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Included changes:
* users/aspen: explicitly use open-source nvidia driver
This now has to be specified explicitly, otherwise evaluation fails with an
error.
* users/aspen: nixfmt -> nixfmt-classic
* users/aspen: fixes for renamed packages & options
* users/tazjin: fixes for renamed packages & options
* 3p/overlays: remove cbtemulator patch (merged upstream)
* tvix/shell: remove unnecessary patches (merged upstream)
* 3p/rust-crates: mark libgit2_sys as broken
* users/Profpatsch: mark git-db as broken
* 3p/overlays: pick `mypaint` from stable channel
* tvix: fix comments that clippy doesn't like anymore
* tvix/glue: disable a misfiring clippy lint (applying its suggestion breaks
code below)
Change-Id: I6d3fc027694bbe7425a2d25dc53d65467a44f3b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12403
Tested-by: BuildkiteCI
Reviewed-by: aspen <root@gws.fyi>
Reviewed-by: Profpatsch <mail@profpatsch.de>
Autosubmit: tazjin <tazjin@tvl.su>
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This vector type has served us well for now, but it contains internal refcounts
which are incompatible with upcoming changes related to garbage collection.
The performance impact of this change within all benchmarks I ran was within the
margin of error:
[nix-shell:/tmp/perf]$ hyperfine "./before -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings"
Benchmark 1: ./u64 -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
Time (mean ± σ): 7.528 s ± 0.272 s [User: 6.578 s, System: 0.631 s]
Range (min … max): 7.160 s … 8.012 s 10 runs
nix-shell:/tmp/perf]$ hyperfine "./std-vec -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings"
Benchmark 1: ./std-vec -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
Time (mean ± σ): 7.515 s ± 0.178 s [User: 6.508 s, System: 0.652 s]
Range (min … max): 7.276 s … 7.861 s 10 runs
Change-Id: Ib95f871956e336a1e5771f6293583854b1efb276
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12197
Reviewed-by: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
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This replaces the OpCode enum with a new Op enum which is guaranteed to fit in a
single byte. Instead of carrying enum variants with data, every variant that has
runtime data encodes it into the `Vec<u8>` that a `Chunk` now carries.
This has several advantages:
* Less stack space is required at runtime, and fewer allocations are required
while compiling.
* The OpCode doesn't need to carry "weird" special-cased data variants anymore.
* It is faster (albeit, not by much). On my laptop, results consistently look
approximately like this:
Benchmark 1: ./before -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
Time (mean ± σ): 8.224 s ± 0.272 s [User: 7.149 s, System: 0.688 s]
Range (min … max): 7.759 s … 8.583 s 10 runs
Benchmark 2: ./after -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
Time (mean ± σ): 8.000 s ± 0.198 s [User: 7.036 s, System: 0.633 s]
Range (min … max): 7.718 s … 8.334 s 10 runs
See notes below for why the performance impact might be less than expected.
* It is faster while at the same time dropping some optimisations we previously
performed.
This has several disadvantages:
* The code is closer to how one would write it in C or Go.
* Bit shifting!
* There is (for now) slightly more code than before.
On performance I have the following thoughts at the moment:
In order to prepare for adding GC, there's a couple of places in Tvix where I'd
like to fence off certain kinds of complexity (such as mutating bytecode, which,
for various reaons, also has to be part of data that is subject to GC). With
this change, we can drop optimisations like retroactively modifying existing
bytecode and *still* achieve better performance than before.
I believe that this is currently worth it to pave the way for changes that are
more significant for performance.
In general this also opens other avenues of optimisation: For example, we can
profile which argument sizes actually exist and remove the copy overhead of
varint decoding (which does show up in profiles) by using more adequately sized
types for, e.g., constant indices.
Known regressions:
* Op::Constant is no longer printing its values in disassembly (this can be
fixed, I just didn't get around to it, will do separately).
Change-Id: Id9b3a4254623a45de03069dbdb70b8349e976743
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12191
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
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Per https://nnethercote.github.io/perf-book/hashing.html, we have
basically no reason to use the default hasher over a faster,
non-DoS-resistant hasher. This gives a nice perf boost basically for
free:
hello outpath time: [704.76 ms 714.91 ms 725.63 ms]
change: [-7.2391% -6.1018% -4.9189%] (p = 0.00 < 0.05)
Performance has improved.
Change-Id: If5587f444ed3af69f8af4eead6af3ea303b4ae68
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12046
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>
Autosubmit: aspen <root@gws.fyi>
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This was made unnecessary in c92d06271 (feat(tvix/eval): drop
LightSpan::Delayed, 2023-12-08) because it didn't improve benchmarks as
much as expected and has been vestigial since; this continues the
cleanup by just removing it altogether
Change-Id: I21ec7ae9b52a5cccd2092696a5a87f658194d672
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11949
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
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There's other places where unexpected arguments can be provided, like
in builtins.
Make space for that error type.
Change-Id: Ic831497a3a1dd36a3a184bedadcf1374bf0ae6db
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11876
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
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In places where we want to extend context with that from another
NixString, use take_context() to split it off, then call .extend(),
making use of IntoIterator to avoid a bunch of clones.
Change-Id: I2460141a3ed776c64c36132b2203b6a1d710b922
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11705
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: edef <edef@edef.eu>
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- //tvix: address new clippy lints
- //users/tazjin: Satisfy gonic module's new need for a playlist folder.
- //users/aspen/games: adjust for changed location of df's default
init.txt and d_init.txt.
Change-Id: I00a2adb506ae866206fb6f88c39c9a6af320380f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11509
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: aspen <root@gws.fyi>
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Previously, Nix strings were represented as a Box (within Value)
pointing to a tuple of an optional context, and another Box pointing to
the actual string allocation itself. This is pretty inefficient, both in
terms of memory usage (we use 48 whole bytes for a None context!) and in
terms of the extra indirection required to get at the actual data. It
was necessary, however, because with native Rust DSTs if we had
something like `struct NixString(Option<NixContext>, BStr)` we could
only pass around *fat* pointers to that value (with the length in the
pointer) and that'd make Value need to be bigger (which is a waste of
both memory and cache space, since that memory would be unused for all
other Values).
Instead, this commit implements *manual* allocation of a packed string
representation, with the length *in the allocation* as a field past the
context. This requires a big old pile of unsafe Rust, but the payoff is
clear:
hello outpath time: [882.18 ms 897.16 ms 911.23 ms]
change: [-15.143% -13.819% -12.500%] (p = 0.00 < 0.05)
Performance has improved.
Fortunately this change can be localized entirely within
value/string.rs, since we were abstracting things out nicely.
Change-Id: Ibf56dd16c9c503884f64facbb7f0ac596463efb6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10852
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: aspen <root@gws.fyi>
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With this change it's no longer necessary to track the SourceCode
struct separately from the evaluation for error reporting: It's just
stored directly in the errors.
This also ends up resolving an issue in compiler::bindings, where we
cloned the Arc containing file references way too often. In fact those
clones probably compensate for all additional SourceCode clones during
error construction now.
Change-Id: Ice93bf161e61f8ea3d48103435e20c53e6aa8c3a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10986
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
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This is now the only enum variant for Value that is larger than 8
bytes (it's 16 bytes), so boxing it (especially since it's not
perf-critical) allows us to get the Value size down to only 16 bytes!
Change-Id: I98598e2b762944448bef982e8ff7da6d6683c4aa
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10798
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: aspen <root@gws.fyi>
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This reverts commit d3d41552cf1f6485f8ebc597a2128a0d15b030a5.
This was well-intentioned, but now the boxed Path values are actually
the *largest* Value enum variants, at 16 bytes (because they're
fat-pointers, with a len) instead of 8 bytes like all the other values.
Having the double reference is a reasonable price to pay (it seems; more
benchmarks may end up disagreeing) for a smaller Value repr.
Change-Id: I0d3e84f646c8f5ffd0b7259c4e456637eea360f7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10797
Tested-by: BuildkiteCI
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
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Storing a full BString here incurs the extra overhead of the capacity
for the inner byte-vector, which we basically never use as Nix strings
are immutable (and we don't do any mutation / sharing analysis).
Switching to a Box<BStr> cuts us from 72 bytes to 64 bytes per
string (and there are a lot of strings!)
Change-Id: I11f34c14a08fa02759f260b1c78b2a2b981714e4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10794
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
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Correctly propagate the case where the *key* of an attrset is a
Value::Catchable (eg { "${builtins.throw "c"}" = "b"; }) in
`NixAttrs::construct`, by converting the return type to
`Result<Result<Self, CatchableErrorKind>, ErrorKind>` (ugh!!) and
correctly handling that everywhere (including an `expect` in the
Deserialize impl for NixAttrs, since afaict this is impossible to hit
when deserializing from stuff like JSON).
Change-Id: Ic4bc611fbfdab27c0bd8a40759689a87c4004a17
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10786
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
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NixString is *quite* large - like 80 bytes - because of the extra
capacity value for BString and because of the context. We want to keep
Value small since we're passing it around a lot, so let's box the
NixString inside Value::String to save on some memory, and make cloning
ostensibly a little cheaper
Change-Id: I343c8b4e7f61dc3dcbbaba4382efb3b3e5bbabb2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10729
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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PathBuf internally contains a heap pointer (an OsString), so we were in
effect double-boxing here. Removing the extra layer by making
Tvix::Value represented by a Box<Path> rather than a Box<PathBuf> saves
us an indirection, while still avoiding the extra memory overhead of the
capacity which was the reason we were boxing PathBuf in the first place.
Change-Id: I8c185b9d4646161d1921917f83e87421496a3e24
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10725
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
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C++ nix uses C-style zero-terminated char pointers to represent strings
internally - however, up to this point, tvix has used Rust `String` and
`str` for string values. Since those are required to be valid utf-8, we
haven't been able to properly represent all the string values that Nix
supports.
To fix that, this change converts the internal representation of the
NixString struct from `Box<str>` to `BString`, from the `bstr` crate -
this is a wrapper around a `Vec<u8>` with extra functions for treating
that byte vector as a "morally string-like" value, which is basically
exactly what we need.
Since this changes a pretty fundamental assumption about a pretty core
type, there are a *lot* of changes in a lot of places to make this work,
but I've tried to keep the general philosophy and intent of most of the
code in most places intact. Most notably, there's nothing that's been
done to make the derivation stuff in //tvix/glue work with non-utf8
strings everywhere, instead opting to just convert to String/str when
passing things into that - there *might* be something to be done there,
but I don't know what the rules should be and I don't want to figure
them out in this change.
To deal with OS-native paths in a way that also works in WASM for
tvixbolt, this also adds a dependency on the "os_str_bytes" crate.
Fixes: b/189
Fixes: b/337
Change-Id: I5e6eb29c62f47dd91af954f5e12bfc3d186f5526
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10200
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
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Don't restrict to a Box<dyn EvalIO>.
There's still one or two places where we do restrict, this will be
solved by b/262.
Change-Id: Ic8d927d6ea81fa12d90b1e4352f35ffaafbd1adf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10639
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
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We want to handle bottoms in a consistent fashion. Previously this was
handled by repetitive is_catchable checks, which were not consistently
present.
Change-Id: I9614c479cc6297d1f64efba22b620a26e2a96802
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10485
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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A bunch of operations in Tvix are not aware of catchable values
and does not propagate them.
In the meantime, as we wait for a better solution, we just offer this
commit for moving the needle.
Change-Id: Ic3f0e1550126b0847b597dfc1402c35e0eeef469
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10473
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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We just perform union of contexts of every pieces.
Change-Id: Ief925c1818cd8bbec0503e9c625b0630feebfdda
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10432
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: raitobezarius <tvl@lahfa.xyz>
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We make a case for adding a `reject_context` `CoercionKind` here.
It does happen during concatenation actually for path concats.
Change-Id: I0c196aad917550b9bcd0896cd2127a94f8181ffb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10444
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: raitobezarius <tvl@lahfa.xyz>
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In the past, we had `emit_warning` be no-op and we used `push_warnings` exclusively
but as we have consumers of this function, we need it to work somewhat.
Change-Id: I78a5ece199a473dec9ef5ea1fae60b36e35137b8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10477
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
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Change-Id: I13d7ce0c7328a8e6fbc6d2c4ff5c4fe6095b96ea
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10357
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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Change-Id: I92d58ef216d7e0766af70f019b3dcd445284a95d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10344
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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I'm still trying to work out the exact stack invariants for tvix.
We really should add assertions for them; getting the stack messed
up is no fun. This commit adds one simple assertion. It also adds
a missing stack-push (my mistake) in one place, which was uncovered
by the assertion.
Change-Id: I9d8b4bd1702d954e325832c5935b0d7e3eb68422
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10369
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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The default behavior of string coercion in C++ Nix is to weakly coerce
and import to store if necessary. There is a flag to make it strongly
coerce (coerceMore) and a flag that controls whether path values have
the corresponding file/directory imported into the store before
returning the (store) path as a string (copyToStore). We need to
implement our equivalent to the copyToStore (import_paths) flag for the
benefit of weak coercions that don't import into the store (dirOf,
baseNameOf, readFile, ...) and strong coercions that don't import into
the store (toString).
This makes coerce_to_string as well as CoercionKind weirder and more
versatile, but prevents us from reimplementing parts of the coercion
logic constantly as can be seen in the case of baseNameOf.
Note that it is not possible to test this properly in //tvix/eval tests
due to the lack of an appropriate EvalIO implementation being available.
Tests should be added to //tvix/glue down the line.
Change-Id: I8fb8ab99c7fe08e311d2ba1c36960746bf22f566
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10361
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: Adam Joseph <adam@westernsemico.com>
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This matches the behavior of C++ Nix more closely where the decision is
made based on the first type based to ExprConcatStrings:
https://github.com/NixOS/nix/blob/1f93fa2ed29ff0ba92bfa58995232668187fb0d0/src/libexpr/eval.cc#L1967-L2025
Note that this doesn't make a difference in any successful
evaluation (at least to my knowledge), but ensures that our error
messages will match C++ Nix more closely, e.g. in the case of
`1 + "string"`.
Change-Id: I8059930788f9c8d98baf98e3d93d8a060ef961f2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10360
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
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Change-Id: Icf328649fd70bdf0fc3ba6cd7754ae29735f11f7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10035
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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This commit fixes out `?` operator so it correctly propagates
catchables.
Change-Id: Iebaa153a8492101ee3ddd29893c98730ff331547
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10317
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Previously, using a catchable as either argument of OpAttrsSelect
would result in an unrecoverable error. This commit matches cppnix
behavior by propagating the catchable.
Change-Id: I4877f4068ec2b823225f185290693c101d0b9c9e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10303
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
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When attempting to call a Value, if it is a Value::Catchable we must
not cause an uncatchable failure. This commit simply reuses the
Value::Catchable as the result of attempting to call it. This is
safe because nix is designed so that nix code cannot distinguish
between different catchable failures -- they all look the same to
the interpreted code.
This fixes b/351.
Change-Id: Ibf763a08753e541843626182ff59fdbf15ea2959
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10300
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Fixes b/347.
Change-Id: Icad0251884d4d8adcdf8d690b91385bf4896f9c8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10294
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
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Fixes b/346.
Change-Id: I277121d2363e605ebe09651ed9440fe1bc126c8c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10292
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
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This commit adds Opcode::OpJumpIfCatchable, which can be inserted
ahead of most VM operations which expect a boolean on the stack, in
order to handle catchables in branching position properly.
Other than remembering to patch the jump, no other changes should be
required.
This commit also fixes b/343 by emitting this new opcode when
compiling if-then-else. There are probably other places where we
need to do the same thing.
Change-Id: I48de3010014c0bbeba15d34fc0d4800e0bb5a1ef
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10288
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
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After this commit, the only non-builtins uses of generators are:
- coerce_to_string() uses generators::request_enter_lambda()
- Thunk::force() uses generators::request_enter_lambda()
That's it! Once those two are taken care of, GenCo can become an
implementation detail of `builtins::BuiltinGen`. No more crazy
nonlocal flow control within the interpreter: if you've got a GenCo
floating around in your code it's because you're writing a builtin,
which isn't part of the core interpreter. The interpreter won't
need GenCos to talk to itself anymore.
Technically generators::request_path_import() is also used by
coerce_to_string(), but that's just because the io_handle happens to
be part of the VM. There's no recursion-depth issue there, so the
call doesn't need to go through the generator mechanism
(request_path_import() doesn't call back to the interpreter!)
Change-Id: I83ce5774d49b88fdafdd61160975b4937a435bb0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10256
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
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This commit implements deep_force() nonrecursively, by maintaining
an explicit stack rather than using the call stack for recursion.
As an added bonus, we don't need to pass around the SharedThunkSet
anymore, and can in fact completely eliminate SharedThunkSet.
Change-Id: I7c4f59f37834d451a28bf6be317eb0a90eac4ee6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10252
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Adam Joseph <adam@westernsemico.com>
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LightSpan::Delayed was introduced in commit
bf286a54bc2ac5eeb78c3d5c5ae66e9af24d74d4 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
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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>
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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>
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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
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Relates to b/321.
Change-Id: I37284f89b186e469eb432e2bbedb37aa125a6ad4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9961
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>
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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
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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>
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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>
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HashMap already is on the heap.
Change-Id: I53763e17469359e85862f297b5c2e7c0d8c3a980
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9104
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
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Change-Id: Ia04778391c198fde21da217bf697aa40157898b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8846
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
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I've noticed this behavior when writing the admittedly cursed test case
included in this CL. Alternatively we could use some sort of machinery
using `builtins.trace`, but I don't think we capture stderr anywhere.
I've elected to put this into the eval cache itself while C++ Nix does
it in builtins.import already, namely via `realisePath`. We don't have
an equivalent for this yet, since we don't support any kind of IfD, but
we could revise that later. In any case, it seems good to encapsulate
`ImportCache` in this way, as it'll also allow using file hashes as
identifiers, for example.
C++ Nix also does our equivalent of canon_path in `builtins.import`
which we still don't, but I suspect it hardly makes a difference.
Change-Id: I05004737ca2458a4c67359d9e7d9a2f2154a0a0f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8839
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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When dealing with a formal argument in a function argument pattern that
has a default expression, there are two different things that can happen
at runtime: Either we select its value from the passed attribute
successfully or we need to use the default expression. Both of these may
be thunks and both of these may need finalisers. However, in the former
case this is taken care of elsewhere, the value will always be finalised
already if necessary. In the latter case we may need to finalise the
thunk resulting from the default expression. However, the thunk
corresponding to the expression may never end up in the local's stack
slot. Since finalisation goes by stack slot (and not constants), we need
to prevent a case where we don't fall back to the default expression,
but finalise anyways.
Previously, we worked around this by making `OpFinalise` ignore
non-thunks. Since finalisation of already evaluated thunks still
crashed, the faulty compilation of function pattern arguments could
still cause a crash.
As a new approach, we reinstate the old behavior of `OpFinalise` to
crash whenever encountering something that is either not a thunk or
doesn't need finalisation. This can also help catching (similar)
miscompilations in the future. To then prevent the crash, we need to
track whether we have fallen back or not at runtime. This is done using
an additional phantom on the stack that holds a new `FinaliseRequest`
value. When it comes to finalisation we check this value and
conditionally execute `OpFinalise` based on its value.
Resolves b/261 and b/265 (partially).
Change-Id: Ic04fb80ec671a2ba11fa645090769c335fb7f58b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8705
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
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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>
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