refactor(tvix/eval): Box Value::String r/7467

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>

2 files changed, 8 insertions, 8 deletions

diff --git a/tvix/eval/src/compiler/bindings.rs b/tvix/eval/src/compiler/bindings.rs
index a3d7c6fbfb..236b9dd2c3 100644
--- a/tvix/eval/src/compiler/bindings.rs
+++ b/tvix/eval/src/compiler/bindings.rs
@@ -361,7 +361,7 @@ impl Compiler<'_> {
 
                         // Place key on the stack when compiling attribute sets.
                         if kind.is_attrs() {
-                            self.emit_constant(Value::String(name.as_str().into()), &attr);
+                            self.emit_constant(name.as_str().into(), &attr);
                             let span = self.span_for(&attr);
                             self.scope_mut().declare_phantom(span, true);
                         }
@@ -569,7 +569,7 @@ impl Compiler<'_> {
 
                 KeySlot::Static { slot, name } => {
                     let span = self.scope()[slot].span;
-                    self.emit_constant(Value::String(name.as_str().into()), &span);
+                    self.emit_constant(name.as_str().into(), &span);
                     self.scope_mut().mark_initialised(slot);
                 }
 
@@ -593,7 +593,7 @@ impl Compiler<'_> {
                         c.compile(s, namespace.clone());
                         c.emit_force(&namespace);
 
-                        c.emit_constant(Value::String(name.as_str().into()), &span);
+                        c.emit_constant(name.as_str().into(), &span);
                         c.push_op(OpCode::OpAttrsSelect, &span);
                     })
                 }
@@ -685,7 +685,7 @@ impl Compiler<'_> {
         // (OpAttrs consumes all of these locals).
         self.scope_mut().end_scope();
 
-        self.emit_constant(Value::String("body".into()), node);
+        self.emit_constant("body".into(), node);
         self.push_op(OpCode::OpAttrsSelect, node);
     }
 
@@ -730,7 +730,7 @@ impl Compiler<'_> {
                 if self.has_dynamic_ancestor() {
                     self.thunk(slot, node, |c, _| {
                         c.context_mut().captures_with_stack = true;
-                        c.emit_constant(Value::String(ident.into()), node);
+                        c.emit_constant(ident.into(), node);
                         c.push_op(OpCode::OpResolveWith, node);
                     });
                     return;
diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs
index 0fa3d41393..4a7b5fd5ba 100644
--- a/tvix/eval/src/compiler/mod.rs
+++ b/tvix/eval/src/compiler/mod.rs
@@ -369,7 +369,7 @@ impl Compiler<'_> {
 
             ast::LiteralKind::Uri(u) => {
                 self.emit_warning(node, WarningKind::DeprecatedLiteralURL);
-                Value::String(u.syntax().text().into())
+                Value::from(u.syntax().text())
             }
         };
 
@@ -458,7 +458,7 @@ impl Compiler<'_> {
                 }
 
                 ast::InterpolPart::Literal(lit) => {
-                    self.emit_constant(Value::String(lit.as_str().into()), parent_node);
+                    self.emit_constant(Value::from(lit.as_str()), parent_node);
                 }
             }
         }
@@ -1360,7 +1360,7 @@ impl Compiler<'_> {
     /// several operations related to attribute sets, where
     /// identifiers are used as string keys.
     fn emit_literal_ident(&mut self, ident: &ast::Ident) {
-        self.emit_constant(Value::String(ident.clone().into()), ident);
+        self.emit_constant(Value::String(Box::new(ident.clone().into())), ident);
     }
 
     /// Patch the jump instruction at the given index, setting its