coverage: Treat each match arm as a "branch" for branch coverage

rust-lang · Apr 19, 2024 · 00b4b52 · 00b4b52
1 parent 9068838
commit 00b4b52
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Showing 8 changed files with 199 additions and 50 deletions.
diff --git a/compiler/rustc_mir_build/src/build/coverageinfo.rs b/compiler/rustc_mir_build/src/build/coverageinfo.rs
@@ -7,6 +7,7 @@ use rustc_middle::mir::{self, BasicBlock, SourceInfo, SourceScope, UnOp};
 use rustc_middle::thir::{ExprId, ExprKind, Thir};
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::LocalDefId;
+use rustc_span::Span;
 
 use crate::build::{Builder, CFG};
 
@@ -112,6 +113,31 @@ impl BranchInfoBuilder {
         ]);
     }
 
+    fn visit_coverage_match_expr(
+        &mut self,
+        cfg: &mut CFG<'_>,
+        scope: SourceScope,
+        arms: impl Iterator<Item = (Span, Option<BasicBlock>)>,
+    ) {
+        let Some(arms) = arms
+            .map(|(span, pre_binding_block)| Some((span, pre_binding_block?)))
+            .collect::<Option<Vec<_>>>()
+        else {
+            return;
+        };
+
+        let match_arms = arms
+            .into_iter()
+            .map(|(span, block)| {
+                let source_info = SourceInfo { span, scope };
+                let marker = self.inject_block_marker(cfg, source_info, block);
+                BranchArm { span, marker }
+            })
+            .collect::<Vec<_>>();
+
+        self.branch_arm_lists.push(match_arms);
+    }
+
     fn next_block_marker_id(&mut self) -> BlockMarkerId {
         let id = BlockMarkerId::from_usize(self.num_block_markers);
         self.num_block_markers += 1;
@@ -168,4 +194,15 @@ impl Builder<'_, '_> {
             else_block,
         );
     }
+
+    /// If branch coverage is enabled, inject marker statements into the given
+    /// match-arm blocks, and record their IDs in the table of branch arm lists.
+    pub(crate) fn visit_coverage_match_expr(
+        &mut self,
+        arms: impl Iterator<Item = (Span, Option<BasicBlock>)>,
+    ) {
+        let Some(branch_info) = self.coverage_branch_info.as_mut() else { return };
+
+        branch_info.visit_coverage_match_expr(&mut self.cfg, self.source_scope, arms);
+    }
 }
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -315,6 +315,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             &mut candidates,
         );
 
+        self.visit_coverage_match_expr(
+            candidates.iter().map(|c| (c.extra_data.span, c.pre_binding_block)),
+        );
+
         self.lower_match_arms(
             destination,
             scrutinee_place,

diff --git a/tests/coverage/branch/guard.cov-map b/tests/coverage/branch/guard.cov-map
@@ -1,32 +1,47 @@
 Function name: guard::branch_match_guard
-Raw bytes (85): 0x[01, 01, 06, 19, 0d, 05, 09, 0f, 15, 13, 11, 17, 0d, 05, 09, 0d, 01, 0c, 01, 01, 10, 1d, 03, 0b, 00, 0c, 15, 01, 14, 02, 0a, 0d, 03, 0e, 00, 0f, 19, 00, 14, 00, 19, 20, 0d, 02, 00, 14, 00, 1e, 0d, 00, 1d, 02, 0a, 11, 03, 0e, 00, 0f, 1d, 00, 14, 00, 19, 20, 11, 09, 00, 14, 00, 1e, 11, 00, 1d, 02, 0a, 17, 03, 0e, 02, 0a, 0b, 04, 01, 00, 02]
+Raw bytes (118): 0x[01, 01, 0c, 19, 0f, 1d, 2f, 05, 09, 1d, 2f, 05, 09, 19, 0d, 05, 09, 05, 09, 27, 15, 2b, 11, 2f, 0d, 05, 09, 10, 01, 0c, 01, 01, 10, 1d, 03, 0b, 00, 0c, 20, 15, 03, 01, 09, 00, 10, 15, 00, 14, 02, 0a, 20, 19, 0f, 03, 09, 00, 10, 0d, 00, 0e, 00, 0f, 19, 00, 14, 00, 19, 20, 0d, 16, 00, 14, 00, 1e, 0d, 00, 1d, 02, 0a, 20, 1d, 2f, 03, 09, 00, 10, 11, 00, 0e, 00, 0f, 1d, 00, 14, 00, 19, 20, 11, 09, 00, 14, 00, 1e, 11, 00, 1d, 02, 0a, 2f, 03, 0e, 02, 0a, 23, 04, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 6
-- expression 0 operands: lhs = Counter(6), rhs = Counter(3)
-- expression 1 operands: lhs = Counter(1), rhs = Counter(2)
-- expression 2 operands: lhs = Expression(3, Add), rhs = Counter(5)
-- expression 3 operands: lhs = Expression(4, Add), rhs = Counter(4)
-- expression 4 operands: lhs = Expression(5, Add), rhs = Counter(3)
-- expression 5 operands: lhs = Counter(1), rhs = Counter(2)
-Number of file 0 mappings: 13
+Number of expressions: 12
+- expression 0 operands: lhs = Counter(6), rhs = Expression(3, Add)
+- expression 1 operands: lhs = Counter(7), rhs = Expression(11, Add)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 3 operands: lhs = Counter(7), rhs = Expression(11, Add)
+- expression 4 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 5 operands: lhs = Counter(6), rhs = Counter(3)
+- expression 6 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 7 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 8 operands: lhs = Expression(9, Add), rhs = Counter(5)
+- expression 9 operands: lhs = Expression(10, Add), rhs = Counter(4)
+- expression 10 operands: lhs = Expression(11, Add), rhs = Counter(3)
+- expression 11 operands: lhs = Counter(1), rhs = Counter(2)
+Number of file 0 mappings: 16
 - Code(Counter(0)) at (prev + 12, 1) to (start + 1, 16)
 - Code(Counter(7)) at (prev + 3, 11) to (start + 0, 12)
-- Code(Counter(5)) at (prev + 1, 20) to (start + 2, 10)
-- Code(Counter(3)) at (prev + 3, 14) to (start + 0, 15)
+- Branch { true: Counter(5), false: Expression(0, Add) } at (prev + 1, 9) to (start + 0, 16)
+    true  = c5
+    false = (c6 + (c7 + (c1 + c2)))
+- Code(Counter(5)) at (prev + 0, 20) to (start + 2, 10)
+- Branch { true: Counter(6), false: Expression(3, Add) } at (prev + 3, 9) to (start + 0, 16)
+    true  = c6
+    false = (c7 + (c1 + c2))
+- Code(Counter(3)) at (prev + 0, 14) to (start + 0, 15)
 - Code(Counter(6)) at (prev + 0, 20) to (start + 0, 25)
-- Branch { true: Counter(3), false: Expression(0, Sub) } at (prev + 0, 20) to (start + 0, 30)
+- Branch { true: Counter(3), false: Expression(5, Sub) } at (prev + 0, 20) to (start + 0, 30)
     true  = c3
     false = (c6 - c3)
 - Code(Counter(3)) at (prev + 0, 29) to (start + 2, 10)
-- Code(Counter(4)) at (prev + 3, 14) to (start + 0, 15)
+- Branch { true: Counter(7), false: Expression(11, Add) } at (prev + 3, 9) to (start + 0, 16)
+    true  = c7
+    false = (c1 + c2)
+- Code(Counter(4)) at (prev + 0, 14) to (start + 0, 15)
 - Code(Counter(7)) at (prev + 0, 20) to (start + 0, 25)
 - Branch { true: Counter(4), false: Counter(2) } at (prev + 0, 20) to (start + 0, 30)
     true  = c4
     false = c2
 - Code(Counter(4)) at (prev + 0, 29) to (start + 2, 10)
-- Code(Expression(5, Add)) at (prev + 3, 14) to (start + 2, 10)
+- Code(Expression(11, Add)) at (prev + 3, 14) to (start + 2, 10)
     = (c1 + c2)
-- Code(Expression(2, Add)) at (prev + 4, 1) to (start + 0, 2)
+- Code(Expression(8, Add)) at (prev + 4, 1) to (start + 0, 2)
     = ((((c1 + c2) + c3) + c4) + c5)
 
diff --git a/tests/coverage/branch/guard.coverage b/tests/coverage/branch/guard.coverage
@@ -14,17 +14,22 @@
    LL|       |
    LL|      1|    match x {
    LL|      1|        Some(0) => {
+  ------------------
+  |  Branch (LL:9): [True: 1, False: 4]
+  ------------------
    LL|      1|            println!("zero");
    LL|      1|        }
    LL|      3|        Some(x) if x % 2 == 0 => {
                            ^2
   ------------------
+  |  Branch (LL:9): [True: 3, False: 1]
   |  Branch (LL:20): [True: 2, False: 1]
   ------------------
    LL|      2|            println!("is nonzero and even");
    LL|      2|        }
    LL|      1|        Some(x) if x % 3 == 0 => {
   ------------------
+  |  Branch (LL:9): [True: 1, False: 0]
   |  Branch (LL:20): [True: 1, False: 0]
   ------------------
    LL|      1|            println!("is nonzero and odd, but divisible by 3");

diff --git a/tests/coverage/branch/match-arms.cov-map b/tests/coverage/branch/match-arms.cov-map
@@ -1,60 +1,122 @@
 Function name: match_arms::guards
-Raw bytes (88): 0x[01, 01, 08, 07, 15, 0b, 11, 0f, 0d, 00, 09, 17, 25, 1b, 21, 1f, 1d, 03, 19, 0c, 01, 30, 01, 01, 10, 29, 03, 0b, 00, 10, 19, 01, 11, 00, 29, 20, 19, 09, 00, 17, 00, 1b, 1d, 01, 11, 00, 29, 20, 1d, 0d, 00, 17, 00, 1b, 21, 01, 11, 00, 29, 20, 21, 11, 00, 17, 00, 1b, 25, 01, 11, 00, 29, 20, 25, 15, 00, 17, 00, 1b, 03, 01, 0e, 00, 18, 13, 03, 05, 01, 02]
+Raw bytes (180): 0x[01, 01, 22, 31, 1f, 2d, 37, 29, 7b, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 2d, 37, 29, 7b, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 29, 7b, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 6f, 25, 73, 21, 77, 1d, 7b, 19, 7f, 15, 83, 01, 11, 87, 01, 0d, 00, 09, 10, 01, 30, 01, 01, 10, 29, 03, 0b, 00, 10, 20, 35, 03, 01, 09, 00, 13, 19, 00, 11, 00, 29, 20, 19, 09, 00, 17, 00, 1b, 20, 31, 1f, 01, 09, 00, 13, 1d, 00, 11, 00, 29, 20, 1d, 0d, 00, 17, 00, 1b, 20, 2d, 37, 01, 09, 00, 13, 21, 00, 11, 00, 29, 20, 21, 11, 00, 17, 00, 1b, 20, 29, 7b, 01, 09, 00, 13, 25, 00, 11, 00, 29, 20, 25, 15, 00, 17, 00, 1b, 7b, 01, 0e, 00, 18, 6b, 03, 05, 01, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 8
-- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(5)
-- expression 1 operands: lhs = Expression(2, Add), rhs = Counter(4)
-- expression 2 operands: lhs = Expression(3, Add), rhs = Counter(3)
-- expression 3 operands: lhs = Zero, rhs = Counter(2)
-- expression 4 operands: lhs = Expression(5, Add), rhs = Counter(9)
-- expression 5 operands: lhs = Expression(6, Add), rhs = Counter(8)
-- expression 6 operands: lhs = Expression(7, Add), rhs = Counter(7)
-- expression 7 operands: lhs = Expression(0, Add), rhs = Counter(6)
-Number of file 0 mappings: 12
+Number of expressions: 34
+- expression 0 operands: lhs = Counter(12), rhs = Expression(7, Add)
+- expression 1 operands: lhs = Counter(11), rhs = Expression(13, Add)
+- expression 2 operands: lhs = Counter(10), rhs = Expression(30, Add)
+- expression 3 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 4 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 5 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 6 operands: lhs = Zero, rhs = Counter(2)
+- expression 7 operands: lhs = Counter(11), rhs = Expression(13, Add)
+- expression 8 operands: lhs = Counter(10), rhs = Expression(30, Add)
+- expression 9 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 10 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 11 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 12 operands: lhs = Zero, rhs = Counter(2)
+- expression 13 operands: lhs = Counter(10), rhs = Expression(30, Add)
+- expression 14 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 15 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 16 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 17 operands: lhs = Zero, rhs = Counter(2)
+- expression 18 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 19 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 20 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 21 operands: lhs = Zero, rhs = Counter(2)
+- expression 22 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 23 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 24 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 25 operands: lhs = Zero, rhs = Counter(2)
+- expression 26 operands: lhs = Expression(27, Add), rhs = Counter(9)
+- expression 27 operands: lhs = Expression(28, Add), rhs = Counter(8)
+- expression 28 operands: lhs = Expression(29, Add), rhs = Counter(7)
+- expression 29 operands: lhs = Expression(30, Add), rhs = Counter(6)
+- expression 30 operands: lhs = Expression(31, Add), rhs = Counter(5)
+- expression 31 operands: lhs = Expression(32, Add), rhs = Counter(4)
+- expression 32 operands: lhs = Expression(33, Add), rhs = Counter(3)
+- expression 33 operands: lhs = Zero, rhs = Counter(2)
+Number of file 0 mappings: 16
 - Code(Counter(0)) at (prev + 48, 1) to (start + 1, 16)
 - Code(Counter(10)) at (prev + 3, 11) to (start + 0, 16)
-- Code(Counter(6)) at (prev + 1, 17) to (start + 0, 41)
+- Branch { true: Counter(13), false: Expression(0, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c13
+    false = (c12 + (c11 + (c10 + ((((Zero + c2) + c3) + c4) + c5))))
+- Code(Counter(6)) at (prev + 0, 17) to (start + 0, 41)
 - Branch { true: Counter(6), false: Counter(2) } at (prev + 0, 23) to (start + 0, 27)
     true  = c6
     false = c2
-- Code(Counter(7)) at (prev + 1, 17) to (start + 0, 41)
+- Branch { true: Counter(12), false: Expression(7, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c12
+    false = (c11 + (c10 + ((((Zero + c2) + c3) + c4) + c5)))
+- Code(Counter(7)) at (prev + 0, 17) to (start + 0, 41)
 - Branch { true: Counter(7), false: Counter(3) } at (prev + 0, 23) to (start + 0, 27)
     true  = c7
     false = c3
-- Code(Counter(8)) at (prev + 1, 17) to (start + 0, 41)
+- Branch { true: Counter(11), false: Expression(13, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c11
+    false = (c10 + ((((Zero + c2) + c3) + c4) + c5))
+- Code(Counter(8)) at (prev + 0, 17) to (start + 0, 41)
 - Branch { true: Counter(8), false: Counter(4) } at (prev + 0, 23) to (start + 0, 27)
     true  = c8
     false = c4
-- Code(Counter(9)) at (prev + 1, 17) to (start + 0, 41)
+- Branch { true: Counter(10), false: Expression(30, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c10
+    false = ((((Zero + c2) + c3) + c4) + c5)
+- Code(Counter(9)) at (prev + 0, 17) to (start + 0, 41)
 - Branch { true: Counter(9), false: Counter(5) } at (prev + 0, 23) to (start + 0, 27)
     true  = c9
     false = c5
-- Code(Expression(0, Add)) at (prev + 1, 14) to (start + 0, 24)
+- Code(Expression(30, Add)) at (prev + 1, 14) to (start + 0, 24)
     = ((((Zero + c2) + c3) + c4) + c5)
-- Code(Expression(4, Add)) at (prev + 3, 5) to (start + 1, 2)
+- Code(Expression(26, Add)) at (prev + 3, 5) to (start + 1, 2)
     = ((((((((Zero + c2) + c3) + c4) + c5) + c6) + c7) + c8) + c9)
 
 Function name: match_arms::match_arms
-Raw bytes (51): 0x[01, 01, 06, 05, 07, 0b, 11, 09, 0d, 13, 02, 17, 09, 11, 0d, 07, 01, 18, 01, 01, 10, 05, 03, 0b, 00, 10, 11, 01, 11, 00, 21, 0d, 01, 11, 00, 21, 09, 01, 11, 00, 21, 02, 01, 11, 00, 21, 0f, 03, 05, 01, 02]
+Raw bytes (102): 0x[01, 01, 15, 0d, 17, 09, 4a, 05, 4f, 53, 11, 09, 0d, 09, 4a, 05, 4f, 53, 11, 09, 0d, 05, 4f, 53, 11, 09, 0d, 05, 4f, 53, 11, 09, 0d, 43, 4a, 47, 09, 11, 0d, 05, 4f, 53, 11, 09, 0d, 0a, 01, 18, 01, 01, 10, 05, 03, 0b, 00, 10, 20, 11, 03, 01, 09, 00, 13, 11, 00, 11, 00, 21, 20, 0d, 17, 01, 09, 00, 13, 0d, 00, 11, 00, 21, 20, 09, 4a, 01, 09, 00, 13, 09, 00, 11, 00, 21, 4a, 01, 11, 00, 21, 3f, 03, 05, 01, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 6
-- expression 0 operands: lhs = Counter(1), rhs = Expression(1, Add)
-- expression 1 operands: lhs = Expression(2, Add), rhs = Counter(4)
-- expression 2 operands: lhs = Counter(2), rhs = Counter(3)
-- expression 3 operands: lhs = Expression(4, Add), rhs = Expression(0, Sub)
-- expression 4 operands: lhs = Expression(5, Add), rhs = Counter(2)
-- expression 5 operands: lhs = Counter(4), rhs = Counter(3)
-Number of file 0 mappings: 7
+Number of expressions: 21
+- expression 0 operands: lhs = Counter(3), rhs = Expression(5, Add)
+- expression 1 operands: lhs = Counter(2), rhs = Expression(18, Sub)
+- expression 2 operands: lhs = Counter(1), rhs = Expression(19, Add)
+- expression 3 operands: lhs = Expression(20, Add), rhs = Counter(4)
+- expression 4 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 5 operands: lhs = Counter(2), rhs = Expression(18, Sub)
+- expression 6 operands: lhs = Counter(1), rhs = Expression(19, Add)
+- expression 7 operands: lhs = Expression(20, Add), rhs = Counter(4)
+- expression 8 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 9 operands: lhs = Counter(1), rhs = Expression(19, Add)
+- expression 10 operands: lhs = Expression(20, Add), rhs = Counter(4)
+- expression 11 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 12 operands: lhs = Counter(1), rhs = Expression(19, Add)
+- expression 13 operands: lhs = Expression(20, Add), rhs = Counter(4)
+- expression 14 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 15 operands: lhs = Expression(16, Add), rhs = Expression(18, Sub)
+- expression 16 operands: lhs = Expression(17, Add), rhs = Counter(2)
+- expression 17 operands: lhs = Counter(4), rhs = Counter(3)
+- expression 18 operands: lhs = Counter(1), rhs = Expression(19, Add)
+- expression 19 operands: lhs = Expression(20, Add), rhs = Counter(4)
+- expression 20 operands: lhs = Counter(2), rhs = Counter(3)
+Number of file 0 mappings: 10
 - Code(Counter(0)) at (prev + 24, 1) to (start + 1, 16)
 - Code(Counter(1)) at (prev + 3, 11) to (start + 0, 16)
-- Code(Counter(4)) at (prev + 1, 17) to (start + 0, 33)
-- Code(Counter(3)) at (prev + 1, 17) to (start + 0, 33)
-- Code(Counter(2)) at (prev + 1, 17) to (start + 0, 33)
-- Code(Expression(0, Sub)) at (prev + 1, 17) to (start + 0, 33)
+- Branch { true: Counter(4), false: Expression(0, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c4
+    false = (c3 + (c2 + (c1 - ((c2 + c3) + c4))))
+- Code(Counter(4)) at (prev + 0, 17) to (start + 0, 33)
+- Branch { true: Counter(3), false: Expression(5, Add) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c3
+    false = (c2 + (c1 - ((c2 + c3) + c4)))
+- Code(Counter(3)) at (prev + 0, 17) to (start + 0, 33)
+- Branch { true: Counter(2), false: Expression(18, Sub) } at (prev + 1, 9) to (start + 0, 19)
+    true  = c2
+    false = (c1 - ((c2 + c3) + c4))
+- Code(Counter(2)) at (prev + 0, 17) to (start + 0, 33)
+- Code(Expression(18, Sub)) at (prev + 1, 17) to (start + 0, 33)
     = (c1 - ((c2 + c3) + c4))
-- Code(Expression(3, Add)) at (prev + 3, 5) to (start + 1, 2)
+- Code(Expression(15, Add)) at (prev + 3, 5) to (start + 1, 2)
     = (((c4 + c3) + c2) + (c1 - ((c2 + c3) + c4)))
 
 Function name: match_arms::or_patterns

diff --git a/tests/coverage/branch/match-arms.coverage b/tests/coverage/branch/match-arms.coverage
@@ -26,8 +26,17 @@
    LL|       |
    LL|     15|    match value {
    LL|      8|        Enum::D(d) => consume(d),
+  ------------------
+  |  Branch (LL:9): [True: 8, False: 7]
+  ------------------
    LL|      4|        Enum::C(c) => consume(c),
+  ------------------
+  |  Branch (LL:9): [True: 4, False: 3]
+  ------------------
    LL|      2|        Enum::B(b) => consume(b),
+  ------------------
+  |  Branch (LL:9): [True: 2, False: 1]
+  ------------------
    LL|      1|        Enum::A(a) => consume(a),
    LL|       |    }
    LL|       |
@@ -53,18 +62,22 @@
    LL|      3|    match value {
    LL|      8|        Enum::D(d) if cond => consume(d),
   ------------------
+  |  Branch (LL:9): [True: 24, False: 51]
   |  Branch (LL:23): [True: 8, False: 16]
   ------------------
    LL|      4|        Enum::C(c) if cond => consume(c),
   ------------------
+  |  Branch (LL:9): [True: 12, False: 39]
   |  Branch (LL:23): [True: 4, False: 8]
   ------------------
    LL|      2|        Enum::B(b) if cond => consume(b),
   ------------------
+  |  Branch (LL:9): [True: 6, False: 33]
   |  Branch (LL:23): [True: 2, False: 4]
   ------------------
    LL|      1|        Enum::A(a) if cond => consume(a),
   ------------------
+  |  Branch (LL:9): [True: 3, False: 30]
   |  Branch (LL:23): [True: 1, False: 2]
   ------------------
    LL|     30|        _ => consume(0),
@@ -100,6 +113,4 @@
    LL|       |        call_everything(Enum::D(d));
    LL|       |    }
    LL|       |}
-   LL|       |
-   LL|       |// FIXME(#124118) Actually instrument match arms for branch coverage.
 
diff --git a/tests/coverage/branch/match-arms.rs b/tests/coverage/branch/match-arms.rs
@@ -86,5 +86,3 @@ fn main() {
         call_everything(Enum::D(d));
     }
 }
-
-// FIXME(#124118) Actually instrument match arms for branch coverage.