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authorAspen Smith <root@gws.fyi>2024-01-30T19·21-0500
committeraspen <root@gws.fyi>2024-02-01T21·08+0000
commit8caa097ba84f57515513d86621826556f2374fad (patch)
tree1eb7ecac8755b63c9907c870eaa6a16a6f87c71e /tvix/eval/src/chunk.rs
parent25f092002554fa53497fc7d844ae257832ad655a (diff)
feat(tvix/eval): Don't emit OpForce for non-thunk constants r/7463
In the compiler, skip emitting an OpForce if the last op was an
OpConstant for a non-thunk constant. This gives a small (~1% on my
machine) perf boost, eg when evaluating hello.outPath:

    ❯ hyperfine \
        "./before --no-warnings -E '(import <nixpkgs> {}).hello.outPath'" \
        "./after --no-warnings -E '(import <nixpkgs> {}).hello.outPath'"
    Benchmark 1: ./before --no-warnings -E '(import <nixpkgs> {}).hello.outPath'
      Time (mean ± σ):      1.151 s ±  0.022 s    [User: 1.003 s, System: 0.151 s]
      Range (min … max):    1.123 s …  1.184 s    10 runs

    Benchmark 2: ./after --no-warnings -E '(import <nixpkgs> {}).hello.outPath'
      Time (mean ± σ):      1.140 s ±  0.022 s    [User: 0.989 s, System: 0.152 s]
      Range (min … max):    1.115 s …  1.175 s    10 runs

    Summary
      ./after --no-warnings -E '(import <nixpkgs> {}).hello.outPath' ran
        1.01 ± 0.03 times faster than ./before --no-warnings -E '(import <nixpkgs> {}).hello.outPath'

Change-Id: I2105fd431d4bad699087907e16c789418e9a4062
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10714
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Diffstat (limited to 'tvix/eval/src/chunk.rs')
-rw-r--r--tvix/eval/src/chunk.rs10
1 files changed, 10 insertions, 0 deletions
diff --git a/tvix/eval/src/chunk.rs b/tvix/eval/src/chunk.rs
index b6fc6be5b99c..f1a35a6ce162 100644
--- a/tvix/eval/src/chunk.rs
+++ b/tvix/eval/src/chunk.rs
@@ -70,6 +70,11 @@ impl Chunk {
         self.spans[0].span
     }
 
+    /// Return a reference to the last op in the chunk, if any
+    pub fn last_op(&self) -> Option<&OpCode> {
+        self.code.last()
+    }
+
     /// Pop the last operation from the chunk and clean up its tracked
     /// span. Used when the compiler backtracks.
     pub fn pop_op(&mut self) {
@@ -90,6 +95,11 @@ impl Chunk {
         ConstantIdx(idx)
     }
 
+    /// Return a reference to the constant at the given [`ConstantIdx`]
+    pub fn get_constant(&self, constant: ConstantIdx) -> Option<&Value> {
+        self.constants.get(constant.0)
+    }
+
     // Span tracking implementation
 
     fn push_span(&mut self, span: codemap::Span, start: usize) {