Transforms match into an assignment statement

7 files changed, 141 insertions, 110 deletions

diff --git a/tests/codegen/match-optimized.rs b/tests/codegen/match-optimized.rs
index 09907edf8f2..5cecafb9f29 100644
--- a/tests/codegen/match-optimized.rs
+++ b/tests/codegen/match-optimized.rs
@@ -26,12 +26,12 @@ pub fn exhaustive_match(e: E) -> u8 {
 // CHECK-NEXT: store i8 1, ptr %_0, align 1
 // CHECK-NEXT: br label %[[EXIT]]
 // CHECK: [[C]]:
-// CHECK-NEXT: store i8 2, ptr %_0, align 1
+// CHECK-NEXT: store i8 3, ptr %_0, align 1
 // CHECK-NEXT: br label %[[EXIT]]
     match e {
         E::A => 0,
         E::B => 1,
-        E::C => 2,
+        E::C => 3,
     }
 }
 
diff --git a/tests/mir-opt/matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff b/tests/mir-opt/matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff
index 1f20349fdec..31ce51dc6de 100644
--- a/tests/mir-opt/matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff
+++ b/tests/mir-opt/matches_reduce_branches.match_i128_u128.MatchBranchSimplification.diff
@@ -5,37 +5,42 @@
       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: {
+-         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);
           return;
       }
   }
diff --git a/tests/mir-opt/matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff b/tests/mir-opt/matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff
index 72ad60956ab..9ee01a87a91 100644
--- a/tests/mir-opt/matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff
+++ b/tests/mir-opt/matches_reduce_branches.match_u8_i16.MatchBranchSimplification.diff
@@ -5,27 +5,32 @@
       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: {
+-         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);
           return;
       }
   }
diff --git a/tests/mir-opt/matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff b/tests/mir-opt/matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff
index 043fdb197a3..aa9fcc60a3e 100644
--- a/tests/mir-opt/matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff
+++ b/tests/mir-opt/matches_reduce_branches.match_u8_u16.MatchBranchSimplification.diff
@@ -5,32 +5,37 @@
       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: {
+-         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);
           return;
       }
   }
diff --git a/tests/mir-opt/matches_reduce_branches.rs b/tests/mir-opt/matches_reduce_branches.rs
index 2e7b7d4e600..d51dd7c5873 100644
--- a/tests/mir-opt/matches_reduce_branches.rs
+++ b/tests/mir-opt/matches_reduce_branches.rs
@@ -75,7 +75,9 @@ 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: switchInt
+    // CHECK-NOT: switchInt
+    // CHECK: _0 = _3 as i16 (IntToInt);
+    // CHECH: return
     match i {
         EnumAu8::A => 1,
         EnumAu8::B => 2,
@@ -144,7 +146,9 @@ 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: switchInt
+    // CHECK-NOT: switchInt
+    // CHECK: _0 = _3 as u16 (IntToInt);
+    // CHECH: return
     match i {
         EnumBu8::A => 1,
         EnumBu8::B => 2,
@@ -248,7 +252,9 @@ 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: switchInt
+    // CHECK-NOT: switchInt
+    // CHECK: _0 = _3 as u128 (IntToInt);
+    // CHECH: return
     match i {
         EnumAi128::A => 1,
         EnumAi128::B => 2,
diff --git a/tests/mir-opt/matches_u8.exhaustive_match.MatchBranchSimplification.diff b/tests/mir-opt/matches_u8.exhaustive_match.MatchBranchSimplification.diff
index 157f9c98353..11a18f58e3a 100644
--- a/tests/mir-opt/matches_u8.exhaustive_match.MatchBranchSimplification.diff
+++ b/tests/mir-opt/matches_u8.exhaustive_match.MatchBranchSimplification.diff
@@ -5,27 +5,32 @@
       debug e => _1;
       let mut _0: u8;
       let mut _2: isize;
++     let mut _3: isize;
   
       bb0: {
           _2 = discriminant(_1);
-          switchInt(move _2) -> [0: bb3, 1: bb2, otherwise: bb1];
-      }
-  
-      bb1: {
-          unreachable;
-      }
-  
-      bb2: {
-          _0 = const 1_u8;
-          goto -> bb4;
-      }
-  
-      bb3: {
-          _0 = const 0_u8;
-          goto -> bb4;
-      }
-  
-      bb4: {
+-         switchInt(move _2) -> [0: bb3, 1: bb2, otherwise: bb1];
+-     }
+- 
+-     bb1: {
+-         unreachable;
+-     }
+- 
+-     bb2: {
+-         _0 = const 1_u8;
+-         goto -> bb4;
+-     }
+- 
+-     bb3: {
+-         _0 = const 0_u8;
+-         goto -> bb4;
+-     }
+- 
+-     bb4: {
++         StorageLive(_3);
++         _3 = move _2;
++         _0 = _3 as u8 (IntToInt);
++         StorageDead(_3);
           return;
       }
   }
diff --git a/tests/mir-opt/matches_u8.exhaustive_match_i8.MatchBranchSimplification.diff b/tests/mir-opt/matches_u8.exhaustive_match_i8.MatchBranchSimplification.diff
index 19083771fd9..809badc41ba 100644
--- a/tests/mir-opt/matches_u8.exhaustive_match_i8.MatchBranchSimplification.diff
+++ b/tests/mir-opt/matches_u8.exhaustive_match_i8.MatchBranchSimplification.diff
@@ -5,27 +5,32 @@
       debug e => _1;
       let mut _0: i8;
       let mut _2: isize;
++     let mut _3: isize;
   
       bb0: {
           _2 = discriminant(_1);
-          switchInt(move _2) -> [0: bb3, 1: bb2, otherwise: bb1];
-      }
-  
-      bb1: {
-          unreachable;
-      }
-  
-      bb2: {
-          _0 = const 1_i8;
-          goto -> bb4;
-      }
-  
-      bb3: {
-          _0 = const 0_i8;
-          goto -> bb4;
-      }
-  
-      bb4: {
+-         switchInt(move _2) -> [0: bb3, 1: bb2, otherwise: bb1];
+-     }
+- 
+-     bb1: {
+-         unreachable;
+-     }
+- 
+-     bb2: {
+-         _0 = const 1_i8;
+-         goto -> bb4;
+-     }
+- 
+-     bb3: {
+-         _0 = const 0_i8;
+-         goto -> bb4;
+-     }
+- 
+-     bb4: {
++         StorageLive(_3);
++         _3 = move _2;
++         _0 = _3 as i8 (IntToInt);
++         StorageDead(_3);
           return;
       }
   }