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Rollup merge of rust-lang#76659 - simonvandel:76432, r=oli-obk
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SimplifyComparisonIntegral: fix miscompilation

Fixes rust-lang#76432
Only insert StorageDeads if we actually removed one.
Fixes an issue where we added StorageDead to a place with no StorageLive

r? @oli-obk
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@Dylan-DPC
Dylan-DPC authored Sep 19, 2020
2 parents aa81536 + e5447a2 commit 8549f2e
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Showing 3 changed files with 154 additions and 21 deletions.
43 changes: 22 additions & 21 deletions compiler/rustc_mir/src/transform/simplify_comparison_integral.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -61,26 +61,6 @@ impl<'tcx> MirPass<'tcx> for SimplifyComparisonIntegral {
_ => unreachable!(),
}

let terminator = bb.terminator_mut();

// add StorageDead for the place switched on at the top of each target
for bb_idx in new_targets.iter() {
storage_deads_to_insert.push((
*bb_idx,
Statement {
source_info: terminator.source_info,
kind: StatementKind::StorageDead(opt.to_switch_on.local),
},
));
}

terminator.kind = TerminatorKind::SwitchInt {
discr: Operand::Move(opt.to_switch_on),
switch_ty: opt.branch_value_ty,
values: vec![new_value].into(),
targets: new_targets,
};

// delete comparison statement if it the value being switched on was moved, which means it can not be user later on
if opt.can_remove_bin_op_stmt {
bb.statements[opt.bin_op_stmt_idx].make_nop();
Expand All @@ -106,14 +86,35 @@ impl<'tcx> MirPass<'tcx> for SimplifyComparisonIntegral {
}
}

let terminator = bb.terminator();

// remove StorageDead (if it exists) being used in the assign of the comparison
for (stmt_idx, stmt) in bb.statements.iter().enumerate() {
if !matches!(stmt.kind, StatementKind::StorageDead(local) if local == opt.to_switch_on.local)
{
continue;
}
storage_deads_to_remove.push((stmt_idx, opt.bb_idx))
storage_deads_to_remove.push((stmt_idx, opt.bb_idx));
// if we have StorageDeads to remove then make sure to insert them at the top of each target
for bb_idx in new_targets.iter() {
storage_deads_to_insert.push((
*bb_idx,
Statement {
source_info: terminator.source_info,
kind: StatementKind::StorageDead(opt.to_switch_on.local),
},
));
}
}

let terminator = bb.terminator_mut();

terminator.kind = TerminatorKind::SwitchInt {
discr: Operand::Move(opt.to_switch_on),
switch_ty: opt.branch_value_ty,
values: vec![new_value].into(),
targets: new_targets,
};
}

for (idx, bb_idx) in storage_deads_to_remove {
Expand Down
16 changes: 16 additions & 0 deletions src/test/mir-opt/issue_76432.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
// Check that we do not insert StorageDead at each target if StorageDead was never seen

// EMIT_MIR issue_76432.test.SimplifyComparisonIntegral.diff
use std::fmt::Debug;

fn test<T: Copy + Debug + PartialEq>(x: T) {
let v: &[T] = &[x, x, x];
match v {
[ref v1, ref v2, ref v3] => [v1 as *const _, v2 as *const _, v3 as *const _],
_ => unreachable!(),
};
}

fn main() {
test(0u32);
}
116 changes: 116 additions & 0 deletions src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff
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Original file line number Diff line number Diff line change
@@ -0,0 +1,116 @@
- // MIR for `test` before SimplifyComparisonIntegral
+ // MIR for `test` after SimplifyComparisonIntegral

fn test(_1: T) -> () {
debug x => _1; // in scope 0 at $DIR/issue_76432.rs:6:38: 6:39
let mut _0: (); // return place in scope 0 at $DIR/issue_76432.rs:6:44: 6:44
let _2: &[T]; // in scope 0 at $DIR/issue_76432.rs:7:9: 7:10
let mut _3: &[T; 3]; // in scope 0 at $DIR/issue_76432.rs:7:19: 7:29
let _4: &[T; 3]; // in scope 0 at $DIR/issue_76432.rs:7:19: 7:29
let _5: [T; 3]; // in scope 0 at $DIR/issue_76432.rs:7:20: 7:29
let mut _6: T; // in scope 0 at $DIR/issue_76432.rs:7:21: 7:22
let mut _7: T; // in scope 0 at $DIR/issue_76432.rs:7:24: 7:25
let mut _8: T; // in scope 0 at $DIR/issue_76432.rs:7:27: 7:28
let _9: [*const T; 3]; // in scope 0 at $DIR/issue_76432.rs:8:5: 11:6
let mut _10: usize; // in scope 0 at $DIR/issue_76432.rs:9:9: 9:33
let mut _11: usize; // in scope 0 at $DIR/issue_76432.rs:9:9: 9:33
let mut _12: bool; // in scope 0 at $DIR/issue_76432.rs:9:9: 9:33
let mut _16: *const T; // in scope 0 at $DIR/issue_76432.rs:9:38: 9:52
let mut _17: *const T; // in scope 0 at $DIR/issue_76432.rs:9:38: 9:52
let mut _18: *const T; // in scope 0 at $DIR/issue_76432.rs:9:54: 9:68
let mut _19: *const T; // in scope 0 at $DIR/issue_76432.rs:9:54: 9:68
let mut _20: *const T; // in scope 0 at $DIR/issue_76432.rs:9:70: 9:84
let mut _21: *const T; // in scope 0 at $DIR/issue_76432.rs:9:70: 9:84
let mut _22: !; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
scope 1 {
debug v => _2; // in scope 1 at $DIR/issue_76432.rs:7:9: 7:10
let _13: &T; // in scope 1 at $DIR/issue_76432.rs:9:10: 9:16
let _14: &T; // in scope 1 at $DIR/issue_76432.rs:9:18: 9:24
let _15: &T; // in scope 1 at $DIR/issue_76432.rs:9:26: 9:32
scope 2 {
debug v1 => _13; // in scope 2 at $DIR/issue_76432.rs:9:10: 9:16
debug v2 => _14; // in scope 2 at $DIR/issue_76432.rs:9:18: 9:24
debug v3 => _15; // in scope 2 at $DIR/issue_76432.rs:9:26: 9:32
}
}

bb0: {
StorageLive(_2); // scope 0 at $DIR/issue_76432.rs:7:9: 7:10
StorageLive(_3); // scope 0 at $DIR/issue_76432.rs:7:19: 7:29
StorageLive(_4); // scope 0 at $DIR/issue_76432.rs:7:19: 7:29
StorageLive(_5); // scope 0 at $DIR/issue_76432.rs:7:20: 7:29
StorageLive(_6); // scope 0 at $DIR/issue_76432.rs:7:21: 7:22
_6 = _1; // scope 0 at $DIR/issue_76432.rs:7:21: 7:22
StorageLive(_7); // scope 0 at $DIR/issue_76432.rs:7:24: 7:25
_7 = _1; // scope 0 at $DIR/issue_76432.rs:7:24: 7:25
StorageLive(_8); // scope 0 at $DIR/issue_76432.rs:7:27: 7:28
_8 = _1; // scope 0 at $DIR/issue_76432.rs:7:27: 7:28
_5 = [move _6, move _7, move _8]; // scope 0 at $DIR/issue_76432.rs:7:20: 7:29
StorageDead(_8); // scope 0 at $DIR/issue_76432.rs:7:28: 7:29
StorageDead(_7); // scope 0 at $DIR/issue_76432.rs:7:28: 7:29
StorageDead(_6); // scope 0 at $DIR/issue_76432.rs:7:28: 7:29
_4 = &_5; // scope 0 at $DIR/issue_76432.rs:7:19: 7:29
_3 = _4; // scope 0 at $DIR/issue_76432.rs:7:19: 7:29
_2 = move _3 as &[T] (Pointer(Unsize)); // scope 0 at $DIR/issue_76432.rs:7:19: 7:29
StorageDead(_3); // scope 0 at $DIR/issue_76432.rs:7:28: 7:29
StorageDead(_4); // scope 0 at $DIR/issue_76432.rs:7:29: 7:30
StorageLive(_9); // scope 1 at $DIR/issue_76432.rs:8:5: 11:6
_10 = Len((*_2)); // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
_11 = const 3_usize; // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
- _12 = Eq(move _10, const 3_usize); // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
- switchInt(move _12) -> [false: bb1, otherwise: bb2]; // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
+ nop; // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
+ switchInt(move _10) -> [3_usize: bb2, otherwise: bb1]; // scope 1 at $DIR/issue_76432.rs:9:9: 9:33
}

bb1: {
StorageLive(_22); // scope 1 at $SRC_DIR/std/src/macros.rs:LL:COL
begin_panic::<&str>(const "internal error: entered unreachable code"); // scope 1 at $SRC_DIR/std/src/macros.rs:LL:COL
// mir::Constant
// + span: $SRC_DIR/std/src/macros.rs:LL:COL
// + literal: Const { ty: fn(&str) -> ! {std::rt::begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
// ty::Const
// + ty: &str
// + val: Value(Slice { data: Allocation { bytes: [105, 110, 116, 101, 114, 110, 97, 108, 32, 101, 114, 114, 111, 114, 58, 32, 101, 110, 116, 101, 114, 101, 100, 32, 117, 110, 114, 101, 97, 99, 104, 97, 98, 108, 101, 32, 99, 111, 100, 101], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1099511627775], len: Size { raw: 40 } }, size: Size { raw: 40 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 40 })
// mir::Constant
// + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [105, 110, 116, 101, 114, 110, 97, 108, 32, 101, 114, 114, 111, 114, 58, 32, 101, 110, 116, 101, 114, 101, 100, 32, 117, 110, 114, 101, 97, 99, 104, 97, 98, 108, 101, 32, 99, 111, 100, 101], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1099511627775], len: Size { raw: 40 } }, size: Size { raw: 40 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 40 }) }
}

bb2: {
StorageLive(_13); // scope 1 at $DIR/issue_76432.rs:9:10: 9:16
_13 = &(*_2)[0 of 3]; // scope 1 at $DIR/issue_76432.rs:9:10: 9:16
StorageLive(_14); // scope 1 at $DIR/issue_76432.rs:9:18: 9:24
_14 = &(*_2)[1 of 3]; // scope 1 at $DIR/issue_76432.rs:9:18: 9:24
StorageLive(_15); // scope 1 at $DIR/issue_76432.rs:9:26: 9:32
_15 = &(*_2)[2 of 3]; // scope 1 at $DIR/issue_76432.rs:9:26: 9:32
StorageLive(_16); // scope 2 at $DIR/issue_76432.rs:9:38: 9:52
StorageLive(_17); // scope 2 at $DIR/issue_76432.rs:9:38: 9:52
_17 = &raw const (*_13); // scope 2 at $DIR/issue_76432.rs:9:38: 9:40
_16 = _17; // scope 2 at $DIR/issue_76432.rs:9:38: 9:52
StorageLive(_18); // scope 2 at $DIR/issue_76432.rs:9:54: 9:68
StorageLive(_19); // scope 2 at $DIR/issue_76432.rs:9:54: 9:68
_19 = &raw const (*_14); // scope 2 at $DIR/issue_76432.rs:9:54: 9:56
_18 = _19; // scope 2 at $DIR/issue_76432.rs:9:54: 9:68
StorageLive(_20); // scope 2 at $DIR/issue_76432.rs:9:70: 9:84
StorageLive(_21); // scope 2 at $DIR/issue_76432.rs:9:70: 9:84
_21 = &raw const (*_15); // scope 2 at $DIR/issue_76432.rs:9:70: 9:72
_20 = _21; // scope 2 at $DIR/issue_76432.rs:9:70: 9:84
_9 = [move _16, move _18, move _20]; // scope 2 at $DIR/issue_76432.rs:9:37: 9:85
StorageDead(_21); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_20); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_19); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_18); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_17); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_16); // scope 2 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_15); // scope 1 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_14); // scope 1 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_13); // scope 1 at $DIR/issue_76432.rs:9:84: 9:85
StorageDead(_9); // scope 1 at $DIR/issue_76432.rs:11:6: 11:7
_0 = const (); // scope 0 at $DIR/issue_76432.rs:6:44: 12:2
StorageDead(_5); // scope 0 at $DIR/issue_76432.rs:12:1: 12:2
StorageDead(_2); // scope 0 at $DIR/issue_76432.rs:12:1: 12:2
return; // scope 0 at $DIR/issue_76432.rs:12:2: 12:2
}
}

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