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Move find_use stuff to it's own file
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src/librustc_mir/borrow_check/nll/explain_borrow/find_use.rs
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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT | ||
// file at the top-level directory of this distribution and at | ||
// http://rust-lang.org/COPYRIGHT. | ||
// | ||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
// option. This file may not be copied, modified, or distributed | ||
// except according to those terms. | ||
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use borrow_check::borrow_set::BorrowData; | ||
use borrow_check::nll::region_infer::RegionInferenceContext; | ||
use rustc::mir::visit::{MirVisitable, PlaceContext, Visitor}; | ||
use rustc::mir::{Local, Location, Mir}; | ||
use rustc_data_structures::fx::FxHashSet; | ||
use util::liveness::{self, DefUse, LivenessMode}; | ||
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crate fn regular_use<'gcx, 'tcx>( | ||
mir: &'gcx Mir, | ||
regioncx: &'tcx RegionInferenceContext, | ||
borrow: &'tcx BorrowData, | ||
start_point: Location, | ||
local: Local, | ||
) -> Option<Location> { | ||
let mut uf = UseFinder { | ||
mir, | ||
regioncx, | ||
borrow, | ||
start_point, | ||
local, | ||
liveness_mode: LivenessMode { | ||
include_regular_use: true, | ||
include_drops: false, | ||
}, | ||
}; | ||
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uf.find() | ||
} | ||
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crate fn drop_use<'gcx, 'tcx>( | ||
mir: &'gcx Mir, | ||
regioncx: &'tcx RegionInferenceContext, | ||
borrow: &'tcx BorrowData, | ||
start_point: Location, | ||
local: Local, | ||
) -> Option<Location> { | ||
let mut uf = UseFinder { | ||
mir, | ||
regioncx, | ||
borrow, | ||
start_point, | ||
local, | ||
liveness_mode: LivenessMode { | ||
include_regular_use: false, | ||
include_drops: true, | ||
}, | ||
}; | ||
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uf.find() | ||
} | ||
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struct UseFinder<'gcx, 'tcx> { | ||
mir: &'gcx Mir<'gcx>, | ||
regioncx: &'tcx RegionInferenceContext<'tcx>, | ||
borrow: &'tcx BorrowData<'tcx>, | ||
start_point: Location, | ||
local: Local, | ||
liveness_mode: LivenessMode, | ||
} | ||
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impl<'gcx, 'tcx> UseFinder<'gcx, 'tcx> { | ||
fn find(&mut self) -> Option<Location> { | ||
let mut stack = vec![]; | ||
let mut visited = FxHashSet(); | ||
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stack.push(self.start_point); | ||
while let Some(p) = stack.pop() { | ||
if !self.regioncx.region_contains_point(self.borrow.region, p) { | ||
continue; | ||
} | ||
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if !visited.insert(p) { | ||
continue; | ||
} | ||
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let block_data = &self.mir[p.block]; | ||
let (defined, used) = self.def_use(p, block_data.visitable(p.statement_index)); | ||
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if used { | ||
return Some(p); | ||
} else if !defined { | ||
if p.statement_index < block_data.statements.len() { | ||
stack.push(Location { | ||
statement_index: p.statement_index + 1, | ||
..p | ||
}); | ||
} else { | ||
stack.extend(block_data.terminator().successors().map(|&basic_block| { | ||
Location { | ||
statement_index: 0, | ||
block: basic_block, | ||
} | ||
})); | ||
} | ||
} | ||
} | ||
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None | ||
} | ||
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fn def_use(&self, location: Location, thing: &dyn MirVisitable<'tcx>) -> (bool, bool) { | ||
let mut visitor = DefUseVisitor { | ||
defined: false, | ||
used: false, | ||
local: self.local, | ||
liveness_mode: self.liveness_mode, | ||
}; | ||
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thing.apply(location, &mut visitor); | ||
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(visitor.defined, visitor.used) | ||
} | ||
} | ||
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struct DefUseVisitor { | ||
defined: bool, | ||
used: bool, | ||
local: Local, | ||
liveness_mode: LivenessMode, | ||
} | ||
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impl<'tcx> Visitor<'tcx> for DefUseVisitor { | ||
fn visit_local(&mut self, &local: &Local, context: PlaceContext<'tcx>, _: Location) { | ||
if local == self.local { | ||
match liveness::categorize(context, self.liveness_mode) { | ||
Some(DefUse::Def) => self.defined = true, | ||
Some(DefUse::Use) => self.used = true, | ||
None => (), | ||
} | ||
} | ||
} | ||
} |
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