From f68c76d07daf9794797b1056ce39e8e1bdeca8e4 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Tue, 6 Sep 2022 17:44:32 +0300 Subject: fix(tvix/eval): account for attrset temporaries during construction The temporaries left on the stack as operands to `OpAttrs` must be accounted for in the locals array in order for operations within them to receive correct slots. Some test cases that were previously broken have been added. Change-Id: Ib52b629bbdf7931f63fd45a45af1073022da923c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6468 Tested-by: BuildkiteCI Reviewed-by: sterni --- tvix/eval/src/compiler/mod.rs | 49 +++++++++++++++++++++- .../tests/tvix_tests/eval-okay-thunked-with.exp | 1 + .../tests/tvix_tests/eval-okay-thunked-with.nix | 7 ++++ .../tvix_tests/eval-okay-with-in-dynamic-key.exp | 1 + .../tvix_tests/eval-okay-with-in-dynamic-key.nix | 12 ++++++ 5 files changed, 68 insertions(+), 2 deletions(-) create mode 100644 tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.exp create mode 100644 tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.nix create mode 100644 tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.exp create mode 100644 tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.nix (limited to 'tvix/eval/src') diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs index e119c866bc49..b6a3f329a0d6 100644 --- a/tvix/eval/src/compiler/mod.rs +++ b/tvix/eval/src/compiler/mod.rs @@ -473,6 +473,8 @@ impl Compiler<'_, '_> { // First emit the identifier itself (this // becomes the new key). self.emit_literal_ident(&ident); + let ident_span = self.span_for(&ident); + self.scope_mut().declare_phantom(ident_span, true); // Then emit the node that we're inheriting // from. @@ -482,22 +484,27 @@ impl Compiler<'_, '_> { // instruction followed by a merge, rather // than pushing/popping the same attrs // potentially a lot of times. - self.compile(slot, from.expr().unwrap()); + let val_idx = self.scope_mut().declare_phantom(ident_span, false); + self.compile(val_idx, from.expr().unwrap()); self.emit_force(&from.expr().unwrap()); self.emit_literal_ident(&ident); self.push_op(OpCode::OpAttrsSelect, &ident); + self.scope_mut().mark_initialised(val_idx); } } None => { for ident in inherit.idents() { + let ident_span = self.span_for(&ident); count += 1; // Emit the key to use for OpAttrs self.emit_literal_ident(&ident); + self.scope_mut().declare_phantom(ident_span, true); // Emit the value. self.compile_ident(slot, ident); + self.scope_mut().declare_phantom(ident_span, true); } } } @@ -519,6 +526,10 @@ impl Compiler<'_, '_> { todo!("recursive attribute sets are not yet implemented") } + // Open a scope to track the positions of the temporaries used + // by the `OpAttrs` instruction. + self.begin_scope(); + let mut count = self.compile_inherit_attrs(slot, node.inherits()); for kv in node.attrpath_values() { @@ -530,9 +541,32 @@ impl Compiler<'_, '_> { // runtime value representing the attribute path is // emitted. let mut key_count = 0; + let key_span = self.span_for(&kv.attrpath().unwrap()); + let key_idx = self.scope_mut().declare_phantom(key_span, false); + for fragment in kv.attrpath().unwrap().attrs() { + // Key fragments can contain dynamic expressions, + // which makes accounting for their stack slots very + // tricky. + // + // In order to ensure the locals are correctly cleaned + // up, we essentially treat any key fragment after the + // first one (which has a locals index that will + // become that of the final key itself) as being part + // of a separate scope, which results in the somewhat + // annoying setup logic below. + let fragment_slot = match key_count { + 0 => key_idx, + 1 => { + self.begin_scope(); + self.scope_mut().declare_phantom(key_span, false) + } + _ => self.scope_mut().declare_phantom(key_span, false), + }; + key_count += 1; - self.compile_attr(slot, fragment); + self.compile_attr(fragment_slot, fragment); + self.scope_mut().mark_initialised(fragment_slot); } // We're done with the key if there was only one fragment, @@ -543,15 +577,26 @@ impl Compiler<'_, '_> { OpCode::OpAttrPath(Count(key_count)), &kv.attrpath().unwrap(), ); + + // Close the temporary scope that was set up for the + // key fragments. + self.scope_mut().end_scope(); } // The value is just compiled as normal so that its // resulting value is on the stack when the attribute set // is constructed at runtime. + let value_span = self.span_for(&kv.value().unwrap()); + let value_slot = self.scope_mut().declare_phantom(value_span, false); self.compile(slot, kv.value().unwrap()); + self.scope_mut().mark_initialised(value_slot); } self.push_op(OpCode::OpAttrs(Count(count)), &node); + + // Remove the temporary scope, but do not emit any additional + // cleanup (OpAttrs consumes all of these locals). + self.scope_mut().end_scope(); } fn compile_select(&mut self, slot: LocalIdx, node: ast::Select) { diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.exp new file mode 100644 index 000000000000..d81cc0710eb6 --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.exp @@ -0,0 +1 @@ +42 diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.nix new file mode 100644 index 000000000000..6f32660c4c33 --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-thunked-with.nix @@ -0,0 +1,7 @@ +# Creates a `with` across multiple thunk boundaries. + +let + set = { + a = with { b = 42; }; b; + }; +in set.a diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.exp new file mode 100644 index 000000000000..d81cc0710eb6 --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.exp @@ -0,0 +1 @@ +42 diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.nix new file mode 100644 index 000000000000..c44455a5bf83 --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-with-in-dynamic-key.nix @@ -0,0 +1,12 @@ +# Tests correct tracking of stack indices within construction of an +# attribute set. Dynamic keys can be any expression, so something that +# is extremely sensitive to stack offsets (like `with`) can be tricky. + +let + set1 = { key = "b"; }; + set2 = { + a = 20; + ${with set1; key} = 20; + ${with { key = "c"; }; key} = 2; + }; +in set2.a + set2.b + set2.c -- cgit 1.4.1