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[mir-opt] Introduce a new flag to enable experimental/unsound mir opts
1 parent 7467d17 commit eb3eb85

23 files changed

+287
-277
lines changed

‎compiler/rustc_mir/src/transform/copy_prop.rs

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -31,9 +31,11 @@ pub struct CopyPropagation;
3131

3232
impl<'tcx> MirPass<'tcx> for CopyPropagation {
3333
fn run_pass(&self, tcx: TyCtxt<'tcx>, _source: MirSource<'tcx>, body: &mut Body<'tcx>) {
34+
let opts = &tcx.sess.opts.debugging_opts;
3435
// We only run when the MIR optimization level is > 1.
3536
// This avoids a slow pass, and messing up debug info.
36-
if tcx.sess.opts.debugging_opts.mir_opt_level <= 1 {
37+
// FIXME(76740): This optimization is buggy and can cause unsoundness.
38+
if opts.mir_opt_level <= 1 || !opts.unsound_mir_opts {
3739
return;
3840
}
3941

‎compiler/rustc_mir/src/transform/simplify_try.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -612,7 +612,7 @@ impl<'a, 'tcx> SimplifyBranchSameOptimizationFinder<'a, 'tcx> {
612612
&& bb_l.terminator().kind == bb_r.terminator().kind;
613613
let statement_check = || {
614614
bb_l.statements.iter().zip(&bb_r.statements).try_fold(StatementEquality::TrivialEqual, |acc,(l,r)| {
615-
let stmt_equality = self.statement_equality(*adt_matched_on, &l, bb_l_idx, &r, bb_r_idx, self.tcx.sess.opts.debugging_opts.mir_opt_level);
615+
let stmt_equality = self.statement_equality(*adt_matched_on, &l, bb_l_idx, &r, bb_r_idx, self.tcx);
616616
if matches!(stmt_equality, StatementEquality::NotEqual) {
617617
// short circuit
618618
None
@@ -672,7 +672,7 @@ impl<'a, 'tcx> SimplifyBranchSameOptimizationFinder<'a, 'tcx> {
672672
x_bb_idx: BasicBlock,
673673
y: &Statement<'tcx>,
674674
y_bb_idx: BasicBlock,
675-
mir_opt_level: usize,
675+
tcx: TyCtxt<'tcx>,
676676
) -> StatementEquality {
677677
let helper = |rhs: &Rvalue<'tcx>,
678678
place: &Place<'tcx>,
@@ -693,7 +693,7 @@ impl<'a, 'tcx> SimplifyBranchSameOptimizationFinder<'a, 'tcx> {
693693
Rvalue::Use(operand) if operand.place() == Some(adt_matched_on) => {
694694
// FIXME(76803): This logic is currently broken because it does not take into
695695
// account the current discriminant value.
696-
if mir_opt_level > 2 {
696+
if tcx.sess.opts.debugging_opts.unsound_mir_opts {
697697
StatementEquality::ConsideredEqual(side_to_choose)
698698
} else {
699699
StatementEquality::NotEqual

‎compiler/rustc_session/src/options.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1115,6 +1115,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
11151115
`hir,typed` (HIR with types for each node),
11161116
`hir-tree` (dump the raw HIR),
11171117
`mir` (the MIR), or `mir-cfg` (graphviz formatted MIR)"),
1118+
unsound_mir_opts: bool = (false, parse_bool, [TRACKED],
1119+
"enable unsound and buggy MIR optimizations (default: no)"),
11181120
unstable_options: bool = (false, parse_bool, [UNTRACKED],
11191121
"adds unstable command line options to rustc interface (default: no)"),
11201122
use_ctors_section: Option<bool> = (None, parse_opt_bool, [TRACKED],

‎src/test/mir-opt/copy_propagation.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,4 @@
1+
// compile-flags: -Zunsound-mir-opts
12
// EMIT_MIR copy_propagation.test.CopyPropagation.diff
23

34
fn test(x: u32) -> u32 {

‎src/test/mir-opt/copy_propagation.test.CopyPropagation.diff

Lines changed: 9 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -2,19 +2,19 @@
22
+ // MIR for `test` after CopyPropagation
33

44
fn test(_1: u32) -> u32 {
5-
debug x => _1; // in scope 0 at $DIR/copy_propagation.rs:3:9: 3:10
6-
let mut _0: u32; // return place in scope 0 at $DIR/copy_propagation.rs:3:20: 3:23
7-
let _2: u32; // in scope 0 at $DIR/copy_propagation.rs:4:9: 4:10
5+
debug x => _1; // in scope 0 at $DIR/copy_propagation.rs:4:9: 4:10
6+
let mut _0: u32; // return place in scope 0 at $DIR/copy_propagation.rs:4:20: 4:23
7+
let _2: u32; // in scope 0 at $DIR/copy_propagation.rs:5:9: 5:10
88
scope 1 {
9-
debug y => _0; // in scope 1 at $DIR/copy_propagation.rs:4:9: 4:10
9+
debug y => _0; // in scope 1 at $DIR/copy_propagation.rs:5:9: 5:10
1010
}
1111

1212
bb0: {
13-
nop; // scope 0 at $DIR/copy_propagation.rs:4:9: 4:10
14-
_0 = _1; // scope 0 at $DIR/copy_propagation.rs:4:13: 4:14
15-
nop; // scope 1 at $DIR/copy_propagation.rs:5:5: 5:6
16-
nop; // scope 0 at $DIR/copy_propagation.rs:6:1: 6:2
17-
return; // scope 0 at $DIR/copy_propagation.rs:6:2: 6:2
13+
nop; // scope 0 at $DIR/copy_propagation.rs:5:9: 5:10
14+
_0 = _1; // scope 0 at $DIR/copy_propagation.rs:5:13: 5:14
15+
nop; // scope 1 at $DIR/copy_propagation.rs:6:5: 6:6
16+
nop; // scope 0 at $DIR/copy_propagation.rs:7:1: 7:2
17+
return; // scope 0 at $DIR/copy_propagation.rs:7:2: 7:2
1818
}
1919
}
2020

‎src/test/mir-opt/early_otherwise_branch_68867.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
// ignore-tidy-linelength
2-
// compile-flags: -Z mir-opt-level=3
2+
// compile-flags: -Z mir-opt-level=3 -Zunsound-mir-opts
33

44
// example from #68867
55
type CSSFloat = f32;

‎src/test/mir-opt/inline/inline-any-operand.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
// compile-flags: -Z span_free_formats
1+
// compile-flags: -Z span_free_formats -Zunsound-mir-opts
22

33
// Tests that MIR inliner works for any operand
44

‎src/test/mir-opt/inline/inline-closure-borrows-arg.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
// compile-flags: -Z span_free_formats
1+
// compile-flags: -Z span_free_formats -Zunsound-mir-opts
22

33
// Tests that MIR inliner can handle closure arguments,
44
// even when (#45894)

‎src/test/mir-opt/inline/inline-trait-method_2.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
// compile-flags: -Z span_free_formats -Z mir-opt-level=3
1+
// compile-flags: -Z span_free_formats -Z mir-opt-level=3 -Zunsound-mir-opts
22

33
// EMIT_MIR inline_trait_method_2.test2.Inline.after.mir
44
fn test2(x: &dyn X) -> bool {

‎src/test/mir-opt/issue-73223.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,5 @@
1+
// compile-flags: -Zunsound-mir-opts
2+
13
fn main() {
24
let split = match Some(1) {
35
Some(v) => v,

‎src/test/mir-opt/issue_73223.main.PreCodegen.32bit.diff

Lines changed: 16 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -2,9 +2,9 @@
22
+ // MIR for `main` after PreCodegen
33

44
fn main() -> () {
5-
let mut _0: (); // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
6-
let _1: i32; // in scope 0 at $DIR/issue-73223.rs:2:9: 2:14
7-
let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
5+
let mut _0: (); // return place in scope 0 at $DIR/issue-73223.rs:3:11: 3:11
6+
let _1: i32; // in scope 0 at $DIR/issue-73223.rs:4:9: 4:14
7+
let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:4:23: 4:30
88
let mut _4: (&i32, &i32); // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
99
let mut _5: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
1010
let mut _6: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
@@ -20,10 +20,10 @@
2020
let mut _16: std::fmt::ArgumentV1; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
2121
let mut _17: std::fmt::ArgumentV1; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
2222
scope 1 {
23-
debug split => _1; // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
24-
let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
23+
debug split => _1; // in scope 1 at $DIR/issue-73223.rs:4:9: 4:14
24+
let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:9:9: 9:14
2525
scope 3 {
26-
debug _prev => _3; // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
26+
debug _prev => _3; // in scope 3 at $DIR/issue-73223.rs:9:9: 9:14
2727
scope 4 {
2828
debug left_val => _13; // in scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
2929
debug right_val => _15; // in scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
@@ -55,21 +55,21 @@
5555
}
5656
}
5757
scope 2 {
58-
debug v => _1; // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
58+
debug v => _1; // in scope 2 at $DIR/issue-73223.rs:5:14: 5:15
5959
}
6060
scope 7 {
6161
}
6262
scope 9 {
6363
}
6464

6565
bb0: {
66-
StorageLive(_2); // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
67-
((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
68-
discriminant(_2) = 1; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
69-
_1 = ((_2 as Some).0: i32); // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
70-
StorageDead(_2); // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
71-
((_3 as Some).0: i32) = _1; // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
72-
discriminant(_3) = 1; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
66+
StorageLive(_2); // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
67+
((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
68+
discriminant(_2) = 1; // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
69+
_1 = ((_2 as Some).0: i32); // scope 0 at $DIR/issue-73223.rs:5:14: 5:15
70+
StorageDead(_2); // scope 0 at $DIR/issue-73223.rs:7:6: 7:7
71+
((_3 as Some).0: i32) = _1; // scope 1 at $DIR/issue-73223.rs:9:22: 9:27
72+
discriminant(_3) = 1; // scope 1 at $DIR/issue-73223.rs:9:17: 9:28
7373
(_4.0: &i32) = &_1; // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
7474
(_4.1: &i32) = const main::promoted[1]; // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
7575
// ty::Const
@@ -93,8 +93,8 @@
9393

9494
bb1: {
9595
StorageDead(_5); // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
96-
_0 = const (); // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
97-
return; // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
96+
_0 = const (); // scope 0 at $DIR/issue-73223.rs:3:11: 11:2
97+
return; // scope 0 at $DIR/issue-73223.rs:11:2: 11:2
9898
}
9999

100100
bb2: {

‎src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff

Lines changed: 16 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -2,9 +2,9 @@
22
+ // MIR for `main` after PreCodegen
33

44
fn main() -> () {
5-
let mut _0: (); // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
6-
let _1: i32; // in scope 0 at $DIR/issue-73223.rs:2:9: 2:14
7-
let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
5+
let mut _0: (); // return place in scope 0 at $DIR/issue-73223.rs:3:11: 3:11
6+
let _1: i32; // in scope 0 at $DIR/issue-73223.rs:4:9: 4:14
7+
let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:4:23: 4:30
88
let mut _4: (&i32, &i32); // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
99
let mut _5: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
1010
let mut _6: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
@@ -20,10 +20,10 @@
2020
let mut _16: std::fmt::ArgumentV1; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
2121
let mut _17: std::fmt::ArgumentV1; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
2222
scope 1 {
23-
debug split => _1; // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
24-
let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
23+
debug split => _1; // in scope 1 at $DIR/issue-73223.rs:4:9: 4:14
24+
let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:9:9: 9:14
2525
scope 3 {
26-
debug _prev => _3; // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
26+
debug _prev => _3; // in scope 3 at $DIR/issue-73223.rs:9:9: 9:14
2727
scope 4 {
2828
debug left_val => _13; // in scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
2929
debug right_val => _15; // in scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
@@ -55,21 +55,21 @@
5555
}
5656
}
5757
scope 2 {
58-
debug v => _1; // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
58+
debug v => _1; // in scope 2 at $DIR/issue-73223.rs:5:14: 5:15
5959
}
6060
scope 7 {
6161
}
6262
scope 9 {
6363
}
6464

6565
bb0: {
66-
StorageLive(_2); // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
67-
((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
68-
discriminant(_2) = 1; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
69-
_1 = ((_2 as Some).0: i32); // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
70-
StorageDead(_2); // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
71-
((_3 as Some).0: i32) = _1; // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
72-
discriminant(_3) = 1; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
66+
StorageLive(_2); // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
67+
((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
68+
discriminant(_2) = 1; // scope 0 at $DIR/issue-73223.rs:4:23: 4:30
69+
_1 = ((_2 as Some).0: i32); // scope 0 at $DIR/issue-73223.rs:5:14: 5:15
70+
StorageDead(_2); // scope 0 at $DIR/issue-73223.rs:7:6: 7:7
71+
((_3 as Some).0: i32) = _1; // scope 1 at $DIR/issue-73223.rs:9:22: 9:27
72+
discriminant(_3) = 1; // scope 1 at $DIR/issue-73223.rs:9:17: 9:28
7373
(_4.0: &i32) = &_1; // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
7474
(_4.1: &i32) = const main::promoted[1]; // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
7575
// ty::Const
@@ -93,8 +93,8 @@
9393

9494
bb1: {
9595
StorageDead(_5); // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
96-
_0 = const (); // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
97-
return; // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
96+
_0 = const (); // scope 0 at $DIR/issue-73223.rs:3:11: 11:2
97+
return; // scope 0 at $DIR/issue-73223.rs:11:2: 11:2
9898
}
9999

100100
bb2: {

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