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Revert "Simplify unscheduling of drops after moves"

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This reverts commit b766abc88f78f36193ddefb1079dbc832346b358.
This commit is contained in:
Felix S. Klock II 2021-01-21 22:44:02 -05:00
parent bed69c6134
commit dac354fc32
5 changed files with 80 additions and 31 deletions
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38
compiler/rustc_mir_build/src/build/scope.rs
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@ -83,7 +83,7 @@ that contains only loops and breakable blocks. It tracks where a `break`,
use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder, CFG};
use crate::thir::{Expr, ExprRef, LintLevel};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::fx::FxHashMap;
use rustc_index::vec::IndexVec;
use rustc_middle::middle::region;
use rustc_middle::mir::*;
@ -120,6 +120,8 @@ struct Scope {
/// end of the vector (top of the stack) first.
drops: Vec<DropData>,
moved_locals: Vec<Local>,
/// The drop index that will drop everything in and below this scope on an
/// unwind path.
cached_unwind_block: Option<DropIdx>,
@ -403,6 +405,7 @@ impl<'tcx> Scopes<'tcx> {
region_scope: region_scope.0,
region_scope_span: region_scope.1.span,
drops: vec![],
moved_locals: vec![],
cached_unwind_block: None,
cached_generator_drop_block: None,
});
@ -890,19 +893,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
assert_eq!(scope.region_scope, local_scope, "local scope is not the topmost scope!",);
// look for moves of a local variable, like `MOVE(_X)`
let locals_moved = operands
.iter()
.filter_map(|operand| match operand {
Operand::Copy(_) | Operand::Constant(_) => None,
Operand::Move(place) => place.as_local(),
})
.collect::<FxHashSet<_>>();
let locals_moved = operands.iter().flat_map(|operand| match operand {
Operand::Copy(_) | Operand::Constant(_) => None,
Operand::Move(place) => place.as_local(),
});
// Remove the drops for the moved operands.
scope
.drops
.retain(|drop| drop.kind == DropKind::Storage || !locals_moved.contains(&drop.local));
scope.invalidate_cache();
for local in locals_moved {
// check if we have a Drop for this operand and -- if so
// -- add it to the list of moved operands. Note that this
// local might not have been an operand created for this
// call, it could come from other places too.
if scope.drops.iter().any(|drop| drop.local == local && drop.kind == DropKind::Value) {
scope.moved_locals.push(local);
}
}
}
// Other
@ -1147,6 +1151,14 @@ fn build_scope_drops<'tcx>(
debug_assert_eq!(unwind_drops.drops[unwind_to].0.kind, drop_data.kind);
unwind_to = unwind_drops.drops[unwind_to].1;
// If the operand has been moved, and we are not on an unwind
// path, then don't generate the drop. (We only take this into
// account for non-unwind paths so as not to disturb the
// caching mechanism.)
if scope.moved_locals.iter().any(|&o| o == local) {
continue;
}
unwind_drops.add_entry(block, unwind_to);
let next = cfg.start_new_block();

10
src/test/mir-opt/box_expr.main.ElaborateDrops.before.mir
View File

@ -14,7 +14,7 @@ fn main() -> () {
StorageLive(_1); // scope 0 at $DIR/box_expr.rs:7:9: 7:10
StorageLive(_2); // scope 0 at $DIR/box_expr.rs:7:13: 7:25
_2 = Box(S); // scope 0 at $DIR/box_expr.rs:7:13: 7:25
(*_2) = S::new() -> [return: bb1, unwind: bb6]; // scope 0 at $DIR/box_expr.rs:7:17: 7:25
(*_2) = S::new() -> [return: bb1, unwind: bb7]; // scope 0 at $DIR/box_expr.rs:7:17: 7:25
// mir::Constant
// + span: $DIR/box_expr.rs:7:17: 7:23
// + literal: Const { ty: fn() -> S {S::new}, val: Value(Scalar(<ZST>)) }
@ -49,14 +49,18 @@ fn main() -> () {
}
bb5 (cleanup): {
drop(_1) -> bb7; // scope 0 at $DIR/box_expr.rs:9:1: 9:2
drop(_4) -> bb6; // scope 1 at $DIR/box_expr.rs:8:11: 8:12
}
bb6 (cleanup): {
drop(_2) -> bb7; // scope 0 at $DIR/box_expr.rs:7:24: 7:25
drop(_1) -> bb8; // scope 0 at $DIR/box_expr.rs:9:1: 9:2
}
bb7 (cleanup): {
drop(_2) -> bb8; // scope 0 at $DIR/box_expr.rs:7:24: 7:25
}
bb8 (cleanup): {
resume; // scope 0 at $DIR/box_expr.rs:6:1: 9:2
}
}

27
src/test/mir-opt/issue_41110.main.ElaborateDrops.after.mir
View File

@ -6,18 +6,21 @@ fn main() -> () {
let mut _2: S; // in scope 0 at $DIR/issue-41110.rs:8:13: 8:14
let mut _3: S; // in scope 0 at $DIR/issue-41110.rs:8:21: 8:27
let mut _4: S; // in scope 0 at $DIR/issue-41110.rs:8:21: 8:22
let mut _5: bool; // in scope 0 at $DIR/issue-41110.rs:8:27: 8:28
scope 1 {
debug x => _1; // in scope 1 at $DIR/issue-41110.rs:8:9: 8:10
}
bb0: {
_5 = const false; // scope 0 at $DIR/issue-41110.rs:8:9: 8:10
StorageLive(_1); // scope 0 at $DIR/issue-41110.rs:8:9: 8:10
StorageLive(_2); // scope 0 at $DIR/issue-41110.rs:8:13: 8:14
_5 = const true; // scope 0 at $DIR/issue-41110.rs:8:13: 8:14
_2 = S; // scope 0 at $DIR/issue-41110.rs:8:13: 8:14
StorageLive(_3); // scope 0 at $DIR/issue-41110.rs:8:21: 8:27
StorageLive(_4); // scope 0 at $DIR/issue-41110.rs:8:21: 8:22
_4 = S; // scope 0 at $DIR/issue-41110.rs:8:21: 8:22
_3 = S::id(move _4) -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/issue-41110.rs:8:21: 8:27
_3 = S::id(move _4) -> [return: bb1, unwind: bb4]; // scope 0 at $DIR/issue-41110.rs:8:21: 8:27
// mir::Constant
// + span: $DIR/issue-41110.rs:8:23: 8:25
// + literal: Const { ty: fn(S) -> S {S::id}, val: Value(Scalar(<ZST>)) }
@ -25,7 +28,8 @@ fn main() -> () {
bb1: {
StorageDead(_4); // scope 0 at $DIR/issue-41110.rs:8:26: 8:27
_1 = S::other(move _2, move _3) -> bb2; // scope 0 at $DIR/issue-41110.rs:8:13: 8:28
_5 = const false; // scope 0 at $DIR/issue-41110.rs:8:13: 8:28
_1 = S::other(move _2, move _3) -> [return: bb2, unwind: bb3]; // scope 0 at $DIR/issue-41110.rs:8:13: 8:28
// mir::Constant
// + span: $DIR/issue-41110.rs:8:15: 8:20
// + literal: Const { ty: fn(S, S) {S::other}, val: Value(Scalar(<ZST>)) }
@ -33,6 +37,7 @@ fn main() -> () {
bb2: {
StorageDead(_3); // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
_5 = const false; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
StorageDead(_2); // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
_0 = const (); // scope 0 at $DIR/issue-41110.rs:7:11: 9:2
StorageDead(_1); // scope 0 at $DIR/issue-41110.rs:9:1: 9:2
@ -40,10 +45,26 @@ fn main() -> () {
}
bb3 (cleanup): {
drop(_2) -> bb4; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
goto -> bb5; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
}
bb4 (cleanup): {
goto -> bb5; // scope 0 at $DIR/issue-41110.rs:8:26: 8:27
}
bb5 (cleanup): {
goto -> bb8; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
}
bb6 (cleanup): {
resume; // scope 0 at $DIR/issue-41110.rs:7:1: 9:2
}
bb7 (cleanup): {
drop(_2) -> bb6; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
}
bb8 (cleanup): {
switchInt(_5) -> [false: bb6, otherwise: bb7]; // scope 0 at $DIR/issue-41110.rs:8:27: 8:28
}
}

26
src/test/mir-opt/issue_41110.test.ElaborateDrops.after.mir
View File

@ -37,7 +37,7 @@ fn test() -> () {
StorageLive(_5); // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
_6 = const false; // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
_5 = move _1; // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
goto -> bb11; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
goto -> bb12; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
}
bb2: {
@ -47,7 +47,7 @@ fn test() -> () {
bb3: {
StorageDead(_5); // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
_0 = const (); // scope 0 at $DIR/issue-41110.rs:14:15: 19:2
drop(_2) -> [return: bb4, unwind: bb8]; // scope 1 at $DIR/issue-41110.rs:19:1: 19:2
drop(_2) -> [return: bb4, unwind: bb9]; // scope 1 at $DIR/issue-41110.rs:19:1: 19:2
}
bb4: {
@ -62,36 +62,40 @@ fn test() -> () {
}
bb6 (cleanup): {
goto -> bb7; // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
goto -> bb8; // scope 2 at $DIR/issue-41110.rs:18:9: 18:10
}
bb7 (cleanup): {
goto -> bb8; // scope 1 at $DIR/issue-41110.rs:19:1: 19:2
goto -> bb8; // scope 2 at $DIR/issue-41110.rs:17:11: 17:12
}
bb8 (cleanup): {
goto -> bb13; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
goto -> bb9; // scope 1 at $DIR/issue-41110.rs:19:1: 19:2
}
bb9 (cleanup): {
resume; // scope 0 at $DIR/issue-41110.rs:14:1: 19:2
goto -> bb14; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
}
bb10 (cleanup): {
resume; // scope 0 at $DIR/issue-41110.rs:14:1: 19:2
}
bb11 (cleanup): {
_2 = move _5; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
goto -> bb6; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
}
bb11: {
bb12: {
_2 = move _5; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
goto -> bb2; // scope 2 at $DIR/issue-41110.rs:18:5: 18:6
}
bb12 (cleanup): {
drop(_1) -> bb9; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
bb13 (cleanup): {
drop(_1) -> bb10; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
}
bb13 (cleanup): {
switchInt(_6) -> [false: bb9, otherwise: bb12]; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
bb14 (cleanup): {
switchInt(_6) -> [false: bb10, otherwise: bb13]; // scope 0 at $DIR/issue-41110.rs:19:1: 19:2
}
}

10
src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
View File

@ -28,7 +28,7 @@ fn main() -> () {
bb1: {
StorageDead(_3); // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:33: 9:34
_1 = std::mem::drop::<String>(move _2) -> bb2; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:5: 9:35
_1 = std::mem::drop::<String>(move _2) -> [return: bb2, unwind: bb3]; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:5: 9:35
// mir::Constant
// + span: $DIR/no-spurious-drop-after-call.rs:9:5: 9:19
// + literal: Const { ty: fn(std::string::String) {std::mem::drop::<std::string::String>}, val: Value(Scalar(<ZST>)) }
@ -41,4 +41,12 @@ fn main() -> () {
_0 = const (); // scope 0 at $DIR/no-spurious-drop-after-call.rs:8:11: 10:2
return; // scope 0 at $DIR/no-spurious-drop-after-call.rs:10:2: 10:2
}
bb3 (cleanup): {
drop(_2) -> bb4; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:34: 9:35
}
bb4 (cleanup): {
resume; // scope 0 at $DIR/no-spurious-drop-after-call.rs:8:1: 10:2
}
}