Commit graph

853 commits

Author SHA1 Message Date
sterni
0005737f11 fix(tvix/eval): make tvix display values like nix-instantiate(1)
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
2023-06-15 11:01:06 +00:00
sterni
80a71abb48 test(tvix/eval): move division by zero tests into tvix_tests
These were added by us in r/5276, so they should go into our test suite.

Change-Id: I6dc74fc242f33c22a17e0b4aee546ccae886ac85
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8774
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
2023-06-14 16:22:07 +00:00
sterni
1125b6b7b7 test(tvix/eval): add test case for builtins set pointer equality
Unsupported by Tvix at the moment. Documents b/280.

Change-Id: I48844feeefa9da8ed7e5d85300d52bb5650f82d2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8772
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
2023-06-14 16:01:19 +00:00
sterni
d5b989ddc0 test(tvix/eval): re-enable blackhole test
Change-Id: Id933f3bd708aa3342b9fd6a5584e65ee11751ff8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8773
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: sterni <sternenseemann@systemli.org>
2023-06-14 15:59:45 +00:00
sterni
8e5551329a fix(tvix/eval): don't thunk home relative paths
C++ Nix resolves home relative paths at [parse] time. This is not an
option for us, since it prevents being able to separate the compilation
and execution phase later (e.g. precompiled nix expressions). However, a
practical consequence of this is that paths expressions are always
literals (strict) and never thunks.

[parse]: 7066d21a0d/src/libexpr/parser.y (L518-L527)

Change-Id: Ie4b9dc68f62c86d6c7fd5f1c9460c850d97ed1ca
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7041
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-06-14 10:57:28 +00:00
sterni
5139cc45c2 test(tvix/eval): builtins.substring's behavior with negative args
Change-Id: Ie8b97d174e9d58e33bf08c9b9e0afeeddd089ba8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8700
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-06-12 09:38:08 +00:00
Linus Heckemann
5733274876 fix(tvix/eval): allow negative substring lengths
Nix uses string::substr without checking the sign of the length[1].
The NixOS testing infrastructure relies on this[2], and on the
implicit conversion of that to the maximum possible value for a
size_t.

[1]: ecae62020b/src/libexpr/primops.cc (L3597)
[2]: c7c2984716/nixos/lib/testing/driver.nix (L29)

Change-Id: I6d0caf6830b6bda3fdf44c40c81de6a1befeca7b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8746
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-06-12 08:38:49 +00:00
Linus Heckemann
2b4ad47c16 fix(tvix/eval): emit only warnings on shadowed outputs
Unfortunately, nixpkgs has at least one case[1] where the out environment
variable is shadowed -- though it doesn't cause a problem, since it's
shadowed with the correct value, odd as this may be!

[1]: c7c2984716/pkgs/development/python-modules/pybind11/default.nix (L19)

Change-Id: Ibf6790d2484dc9cce8e424feeb5886664d498dc3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8696
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2023-06-11 20:59:34 +00:00
sterni
a2303da01f fix(tvix/eval): use normal thunking behavior for default in formals
When comparing to C++ Nix, we notice that the thunking of default
expressions in function formals corresponds to their normal thunking,
e.g. literals are not thunked. This means that we can just invoke
compile() without much of a care and trust that it will sort it out
correctly.

If function formals blow up as a result of this, it likely indicates
that the expression is treated incorrectly by compile(), not
compile_param_pattern().

Change-Id: I64acbff2f251423eb72ce43e56a0603379305e1d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8704
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-06-07 15:19:21 +00:00
sterni
10c6cb7251 fix(tvix/eval): type check function argument with set pattern
C++ Nix forces and typechecks the passed argument even if it is not
necessary in order to compute the return value of the function. I
discovered this when I thought our formals miscompilation might be that
we are too strict, but doesn't look like it in this case.

Change-Id: Ifb3c92592293052c489d1e3ae8c7c54e4b6b4dc6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8701
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
2023-06-07 15:17:20 +00:00
sterni
617130b088 refactor(tvix/eval): don't track idx twice in compile_param_pattern
Change-Id: I27f9105ddb20d84342550b2a73b479a7764ee3fe
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8699
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
2023-06-07 15:17:19 +00:00
sterni
d09f333d0e fix(tvix/eval): thunk lambda expressions
As cl/8658 and b/274 reveal, lambda expressions are also wrapped in
thunks.

Resolves b/274.

Change-Id: I02fe5c8730ac76748d940e4f4427116587875275
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8662
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-29 19:36:41 +00:00
sterni
2aab01ac29 fix(tvix/eval): thunk HasAttr expressions
HasAttrs was weird because with longer attribute paths it would
sometimes not turn out to be a thunk. If it was a thunk, it'd usually
still do some eval strictly which we'll want to avoid.

Verified against C++ Nix using a new test suite introduced in a later
CL.

Change-Id: I6d047ccc68d046bb268462f170a3c4f3c5ddeffe
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8656
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-29 12:44:09 +00:00
sterni
9d0425acc0 fix(tvix/eval): thunk legacy let to match regular one
Probably no real world code broken by this overzealous evaluation, but
let's be thorough!

Change-Id: Ib405a677182eab7940ace940c68e107573473a54
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8655
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
2023-05-29 12:44:08 +00:00
sterni
385c797884 fix(tvix/eval): thunk unary operator applications
Unary operator applications are thunked which can easily be observed by

  nix-instantiate --eval -E '[ (!true) (-1) ]'

Unfortunately, there are few simple expressions where this makes a
difference in the end result. Thus it only cropped up when using nixpkgs
for cross compilation: Here we would compile the expression

  !(stdenv.cc.isGNU or false)

to assemble python3Minimal's passthru attribute set (at least this seems
to be the most likely explanation from the backtraces I've studied).
This means that an unthunked

    <stdenv.cc.isGNU or false>
    OpForce
    OpInvert

would be performed in order to assemble this attribute set, causing
stdenv.cc to be evaluated too early, causing an infinite recursion.

Resolves b/273.

It seems that having a test suite that doesn't use --strict and relies
on thunks rendered as <CODE> would be beneficial for catching such
issues. I've not been able to find a test case with --strict that
demonstrates the problem fixed in this CL.

Change-Id: I640a5827b963f5b9d0f86fa2142e75e3a6bbee78
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8654
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-29 12:44:08 +00:00
sterni
3b33c19a9c fix(tvix): don't call function eagerly in genList, map & mapAttrs
mapAttrs, map and genList call Nix functions provided by the caller and
store the result of applying them in a Nix data structure that does not
force all of its contents when forced itself. This means that when such
a builtin application is forced, the Nix function calls performed by the
builtin should not be forced: They may be forced later, but it is also
possible that they will never be forced, e.g. in

    builtins.length (builtins.map (builtins.add 2) [ 1 2 3 ])

it is not necessary to compute a single application of builtins.add.

Since request_call_with immediately performs the function call
requested, Tvix would compute function applications unnecessarily before
this change. Because this was not followed by a request_force, the
impact of this was relatively low in Nix code (most functions return a
new thunk after being applied), but it was enough to cause a lot of
bogus builtins.trace applications when evaluating anything from
`lib.modules`. The newly added test includes many cases where Tvix
previously incorrectly applied a builtin, breaking a working expression.

To fix this we add a new helper to construct a Thunk performing a
function application at runtime from a function and argument given as
`Value`s. This mimics the compiler's compile_apply(), but does itself
not require a compiler, since the necessary Lambda can be constructed
independently.

I also looked into other builtins that call a Nix function to verify
that they don't exhibit such a problem:

- Many builtins immediately use the resulting value in a way that makes
  it necessary to compute all the function calls they do as soon as
  the outer builtin application is forced:

  * all
  * any
  * filter
  * groupBy
  * partition

- concatMap needs to (shallowly) force the returned list for
  concatenation.

- foldl' is strict in the application of `op` (I added a comment that
  makes this explicit).

- genericClosure needs to (shallowly) force the resulting list and some
  keys of the attribute sets inside.

Resolves b/272.

Change-Id: I1fa53f744bcffc035da84c1f97ed25d146830446
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8651
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-26 22:35:39 +00:00
Vincent Ambo
22776280b5 feat(tvix/eval): unthunk empty lists and attribute sets
Change-Id: Ie66cb1b163a544d45d113fd0f866286f230b0188
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7960
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
2023-05-25 11:28:13 +00:00
Vincent Ambo
5d3fb33baa feat(tvix/eval): implement unthunking in compiler
This feature allows the compiler to detect situations where the
created thunk is useless and can be merged into the parent chunk
instead.

The only case where the compiler does this initially is when
statically optimising a select expression.

For example, previously the expression `builtins.length` compiled into
two thunks:

1. An "inner" thunk which contained an `OpConstant` that had the
   optimised `length` builtin in it.

2. An "outer" thunk which contained an `OpConstant` to access the
   inner thunk, and the trailing OpForce of the top-level program.

With this change, the inner thunk is skipped completely and the outer
chunk directly contains the `length` builtin access.

This can be applied in several situations, some easier than others,
and we will add them in as we go along.

Change-Id: Ie44521445fce1199f99b5b17712833faea9bc357
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7959
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
2023-05-25 11:28:13 +00:00
Vincent Ambo
3aea9bf527 feat(tvix/eval): implement Chunk::extend method
This method extends the contents of one chunk with that of another,
effectively merging the thunks together.

This will be used for the upcoming "unthunking" functionality.

Change-Id: I6ad74232cd7f3eca198ed921e455205e00d76e6b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7958
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-05-25 11:28:13 +00:00
Florian Klink
d25962b9a4 refactor(tvix/eval): stop borrowing &mut self
This does undo cl/8571.

Change-Id: Ib14b4e7404f906e346304b6113860ae811afc94a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8631
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
2023-05-25 11:11:59 +00:00
Florian Klink
11771a06ae refactor(tvix/eval): use &Path instead of PathBuf
This allows getting rid of some clones in eval/src/vm/generators.rs.

Change-Id: I330390307d3bcfeef19c98954c753ee55b1ccee3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8604
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-22 09:43:33 +00:00
Florian Klink
b4bb9062ea fix(tvix/eval): add path where useful to ErrorKind::IO
These two places didn't add the path from the context to the
ErrorKind, but simply relied on the
impl From<std::io::Error> for tvix_eval::ErrorKind, which doesn't add
the path.

Change-Id: Ifc7dbbe305d24242b0705de1dea34e8923e9d2cb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8603
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
2023-05-22 09:43:21 +00:00
Florian Klink
b7ab6c0856 refactor(tvix/eval/io): use io::Error instead of tvix_eval errors
We didn't return anything useful other than ErrorKind::IO anyways.

We can use io::ErrorKind::Unsupported for DummyIO.

Fixes b/271.

Change-Id: Icb231e9b38168e8b6fa473bfa405d160357b317f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8602
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-22 09:42:58 +00:00
Florian Klink
8bd7ced1fb feat(tvix/eval/io): allow &mut self in EvalIO
It's okay if these calls mutate some internal state inside an
implementation.

Change-Id: I12bb11bde0310778c3da1275696bf7de058863a3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8571
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
2023-05-14 18:59:55 +00:00
Vincent Ambo
969fbcd6d4 fix(tvix/eval): builtins.trace prints to stderr
Change-Id: Icf577396035474d6977e627058aba5805c61985e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8563
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
2023-05-12 12:50:59 +00:00
Vincent Ambo
ce502bdc89 refactor(tvix/eval): improve representation of chunk/span mapping
This switches out the previous compressed representation (count of
instructions per span) with a representation where the chunk's span
list stores the index of the first operation that belongs to a span,
and finds the right span by using a binary search when looking them
up.

This improves the lookup complexity from O(n) to O(log n).

This improvement was suggested and (mostly) implemented by GPT-4. I
only fixed up some names and updated the logic for deleting
spans (which it only did not do because I didn't tell it about that).

The code was verified by producing a complex error before/after the
change and ensuring that all spans in the error match exactly.

Co-Authored-By: GPT-4
Change-Id: Ibfa12cc6973af1c9b0ae55bb464d1975209771f5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8385
Reviewed-by: ezemtsov <eugene.zemtsov@gmail.com>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
2023-03-31 16:46:19 +00:00
Vincent Ambo
2d305fd5b3 refactor(tvix/eval): retain call frames when entering calls
This grows the frame stack as the call stack grows, which yields *much*
better user-facing error messages.

I haven't measured the performance impact this has yet, for now I'm
still just trying to add more information to errors and then cut down
again where necessary.

Change-Id: I89f058ef31979edacf4667775d460b60704ce4d7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8334
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
2023-03-27 09:02:43 +00:00
Vincent Ambo
ba138712e4 feat(tvix/eval): add Evaluation::strict to toggle top-level deepseq
This makes it possible for callers to control whether they can receive
partially evaluated values from an evaluation or not.

We're actually flipping the default behaviour to non-strict top-level
evaluation, which means that callers have to set `strict = true` on
the Evaluation to get the previous behaviour.

Change-Id: Ic048e9ba09c88866d4c3177d5fa07db11c4eb20e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8325
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
2023-03-22 13:44:20 +00:00
Vincent Ambo
a5f28eea94 fix(tvix/eval): print unevaluated thunks like Nix does
Change-Id: Ie4c563e933f571f45cb4f4efe650d1b65f119e8d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8324
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: tazjin <tazjin@tvl.su>
2023-03-22 13:44:19 +00:00
Vincent Ambo
80aaadfc19 fix(tvix/eval): use span of set for OpForce in attribute access
Emits the span of the `set` that is being accessed in the `force`
operation of an attribute access.

Looking at traces, it's a lot more useful to get information about
*what* is being forced, as in cases like `foo.bar` it can be
misleading to have an error highlight `bar`, when the error occured
while forcing `foo` to be able to access `bar` in the first place.

Change-Id: Id46ff28f20c67cb4971727ac52cc4811795cea2d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8272
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2023-03-17 19:40:40 +00:00
Vincent Ambo
8c13f18d11 feat(tvix/eval): report all known spans on infinite recursion
This reports the span

1. of the code within a thunk,
2. of the place where the thunk was instantiated,
3. of the place where the thunk was first forced,
4. of the place where the thunk was forced again,

when yielding an infinite recursion error, which hopefully makes it
easier to debug them.

The spans are tracked in the ThunkRepr::Blackhole variant when putting
a thunk under evaluation.

Note that we currently have some loss of span precision in the VM loop
when switching between frame types, so spans 3/4 are currently a bit
wonky. Working on it.

Change-Id: Icbd2a9df903d00e8c2545b3fc46dcd2a9e3e3e55
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8270
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
2023-03-17 19:32:38 +00:00
Vincent Ambo
3fa6b13c1e feat(tvix/eval): track span of first force in a thunk blackhole
This is step 1 towards being able to use all 4 spans that we know when
dealing with infinite recursion. It tracks the span at which the
force of a thunk was first requested when constructing a blackhole, so
that we can highlight the spans of the first and second forces.

These are actually the least relevant spans, but the easiest to put in
place, more coming soon.

Change-Id: I4c7e82f6211b98756439d4148a4191457cc46807
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8269
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
2023-03-17 19:31:37 +00:00
Vincent Ambo
5095e4f269 feat(tvix/eval): add generator "name" to NativeError kind
This produces traces in which we can see what kind of native code was
run. Note that these "names" are named after the generator message, so
these aren't *really* intended for end-user consumption, but we can
give them saner names later.

Example:
https://gist.github.com/tazjin/82b24e92ace8e821008954867ee05057

This already makes the traces a little easier to parse.

Change-Id: Idcd601baf84f492211b732ea0f04b377112e10d0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8268
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
2023-03-17 19:31:37 +00:00
Vincent Ambo
ea80e0d3f8 feat(tvix/eval): enrich errors with VM's frame stack information
When emitting an error at runtime, the VM will now use the new
`NativeError` and `BytecodeError` error kinds (which just wrap inner
errors) to create a set of diagnostics to emit.

The primary diagnostic is emitted last, with `error` type (so it will
be coloured red in terminals), the other ones will be emitted with
`note` type, highlighting the causal chain.

Example:
https://gist.github.com/tazjin/25feba7d211702453c9ebd5f8fd378e4

This is currently quite verbose, and we can cut down on this further,
but the purpose of this commit is to surface more information first of
all before worrying about the exact display.

Change-Id: I058104a178c37031c0db6b4b3e4f4170cf76087d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8266
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-03-17 19:31:37 +00:00
Vincent Ambo
b78ae941a4 fix(tvix/eval): use coerce_to_string in builtins.substring
This actually uses coercion under the hood in C++ Nix. See the test
for an example.

Change-Id: Id56b364acf269225b6829d0b600e0222f8b3608d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8322
Reviewed-by: andi <andi@notmuch.email>
Tested-by: BuildkiteCI
2023-03-17 19:17:29 +00:00
Vincent Ambo
b5f5a1595d chore(tvix/eval): remove some dead code
This was commented out and forgotten during the generator refactor, oh
well.

Change-Id: I474b685159a955a846db462da0dd0067af177b04
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8321
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-03-17 11:01:07 +00:00
Vincent Ambo
d456705352 chore(tvix): Generator{Request|Response} -> VM{Request|Response}
We settled on this being the most reasonable name for this construct.

Change-Id: Ic31c45461a842f22aa05f4446123fe3a61dfdbc0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8291
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-14 09:22:22 +00:00
Adam Joseph
1e80b9ea8b chore(tvix/eval): mark async functions which are called by the VM
Given Rust's current lack of support for tail calls, we cannot avoid
using `async` for builtins.  This is the only way to avoid
overflowing the cpu stack when we have arbitrarily deep
builtin/interpreted/builtin/interpreted/... "sandwiches"

There are only five `async fn` functions which are not builtins
(some come in multiple "flavors"):

- add_values
- resolve_with
- force, final_deep_force
- nix_eq, nix_cmp_eq
- coerce_to_string

These can be written iteratively rather than recursively (and in
fact nix_eq used to be written that way!).  I volunteer to rewrite
them.  If written iteratively they would no longer need to be
`async`.

There are two motivations for limiting our reliance on `async` to
only the situation (builtins) where we have no other choice:

1. Performance.

   We don't really have any good measurement of the performance hit
   that the Box<dyn Future>s impose on us.  Right now all of our
   large (nixpkgs-eval) tests are swamped by the cost of other
   things (e.g. fork()ing `nix-store`) so we can't really measure
   it.  Builtins tend to be expensive operations anyways
   (regexp-matching, sorting, etc) that are likely to already cost
   more than the `async` overhead.

2. Preserving the ability to switch to `musttail` calls.

   Clang/LLVM recently got `musttail` (mandatory-elimination tail
   calls).  Rust has refused to add this mainly because WASM doesn't
   support, but WASM `tail_call` has been implemented and was
   recently moved to phase 4 (standardization).  It is very likely
   that Rust will get tail calls sometime in the next year; if it
   does, we won't need async anymore.  In the meantime, I'd like to
   avoid adding any further reliance on `async` in places where it
   wouldn't be straightforward to replace it with a tail call.

https://reviews.llvm.org/D99517

https://github.com/WebAssembly/proposals/pull/157

https: //github.com/rust-lang/rfcs/issues/2691#issuecomment-1462152908
Change-Id: Id15945d5a92bf52c16d93456e3437f91d93bdc57
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8290
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
2023-03-13 21:33:58 +00:00
Adam Joseph
e7a534e0c6 refactor(tvix/eval): reduce fetch{forced|captured}_with visibility
This commit moves fetch_forced_with and fetch_captured_with into the
scope of their only caller (resolve_with).

Change-Id: I9a8bc27228888729d591e8cb021c431b2b6468f5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8289
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
2023-03-13 21:33:58 +00:00
Adam Joseph
47895c4c30 feat(tvix/eval): rewrite nix_cmp_ordering to be nonrecursive
This rewrites nix_cmp_ordering as an iterative loop, which
eliminates the extra pinned-boxing helper function.

Change-Id: I33d0ecc913e02affd8fd4c7bc1c9ecfdf4c7deb9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8288
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
2023-03-13 21:22:12 +00:00
Vincent Ambo
b3f8d66a6a chore(tvix/eval): prune some dependencies & features
* We no longer need backtrace-on-stack-overflow, as we no longer
  overflow the stack with the recent eval refactorings. This was weird
  voodoo anyways, introduced earlier to debug some cases where stack
  overflows occured.

* default features of genawaiter crate are not needed, as we don't use
  their proc macros

Change-Id: I346fc5a18d7f117ee805909a8be8f535b96be76c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8263
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 20:30:59 +00:00
Vincent Ambo
94513525b9 refactor(tvix/eval): reorder bytecode operations match by frequency
This reorders the operations in the VM's main `match` statement while
evaluating bytecode according to the frequency with which these
operations appear in some nixpkgs evaluations.

I used raw data that looks like this:
https://gist.github.com/tazjin/63d0788a78eb8575b04defaad4ef610d

This has a small but noticeable impact on evaluation performance.

No operations have changed in any way, this is purely moving code
around.

Change-Id: Iaa4ef4f0577e98144e8905fec88149c41e8c315c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8262
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00
Vincent Ambo
e48a17a6b3 docs(tvix/eval): fix reference to Empty message in a comment
Change-Id: I3dc30cca33fbbd8e8686655635ee471f5937d9f8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8257
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 20:30:59 +00:00
Vincent Ambo
cc59cbf3e2 refactor(tvix/eval): rename VM::tail_call_value -> VM::call_value
The name of this was not accurate anymore after all the recent
shuffling, as noted by amjoseph. Conceptual tail calls here only occur
for Nix bytecode calling Nix bytecode, but things like a builtin call
actually push a new native frame.

Change-Id: I1dea8c9663daf86482b8c7b5a23133254b5ca321
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8256
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 20:30:59 +00:00
Vincent Ambo
5d9bfd7735 fix(tvix/eval): emit warnings from builtins.import again
Wires up generator logic to emit warnings that already have spans
attached again.

Change-Id: I9f878cec3b9d4f6f7819e7c71bab7ae70bd3f08b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8224
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
2023-03-13 20:30:59 +00:00
Vincent Ambo
43b0416bd8 fix(tvix/eval): more closely line up path resolution with cppnix
... except now the tests fail, but at least it works

Change-Id: I05e86c173f40533ae65548585c1ddaa200ac5235
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8214
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00
Vincent Ambo
c700776733 refactor(tvix/eval): VM struct no longer needs to be public
Change-Id: I93b485ddd280cc15fcbaecf4aed5fcd22e28a8a8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8212
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00
Vincent Ambo
939cebd0f1 fix(tvix/eval): implement cppnix JSON-serialisation semantics
This drops the usage of serde::Serialize, as the trait can not be used
to implement the correct semantics (function colouring!).

Instead, a manual JSON serialisation function is written which
correctly handles toString, outPath and other similar weirdnesses.

Unexpectedly, the eval-okay-tojson test from the C++ Nix test suite
now passes, too.

This fixes an issue where serialising data structures containing
derivations to JSON would fail.

Change-Id: I5c39e3d8356ee93a07eda481410f88610f6dd9f8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8209
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00
Vincent Ambo
1e37f8b52e feat(tvix/eval): give generators human-readable names
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 20:30:59 +00:00
Vincent Ambo
dfd0066de5 fix(tvix/eval): handle toJSON on attribute sets with outPath
These are serialised as the serialisation of the value of that field.

Change-Id: Ida51708b1f43ce09b0ec835f4e265918aa31dd09
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8205
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
2023-03-13 20:30:59 +00:00