Auto merge of #45162 - chrisvittal:mir-testing, r=nikomatsakis

 Modify MIR testing to require consecutive lines

MIR testing now requires that lines be consecutive. To achive this,
instead of collecting the expected mir as a string, it is now wrapped in
an `ExpectedLine` enum, that is either `Elision` or `Text(T)` where `T:
AsRef<str>`. `Text` lines must be matched in order, unless separated by
`Elision` lines. Elision occurs lazily, that is, an Elision will skip
as few lines as possible.

To add a new elision marker. Put a comment containing only "..." and
whitespace in any MIR testing block. Like so:

```
// fn write_42(_1: *mut i32) -> bool {
//     ...
//     bb0: {
//         Validate(Acquire, [_1: *mut i32]);
//         Validate(Release, [_1: *mut i32]);
//         ...
//         return;
//     }
// }
```

Right now, all input before the line right after `// START` is elided,
and all input after the line right before `// END` is also not tested.

Many tests need to be updated. That will follow in the next commit.

cc #45153
r? @nikomatsakis

src/test/mir-opt/README.md

@@ -7,13 +7,13 @@ The test format is:
 // END RUST SOURCE
 // START $file_name_of_some_mir_dump_0
 //  $expected_line_0
-// ...
+// (lines or elision)
 // $expected_line_N
 // END $file_name_of_some_mir_dump_0
-// ...
+// (lines or elision)
 // START $file_name_of_some_mir_dump_N
 //  $expected_line_0
-// ...
+// (lines or elision)
 // $expected_line_N
 // END $file_name_of_some_mir_dump_N
 ```
@@ -22,10 +22,15 @@ All the test information is in comments so the test is runnable.
 
 For each $file_name, compiletest expects [$expected_line_0, ...,
 $expected_line_N] to appear in the dumped MIR in order.  Currently it allows
-other non-matched lines before, after and in-between. Note that this includes
-lines that end basic blocks or begin new ones; it is good practice
-in your tests to include the terminator for each of your basic blocks as an
-internal sanity check guarding against a test like:
+other non-matched lines before and after, but not between $expected_lines,
+should you want to skip lines, you must include an elision comment, of the form
+(as a regex) `//\s*...\s*`. The lines will be skipped lazily, that is, if there
+are two identical lines in the output that match the line after the elision
+comment, the first one wil be matched.
+
+Examples:
+
+The following blocks will not match the one after it.
 
 ```
 bb0: {
@@ -35,8 +40,6 @@ bb0: {
 }
 ```
 
-that will inadvertantly pattern-matching against:
-
 ```
 bb0: {
     StorageLive(_1);
@@ -49,6 +52,18 @@ bb1: {
 }
 ```
 
+But this will match the one above,
+
+```
+bb0: {
+    StorageLive(_1);
+    _1 = const true;
+    ...
+    StorageDead(_1);
+    ...
+}
+```
+
 Lines match ignoring whitespace, and the prefix "//" is removed.
 
 It also currently strips trailing comments -- partly because the full file path

src/test/mir-opt/box_expr.rs

@@ -30,7 +30,10 @@ impl Drop for S {
 // END RUST SOURCE
 // START rustc.node4.ElaborateDrops.before.mir
 //     let mut _0: ();
-//     let _1: std::boxed::Box<S>;
+//     scope 1 {
+//         let _1: std::boxed::Box<S>;
+//     }
+//     ...
 //     let mut _2: std::boxed::Box<S>;
 //     let mut _3: ();
 //     let mut _4: std::boxed::Box<S>;

src/test/mir-opt/copy_propagation.rs

@@ -18,17 +18,23 @@ fn main() { }
 // END RUST SOURCE
 // START rustc.node4.CopyPropagation.before.mir
 //  bb0: {
+//      ...
 //      _2 = _1;
+//      ...
 //      _4 = _2;
 //      _3 = _4;
+//      ...
 //      _5 = _3;
 //      _0 = _5;
+//      ...
 //      return;
 //  }
 // END rustc.node4.CopyPropagation.before.mir
 // START rustc.node4.CopyPropagation.after.mir
 //  bb0: {
+//      ...
 //      _0 = _1;
+//      ...
 //      return;
 //  }
 // END rustc.node4.CopyPropagation.after.mir

src/test/mir-opt/deaggregator_test.rs

@@ -23,19 +23,25 @@ fn main() {}
 // END RUST SOURCE
 // START rustc.node13.Deaggregator.before.mir
 // bb0: {
+//     ...
 //     _2 = _1;
+//     ...
 //     _3 = _2;
 //     _0 = Baz { x: _3, y: const 0f32, z: const false };
+//     ...
 //     return;
 // }
 // END rustc.node13.Deaggregator.before.mir
 // START rustc.node13.Deaggregator.after.mir
 // bb0: {
+//     ...
 //     _2 = _1;
+//     ...
 //     _3 = _2;
 //     (_0.0: usize) = _3;
 //     (_0.1: f32) = const 0f32;
 //     (_0.2: bool) = const false;
+//     ...
 //     return;
 // }
 // END rustc.node13.Deaggregator.after.mir

src/test/mir-opt/deaggregator_test_enum.rs

@@ -28,18 +28,26 @@ fn main() {
 // END RUST SOURCE
 // START rustc.node10.Deaggregator.before.mir
 // bb0: {
+//     StorageLive(_2);
 //     _2 = _1;
+//     StorageLive(_3);
 //     _3 = _2;
 //     _0 = Baz::Foo { x: _3 };
+//     StorageDead(_3);
+//     StorageDead(_2);
 //     return;
 // }
 // END rustc.node10.Deaggregator.before.mir
 // START rustc.node10.Deaggregator.after.mir
 // bb0: {
+//     StorageLive(_2);
 //     _2 = _1;
+//     StorageLive(_3);
 //     _3 = _2;
 //     ((_0 as Foo).0: usize) = _3;
 //     discriminant(_0) = 1;
+//     StorageDead(_3);
+//     StorageDead(_2);
 //     return;
 // }
 // END rustc.node10.Deaggregator.after.mir

src/test/mir-opt/deaggregator_test_enum_2.rs

@@ -28,29 +28,35 @@ fn main() {}
 // END RUST SOURCE
 // START rustc.node12.Deaggregator.before.mir
 //  bb1: {
+//      StorageLive(_6);
 //      _6 = _4;
 //      _0 = Foo::A(_6,);
+//      StorageDead(_6);
 //      goto -> bb3;
 //  }
-//
 //  bb2: {
+//      StorageLive(_7);
 //      _7 = _4;
 //      _0 = Foo::B(_7,);
+//      StorageDead(_7);
 //      goto -> bb3;
 //  }
 // END rustc.node12.Deaggregator.before.mir
 // START rustc.node12.Deaggregator.after.mir
 //  bb1: {
+//      StorageLive(_6);
 //      _6 = _4;
 //      ((_0 as A).0: i32) = _6;
 //      discriminant(_0) = 0;
+//      StorageDead(_6);
 //      goto -> bb3;
 //  }
-//
 //  bb2: {
+//      StorageLive(_7);
 //      _7 = _4;
 //      ((_0 as B).0: i32) = _7;
 //      discriminant(_0) = 1;
+//      StorageDead(_7);
 //      goto -> bb3;
 //  }
 // END rustc.node12.Deaggregator.after.mir

src/test/mir-opt/deaggregator_test_multiple.rs

@@ -24,25 +24,35 @@ fn main() { }
 // END RUST SOURCE
 // START rustc.node10.Deaggregator.before.mir
 // bb0: {
+//     ...
 //     _2 = _1;
+//     ...
 //     _4 = _2;
 //     _3 = Foo::A(_4,);
+//     ...
 //     _6 = _2;
 //     _5 = Foo::A(_6,);
+//     ...
 //     _0 = [_3, _5];
+//     ...
 //     return;
 // }
 // END rustc.node10.Deaggregator.before.mir
 // START rustc.node10.Deaggregator.after.mir
 // bb0: {
+//     ...
 //     _2 = _1;
+//     ...
 //     _4 = _2;
 //     ((_3 as A).0: i32) = _4;
 //     discriminant(_3) = 0;
+//     ...
 //     _6 = _2;
 //     ((_5 as A).0: i32) = _6;
 //     discriminant(_5) = 0;
+//     ...
 //     _0 = [_3, _5];
+//     ...
 //     return;
 // }
 // END rustc.node10.Deaggregator.after.mir

src/test/mir-opt/end_region_1.rs

@@ -21,9 +21,11 @@ fn main() {
 // END RUST SOURCE
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 //     let mut _0: ();
+//     ...
 //     let _1: i32;
+//     ...
 //     let _2: &'10_1rs i32;
-//
+//     ...
 //     bb0: {
 //         StorageLive(_1);
 //         _1 = const 3i32;

src/test/mir-opt/end_region_2.rs

@@ -26,11 +26,16 @@ fn main() {
 // END RUST SOURCE
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 //     let mut _0: ();
+//     ...
 //     let _2: bool;
+//     ...
 //     let _3: &'23_1rs bool;
+//     ...
 //     let _7: &'23_3rs bool;
+//     ...
 //     let mut _4: ();
 //     let mut _5: bool;
+//     ...
 //     bb0: {
 //         goto -> bb1;
 //     }
@@ -52,6 +57,7 @@ fn main() {
 //         return;
 //     }
 //     bb3: {
+//         _4 = ();
 //         StorageDead(_5);
 //         StorageLive(_7);
 //         _7 = &'23_3rs _2;

src/test/mir-opt/end_region_3.rs

@@ -27,13 +27,17 @@ fn main() {
 // END RUST SOURCE
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 //     let mut _0: ();
+//     ...
 //     let mut _1: bool;
+//     ...
 //     let _3: &'26_1rs bool;
+//     ...
 //     let _7: &'26_3rs bool;
+//     ...
 //     let mut _2: ();
 //     let mut _4: ();
 //     let mut _5: bool;
-//
+//     let mut _6: !;
 //     bb0: {
 //         StorageLive(_1);
 //         goto -> bb1;

src/test/mir-opt/end_region_4.rs

@@ -31,10 +31,15 @@ fn foo(i: i32) {
 // END RUST SOURCE
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 //     let mut _0: ();
+//     ...
 //     let _1: D;
+//     ...
 //     let _2: i32;
+//     ...
 //     let _3: &'26_2rs i32;
+//     ...
 //     let _6: &'26_4rs i32;
+//     ...
 //     let mut _4: ();
 //     let mut _5: i32;
 //     bb0: {

src/test/mir-opt/end_region_5.rs

@@ -28,8 +28,11 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // END RUST SOURCE
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 // fn main() -> () {
+//     ...
 //     let mut _0: ();
+//     ...
 //     let _1: D;
+//     ...
 //     let mut _2: ();
 //     let mut _3: [closure@NodeId(18) d:&'14s D];
 //     let mut _4: &'14s D;

src/test/mir-opt/end_region_6.rs

@@ -29,7 +29,9 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 // fn main() -> () {
 //     let mut _0: ();
+//     ...
 //     let _1: D;
+//     ...
 //     let mut _2: ();
 //     let mut _3: [closure@NodeId(22) d:&'19s D];
 //     let mut _4: &'19s D;
@@ -65,9 +67,10 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // START rustc.node22.SimplifyCfg-qualify-consts.after.mir
 // fn main::{{closure}}(_1: [closure@NodeId(22) d:&'19s D]) -> i32 {
 //     let mut _0: i32;
+//     ...
 //     let _2: &'15_0rs D;
+//     ...
 //     let mut _3: i32;
-//
 //     bb0: {
 //         StorageLive(_2);
 //         _2 = &'15_0rs (*(_1.0: &'19s D));

src/test/mir-opt/end_region_7.rs

@@ -29,11 +29,12 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 // fn main() -> () {
 //     let mut _0: ();
+//     ...
 //     let _1: D;
+//     ...
 //     let mut _2: ();
 //     let mut _3: [closure@NodeId(22) d:D];
 //     let mut _4: D;
-//
 //     bb0: {
 //         StorageLive(_1);
 //         _1 = D::{{constructor}}(const 0i32,);
@@ -74,9 +75,10 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // START rustc.node22.SimplifyCfg-qualify-consts.after.mir
 // fn main::{{closure}}(_1: [closure@NodeId(22) d:D]) -> i32 {
 //     let mut _0: i32;
+//     ...
 //     let _2: &'15_0rs D;
+//     ...
 //     let mut _3: i32;
-//
 //     bb0: {
 //         StorageLive(_2);
 //         _2 = &'15_0rs (_1.0: D);

src/test/mir-opt/end_region_8.rs

@@ -30,8 +30,11 @@ fn foo<F>(f: F) where F: FnOnce() -> i32 {
 // START rustc.node4.SimplifyCfg-qualify-consts.after.mir
 // fn main() -> () {
 //    let mut _0: ();
+//    ...
 //    let _1: D;
+//    ...
 //    let _2: &'21_1rs D;
+//    ...
 //    let mut _3: ();
 //    let mut _4: [closure@NodeId(22) r:&'21_1rs D];
 //    let mut _5: &'21_1rs D;