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2023-02-04 r/5837 fix(tvix/eval): fix the default case for path parsingVincent Ambo1-10/+4
Plain paths like `foo/bar.nix` are also allowed, so we can not determine this based on the prefix. The upstream PR that is referenced in a comment here has a significantly different interface than we expected, so I'm not touching that comment yet in this CL before I've had more time to digest it. Change-Id: Iea33bbb35de9c00a7d7fedf64d02253c75c1cc9e Reviewed-on: https://cl.tvl.fyi/c/depot/+/8032 Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: Alyssa Ross <hi@alyssa.is> Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-02-03 r/5831 refactor(tvix/eval): statically resolve select from constant attrsVincent Ambo2-40/+90
When resolving a select expression (`attrs.name` or `attrs.name or default`), if the set compiles to a constant attribute set (as is most notably the case with `builtins`) we can backtrack and replace that attribute set directly with the compiled value. For something like `builtins.length`, this will directly emit an `OpConstant` that leaves the `length` builtin on the stack. Change-Id: I639654e065a06e8cfcbcacb528c6da7ec9e513ee Reviewed-on: https://cl.tvl.fyi/c/depot/+/7957 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-02-03 r/5828 fix(tvix/eval): ensure all evaluated thunks are correctly memoizedVincent Ambo1-2/+2
This fixes a very complicated bug (b/246). Evaluation progresses *much* further after this, leading to several less complicated bugs likely being uncovered by this What was the problem? ===================== Previously, when evaluating a thunk, we had a code path that looked like this: match *thunk { ThunkRepr::Evaluated(Value::Thunk(ref inner_thunk)) => { let inner_repr = inner_thunk.0.borrow().clone(); drop(thunk); self.0.replace(inner_repr); } /* ... */ } This code path created a copy of the inner `ThunkRepr` of a nested thunk, and moved that copy into the `ThunkRepr` of the parent. The effect of this was that the original `ThunkRepr` (unforced!) lived on in the original thunk, without the memoization of the subsequent forcing applying to it. This had the result that Tvix would repeatedly evaluate these thunks without ever memoizing them, if they occured repeatedly as shared inner thunks. Most notably, this would *always* occur when builtins.import was used. What's the solution? ==================== I have completely rewritten `Thunk::force_trampoline_self` to make all flows that can occur in it explicit. I have also removed the outer loop inside of that function, and resorted to more use of trampolining instead. The function is now well-commented and it should be possible to read it from top-to-bottom and get a general sense of what is going on, though the trampolining itself (which is implemented in the VM) needs to be at least partially understood for this. What's the new problem(s)? ========================== One new (known) problem is that we have to construct `Error` instances in all error types here, but we do not have spans available in some thunk-related situations. Due to b/238 we cannot ask the VM for an arbitrary span from the callsite leading to the force. This means that there are now code paths where, under certain conditions, causing an evaluation error during thunk forcing will panic. To fix this we will need to investigate and fix b/238, and/or add a span tracking mechanism to thunks themselves. What other impacts does this have? ================================== With this commit, eval of nixpkgs mostly succeeds (things like stdenv evaluate to the same hashes for us and C++ Nix, meaning we now construct identical derivations without eval breaking). Due to this we progress much further into nixpkgs, which lets us uncover more additional bugs. For example, after this commit we can quickly see that cl/7949 introduces some kind of behavioural issue and should not be merged as-is (this was not apparent before). Additionally, tvix-eval is now seemingly very fast. When doing performance analysis of a nixpkgs eval, we now mostly see the code path for shelling out to C++ Nix to add things to the store in there. We still need those code paths, so we can not (yet) do a performance analysis beyond that. Change-Id: I738525bad8bc5ede5d8c737f023b14b8f4160612 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8012 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-23 r/5747 chore(tvix/eval): delete "useless parenthesis" warning/optimisationVincent Ambo1-26/+0
Two main reasons: 1. Traversing the structure to do this optimisation is actually *slower* than not optimising it. 2. There are literally hundreds of thousands of incidences of this in nixpkgs, and with some of the weird code there some of these (functionally) useless parens are actually required for readability reasons. Change-Id: I1044b1c5f9fe20df4b6085851fc3b191277c65dc Reviewed-on: https://cl.tvl.fyi/c/depot/+/7917 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-22 r/5735 feat(tvix/eval): support builtins implemented in Nix itselfVincent Ambo1-16/+76
This makes it possible to inject builtins into the builtin set that are written in Nix code, and which at runtime are represented by a thunk that will compile them the first time they are used. Change-Id: Ia632367328f66fb2f26cb64ae464f8f3dc9c6d30 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7891 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-22 r/5734 docs(tvix/eval): update some outdated commentsVincent Ambo1-8/+3
These don't apply anymore since the "antidote-CL". Change-Id: I40ee73ef43d44bbfc650a8fe6c2b33263dd06959 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7890 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-21 r/5721 refactor(tvix/eval): administer antidote for poisonAdam Joseph4-121/+45
The codebase contains a lot of complexity and odd roundabout handling for shadowing globals. I'm pretty sure none of this is necessary, and all of it disappears if you simply make the globals part of the ordinary identifier resolution chain, with their own scope up above the root scope. Then the ordinary shadowing routines do the right thing, and no special cases or new terminology are required. This commit does that. Note by tazjin: This commit was originally abandoned when Adam decided not to take away reviewer bandwidth for this at the time (eval was still in a much earlier stage). As we've recently done some significant refactoring of globals initialisation this came up again, and it seems we can easily cover the use-cases of the poison tracking in other ways now, so I've rebased, updated and resurrected the CL. Co-Authored-By: Vincent Ambo <tazjin@tvl.su> Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: Ib3309a47a7b31fa5bf10466bade0d876b76ae462 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7089 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-20 r/5706 feat(tvix/eval): add error contexts to annotate error kindsVincent Ambo1-7/+9
This makes it possible for users to add additional context to an error, which will then be rendered as an additional secondary span in the formatted error output. We should strive to do this basically anywhere errors are raised that can occur multiple times, *especially* during type casts. This was triggered by me debugging a type cast error attached to a fairly large-ish span (a builtin invocation). Change-Id: I51be41fabee00cf04de973935daf34fe6424e76f Reviewed-on: https://cl.tvl.fyi/c/depot/+/7849 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-17 r/5675 refactor(tvix/eval): remove `Box` in new_suspended_nativeVincent Ambo1-2/+2
This is unnecessary, Rc already provides all the boxing we need. Change-Id: I08cf0939c48da43f04c847526c7e5dae5336d528 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7749 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2023-01-17 r/5674 feat(tvix/eval): add builtins to builtinsVincent Ambo1-2/+32
This is a somewhat terrifying hack that enables us to support `builtins.builtins`, by running a "fake compilation" inside of a suspended native thunk that can resolve the weak pointer to the globals. With this implementation, the thunk at `builtins.builtins` actually resolves to the "real" `builtins` (verified with a new test). This is kind of ugly, and it's something users shouldn't use, but bubbling a warning out of this is difficult at the moment due to a little bit of trickery with how the spans in suspended native thunks work (they don't) (see b/237, b/238) Change-Id: I67d0e93246dd5b279c960aeda00402031aa12af3 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7748 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-06 r/5607 feat(tvix/eval): skip & warn for useless parenthesisVincent Ambo1-0/+26
Change-Id: I567ca0682012b9d09f1217e57a104ac5671f8d82 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7771 Tested-by: BuildkiteCI Reviewed-by: raitobezarius <tvl@lahfa.xyz> Reviewed-by: flokli <flokli@flokli.de>
2023-01-06 r/5606 feat(tvix/eval): warn on empty let-bindingsVincent Ambo1-0/+3
Change-Id: Ib6ef7ce514abbd3e372dfe9df7137aa36dbda9d4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7770 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-06 r/5605 refactor(tvix/eval): short-circuit on empty attrs in compilerVincent Ambo1-0/+9
This is marginally more efficient and has simpler bytecode. Change-Id: Iad37c9aeef24583e8f696911bcd83d43639f2e36 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7769 Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-06 r/5604 feat(tvix/eval): warn about empty `inherit`sVincent Ambo1-0/+5
Change-Id: I82bec6fe2210bcb88c46fd2fdf3e26bd613d1c1f Reviewed-on: https://cl.tvl.fyi/c/depot/+/7768 Reviewed-by: flokli <flokli@flokli.de> Reviewed-by: raitobezarius <tvl@lahfa.xyz> Tested-by: BuildkiteCI
2023-01-06 r/5603 fix(tvix/eval): compile but don't emit dead codeVincent Ambo2-9/+33
This adds a mechanism to the compiler to compile an expression without emitting any code. This allows for detected dead code to still be compiled to detect errors & warnings inside of it. Change-Id: Ie78479173570e9c819d8f32ae683ce34234a4c5d Reviewed-on: https://cl.tvl.fyi/c/depot/+/7767 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-06 r/5602 feat(tvix/eval): implement initial compiler::optimiser moduleVincent Ambo2-0/+130
This optimiser can rewrite some expressions into more efficient forms, and warn users about those cases. As a proof-of-concept, only some simple boolean comparisons are supported for now. Change-Id: I7df561118cfbad281fc99523e859bc66e7a1adcb Reviewed-on: https://cl.tvl.fyi/c/depot/+/7766 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-06 r/5601 refactor(tvix/eval): take owned ast::Expr in Compiler::compileVincent Ambo2-34/+34
This adds a very minimal amount of additional Rc-increments (~1 per compilation), but makes it a lot easier to add an AST-optimising compiler pass without incurring a lot of extra cost. Change-Id: I57208bdfc8882e3ae21c5850e14aa380d3ccea36 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7765 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-06 r/5599 feat(tvix/eval): add Evaluation::compile_only methodVincent Ambo1-1/+3
This would make it possible to implement something like a linter based on the tvix-eval compiler warnings. Change-Id: I1feb4e7c4a44be7d1204b0a962ab522fd32b93c6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7763 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2023-01-06 r/5598 fix(tvix/eval): don't increase `with_stack_size` in scope inheritsVincent Ambo1-1/+1
There was probably a misunderstanding somewhere about the with_stack_size being related to how far away it is from the with, but it is about whether there is a with at all. This broke a warning (`UselessInherit`), and may actually have let to more inefficient codegen in some cases. Change-Id: I08338ea59ae39dad01ca8a4e09d934a936cdea2f Reviewed-on: https://cl.tvl.fyi/c/depot/+/7762 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
2023-01-04 r/5581 refactor(tvix/eval): streamline construction of globals/builtinsVincent Ambo2-21/+187
Previously the construction of globals (a compiler-only concept) and builtins (a (now) user-facing API) was intermingled between multiple different modules, and kind of difficult to understand. The complexity of this had grown in large part due to the implementation of `builtins.import`, which required the notorious "knot-tying" trick using Rc::new_cyclic (see cl/7097) for constructing the set of globals. As part of the new `Evaluation` API users should have the ability to bring their own builtins, and control explicitly whether or not impure builtins are available (regardless of whether they're compiled in or not). To streamline the construction and allow the new API features to work, this commit restructures things by making these changes: 1. The `tvix_eval::builtins` module is now only responsible for exporting sets of builtins. It no longer has any knowledge of whether or not certain sets (e.g. only pure, or pure+impure) are enabled, and it has no control over which builtins are globally available (this is now handled in the compiler). 2. The compiler module is now responsible for both constructing the final attribute set of builtins from the set of builtins supplied by a user, as well as for populating its globals (that is identifiers which are available at the top-level scope). 3. The `Evaluation` API now carries a `builtins` field which is populated with the pure builtins by default, and can be extended by users. 4. The `import` feature has been moved into the compiler, as a special case. In general, builtins no longer have the ability to reference the "fix point" of the globals set. This should not change any functionality, and in fact preserves minor differences between Tvix/Nix that we already had (such as `builtins.builtins` not existing). Change-Id: Icdf5dd50eb81eb9260d89269d6e08b1e67811a2c Reviewed-on: https://cl.tvl.fyi/c/depot/+/7738 Reviewed-by: sterni <sternenseemann@systemli.org> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
2022-12-25 r/5486 fix(tvix/eval): fix current clippy warningsVincent Ambo2-5/+4
It's been a while since the last time, so quite a lot of stuff has accumulated here. Change-Id: I0762827c197b30a917ff470fd8ae8f220f6ba247 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7597 Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-12-21 r/5457 refactor(tvix/eval): add a LightSpan type for lighter span trackingVincent Ambo1-1/+2
This type carries the information required for calculating a span (i.e. the chunk and offset), instead of the span itself. The span is then only calculated in cases where it is required (when throwing errors). This reduces the eval time for `builtins.length (builtins.attrNames (import <nixpkgs> {}))` by *one third*! The data structure in chunks that carries span information reduces in-memory size by trading off the speed of retrieving span information. This is because the span information is only actually required when throwing errors (or emitting warnings). However, somewhere along the way we grew a dependency on carrying span information in thunks (for correctly reporting error chains). Hitting the code paths for span retrieval was expensive, and carrying the spans in a different way would still be less cache-efficient. This change is the best tradeoff I could come up with. Refs: b/229. Change-Id: I27d4c4b5c5f9be90ac47f2db61941e123a78a77b Reviewed-on: https://cl.tvl.fyi/c/depot/+/7558 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-12-21 r/5454 refactor(tvix/eval): add name-based index over compiler's localsVincent Ambo2-34/+108
Instead of finding locals by doing 2x O(n) walks over the compiler's locals list, use a secondary name-based index for resolving locals by name. Previously, almost 60% (!!) of eval time on some expressions over nixpkgs was spent in `Local::has_name`. This function doesn't even exist anymore now, and eval speed about doubles as a result. Note that this doesn't exactly make the locals code easier to read, but I'm also not sure what we can simplify in there in general. This fixes b/227. Change-Id: I29ce5eb9452b02d3b358c673e1f5cf8082e2fef9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7560 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-12-21 r/5452 feat(tvix/eval): wrap Closure in Rc<> to match cppnix semanticsAdam Joseph1-1/+1
Change-Id: I595087eff943d38a9fc78a83d37e207bb2ab79bc Reviewed-on: https://cl.tvl.fyi/c/depot/+/7443 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-11-05 r/5251 fix(tvix/eval): Scope.inherit(): fix scope_depth, with_stack_depthAdam Joseph1-0/+2
Scope_depth and with_stack_depth were being reset to zero for nested function abstractions. Fortunately nothing depends on them being computed correctly in these cases, but it sure was confusing. Change-Id: I59980b6a5aff043f60079f97211220b0086eb97d Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7091 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-11-05 r/5250 refactor(tvix/eval): rename Opcode::DataLocalIdx to DataStackIdxAdam Joseph1-1/+1
It is very confusing that this opcode is called DataLocalIdx, but it carries a StackIdx rather than a LocalIdx. It seems like this really ought to be called DataStackIdx, but maybe I've misunderstood; if so please explain it to me. Change-Id: I91f6ffa759412beef0b91d3c19ec0d873fe51b99 Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7088 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-11-04 r/5237 fix(tvix/eval): inline mis-named Local::above()Adam Joseph1-6/+1
If self.depth > other.depth then self is deeper than other, so self is *below* other, not above it. Let's just inline the function. Change-Id: I8dda3d90cbc86c8a6fa01bc4a5e506a2e403bd20 Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7090 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-27 r/5214 refactor(tvix/eval): search-and-replace changesAdam Joseph1-5/+5
This commit contains two search-and-replace renames which are broken out from I04131501029772f30e28da8281d864427685097f in order to reduce the noise in that CL: - `is_thunk -> is_suspended_thunk`, since there are now OpThunkClosure and OpThunkSuspended - `compile_lambda_or_thunk` -> `compile_lambda_or_suspension` Change-Id: I7cc5bbb75ef6605e3428c7be27e812f41a10c127 Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7037 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-27 r/5213 feat(tvix/eval): builtins.import without RefCellAdam Joseph1-45/+51
CL/6867 added support for builtins.import, which required a cyclic reference import->globals->builtins->import. This was implemented using a RefCell, which makes it possible to mutate the builtins during evaluation. The commit message for CL/6867 expressed a desire to eliminate this possibility: This opens up a potentially dangerous footgun in which we could mutate the builtins at runtime leading to different compiler invocations seeing different builtins, so it'd be nice to have some kind of "finalised" status for them or some such, but I'm not sure how to represent that atm. This CL replaces the RefCell with Rc::new_cyclic(), making the globals/builtins immutable once again. At VM runtime (once opcodes start executing) everything is the same as before this CL, except that the Rc<RefCell<>> introduced by CL/6867 is turned into an rc::Weak<>. The function passed to Rc::new_cyclic works very similarly to overlays in nixpkgs: a function takes its own result as an argument. However instead of laziness "breaking the cycle", Rust's Rc::new_cyclic() instead uses an rc::Weak. This is done to prevent memory leaks rather than divergence. This CL also resolves the following TODO from CL/6867: // TODO: encapsulate this import weirdness in builtins The main disadvantage of this CL is the fact that the VM now must ensure that it holds a strong reference to the globals while a program is executing; failure to do so will cause a panic when the weak reference in the builtins is upgrade()d. In theory it should be possible to create strong reference cycles the same way Rc::new_cyclic() creates weak cycles, but these cycles would cause a permanent memory leak -- without either an rc::Weak or RefCell there is no way to break the cycle. At some point we will have to implement some form of cycle collection; whatever library we choose for that purpose is likely to provide an "immutable strong reference cycle" primitive similar to Rc::new_cyclic(), and we should be able to simply drop it in. Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: I34bb5821628eb97e426bdb880b02e2097402adb7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7097 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-26 r/5201 docs(tvix/eval): StackIdx, LocalIdx UpvalueIdxAdam Joseph1-3/+1
This adds a comment noting that StackIdx is an offset relative to the base of the current CallFrame, whereas UpvalueIdx is an absolute index into the upvalues array. It also removes the confusing mention of StackIdx in the descriptive comment for LocalIdx. They index into totally different structures; one exists at runtime and the other exists at compile time. Change-Id: Ib932b1b0679734c15001e8c5c95a08293fa016b4 Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7017 Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-23 r/5186 feat(tvix/eval): initial attempt at setting lambda namesVincent Ambo2-2/+18
When compiling a lambda, take the name of the outer slot (if available) and store it as the name on the lambda. These names are then shown in the observer, and nowhere else (so far). It is of course common for these things to thread through many different context levels (e.g. `f = a: b: c: ...`), in this setup only the outermost closure or thunk gains the name, but it's better than nothing. Change-Id: I681ba74e624f2b9e7a147144a27acf364fe6ccc7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7065 Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-23 r/5184 fix(tvix/eval): thunk let-expressionVincent Ambo1-1/+5
There are some rare scope cases with deferred access where this doesn't behave correctly otherwise. Change-Id: I6c774f5e62c1cb50b598026c54727017a52cd22d Reviewed-on: https://cl.tvl.fyi/c/depot/+/7064 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-10-23 r/5183 fix(tvix/eval): fix condition for useless inherit warningVincent Ambo1-2/+2
The warning needs to consider whether it is occuring inside of a thunk, i.e. the dynamic ancestry chain of lambda contexts must be inspected and not just the current scope. Change-Id: I5cf5482d67a8bbb9f03b0ecee7a62f58754f8e59 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7063 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-10-23 r/5182 refactor(tvix/eval): simplify check for deferring upvalue resolutionVincent Ambo1-9/+4
This check is now actually simply equivalent to checking whether the target has been initialised or not. Change-Id: I30660d11073ba313358f3a64234a90ed81abf74c Reviewed-on: https://cl.tvl.fyi/c/depot/+/7062 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-23 r/5180 refactor(tvix/eval): simplify self-reference checkVincent Ambo1-1/+1
Checking the computed depth and stack slot against the computed depth and stack slot is equivalent to just checking the indices into the locals vector against each other (i.e. "is the slot we're compiling into the slot we're accessing?") Change-Id: Ie85a68df073e3b2e3d9aba7fe8634c48eada81fc Reviewed-on: https://cl.tvl.fyi/c/depot/+/7059 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-21 r/5172 fix(tvix): distinguish search- and relative path resolution errorssterni1-2/+2
Failures to resolve a nix search path lookup in angle brackets can be caught using tryEval (if it reaches the runtime). Resolving relative paths (either to the current directory or the current user's home) can never be caught, even if they happen inside a thunk at runtime (which is currently the case for home-relative paths). Change-Id: I7f73221df66d82a381dd4063358906257826995a Reviewed-on: https://cl.tvl.fyi/c/depot/+/7025 Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-19 r/5159 feat(tvix/eval): deduplicate overlap between Closure and ThunkAdam Joseph2-4/+36
This commit deduplicates the Thunk-like functionality from Closure and unifies it with Thunk. Specifically, we now have one and only one way of breaking reference cycles in the Value-graph: Thunk. No other variant contains a RefCell. This should make it easier to reason about the behavior of the VM. InnerClosure and UpvaluesCarrier are no longer necessary. This refactoring allowed an improvement in code generation: `Rc<RefCell<>>`s are now created only for closures which do not have self-references or deferred upvalues, instead of for all closures. OpClosure has been split into two separate opcodes: - OpClosure creates non-recursive closures with no deferred upvalues. The VM will not create an `Rc<RefCell<>>` when executing this instruction. - OpThunkClosure is used for closures with self-references or deferred upvalues. The VM will create a Thunk when executing this opcode, but the Thunk will start out already in the `ThunkRepr::Evaluated` state, rather than in the `ThunkRepr::Suspeneded` state. To avoid confusion, OpThunk has been renamed OpThunkSuspended. Thanks to @sterni for suggesting that all this could be done without adding an additional variant to ThunkRepr. This does however mean that there will be mutating accesses to `ThunkRepr::Evaluated`, which was not previously the case. The field `is_finalised:bool` has been added to `Closure` to ensure that these mutating accesses are performed only on finalised Closures. Both the check and the field are present only if `#[cfg(debug_assertions)]`. Change-Id: I04131501029772f30e28da8281d864427685097f Signed-off-by: Adam Joseph <adam@westernsemico.com> Reviewed-on: https://cl.tvl.fyi/c/depot/+/7019 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-18 r/5156 fix(tvix/eval): wrap dynamic resolution in an extra thunkVincent Ambo1-2/+9
Without this change it was possible to cause situations (see the new test) in which a `with`-namespace was forced prematurely. Change-Id: I879ea7763b43edc693feace2c73c890d426fafd3 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7031 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: Adam Joseph <adam@westernsemico.com>
2022-10-17 r/5154 feat(tvix/eval): Validate closed formalsGriffin Smith1-7/+6
Validate "closed formals" (formal parameters without an ellipsis) via a new ValidateClosedFormals op, which checks the arguments (in an attr set at the top of the stack) against the formal parameters on the Lambda in the current frame, and returns a new UnexpectedArgument error (including the span of the formals themselves!!) if any arguments aren't allowed Change-Id: Idcc47a59167a83be1832a6229f137d84e426c56c Reviewed-on: https://cl.tvl.fyi/c/depot/+/7002 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-17 r/5153 feat(tvix/eval): Record formals on lambdaGriffin Smith1-11/+20
In preparation for both implementing the `functionArgs` builtin and adding support for validating closed formals, record information about the formal arguments to a function *on the Lambda itself*. This may seem a little odd for the purposes of just closed formal checking, but is something we have to have anyway for builtins.functionArgs so I figured I'd do it this way to kill both birds with one stone. Change-Id: Ie3770a607bf352a1eb395c79ca29bb25d5978cd8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7001 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-16 r/5150 refactor(tvix/eval): unify compile_lambda() with thunk()Adam Joseph1-61/+59
This resolves a TODO. Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: If4d2124648ac88094e547e1ad7f1b446feb26182 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7010 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-16 r/5147 fix(tvix/eval): resolve home relative paths at runtimesterni1-12/+8
Home relative paths depend on the environment to be resolved. We have elected to do everything that depends on the environment, e.g. resolving SPATH expressions using NIX_PATH, at runtime, so tvix evaluation would continue to behave correctly even if we separated the compilation and execution phases more, e.g. via serializing bytecode. Then the value of HOME, NIX_PATH etc. could reasonably change in the time until execution, yielding wrong results if the resolution results were cached in the bytecode. We also take the opportunity to fix the broken path concatenation previously found in the compiler, fixing b/205. Another thing we could consider is emitting a warning for home relative path literals, as they are by nature relatively fragile. One sideeffect of this change is that home path resolution errors become catchable which is not the case in C++ Nix. This will need to be fixed up in a subsequent change. Change-Id: I30bd69b575667c49170a9fdea23a020565d0f9ec Reviewed-on: https://cl.tvl.fyi/c/depot/+/7024 Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI
2022-10-16 r/5146 refactor(tvix/eval): make OpFindFile use internal UnresolvedPathsterni1-1/+1
To assert that OpFindFile is only emitted for specially compiled SPATH expressions, as well as make sure it doesn't accidentally operate on “ordinary values”, introduce an UnresolvedPath internal value. If OpFindFile sees a non-UnresolvedPath value, it'll crash. Note that this change is not done purely for OpFindFile: We may want to compile SPATH expressions as function calls to __findFile (like C++ Nix does) in the future, so the UnresolvedPath value would definitely need to be an ordinary string again then. Rather, this change is done in preparation for resolving home dir relative paths at runtime (since they depend on the environment) for which we'll need a similar mechanism to OpFindFile. Change-Id: I6acf287f35197cd9e13377079f972b9d36e5b22e Reviewed-on: https://cl.tvl.fyi/c/depot/+/7023 Autosubmit: sterni <sternenseemann@systemli.org> Reviewed-by: Adam Joseph <adam@westernsemico.com> Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
2022-10-13 r/5121 fix(tvix/eval): fix Compiler::new on wasmVincent Ambo1-1/+3
This path normalisation business causes runtime panics on WebAssembly because those operations are unsupported. Maybe this shouldn't be happening in the compiler anyways, not sure, but for now this commit adds a workaround based on the target to disable the normalisation if we're compiling for wasm. Change-Id: I908a84fbdffc3401f8d443e2c73ec673e9f397ff Reviewed-on: https://cl.tvl.fyi/c/depot/+/7004 Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-10-13 r/5120 fix(tvix/eval): src/compiler: ensure root_dir is absoluteAdam Joseph1-8/+16
Cppnix immediately absolutizes pathnames at parse time; if you write `./foo`, it is immediately converted to `$(pwd)/foo` and manipulated as an absolute path at all times. To avoid having to introduce filesystem access operations in the implementation of otherwise-pure builtins, let's guarantee that the `root_dir` of the VM is always an absolute path. Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: I7cbbae2cba4b2716ff3f5ff7c9ce0ad529358c8a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6995 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-10-13 r/5119 refactor(tvix/eval): factor out all calls to canon_pathAdam Joseph1-2/+1
Right now we're pretending that the Rust library path_clean does the same thing that cppnix's canonPath() does. This is not true. It's close enough for the test suite, but may come back to bite us. Let's create our own canon_path() function and call that in all the places where we intend to match the behavior of cppnix's canonPath(). That way when we fix this we can fix it once, in one place. Signed-off-by: Adam Joseph <adam@westernsemico.com> Change-Id: Ia6f9577f62f49ef352ff9cfa5efdf37c32d31b11 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6993 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-10-10 r/5097 fix(tvix/eval): Actually trace spans for thunksGriffin Smith1-1/+1
Currently, the span on *all* thunk force errors is the span at which the thunk is forced, which for recursive thunk forcing ends up just being the same span over and over again. This changes the span on thunk force errors to be the span at which point the thunk is *created*, which is a bit more helpful (though the printing atm is a little... crowded). To make this work, we have to thread through the span at which a thunk is created into a field on the thunk itself. Change-Id: I81474810a763046e2eb3a8f07acf7d8ec708824a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6932 Autosubmit: grfn <grfn@gws.fyi> Reviewed-by: Adam Joseph <adam@westernsemico.com> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-10 r/5090 fix(tvix/eval): Thunk `if` exprGriffin Smith1-1/+3
Since the body of an `if` expr can refer to deferred upvalues, it needs to be thunked so when we actually compile those deferred upvalues we have something for the finalize op to point at. Without this all sorts of weird things can happen due to the finalize op being run in the wrong lambda context, up to and including a panic. Change-Id: I040d5e1a7232fd841cfa4953539898fa49cbbb83 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6929 Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: tazjin <tazjin@tvl.su> Autosubmit: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-10-10 r/5087 feat(tvix/eval): Initial resolution of `<...>` pathsGriffin Smith1-6/+17
This commit implements (lazy) resolution of `<...>` paths via either the NIX_PATH environment variable, or the -I command-line flag - both handled via EvalOptions. As a result, EvalOptions can no longer derive Copy, meaning we have to clone it at each line of the repl - this is probably not a huge deal as repl performance is not exactly an inner loop and we're not cloning very much. Internally, this works by creating a thunk which pushes a constant containing the string inside the brackets to the stack, then a new opcode to resolve that path via the `NixPath`. To get that opcode to work, we now have to pass in the NixPath when constructing the VM. This (intentionally) leaves out proper implementation of path resolution via `findFile` (cppnix just calls whatever identifier called findFile is in scope!!!) as that's widely considered a bit of a misfeature, but if we do decide to implement that down the road it likely wouldn't be more than a few extra ops within the thunk introduced here. Change-Id: Ibc979b7e425b65cbe88599940520239a4a10cee2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6918 Autosubmit: grfn <grfn@gws.fyi> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
2022-10-10 r/5082 refactor(tvix/eval): Compile OpAssert using conditional jumpsGriffin Smith1-4/+22
In order to behave nicely with tryEval, asserts need to leave the instruction pointer in a reasonable place even if they fail - whereas with the previous implementation catching a failed assert would still end up running the op for the *body* of the assert. With this change, we compile asserts much more like an `if` expression with conditional jumps rather than having an OpAssert op. Change-Id: I1b266c3be90185c84000da6b1995ac3e6fd5471b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6925 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI