Clean up unnecessary headers/flags in coverage mir-opt tests

These headers and flags were historically needed, but are now unnecessary due
to various changes in how coverage information is stored in MIR.

tests/mir-opt/instrument_coverage.bar.InstrumentCoverage.diff

@@ -4,7 +4,7 @@
   fn bar() -> bool {
       let mut _0: bool;
 
-+     coverage Code(Counter(0)) => /the/src/instrument_coverage.rs:21:1 - 23:2;
++     coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:19:1 - 21:2;
 + 
       bb0: {
 +         Coverage::CounterIncrement(0);

tests/mir-opt/instrument_coverage.main.InstrumentCoverage.diff

@@ -9,11 +9,11 @@
 
 +     coverage ExpressionId(0) => Expression { lhs: Counter(0), op: Add, rhs: Counter(1) };
 +     coverage ExpressionId(1) => Expression { lhs: Expression(0), op: Subtract, rhs: Counter(1) };
-+     coverage Code(Counter(0)) => /the/src/instrument_coverage.rs:12:1 - 12:11;
-+     coverage Code(Expression(0)) => /the/src/instrument_coverage.rs:13:5 - 14:17;
-+     coverage Code(Expression(1)) => /the/src/instrument_coverage.rs:15:13 - 15:18;
-+     coverage Code(Counter(1)) => /the/src/instrument_coverage.rs:16:10 - 16:11;
-+     coverage Code(Expression(1)) => /the/src/instrument_coverage.rs:18:1 - 18:2;
++     coverage Code(Counter(0)) => $DIR/instrument_coverage.rs:10:1 - 10:11;
++     coverage Code(Expression(0)) => $DIR/instrument_coverage.rs:11:5 - 12:17;
++     coverage Code(Expression(1)) => $DIR/instrument_coverage.rs:13:13 - 13:18;
++     coverage Code(Counter(1)) => $DIR/instrument_coverage.rs:14:10 - 14:11;
++     coverage Code(Expression(1)) => $DIR/instrument_coverage.rs:16:1 - 16:2;
 + 
       bb0: {
 +         Coverage::CounterIncrement(0);

tests/mir-opt/instrument_coverage.rs

@@ -1,11 +1,9 @@
-// skip-filecheck
-// Test that `-C instrument-coverage` injects Coverage statements. The Coverage Counter statements
-// are later converted into LLVM instrprof.increment intrinsics, during codegen.
+// Test that `-C instrument-coverage` injects Coverage statements.
+// The Coverage::CounterIncrement statements are later converted into LLVM
+// instrprof.increment intrinsics, during codegen.
 
 //@ unit-test: InstrumentCoverage
-//@ needs-profiler-support
-//@ ignore-windows
-//@ compile-flags: -C instrument-coverage --remap-path-prefix={{src-base}}=/the/src
+//@ compile-flags: -Cinstrument-coverage -Zno-profiler-runtime
 
 // EMIT_MIR instrument_coverage.main.InstrumentCoverage.diff
 // EMIT_MIR instrument_coverage.bar.InstrumentCoverage.diff
@@ -22,17 +20,9 @@ fn bar() -> bool {
     true
 }
 
-// Note that the MIR with injected coverage intrinsics includes references to source locations,
-// including the source file absolute path. Typically, MIR pretty print output with file
-// references are safe because the file prefixes are substituted with `$DIR`, but in this case
-// the file references are encoded as function arguments, with an `Operand` type representation
-// (`Slice` `Allocation` interned byte array) that cannot be normalized by simple substitution.
-//
-// The first workaround is to use the `SourceMap`-supported `--remap-path-prefix` option; however,
-// the implementation of the `--remap-path-prefix` option currently joins the new prefix and the
-// remaining source path with an OS-specific path separator (`\` on Windows). This difference still
-// shows up in the byte array representation of the path, causing Windows tests to fail to match
-// blessed results baselined with a `/` path separator.
-//
-// Since this `mir-opt` test does not have any significant platform dependencies, other than the
-// path separator differences, the final workaround is to disable testing on Windows.
+// CHECK:     coverage ExpressionId({{[0-9]+}}) =>
+// CHECK-DAG: coverage Code(Counter({{[0-9]+}})) =>
+// CHECK-DAG: coverage Code(Expression({{[0-9]+}})) =>
+// CHECK:     bb0:
+// CHECK-DAG: Coverage::ExpressionUsed({{[0-9]+}})
+// CHECK-DAG: Coverage::CounterIncrement({{[0-9]+}})

tests/mir-opt/instrument_coverage_cleanup.main.CleanupPostBorrowck.diff

@@ -5,15 +5,15 @@
       let mut _0: ();
       let mut _1: bool;
 
-      coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => /the/src/instrument_coverage_cleanup.rs:15:8: 15:36 (#0)
+      coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0)
 
       coverage ExpressionId(0) => Expression { lhs: Counter(0), op: Subtract, rhs: Counter(1) };
       coverage ExpressionId(1) => Expression { lhs: Counter(1), op: Add, rhs: Expression(0) };
-      coverage Code(Counter(0)) => /the/src/instrument_coverage_cleanup.rs:14:1 - 15:36;
-      coverage Code(Expression(0)) => /the/src/instrument_coverage_cleanup.rs:15:37 - 15:39;
-      coverage Code(Counter(1)) => /the/src/instrument_coverage_cleanup.rs:15:39 - 15:40;
-      coverage Code(Expression(1)) => /the/src/instrument_coverage_cleanup.rs:16:1 - 16:2;
-      coverage Branch { true_term: Expression(0), false_term: Counter(1) } => /the/src/instrument_coverage_cleanup.rs:15:8 - 15:36;
+      coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:13:1 - 14:36;
+      coverage Code(Expression(0)) => $DIR/instrument_coverage_cleanup.rs:14:37 - 14:39;
+      coverage Code(Counter(1)) => $DIR/instrument_coverage_cleanup.rs:14:39 - 14:40;
+      coverage Code(Expression(1)) => $DIR/instrument_coverage_cleanup.rs:15:1 - 15:2;
+      coverage Branch { true_term: Expression(0), false_term: Counter(1) } => $DIR/instrument_coverage_cleanup.rs:14:8 - 14:36;
 
       bb0: {
           Coverage::CounterIncrement(0);

tests/mir-opt/instrument_coverage_cleanup.main.InstrumentCoverage.diff

@@ -5,15 +5,15 @@
       let mut _0: ();
       let mut _1: bool;
 
-      coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => /the/src/instrument_coverage_cleanup.rs:15:8: 15:36 (#0)
+      coverage branch { true: BlockMarkerId(0), false: BlockMarkerId(1) } => $DIR/instrument_coverage_cleanup.rs:14:8: 14:36 (#0)
 
 +     coverage ExpressionId(0) => Expression { lhs: Counter(0), op: Subtract, rhs: Counter(1) };
 +     coverage ExpressionId(1) => Expression { lhs: Counter(1), op: Add, rhs: Expression(0) };
-+     coverage Code(Counter(0)) => /the/src/instrument_coverage_cleanup.rs:14:1 - 15:36;
-+     coverage Code(Expression(0)) => /the/src/instrument_coverage_cleanup.rs:15:37 - 15:39;
-+     coverage Code(Counter(1)) => /the/src/instrument_coverage_cleanup.rs:15:39 - 15:40;
-+     coverage Code(Expression(1)) => /the/src/instrument_coverage_cleanup.rs:16:1 - 16:2;
-+     coverage Branch { true_term: Expression(0), false_term: Counter(1) } => /the/src/instrument_coverage_cleanup.rs:15:8 - 15:36;
++     coverage Code(Counter(0)) => $DIR/instrument_coverage_cleanup.rs:13:1 - 14:36;
++     coverage Code(Expression(0)) => $DIR/instrument_coverage_cleanup.rs:14:37 - 14:39;
++     coverage Code(Counter(1)) => $DIR/instrument_coverage_cleanup.rs:14:39 - 14:40;
++     coverage Code(Expression(1)) => $DIR/instrument_coverage_cleanup.rs:15:1 - 15:2;
++     coverage Branch { true_term: Expression(0), false_term: Counter(1) } => $DIR/instrument_coverage_cleanup.rs:14:8 - 14:36;
 + 
       bb0: {
 +         Coverage::CounterIncrement(0);

tests/mir-opt/instrument_coverage_cleanup.rs

@@ -7,7 +7,6 @@
 
 //@ unit-test: InstrumentCoverage
 //@ compile-flags: -Cinstrument-coverage -Zcoverage-options=branch -Zno-profiler-runtime
-//@ compile-flags: --remap-path-prefix={{src-base}}=/the/src
 
 // EMIT_MIR instrument_coverage_cleanup.main.InstrumentCoverage.diff
 // EMIT_MIR instrument_coverage_cleanup.main.CleanupPostBorrowck.diff