Rollup merge of #125766 - RenjiSann:fresh-mcdc-branch-on-bool, r=nnethercote

MCDC Coverage: instrument last boolean RHS operands from condition coverage

Fresh PR from #124652

--

This PR ensures that the top-level boolean expressions that are not part of the control flow are correctly instrumented thanks to condition coverage.

See discussion on https://github.com/rust-lang/rust/issues/124120.
Depends on `@Zalathar` 's condition coverage implementation #125756.

5 files changed, 526 insertions, 23 deletions

diff --git a/compiler/rustc_mir_build/src/build/coverageinfo.rs b/compiler/rustc_mir_build/src/build/coverageinfo.rs
index 855dcbbcb34..876faca5172 100644
--- a/compiler/rustc_mir_build/src/build/coverageinfo.rs
+++ b/compiler/rustc_mir_build/src/build/coverageinfo.rs
@@ -118,17 +118,35 @@ impl BranchInfoBuilder {
         }
     }
 
-    fn add_two_way_branch<'tcx>(
+    fn register_two_way_branch<'tcx>(
         &mut self,
+        tcx: TyCtxt<'tcx>,
         cfg: &mut CFG<'tcx>,
         source_info: SourceInfo,
         true_block: BasicBlock,
         false_block: BasicBlock,
     ) {
-        let true_marker = self.markers.inject_block_marker(cfg, source_info, true_block);
-        let false_marker = self.markers.inject_block_marker(cfg, source_info, false_block);
-
-        self.branch_spans.push(BranchSpan { span: source_info.span, true_marker, false_marker });
+        // Separate path for handling branches when MC/DC is enabled.
+        if let Some(mcdc_info) = self.mcdc_info.as_mut() {
+            let inject_block_marker =
+                |source_info, block| self.markers.inject_block_marker(cfg, source_info, block);
+            mcdc_info.visit_evaluated_condition(
+                tcx,
+                source_info,
+                true_block,
+                false_block,
+                inject_block_marker,
+            );
+        } else {
+            let true_marker = self.markers.inject_block_marker(cfg, source_info, true_block);
+            let false_marker = self.markers.inject_block_marker(cfg, source_info, false_block);
+
+            self.branch_spans.push(BranchSpan {
+                span: source_info.span,
+                true_marker,
+                false_marker,
+            });
+        }
     }
 
     pub(crate) fn into_done(self) -> Option<Box<mir::coverage::BranchInfo>> {
@@ -205,7 +223,14 @@ impl<'tcx> Builder<'_, 'tcx> {
             mir::TerminatorKind::if_(mir::Operand::Copy(place), true_block, false_block),
         );
 
-        branch_info.add_two_way_branch(&mut self.cfg, source_info, true_block, false_block);
+        // Separate path for handling branches when MC/DC is enabled.
+        branch_info.register_two_way_branch(
+            self.tcx,
+            &mut self.cfg,
+            source_info,
+            true_block,
+            false_block,
+        );
 
         let join_block = self.cfg.start_new_block();
         self.cfg.goto(true_block, source_info, join_block);
@@ -236,22 +261,13 @@ impl<'tcx> Builder<'_, 'tcx> {
 
         let source_info = SourceInfo { span: self.thir[expr_id].span, scope: self.source_scope };
 
-        // Separate path for handling branches when MC/DC is enabled.
-        if let Some(mcdc_info) = branch_info.mcdc_info.as_mut() {
-            let inject_block_marker = |source_info, block| {
-                branch_info.markers.inject_block_marker(&mut self.cfg, source_info, block)
-            };
-            mcdc_info.visit_evaluated_condition(
-                self.tcx,
-                source_info,
-                then_block,
-                else_block,
-                inject_block_marker,
-            );
-            return;
-        }
-
-        branch_info.add_two_way_branch(&mut self.cfg, source_info, then_block, else_block);
+        branch_info.register_two_way_branch(
+            self.tcx,
+            &mut self.cfg,
+            source_info,
+            then_block,
+            else_block,
+        );
     }
 
     /// If branch coverage is enabled, inject marker statements into `true_block`
@@ -270,6 +286,12 @@ impl<'tcx> Builder<'_, 'tcx> {
         // FIXME(#124144) This may need special handling when MC/DC is enabled.
 
         let source_info = SourceInfo { span: pattern.span, scope: self.source_scope };
-        branch_info.add_two_way_branch(&mut self.cfg, source_info, true_block, false_block);
+        branch_info.register_two_way_branch(
+            self.tcx,
+            &mut self.cfg,
+            source_info,
+            true_block,
+            false_block,
+        );
     }
 }
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index c08a3b6691a..6b4dd8b64a4 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -150,6 +150,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             ExprKind::LogicalOp { op, lhs, rhs } => {
                 let condition_scope = this.local_scope();
                 let source_info = this.source_info(expr.span);
+
+                this.visit_coverage_branch_operation(op, expr.span);
+
                 // We first evaluate the left-hand side of the predicate ...
                 let (then_block, else_block) =
                     this.in_if_then_scope(condition_scope, expr.span, |this| {
diff --git a/tests/coverage/mcdc_non_control_flow.cov-map b/tests/coverage/mcdc_non_control_flow.cov-map
new file mode 100644
index 00000000000..937c36e1f16
--- /dev/null
+++ b/tests/coverage/mcdc_non_control_flow.cov-map
@@ -0,0 +1,204 @@
+Function name: mcdc_non_control_flow::assign_3
+Raw bytes (89): 0x[01, 01, 09, 05, 07, 0b, 11, 09, 0d, 01, 05, 01, 05, 22, 11, 01, 05, 22, 11, 01, 05, 0a, 01, 16, 01, 00, 28, 03, 01, 09, 00, 0a, 01, 00, 0d, 00, 0e, 28, 00, 03, 00, 0d, 00, 18, 30, 05, 22, 01, 00, 02, 00, 0d, 00, 0e, 22, 00, 12, 00, 13, 30, 1e, 11, 02, 03, 00, 00, 12, 00, 13, 1e, 00, 17, 00, 18, 30, 09, 0d, 03, 00, 00, 00, 17, 00, 18, 03, 01, 05, 01, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 9
+- 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 = Counter(0), rhs = Counter(1)
+- expression 4 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 5 operands: lhs = Expression(8, Sub), rhs = Counter(4)
+- expression 6 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 7 operands: lhs = Expression(8, Sub), rhs = Counter(4)
+- expression 8 operands: lhs = Counter(0), rhs = Counter(1)
+Number of file 0 mappings: 10
+- Code(Counter(0)) at (prev + 22, 1) to (start + 0, 40)
+- Code(Expression(0, Add)) at (prev + 1, 9) to (start + 0, 10)
+    = (c1 + ((c2 + c3) + c4))
+- Code(Counter(0)) at (prev + 0, 13) to (start + 0, 14)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 3 } at (prev + 0, 13) to (start + 0, 24)
+- MCDCBranch { true: Counter(1), false: Expression(8, Sub), condition_id: 1, true_next_id: 0, false_next_id: 2 } at (prev + 0, 13) to (start + 0, 14)
+    true  = c1
+    false = (c0 - c1)
+- Code(Expression(8, Sub)) at (prev + 0, 18) to (start + 0, 19)
+    = (c0 - c1)
+- MCDCBranch { true: Expression(7, Sub), false: Counter(4), condition_id: 2, true_next_id: 3, false_next_id: 0 } at (prev + 0, 18) to (start + 0, 19)
+    true  = ((c0 - c1) - c4)
+    false = c4
+- Code(Expression(7, Sub)) at (prev + 0, 23) to (start + 0, 24)
+    = ((c0 - c1) - c4)
+- MCDCBranch { true: Counter(2), false: Counter(3), condition_id: 3, true_next_id: 0, false_next_id: 0 } at (prev + 0, 23) to (start + 0, 24)
+    true  = c2
+    false = c3
+- Code(Expression(0, Add)) at (prev + 1, 5) to (start + 1, 2)
+    = (c1 + ((c2 + c3) + c4))
+
+Function name: mcdc_non_control_flow::assign_3_bis
+Raw bytes (85): 0x[01, 01, 07, 07, 11, 09, 0d, 01, 05, 05, 09, 16, 1a, 05, 09, 01, 05, 0a, 01, 1b, 01, 00, 2c, 03, 01, 09, 00, 0a, 01, 00, 0d, 00, 0e, 28, 00, 03, 00, 0d, 00, 18, 30, 05, 1a, 01, 03, 02, 00, 0d, 00, 0e, 05, 00, 12, 00, 13, 30, 09, 16, 03, 00, 02, 00, 12, 00, 13, 13, 00, 17, 00, 18, 30, 0d, 11, 02, 00, 00, 00, 17, 00, 18, 03, 01, 05, 01, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 7
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(4)
+- expression 1 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 2 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 3 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 4 operands: lhs = Expression(5, Sub), rhs = Expression(6, Sub)
+- expression 5 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 6 operands: lhs = Counter(0), rhs = Counter(1)
+Number of file 0 mappings: 10
+- Code(Counter(0)) at (prev + 27, 1) to (start + 0, 44)
+- Code(Expression(0, Add)) at (prev + 1, 9) to (start + 0, 10)
+    = ((c2 + c3) + c4)
+- Code(Counter(0)) at (prev + 0, 13) to (start + 0, 14)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 3 } at (prev + 0, 13) to (start + 0, 24)
+- MCDCBranch { true: Counter(1), false: Expression(6, Sub), condition_id: 1, true_next_id: 3, false_next_id: 2 } at (prev + 0, 13) to (start + 0, 14)
+    true  = c1
+    false = (c0 - c1)
+- Code(Counter(1)) at (prev + 0, 18) to (start + 0, 19)
+- MCDCBranch { true: Counter(2), false: Expression(5, Sub), condition_id: 3, true_next_id: 0, false_next_id: 2 } at (prev + 0, 18) to (start + 0, 19)
+    true  = c2
+    false = (c1 - c2)
+- Code(Expression(4, Add)) at (prev + 0, 23) to (start + 0, 24)
+    = ((c1 - c2) + (c0 - c1))
+- MCDCBranch { true: Counter(3), false: Counter(4), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 23) to (start + 0, 24)
+    true  = c3
+    false = c4
+- Code(Expression(0, Add)) at (prev + 1, 5) to (start + 1, 2)
+    = ((c2 + c3) + c4)
+
+Function name: mcdc_non_control_flow::assign_and
+Raw bytes (64): 0x[01, 01, 04, 07, 0e, 09, 0d, 01, 05, 01, 05, 08, 01, 0c, 01, 00, 21, 03, 01, 09, 00, 0a, 01, 00, 0d, 00, 0e, 28, 00, 02, 00, 0d, 00, 13, 30, 05, 0e, 01, 02, 00, 00, 0d, 00, 0e, 05, 00, 12, 00, 13, 30, 09, 0d, 02, 00, 00, 00, 12, 00, 13, 03, 01, 05, 01, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 4
+- expression 0 operands: lhs = Expression(1, Add), rhs = Expression(3, Sub)
+- expression 1 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 2 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 3 operands: lhs = Counter(0), rhs = Counter(1)
+Number of file 0 mappings: 8
+- Code(Counter(0)) at (prev + 12, 1) to (start + 0, 33)
+- Code(Expression(0, Add)) at (prev + 1, 9) to (start + 0, 10)
+    = ((c2 + c3) + (c0 - c1))
+- Code(Counter(0)) at (prev + 0, 13) to (start + 0, 14)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 0, 13) to (start + 0, 19)
+- MCDCBranch { true: Counter(1), false: Expression(3, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 14)
+    true  = c1
+    false = (c0 - c1)
+- Code(Counter(1)) at (prev + 0, 18) to (start + 0, 19)
+- MCDCBranch { true: Counter(2), false: Counter(3), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 18) to (start + 0, 19)
+    true  = c2
+    false = c3
+- Code(Expression(0, Add)) at (prev + 1, 5) to (start + 1, 2)
+    = ((c2 + c3) + (c0 - c1))
+
+Function name: mcdc_non_control_flow::assign_or
+Raw bytes (64): 0x[01, 01, 04, 07, 0d, 05, 09, 01, 05, 01, 05, 08, 01, 11, 01, 00, 20, 03, 01, 09, 00, 0a, 01, 00, 0d, 00, 0e, 28, 00, 02, 00, 0d, 00, 13, 30, 05, 0e, 01, 00, 02, 00, 0d, 00, 0e, 0e, 00, 12, 00, 13, 30, 09, 0d, 02, 00, 00, 00, 12, 00, 13, 03, 01, 05, 01, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 4
+- expression 0 operands: lhs = Expression(1, Add), rhs = Counter(3)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(2)
+- expression 2 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 3 operands: lhs = Counter(0), rhs = Counter(1)
+Number of file 0 mappings: 8
+- Code(Counter(0)) at (prev + 17, 1) to (start + 0, 32)
+- Code(Expression(0, Add)) at (prev + 1, 9) to (start + 0, 10)
+    = ((c1 + c2) + c3)
+- Code(Counter(0)) at (prev + 0, 13) to (start + 0, 14)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 0, 13) to (start + 0, 19)
+- MCDCBranch { true: Counter(1), false: Expression(3, Sub), condition_id: 1, true_next_id: 0, false_next_id: 2 } at (prev + 0, 13) to (start + 0, 14)
+    true  = c1
+    false = (c0 - c1)
+- Code(Expression(3, Sub)) at (prev + 0, 18) to (start + 0, 19)
+    = (c0 - c1)
+- MCDCBranch { true: Counter(2), false: Counter(3), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 18) to (start + 0, 19)
+    true  = c2
+    false = c3
+- Code(Expression(0, Add)) at (prev + 1, 5) to (start + 1, 2)
+    = ((c1 + c2) + c3)
+
+Function name: mcdc_non_control_flow::foo
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 25, 01, 02, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 37, 1) to (start + 2, 2)
+
+Function name: mcdc_non_control_flow::func_call
+Raw bytes (52): 0x[01, 01, 03, 01, 05, 0b, 02, 09, 0d, 06, 01, 29, 01, 01, 0a, 28, 00, 02, 01, 09, 00, 0f, 30, 05, 02, 01, 02, 00, 00, 09, 00, 0a, 05, 00, 0e, 00, 0f, 30, 09, 0d, 02, 00, 00, 00, 0e, 00, 0f, 07, 01, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 3
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Expression(2, Add), rhs = Expression(0, Sub)
+- expression 2 operands: lhs = Counter(2), rhs = Counter(3)
+Number of file 0 mappings: 6
+- Code(Counter(0)) at (prev + 41, 1) to (start + 1, 10)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 1, 9) to (start + 0, 15)
+- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 9) to (start + 0, 10)
+    true  = c1
+    false = (c0 - c1)
+- Code(Counter(1)) at (prev + 0, 14) to (start + 0, 15)
+- MCDCBranch { true: Counter(2), false: Counter(3), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 14) to (start + 0, 15)
+    true  = c2
+    false = c3
+- Code(Expression(1, Add)) at (prev + 1, 1) to (start + 0, 2)
+    = ((c2 + c3) + (c0 - c1))
+
+Function name: mcdc_non_control_flow::right_comb_tree
+Raw bytes (139): 0x[01, 01, 13, 07, 1a, 0b, 19, 0f, 15, 13, 11, 09, 0d, 01, 05, 01, 05, 05, 19, 05, 19, 4a, 15, 05, 19, 4a, 15, 05, 19, 46, 11, 4a, 15, 05, 19, 46, 11, 4a, 15, 05, 19, 0e, 01, 20, 01, 00, 41, 03, 01, 09, 00, 0a, 01, 00, 0d, 00, 0e, 28, 00, 05, 00, 0d, 00, 2a, 30, 05, 1a, 01, 02, 00, 00, 0d, 00, 0e, 05, 00, 13, 00, 14, 30, 4a, 19, 02, 03, 00, 00, 13, 00, 14, 4a, 00, 19, 00, 1a, 30, 46, 15, 03, 04, 00, 00, 19, 00, 1a, 46, 00, 1f, 00, 20, 30, 42, 11, 04, 05, 00, 00, 1f, 00, 20, 42, 00, 24, 00, 27, 30, 09, 0d, 05, 00, 00, 00, 24, 00, 27, 03, 01, 05, 01, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 19
+- expression 0 operands: lhs = Expression(1, Add), rhs = Expression(6, Sub)
+- expression 1 operands: lhs = Expression(2, Add), rhs = Counter(6)
+- expression 2 operands: lhs = Expression(3, Add), rhs = Counter(5)
+- expression 3 operands: lhs = Expression(4, Add), rhs = Counter(4)
+- expression 4 operands: lhs = Counter(2), rhs = Counter(3)
+- expression 5 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 6 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 7 operands: lhs = Counter(1), rhs = Counter(6)
+- expression 8 operands: lhs = Counter(1), rhs = Counter(6)
+- expression 9 operands: lhs = Expression(18, Sub), rhs = Counter(5)
+- expression 10 operands: lhs = Counter(1), rhs = Counter(6)
+- expression 11 operands: lhs = Expression(18, Sub), rhs = Counter(5)
+- expression 12 operands: lhs = Counter(1), rhs = Counter(6)
+- expression 13 operands: lhs = Expression(17, Sub), rhs = Counter(4)
+- expression 14 operands: lhs = Expression(18, Sub), rhs = Counter(5)
+- expression 15 operands: lhs = Counter(1), rhs = Counter(6)
+- expression 16 operands: lhs = Expression(17, Sub), rhs = Counter(4)
+- expression 17 operands: lhs = Expression(18, Sub), rhs = Counter(5)
+- expression 18 operands: lhs = Counter(1), rhs = Counter(6)
+Number of file 0 mappings: 14
+- Code(Counter(0)) at (prev + 32, 1) to (start + 0, 65)
+- Code(Expression(0, Add)) at (prev + 1, 9) to (start + 0, 10)
+    = (((((c2 + c3) + c4) + c5) + c6) + (c0 - c1))
+- Code(Counter(0)) at (prev + 0, 13) to (start + 0, 14)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 5 } at (prev + 0, 13) to (start + 0, 42)
+- MCDCBranch { true: Counter(1), false: Expression(6, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 14)
+    true  = c1
+    false = (c0 - c1)
+- Code(Counter(1)) at (prev + 0, 19) to (start + 0, 20)
+- MCDCBranch { true: Expression(18, Sub), false: Counter(6), condition_id: 2, true_next_id: 3, false_next_id: 0 } at (prev + 0, 19) to (start + 0, 20)
+    true  = (c1 - c6)
+    false = c6
+- Code(Expression(18, Sub)) at (prev + 0, 25) to (start + 0, 26)
+    = (c1 - c6)
+- MCDCBranch { true: Expression(17, Sub), false: Counter(5), condition_id: 3, true_next_id: 4, false_next_id: 0 } at (prev + 0, 25) to (start + 0, 26)
+    true  = ((c1 - c6) - c5)
+    false = c5
+- Code(Expression(17, Sub)) at (prev + 0, 31) to (start + 0, 32)
+    = ((c1 - c6) - c5)
+- MCDCBranch { true: Expression(16, Sub), false: Counter(4), condition_id: 4, true_next_id: 5, false_next_id: 0 } at (prev + 0, 31) to (start + 0, 32)
+    true  = (((c1 - c6) - c5) - c4)
+    false = c4
+- Code(Expression(16, Sub)) at (prev + 0, 36) to (start + 0, 39)
+    = (((c1 - c6) - c5) - c4)
+- MCDCBranch { true: Counter(2), false: Counter(3), condition_id: 5, true_next_id: 0, false_next_id: 0 } at (prev + 0, 36) to (start + 0, 39)
+    true  = c2
+    false = c3
+- Code(Expression(0, Add)) at (prev + 1, 5) to (start + 1, 2)
+    = (((((c2 + c3) + c4) + c5) + c6) + (c0 - c1))
+
diff --git a/tests/coverage/mcdc_non_control_flow.coverage b/tests/coverage/mcdc_non_control_flow.coverage
new file mode 100644
index 00000000000..cd733885a98
--- /dev/null
+++ b/tests/coverage/mcdc_non_control_flow.coverage
@@ -0,0 +1,202 @@
+   LL|       |#![feature(coverage_attribute)]
+   LL|       |//@ edition: 2021
+   LL|       |//@ min-llvm-version: 18
+   LL|       |//@ compile-flags: -Zcoverage-options=mcdc
+   LL|       |//@ llvm-cov-flags: --show-mcdc
+   LL|       |
+   LL|       |// This test ensures that boolean expressions that are not inside control flow
+   LL|       |// decisions are correctly instrumented.
+   LL|       |
+   LL|       |use core::hint::black_box;
+   LL|       |
+   LL|      3|fn assign_and(a: bool, b: bool) {
+   LL|      3|    let x = a && b;
+                               ^2
+  ------------------
+  |---> MC/DC Decision Region (LL:13) to (LL:19)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:13)
+  |     Condition C2 --> (LL:18)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  -  = F      }
+  |  2 { T,  F  = F      }
+  |  3 { T,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,3)
+  |  C2-Pair: covered: (2,3)
+  |  MC/DC Coverage for Decision: 100.00%
+  |
+  ------------------
+   LL|      3|    black_box(x);
+   LL|      3|}
+   LL|       |
+   LL|      3|fn assign_or(a: bool, b: bool) {
+   LL|      3|    let x = a || b;
+                               ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:13) to (LL:19)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:13)
+  |     Condition C2 --> (LL:18)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  F  = F      }
+  |  2 { T,  -  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: not covered
+  |  MC/DC Coverage for Decision: 50.00%
+  |
+  ------------------
+   LL|      3|    black_box(x);
+   LL|      3|}
+   LL|       |
+   LL|      4|fn assign_3(a: bool, b: bool, c: bool) {
+   LL|      4|    let x = a || b && c;
+                               ^2   ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:13) to (LL:24)
+  |
+  |  Number of Conditions: 3
+  |     Condition C1 --> (LL:13)
+  |     Condition C2 --> (LL:18)
+  |     Condition C3 --> (LL:23)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2, C3    Result
+  |  1 { F,  F,  -  = F      }
+  |  2 { T,  -,  -  = T      }
+  |  3 { F,  T,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: covered: (1,3)
+  |  C3-Pair: not covered
+  |  MC/DC Coverage for Decision: 66.67%
+  |
+  ------------------
+   LL|      4|    black_box(x);
+   LL|      4|}
+   LL|       |
+   LL|      4|fn assign_3_bis(a: bool, b: bool, c: bool) {
+   LL|      4|    let x = a && b || c;
+                               ^2   ^3
+  ------------------
+  |---> MC/DC Decision Region (LL:13) to (LL:24)
+  |
+  |  Number of Conditions: 3
+  |     Condition C1 --> (LL:13)
+  |     Condition C2 --> (LL:18)
+  |     Condition C3 --> (LL:23)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2, C3    Result
+  |  1 { T,  F,  F  = F      }
+  |  2 { F,  -,  T  = T      }
+  |  3 { T,  T,  -  = T      }
+  |
+  |  C1-Pair: not covered
+  |  C2-Pair: covered: (1,3)
+  |  C3-Pair: not covered
+  |  MC/DC Coverage for Decision: 33.33%
+  |
+  ------------------
+   LL|      4|    black_box(x);
+   LL|      4|}
+   LL|       |
+   LL|      3|fn right_comb_tree(a: bool, b: bool, c: bool, d: bool, e: bool) {
+   LL|      3|    let x = a && (b && (c && (d && (e))));
+                                ^2    ^1    ^1   ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:13) to (LL:42)
+  |
+  |  Number of Conditions: 5
+  |     Condition C1 --> (LL:13)
+  |     Condition C2 --> (LL:19)
+  |     Condition C3 --> (LL:25)
+  |     Condition C4 --> (LL:31)
+  |     Condition C5 --> (LL:36)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2, C3, C4, C5    Result
+  |  1 { F,  -,  -,  -,  -  = F      }
+  |  2 { T,  F,  -,  -,  -  = F      }
+  |  3 { T,  T,  T,  T,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,3)
+  |  C2-Pair: covered: (2,3)
+  |  C3-Pair: not covered
+  |  C4-Pair: not covered
+  |  C5-Pair: not covered
+  |  MC/DC Coverage for Decision: 40.00%
+  |
+  ------------------
+   LL|      3|    black_box(x);
+   LL|      3|}
+   LL|       |
+   LL|      3|fn foo(a: bool) -> bool {
+   LL|      3|    black_box(a)
+   LL|      3|}
+   LL|       |
+   LL|      3|fn func_call(a: bool, b: bool) {
+   LL|      3|    foo(a && b);
+                           ^2
+  ------------------
+  |---> MC/DC Decision Region (LL:9) to (LL:15)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:9)
+  |     Condition C2 --> (LL:14)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  -  = F      }
+  |  2 { T,  F  = F      }
+  |  3 { T,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,3)
+  |  C2-Pair: covered: (2,3)
+  |  MC/DC Coverage for Decision: 100.00%
+  |
+  ------------------
+   LL|      3|}
+   LL|       |
+   LL|       |#[coverage(off)]
+   LL|       |fn main() {
+   LL|       |    assign_and(true, false);
+   LL|       |    assign_and(true, true);
+   LL|       |    assign_and(false, false);
+   LL|       |
+   LL|       |    assign_or(true, false);
+   LL|       |    assign_or(true, true);
+   LL|       |    assign_or(false, false);
+   LL|       |
+   LL|       |    assign_3(true, false, false);
+   LL|       |    assign_3(true, true, false);
+   LL|       |    assign_3(false, false, true);
+   LL|       |    assign_3(false, true, true);
+   LL|       |
+   LL|       |    assign_3_bis(true, false, false);
+   LL|       |    assign_3_bis(true, true, false);
+   LL|       |    assign_3_bis(false, false, true);
+   LL|       |    assign_3_bis(false, true, true);
+   LL|       |
+   LL|       |    right_comb_tree(false, false, false, true, true);
+   LL|       |    right_comb_tree(true, false, false, true, true);
+   LL|       |    right_comb_tree(true, true, true, true, true);
+   LL|       |
+   LL|       |    func_call(true, false);
+   LL|       |    func_call(true, true);
+   LL|       |    func_call(false, false);
+   LL|       |}
+
diff --git a/tests/coverage/mcdc_non_control_flow.rs b/tests/coverage/mcdc_non_control_flow.rs
new file mode 100644
index 00000000000..85c0a6c6ae5
--- /dev/null
+++ b/tests/coverage/mcdc_non_control_flow.rs
@@ -0,0 +1,72 @@
+#![feature(coverage_attribute)]
+//@ edition: 2021
+//@ min-llvm-version: 18
+//@ compile-flags: -Zcoverage-options=mcdc
+//@ llvm-cov-flags: --show-mcdc
+
+// This test ensures that boolean expressions that are not inside control flow
+// decisions are correctly instrumented.
+
+use core::hint::black_box;
+
+fn assign_and(a: bool, b: bool) {
+    let x = a && b;
+    black_box(x);
+}
+
+fn assign_or(a: bool, b: bool) {
+    let x = a || b;
+    black_box(x);
+}
+
+fn assign_3(a: bool, b: bool, c: bool) {
+    let x = a || b && c;
+    black_box(x);
+}
+
+fn assign_3_bis(a: bool, b: bool, c: bool) {
+    let x = a && b || c;
+    black_box(x);
+}
+
+fn right_comb_tree(a: bool, b: bool, c: bool, d: bool, e: bool) {
+    let x = a && (b && (c && (d && (e))));
+    black_box(x);
+}
+
+fn foo(a: bool) -> bool {
+    black_box(a)
+}
+
+fn func_call(a: bool, b: bool) {
+    foo(a && b);
+}
+
+#[coverage(off)]
+fn main() {
+    assign_and(true, false);
+    assign_and(true, true);
+    assign_and(false, false);
+
+    assign_or(true, false);
+    assign_or(true, true);
+    assign_or(false, false);
+
+    assign_3(true, false, false);
+    assign_3(true, true, false);
+    assign_3(false, false, true);
+    assign_3(false, true, true);
+
+    assign_3_bis(true, false, false);
+    assign_3_bis(true, true, false);
+    assign_3_bis(false, false, true);
+    assign_3_bis(false, true, true);
+
+    right_comb_tree(false, false, false, true, true);
+    right_comb_tree(true, false, false, true, true);
+    right_comb_tree(true, true, true, true, true);
+
+    func_call(true, false);
+    func_call(true, true);
+    func_call(false, false);
+}