From 6c1948a71a7a52978a3ded23e242d664a5f097de Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Sun, 28 Aug 2022 16:50:46 +0300 Subject: feat(tvix/eval): detect deferred upvalue capturing Uses the threaded through slot offset to determine whether initialisation of a captured local upvalue must be defered to a later point where all values of a scope are available. This adds a new data representation to the opcode for this situation, but the equivalent runtime handling is not yet implemented. This is in part because there is more compiler machinery needed to find the resolution point. Change-Id: Ifd0c393f76abfe6e2d91483faf0f58947ab1dedc Reviewed-on: https://cl.tvl.fyi/c/depot/+/6329 Reviewed-by: sterni Tested-by: BuildkiteCI --- tvix/eval/src/compiler/mod.rs | 19 ++++++++++++++++--- tvix/eval/src/opcode.rs | 1 + tvix/eval/src/vm.rs | 5 +++++ 3 files changed, 22 insertions(+), 3 deletions(-) diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs index 0f22936f1c..85a2309eb3 100644 --- a/tvix/eval/src/compiler/mod.rs +++ b/tvix/eval/src/compiler/mod.rs @@ -122,7 +122,7 @@ impl Compiler { ast::Expr::LetIn(let_in) => self.compile_let_in(let_in), ast::Expr::Ident(ident) => self.compile_ident(ident), ast::Expr::With(with) => self.compile_with(with), - ast::Expr::Lambda(lambda) => self.compile_lambda(lambda), + ast::Expr::Lambda(lambda) => self.compile_lambda(slot, lambda), ast::Expr::Apply(apply) => self.compile_apply(apply), // Parenthesized expressions are simply unwrapped, leaving @@ -778,7 +778,7 @@ impl Compiler { self.end_scope(); } - fn compile_lambda(&mut self, node: ast::Lambda) { + fn compile_lambda(&mut self, slot: Option, node: ast::Lambda) { // Open new lambda context in compiler, which has its own // scope etc. self.contexts.push(LambdaCtx::new()); @@ -833,9 +833,22 @@ impl Compiler { self.chunk().push_op(OpCode::OpClosure(closure_idx)); for upvalue in compiled.scope.upvalues { match upvalue { - Upvalue::Stack(idx) => { + Upvalue::Stack(idx) if slot.is_none() => { self.chunk().push_op(OpCode::DataLocalIdx(idx)); } + + Upvalue::Stack(idx) => { + // If the upvalue slot is located *after* the + // closure, the upvalue resolution must be + // deferred until the scope is fully initialised + // and can be finalised. + if slot.unwrap() < idx.0 { + self.chunk().push_op(OpCode::DataDeferredLocal(idx)); + } else { + self.chunk().push_op(OpCode::DataLocalIdx(idx)); + } + } + Upvalue::Upvalue(idx) => { self.chunk().push_op(OpCode::DataUpvalueIdx(idx)); } diff --git a/tvix/eval/src/opcode.rs b/tvix/eval/src/opcode.rs index 5f1f33f2b3..12a76d368e 100644 --- a/tvix/eval/src/opcode.rs +++ b/tvix/eval/src/opcode.rs @@ -115,6 +115,7 @@ pub enum OpCode { // The VM skips over these by advancing the instruction pointer // according to the count. DataLocalIdx(StackIdx), + DataDeferredLocal(StackIdx), DataUpvalueIdx(UpvalueIdx), DataDynamicIdx(ConstantIdx), DataDynamicAncestor(UpvalueIdx), diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs index 316732dba0..33ea81087f 100644 --- a/tvix/eval/src/vm.rs +++ b/tvix/eval/src/vm.rs @@ -426,6 +426,10 @@ impl VM { closure.push_upvalue(value); } + OpCode::DataDeferredLocal(_idx) => { + todo!("deferred local initialisation") + } + _ => panic!("compiler error: missing closure operand"), } } @@ -434,6 +438,7 @@ impl VM { // Data-carrying operands should never be executed, // that is a critical error in the VM. OpCode::DataLocalIdx(_) + | OpCode::DataDeferredLocal(_) | OpCode::DataUpvalueIdx(_) | OpCode::DataDynamicIdx(_) | OpCode::DataDynamicAncestor(_) => { -- cgit 1.4.1