LightSpan::Delayed was introduced in commit
bf286a54bc which claimed that "This
reduces the eval time for `builtins.length (builtins.attrNames
(import <nixpkgs> {}))` by *one third*!"
I am unable to reproduce this result. In fact, dropping the
LightSpan::Delayed variant of the enum makes eval of the same
expression slightly faster! I also tried a large evaluation
(pkgsCross...hello) and got similar results: slightly faster,
slightly less memory. See git footers.
I suspect that there was some unrelated horrific inefficiency that
has since been fixed. The avoided computation in `get_span()` is
nothing more than a binary search! If this were in fact a major
performance issue we could simply precompute the mapping from
CodeIdx to Span when the Chunk becomes immutable (i.e. at the end of
the compilation process, when compiler backtracking is no longer a
concern). Since a Span is just 64 bits this is not a space issue,
and since binary search is much simpler than compiling Nix
expressions it isn't a performance issue either.
Technically there is no longer any reason to have LightSpan since it
is now a single-variant enum. However there is no rush to remove
it, since Rust will optimize its representation into the same thing
you'd get if you replaced LightSpan by Span.
Prev-Benchmark: {"nixpkgs-attrnames":{"kbytes":"233824","system":"0.32","user":"2.02"}}
This-Benchmark: {"nixpkgs-attrnames":{"kbytes":"230192","system":"0.29","user":"2.00"}}
Prev-Benchmark: {"pkgsCross.aarch64-multiplatform.hello.outPath":{"kbytes":"458936","system":"0.73","user":"5.36"}}
This-Benchmark: {"pkgsCross.aarch64-multiplatform.hello.outPath":{"kbytes":"451808","system":"0.53","user":"5.10"}}
Change-Id: Ib9e04806850aa1fc4e66e2a042703986440a7b4e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10254
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
This is just a alias for Result<_, io::Error>, but shorter.
Change-Id: I7c22f61b85e3014885a747b5c1e5abd11b0ef17d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10327
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This commit fixes b/338 by properly propagating catchables through
comparison operations.
Change-Id: I6b0283a40f228ecf9a6398d24c060bdacb1077cf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10221
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Commit 05f42519b5 fixed b/281 by
establishing a hygiene regimen to partition *catchable* errors
(i.e. those which tryEval can detect) from all other errors, like
internal VM failures or I/O errors (which Nix must not be allowed to
detect, since these errors are fundamentally impure).
Unfotunately there are still cases where tvix assumes that anything
other than Value::Bool means it should panic!(). I found another
one, and added a test case for it in:
eval_okay_src_tests_tvix_tests_eval_okay_compare_ordering_catchable_nix
Not yet passing.
Change-Id: I69c62ed9ea5c8f81870e8de5c5fe12dcde849763
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10220
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
This commit rewrites Value::nix_cmp_ordering() into an equivalent
nonrecursive form. Except for calls to Thunk::force(), the new form
no longer uses generators, and is async only because of the fact
that it calls Thunk::force().
I originally believed that this commit would make evaluation faster.
In fact it is slightly slower. I believe this is due to the added
vec![] allocation. I am investigating.
Prev-Nixpkgs-Benchmark: {"attrpath":"pkgsCross.aarch64-multiplatform.hello.outPath","peak-kbytes":"460048","system-seconds":"0.68","user-seconds":"5.73"}
This-Nixpkgs-Benchmark: {"attrpath":"pkgsCross.aarch64-multiplatform.hello.outPath","peak-kbytes":"460224","system-seconds":"0.67","user-seconds":"5.84"}
Change-Id: Ic627bc220d9c5aa3c5e68b9b8bf199837cd55af5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10212
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
This is part of a fix for b/338.
We should never use PartialOrd::partial_cmp().
All Nix types except floats are obviously totally-ordered. In
addition, it turns out that because Nix treats division by zero
rather than producing a NaN, and because it does not support
"negative zero", even floats are in fact totally ordered in Nix.
Therefore, every call to PartialOrd::partial_cmp() in tvix is an
error. We have to *implement* this function, but we should never
call it on built-in types.
Moreover, nix_cmp_ordering() currently returns an Option<Ordering>.
I'm not sure what was going on there, since it's impossible for it
to return None. This commit fixes it to return simply Ordering
rather than Option<Ordering>.
Change-Id: If5c084164cf19cfb38c5a15554c0422faa5f895d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10218
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
This commit rewrites Value::nix_eq() into an equivalent. Except for
calls to Thunk::force(), the new form no longer uses generators, and
is async only because of the fact that it calls Thunk::force().
I believed that the nonrecursive form would be faster. It is, in
fact, slightly slower. I believe this is due to the vec![]
allocation; I am investigating.
Prev-Nixpkgs-Benchmark: {"attrpath":"pkgsCross.aarch64-multiplatform.hello.outPath","peak-kbytes":"459068","system-seconds":"0.71","user-seconds":"5.39"}
This-Nixpkgs-Benchmark: {"attrpath":"pkgsCross.aarch64-multiplatform.hello.outPath","peak-kbytes":"460048","system-seconds":"0.68","user-seconds":"5.73"}
Change-Id: I10f4868891e4b7475df13f0cbc41ec78dd985dd8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10118
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
This commit rewrites Thunk::force() so that it is not (directly)
self-recursive. It maintains a Vec of all the
previously-encountered thunks which point to the one it is currently
forcing, rather than recursively calling itself.
Benefits:
- Short term:
This commit saves the cost of a round-trip through the generator
machinery for the generators::request_force() which is removed by
this commit.
- Medium term:
Once a similar transformation has been applied to nix_cmp(),
nix_add(), nix_eq(), and coerce_to_string(), those four functions,
along with Thunk::force(), will make non-tail calls only to each
other. They can then be merged into a single tail-recursive
function which does not use the generator machinery at all:
enum Task { Cmp, Add, Eq, CoerceToString, Force};
fn Value::walk(task:Task, v1:Value, v2:Value) {
// ...
- Long term:
The long-term goal here is to use generators **only for builtins**
and [Marionette]-style remote control of the VM. In other words:
use `async` for things that actually involve concurrency. Calls
from the VM to builtins can then be blocking calls, because even
cppnix will overflow the stack if you make a MAX_STACK_DEPTH-deep
recursive call which passes through a builtin at every stack frame
(e.g. `{ func = builtins.sort (a: b: ... func ...) ...}`).
This way the inner "tight loop" of the interpreter doesn't pay the
costs of `async` and generators. These costs manifest in terms
of: performance, complex nonlocal control flow, and language
impediments (async Rust is a restricted subset of real Rust, and
is missing things like traits).
[Marionette]: https://firefox-source-docs.mozilla.org/testing/marionette/Intro.html
Change-Id: I6179b8abb2ea0492180fcb347f37595a14665777
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10039
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
If builtins.substring is invoked with (byte!!) offsets that aren't at
codepoint boundaries, return an error rather than panicking. This is
still incorrect (see b/337) but pushes the incorrectness forward a step.
Change-Id: I5a4261f2ff250874cd36489ef598dcf886669d04
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10199
Tested-by: BuildkiteCI
Autosubmit: grfn <grfn@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
This fixes a future clippy lint.
Change-Id: Ic830e94ef23595580c1037f10878c76bbb546dd9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10110
Tested-by: BuildkiteCI
Reviewed-by: Adam Joseph <adam@westernsemico.com>
This commit adds Thunk::unwrap_or_clone(), which uses
Rc::try_unwrap() to avoid cloning the Value out of a an Rc which has
only one strong reference.
Change-Id: Icacefe0c823dcddf046d90c0c5cd5ed59fe976d4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10037
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
Change-Id: Ibddaa111a5b7a86c42dbe153ae8e53f9a5601a54
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10112
Tested-by: BuildkiteCI
Reviewed-by: Adam Joseph <adam@westernsemico.com>
This *might* contain a fix for a clippy lint thrown by that crate.
Relates to b/321.
Change-Id: Ia7ebd3e26e0feb8bcc7a6c811b1e583f9016fd9e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9966
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>
Uses the standard library IntoIterator trait for the construction of
our iterators. Clippy complains about duplicating this.
While doing this, I opted to rename the `IntoIter` type into something
that is more useful to users, in case somebody ends up working with
these manually.
This fixes a clippy lint, and is related to b/321.
Change-Id: I851fde0d7b8b38d182343a0fd6d9f8dd2a33ee11
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9963
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>
Delays allocation (through cloning) of the values to be compared
until *after* the keys have been compared.
Change-Id: I7d68c27d7a0fbcdcc387db7c092bce50ca4b94ea
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9900
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Similar to `into_iter_sorted`, add a marker function for call sites
that want *borrowed* sorted iteration.
Change-Id: I7c6f14e1ac43fdb14b861b3da183eb5d12bba139
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9899
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
builtins.intersectAttrs is used a _lot_ in nixpkgs eval, for whatever
reason. We previously had a very inefficient implementation that would
allocate for each comparison. It stuck out like a sore thumb in perf
analysis.
This moves to a custom algorithm with two iterators, one for the left
and one for the right side, advancing them along the (borrowed) map
keys until a match is found and allocation is required.
I've not made any effort to reduce the verbosity of this code, I don't
think it's worth it.
On my machine this reduces the mean runtime of evaluating
`nixpkgs.emacs.outPath` by ~8%.
Change-Id: Ie506d82cb8d5f45909628f771a6b73e0eca16b27
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9898
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
The purpose of black_box is to actually prevent the compiler from being
able to optimize computation of the benchmarked function away.
To accomplish this, we need to actually *use* black_box to blackbox the
input data away, rather than the return type.
Change-Id: I5438982f57509fbf7b85034346a2739d76aef1fa
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9902
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
tempdir pulls in remove_dir_all 0.5.3 with
https://rustsec.org/advisories/RUSTSEC-2023-0018.html, and we use
tempfile everywhere else too, so let's just migrate to that.
Change-Id: I735ade7b65e12fc26e3d43ca95fcfa07fcc64642
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9565
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
This commit adds a test case for b/281.
Change-Id: I8dfbfc0ff636184d7882530d8aefb329a3af9e5c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9288
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: flokli <flokli@flokli.de>
This commit makes catchable errors a variant of Value.
The main downside of this approach is that we lose the ability to
use Rust's `?` syntax for propagating catchable errors.
Change-Id: Ibe89438d8a70dcec29e016df692b5bf88a5cad13
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9289
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
This commit creates a separate enum for "catchable" errors (the kind
that `builtins.tryEval` can detect).
Change-Id: Ie81d1112526d852255d9842f67045f88eab192af
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9287
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
There's some more left, but they've been renamed/refactored out of
sight.
Change-Id: I41579dedc74342b4c5f8cb39d2995b5b0c90b0f4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9372
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Autosubmit: flokli <flokli@flokli.de>
In cppnix 2.17, commit b72bc4a972fe568744d98b89d63adcd504cb586c, the
libexpr pretty-printing routine was fixed so that it would no longer
pretty-print attrsets with keywords in their attrnames incorrectly.
This commit implements the corresponding fix for tvix, fixes our
tests to work with cppnix>=2.17 oracles, and expands our test cases
to cover all the keywords.
Change-Id: I4b51389cd3a9c44babc8ab2a84b383b7b0b116ca
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9283
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Previously, compare_strict_eval_tests() was using Strictness::Lazy.
This appears to be a minor oversight from
0ab6494286.
This commit corrects that, by changing Strictness::Lazy to
Strictness::Strict.
Change-Id: Ia2389a5d30481cd322ed55230731340b795e5d87
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9282
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: sterni <sternenseemann@systemli.org>
replaceStrings would previously fail to replace the last character
in a string.
Change-Id: I43a7c960945350b2e7a5b731b7fdb617723eb38f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9151
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
This passes a unit value to the function.
Change-Id: I4df3ad8fb0f35c0f110cee3349971ae28ce2878c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9101
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
builtins.div ought to truncate towards zero so that
-(builtins.div a b) == builtins.div (-a) b
-(builtins.div a b) == builtins.div a (-b)
Change-Id: I8b7c08cd7f4fa8a1363c786d42c8d484f6cd133d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9006
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
