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2023-09-22 r/6624 docs(tvix/eval): fix some broken docstr referencesFlorian Klink1-2/+3
There's some more left, but they've been renamed/refactored out of sight. Change-Id: I41579dedc74342b4c5f8cb39d2995b5b0c90b0f4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/9372 Tested-by: BuildkiteCI Reviewed-by: Connor Brewster <cbrewster@hey.com> Autosubmit: flokli <flokli@flokli.de>
2023-06-15 r/6308 fix(tvix/eval): make tvix display values like nix-instantiate(1)sterni1-2/+2
In order for the test suite we have currently to be comparable to C++ Nix, we need to display values in the same way. This was largely the case except in some weird cases. * <CODE> for thunks and <CYCLE> for repeated thunks (?) are already in use. <CODE> formatting is tested by the oracle test suite already. * Instead of lambda, we need to use <LAMBDA> * <<primop>> and <<primop-app>> (a formatting C++ Nix uses nowhere) now are <PRIMOP> and <PRIMOP-APP>. We'll probably want to have a fancier display of values (in a separate trait) down the line. This could be used for interactive usage, e.g. the REPL or a potential debugger. There is a peculiarity with C++ Nix 2.3 formatting primops: import is considered a <<PRIMOP-APP>>, since it is internally implemented by means of scopedImport. This implementation detail no longer leaks in C++ Nix 2.13 nor in Tvix. <CYCLE> display is untested at the moment, since we exhibit a discrepancy to C++ Nix 2.3. Our current detection is more similar to C++ Nix 2.13—luckily it is also the more consistent of the two. See also b/245. Change-Id: I1d534434b02e470bf5475b3758920ea81e3420dc Reviewed-on: https://cl.tvl.fyi/c/depot/+/8760 Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2023-03-13 r/5978 feat(tvix/eval): give generators human-readable namesVincent Ambo1-2/+2
This adds static strings to generator frames that describe the generator in a human-readable fashion, which are then logged in observers. This makes runtime traces very precise, explaining exactly what is being requested from where. Change-Id: I695659a6bd0b7b0bdee75bc8049651f62b150e0c Reviewed-on: https://cl.tvl.fyi/c/depot/+/8206 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 r/5964 refactor(tvix/eval): flatten call stack of VM using generatorsVincent Ambo1-39/+39
Warning: This is probably the biggest refactor in tvix-eval history, so far. This replaces all instances of trampolines and recursion during evaluation of the VM loop with generators. A generator is an asynchronous function that can be suspended to yield a message (in our case, vm::generators::GeneratorRequest) and receive a response (vm::generators::GeneratorResponsee). The `genawaiter` crate provides an interpreter for generators that can drive their execution and lets us move control flow between the VM and suspended generators. To do this, massive changes have occured basically everywhere in the code. On a high-level: 1. The VM is now organised around a frame stack. A frame is either a call frame (execution of Tvix bytecode) or a generator frame (a running or suspended generator). The VM has an outer loop that pops a frame off the frame stack, and then enters an inner loop either driving the execution of the bytecode or the execution of a generator. Both types of frames have several branches that can result in the frame re-enqueuing itself, and enqueuing some other work (in the form of a different frame) on top of itself. The VM will eventually resume the frame when everything "above" it has been suspended. In this way, the VM's new frame stack takes over much of the work that was previously achieved by recursion. 2. All methods previously taking a VM have been refactored into async functions that instead emit/receive generator messages for communication with the VM. Notably, this includes *all* builtins. This has had some other effects: - Some test have been removed or commented out, either because they tested code that was mostly already dead (nix_eq) or because they now require generator scaffolding which we do not have in place for tests (yet). - Because generator functions are technically async (though no async IO is involved), we lose the ability to use much of the Rust standard library e.g. in builtins. This has led to many algorithms being unrolled into iterative versions instead of iterator combinations, and things like sorting had to be implemented from scratch. - Many call sites that previously saw a `Result<..., ErrorKind>` bubble up now only see the result value, as the error handling is encapsulated within the generator loop. This reduces number of places inside of builtin implementations where error context can be attached to calls that can fail. Currently what we gain in this tradeoff is significantly more detailed span information (which we still need to bubble up, this commit does not change the error display). We'll need to do some analysis later of how useful the errors turn out to be and potentially introduce some methods for attaching context to a generator frame again. This change is very difficult to do in stages, as it is very much an "all or nothing" change that affects huge parts of the codebase. I've tried to isolate changes that can be isolated into the parent CLs of this one, but this change is still quite difficult to wrap one's mind and I'm available to discuss it and explain things to any reviewer. Fixes: b/238, b/237, b/251 and potentially others. Change-Id: I39244163ff5bbecd169fe7b274df19262b515699 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8104 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Reviewed-by: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI
2023-02-03 r/5832 refactor(tvix/eval): wrap `Builtin` type in a BoxVincent Ambo1-20/+30
This reduces the size of `Builtin` from 88 (!) bytes to 8, and as the largest variant of `Value`, the size of that type from 96 to 64. The next largest type is NixList, clocking in at 64 bytes. This has noticeable performance impact. In an implementation without disk I/O, evaluating nixpkgs.stdenv looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.151 s ± 0.003 s [User: 1.041 s, System: 0.109 s] Range (min … max): 1.147 s … 1.155 s 10 runs After this change, it looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.046 s ± 0.004 s [User: 0.954 s, System: 0.092 s] Range (min … max): 1.041 s … 1.053 s 10 runs Change-Id: I5ab7cc02a9a450c0227daf1f1f72966358311ebb Reviewed-on: https://cl.tvl.fyi/c/depot/+/8027 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2022-11-08 r/5269 feat(tvix/eval): Add docstrings as documentation for builtinsGriffin Smith1-0/+8
Add a new `documentation: Option<&'static str>` field to Builtin, and populate it in the `#[builtins]` macro with the docstring of the builtin function, if any. Change-Id: Ic68fdf9b314d15a780731974234e2ae43f6a44b0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7205 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-11-08 r/5268 feat(tvix/eval): Give names to builtin argumentsGriffin Smith1-9/+15
Refactor the arguments of a Builtin to be a vec of a new BuiltinArgument struct, which contains the old strictness boolean and also a static `name` str - this is automatically determined via the ident for the corresponding function argument in the proc-macro case, and passed in in the cases where we're still manually calling Builtin::new. Currently this name is unused, but in the future this can be used as part of a documentation system for builtins. Change-Id: Ib9dadb15b69bf8c9ea1983a4f4f197294a2394a6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7204 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-06 r/5040 refactor(tvix/eval): builtins now contain closuresVincent Ambo1-7/+15
For some upcoming builtins (notably, import) we need to capture arguments in the builtin's implementation. To allow this, we can no longer use function pointers for builtins, but must use a reference-counted closure object instead. Unfortunately this adds an extra pointer operation to every builtin call. We should benchmark this later against having a split builtin representation. Change-Id: I109d98d0e25998870542f47573eb1ec2e546f2a2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6856 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-19 r/4918 refactor(tvix/eval): handle forcing in Builtin::applysterni1-4/+12
Instead of arity, we pass a array reference to Builtin::new that describes how many arguments there are and which of them need to be forced, eliminating the need to force manually. Note that this change doesn't fix some of the instances where the the Builtin doesn't consider that the value could be a Thunk. Change-Id: Iadb58bb79886c30dc6b09dcf0ffad8abf28036a1 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6662 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-09-18 r/4908 refactor(tvix/eval): Don't (ab)use PartialEq for Nix equalityGriffin Smith1-0/+7
Using rust's PartialEq trait to implement Nix equality semantics is reasonably fraught with peril, both because the actual laws are different than what nix expects, and (more importantly) because certain things actually require extra context to compare for equality (for example, thunks need to be forced). This converts the manual PartialEq impl for Value (and all its descendants) to a *derived* PartialEq impl (which requires a lot of extra PartialEq derives on miscellanious other types within the codebase), and converts the previous nix-semantics equality comparison into a new `nix_eq` method. This returns an EvalResult, even though it can't currently return an error, to allow it to fail when eg forcing thunks (which it will do soon). Since the PartialEq impls for Value and NixAttrs are now quite boring, this converts the generated proptests for those into handwritten ones that cover `nix_eq` instead Change-Id: If3da7171f88c22eda5b7a60030d8b00c3b76f672 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6650 Autosubmit: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-09-10 r/4786 fix(tvix/eval): fix doc comment syntax where applicableVincent Ambo1-1/+1
As pointed out by grfn on cl/6091 Change-Id: I28308577b7cf99dffb4a4fd3cc8783eb9ab4d0d6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6460 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-08 r/4744 refactor(tvix/eval): pass a VM reference to builtinsVincent Ambo1-4/+14
This makes it possible for builtins to force values on their own, without the VM having to apply a strictness mask to the arguments first. Change-Id: Ib49a94e56ca2a8d515c39647381ab55a727766e3 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6411 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-08 r/4741 feat(tvix/eval): ensure all errors always carry a spanVincent Ambo1-3/+3
Previously error spans were optional because the information about code spans was not available at runtime. Now that this information has been added, the error type will always carry a span. This change is very invasive all throughout the codebase. This is due to the fact that many functions that are called *by* the VM expected to return `EvalResult`, but this no longer works as the span information is not available to those functions - only to the VM itself. To work around this the majority of these functions have been changed to return `Result<T, ErrorKind>` instead and an accompanying macro in the VM constructs the "real" error. Note that this implementatino currently has a bug where errors occuring within thunks will yield the location at which the thunk was forced, not the location at which the error occured within the code. This will be fixed soon, but the commit is large enough as is. Change-Id: Ib1ecb81a4d09d464a95ea7ea9e589f3bd08d5202 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6408 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-03 r/4608 fix(tvix/eval): address all current clippy lintsVincent Ambo1-1/+1
Change-Id: I758fc4f3b9078de7ca6228a75a4351c3e085c4cf Reviewed-on: https://cl.tvl.fyi/c/depot/+/6272 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-02 r/4588 feat(tvix/eval): introduce mechanism for defining builtinsVincent Ambo1-0/+13
Adds a new builtins module in which builtins can be constructed. The functions in this module should return a correctly structured value to be passed to the compiler's `globals`. This is wired up all the way to the compiler with an example `toString` builtin, available as a global. Note that this does not yet actually behave like the real toString, which has some differences from `Display`. Change-Id: Ibb5f6fbe6207782fdf2434435567fc1bd80039a5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6254 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4585 feat(tvix/eval): add initial representation of builtinsVincent Ambo1-0/+66
Builtins are represented as a Rust function pointer that accepts a vector of arguments, which represents variable arity builtins. Change-Id: Ibab7e662a646caf1172695d876d2f55e187c03dd Reviewed-on: https://cl.tvl.fyi/c/depot/+/6251 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>