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Fix uninhabited enum branching pass #85603

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Merged
merged 2 commits into from
Jun 25, 2021
Merged

Fix uninhabited enum branching pass #85603

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5ee6897
Test for unihnabitded_enum_branching pass using reference to fields
ogoffart May 23, 2021
5bece28
unhinabited_enum_branching: Fix the pass when the enum is taken indir…
ogoffart May 23, 2021
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12 changes: 5 additions & 7 deletions compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ fn get_discriminant_local(terminator: &TerminatorKind<'_>) -> Option<Local> {
/// discriminant is read from. Otherwise, returns None.
fn get_switched_on_type<'tcx>(
block_data: &BasicBlockData<'tcx>,
tcx: TyCtxt<'tcx>,
body: &Body<'tcx>,
) -> Option<Ty<'tcx>> {
let terminator = block_data.terminator();
Expand All @@ -36,12 +37,9 @@ fn get_switched_on_type<'tcx>(
if let Some(StatementKind::Assign(box (l, Rvalue::Discriminant(place)))) = stmt_before_term
{
if l.as_local() == Some(local) {
if let Some(r_local) = place.as_local() {
let ty = body.local_decls[r_local].ty;

if ty.is_enum() {
return Some(ty);
}
let ty = place.ty(body, tcx).ty;
if ty.is_enum() {
return Some(ty);
}
}
}
Expand Down Expand Up @@ -86,7 +84,7 @@ impl<'tcx> MirPass<'tcx> for UninhabitedEnumBranching {
trace!("processing block {:?}", bb);

let discriminant_ty =
if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], body) {
if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], tcx, body) {
ty
} else {
continue;
Expand Down
106 changes: 106 additions & 0 deletions ...t/uninhabited_enum_branching2.main.SimplifyCfg-after-uninhabited-enum-branching.after.mir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,106 @@
// MIR for `main` after SimplifyCfg-after-uninhabited-enum-branching

fn main() -> () {
let mut _0: (); // return place in scope 0 at $DIR/uninhabited_enum_branching2.rs:18:11: 18:11
let _1: Plop; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:19:9: 19:13
let mut _2: Test1; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:19:38: 19:46
let _3: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
let mut _4: &Test1; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
let mut _5: isize; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
let _6: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:23:24: 23:34
let _7: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
let _8: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
let _9: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
let mut _10: isize; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
let _11: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:30:24: 30:34
let _12: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
let _13: &str; // in scope 0 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
scope 1 {
debug plop => _1; // in scope 1 at $DIR/uninhabited_enum_branching2.rs:19:9: 19:13
}

bb0: {
StorageLive(_1); // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:9: 19:13
StorageLive(_2); // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:38: 19:46
discriminant(_2) = 2; // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:38: 19:46
(_1.0: u32) = const 51_u32; // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:16: 19:48
(_1.1: Test1) = move _2; // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:16: 19:48
StorageDead(_2); // scope 0 at $DIR/uninhabited_enum_branching2.rs:19:47: 19:48
StorageLive(_3); // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
StorageLive(_4); // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
_4 = &(_1.1: Test1); // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
_5 = discriminant((*_4)); // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
switchInt(move _5) -> [2_isize: bb2, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
}

bb1: {
StorageLive(_8); // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
_8 = const "D"; // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
// ty::Const
// + ty: &str
// + val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 })
// mir::Constant
// + span: $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
_3 = &(*_8); // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
StorageDead(_8); // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:23: 25:24
goto -> bb3; // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
}

bb2: {
StorageLive(_7); // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
_7 = const "C"; // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
// ty::Const
// + ty: &str
// + val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 })
// mir::Constant
// + span: $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
_3 = &(*_7); // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
StorageDead(_7); // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:23: 24:24
goto -> bb3; // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
}

bb3: {
StorageDead(_4); // scope 1 at $DIR/uninhabited_enum_branching2.rs:26:6: 26:7
StorageDead(_3); // scope 1 at $DIR/uninhabited_enum_branching2.rs:26:6: 26:7
StorageLive(_9); // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
_10 = discriminant((_1.1: Test1)); // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
switchInt(move _10) -> [2_isize: bb5, otherwise: bb4]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
}

bb4: {
StorageLive(_13); // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
_13 = const "D"; // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
// ty::Const
// + ty: &str
// + val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 })
// mir::Constant
// + span: $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
_9 = &(*_13); // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
StorageDead(_13); // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:23: 32:24
goto -> bb6; // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
}

bb5: {
StorageLive(_12); // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
_12 = const "C"; // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
// ty::Const
// + ty: &str
// + val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 })
// mir::Constant
// + span: $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
_9 = &(*_12); // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
StorageDead(_12); // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:23: 31:24
goto -> bb6; // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
}

bb6: {
StorageDead(_9); // scope 1 at $DIR/uninhabited_enum_branching2.rs:33:6: 33:7
_0 = const (); // scope 0 at $DIR/uninhabited_enum_branching2.rs:18:11: 34:2
StorageDead(_1); // scope 0 at $DIR/uninhabited_enum_branching2.rs:34:1: 34:2
return; // scope 0 at $DIR/uninhabited_enum_branching2.rs:34:2: 34:2
}
}
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