constant expressions being assigned to local variables (a move between two registers because the emitted expression on the right hand side does not know that it can emit to the actual variable's register.)
- create proper variable data from the function prototype instead of assuming that there's just 3 pointers.
- added a printable name to VMScriptFunction for error output during gameplay in case something goes wrong.
- added a truncation warning to FxIntCast, which only occurs with ZScript, not with DECORATE. FxBoolCast is intentionally left out because it would defeat the reason for this cast type.
* explicitly require passing the owning class when creating it.
* extract self pointer class when adding a variant.
* put the flags on the single variants, we can not fully rule out that they will be 100% identical, if variants ever get allowed.
* Allow PFunction to work without a VMFunction being attached.
* The Variant for a function must store the prototype itself instead of relying on the VMFunction it points to. Otherwise it would not be possible to reference a prototype during compilation of the function because it does not exist yet.
* Give the variant a list of the function's argument's names, because these are also needed to compile the function.
* create an anonymous function symbol when the function gets registered to the builder. At this point we have all the needed information to set it up correctly, but later this is no longer the case. This is the most convenient info to have here because it contains everything that's needed to compile the function in the proper context, so it has to be present when starting compilation.
* added some preparations to implement special handling for weapons and custom inventory items, which can run action functions in another actor's context. This part is not active yet but the basics are present in SetImplicitArgs.
- fixed uninitialized counter variable in DECORATE parser.
- allow dottable_id of xxx.color so that the property parser can parse 'powerup.color'.
- fixed crash with actor replacement in script compiler.
- add the lump number to tree nodes because parts of the property parser need that to make decisions.
- removed test stuff.
- converted inventory.txt, player.txt and specialspot.txt to ZSCRIPT. These were the minimal files required to allow actor.txt to parse successfully.
- removed the converted files from the DECORATE include list so that these are entirely handled by ZSCRIPT now.
* everything related to scripting is now placed in a subdirectory 'scripting', which itself is separated into DECORATE, ZSCRIPT, the VM and code generation.
* a few items have been moved to different headers so that the DECORATE parser definitions can mostly be kept local. The only exception at the moment is the flags interface on which 3 source files depend.
