feat(tvix/eval): implement initial compiler::optimiser module r/5602

This optimiser can rewrite some expressions into more efficient forms,
and warn users about those cases.

As a proof-of-concept, only some simple boolean comparisons are
supported for now.

Change-Id: I7df561118cfbad281fc99523e859bc66e7a1adcb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7766
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs
index d5afe47d73..2f4fc4da64 100644
--- a/tvix/eval/src/compiler/mod.rs
+++ b/tvix/eval/src/compiler/mod.rs
@@ -15,6 +15,7 @@
 
 mod bindings;
 mod import;
+mod optimiser;
 mod scope;
 
 use codemap::Span;
@@ -230,6 +231,8 @@ impl Compiler<'_> {
 // Actual code-emitting AST traversal methods.
 impl Compiler<'_> {
     fn compile(&mut self, slot: LocalIdx, expr: ast::Expr) {
+        let expr = optimiser::optimise_expr(self, expr);
+
         match &expr {
             ast::Expr::Literal(literal) => self.compile_literal(literal),
             ast::Expr::Path(path) => self.compile_path(slot, path),