about summary refs log tree commit diff
path: root/tvix/eval/src/vm.rs
AgeCommit message (Collapse)AuthorFilesLines
2022-09-06 r/4674 feat(tvix/eval): Add Compiler::thunk method for emitting thunksVincent Ambo1-0/+2
The logic in this method is *very* similar to `compile_lambda`. It is intended to be called around any expression that should be thunked (such as function applications, attribute set values, etc.). Change-Id: Idfbb2daa9f4b735095378fb9c39a2fd07c8cff91 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6344 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4667 feat(tvix/eval): implement OpFinalise instructionVincent Ambo1-0/+13
This instruction finalises the initialisation of deferred upvalues in closures (and soon, thunks). The compiler does not yet emit this instruction, some more accounting is needed for that. Change-Id: Ic4181b26e19779e206f51e17388559400da5f93a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6337 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4666 feat(tvix/eval): set up deferred upvalues at runtimeVincent Ambo1-2/+2
This will leave a sentinel value in the upvalue slot in which the actual value is to be captured after resolution once a scope is fully set up. Change-Id: I12b37b0dc8d32603b03e675c3bd039468e70b354 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6336 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4665 feat(tvix/eval): detect deferred upvalue capturingVincent Ambo1-0/+5
Uses the threaded through slot offset to determine whether initialisation of a captured local upvalue must be defered to a later point where all values of a scope are available. This adds a new data representation to the opcode for this situation, but the equivalent runtime handling is not yet implemented. This is in part because there is more compiler machinery needed to find the resolution point. Change-Id: Ifd0c393f76abfe6e2d91483faf0f58947ab1dedc Reviewed-on: https://cl.tvl.fyi/c/depot/+/6329 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-06 r/4660 fix(tvix/eval): correct runtime error for missing dynamic upvalueVincent Ambo1-0/+6
Change-Id: I75c351619780fdc5186a54f3df9b244ada984069 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6324 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4659 fix(tvix/eval): instantiate *new* closures from blueprints each timeVincent Ambo1-9/+13
The previous closure refactoring introduced a bug in which the same closure object would get mutated constantly for each instance of a closure, which is incorrect behaviour. This commit instead introduces an explicit new Value variant for the internal "blueprint" that the compiler generates (essentially just the lambda) and uses this variant to construct the closure at runtime. If the blueprint ever leaks out to a user somehow that is a critical bug and tvix-eval will panic. As a ~treat~ test for this, the fibonacci function is being used as it is a self-recursive closure (i.e. different instantiations of the same "blueprint") getting called with different values and it's good to have it around. Change-Id: I485de675e9bb0c599ed7d5dc0f001eb34ab4c15f Reviewed-on: https://cl.tvl.fyi/c/depot/+/6323 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4658 fix(tvix/eval): correctly thread through dynamic upvaluesVincent Ambo1-7/+64
This puts together the puzzle pieces for threading dynamic upvalues (that is, upvalues resolved from the `with`-stack) all the way through. Reading the test case enclosed in this commit and walking through it is recommended to understand what problem is being tackled here. In short, because the compiler can not statically know *which* with-scope a dynamic argument is resolved from it needs to lay the groundwork for resolving from *all* possible scopes. There are multiple different approaches to doing this. The approach chosen in this commit is that if a dynamic upvalue is detected, the compiler will emit instructions to close over this dynamic value in *all* enclosing lambda contexts. It uses a new instruction for this that will leave around a sentinel value in case an identifier could not be resolved, and wire the location of this found value (or sentinel) up through the upvalues to the next level of nesting. In this tradeoff, tvix potentially closes over more upvalues than are needed (but in practice, how often do people create *really* deep `with`-stacks? and in *this* kind of code situation? maybe we should even warn for this!) but avoids keeping the entire attribute sets themselves around. Looking at the test case, each surrounding closure will close over *all* dynamic identifiers that are referenced later on visible to it, but only the last one for each identifier will actually end up being used. This also covers our bases for an additional edge-case this creates, in which an identifier potentially resolves to a dynamic upvalue *and* to a dynamic value within the function's own scope (again, would anyone really do this?) by introducing a resolution instruction for that particular case. There is likely some potential for cleaning up this code which is quite ugly in some parts, but as this implementation is now carefully calibrated to work I decided it is time to commit it and clean it up in subsequent commits. Change-Id: Ib701e3e6da39bd2c95938d1384036ff4f9fb3749 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6322 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4654 fix(tvix/eval): account for stack offset when pushing a `with` scopeVincent Ambo1-1/+4
Change-Id: I4b98eaea3ed5059c29938a117a9d59499a0bb95d Reviewed-on: https://cl.tvl.fyi/c/depot/+/6318 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4653 feat(tvix/eval): implement capture of self-recursive upvaluesVincent Ambo1-3/+9
With this change, it becomes possible for functions to call themselves as they are being defined in local bindings. Change-Id: Ib46a39ba17b1452b5673d96fa729d633d237241a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6314 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-06 r/4651 refactor(tvix/eval): encapsulate internal mutability within ClosureVincent Ambo1-16/+16
This is required to efficiently construct the upvalue array at runtime, as there are situations where during Closure construction multiple things already have a reference to the closure (e.g. a self-reference). Change-Id: I35263b845fdc695dc873de489f5168d39b370f6a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6312 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-04 r/4635 feat(tvix/eval): implement upvalue resolution in `with` scopesVincent Ambo1-1/+6
These need to be handled specially by the runtime if the compiler determines that a given local must be resolved via `with`. Note that this implementation has a bug: It currently allows `with` inside of nested lambdas to shadow statically known identifiers. This will be cleaned up in the next commit. Change-Id: If196b99cbd1a0f2dbb4a40a0e88cdb09a009c6b9 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6299 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-04 r/4634 fix(tvix/eval): ensure OpResolveWith can be tracedVincent Ambo1-16/+16
The previous implementation of OpResolveWith manually controlled the loop iteration, which skipped over the disassembler's tracing instruction. Instead, the resolution of dynamic variables has been delegated to a new helper function. This has the additional benefit that the loop labels are no longer required, making things a bit cleaner. Change-Id: If22b74c3d49c74bf3a1ec4497cb761a9ee6cf2a4 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6298 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4629 feat(tvix/eval): implement runtime closure construction (OpClosure)Vincent Ambo1-1/+28
Implements the final bit of logic remaining for wiring up closures, which is the runtime construction of closure objects. When encountering an OpClosure, the VM walks through the bytecode collecting all the upvalue location operands (see commit introducing the OpCode::Data* variants for details) and stores the runtime values in the new closures upvalue vector. After that, the handling of the closure itself becomes functionally identical to that of lambdas. With this initial implementation of closures there are several large optimisation potentials available, the two most notable ones are: - Distinguish the runtime representation of lambdas and closures explicitly. - Detect and handle multiple-arity functions directly in the compiler. However, for both of these we should wait until we have appropriate benchmarking infrastructure in place. This is because our test implementations have shown that the complexity of either of these changes is quite significant, and we do not yet know if they really pay off. Change-Id: I077e977810fd5cb2b1ecd7f1a119e728025dd786 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6295 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4628 feat(tvix/eval): implement OpGetUpvalue in the VMVincent Ambo1-4/+6
This resolves an upvalue at runtime by pushing it on the stack from the closure's upvalue vector. Change-Id: Ic3e7a7ecd9f7032f679114a1995e5bbf83062fcf Reviewed-on: https://cl.tvl.fyi/c/depot/+/6294 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4627 refactor(tvix/eval): store Closure inside of the VM's call framesVincent Ambo1-6/+6
In preparation for implementing calling of closures, store a closure directly in the VMs call frame. Change-Id: Iad24cd8c49fee4ebd4d0c84ffaa4c2505ee3dfd6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6293 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4625 feat(tvix/eval): compile creation of closure objectsVincent Ambo1-1/+8
Fully implements the instructions for compiling closure objects (without runtime handling yet). Closure (and thunk) objects are created at runtime by capturing all known upvalues. To represent this, the instructions for creating them need to have a variable number of arguments. Due to that, this commit introduces new variants in OpCode that are not actually operations, but data. If the VM is implemented correctly, the instruction pointer should never point at these. Due to this, the VM will panic if it sees a data operand during an execution run. Change-Id: Ic56b49b3a42736dc437751e76df0e89c8d0619c6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6291 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4623 feat(tvix/eval): implement compilation of upvalue accessVincent Ambo1-0/+2
This adds a new upvalue tracking structure in the compiler to resolve upvalues and track their positions within a function when compiling a closure. The compiler will emit runtime upvalue access instructions after this commit, but the creation of the runtime closure object etc. is not yet wired up. Change-Id: Ib0c2c25f686bfd45f797c528753068858e3a770d Reviewed-on: https://cl.tvl.fyi/c/depot/+/6289 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-03 r/4622 refactor(tvix/eval): add opcode::Count type for less ambiguityVincent Ambo1-6/+6
Change-Id: Ibde0b2baa1128a74c1364ee9a6330b62db3da699 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6288 Autosubmit: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4621 refactor(tvix/eval): add opcode::StackIdx type for less ambiguityVincent Ambo1-3/+3
Change-Id: I9b9de1f681972c205d4d20bc5731d2ce79858edb Reviewed-on: https://cl.tvl.fyi/c/depot/+/6287 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4619 refactor(tvix/eval): add opcode::JumpOffset type for less ambiguityVincent Ambo1-5/+5
This adds a transparent wrapper around `usize` used for jump offsets in the opcodes. This is a step towards getting rid of ambiguous plain `usize` usage in the opcode. Change-Id: I21e35e67d94b32d68251908b96c7f62b6f56a8bb Reviewed-on: https://cl.tvl.fyi/c/depot/+/6282 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4616 refactor(tvix/eval): avoid cloning in NixAttrs::update if possibleVincent Ambo1-3/+9
Refactors the update function to take the attribute sets by value instead. To facilitate this, we use an equivalent of the currently unstable `Rc::clone_or_unwrap` in the VM when encountering attribute sets, so that in cases where the only references to the attrs being updated are the ones on the stack those clones are avoided completely. This does make update() a little bit more tricky internally, as some optimised branches can directly return the moved value, and others need to destructure with ownership. For this reason there are now two different match statements handling the different ownership cases. Change-Id: Ia77d3ba5c86afb75b9f1f51758bda61729ba5aab Reviewed-on: https://cl.tvl.fyi/c/depot/+/6279 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-03 r/4613 refactor(tvix/eval): rename Value::NotFound & OpAttrOrNotFoundVincent Ambo1-4/+4
grfn suggested clearer naming for these in cl/6166. Change-Id: I83164bf1d1902ebd42272e9d5d63819a0f6a72c5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6277 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-03 r/4605 refactor(tvix/eval): introduce Closure struct in Value typeVincent Ambo1-2/+2
This struct will carry the upvalue machinery in addition to the lambda itself. For now, all lambdas are wrapped in closures (though technically analysis of the environment can later remove innermost Closure wrapper, but this optimisation may not be worth it). Change-Id: If2b68549ec1ea4ab838fdc47a2181c694ac937f2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6269 Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-02 r/4597 refactor(tvix/eval): add NixAttrs::contains functionVincent Ambo1-1/+1
This avoids copying around the value more than needed. Change-Id: I35949d16dad7fb8f76e0f641eaccf48322144777 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6263 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
2022-09-02 r/4585 feat(tvix/eval): add initial representation of builtinsVincent Ambo1-0/+5
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>
2022-09-02 r/4583 feat(tvix/eval): implement opcode for function calls in VMVincent Ambo1-8/+24
Nix functions always have a single argument and we do not yet make efforts to optimise this in Tvix for known multi-argument functions being directly applied. For this reason, the call instruction is fairly simple and just calls out to construct a new call frame. Note that the logic for terminating the run loop has moved to the top of the dispatch; this is because the loop run needs to be skipped if the call frame for the current lambda has just been dropped. Change-Id: I259bc07e19c1e55cd0a65207fa8105b23052b967 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6249 Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi> Tested-by: BuildkiteCI
2022-09-02 r/4582 refactor(tvix/eval): add VM::call helper to set up call framesVincent Ambo1-7/+12
Change-Id: Ia7ff572af90ae379b23bbd0f5215cd13a4dc0ab5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6248 Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-01 r/4578 refactor(tvix/eval): use call frame for top-level lambdaVincent Ambo1-14/+29
This wires up most of the machinery for executing different call frames inside of the VM and stuffs the top-level lambda which the compiler outputs in there, as well. Change-Id: Ib6201b3e3be1af96a4d195f6eb147f452860ffc3 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6242 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4577 feat(tvix/eval): add call frame struct to VMVincent Ambo1-0/+8
This is going to carry the data for a function invocation inside of the VM. Change-Id: I86664563a7e35697a64294acd37ffde037fbd32d Reviewed-on: https://cl.tvl.fyi/c/depot/+/6241 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4576 refactor(tvix/eval): return a lambda from the compilerVincent Ambo1-3/+3
Changes the internal compiler plumbing to not just return a chunk of code, but the same chunk wrapped inside of a lambda value. This is one more step towards compiling runtime lambdas. Change-Id: If0035f8e65a2970c5ae123fc068a2396e1d8fd72 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6240 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4571 feat(tvix/eval): carry optional SyntaxNode in error typeVincent Ambo1-13/+16
This starts paving the way for nicer, source-code based error reporting. Right now the code paths in the VM do not emit annotated errors, as we do not yet preserve that structure from the compiler. However, error emitting code paths in the compiler have been amended to include known nodes. Change-Id: I1b74410ffd891c40cd913361bd73c4336ec8aa5b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6235 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi>
2022-09-01 r/4567 refactor(tvix/eval): Upgrade to latest rnix-parserVincent Ambo1-1/+1
Since the latest published version of rnix-parser on crates.io, the crate has undergone major changes which are only available in the git repository at the moment. This commit updates the compiler to this newer version of rnix. Most notably, the entire AST provided by rnix is now wrapped in the AST type system. As a result of this traversal is much nicer in many places, especially for things like nested attribute selection. There are a handful of smaller features missing for full feature parity with the previous version, especially handling of path literals, but PRs for these already exist in rnix-parser. Change-Id: Icde6d393067976549492b7d89c4cc49e5e575fc7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6231 Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-09-01 r/4566 feat(tvix/eval): implement `assert` operatorVincent Ambo1-0/+6
This implements `assert`, which evaluates an expression and aborts evaluation if the value is not `true`. At this point we should introduce eval-failed-* tests; probably asserting against some representation of the error enum? Change-Id: If54c8f616d89b829c1860a4835dde60a2cd70d7a Reviewed-on: https://cl.tvl.fyi/c/depot/+/6230 Reviewed-by: grfn <grfn@gws.fyi> Reviewed-by: sterni <sternenseemann@systemli.org> Tested-by: BuildkiteCI
2022-08-31 r/4556 feat(tvix/eval): Implement OpResolveWith instructionVincent Ambo1-1/+20
Change-Id: I4d2a69f28a6b6199b3ff48ef81135e7da9fe1c3b Reviewed-on: https://cl.tvl.fyi/c/depot/+/6222 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-31 r/4553 feat(tvix/eval): implement OpPopWithVincent Ambo1-0/+3
Change-Id: I752d9428a73f893741746e9d5b79e8d8d570bb81 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6219 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
2022-08-31 r/4552 feat(tvix/eval): implement with_stack in VMVincent Ambo1-1/+6
Change-Id: I805c24c9a751ded15725ba9be651aa0869e013e5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6218 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org> Reviewed-by: grfn <grfn@gws.fyi>
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>