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Turn on UnreachablePropagation by default #77680

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8ca4f65
Turn on UnreachablePropagation by default
jonas-schievink Oct 7, 2020
84a8cfe
Bless mir-opt tests
jonas-schievink Oct 8, 2020
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8 changes: 1 addition & 7 deletions compiler/rustc_mir/src/transform/unreachable_prop.rs
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Expand Up @@ -12,13 +12,7 @@ use std::borrow::Cow;
pub struct UnreachablePropagation;

impl MirPass<'_> for UnreachablePropagation {
fn run_pass<'tcx>(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
if tcx.sess.opts.debugging_opts.mir_opt_level < 3 {
// Enable only under -Zmir-opt-level=3 as in some cases (check the deeply-nested-opt
// perf benchmark) LLVM may spend quite a lot of time optimizing the generated code.
return;
}

fn run_pass<'tcx>(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let mut unreachable_blocks = FxHashSet::default();
let mut replacements = FxHashMap::default();

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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id.SimplifyArmIdentity.diff
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Expand Up @@ -14,19 +14,15 @@

bb0: {
_2 = discriminant(_1); // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
switchInt(move _2) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
switchInt(move _2) -> [0_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
}

bb1: {
discriminant(_0) = 0; // scope 0 at $DIR/simplify-arm.rs:12:17: 12:21
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
}

bb2: {
unreachable; // scope 0 at $DIR/simplify-arm.rs:10:11: 10:12
}

bb3: {
- StorageLive(_3); // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
- _3 = ((_1 as Some).0: u8); // scope 0 at $DIR/simplify-arm.rs:11:14: 11:15
- StorageLive(_4); // scope 1 at $DIR/simplify-arm.rs:11:25: 11:26
Expand All @@ -36,10 +32,10 @@
- StorageDead(_4); // scope 1 at $DIR/simplify-arm.rs:11:26: 11:27
- StorageDead(_3); // scope 0 at $DIR/simplify-arm.rs:11:26: 11:27
+ _0 = move _1; // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
}

bb4: {
bb3: {
return; // scope 0 at $DIR/simplify-arm.rs:14:2: 14:2
}
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id.SimplifyBranchSame.diff
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Expand Up @@ -13,26 +13,22 @@

bb0: {
_2 = discriminant(_1); // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
- switchInt(move _2) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
- switchInt(move _2) -> [0_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
+ goto -> bb1; // scope 0 at $DIR/simplify-arm.rs:11:9: 11:16
}

bb1: {
- discriminant(_0) = 0; // scope 0 at $DIR/simplify-arm.rs:12:17: 12:21
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
- }
-
- bb2: {
- unreachable; // scope 0 at $DIR/simplify-arm.rs:10:11: 10:12
- }
-
- bb3: {
_0 = move _1; // scope 1 at $DIR/simplify-arm.rs:11:20: 11:27
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
+ goto -> bb2; // scope 0 at $DIR/simplify-arm.rs:10:5: 13:6
}

- bb4: {
- bb3: {
+ bb2: {
return; // scope 0 at $DIR/simplify-arm.rs:14:2: 14:2
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id_result.SimplifyArmIdentity.diff
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Expand Up @@ -20,7 +20,7 @@

bb0: {
_2 = discriminant(_1); // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
switchInt(move _2) -> [0_isize: bb3, 1_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
switchInt(move _2) -> [0_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
}

bb1: {
Expand All @@ -33,14 +33,10 @@
- StorageDead(_6); // scope 2 at $DIR/simplify-arm.rs:19:24: 19:25
- StorageDead(_5); // scope 0 at $DIR/simplify-arm.rs:19:24: 19:25
+ _0 = move _1; // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
}

bb2: {
unreachable; // scope 0 at $DIR/simplify-arm.rs:17:11: 17:12
}

bb3: {
- StorageLive(_3); // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
- _3 = ((_1 as Ok).0: u8); // scope 0 at $DIR/simplify-arm.rs:18:12: 18:13
- StorageLive(_4); // scope 1 at $DIR/simplify-arm.rs:18:21: 18:22
Expand All @@ -50,10 +46,10 @@
- StorageDead(_4); // scope 1 at $DIR/simplify-arm.rs:18:22: 18:23
- StorageDead(_3); // scope 0 at $DIR/simplify-arm.rs:18:22: 18:23
+ _0 = move _1; // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
}

bb4: {
bb3: {
return; // scope 0 at $DIR/simplify-arm.rs:21:2: 21:2
}
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id_result.SimplifyBranchSame.diff
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Expand Up @@ -18,26 +18,22 @@

bb0: {
_2 = discriminant(_1); // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
- switchInt(move _2) -> [0_isize: bb3, 1_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
- switchInt(move _2) -> [0_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
+ goto -> bb1; // scope 0 at $DIR/simplify-arm.rs:18:9: 18:14
}

bb1: {
- _0 = move _1; // scope 2 at $DIR/simplify-arm.rs:19:19: 19:25
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
- }
-
- bb2: {
- unreachable; // scope 0 at $DIR/simplify-arm.rs:17:11: 17:12
- }
-
- bb3: {
_0 = move _1; // scope 1 at $DIR/simplify-arm.rs:18:18: 18:23
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
+ goto -> bb2; // scope 0 at $DIR/simplify-arm.rs:17:5: 20:6
}

- bb4: {
- bb3: {
+ bb2: {
return; // scope 0 at $DIR/simplify-arm.rs:21:2: 21:2
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id_try.SimplifyArmIdentity.diff
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Expand Up @@ -51,7 +51,7 @@
_3 = move _4; // scope 6 at $SRC_DIR/core/src/result.rs:LL:COL
StorageDead(_4); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
_5 = discriminant(_3); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
switchInt(move _5) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
switchInt(move _5) -> [0_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
}

bb1: {
Expand All @@ -67,14 +67,10 @@
- discriminant(_0) = 0; // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
- StorageDead(_11); // scope 1 at $DIR/simplify-arm.rs:25:9: 25:10
StorageDead(_2); // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
}

bb2: {
unreachable; // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
}

bb3: {
- StorageLive(_6); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
- _6 = ((_3 as Err).0: i32); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
- StorageLive(_8); // scope 3 at $DIR/simplify-arm.rs:24:14: 24:15
Expand All @@ -92,10 +88,10 @@
+ _0 = move _3; // scope 8 at $SRC_DIR/core/src/result.rs:LL:COL
StorageDead(_3); // scope 0 at $DIR/simplify-arm.rs:24:15: 24:16
StorageDead(_2); // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
}

bb4: {
bb3: {
return; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
}
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm.id_try.SimplifyBranchSame.diff
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Expand Up @@ -46,30 +46,26 @@
_3 = move _4; // scope 6 at $SRC_DIR/core/src/result.rs:LL:COL
StorageDead(_4); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
_5 = discriminant(_3); // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
- switchInt(move _5) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
- switchInt(move _5) -> [0_isize: bb1, otherwise: bb2]; // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
+ goto -> bb1; // scope 0 at $DIR/simplify-arm.rs:24:14: 24:15
}

bb1: {
_0 = move _3; // scope 1 at $DIR/simplify-arm.rs:25:5: 25:10
StorageDead(_3); // scope 0 at $DIR/simplify-arm.rs:24:15: 24:16
StorageDead(_2); // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
+ goto -> bb2; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
}

bb2: {
- unreachable; // scope 0 at $DIR/simplify-arm.rs:24:13: 24:15
- }
-
- bb3: {
- _0 = move _3; // scope 8 at $SRC_DIR/core/src/result.rs:LL:COL
- StorageDead(_3); // scope 0 at $DIR/simplify-arm.rs:24:15: 24:16
- StorageDead(_2); // scope 0 at $DIR/simplify-arm.rs:26:1: 26:2
- goto -> bb4; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
- goto -> bb3; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
- }
-
- bb4: {
- bb3: {
return; // scope 0 at $DIR/simplify-arm.rs:26:2: 26:2
}
}
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12 changes: 4 additions & 8 deletions src/test/mir-opt/simplify_arm_identity.main.SimplifyArmIdentity.64bit.diff
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Expand Up @@ -23,20 +23,16 @@
discriminant(_1) = 0; // scope 0 at $DIR/simplify-arm-identity.rs:18:18: 18:29
StorageLive(_2); // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
_3 = const 0_isize; // scope 1 at $DIR/simplify-arm-identity.rs:20:9: 20:20
goto -> bb3; // scope 1 at $DIR/simplify-arm-identity.rs:20:9: 20:20
goto -> bb2; // scope 1 at $DIR/simplify-arm-identity.rs:20:9: 20:20
}

bb1: {
((_2 as Foo).0: u8) = const 0_u8; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
discriminant(_2) = 0; // scope 1 at $DIR/simplify-arm-identity.rs:21:21: 21:32
goto -> bb4; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
goto -> bb3; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
}

bb2: {
unreachable; // scope 1 at $DIR/simplify-arm-identity.rs:19:24: 19:25
}

bb3: {
StorageLive(_4); // scope 1 at $DIR/simplify-arm-identity.rs:20:18: 20:19
_4 = ((_1 as Foo).0: u8); // scope 1 at $DIR/simplify-arm-identity.rs:20:18: 20:19
StorageLive(_5); // scope 3 at $DIR/simplify-arm-identity.rs:20:33: 20:34
Expand All @@ -45,10 +41,10 @@
discriminant(_2) = 0; // scope 3 at $DIR/simplify-arm-identity.rs:20:24: 20:35
StorageDead(_5); // scope 3 at $DIR/simplify-arm-identity.rs:20:34: 20:35
StorageDead(_4); // scope 1 at $DIR/simplify-arm-identity.rs:20:34: 20:35
goto -> bb4; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
goto -> bb3; // scope 1 at $DIR/simplify-arm-identity.rs:19:18: 22:6
}

bb4: {
bb3: {
StorageDead(_2); // scope 1 at $DIR/simplify-arm-identity.rs:22:6: 22:7
_0 = const (); // scope 0 at $DIR/simplify-arm-identity.rs:17:11: 23:2
StorageDead(_1); // scope 0 at $DIR/simplify-arm-identity.rs:23:1: 23:2
Expand Down