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Correct the unsoundness in the EarlyOtherwiseBranch mir opt
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This optimization pass previously made excessive assumptions as to the nature of
the blocks being optimized. We remove those assumptions and make sure to
rigorously justify all changes that are made to the MIR. Details can be found
in the file.
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@JakobDegen
JakobDegen committed Dec 14, 2021
1 parent 229d0a9 commit 709c94a
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Showing 10 changed files with 421 additions and 371 deletions.
581 changes: 307 additions & 274 deletions compiler/rustc_mir_transform/src/early_otherwise_branch.rs
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10 changes: 5 additions & 5 deletions src/test/mir-opt/early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -12,8 +12,8 @@
let mut _7: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:5:10: 5:17
let _8: u32; // in scope 0 at $DIR/early_otherwise_branch.rs:5:15: 5:16
let _9: u32; // in scope 0 at $DIR/early_otherwise_branch.rs:5:24: 5:25
+ let mut _10: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:5:19: 5:26
+ let mut _11: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:5:19: 5:26
+ let mut _10: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ let mut _11: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
scope 1 {
debug a => _8; // in scope 1 at $DIR/early_otherwise_branch.rs:5:15: 5:16
debug b => _9; // in scope 1 at $DIR/early_otherwise_branch.rs:5:24: 5:25
Expand All @@ -34,7 +34,7 @@
+ StorageLive(_10); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ _10 = discriminant((_3.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ StorageLive(_11); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ _11 = Ne(_10, _7); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ _11 = Ne(_7, move _10); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ StorageDead(_10); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ switchInt(move _11) -> [false: bb4, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
}
Expand Down Expand Up @@ -70,8 +70,8 @@
+ }
+
+ bb4: {
+ StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch.rs:5:19: 5:26
+ switchInt(_7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:5:19: 5:26
+ StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
+ switchInt(_7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
}
}

10 changes: 5 additions & 5 deletions src/test/mir-opt/early_otherwise_branch.opt2.EarlyOtherwiseBranch.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,8 @@
let mut _8: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:13:10: 13:17
let _9: u32; // in scope 0 at $DIR/early_otherwise_branch.rs:13:15: 13:16
let _10: u32; // in scope 0 at $DIR/early_otherwise_branch.rs:13:24: 13:25
+ let mut _11: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:14:16: 14:20
+ let mut _12: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:14:16: 14:20
+ let mut _11: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ let mut _12: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
scope 1 {
debug a => _9; // in scope 1 at $DIR/early_otherwise_branch.rs:13:15: 13:16
debug b => _10; // in scope 1 at $DIR/early_otherwise_branch.rs:13:24: 13:25
Expand All @@ -35,7 +35,7 @@
+ StorageLive(_11); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ _11 = discriminant((_3.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ StorageLive(_12); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ _12 = Ne(_11, _8); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ _12 = Ne(_8, move _11); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ switchInt(move _12) -> [false: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
}
Expand Down Expand Up @@ -84,8 +84,8 @@
+ }
+
+ bb5: {
+ StorageDead(_12); // scope 0 at $DIR/early_otherwise_branch.rs:14:16: 14:20
+ switchInt(_8) -> [0_isize: bb3, 1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:14:16: 14:20
+ StorageDead(_12); // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+ switchInt(_8) -> [0_isize: bb3, 1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
}
}

77 changes: 77 additions & 0 deletions src/test/mir-opt/early_otherwise_branch.opt3.EarlyOtherwiseBranch.diff
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Original file line number Diff line number Diff line change
@@ -0,0 +1,77 @@
- // MIR for `opt3` before EarlyOtherwiseBranch
+ // MIR for `opt3` after EarlyOtherwiseBranch

fn opt3(_1: Option<u32>, _2: Option<bool>) -> u32 {
debug x => _1; // in scope 0 at $DIR/early_otherwise_branch.rs:21:9: 21:10
debug y => _2; // in scope 0 at $DIR/early_otherwise_branch.rs:21:25: 21:26
let mut _0: u32; // return place in scope 0 at $DIR/early_otherwise_branch.rs:21:45: 21:48
let mut _3: (std::option::Option<u32>, std::option::Option<bool>); // in scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
let mut _4: std::option::Option<u32>; // in scope 0 at $DIR/early_otherwise_branch.rs:22:12: 22:13
let mut _5: std::option::Option<bool>; // in scope 0 at $DIR/early_otherwise_branch.rs:22:15: 22:16
let mut _6: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:23:19: 23:26
let mut _7: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:23:10: 23:17
let _8: u32; // in scope 0 at $DIR/early_otherwise_branch.rs:23:15: 23:16
let _9: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:23:24: 23:25
+ let mut _10: isize; // in scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ let mut _11: bool; // in scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
scope 1 {
debug a => _8; // in scope 1 at $DIR/early_otherwise_branch.rs:23:15: 23:16
debug b => _9; // in scope 1 at $DIR/early_otherwise_branch.rs:23:24: 23:25
}

bb0: {
StorageLive(_3); // scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
StorageLive(_4); // scope 0 at $DIR/early_otherwise_branch.rs:22:12: 22:13
_4 = _1; // scope 0 at $DIR/early_otherwise_branch.rs:22:12: 22:13
StorageLive(_5); // scope 0 at $DIR/early_otherwise_branch.rs:22:15: 22:16
_5 = _2; // scope 0 at $DIR/early_otherwise_branch.rs:22:15: 22:16
(_3.0: std::option::Option<u32>) = move _4; // scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
(_3.1: std::option::Option<bool>) = move _5; // scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
StorageDead(_5); // scope 0 at $DIR/early_otherwise_branch.rs:22:16: 22:17
StorageDead(_4); // scope 0 at $DIR/early_otherwise_branch.rs:22:16: 22:17
_7 = discriminant((_3.0: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
- switchInt(move _7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ StorageLive(_10); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ _10 = discriminant((_3.1: std::option::Option<bool>)); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ StorageLive(_11); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ _11 = Ne(_7, move _10); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ StorageDead(_10); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ switchInt(move _11) -> [false: bb4, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
}

bb1: {
+ StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch.rs:24:14: 24:15
_0 = const 1_u32; // scope 0 at $DIR/early_otherwise_branch.rs:24:14: 24:15
- goto -> bb4; // scope 0 at $DIR/early_otherwise_branch.rs:24:14: 24:15
+ goto -> bb3; // scope 0 at $DIR/early_otherwise_branch.rs:24:14: 24:15
}

bb2: {
- _6 = discriminant((_3.1: std::option::Option<bool>)); // scope 0 at $DIR/early_otherwise_branch.rs:22:11: 22:17
- switchInt(move _6) -> [1_isize: bb3, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
- }
-
- bb3: {
StorageLive(_8); // scope 0 at $DIR/early_otherwise_branch.rs:23:15: 23:16
_8 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:23:15: 23:16
StorageLive(_9); // scope 0 at $DIR/early_otherwise_branch.rs:23:24: 23:25
_9 = (((_3.1: std::option::Option<bool>) as Some).0: bool); // scope 0 at $DIR/early_otherwise_branch.rs:23:24: 23:25
_0 = const 0_u32; // scope 1 at $DIR/early_otherwise_branch.rs:23:31: 23:32
StorageDead(_9); // scope 0 at $DIR/early_otherwise_branch.rs:23:31: 23:32
StorageDead(_8); // scope 0 at $DIR/early_otherwise_branch.rs:23:31: 23:32
- goto -> bb4; // scope 0 at $DIR/early_otherwise_branch.rs:23:31: 23:32
+ goto -> bb3; // scope 0 at $DIR/early_otherwise_branch.rs:23:31: 23:32
}

- bb4: {
+ bb3: {
StorageDead(_3); // scope 0 at $DIR/early_otherwise_branch.rs:26:1: 26:2
return; // scope 0 at $DIR/early_otherwise_branch.rs:26:2: 26:2
+ }
+
+ bb4: {
+ StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
+ switchInt(_7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
}
}

10 changes: 10 additions & 0 deletions src/test/mir-opt/early_otherwise_branch.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,17 @@ fn opt2(x: Option<u32>, y: Option<u32>) -> u32 {
}
}

// optimize despite different types
// EMIT_MIR early_otherwise_branch.opt3.EarlyOtherwiseBranch.diff
fn opt3(x: Option<u32>, y: Option<bool>) -> u32 {
match (x, y) {
(Some(a), Some(b)) => 0,
_ => 1,
}
}

fn main() {
opt1(None, Some(0));
opt2(None, Some(0));
opt3(None, Some(false));
}
14 changes: 7 additions & 7 deletions src/test/mir-opt/early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,10 @@
let _11: u32; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
let _12: u32; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
let _13: u32; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:33: 6:34
+ let mut _14: isize; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:19: 6:26
+ let mut _15: bool; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:19: 6:26
+ let mut _16: isize; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:28: 6:35
+ let mut _17: bool; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:28: 6:35
+ let mut _14: isize; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ let mut _15: bool; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ let mut _16: isize; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ let mut _17: bool; // in scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
scope 1 {
debug a => _11; // in scope 1 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
debug b => _12; // in scope 1 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
Expand All @@ -45,7 +45,7 @@
+ StorageLive(_14); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ _14 = discriminant((_4.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ StorageLive(_15); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ _15 = Ne(_14, _10); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ _15 = Ne(_10, move _14); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ StorageDead(_14); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ switchInt(move _15) -> [false: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
}
Expand Down Expand Up @@ -92,8 +92,8 @@
+ }
+
+ bb5: {
+ StorageDead(_15); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:19: 6:26
+ switchInt(_10) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:19: 6:26
+ StorageDead(_15); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
+ switchInt(_10) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
}
}

10 changes: 5 additions & 5 deletions ..._branch_68867.try_sum.EarlyOtherwiseBranch.before-SimplifyConstCondition-final.after.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,8 @@
let mut _31: f32; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:25:50: 25:55
let mut _32: !; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:26:14: 26:28
let mut _33: (); // in scope 0 at $DIR/early_otherwise_branch_68867.rs:26:25: 26:27
+ let mut _34: isize; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ let mut _35: bool; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ let mut _34: isize; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ let mut _35: bool; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
scope 1 {
- debug one => _12; // in scope 1 at $DIR/early_otherwise_branch_68867.rs:22:14: 22:17
- debug other => _13; // in scope 1 at $DIR/early_otherwise_branch_68867.rs:22:24: 22:29
Expand Down Expand Up @@ -85,7 +85,7 @@
+ StorageLive(_34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _34 = discriminant((*(_4.1: &ViewportPercentageLength))); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ StorageLive(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _35 = Ne(_34, _11); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _35 = Ne(_11, move _34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ StorageDead(_34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ switchInt(move _35) -> [false: bb7, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
}
Expand Down Expand Up @@ -293,8 +293,8 @@
- StorageDead(_3); // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:6: 27:7
- StorageDead(_4); // scope 0 at $DIR/early_otherwise_branch_68867.rs:28:1: 28:2
- return; // scope 0 at $DIR/early_otherwise_branch_68867.rs:28:2: 28:2
+ StorageDead(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ switchInt(_11) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, 3_isize: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ StorageDead(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ switchInt(_11) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, 3_isize: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
}
}

10 changes: 5 additions & 5 deletions src/test/mir-opt/early_otherwise_branch_68867.try_sum.EarlyOtherwiseBranch.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,8 @@
let mut _31: f32; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:25:50: 25:55
let mut _32: !; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:26:14: 26:28
let mut _33: (); // in scope 0 at $DIR/early_otherwise_branch_68867.rs:26:25: 26:27
+ let mut _34: isize; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ let mut _35: bool; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ let mut _34: isize; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ let mut _35: bool; // in scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
scope 1 {
debug one => _12; // in scope 1 at $DIR/early_otherwise_branch_68867.rs:22:14: 22:17
debug other => _13; // in scope 1 at $DIR/early_otherwise_branch_68867.rs:22:24: 22:29
Expand Down Expand Up @@ -71,7 +71,7 @@
+ StorageLive(_34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _34 = discriminant((*(_4.1: &ViewportPercentageLength))); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ StorageLive(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _35 = Ne(_34, _11); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ _35 = Ne(_11, move _34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ StorageDead(_34); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ switchInt(move _35) -> [false: bb7, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
}
Expand Down Expand Up @@ -209,8 +209,8 @@
+ }
+
+ bb7: {
+ StorageDead(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ switchInt(_11) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, 3_isize: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:22:21: 22:30
+ StorageDead(_35); // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
+ switchInt(_11) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, 3_isize: bb5, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_68867.rs:21:8: 21:24
}
}

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