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feat(tvix/eval): nonrecursive nix_eq()

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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>
This commit is contained in:
Adam Joseph 2023-11-25 01:38:00 -08:00 • committed by clbot
parent 0c15a09b15
commit 72ece2e518
4 changed files with 169 additions and 147 deletions
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11
tvix/eval/src/value/thunk.rs
View file

@ -205,7 +205,14 @@ impl Thunk {
}
}
pub async fn force(mut myself: Thunk, co: GenCo, span: LightSpan) -> Result<Value, ErrorKind> {
pub async fn force(myself: Thunk, co: GenCo, span: LightSpan) -> Result<Value, ErrorKind> {
Self::force_(myself, &co, span).await
}
pub async fn force_(
mut myself: Thunk,
co: &GenCo,
span: LightSpan,
) -> Result<Value, ErrorKind> {
// This vector of "thunks which point to the thunk-being-forced", to
// be updated along with it, is necessary in order to write this
// function in iterative (and later, mutual-tail-call) form.
@ -261,7 +268,7 @@ impl Thunk {
// be turned into a tailcall to vm::execute_bytecode() by
// passing `also_update` to it.
let value =
generators::request_enter_lambda(&co, lambda, upvalues, light_span).await;
generators::request_enter_lambda(co, lambda, upvalues, light_span).await;
myself.0.replace(ThunkRepr::Evaluated(value));
continue;
}