This repository has been archived by the owner on Dec 29, 2022. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 258
/
deaggregator.rs
130 lines (120 loc) · 5.46 KB
/
deaggregator.rs
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
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
// Copyright 2016 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.
use rustc::ty::TyCtxt;
use rustc::mir::*;
use rustc::mir::transform::{MirPass, MirSource};
use rustc_data_structures::indexed_vec::Idx;
pub struct Deaggregator;
impl MirPass for Deaggregator {
fn run_pass<'a, 'tcx>(&self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
source: MirSource,
mir: &mut Mir<'tcx>) {
let node_id = source.item_id();
let node_path = tcx.item_path_str(tcx.hir.local_def_id(node_id));
debug!("running on: {:?}", node_path);
// we only run when mir_opt_level > 2
if tcx.sess.opts.debugging_opts.mir_opt_level <= 2 {
return;
}
// Do not trigger on constants. Could be revised in future
if let MirSource::Fn(_) = source {} else { return; }
// In fact, we might not want to trigger in other cases.
// Ex: when we could use SROA. See issue #35259
for bb in mir.basic_blocks_mut() {
let mut curr: usize = 0;
while let Some(idx) = get_aggregate_statement_index(curr, &bb.statements) {
// do the replacement
debug!("removing statement {:?}", idx);
let src_info = bb.statements[idx].source_info;
let suffix_stmts = bb.statements.split_off(idx+1);
let orig_stmt = bb.statements.pop().unwrap();
let (lhs, rhs) = match orig_stmt.kind {
StatementKind::Assign(ref lhs, ref rhs) => (lhs, rhs),
_ => span_bug!(src_info.span, "expected assign, not {:?}", orig_stmt),
};
let (agg_kind, operands) = match rhs {
&Rvalue::Aggregate(ref agg_kind, ref operands) => (agg_kind, operands),
_ => span_bug!(src_info.span, "expected aggregate, not {:?}", rhs),
};
let (adt_def, variant, substs) = match **agg_kind {
AggregateKind::Adt(adt_def, variant, substs, None)
=> (adt_def, variant, substs),
_ => span_bug!(src_info.span, "expected struct, not {:?}", rhs),
};
let n = bb.statements.len();
bb.statements.reserve(n + operands.len() + suffix_stmts.len());
for (i, op) in operands.iter().enumerate() {
let ref variant_def = adt_def.variants[variant];
let ty = variant_def.fields[i].ty(tcx, substs);
let rhs = Rvalue::Use(op.clone());
let lhs_cast = if adt_def.variants.len() > 1 {
Lvalue::Projection(Box::new(LvalueProjection {
base: lhs.clone(),
elem: ProjectionElem::Downcast(adt_def, variant),
}))
} else {
lhs.clone()
};
let lhs_proj = Lvalue::Projection(Box::new(LvalueProjection {
base: lhs_cast,
elem: ProjectionElem::Field(Field::new(i), ty),
}));
let new_statement = Statement {
source_info: src_info,
kind: StatementKind::Assign(lhs_proj, rhs),
};
debug!("inserting: {:?} @ {:?}", new_statement, idx + i);
bb.statements.push(new_statement);
}
// if the aggregate was an enum, we need to set the discriminant
if adt_def.variants.len() > 1 {
let set_discriminant = Statement {
kind: StatementKind::SetDiscriminant {
lvalue: lhs.clone(),
variant_index: variant,
},
source_info: src_info,
};
bb.statements.push(set_discriminant);
};
curr = bb.statements.len();
bb.statements.extend(suffix_stmts);
}
}
}
}
fn get_aggregate_statement_index<'a, 'tcx, 'b>(start: usize,
statements: &Vec<Statement<'tcx>>)
-> Option<usize> {
for i in start..statements.len() {
let ref statement = statements[i];
let rhs = match statement.kind {
StatementKind::Assign(_, ref rhs) => rhs,
_ => continue,
};
let (kind, operands) = match rhs {
&Rvalue::Aggregate(ref kind, ref operands) => (kind, operands),
_ => continue,
};
let (adt_def, variant) = match **kind {
AggregateKind::Adt(adt_def, variant, _, None) => (adt_def, variant),
_ => continue,
};
if operands.len() == 0 {
// don't deaggregate ()
continue;
}
debug!("getting variant {:?}", variant);
debug!("for adt_def {:?}", adt_def);
return Some(i);
};
None
}