/
dump_mir.rs
98 lines (86 loc) · 3.41 KB
/
dump_mir.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.
//! As part of generating the regions, if you enable `-Zdump-mir=nll`,
//! we will generate an annotated copy of the MIR that includes the
//! state of region inference. This code handles emitting the region
//! context internal state.
use std::io::{self, Write};
use super::{OutlivesConstraint, RegionInferenceContext};
// Room for "'_#NNNNr" before things get misaligned.
// Easy enough to fix if this ever doesn't seem like
// enough.
const REGION_WIDTH: usize = 8;
impl<'tcx> RegionInferenceContext<'tcx> {
/// Write out our state into the `.mir` files.
pub(crate) fn dump_mir(&self, out: &mut dyn Write) -> io::Result<()> {
writeln!(out, "| Free Region Mapping")?;
for region in self.regions() {
if self.definitions[region].is_universal {
let classification = self.universal_regions.region_classification(region).unwrap();
let outlived_by = self.universal_regions.regions_outlived_by(region);
writeln!(
out,
"| {r:rw$} | {c:cw$} | {ob}",
r = format!("{:?}", region),
rw = REGION_WIDTH,
c = format!("{:?}", classification),
cw = 8, // "External" at most
ob = format!("{:?}", outlived_by)
)?;
}
}
writeln!(out, "|")?;
writeln!(out, "| Inferred Region Values")?;
for region in self.regions() {
writeln!(
out,
"| {r:rw$} | {v}",
r = format!("{:?}", region),
rw = REGION_WIDTH,
v = self.region_value_str(region),
)?;
}
writeln!(out, "|")?;
writeln!(out, "| Inference Constraints")?;
self.for_each_constraint(&mut |msg| writeln!(out, "| {}", msg))?;
Ok(())
}
/// Debugging aid: Invokes the `with_msg` callback repeatedly with
/// our internal region constraints. These are dumped into the
/// -Zdump-mir file so that we can figure out why the region
/// inference resulted in the values that it did when debugging.
fn for_each_constraint(
&self,
with_msg: &mut dyn FnMut(&str) -> io::Result<()>,
) -> io::Result<()> {
for region in self.definitions.indices() {
let value = self.liveness_constraints.region_value_str(region);
if value != "{}" {
with_msg(&format!("{:?} live at {}", region, value))?;
}
}
let mut constraints: Vec<_> = self.constraints.iter().collect();
constraints.sort();
for constraint in &constraints {
let OutlivesConstraint {
sup,
sub,
locations,
} = constraint;
with_msg(&format!(
"{:?}: {:?} due to {:?}",
sup,
sub,
locations,
))?;
}
Ok(())
}
}