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2022-08-31 r/4551 feat(tvix/eval): compile `with` expressionVincent Ambo1-0/+2
Adds an additional structure to the compiler's scope to track the runtime "with stack", i.e. the stack of values through which identifiers should be dynamically resolved within a with-scope. When encountering a `with` expression, the value from which the bindings should be resolved is pushed onto the stack and tracked by the compiler in the "with stack", as well as with a "phantom value" which indicates that the stack contains an additional slot which is not available to users via identifiers. Runtime handling of this is not yet implemented. Change-Id: I5e96fb55b6378e8e2a59c20c8518caa6df83da1c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6217 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-30 r/4543 fix(tvix/eval): `or` should handle non-attrset values, tooVincent Ambo1-5/+9
If a nested attrpath encounters a non-set value, the sentinel value denoting a lack of next values should be emitted. This mirrors the behaviour of Nix. Change-Id: Ia80443d5a11243cc6d98dcab1249a3f5fdf77e27 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6210 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4542 fix(tvix/eval): allow use of ? operator on non-set typesVincent Ambo1-3/+9
Nix allows this, but always returns false. Tvix needs to do the same. Change-Id: Ic9eec90834a0d0969eea5316d5c25032d3691d94 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6209 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-30 r/4537 fix(tvix/eval): address various clippy lintsVincent Ambo1-12/+12
Change-Id: I3ea0f51475e80948adfeb5d1620c1f2665cc39bc Reviewed-on: https://cl.tvl.fyi/c/depot/+/6201 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-30 r/4533 feat(tvix/eval): implement optional runtime tracingVincent Ambo1-1/+13
This adds a `disassembler` feature to the crate configuration that traces the operations executed and the state of the stack at runtime. This can be enabled by compiling with `--feature disassembler`. This will also gain a more sensible layout of code slices eventually. Change-Id: I34c15e1cd346ecc4362b5afba6bf82dd49359d20 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6193 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-28 r/4524 feat(tvix/eval): add local identifier accessVincent Ambo1-0/+5
This makes basic `let ... in ...` statements work correctly. It does not yet account for the call frames pushed into the VM during function application. Change-Id: I67155171daf1a43011b96716dd9d1ab04b27db33 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6190 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-28 r/4522 feat(tvix/eval): compile simple `let ... in ...` expressionsVincent Ambo1-0/+14
These expressions now leave the binding values on the stack, and clean up the scope after the body of the expression. While variable access is not yet implemented (as the identifier node remains unhandled), this already gives us the correct stack behaviour. Change-Id: I138c20ace9c64502c94b2c0f99a6077cd912c00d Reviewed-on: https://cl.tvl.fyi/c/depot/+/6188 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4499 feat(tvix/vm): add opcodes for new Value::NotFound sentinelVincent Ambo1-0/+17
This sentinel value is going to be used for certain nested accesses into attribute sets. There is a new instruction similar to `OpAttrsSelect` which leaves the sentinel on the stack if a key is not found, instead of raising an error. Additionally, a new jump instruction makes its jump operation conditional on finding such a sentinel value. Change-Id: I2642f0a0bcc85bbe0ead68ea09a7dd794dbedeac Reviewed-on: https://cl.tvl.fyi/c/depot/+/6166 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-26 r/4495 feat(tvix/eval): implement `?` operator (single-level only)Vincent Ambo1-0/+7
This makes it possible to check things like `{} ? a` with a single level of nesting. Change-Id: I567c36fcfd2f9e2f60071acd3ebfe56dea59b26f Reviewed-on: https://cl.tvl.fyi/c/depot/+/6161 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-26 r/4492 feat(tvix/eval): implement attribute set access operatorVincent Ambo1-0/+15
Fairly straightforward, handling the optimised representations manually and otherwise delegating to BTreeMap. Note that parsing of raw identifiers is not yet implemented. Encountering an identifier node usually means that there is locals access going on, so we need a special case for compiling a node in such a way that an identifier's literal value ends up on the stack. Change-Id: I13fbab7ac657b17ef3f4c5859fe737c321890c8a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6158 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-26 r/4491 fix(tvix/eval): add operation to assert boolean typeVincent Ambo1-0/+14
This operation is required because both sides of the logical operators are strictly evaluated by Nix, even if the resulting value is not used further. For example, in our implementation of `&&`, if the left-hand side is `true`, then the result of the expression is simply the right-hand side value. This value must be asserted to be a boolean for the semantics of the language to work correctly. Change-Id: I34f5364f2a444753fa1d8b0a1a2b2d9cdf7c6700 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6157 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-25 r/4486 feat(tvix/compiler): implement `||` operatorVincent Ambo1-0/+6
Same dance as `&&` but logically inverted. Change-Id: I213e200e3836527e9abe510f354ee7cd1f70d041 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6151 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4483 feat(tvix/eval): implement if/else expressionsVincent Ambo1-0/+18
These expressions use simple jumps to skip the correct expression conditionally in the bytecode by advancing the instruction pointer. Note that these expressions are already covered by a test behind the `nix_tests` feature flag, but adding more is probably sensible. Change-Id: Ibe0eba95d216321c883d3b6b5816e2ab6fe7eef1 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6148 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4480 refactor(tvix/eval): encapsulate list construction in value::listVincent Ambo1-16/+5
Ensuring that the implementation is not leaking out of the module lets us keep things open for optimisations (e.g. empty list or pairs through tuples). Change-Id: I18fd9b7740f28c55736471e16c6b4095a05dd6d0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6145 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4479 feat(tvix/eval): implement list concatenationVincent Ambo1-0/+7
Change-Id: Icdf715d116371a9f139bdf95266410bf967bef25 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6144 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-25 r/4478 feat(tvix/eval): implement binary comparison operatorsVincent Ambo1-7/+36
This is accomplished by simply delegating to the Rust implementations of (Partial)Ord and (Partial)Eq, which are implemented for Value and underlying wrapper types to behave like they do in Nix. To ease the implementation overhead, a new comparison operator macro has been added to the VM module. Incomparable types will raise a new error variant when a comparison is attempted, containing both supplied types. This mimics the information carried in the error thrown by C++ Nix. Change-Id: Ia19634d69119d40722f3ca672387bc3a80096998 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6143 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-25 r/4477 refactor(tvix/vm): simplify implementation of OpEqualVincent Ambo1-8/+1
This can now fully delegate to PartialEq of Value Change-Id: Iaa9f4ec9b8830d516d72f83a93ab2df9a6e5697c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6142 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4475 feat(tvix/eval): implement attrset update (`//`) operatorVincent Ambo1-0/+9
The underlying implementation does a few tricks based on which pair of attrset representations is encountered. Particularly the effect of short-circuiting the empty cases might be relevant in nixpkgs/NixOS, due to the use of lib.optionalAttrs. Change-Id: I22b978b1c69af12926489a71087c6a6219c012f3 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6140 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-25 r/4472 feat(tvix/eval): implement string concatenationVincent Ambo1-1/+13
Change-Id: If61066e59232b2bad42b5cb5f0f2d9b9c416be8b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6137 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-25 r/4471 refactor(tvix/vm): use a macro to handle binary arithmetic operatorsVincent Ambo1-49/+32
Instead of constructing another runtime value representing the pair on which to perform arithmetic, implement the same logic in the shape of a macro. This is designed to be compatible with operators like `+` that work both as an arithmetic operator AND as an operator on another pair of types. Change-Id: I1c83649ead6117f811f1fb45482d0cadf811125e Reviewed-on: https://cl.tvl.fyi/c/depot/+/6136 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-08-24 r/4457 feat(tvix/value): introduce string representation with &'static strVincent Ambo1-3/+3
For cases where the strings are statically known (such as the oft-occuring name/value), this can be a useful optimisation. It's also much more convenient in tests. Change-Id: Ie462b684805bd4986ea5e85ca4bff663bc2d3c3c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6111 Tested-by: BuildkiteCI Reviewed-by: eta <tvl@eta.st>
2022-08-24 r/4454 refactor(tvix/value): encapsulate attrset logic within value::attrsVincent Ambo1-189/+3
The internal optimisations of the set representation were previously leaking into the VM, which is highly undesirable. Keeping it encapsulated allows us to do additional optimisations within value::attrs without being concerned about its use in the VM. Change-Id: I7e7020bb0983b9d355d3db747b049b2faa60131f Reviewed-on: https://cl.tvl.fyi/c/depot/+/6108 Reviewed-by: eta <tvl@eta.st> Tested-by: BuildkiteCI
2022-08-14 r/4443 refactor(tvix/rm): introduce helper for AttrSet Entry APIVincent Ambo1-20/+27
There are multiple points where an insertion needs to be done into an attribute set, but copying the key or checking for presence before insertion should be avoided As that is a little bit noisy, it's been factored out into a helper function in this commit. Change-Id: Ibcb054ebeb25a1236c06c812f47c8e74180d4fc9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6107 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-14 r/4442 feat(tvix/vm): implement first nested attribute set constructionVincent Ambo1-39/+130
This can construct non-overlapping nested attribute sets (i.e. `{ a.b = 1; b.c = 2; }`, but not `{ a.b = 1; a.c = 2; }`). In order to do the latter, it's necessary to gain the ability to manipulate the in-progress attribute set construction. There's multiple different options for this ... Change-Id: If1a762a720b175e8eb4216cbf96a7434d22640fb Reviewed-on: https://cl.tvl.fyi/c/depot/+/6106 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-13 r/4440 fix(tvix/eval): Fail on duplicate attribute set keysVincent Ambo1-1/+5
Change-Id: I57373ca76d0e25a5d08a8dfce9d5949099326fc0 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6104 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-13 r/4439 feat(tvix/eval): construct internal attribute path representationVincent Ambo1-0/+18
This is required for constructing nested attribute sets at runtime. There'll be quite a lot of optimisation potential with this solution eventually, if it should turn out to be a bottleneck. This introduces a conceptual change, in that the `Value` enum is now an enum representing "all runtime values" instead of "all Nix language types". This makes sense in general, as this type will also contain Chunk representations etc. which are not exposed to users. Change-Id: Ic5f72b2a0965b146c6a451efad34c6a81ca1aad8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6103 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-13 r/4438 feat(tvix/vm): implement construction of optimised KV attrsetsVincent Ambo1-0/+77
For name/value pairs (which occur extremely often in Nix and make up a significant chunk of the runtime cost of evaluating nixpkgs) we substitute an optimised representation. For now this will only be used if the name/value pair keys were specified as literal identifiers or strings (i.e. if chunks are encountered as keys they are not forced and a normal attribute set backed by a map will be constructed). Change-Id: Ic79746c323e627528bd58b1a6024ee8d0aff7858 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6102 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-08-13 r/4434 feat(tvix): implement string interpolationVincent Ambo1-0/+15
This adds a new instruction which assembles an interpolated string from a specified number of fragments, which are already going to be located on the stack in the right position. This will raise a type error if any of the fragments do not evaluate to a string. Change-Id: I5756248fa3e9fcc3d063c14db40b332f7e20a588 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6098 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-13 r/4430 feat(tvix/vm): implement list constructionVincent Ambo1-1/+17
Change-Id: Iec2b4910800ab29daae6d71b58a8acd14ccb1cc1 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6094 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su>
2022-08-13 r/4427 feat(tvix/eval): implement trivial attribute set literalsVincent Ambo1-1/+18
Implements attribute set literals without nesting. Technically this already supports dynamic key fragments (evaluating to strings), though the only way to create these (interpolation) is not yet implemented. However, creating simple attribute sets like `{ }`, or `{ a = 15; }` or `{ a = 10 * 2; }` works. Recursive attribute sets are not yet implemented as we do not have any kind of scope access yet anyways. This is implemented using a new instruction that creates an attribute set with a given number of elements by popping key/value pairs off the stack. Change-Id: I0f9aac7a131a112d3f66b131297686b38aaeddf2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6091 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-13 r/4423 feat(tvix/eval): add Value variants for strings & attrsetsVincent Ambo1-2/+2
Change-Id: Idebf663ab7fde3955aae50f635320f7eb6c353e8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6087 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4417 refactor(tvix/eval): move NumberPair struct definition to vm moduleVincent Ambo1-1/+7
This isn't relevant to the value type itself. Change-Id: I678bc92a8a530b1081ed498bf3ff7925217bcc01 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6081 Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4416 feat(tvix/compiler): incompletely handle true/false/null literalsVincent Ambo1-3/+3
These are a bit tricky to implement because Nix technically treats them as identifiers, and only if the identifier is not explicitly overridden within the scope does it yield the expected literal values. Note that weirdness even occurs with scopedImport. Change-Id: Ie55723405ccfcc25da37c5a08fa3332f37cf9ae5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6080 Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4415 feat(tvix/eval): implement boolean inversion operatorVincent Ambo1-1/+5
Change-Id: Icb1d449fdee4d67b5f1eefdbc01baa1584ea0a67 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6079 Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4414 feat(tvix/eval): implement equality operatorVincent Ambo1-4/+18
Change-Id: I9dd54aed72cd7e67593dc76f5a046ebbda40c26f Reviewed-on: https://cl.tvl.fyi/c/depot/+/6078 Tested-by: BuildkiteCI Autosubmit: tazjin <tazjin@tvl.su> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4411 feat(tvix/eval): implement unary negation operatorVincent Ambo1-0/+12
Change-Id: I5d012cc073e55d79d7b34b88283aab3164864293 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6075 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4410 feat(tvix/eval): implement simple arithmetic binary operationsVincent Ambo1-1/+50
Implements simple arithmetic operations (+, -, *, /). There is some scaffolding included to pop and coerce pairs of numbers, as the Nix language will let arithmetic operators apply to arbitrary pairs of number types (always resulting in floats if the types are mixed). Change-Id: I5f62c363bdea8baa6ef812cc64c5406759d257cf Reviewed-on: https://cl.tvl.fyi/c/depot/+/6074 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-08-12 r/4407 feat(tvix/eval): add initial stack-based VMVincent Ambo1-0/+55
This can't do anything other than compute a single literal, for now Change-Id: Ia28f9da51c906b590a198e77a4ca5d45a871106b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6071 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>