1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#![deny(rustc::untranslatable_diagnostic)]
#![deny(rustc::diagnostic_outside_of_impl)]
//! 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 super::{OutlivesConstraint, RegionInferenceContext};
use crate::type_check::Locations;
use rustc_infer::infer::NllRegionVariableOrigin;
use rustc_middle::ty::TyCtxt;
use std::io::{self, Write};
// 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, tcx: TyCtxt<'tcx>, out: &mut dyn Write) -> io::Result<()> {
writeln!(out, "| Free Region Mapping")?;
for region in self.regions() {
if let NllRegionVariableOrigin::FreeRegion = self.definitions[region].origin {
let classification = self.universal_regions.region_classification(region).unwrap();
let outlived_by = self.universal_region_relations.regions_outlived_by(region);
writeln!(
out,
"| {r:rw$?} | {c:cw$?} | {ob:?}",
r = region,
rw = REGION_WIDTH,
c = classification,
cw = 8, // "External" at most
ob = outlived_by
)?;
}
}
writeln!(out, "|")?;
writeln!(out, "| Inferred Region Values")?;
for region in self.regions() {
writeln!(
out,
"| {r:rw$?} | {ui:4?} | {v}",
r = region,
rw = REGION_WIDTH,
ui = self.region_universe(region),
v = self.region_value_str(region),
)?;
}
writeln!(out, "|")?;
writeln!(out, "| Inference Constraints")?;
self.for_each_constraint(tcx, &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,
tcx: TyCtxt<'tcx>,
with_msg: &mut dyn FnMut(&str) -> io::Result<()>,
) -> io::Result<()> {
for region in self.definitions.indices() {
let value = self.liveness_constraints.pretty_print_live_points(region);
if value != "{}" {
with_msg(&format!("{region:?} live at {value}"))?;
}
}
let mut constraints: Vec<_> = self.constraints.outlives().iter().collect();
constraints.sort_by_key(|c| (c.sup, c.sub));
for constraint in &constraints {
let OutlivesConstraint { sup, sub, locations, category, span, .. } = constraint;
let (name, arg) = match locations {
Locations::All(span) => {
("All", tcx.sess.source_map().span_to_embeddable_string(*span))
}
Locations::Single(loc) => ("Single", format!("{loc:?}")),
};
with_msg(&format!("{sup:?}: {sub:?} due to {category:?} at {name}({arg}) ({span:?}"))?;
}
Ok(())
}
}
|