5757e65f7a
emit (via debug!) scary message from `fn borrowck_mir` until basic prototype is in place. Gather children of move paths and set their kill bits in dataflow. (Each node has a link to the child that is first among its siblings.) Hooked in libgraphviz based rendering, including of borrowck dataflow state. doing this well required some refactoring of the code, so I cleaned it up more generally (adding comments to explain what its trying to do and how it is doing it). Update: this newer version addresses most review comments (at least the ones that were largely mechanical changes), but I left the more interesting revisions to separate followup commits (in this same PR).
63 lines
2.5 KiB
Rust
63 lines
2.5 KiB
Rust
// Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! The move-analysis portion of borrowck needs to work in an abstract
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//! domain of lifted Lvalues. Most of the Lvalue variants fall into a
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//! one-to-one mapping between the concrete and abstract (e.g. a
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//! field-deref on a local-variable, `x.field`, has the same meaning
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//! in both domains). Indexed-Projections are the exception: `a[x]`
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//! needs to be treated as mapping to the same move path as `a[y]` as
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//! well as `a[13]`, et cetera.
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//!
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//! (In theory the analysis could be extended to work with sets of
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//! paths, so that `a[0]` and `a[13]` could be kept distinct, while
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//! `a[x]` would still overlap them both. But that is not this
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//! representation does today.)
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use rustc::mir::repr::{Lvalue, LvalueElem};
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use rustc::mir::repr::{Operand, Projection, ProjectionElem};
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#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
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pub struct AbstractOperand;
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pub type AbstractProjection<'tcx> =
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Projection<'tcx, Lvalue<'tcx>, AbstractOperand>;
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pub type AbstractElem<'tcx> =
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ProjectionElem<'tcx, AbstractOperand>;
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pub trait Lift {
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type Abstract;
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fn lift(&self) -> Self::Abstract;
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}
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impl<'tcx> Lift for Operand<'tcx> {
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type Abstract = AbstractOperand;
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fn lift(&self) -> Self::Abstract { AbstractOperand }
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}
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impl<'tcx> Lift for LvalueElem<'tcx> {
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type Abstract = AbstractElem<'tcx>;
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fn lift(&self) -> Self::Abstract {
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match *self {
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ProjectionElem::Deref =>
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ProjectionElem::Deref,
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ProjectionElem::Field(ref f, ty) =>
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ProjectionElem::Field(f.clone(), ty.clone()),
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ProjectionElem::Index(ref i) =>
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ProjectionElem::Index(i.lift()),
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ProjectionElem::ConstantIndex {offset,min_length,from_end} =>
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ProjectionElem::ConstantIndex {
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offset: offset,
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min_length: min_length,
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from_end: from_end
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},
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ProjectionElem::Downcast(a, u) =>
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ProjectionElem::Downcast(a.clone(), u.clone()),
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}
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}
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}
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