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Auto merge of rust-lang#124156 - DianQK:disable-match_branches, r=Ral…
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…fJung

Disable SimplifyToExp in MatchBranchSimplification

Due to the miscompilation mentioned in rust-lang#124150, We need to disable MatchBranchSimplification temporarily.

To fully resolve this issue, my plan is:
1. Disable SimplifyToExp in MatchBranchSimplification (this PR).
2. Remove all potentially unclear transforms in rust-lang#124122.
3. Gradually add back the removed transforms (possibly multiple PRs).

r? `@Nilstrieb` or `@oli-obk`
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@bors
bors committed Apr 20, 2024
2 parents f1bff1f + b52be28 commit a61b14d
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Showing 9 changed files with 160 additions and 202 deletions.
5 changes: 4 additions & 1 deletion compiler/rustc_mir_transform/src/match_branches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,10 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
should_cleanup = true;
continue;
}
if SimplifyToExp::default().simplify(tcx, body, bb_idx, param_env).is_some() {
// unsound: https://github.com/rust-lang/rust/issues/124150
if tcx.sess.opts.unstable_opts.unsound_mir_opts
&& SimplifyToExp::default().simplify(tcx, body, bb_idx, param_env).is_some()
{
should_cleanup = true;
continue;
}
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61 changes: 28 additions & 33 deletions tests/mir-opt/matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -5,42 +5,37 @@
debug i => _1;
let mut _0: u128;
let mut _2: i128;
+ let mut _3: i128;

bb0: {
_2 = discriminant(_1);
- switchInt(move _2) -> [1: bb3, 2: bb4, 3: bb5, 340282366920938463463374607431768211455: bb2, otherwise: bb1];
- }
-
- bb1: {
- unreachable;
- }
-
- bb2: {
- _0 = const core::num::<impl u128>::MAX;
- goto -> bb6;
- }
-
- bb3: {
- _0 = const 1_u128;
- goto -> bb6;
- }
-
- bb4: {
- _0 = const 2_u128;
- goto -> bb6;
- }
-
- bb5: {
- _0 = const 3_u128;
- goto -> bb6;
- }
-
- bb6: {
+ StorageLive(_3);
+ _3 = move _2;
+ _0 = _3 as u128 (IntToInt);
+ StorageDead(_3);
switchInt(move _2) -> [1: bb3, 2: bb4, 3: bb5, 340282366920938463463374607431768211455: bb2, otherwise: bb1];
}

bb1: {
unreachable;
}

bb2: {
_0 = const core::num::<impl u128>::MAX;
goto -> bb6;
}

bb3: {
_0 = const 1_u128;
goto -> bb6;
}

bb4: {
_0 = const 2_u128;
goto -> bb6;
}

bb5: {
_0 = const 3_u128;
goto -> bb6;
}

bb6: {
return;
}
}
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51 changes: 23 additions & 28 deletions tests/mir-opt/matches_reduce_branches.match_i16_i8.MatchBranchSimplification.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -5,37 +5,32 @@
debug i => _1;
let mut _0: i8;
let mut _2: i16;
+ let mut _3: i16;

bb0: {
_2 = discriminant(_1);
- switchInt(move _2) -> [65535: bb3, 2: bb4, 65533: bb2, otherwise: bb1];
- }
-
- bb1: {
- unreachable;
- }
-
- bb2: {
- _0 = const -3_i8;
- goto -> bb5;
- }
-
- bb3: {
- _0 = const -1_i8;
- goto -> bb5;
- }
-
- bb4: {
- _0 = const 2_i8;
- goto -> bb5;
- }
-
- bb5: {
+ StorageLive(_3);
+ _3 = move _2;
+ _0 = _3 as i8 (IntToInt);
+ StorageDead(_3);
switchInt(move _2) -> [65535: bb3, 2: bb4, 65533: bb2, otherwise: bb1];
}

bb1: {
unreachable;
}

bb2: {
_0 = const -3_i8;
goto -> bb5;
}

bb3: {
_0 = const -1_i8;
goto -> bb5;
}

bb4: {
_0 = const 2_i8;
goto -> bb5;
}

bb5: {
return;
}
}
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51 changes: 23 additions & 28 deletions tests/mir-opt/matches_reduce_branches.match_i8_i16.MatchBranchSimplification.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -5,37 +5,32 @@
debug i => _1;
let mut _0: i16;
let mut _2: i8;
+ let mut _3: i8;

bb0: {
_2 = discriminant(_1);
- switchInt(move _2) -> [255: bb3, 2: bb4, 253: bb2, otherwise: bb1];
- }
-
- bb1: {
- unreachable;
- }
-
- bb2: {
- _0 = const -3_i16;
- goto -> bb5;
- }
-
- bb3: {
- _0 = const -1_i16;
- goto -> bb5;
- }
-
- bb4: {
- _0 = const 2_i16;
- goto -> bb5;
- }
-
- bb5: {
+ StorageLive(_3);
+ _3 = move _2;
+ _0 = _3 as i16 (IntToInt);
+ StorageDead(_3);
switchInt(move _2) -> [255: bb3, 2: bb4, 253: bb2, otherwise: bb1];
}

bb1: {
unreachable;
}

bb2: {
_0 = const -3_i16;
goto -> bb5;
}

bb3: {
_0 = const -1_i16;
goto -> bb5;
}

bb4: {
_0 = const 2_i16;
goto -> bb5;
}

bb5: {
return;
}
}
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41 changes: 18 additions & 23 deletions tests/mir-opt/matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,32 +5,27 @@
debug i => _1;
let mut _0: i16;
let mut _2: u8;
+ let mut _3: u8;

bb0: {
_2 = discriminant(_1);
- switchInt(move _2) -> [1: bb3, 2: bb2, otherwise: bb1];
- }
-
- bb1: {
- unreachable;
- }
-
- bb2: {
- _0 = const 2_i16;
- goto -> bb4;
- }
-
- bb3: {
- _0 = const 1_i16;
- goto -> bb4;
- }
-
- bb4: {
+ StorageLive(_3);
+ _3 = move _2;
+ _0 = _3 as i16 (IntToInt);
+ StorageDead(_3);
switchInt(move _2) -> [1: bb3, 2: bb2, otherwise: bb1];
}

bb1: {
unreachable;
}

bb2: {
_0 = const 2_i16;
goto -> bb4;
}

bb3: {
_0 = const 1_i16;
goto -> bb4;
}

bb4: {
return;
}
}
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51 changes: 23 additions & 28 deletions tests/mir-opt/matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,37 +5,32 @@
debug i => _1;
let mut _0: u16;
let mut _2: u8;
+ let mut _3: u8;

bb0: {
_2 = discriminant(_1);
- switchInt(move _2) -> [1: bb3, 2: bb4, 5: bb2, otherwise: bb1];
- }
-
- bb1: {
- unreachable;
- }
-
- bb2: {
- _0 = const 5_u16;
- goto -> bb5;
- }
-
- bb3: {
- _0 = const 1_u16;
- goto -> bb5;
- }
-
- bb4: {
- _0 = const 2_u16;
- goto -> bb5;
- }
-
- bb5: {
+ StorageLive(_3);
+ _3 = move _2;
+ _0 = _3 as u16 (IntToInt);
+ StorageDead(_3);
switchInt(move _2) -> [1: bb3, 2: bb4, 5: bb2, otherwise: bb1];
}

bb1: {
unreachable;
}

bb2: {
_0 = const 5_u16;
goto -> bb5;
}

bb3: {
_0 = const 1_u16;
goto -> bb5;
}

bb4: {
_0 = const 2_u16;
goto -> bb5;
}

bb5: {
return;
}
}
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20 changes: 5 additions & 15 deletions tests/mir-opt/matches_reduce_branches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,9 +75,7 @@ enum EnumAu8 {
// EMIT_MIR matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff
fn match_u8_i16(i: EnumAu8) -> i16 {
// CHECK-LABEL: fn match_u8_i16(
// CHECK-NOT: switchInt
// CHECK: _0 = _3 as i16 (IntToInt);
// CHECH: return
// CHECK: switchInt
match i {
EnumAu8::A => 1,
EnumAu8::B => 2,
Expand Down Expand Up @@ -146,9 +144,7 @@ enum EnumBu8 {
// EMIT_MIR matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff
fn match_u8_u16(i: EnumBu8) -> u16 {
// CHECK-LABEL: fn match_u8_u16(
// CHECK-NOT: switchInt
// CHECK: _0 = _3 as u16 (IntToInt);
// CHECH: return
// CHECK: switchInt
match i {
EnumBu8::A => 1,
EnumBu8::B => 2,
Expand Down Expand Up @@ -204,9 +200,7 @@ enum EnumAi8 {
// EMIT_MIR matches_reduce_branches.match_i8_i16.MatchBranchSimplification.diff
fn match_i8_i16(i: EnumAi8) -> i16 {
// CHECK-LABEL: fn match_i8_i16(
// CHECK-NOT: switchInt
// CHECK: _0 = _3 as i16 (IntToInt);
// CHECH: return
// CHECK: switchInt
match i {
EnumAi8::A => -1,
EnumAi8::B => 2,
Expand Down Expand Up @@ -235,9 +229,7 @@ enum EnumAi16 {
// EMIT_MIR matches_reduce_branches.match_i16_i8.MatchBranchSimplification.diff
fn match_i16_i8(i: EnumAi16) -> i8 {
// CHECK-LABEL: fn match_i16_i8(
// CHECK-NOT: switchInt
// CHECK: _0 = _3 as i8 (IntToInt);
// CHECH: return
// CHECK: switchInt
match i {
EnumAi16::A => -1,
EnumAi16::B => 2,
Expand All @@ -256,9 +248,7 @@ enum EnumAi128 {
// EMIT_MIR matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff
fn match_i128_u128(i: EnumAi128) -> u128 {
// CHECK-LABEL: fn match_i128_u128(
// CHECK-NOT: switchInt
// CHECK: _0 = _3 as u128 (IntToInt);
// CHECH: return
// CHECK: switchInt
match i {
EnumAi128::A => 1,
EnumAi128::B => 2,
Expand Down
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