Rollup merge of rust-lang#100086 - JakobDegen:better-tests, r=wesleyweiser

Add more `// unit-test`s to MIR opt tests

I only changed things which are hopefully completely uninteresting. I plan to submit more PRs that cover more files, but those cases will need some more complicated (and hence possibly controversial) changes, so I'll try and submit those in reasonably sized batches.

r? rust-lang/wg-mir-opt

Author: matthiaskrgr

src/test/mir-opt/bool_compare.rs

@@ -1,3 +1,5 @@
+// unit-test: InstCombine
+
 // EMIT_MIR bool_compare.opt1.InstCombine.diff
 fn opt1(x: bool) -> u32 {
     if x != true { 0 } else { 1 }

src/test/mir-opt/combine_array_len.norm2.InstCombine.64bit.diff

@@ -1,4 +1,4 @@
-// EMIT_MIR_FOR_EACH_BIT_WIDTH
+// unit-test: InstCombine
 // EMIT_MIR combine_array_len.norm2.InstCombine.diff
 
 fn norm2(x: [f32; 2]) -> f32 {

src/test/mir-opt/combine_array_len.norm2.InstCombine.32bit.diff renamed to src/test/mir-opt/combine_array_len.norm2.InstCombine.diff

@@ -1,3 +1,5 @@
+// unit-test: ConstGoto
+
 pub enum Foo {
     A,
     B,

src/test/mir-opt/combine_array_len.rs

@@ -17,7 +17,7 @@
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/const_goto_storage.rs:+1:9: +1:12
 -         StorageLive(_2);                 // scope 0 at $DIR/const_goto_storage.rs:+1:21: +1:23
--         nop;                             // scope 0 at $DIR/const_goto_storage.rs:+1:21: +1:23
+-         Deinit(_2);                      // scope 0 at $DIR/const_goto_storage.rs:+1:21: +1:23
 -         StorageLive(_3);                 // scope 0 at $DIR/const_goto_storage.rs:+2:15: +6:10
 -         StorageLive(_4);                 // scope 0 at $DIR/const_goto_storage.rs:+2:18: +2:76
 -         StorageLive(_5);                 // scope 0 at $DIR/const_goto_storage.rs:+2:21: +2:52

src/test/mir-opt/const_goto.rs

@@ -1,3 +1,5 @@
+// unit-test: ConstGoto
+
 // EMIT_MIR const_goto_storage.match_nested_if.ConstGoto.diff
 fn match_nested_if() -> bool {
     let val = match () {

src/test/mir-opt/const_goto_storage.match_nested_if.ConstGoto.diff

@@ -1,3 +1,5 @@
+// unit-test: Deaggregator
+
 struct Baz {
     x: usize,
     y: f32,

src/test/mir-opt/const_goto_storage.rs

@@ -1,3 +1,5 @@
+// unit-test: Deaggregator
+
 enum Baz {
     Empty,
     Foo { x: usize },

src/test/mir-opt/deaggregator_test.rs

@@ -1,3 +1,4 @@
+// unit-test: Deaggregator
 // Test that deaggregate fires in more than one basic block
 
 enum Foo {