refactor(tvix/eval): wrap Builtin
type in a Box
This reduces the size of `Builtin` from 88 (!) bytes to 8, and as the largest variant of `Value`, the size of that type from 96 to 64. The next largest type is NixList, clocking in at 64 bytes. This has noticeable performance impact. In an implementation without disk I/O, evaluating nixpkgs.stdenv looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.151 s ± 0.003 s [User: 1.041 s, System: 0.109 s] Range (min … max): 1.147 s … 1.155 s 10 runs After this change, it looks like this: Benchmark 1: tvix -E '(import <nixpkgs> {}).stdenv.drvPath' Time (mean ± σ): 1.046 s ± 0.004 s [User: 0.954 s, System: 0.092 s] Range (min … max): 1.041 s … 1.053 s 10 runs Change-Id: I5ab7cc02a9a450c0227daf1f1f72966358311ebb Reviewed-on: https://cl.tvl.fyi/c/depot/+/8027 Tested-by: BuildkiteCI Reviewed-by: flokli <flokli@flokli.de>
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1 changed files with 30 additions and 20 deletions
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@ -33,6 +33,19 @@ pub struct BuiltinArgument {
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pub name: &'static str,
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}
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#[derive(Clone)]
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pub struct BuiltinRepr {
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name: &'static str,
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/// Array of arguments to the builtin.
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arguments: &'static [BuiltinArgument],
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/// Optional documentation for the builtin.
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documentation: Option<&'static str>,
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func: Rc<dyn BuiltinFn>,
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/// Partially applied function arguments.
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partials: Vec<Value>,
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}
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/// Represents a single built-in function which directly executes Rust
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/// code that operates on a Nix value.
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///
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@ -46,16 +59,12 @@ pub struct BuiltinArgument {
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/// "capture" the partially applied arguments, and are treated
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/// specially when printing their representation etc.
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#[derive(Clone)]
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pub struct Builtin {
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name: &'static str,
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/// Array of arguments to the builtin.
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arguments: &'static [BuiltinArgument],
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/// Optional documentation for the builtin.
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documentation: Option<&'static str>,
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func: Rc<dyn BuiltinFn>,
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pub struct Builtin(Box<BuiltinRepr>);
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/// Partially applied function arguments.
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partials: Vec<Value>,
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impl From<BuiltinRepr> for Builtin {
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fn from(value: BuiltinRepr) -> Self {
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Builtin(Box::new(value))
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}
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}
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impl Builtin {
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@ -65,36 +74,37 @@ impl Builtin {
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documentation: Option<&'static str>,
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func: F,
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) -> Self {
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Builtin {
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BuiltinRepr {
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name,
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arguments,
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documentation,
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func: Rc::new(func),
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partials: vec![],
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}
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.into()
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}
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pub fn name(&self) -> &'static str {
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self.name
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self.0.name
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}
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pub fn documentation(&self) -> Option<&'static str> {
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self.documentation
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self.0.documentation
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}
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/// Apply an additional argument to the builtin, which will either
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/// lead to execution of the function or to returning a partial
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/// builtin.
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pub fn apply(mut self, vm: &mut VM, arg: Value) -> Result<Value, ErrorKind> {
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self.partials.push(arg);
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self.0.partials.push(arg);
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if self.partials.len() == self.arguments.len() {
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for (idx, BuiltinArgument { strict, .. }) in self.arguments.iter().enumerate() {
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if self.0.partials.len() == self.0.arguments.len() {
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for (idx, BuiltinArgument { strict, .. }) in self.0.arguments.iter().enumerate() {
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if *strict {
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self.partials[idx].force(vm)?;
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self.0.partials[idx].force(vm)?;
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}
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}
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return (self.func)(self.partials, vm);
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return (self.0.func)(self.0.partials, vm);
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}
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// Function is not yet ready to be called.
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@ -104,13 +114,13 @@ impl Builtin {
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impl Debug for Builtin {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "builtin[{}]", self.name)
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write!(f, "builtin[{}]", self.0.name)
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}
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}
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impl Display for Builtin {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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if !self.partials.is_empty() {
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if !self.0.partials.is_empty() {
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f.write_str("<<primop-app>>")
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} else {
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f.write_str("<<primop>>")
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@ -121,6 +131,6 @@ impl Display for Builtin {
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/// Builtins are uniquely identified by their name
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impl PartialEq for Builtin {
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fn eq(&self, other: &Self) -> bool {
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self.name == other.name
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self.0.name == other.0.name
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}
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}
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