From b56ea88414ebd87051b69f27ff3ed55fe0ec12fc Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Fri, 24 Jul 2020 15:54:15 +0200
Subject: [PATCH] Add a system for creating diffs across multiple mir
 optimizations.

---
 src/test/mir-opt/match-arm-scopes.rs          |   3 +-
 ...complicated_match.ElaborateDrops.after.mir | 235 -------------
 ...fg-initial.after-ElaborateDrops.after.diff | 313 ++++++++++++++++++
 ...icated_match.SimplifyCfg-initial.after.mir | 246 --------------
 src/tools/compiletest/src/runtest.rs          |  53 ++-
 5 files changed, 357 insertions(+), 493 deletions(-)
 delete mode 100644 src/test/mir-opt/match-arm-scopes/rustc.complicated_match.ElaborateDrops.after.mir
 create mode 100644 src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after-ElaborateDrops.after.diff
 delete mode 100644 src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after.mir

diff --git a/src/test/mir-opt/match-arm-scopes.rs b/src/test/mir-opt/match-arm-scopes.rs
index 0e30a15671528..2c5816c51e3e2 100644
--- a/src/test/mir-opt/match-arm-scopes.rs
+++ b/src/test/mir-opt/match-arm-scopes.rs
@@ -9,8 +9,7 @@
 //   all of the bindings for that scope.
 // * No drop flags are used.
 
-// EMIT_MIR rustc.complicated_match.SimplifyCfg-initial.after.mir
-// EMIT_MIR rustc.complicated_match.ElaborateDrops.after.mir
+// EMIT_MIR rustc.complicated_match SimplifyCfg-initial.after ElaborateDrops.after
 fn complicated_match(cond: bool, items: (bool, bool, String)) -> i32 {
     match items {
         (false, a, s) | (a, false, s) if if cond { return 3 } else { a } => 1,
diff --git a/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.ElaborateDrops.after.mir b/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.ElaborateDrops.after.mir
deleted file mode 100644
index df6a247bb5ff6..0000000000000
--- a/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.ElaborateDrops.after.mir
+++ /dev/null
@@ -1,235 +0,0 @@
-// MIR for `complicated_match` after ElaborateDrops
-
-fn complicated_match(_1: bool, _2: (bool, bool, std::string::String)) -> i32 {
-    debug cond => _1;                    // in scope 0 at $DIR/match-arm-scopes.rs:14:22: 14:26
-    debug items => _2;                   // in scope 0 at $DIR/match-arm-scopes.rs:14:34: 14:39
-    let mut _0: i32;                     // return place in scope 0 at $DIR/match-arm-scopes.rs:14:66: 14:69
-    let mut _3: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-    let mut _4: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-    let _5: bool;                        // in scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-    let _6: &bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-    let _7: std::string::String;         // in scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    let _8: &std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    let mut _9: bool;                    // in scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    let mut _10: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-    let mut _11: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    let mut _12: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    let mut _13: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-    let mut _14: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    let _15: bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-    let _16: std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-    scope 1 {
-        debug a => _5;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        debug a => _6;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        debug s => _7;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        debug s => _8;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    }
-    scope 2 {
-        debug b => _15;                  // in scope 2 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        debug t => _16;                  // in scope 2 at $DIR/match-arm-scopes.rs:17:19: 17:20
-    }
-
-    bb0: {
-        switchInt((_2.0: bool)) -> [false: bb6, otherwise: bb2]; // scope 0 at $DIR/match-arm-scopes.rs:16:10: 16:15
-    }
-
-    bb1 (cleanup): {
-        resume;                          // scope 0 at $DIR/match-arm-scopes.rs:14:1: 19:2
-    }
-
-    bb2: {
-        switchInt((_2.1: bool)) -> [false: bb14, otherwise: bb3]; // scope 0 at $DIR/match-arm-scopes.rs:16:29: 16:34
-    }
-
-    bb3: {
-        switchInt((_2.0: bool)) -> [false: bb4, otherwise: bb21]; // scope 0 at $DIR/match-arm-scopes.rs:17:10: 17:14
-    }
-
-    bb4: {
-        StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:32: 17:33
-        _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:17:32: 17:33
-        StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:35: 17:36
-        _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:17:35: 17:36
-        goto -> bb20;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb5: {
-        _0 = const 1_i32;                // scope 1 at $DIR/match-arm-scopes.rs:16:77: 16:78
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000001))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:77: 16:78
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
-        drop(_7) -> [return: bb19, unwind: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-    }
-
-    bb6: {
-        StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        _6 = &(_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        StorageLive(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-        StorageLive(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        _10 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        switchInt(_10) -> [false: bb7, otherwise: bb8]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb7: {
-        _9 = (*_6);                      // scope 0 at $DIR/match-arm-scopes.rs:16:70: 16:71
-        StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        switchInt(move _9) -> [false: bb13, otherwise: bb12]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb8: {
-        _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb11;                    // scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    }
-
-    bb9: {
-        return;                          // scope 0 at $DIR/match-arm-scopes.rs:19:2: 19:2
-    }
-
-    bb10 (cleanup): {
-        goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb11: {
-        drop(_2) -> [return: bb9, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb12: {
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        _5 = (_2.1: bool);               // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        goto -> bb5;                     // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb13: {
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb2;                     // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb14: {
-        StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        _6 = &(_2.0: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        StorageLive(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-        StorageLive(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        _13 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        switchInt(_13) -> [false: bb15, otherwise: bb16]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb15: {
-        _12 = (*_6);                     // scope 0 at $DIR/match-arm-scopes.rs:16:70: 16:71
-        StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        switchInt(move _12) -> [false: bb18, otherwise: bb17]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb16: {
-        _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb11;                    // scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    }
-
-    bb17: {
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        _5 = (_2.0: bool);               // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        goto -> bb5;                     // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb18: {
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb3;                     // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb19: {
-        StorageDead(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb23;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb20: {
-        _0 = const 2_i32;                // scope 2 at $DIR/match-arm-scopes.rs:17:41: 17:42
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000002))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:17:41: 17:42
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
-        drop(_16) -> [return: bb22, unwind: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-    }
-
-    bb21: {
-        StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-        _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-        goto -> bb20;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb22: {
-        StorageDead(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-        StorageDead(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-        goto -> bb23;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb23: {
-        goto -> bb29;                    // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb24 (cleanup): {
-        goto -> bb1;                     // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb25 (cleanup): {
-        goto -> bb24;                    // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb26: {
-        goto -> bb9;                     // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb27 (cleanup): {
-        goto -> bb1;                     // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb28 (cleanup): {
-        goto -> bb27;                    // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb29: {
-        goto -> bb26;                    // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-}
diff --git a/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after-ElaborateDrops.after.diff b/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after-ElaborateDrops.after.diff
new file mode 100644
index 0000000000000..58847e1bceee6
--- /dev/null
+++ b/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after-ElaborateDrops.after.diff
@@ -0,0 +1,313 @@
+- // MIR for `complicated_match` after SimplifyCfg-initial
++ // MIR for `complicated_match` after ElaborateDrops
+  
+  fn complicated_match(_1: bool, _2: (bool, bool, std::string::String)) -> i32 {
+      debug cond => _1;                    // in scope 0 at $DIR/match-arm-scopes.rs:13:22: 13:26
+      debug items => _2;                   // in scope 0 at $DIR/match-arm-scopes.rs:13:34: 13:39
+      let mut _0: i32;                     // return place in scope 0 at $DIR/match-arm-scopes.rs:13:66: 13:69
+      let mut _3: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+      let mut _4: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+      let _5: bool;                        // in scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+      let _6: &bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+      let _7: std::string::String;         // in scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+      let _8: &std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+      let mut _9: bool;                    // in scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      let mut _10: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+      let mut _11: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
+      let mut _12: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      let mut _13: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+      let mut _14: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
+      let _15: bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:16:16: 16:17
+      let _16: std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:16:19: 16:20
+      scope 1 {
+          debug a => _5;                   // in scope 1 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          debug a => _6;                   // in scope 1 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          debug s => _7;                   // in scope 1 at $DIR/match-arm-scopes.rs:15:20: 15:21
+          debug s => _8;                   // in scope 1 at $DIR/match-arm-scopes.rs:15:20: 15:21
+      }
+      scope 2 {
+          debug b => _15;                  // in scope 2 at $DIR/match-arm-scopes.rs:16:16: 16:17
+          debug t => _16;                  // in scope 2 at $DIR/match-arm-scopes.rs:16:19: 16:20
+      }
+  
+      bb0: {
+-         FakeRead(ForMatchedPlace, _2);   // scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+-         switchInt((_2.0: bool)) -> [false: bb2, otherwise: bb3]; // scope 0 at $DIR/match-arm-scopes.rs:15:10: 15:15
++         switchInt((_2.0: bool)) -> [false: bb6, otherwise: bb2]; // scope 0 at $DIR/match-arm-scopes.rs:15:10: 15:15
+      }
+  
+      bb1 (cleanup): {
+          resume;                          // scope 0 at $DIR/match-arm-scopes.rs:13:1: 18:2
+      }
+  
+      bb2: {
+-         falseEdge -> [real: bb9, imaginary: bb4]; // scope 0 at $DIR/match-arm-scopes.rs:15:9: 15:22
++         switchInt((_2.1: bool)) -> [false: bb14, otherwise: bb3]; // scope 0 at $DIR/match-arm-scopes.rs:15:29: 15:34
+      }
+  
+      bb3: {
+-         switchInt((_2.1: bool)) -> [false: bb4, otherwise: bb5]; // scope 0 at $DIR/match-arm-scopes.rs:15:29: 15:34
++         switchInt((_2.0: bool)) -> [false: bb4, otherwise: bb21]; // scope 0 at $DIR/match-arm-scopes.rs:16:10: 16:14
+      }
+  
+      bb4: {
+-         falseEdge -> [real: bb18, imaginary: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:15:25: 15:38
+-     }
+- 
+-     bb5: {
+-         switchInt((_2.0: bool)) -> [false: bb7, otherwise: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:16:10: 16:14
+-     }
+- 
+-     bb6: {
+-         falseEdge -> [real: bb26, imaginary: bb7]; // scope 0 at $DIR/match-arm-scopes.rs:16:9: 16:21
+-     }
+- 
+-     bb7: {
+          StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:16:32: 16:33
+          _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:32: 16:33
+          StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:16:35: 16:36
+          _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:35: 16:36
+-         goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb20;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb8: {
++     bb5: {
+          _0 = const 1_i32;                // scope 1 at $DIR/match-arm-scopes.rs:15:77: 15:78
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/match-arm-scopes.rs:15:77: 15:78
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
+-         drop(_7) -> [return: bb24, unwind: bb14]; // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
++         drop(_7) -> [return: bb19, unwind: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+      }
+  
+-     bb9: {
++     bb6: {
+          StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          _6 = &(_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+          _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+-         _3 = &shallow (_2.0: bool);      // scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+-         _4 = &shallow (_2.1: bool);      // scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+          StorageLive(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+          StorageLive(_10);                // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+          _10 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+-         FakeRead(ForMatchedPlace, _10);  // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+-         switchInt(_10) -> [false: bb11, otherwise: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         switchInt(_10) -> [false: bb7, otherwise: bb8]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb10: {
+-         falseEdge -> [real: bb12, imaginary: bb11]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+-     }
+- 
+-     bb11: {
++     bb7: {
+          _9 = (*_6);                      // scope 0 at $DIR/match-arm-scopes.rs:15:70: 15:71
+          StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         switchInt(move _9) -> [false: bb17, otherwise: bb16]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         switchInt(move _9) -> [false: bb13, otherwise: bb12]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb12: {
++     bb8: {
+          _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:15:59: 15:60
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000003))
+                                           // mir::Constant
+                                           // + span: $DIR/match-arm-scopes.rs:15:59: 15:60
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
+          StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+          StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         goto -> bb15;                    // scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
++         goto -> bb11;                    // scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
+      }
+  
+-     bb13: {
++     bb9: {
+          return;                          // scope 0 at $DIR/match-arm-scopes.rs:18:2: 18:2
+      }
+  
+-     bb14 (cleanup): {
+-         drop(_2) -> bb1;                 // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     bb10 (cleanup): {
++         goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
+      }
+  
+-     bb15: {
+-         drop(_2) -> [return: bb13, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     bb11: {
++         drop(_2) -> [return: bb9, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
+      }
+  
+-     bb16: {
++     bb12: {
+          StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         FakeRead(ForMatchGuard, _3);     // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForMatchGuard, _4);     // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForGuardBinding, _6);   // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForGuardBinding, _8);   // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+          StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          _5 = (_2.1: bool);               // scope 0 at $DIR/match-arm-scopes.rs:15:17: 15:18
+          StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+          _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:15:20: 15:21
+-         goto -> bb8;                     // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb5;                     // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb17: {
++     bb13: {
+          StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         falseEdge -> [real: bb3, imaginary: bb4]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         goto -> bb2;                     // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb18: {
++     bb14: {
+          StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:26: 15:27
+          _6 = &(_2.0: bool);              // scope 0 at $DIR/match-arm-scopes.rs:15:26: 15:27
+          StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:36: 15:37
+          _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:15:36: 15:37
+-         _3 = &shallow (_2.0: bool);      // scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+-         _4 = &shallow (_2.1: bool);      // scope 0 at $DIR/match-arm-scopes.rs:14:11: 14:16
+          StorageLive(_12);                // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+          StorageLive(_13);                // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+          _13 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+-         FakeRead(ForMatchedPlace, _13);  // scope 0 at $DIR/match-arm-scopes.rs:15:45: 15:49
+-         switchInt(_13) -> [false: bb20, otherwise: bb19]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         switchInt(_13) -> [false: bb15, otherwise: bb16]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb19: {
+-         falseEdge -> [real: bb21, imaginary: bb20]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+-     }
+- 
+-     bb20: {
++     bb15: {
+          _12 = (*_6);                     // scope 0 at $DIR/match-arm-scopes.rs:15:70: 15:71
+          StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         switchInt(move _12) -> [false: bb23, otherwise: bb22]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         switchInt(move _12) -> [false: bb18, otherwise: bb17]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb21: {
++     bb16: {
+          _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:15:59: 15:60
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000003))
+                                           // mir::Constant
+                                           // + span: $DIR/match-arm-scopes.rs:15:59: 15:60
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
+          StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+          StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         goto -> bb15;                    // scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
++         goto -> bb11;                    // scope 0 at $DIR/match-arm-scopes.rs:15:52: 15:60
+      }
+  
+-     bb22: {
++     bb17: {
+          StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         FakeRead(ForMatchGuard, _3);     // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForMatchGuard, _4);     // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForGuardBinding, _6);   // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+-         FakeRead(ForGuardBinding, _8);   // scope 0 at $DIR/match-arm-scopes.rs:15:72: 15:73
+          StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:15:26: 15:27
+          _5 = (_2.0: bool);               // scope 0 at $DIR/match-arm-scopes.rs:15:26: 15:27
+          StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:15:36: 15:37
+          _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:15:36: 15:37
+-         goto -> bb8;                     // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb5;                     // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb23: {
++     bb18: {
+          StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         falseEdge -> [real: bb5, imaginary: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
++         goto -> bb3;                     // scope 0 at $DIR/match-arm-scopes.rs:15:42: 15:73
+      }
+  
+-     bb24: {
++     bb19: {
+          StorageDead(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+          StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:15:77: 15:78
+-         goto -> bb28;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb23;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb25: {
++     bb20: {
+          _0 = const 2_i32;                // scope 2 at $DIR/match-arm-scopes.rs:16:41: 16:42
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000002))
+                                           // mir::Constant
+                                           // + span: $DIR/match-arm-scopes.rs:16:41: 16:42
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
+-         drop(_16) -> [return: bb27, unwind: bb14]; // scope 0 at $DIR/match-arm-scopes.rs:16:41: 16:42
++         drop(_16) -> [return: bb22, unwind: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:16:41: 16:42
+      }
+  
+-     bb26: {
++     bb21: {
+          StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:16:16: 16:17
+          _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:16: 16:17
+          StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:16:19: 16:20
+          _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:19: 16:20
+-         goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb20;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb27: {
++     bb22: {
+          StorageDead(_16);                // scope 0 at $DIR/match-arm-scopes.rs:16:41: 16:42
+          StorageDead(_15);                // scope 0 at $DIR/match-arm-scopes.rs:16:41: 16:42
+-         goto -> bb28;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
++         goto -> bb23;                    // scope 0 at $DIR/match-arm-scopes.rs:14:5: 17:6
+      }
+  
+-     bb28: {
+-         drop(_2) -> [return: bb13, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     bb23: {
++         goto -> bb29;                    // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb24 (cleanup): {
++         goto -> bb1;                     // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb25 (cleanup): {
++         goto -> bb24;                    // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb26: {
++         goto -> bb9;                     // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb27 (cleanup): {
++         goto -> bb1;                     // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb28 (cleanup): {
++         goto -> bb27;                    // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
++     }
++ 
++     bb29: {
++         goto -> bb26;                    // scope 0 at $DIR/match-arm-scopes.rs:18:1: 18:2
+      }
+  }
+  
diff --git a/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after.mir b/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after.mir
deleted file mode 100644
index dadbc3668cb29..0000000000000
--- a/src/test/mir-opt/match-arm-scopes/rustc.complicated_match.SimplifyCfg-initial.after.mir
+++ /dev/null
@@ -1,246 +0,0 @@
-// MIR for `complicated_match` after SimplifyCfg-initial
-
-fn complicated_match(_1: bool, _2: (bool, bool, std::string::String)) -> i32 {
-    debug cond => _1;                    // in scope 0 at $DIR/match-arm-scopes.rs:14:22: 14:26
-    debug items => _2;                   // in scope 0 at $DIR/match-arm-scopes.rs:14:34: 14:39
-    let mut _0: i32;                     // return place in scope 0 at $DIR/match-arm-scopes.rs:14:66: 14:69
-    let mut _3: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-    let mut _4: &bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-    let _5: bool;                        // in scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-    let _6: &bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-    let _7: std::string::String;         // in scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    let _8: &std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    let mut _9: bool;                    // in scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    let mut _10: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-    let mut _11: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    let mut _12: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    let mut _13: bool;                   // in scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-    let mut _14: !;                      // in scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    let _15: bool;                       // in scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-    let _16: std::string::String;        // in scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-    scope 1 {
-        debug a => _5;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        debug a => _6;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        debug s => _7;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        debug s => _8;                   // in scope 1 at $DIR/match-arm-scopes.rs:16:20: 16:21
-    }
-    scope 2 {
-        debug b => _15;                  // in scope 2 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        debug t => _16;                  // in scope 2 at $DIR/match-arm-scopes.rs:17:19: 17:20
-    }
-
-    bb0: {
-        FakeRead(ForMatchedPlace, _2);   // scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-        switchInt((_2.0: bool)) -> [false: bb2, otherwise: bb3]; // scope 0 at $DIR/match-arm-scopes.rs:16:10: 16:15
-    }
-
-    bb1 (cleanup): {
-        resume;                          // scope 0 at $DIR/match-arm-scopes.rs:14:1: 19:2
-    }
-
-    bb2: {
-        falseEdge -> [real: bb9, imaginary: bb4]; // scope 0 at $DIR/match-arm-scopes.rs:16:9: 16:22
-    }
-
-    bb3: {
-        switchInt((_2.1: bool)) -> [false: bb4, otherwise: bb5]; // scope 0 at $DIR/match-arm-scopes.rs:16:29: 16:34
-    }
-
-    bb4: {
-        falseEdge -> [real: bb18, imaginary: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:16:25: 16:38
-    }
-
-    bb5: {
-        switchInt((_2.0: bool)) -> [false: bb7, otherwise: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:17:10: 17:14
-    }
-
-    bb6: {
-        falseEdge -> [real: bb26, imaginary: bb7]; // scope 0 at $DIR/match-arm-scopes.rs:17:9: 17:21
-    }
-
-    bb7: {
-        StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:32: 17:33
-        _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:17:32: 17:33
-        StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:35: 17:36
-        _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:17:35: 17:36
-        goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb8: {
-        _0 = const 1_i32;                // scope 1 at $DIR/match-arm-scopes.rs:16:77: 16:78
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000001))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:77: 16:78
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
-        drop(_7) -> [return: bb24, unwind: bb14]; // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-    }
-
-    bb9: {
-        StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        _6 = &(_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        _3 = &shallow (_2.0: bool);      // scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-        _4 = &shallow (_2.1: bool);      // scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-        StorageLive(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-        StorageLive(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        _10 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        FakeRead(ForMatchedPlace, _10);  // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        switchInt(_10) -> [false: bb11, otherwise: bb10]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb10: {
-        falseEdge -> [real: bb12, imaginary: bb11]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb11: {
-        _9 = (*_6);                      // scope 0 at $DIR/match-arm-scopes.rs:16:70: 16:71
-        StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        switchInt(move _9) -> [false: bb17, otherwise: bb16]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb12: {
-        _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_10);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb15;                    // scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    }
-
-    bb13: {
-        return;                          // scope 0 at $DIR/match-arm-scopes.rs:19:2: 19:2
-    }
-
-    bb14 (cleanup): {
-        drop(_2) -> bb1;                 // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb15: {
-        drop(_2) -> [return: bb13, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-
-    bb16: {
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        FakeRead(ForMatchGuard, _3);     // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForMatchGuard, _4);     // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForGuardBinding, _6);   // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForGuardBinding, _8);   // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        _5 = (_2.1: bool);               // scope 0 at $DIR/match-arm-scopes.rs:16:17: 16:18
-        StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:20: 16:21
-        goto -> bb8;                     // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb17: {
-        StorageDead(_9);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        falseEdge -> [real: bb3, imaginary: bb4]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb18: {
-        StorageLive(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        _6 = &(_2.0: bool);              // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        StorageLive(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        _8 = &(_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        _3 = &shallow (_2.0: bool);      // scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-        _4 = &shallow (_2.1: bool);      // scope 0 at $DIR/match-arm-scopes.rs:15:11: 15:16
-        StorageLive(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-        StorageLive(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        _13 = _1;                        // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        FakeRead(ForMatchedPlace, _13);  // scope 0 at $DIR/match-arm-scopes.rs:16:45: 16:49
-        switchInt(_13) -> [false: bb20, otherwise: bb19]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb19: {
-        falseEdge -> [real: bb21, imaginary: bb20]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb20: {
-        _12 = (*_6);                     // scope 0 at $DIR/match-arm-scopes.rs:16:70: 16:71
-        StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        switchInt(move _12) -> [false: bb23, otherwise: bb22]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb21: {
-        _0 = const 3_i32;                // scope 0 at $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:16:59: 16:60
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_13);                // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb15;                    // scope 0 at $DIR/match-arm-scopes.rs:16:52: 16:60
-    }
-
-    bb22: {
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        FakeRead(ForMatchGuard, _3);     // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForMatchGuard, _4);     // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForGuardBinding, _6);   // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        FakeRead(ForGuardBinding, _8);   // scope 0 at $DIR/match-arm-scopes.rs:16:72: 16:73
-        StorageLive(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        _5 = (_2.0: bool);               // scope 0 at $DIR/match-arm-scopes.rs:16:26: 16:27
-        StorageLive(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        _7 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:16:36: 16:37
-        goto -> bb8;                     // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb23: {
-        StorageDead(_12);                // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        falseEdge -> [real: bb5, imaginary: bb6]; // scope 0 at $DIR/match-arm-scopes.rs:16:42: 16:73
-    }
-
-    bb24: {
-        StorageDead(_7);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_5);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_8);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        StorageDead(_6);                 // scope 0 at $DIR/match-arm-scopes.rs:16:77: 16:78
-        goto -> bb28;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb25: {
-        _0 = const 2_i32;                // scope 2 at $DIR/match-arm-scopes.rs:17:41: 17:42
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000002))
-                                         // mir::Constant
-                                         // + span: $DIR/match-arm-scopes.rs:17:41: 17:42
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
-        drop(_16) -> [return: bb27, unwind: bb14]; // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-    }
-
-    bb26: {
-        StorageLive(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        _15 = (_2.1: bool);              // scope 0 at $DIR/match-arm-scopes.rs:17:16: 17:17
-        StorageLive(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-        _16 = move (_2.2: std::string::String); // scope 0 at $DIR/match-arm-scopes.rs:17:19: 17:20
-        goto -> bb25;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb27: {
-        StorageDead(_16);                // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-        StorageDead(_15);                // scope 0 at $DIR/match-arm-scopes.rs:17:41: 17:42
-        goto -> bb28;                    // scope 0 at $DIR/match-arm-scopes.rs:15:5: 18:6
-    }
-
-    bb28: {
-        drop(_2) -> [return: bb13, unwind: bb1]; // scope 0 at $DIR/match-arm-scopes.rs:19:1: 19:2
-    }
-}
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index f09f7621aa170..21fb7673ce061 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -3135,14 +3135,47 @@ impl<'test> TestCx<'test> {
         }
         for l in test_file_contents.lines() {
             if l.starts_with("// EMIT_MIR ") {
-                let test_name = l.trim_start_matches("// EMIT_MIR ");
-                let expected_file = test_dir.join(test_name);
-
-                let dumped_string = if test_name.ends_with(".diff") {
-                    let test_name = test_name.trim_end_matches(".diff");
-                    let before = format!("{}.before.mir", test_name);
-                    let after = format!("{}.after.mir", test_name);
-                    let before = self.get_mir_dump_dir().join(before);
+                let test_name = l.trim_start_matches("// EMIT_MIR ").trim();
+                let mut test_names = test_name.split(' ');
+                // sometimes we specify two files so that we get a diff between the two files
+                let test_name = test_names.next().unwrap();
+                let expected_file;
+                let from_file;
+                let to_file;
+
+                if test_name.ends_with(".diff") {
+                    let trimmed = test_name.trim_end_matches(".diff");
+                    let test_against = format!("{}.after.mir", trimmed);
+                    from_file = format!("{}.before.mir", trimmed);
+                    expected_file = test_name.to_string();
+                    assert!(
+                        test_names.next().is_none(),
+                        "two mir pass names specified for MIR diff"
+                    );
+                    to_file = Some(test_against);
+                } else if let Some(first_pass) = test_names.next() {
+                    let second_pass = test_names.next().unwrap();
+                    assert!(
+                        test_names.next().is_none(),
+                        "three mir pass names specified for MIR diff"
+                    );
+                    expected_file = format!("{}.{}-{}.diff", test_name, first_pass, second_pass);
+                    let second_file = format!("{}.{}.mir", test_name, second_pass);
+                    from_file = format!("{}.{}.mir", test_name, first_pass);
+                    to_file = Some(second_file);
+                } else {
+                    expected_file = test_name.to_string();
+                    from_file = test_name.to_string();
+                    assert!(
+                        test_names.next().is_none(),
+                        "two mir pass names specified for MIR dump"
+                    );
+                    to_file = None;
+                };
+                let expected_file = test_dir.join(expected_file);
+
+                let dumped_string = if let Some(after) = to_file {
+                    let before = self.get_mir_dump_dir().join(from_file);
                     let after = self.get_mir_dump_dir().join(after);
                     debug!(
                         "comparing the contents of: {} with {}",
@@ -3166,7 +3199,7 @@ impl<'test> TestCx<'test> {
                 } else {
                     let mut output_file = PathBuf::new();
                     output_file.push(self.get_mir_dump_dir());
-                    output_file.push(test_name);
+                    output_file.push(&from_file);
                     debug!(
                         "comparing the contents of: {} with {}",
                         output_file.display(),
@@ -3179,7 +3212,7 @@ impl<'test> TestCx<'test> {
                             output_file.parent().unwrap().display()
                         );
                     }
-                    self.check_mir_test_timestamp(test_name, &output_file);
+                    self.check_mir_test_timestamp(&from_file, &output_file);
                     let dumped_string = fs::read_to_string(&output_file).unwrap();
                     self.normalize_output(&dumped_string, &[])
                 };