Enable MultipleReturnTerminators by default.

Author: cjgillot

compiler/rustc_mir_transform/src/multiple_return_terminators.rs

@@ -10,7 +10,7 @@ pub struct MultipleReturnTerminators;
 
 impl<'tcx> MirPass<'tcx> for MultipleReturnTerminators {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        sess.mir_opt_level() >= 4
+        sess.mir_opt_level() >= 2
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {

tests/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.panic-abort.mir

@@ -58,7 +58,7 @@ fn num_to_digit(_1: char) -> u32 {
         _0 = move ((_5 as Some).0: u32);
         StorageDead(_6);
         StorageDead(_5);
-        goto -> bb8;
+        return;
     }
 
     bb6: {
@@ -68,10 +68,6 @@ fn num_to_digit(_1: char) -> u32 {
     bb7: {
         StorageDead(_4);
         _0 = const 0_u32;
-        goto -> bb8;
-    }
-
-    bb8: {
         return;
     }
 }

tests/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.panic-unwind.mir

@@ -58,7 +58,7 @@ fn num_to_digit(_1: char) -> u32 {
         _0 = move ((_5 as Some).0: u32);
         StorageDead(_6);
         StorageDead(_5);
-        goto -> bb8;
+        return;
     }
 
     bb6: {
@@ -68,10 +68,6 @@ fn num_to_digit(_1: char) -> u32 {
     bb7: {
         StorageDead(_4);
         _0 = const 0_u32;
-        goto -> bb8;
-    }
-
-    bb8: {
         return;
     }
 }

tests/mir-opt/pre-codegen/chained_comparison.returning.PreCodegen.after.mir

@@ -87,50 +87,46 @@ fn returning(_1: &Blueprint, _2: &Blueprint) -> bool {
         StorageDead(_15);
         StorageDead(_17);
         _0 = const true;
-        goto -> bb11;
+        return;
     }
 
     bb6: {
         StorageDead(_16);
         StorageDead(_15);
         _0 = const false;
         StorageDead(_17);
-        goto -> bb11;
+        return;
     }
 
     bb7: {
         StorageDead(_13);
         StorageDead(_12);
         _0 = const false;
         StorageDead(_14);
-        goto -> bb11;
+        return;
     }
 
     bb8: {
         StorageDead(_10);
         StorageDead(_9);
         _0 = const false;
         StorageDead(_11);
-        goto -> bb11;
+        return;
     }
 
     bb9: {
         StorageDead(_7);
         StorageDead(_6);
         _0 = const false;
         StorageDead(_8);
-        goto -> bb11;
+        return;
     }
 
     bb10: {
         StorageDead(_4);
         StorageDead(_3);
         _0 = const false;
         StorageDead(_5);
-        goto -> bb11;
-    }
-
-    bb11: {
         return;
     }
 }

tests/mir-opt/pre-codegen/try_identity.new.PreCodegen.after.mir

@@ -26,7 +26,7 @@ fn new(_1: Result<T, E>) -> Result<T, E> {
     bb0: {
         StorageLive(_4);
         _2 = discriminant(_1);
-        switchInt(move _2) -> [0: bb1, 1: bb2, otherwise: bb7];
+        switchInt(move _2) -> [0: bb1, 1: bb2, otherwise: bb6];
     }
 
     bb1: {
@@ -43,28 +43,24 @@ fn new(_1: Result<T, E>) -> Result<T, E> {
 
     bb3: {
         _6 = discriminant(_4);
-        switchInt(move _6) -> [0: bb4, 1: bb5, otherwise: bb7];
+        switchInt(move _6) -> [0: bb4, 1: bb5, otherwise: bb6];
     }
 
     bb4: {
         _7 = move ((_4 as Continue).0: T);
         _0 = Result::<T, E>::Ok(_7);
         StorageDead(_4);
-        goto -> bb6;
+        return;
     }
 
     bb5: {
         _8 = move ((_4 as Break).0: E);
         _0 = Result::<T, E>::Err(_8);
         StorageDead(_4);
-        goto -> bb6;
-    }
-
-    bb6: {
         return;
     }
 
-    bb7: {
+    bb6: {
         unreachable;
     }
 }

tests/mir-opt/pre-codegen/try_identity.old.PreCodegen.after.mir

@@ -15,26 +15,22 @@ fn old(_1: Result<T, E>) -> Result<T, E> {
 
     bb0: {
         _2 = discriminant(_1);
-        switchInt(move _2) -> [0: bb1, 1: bb2, otherwise: bb4];
+        switchInt(move _2) -> [0: bb1, 1: bb2, otherwise: bb3];
     }
 
     bb1: {
         _3 = move ((_1 as Ok).0: T);
         _0 = Result::<T, E>::Ok(_3);
-        goto -> bb3;
+        return;
     }
 
     bb2: {
         _4 = move ((_1 as Err).0: E);
         _0 = Result::<T, E>::Err(_4);
-        goto -> bb3;
-    }
-
-    bb3: {
         return;
     }
 
-    bb4: {
+    bb3: {
         unreachable;
     }
 }