So, I overlooked this reading the 1.45 documentation, but the first thing they did is completely change f64 conversions. Apparantly, what I was doing (and what JavaScript spec dictates) is actually considered UB in LLVM, and my ability to actually write a concise wrapping u32 conversion is actually a soundness hole in Rust. Ergo, I'm now emulating the wrapping and sign calculation, which makes this both passing it's tests again and free of soundness holes and UB.
I don't know why I'm doing this - tests are failing in CI but not locally, and I can only assume that the most obvious conversion is broken in some way on whatever other architecture GitHub Actions uses. This will explicitly mask the integer result as a u64, and then convert it down to u32. A not-broken compiler should treat this code identically.
AVM2 is based on ES4, which as far as I'm aware, does not distinguish between "primitive values" and "objects". Thus, it is expedient to interpret any statement requiring something to be an Object to mean "not null or undefined".
Since we internally represent register values with primitive types, it is important that the VM always coerces to object before doing any other sort of type checking. Hence, something like `as_object` is unhelpful as it accidentally enforces a primitive/object distinction that ES4 attempted to remove.
Note that this does NOT completely test the full range of if instructions for abstract relational comparison. Notably, the Adobe Animate CC compiler compiles each operator into it's negated equivalent, e.g. `<` becomes `ifnlt`.
I do not know how to get it to emit `ifge` or the like, which differ only by how they handle `NaN`s.
The test is also far more in-depth than the `if_eq`/`if_ne` tests, which use the same set of vectors as the strict-equality tests from a while ago. Interestingly, this test passed on first run
Implementation is limited to generating exceptions on `null` or `undefined`. I'm not sure if primitive values don't exist in AVM2 or if this is supposed to box them like ES3, so I have decided to handle neither at this time.
This code is slightly over/under-precise compared to AVM2. This is because we handle precision limiting in binary floats rather than as part of the float printing process. Flash Player may also be rounding differently than us. However, I'm pretty sure ECMA-262 allows us to slightly differ here.
The ECMA-262 documentation is awfully overwrought for something that boils down to "chop off the non-whole part, wrap to 32 bits, then reinterpret as signed". Bitwise operations are *hell* to describe mathematically, and such descriptions are even harder to understand.
For whatever reason, `pushbyte` appears to be processed as a *signed* byte, despite the clear wording of "*byte_value* is an unsigned byte" in avm2overview.pdf. I guess it's supposed to be manually converted and promoted in this manner.
As compiled by Adobe Animate CC 2020, this test appears to only use `iffalse`. However, both `op_is_false` and `op_is_true` coerce in the same manner, so I'm not entirely sure this is a problem for now.
Functions that need to assert Boolness without coercion should either:
1. Ensure their function declaration requires a Boolean. (We don't enforce type errors on ES4 typehints yet, but we should.)
2. Check the value type themselves and raise their own errors if necessary.
As it stands the only users of `as_bool` either needed to check the type themselves or use `coerce_to_bool`. Notably, `setPropertyIsEnumerable` doesn't appear to coerce *or* throw an error: it instead fails silently if you hand it a non-`Boolean` value.
Notably, all of the `Avm1` "run stack frame" functions can no longer take a self parameter as the update context they will be getting also has that same parameter. Ergo, they're associated functions that get the moral equivalent of self from the update context.
This also introduces a new `Activation::from_stub` which creates a stub frame that runs everything on the main movie in layer 0. This significantly reduces boilerplate code elsewhere in the project.
This also removes the function parameter on `sort_compare_numeric`. As it was only being used for string comparisons, and it was causing unfixable lifetime issues, I have instead had it take the case-sensitivity flag and call the two functions it would have been passed anyway. This fixes the lifetime issue.
The process of constructing an `Activation` now involves calling `UpdateContext.reborrow`, which "sheds" a lifetime by copying all of the borrows into a new "owned" context with that lifetime.
Likewise, to call out to functions that don't need an `Activation`, just borrow the context out of the current activation. You can also construct child-frame activations by reborrowing the parent activation's context.
There is a race condition inadvertently caused by allowing movies to be fetched in slot 0: it is possible for the player to be caught mid-load without a root movie. A lot of code assumes level 0 always exists (e.g. `levels.get(0).unwrap()`), while our initialization methods assumed no Player methods would be called until the root movie is installed. This is an unreasonable assumption, as among other things users can trigger the race condition by just playing the movie too quickly.
This allows us to remove the conditionals on implementations of `from_path` that need to call this function, as the function is now always guaranteed to be there, even if it's just a no-op/`Err` generator.
During the small period of time when a player is created but has no root movie, a temporary empty movie is installed with an assumed stage size and framerate of 550x400@12fps. This is Flash default for new projects, so it seemed appropriate. User ActionScript cannot see these values, and I'm not even sure JavaScript can, either.
Calling loadMovieNum with a variable parameter compiles into a
GetURL2 call with a `_level` window target parameter. Previously
this triggered Ruffle to try to navigate to the SWF. Now it
properly loads the SWF inside the current movie.
Holding a `Ref` on a garbage-collected object inherently extends any borrow locks on that object. Since ABC files are references already, taking a `Ref` to them only helps to skip the refcount update. This is less useful than expected: in most situations, using `abc_ref` causes double-borrow panics. The few methods that can use it are going to be fragile in the face of future refactors, so I'm nipping the problem in the bud now.
For good measure, most of the other methods in `value` for retrieving pool primitives now also use `TranslationUnit` instead of `AbcFile`. This is the result of a handful of cascading changes throughout the project, and itself caused a few more.
Interface methods are specifically not allowed to be called: as a result, they don't get a method body. Existing code assumed a 1:1 relationship between methods and bodies, which causes spurious errors.
This is inspired by Dinnerbone's similar PR on the AVM1 side, where the Action half of that VM's `Executable` was reduced from 128 bytes to 16 by shoving it in a `Gc`. This won't be as dramatic but should still save some memory.
In fact, it should save a *lot* of memory in bytecode execution, where thanks to the previous commit's rebase, we now need to clone the current method once *for each instruction executed*. That is terrible, but should stop now.
This also results in a far reduced role for `ReturnValue`, since I also took the liberty of removing most of it's use. Furthermore, I also made it apply equally to native and AVM2 code, which ensures all native implementations of methods don't double-borrow.
In AVM1, `ReturnValue` was actually removed entirely, because it's not needed. I attempted to do the same, but the fact that we're currently embedding `ScriptObjectData` in native objects means that we need it for virtual properties. Otherwise, virtual property implementations will see locked objects, which is bad.
While some code that references pool multinames has zero as a valid index, we cannot validate exactly what the zero index is for a given index. Hence, callers instantiating multinames must check for zero and substitute the correct zero-value interpretation for their given type. If zero is an invalid value, it should ideally throw a different error than what's provided here.
This commit breaks the build: we still need to tell `Avm2` how to turn ABC traits into our own internal `Trait<'gc>`, `Class<'gc>`, and `Method<'gc>` types. We also need something to track which traits have already been instantiated, because `callstatic` would otherwise reinstantiate the trait in a different scope. (In fact, I think it *does* do exactly that right now...)
The intention is to completely replace all usage of `Avm2XYZEntry` with `Class`, `Trait`, and `Method`. This will allow runtime-provided global class traits to coexist with those provided by user code.
Inspired by Dinnerbone's PR doing the exact same thing to AVM1.
On AVM2 we have a bit of a subtle issue: the base implementation of `set_property_local` and `init_property_local` *must* return `ReturnValue`s to avoid double-borrows. Each implementation of `TObject` must resolve them before returning.
This function has vague documentation about enabling locale-specific formatting in subclasses. As far as I can tell, none of the objects I implemented so far do anything different than `toString`, so I just have it use the same `TObject` property I set up for `toString`.
This was originally something *way* more evil: mixed inheritance between ES3 and ES4 classes. It didn't pan out due to fundamental limitations of the two object models. How the hell did Brendan Eich/Adobe/TC-39 expect ES4 classes to be adopted in already-existing codebases?!
We still reuse the `FunctionObject` machinery internally. If necessary, we may want to split this into a separate `ClassObject` if some internal `TObject` method needs replacing for classes.
In practice not many movies will care about this, because the `AS3` namespace is open by default. You could opt-out of that, and I suppose that was there for using existing ES3 code in AS3 projects. ES4 would have had a similar ES4 namespace, which "JavaScript 2.0" code would need to opt into. Of course, ES4/JS2 never happened, so we just have this weird historical quirk here.
The reason for this is that, in AVM2, `toString` and `valueOf` are not defined on the classes or prototypes of `Function` or `Class`. Instead, they use the `Object.prototype` versions of those functions. Ergo, string and primitive coercion are inherent object methods (the ones that get `[[DoubleSquareBrackets]]` in the ECMA standards). In Ruffle, our equivalent to `[[DoubleSquareBrackets]]` methods are methods on the `TObject` trait, so we're adding them there.
This mechanism will make implementing boxed value types (ala AVM1's `BoxedObject`) easier, too.
We also add some reasonable defaults for `ScriptObject` and `FunctionObject` which will appear on objects, functions, and classes.