Rollup merge of #96090 - JakobDegen:mir-tests, r=nagisa

Implement MIR opt unit tests

This implements rust-lang/compiler-team#502 .

There's not much to say here, this implementation does everything as proposed. I also added the flag to a bunch of existing tests (mostly those to which I could add it without causing huge diffs due to changes in line numbers). Summarizing the changes to test outputs:
 - Every time an `MirPatch` is created, it adds a cleanup block to the body if it did not exist already. If this block is unused (as is usually the case), it usually gets removed soon after by some pass calling `SimplifyCFG` for unrelated reasons (in many cases this cycle happens quite a few times for a single body). We now run `SimplifyCFG` less often, so those blocks end up in some of our outputs. I looked at changing `MirPatch` to not do this, but that seemed too complicated for this PR. I may still do that in a follow-up.
 - The `InstCombine` test had set `-C opt-level=0` in its flags and so there were no storage markers. I don't really see a good motivation for doing this, so bringing it back in line with what everything else does seems correct.
 - One of the `EarlyOtherwiseBranch` tests had `UnreachableProp` running on it. Preventing that kind of thing is the goal of this feature, so this seems fine.

For the remaining tests for which this feature might be useful, we can gradually migrate them as opportunities present themselves.

In terms of documentation, I plan on submitting a PR to the rustc dev guide in the near future documenting this and other recent changes to MIR. If there's any other places to update, do let me know

r? `@nagisa`

compiler/rustc_interface/src/tests.rs

@@ -752,6 +752,7 @@ fn test_debugging_options_tracking_hash() {
     tracked!(location_detail, LocationDetail { file: true, line: false, column: false });
     tracked!(merge_functions, Some(MergeFunctions::Disabled));
     tracked!(mir_emit_retag, true);
+    tracked!(mir_enable_passes, vec![("DestProp".to_string(), false)]);
     tracked!(mir_opt_level, Some(4));
     tracked!(move_size_limit, Some(4096));
     tracked!(mutable_noalias, Some(true));

compiler/rustc_mir_transform/src/pass_manager.rs

@@ -77,17 +77,30 @@ pub fn run_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, passes: &[&dyn
     let mut cnt = 0;
 
     let validate = tcx.sess.opts.debugging_opts.validate_mir;
+    let overridden_passes = &tcx.sess.opts.debugging_opts.mir_enable_passes;
+    trace!(?overridden_passes);
 
     if validate {
         validate_body(tcx, body, format!("start of phase transition from {:?}", start_phase));
     }
 
     for pass in passes {
-        if !pass.is_enabled(&tcx.sess) {
-            continue;
-        }
-
         let name = pass.name();
+
+        if let Some((_, polarity)) = overridden_passes.iter().rev().find(|(s, _)| s == &*name) {
+            trace!(
+                pass = %name,
+                "{} as requested by flag",
+                if *polarity { "Running" } else { "Not running" },
+            );
+            if !polarity {
+                continue;
+            }
+        } else {
+            if !pass.is_enabled(&tcx.sess) {
+                continue;
+            }
+        }
         let dump_enabled = pass.is_mir_dump_enabled();
 
         if dump_enabled {

compiler/rustc_session/src/options.rs

@@ -368,6 +368,8 @@ mod desc {
     pub const parse_opt_langid: &str = "a language identifier";
     pub const parse_opt_pathbuf: &str = "a path";
     pub const parse_list: &str = "a space-separated list of strings";
+    pub const parse_list_with_polarity: &str =
+        "a comma-separated list of strings, with elements beginning with + or -";
     pub const parse_opt_comma_list: &str = "a comma-separated list of strings";
     pub const parse_number: &str = "a number";
     pub const parse_opt_number: &str = parse_number;
@@ -529,6 +531,19 @@ mod parse {
         }
     }
 
+    crate fn parse_list_with_polarity(slot: &mut Vec<(String, bool)>, v: Option<&str>) -> bool {
+        match v {
+            Some(s) => {
+                for s in s.split(",") {
+                    let Some(pass_name) = s.strip_prefix(&['+', '-'][..]) else { return false };
+                    slot.push((pass_name.to_string(), &s[..1] == "+"));
+                }
+                true
+            }
+            None => false,
+        }
+    }
+
     crate fn parse_location_detail(ld: &mut LocationDetail, v: Option<&str>) -> bool {
         if let Some(v) = v {
             ld.line = false;
@@ -1318,6 +1333,10 @@ options! {
     mir_emit_retag: bool = (false, parse_bool, [TRACKED],
         "emit Retagging MIR statements, interpreted e.g., by miri; implies -Zmir-opt-level=0 \
         (default: no)"),
+    mir_enable_passes: Vec<(String, bool)> = (Vec::new(), parse_list_with_polarity, [TRACKED],
+        "use like `-Zmir-enable-passes=+DestProp,-InstCombine`. Forces the specified passes to be \
+        enabled, overriding all other checks. Passes that are not specified are enabled or \
+        disabled by other flags as usual."),
     mir_opt_level: Option<usize> = (None, parse_opt_number, [TRACKED],
         "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
     move_size_limit: Option<usize> = (None, parse_opt_number, [TRACKED],

src/test/mir-opt/combine_clone_of_primitives.rs

@@ -1,4 +1,4 @@
-// compile-flags: -C opt-level=0 -Z inline_mir=no
+// unit-test: InstCombine
 // ignore-wasm32 compiled with panic=abort by default
 
 // EMIT_MIR combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff

src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff

@@ -23,9 +23,15 @@
       }
   
       bb0: {
+          StorageLive(_2);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
           _2 = &((*_1).0: T);              // scope 0 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
+          StorageLive(_3);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
           _3 = &((*_1).1: u64);            // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
+          StorageLive(_4);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
           _4 = &((*_1).2: [f32; 3]);       // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
+          StorageLive(_5);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
+          StorageLive(_6);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
+          StorageLive(_7);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
 -         _7 = &(*_2);                     // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
 -         _6 = &(*_7);                     // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
 +         _7 = _2;                         // scope 1 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
@@ -37,6 +43,10 @@
       }
   
       bb1: {
+          StorageDead(_6);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:8:8: 8:9
+          StorageLive(_8);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
+          StorageLive(_9);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
+          StorageLive(_10);                // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 -         _10 = &(*_3);                    // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 -         _9 = &(*_10);                    // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 -         _8 = <u64 as Clone>::clone(move _9) -> [return: bb2, unwind: bb4]; // scope 1 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
@@ -50,6 +60,10 @@
       }
   
       bb2: {
+          StorageDead(_9);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:9:10: 9:11
+          StorageLive(_11);                // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
+          StorageLive(_12);                // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
+          StorageLive(_13);                // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 -         _13 = &(*_4);                    // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 -         _12 = &(*_13);                   // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 -         _11 = <[f32; 3] as Clone>::clone(move _12) -> [return: bb3, unwind: bb4]; // scope 1 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
@@ -63,10 +77,20 @@
       }
   
       bb3: {
+          StorageDead(_12);                // scope 1 at $DIR/combine_clone_of_primitives.rs:10:15: 10:16
           Deinit(_0);                      // scope 1 at $DIR/combine_clone_of_primitives.rs:6:10: 6:15
           (_0.0: T) = move _5;             // scope 1 at $DIR/combine_clone_of_primitives.rs:6:10: 6:15
           (_0.1: u64) = move _8;           // scope 1 at $DIR/combine_clone_of_primitives.rs:6:10: 6:15
           (_0.2: [f32; 3]) = move _11;     // scope 1 at $DIR/combine_clone_of_primitives.rs:6:10: 6:15
+          StorageDead(_13);                // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_11);                // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_10);                // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_8);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_7);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_5);                 // scope 1 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_4);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_3);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
+          StorageDead(_2);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:6:14: 6:15
           return;                          // scope 0 at $DIR/combine_clone_of_primitives.rs:6:15: 6:15
       }
   

src/test/mir-opt/early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff

@@ -68,8 +68,10 @@
 +     bb3: {
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/early_otherwise_branch.rs:8:2: 8:2
-+     }
-+ 
+      }
+  
+-     bb5 (cleanup): {
+-         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:3:1: 8:2
 +     bb4: {
 +         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

src/test/mir-opt/early_otherwise_branch.opt2.EarlyOtherwiseBranch.diff

@@ -32,7 +32,7 @@
           StorageDead(_5);                 // scope 0 at $DIR/early_otherwise_branch.rs:12:16: 12:17
           StorageDead(_4);                 // scope 0 at $DIR/early_otherwise_branch.rs:12:16: 12:17
           _8 = discriminant((_3.0: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch.rs:12:11: 12:17
--         switchInt(move _8) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb7]; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
+-         switchInt(move _8) -> [0_isize: bb1, 1_isize: bb3, otherwise: bb2]; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
 +         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
@@ -84,8 +84,8 @@
           return;                          // scope 0 at $DIR/early_otherwise_branch.rs:17:2: 17:2
       }
   
--     bb7: {
--         unreachable;                     // scope 0 at $DIR/early_otherwise_branch.rs:15:14: 15:15
+-     bb7 (cleanup): {
+-         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:11:1: 17:2
 +     bb5: {
 +         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

src/test/mir-opt/early_otherwise_branch.opt3.EarlyOtherwiseBranch.diff

@@ -68,8 +68,10 @@
 +     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
-+     }
-+ 
+      }
+  
+-     bb5 (cleanup): {
+-         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:21:1: 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

src/test/mir-opt/early_otherwise_branch.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
+// unit-test: EarlyOtherwiseBranch
 // EMIT_MIR early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>) -> u32 {
     match (x, y) {

src/test/mir-opt/early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff

@@ -90,8 +90,10 @@
 +     bb4: {
           StorageDead(_4);                 // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:9:2: 9:2
-+     }
-+ 
+      }
+  
+-     bb6 (cleanup): {
+-         resume;                          // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:4:1: 9:2
 +     bb5: {
 +         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

src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
+// unit-test: EarlyOtherwiseBranch
 
 // EMIT_MIR early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>, z: Option<u32>) -> u32 {

src/test/mir-opt/early_otherwise_branch_noopt.noopt1.EarlyOtherwiseBranch.diff

@@ -38,25 +38,29 @@
           StorageDead(_5);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:16: 8:17
           StorageDead(_4);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:16: 8:17
           _8 = discriminant((_3.0: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:11: 8:17
-          switchInt(move _8) -> [0_isize: bb1, otherwise: bb3]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
+          switchInt(move _8) -> [0_isize: bb1, 1_isize: bb4, otherwise: bb3]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
       }
   
       bb1: {
           _6 = discriminant((_3.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:11: 8:17
-          switchInt(move _6) -> [0_isize: bb2, otherwise: bb6]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
+          switchInt(move _6) -> [0_isize: bb2, 1_isize: bb7, otherwise: bb3]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
       }
   
       bb2: {
           _0 = const 3_u32;                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:12:25: 12:26
-          goto -> bb7;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:12:25: 12:26
+          goto -> bb8;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:12:25: 12:26
       }
   
       bb3: {
-          _7 = discriminant((_3.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:11: 8:17
-          switchInt(move _7) -> [0_isize: bb5, otherwise: bb4]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
+          unreachable;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:11: 8:17
       }
   
       bb4: {
+          _7 = discriminant((_3.1: std::option::Option<u32>)); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:11: 8:17
+          switchInt(move _7) -> [0_isize: bb6, 1_isize: bb5, otherwise: bb3]; // scope 0 at $DIR/early_otherwise_branch_noopt.rs:8:5: 8:17
+      }
+  
+      bb5: {
           StorageLive(_9);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:15: 9:16
           _9 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:15: 9:16
           StorageLive(_10);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:24: 9:25
@@ -64,28 +68,32 @@
           _0 = const 0_u32;                // scope 1 at $DIR/early_otherwise_branch_noopt.rs:9:31: 9:32
           StorageDead(_10);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:31: 9:32
           StorageDead(_9);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:31: 9:32
-          goto -> bb7;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:31: 9:32
+          goto -> bb8;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:9:31: 9:32
       }
   
-      bb5: {
+      bb6: {
           StorageLive(_11);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:10:15: 10:16
           _11 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:10:15: 10:16
           _0 = const 1_u32;                // scope 2 at $DIR/early_otherwise_branch_noopt.rs:10:28: 10:29
           StorageDead(_11);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:10:28: 10:29
-          goto -> bb7;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:10:28: 10:29
+          goto -> bb8;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:10:28: 10:29
       }
   
-      bb6: {
+      bb7: {
           StorageLive(_12);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:11:21: 11:22
           _12 = (((_3.1: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_noopt.rs:11:21: 11:22
           _0 = const 2_u32;                // scope 3 at $DIR/early_otherwise_branch_noopt.rs:11:28: 11:29
           StorageDead(_12);                // scope 0 at $DIR/early_otherwise_branch_noopt.rs:11:28: 11:29
-          goto -> bb7;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:11:28: 11:29
+          goto -> bb8;                     // scope 0 at $DIR/early_otherwise_branch_noopt.rs:11:28: 11:29
       }
   
-      bb7: {
+      bb8: {
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:14:1: 14:2
           return;                          // scope 0 at $DIR/early_otherwise_branch_noopt.rs:14:2: 14:2
       }
+  
+      bb9 (cleanup): {
+          resume;                          // scope 0 at $DIR/early_otherwise_branch_noopt.rs:7:1: 14:2
+      }
   }
   

src/test/mir-opt/early_otherwise_branch_noopt.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4 -Zunsound-mir-opts
+// unit-test: EarlyOtherwiseBranch
 
 // must not optimize as it does not follow the pattern of
 // left and right hand side being the same variant

src/test/mir-opt/early_otherwise_branch_soundness.no_deref_ptr.EarlyOtherwiseBranch.diff

@@ -19,7 +19,7 @@
   
       bb1: {
           _0 = const 0_i32;                // scope 0 at $DIR/early_otherwise_branch_soundness.rs:25:14: 25:15
-          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:25:14: 25:15
+          goto -> bb5;                     // scope 0 at $DIR/early_otherwise_branch_soundness.rs:25:14: 25:15
       }
   
       bb2: {
@@ -29,7 +29,7 @@
   
       bb3: {
           _0 = const 0_i32;                // scope 0 at $DIR/early_otherwise_branch_soundness.rs:23:18: 23:19
-          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:23:18: 23:19
+          goto -> bb5;                     // scope 0 at $DIR/early_otherwise_branch_soundness.rs:23:18: 23:19
       }
   
       bb4: {
@@ -37,7 +37,15 @@
           _5 = (((*_2) as Some).0: i32);   // scope 0 at $DIR/early_otherwise_branch_soundness.rs:22:18: 22:19
           _0 = _5;                         // scope 1 at $DIR/early_otherwise_branch_soundness.rs:22:24: 22:25
           StorageDead(_5);                 // scope 0 at $DIR/early_otherwise_branch_soundness.rs:22:24: 22:25
-          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:22:24: 22:25
+          goto -> bb5;                     // scope 0 at $DIR/early_otherwise_branch_soundness.rs:22:24: 22:25
+      }
+  
+      bb5: {
+          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:27:2: 27:2
+      }
+  
+      bb6 (cleanup): {
+          resume;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:18:1: 27:2
       }
   }
   

src/test/mir-opt/early_otherwise_branch_soundness.no_downcast.EarlyOtherwiseBranch.diff

@@ -19,12 +19,20 @@
   
       bb2: {
           _0 = const 1_u32;                // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:38: 13:39
-          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:5: 13:52
+          goto -> bb4;                     // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:5: 13:52
       }
   
       bb3: {
           _0 = const 2_u32;                // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:49: 13:50
-          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:5: 13:52
+          goto -> bb4;                     // scope 0 at $DIR/early_otherwise_branch_soundness.rs:13:5: 13:52
+      }
+  
+      bb4: {
+          return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:14:2: 14:2
+      }
+  
+      bb5 (cleanup): {
+          resume;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:12:1: 14:2
       }
   }
   

src/test/mir-opt/early_otherwise_branch_soundness.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4 -Zunsound-mir-opts
+// unit-test: EarlyOtherwiseBranch
 
 // Tests various cases that the `early_otherwise_branch` opt should *not* optimize
 

src/test/mir-opt/if-condition-int.rs

@@ -1,4 +1,4 @@
-// compile-flags: -O
+// unit-test: SimplifyComparisonIntegral
 // EMIT_MIR if_condition_int.opt_u32.SimplifyComparisonIntegral.diff
 // EMIT_MIR if_condition_int.opt_negative.SimplifyComparisonIntegral.diff
 // EMIT_MIR if_condition_int.opt_char.SimplifyComparisonIntegral.diff

src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff

@@ -26,5 +26,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:17:25: 17:26
           return;                          // scope 0 at $DIR/if-condition-int.rs:18:2: 18:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:16:1: 18:2
+      }
   }
   

src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff

@@ -30,5 +30,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:53:34: 53:35
           return;                          // scope 0 at $DIR/if-condition-int.rs:54:2: 54:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:52:1: 54:2
+      }
   }
   

src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff

@@ -54,5 +54,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:49:1: 49:2
           return;                          // scope 0 at $DIR/if-condition-int.rs:49:2: 49:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:43:1: 49:2
+      }
   }
   

src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff

@@ -35,5 +35,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:21:32: 21:33
           return;                          // scope 0 at $DIR/if-condition-int.rs:22:2: 22:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:20:1: 22:2
+      }
   }
   

src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff

@@ -35,5 +35,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:25:31: 25:32
           return;                          // scope 0 at $DIR/if-condition-int.rs:26:2: 26:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:24:1: 26:2
+      }
   }
   

src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff

@@ -61,5 +61,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:39:5: 39:6
           return;                          // scope 0 at $DIR/if-condition-int.rs:40:2: 40:2
       }
+  
+      bb7 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:32:1: 40:2
+      }
   }
   

src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff

@@ -35,5 +35,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:29:32: 29:33
           return;                          // scope 0 at $DIR/if-condition-int.rs:30:2: 30:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:28:1: 30:2
+      }
   }
   

src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff

@@ -35,5 +35,9 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:12:31: 12:32
           return;                          // scope 0 at $DIR/if-condition-int.rs:13:2: 13:2
       }
+  
+      bb4 (cleanup): {
+          resume;                          // scope 0 at $DIR/if-condition-int.rs:11:1: 13:2
+      }
   }
   

src/test/mir-opt/lower_slice_len.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=3
+// unit-test: LowerSliceLenCalls
 
 // EMIT_MIR lower_slice_len.bound.LowerSliceLenCalls.diff
 pub fn bound(index: usize, slice: &[u8]) -> u8 {

src/test/mir-opt/nrvo-simple.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Zmir-opt-level=1
+// unit-test: RenameReturnPlace
 
 // EMIT_MIR nrvo_simple.nrvo.RenameReturnPlace.diff
 fn nrvo(init: fn(&mut [u8; 1024])) -> [u8; 1024] {

src/test/mir-opt/nrvo_simple.nrvo.RenameReturnPlace.diff

@@ -39,5 +39,9 @@
 -         StorageDead(_2);                 // scope 0 at $DIR/nrvo-simple.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/nrvo-simple.rs:8:2: 8:2
       }
+  
+      bb2 (cleanup): {
+          resume;                          // scope 0 at $DIR/nrvo-simple.rs:4:1: 8:2
+      }
   }
   

src/tools/compiletest/src/header.rs

@@ -157,6 +157,8 @@ pub struct TestProps {
     pub should_ice: bool,
     // If true, the stderr is expected to be different across bit-widths.
     pub stderr_per_bitwidth: bool,
+    // The MIR opt to unit test, if any
+    pub mir_unit_test: Option<String>,
 }
 
 mod directives {
@@ -189,6 +191,7 @@ mod directives {
     pub const STDERR_PER_BITWIDTH: &'static str = "stderr-per-bitwidth";
     pub const INCREMENTAL: &'static str = "incremental";
     pub const KNOWN_BUG: &'static str = "known-bug";
+    pub const MIR_UNIT_TEST: &'static str = "unit-test";
     // This isn't a real directive, just one that is probably mistyped often
     pub const INCORRECT_COMPILER_FLAGS: &'static str = "compiler-flags";
 }
@@ -232,6 +235,7 @@ impl TestProps {
             assembly_output: None,
             should_ice: false,
             stderr_per_bitwidth: false,
+            mir_unit_test: None,
         }
     }
 
@@ -392,6 +396,9 @@ impl TestProps {
                 config.set_name_directive(ln, STDERR_PER_BITWIDTH, &mut self.stderr_per_bitwidth);
                 config.set_name_directive(ln, INCREMENTAL, &mut self.incremental);
                 config.set_name_directive(ln, KNOWN_BUG, &mut self.known_bug);
+                config.set_name_value_directive(ln, MIR_UNIT_TEST, &mut self.mir_unit_test, |s| {
+                    s.trim().to_string()
+                });
             });
         }
 

src/tools/compiletest/src/runtest.rs

@@ -1856,10 +1856,14 @@ impl<'test> TestCx<'test> {
                 rustc.args(&[
                     "-Copt-level=1",
                     "-Zdump-mir=all",
-                    "-Zmir-opt-level=4",
                     "-Zvalidate-mir",
                     "-Zdump-mir-exclude-pass-number",
                 ]);
+                if let Some(pass) = &self.props.mir_unit_test {
+                    rustc.args(&["-Zmir-opt-level=0", &format!("-Zmir-enable-passes=+{}", pass)]);
+                } else {
+                    rustc.arg("-Zmir-opt-level=4");
+                }
 
                 let mir_dump_dir = self.get_mir_dump_dir();
                 let _ = fs::remove_dir_all(&mir_dump_dir);