tests(mcdc-coverage): Add tests for nested decision structures in mcdc_nested_if.rs

3 files changed, 506 insertions, 0 deletions

diff --git a/tests/coverage/mcdc_nested_if.cov-map b/tests/coverage/mcdc_nested_if.cov-map
new file mode 100644
index 00000000000..2f35ffad8a9
--- /dev/null
+++ b/tests/coverage/mcdc_nested_if.cov-map
@@ -0,0 +1,201 @@
+Function name: mcdc_nested_if::doubly_nested_if_in_condition
+Raw bytes (168): 0x[01, 01, 0e, 01, 05, 05, 11, 05, 11, 26, 19, 05, 11, 19, 1d, 19, 1d, 1d, 22, 26, 19, 05, 11, 11, 15, 09, 02, 0d, 37, 09, 02, 14, 01, 0f, 01, 01, 09, 28, 02, 02, 01, 08, 00, 4e, 30, 05, 02, 01, 02, 00, 00, 08, 00, 09, 30, 0d, 09, 02, 00, 00, 00, 0d, 00, 4e, 05, 00, 10, 00, 11, 28, 01, 02, 00, 10, 00, 36, 30, 11, 26, 01, 00, 02, 00, 10, 00, 11, 30, 15, 21, 02, 00, 00, 00, 15, 00, 36, 26, 00, 18, 00, 19, 28, 00, 02, 00, 18, 00, 1e, 30, 19, 22, 01, 02, 00, 00, 18, 00, 19, 19, 00, 1d, 00, 1e, 30, 1a, 1d, 02, 00, 00, 00, 1d, 00, 1e, 1a, 00, 21, 00, 25, 1f, 00, 2f, 00, 34, 2b, 00, 39, 00, 3e, 21, 00, 48, 00, 4c, 0d, 00, 4f, 02, 06, 37, 02, 0c, 02, 06, 33, 03, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 14
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 3 operands: lhs = Expression(9, Sub), rhs = Counter(6)
+- expression 4 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 5 operands: lhs = Counter(6), rhs = Counter(7)
+- expression 6 operands: lhs = Counter(6), rhs = Counter(7)
+- expression 7 operands: lhs = Counter(7), rhs = Expression(8, Sub)
+- expression 8 operands: lhs = Expression(9, Sub), rhs = Counter(6)
+- expression 9 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 10 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 11 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+- expression 12 operands: lhs = Counter(3), rhs = Expression(13, Add)
+- expression 13 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+Number of file 0 mappings: 20
+- Code(Counter(0)) at (prev + 15, 1) to (start + 1, 9)
+- MCDCDecision { bitmap_idx: 2, conditions_num: 2 } at (prev + 1, 8) to (start + 0, 78)
+- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 8) to (start + 0, 9)
+    true  = c1
+    false = (c0 - c1)
+- MCDCBranch { true: Counter(3), false: Counter(2), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 78)
+    true  = c3
+    false = c2
+- Code(Counter(1)) at (prev + 0, 16) to (start + 0, 17)
+- MCDCDecision { bitmap_idx: 1, conditions_num: 2 } at (prev + 0, 16) to (start + 0, 54)
+- MCDCBranch { true: Counter(4), false: Expression(9, Sub), condition_id: 1, true_next_id: 0, false_next_id: 2 } at (prev + 0, 16) to (start + 0, 17)
+    true  = c4
+    false = (c1 - c4)
+- MCDCBranch { true: Counter(5), false: Counter(8), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 21) to (start + 0, 54)
+    true  = c5
+    false = c8
+- Code(Expression(9, Sub)) at (prev + 0, 24) to (start + 0, 25)
+    = (c1 - c4)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 0, 24) to (start + 0, 30)
+- MCDCBranch { true: Counter(6), false: Expression(8, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 24) to (start + 0, 25)
+    true  = c6
+    false = ((c1 - c4) - c6)
+- Code(Counter(6)) at (prev + 0, 29) to (start + 0, 30)
+- MCDCBranch { true: Expression(6, Sub), false: Counter(7), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 29) to (start + 0, 30)
+    true  = (c6 - c7)
+    false = c7
+- Code(Expression(6, Sub)) at (prev + 0, 33) to (start + 0, 37)
+    = (c6 - c7)
+- Code(Expression(7, Add)) at (prev + 0, 47) to (start + 0, 52)
+    = (c7 + ((c1 - c4) - c6))
+- Code(Expression(10, Add)) at (prev + 0, 57) to (start + 0, 62)
+    = (c4 + c5)
+- Code(Counter(8)) at (prev + 0, 72) to (start + 0, 76)
+- Code(Counter(3)) at (prev + 0, 79) to (start + 2, 6)
+- Code(Expression(13, Add)) at (prev + 2, 12) to (start + 2, 6)
+    = (c2 + (c0 - c1))
+- Code(Expression(12, Add)) at (prev + 3, 1) to (start + 0, 2)
+    = (c3 + (c2 + (c0 - c1)))
+
+Function name: mcdc_nested_if::nested_if_in_condition
+Raw bytes (120): 0x[01, 01, 0b, 01, 05, 05, 11, 05, 11, 1e, 15, 05, 11, 11, 15, 1e, 15, 05, 11, 09, 02, 0d, 2b, 09, 02, 0e, 01, 07, 01, 01, 09, 28, 01, 02, 01, 08, 00, 2e, 30, 05, 02, 01, 02, 00, 00, 08, 00, 09, 30, 0d, 09, 02, 00, 00, 00, 0d, 00, 2e, 05, 00, 10, 00, 11, 28, 00, 02, 00, 10, 00, 16, 30, 11, 1e, 01, 00, 02, 00, 10, 00, 11, 1e, 00, 15, 00, 16, 30, 15, 1a, 02, 00, 00, 00, 15, 00, 16, 17, 00, 19, 00, 1d, 1a, 00, 27, 00, 2c, 0d, 00, 2f, 02, 06, 2b, 02, 0c, 02, 06, 27, 03, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 11
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 3 operands: lhs = Expression(7, Sub), rhs = Counter(5)
+- expression 4 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 5 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 6 operands: lhs = Expression(7, Sub), rhs = Counter(5)
+- expression 7 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 8 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+- expression 9 operands: lhs = Counter(3), rhs = Expression(10, Add)
+- expression 10 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+Number of file 0 mappings: 14
+- Code(Counter(0)) at (prev + 7, 1) to (start + 1, 9)
+- MCDCDecision { bitmap_idx: 1, conditions_num: 2 } at (prev + 1, 8) to (start + 0, 46)
+- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 8) to (start + 0, 9)
+    true  = c1
+    false = (c0 - c1)
+- MCDCBranch { true: Counter(3), false: Counter(2), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 46)
+    true  = c3
+    false = c2
+- Code(Counter(1)) at (prev + 0, 16) to (start + 0, 17)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 0, 16) to (start + 0, 22)
+- MCDCBranch { true: Counter(4), false: Expression(7, Sub), condition_id: 1, true_next_id: 0, false_next_id: 2 } at (prev + 0, 16) to (start + 0, 17)
+    true  = c4
+    false = (c1 - c4)
+- Code(Expression(7, Sub)) at (prev + 0, 21) to (start + 0, 22)
+    = (c1 - c4)
+- MCDCBranch { true: Counter(5), false: Expression(6, Sub), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 21) to (start + 0, 22)
+    true  = c5
+    false = ((c1 - c4) - c5)
+- Code(Expression(5, Add)) at (prev + 0, 25) to (start + 0, 29)
+    = (c4 + c5)
+- Code(Expression(6, Sub)) at (prev + 0, 39) to (start + 0, 44)
+    = ((c1 - c4) - c5)
+- Code(Counter(3)) at (prev + 0, 47) to (start + 2, 6)
+- Code(Expression(10, Add)) at (prev + 2, 12) to (start + 2, 6)
+    = (c2 + (c0 - c1))
+- Code(Expression(9, Add)) at (prev + 3, 1) to (start + 0, 2)
+    = (c3 + (c2 + (c0 - c1)))
+
+Function name: mcdc_nested_if::nested_in_then_block_in_condition
+Raw bytes (176): 0x[01, 01, 12, 01, 05, 05, 11, 05, 11, 3a, 15, 05, 11, 11, 15, 33, 19, 11, 15, 19, 1d, 19, 1d, 1d, 2e, 33, 19, 11, 15, 3a, 15, 05, 11, 09, 02, 0d, 47, 09, 02, 14, 01, 22, 01, 01, 09, 28, 02, 02, 01, 08, 00, 4b, 30, 05, 02, 01, 02, 00, 00, 08, 00, 09, 30, 0d, 09, 02, 00, 00, 00, 0d, 00, 4b, 05, 00, 10, 00, 11, 28, 00, 02, 00, 10, 00, 16, 30, 11, 3a, 01, 00, 02, 00, 10, 00, 11, 3a, 00, 15, 00, 16, 30, 15, 36, 02, 00, 00, 00, 15, 00, 16, 33, 00, 1c, 00, 1d, 28, 01, 02, 00, 1c, 00, 22, 30, 19, 2e, 01, 02, 00, 00, 1c, 00, 1d, 19, 00, 21, 00, 22, 30, 26, 1d, 02, 00, 00, 00, 21, 00, 22, 26, 00, 25, 00, 29, 2b, 00, 33, 00, 38, 36, 00, 44, 00, 49, 0d, 00, 4c, 02, 06, 47, 02, 0c, 02, 06, 43, 03, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 18
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 3 operands: lhs = Expression(14, Sub), rhs = Counter(5)
+- expression 4 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 5 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 6 operands: lhs = Expression(12, Add), rhs = Counter(6)
+- expression 7 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 8 operands: lhs = Counter(6), rhs = Counter(7)
+- expression 9 operands: lhs = Counter(6), rhs = Counter(7)
+- expression 10 operands: lhs = Counter(7), rhs = Expression(11, Sub)
+- expression 11 operands: lhs = Expression(12, Add), rhs = Counter(6)
+- expression 12 operands: lhs = Counter(4), rhs = Counter(5)
+- expression 13 operands: lhs = Expression(14, Sub), rhs = Counter(5)
+- expression 14 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 15 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+- expression 16 operands: lhs = Counter(3), rhs = Expression(17, Add)
+- expression 17 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+Number of file 0 mappings: 20
+- Code(Counter(0)) at (prev + 34, 1) to (start + 1, 9)
+- MCDCDecision { bitmap_idx: 2, conditions_num: 2 } at (prev + 1, 8) to (start + 0, 75)
+- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 8) to (start + 0, 9)
+    true  = c1
+    false = (c0 - c1)
+- MCDCBranch { true: Counter(3), false: Counter(2), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 75)
+    true  = c3
+    false = c2
+- Code(Counter(1)) at (prev + 0, 16) to (start + 0, 17)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 0, 16) to (start + 0, 22)
+- MCDCBranch { true: Counter(4), false: Expression(14, Sub), condition_id: 1, true_next_id: 0, false_next_id: 2 } at (prev + 0, 16) to (start + 0, 17)
+    true  = c4
+    false = (c1 - c4)
+- Code(Expression(14, Sub)) at (prev + 0, 21) to (start + 0, 22)
+    = (c1 - c4)
+- MCDCBranch { true: Counter(5), false: Expression(13, Sub), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 21) to (start + 0, 22)
+    true  = c5
+    false = ((c1 - c4) - c5)
+- Code(Expression(12, Add)) at (prev + 0, 28) to (start + 0, 29)
+    = (c4 + c5)
+- MCDCDecision { bitmap_idx: 1, conditions_num: 2 } at (prev + 0, 28) to (start + 0, 34)
+- MCDCBranch { true: Counter(6), false: Expression(11, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 28) to (start + 0, 29)
+    true  = c6
+    false = ((c4 + c5) - c6)
+- Code(Counter(6)) at (prev + 0, 33) to (start + 0, 34)
+- MCDCBranch { true: Expression(9, Sub), false: Counter(7), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 33) to (start + 0, 34)
+    true  = (c6 - c7)
+    false = c7
+- Code(Expression(9, Sub)) at (prev + 0, 37) to (start + 0, 41)
+    = (c6 - c7)
+- Code(Expression(10, Add)) at (prev + 0, 51) to (start + 0, 56)
+    = (c7 + ((c4 + c5) - c6))
+- Code(Expression(13, Sub)) at (prev + 0, 68) to (start + 0, 73)
+    = ((c1 - c4) - c5)
+- Code(Counter(3)) at (prev + 0, 76) to (start + 2, 6)
+- Code(Expression(17, Add)) at (prev + 2, 12) to (start + 2, 6)
+    = (c2 + (c0 - c1))
+- Code(Expression(16, Add)) at (prev + 3, 1) to (start + 0, 2)
+    = (c3 + (c2 + (c0 - c1)))
+
+Function name: mcdc_nested_if::nested_single_condition_decision
+Raw bytes (85): 0x[01, 01, 06, 01, 05, 05, 11, 05, 11, 09, 02, 0d, 17, 09, 02, 0b, 01, 17, 01, 04, 09, 28, 00, 02, 04, 08, 00, 29, 30, 05, 02, 01, 02, 00, 00, 08, 00, 09, 30, 0d, 09, 02, 00, 00, 00, 0d, 00, 29, 05, 00, 10, 00, 11, 20, 11, 0a, 00, 10, 00, 11, 11, 00, 14, 00, 19, 0a, 00, 23, 00, 27, 0d, 00, 2a, 02, 06, 17, 02, 0c, 02, 06, 13, 03, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 6
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 2 operands: lhs = Counter(1), rhs = Counter(4)
+- expression 3 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+- expression 4 operands: lhs = Counter(3), rhs = Expression(5, Add)
+- expression 5 operands: lhs = Counter(2), rhs = Expression(0, Sub)
+Number of file 0 mappings: 11
+- Code(Counter(0)) at (prev + 23, 1) to (start + 4, 9)
+- MCDCDecision { bitmap_idx: 0, conditions_num: 2 } at (prev + 4, 8) to (start + 0, 41)
+- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 2, false_next_id: 0 } at (prev + 0, 8) to (start + 0, 9)
+    true  = c1
+    false = (c0 - c1)
+- MCDCBranch { true: Counter(3), false: Counter(2), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 41)
+    true  = c3
+    false = c2
+- Code(Counter(1)) at (prev + 0, 16) to (start + 0, 17)
+- Branch { true: Counter(4), false: Expression(2, Sub) } at (prev + 0, 16) to (start + 0, 17)
+    true  = c4
+    false = (c1 - c4)
+- Code(Counter(4)) at (prev + 0, 20) to (start + 0, 25)
+- Code(Expression(2, Sub)) at (prev + 0, 35) to (start + 0, 39)
+    = (c1 - c4)
+- Code(Counter(3)) at (prev + 0, 42) to (start + 2, 6)
+- Code(Expression(5, Add)) at (prev + 2, 12) to (start + 2, 6)
+    = (c2 + (c0 - c1))
+- Code(Expression(4, Add)) at (prev + 3, 1) to (start + 0, 2)
+    = (c3 + (c2 + (c0 - c1)))
+
diff --git a/tests/coverage/mcdc_nested_if.coverage b/tests/coverage/mcdc_nested_if.coverage
new file mode 100644
index 00000000000..19529cd6aa4
--- /dev/null
+++ b/tests/coverage/mcdc_nested_if.coverage
@@ -0,0 +1,235 @@
+   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|      4|fn nested_if_in_condition(a: bool, b: bool, c: bool) {
+   LL|      4|    if a && if b || c { true } else { false } {
+                             ^3   ^2  ^2            ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:8) to (LL:46)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:8)
+  |     Condition C2 --> (LL:13)
+  |
+  |  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%
+  |
+  |---> MC/DC Decision Region (LL:16) to (LL:22)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:16)
+  |     Condition C2 --> (LL:21)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  F  = F      }
+  |  2 { T,  -  = T      }
+  |  3 { F,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: covered: (1,3)
+  |  MC/DC Coverage for Decision: 100.00%
+  |
+  ------------------
+   LL|      2|        say("yes");
+   LL|      2|    } else {
+   LL|      2|        say("no");
+   LL|      2|    }
+   LL|      4|}
+   LL|       |
+   LL|      4|fn doubly_nested_if_in_condition(a: bool, b: bool, c: bool, d: bool) {
+   LL|      4|    if a && if b || if c && d { true } else { false } { false } else { true } {
+                             ^3      ^2   ^1  ^1            ^1        ^2             ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:8) to (LL:78)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:8)
+  |     Condition C2 --> (LL:13)
+  |
+  |  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%
+  |
+  |---> MC/DC Decision Region (LL:16) to (LL:54)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:16)
+  |     Condition C2 --> (LL:21)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  F  = F      }
+  |  2 { T,  -  = T      }
+  |  3 { F,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: covered: (1,3)
+  |  MC/DC Coverage for Decision: 100.00%
+  |
+  |---> MC/DC Decision Region (LL:24) to (LL:30)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:24)
+  |     Condition C2 --> (LL:29)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  -  = F      }
+  |  2 { T,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: not covered
+  |  MC/DC Coverage for Decision: 50.00%
+  |
+  ------------------
+   LL|      1|        say("yes");
+   LL|      3|    } else {
+   LL|      3|        say("no");
+   LL|      3|    }
+   LL|      4|}
+   LL|       |
+   LL|      3|fn nested_single_condition_decision(a: bool, b: bool) {
+   LL|      3|    // Decision with only 1 decision should not be instrumented by MCDC because
+   LL|      3|    // branch-coverage is equivalent to MCDC coverage in this case, and we don't
+   LL|      3|    // want to waste bitmap space for this.
+   LL|      3|    if a && if b { false } else { true } {
+                             ^2  ^1             ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:8) to (LL:41)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:8)
+  |     Condition C2 --> (LL:13)
+  |
+  |  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|      1|        say("yes");
+   LL|      2|    } else {
+   LL|      2|        say("no");
+   LL|      2|    }
+   LL|      3|}
+   LL|       |
+   LL|      7|fn nested_in_then_block_in_condition(a: bool, b: bool, c: bool, d: bool, e: bool) {
+   LL|      7|    if a && if b || c { if d && e { true } else { false } } else { false } {
+                             ^6   ^5     ^5   ^2  ^1            ^4               ^1
+  ------------------
+  |---> MC/DC Decision Region (LL:8) to (LL:75)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:8)
+  |     Condition C2 --> (LL:13)
+  |
+  |  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%
+  |
+  |---> MC/DC Decision Region (LL:16) to (LL:22)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:16)
+  |     Condition C2 --> (LL:21)
+  |
+  |  Executed MC/DC Test Vectors:
+  |
+  |     C1, C2    Result
+  |  1 { F,  F  = F      }
+  |  2 { T,  -  = T      }
+  |  3 { F,  T  = T      }
+  |
+  |  C1-Pair: covered: (1,2)
+  |  C2-Pair: covered: (1,3)
+  |  MC/DC Coverage for Decision: 100.00%
+  |
+  |---> MC/DC Decision Region (LL:28) to (LL:34)
+  |
+  |  Number of Conditions: 2
+  |     Condition C1 --> (LL:28)
+  |     Condition C2 --> (LL:33)
+  |
+  |  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|      1|        say("yes");
+   LL|      6|    } else {
+   LL|      6|        say("no");
+   LL|      6|    }
+   LL|      7|}
+   LL|       |
+   LL|       |#[coverage(off)]
+   LL|       |fn main() {
+   LL|       |    nested_if_in_condition(true, false, false);
+   LL|       |    nested_if_in_condition(true, true, true);
+   LL|       |    nested_if_in_condition(true, false, true);
+   LL|       |    nested_if_in_condition(false, true, true);
+   LL|       |
+   LL|       |    doubly_nested_if_in_condition(true, false, false, true);
+   LL|       |    doubly_nested_if_in_condition(true, true, true, true);
+   LL|       |    doubly_nested_if_in_condition(true, false, true, true);
+   LL|       |    doubly_nested_if_in_condition(false, true, true, true);
+   LL|       |
+   LL|       |    nested_single_condition_decision(true, true);
+   LL|       |    nested_single_condition_decision(true, false);
+   LL|       |    nested_single_condition_decision(false, false);
+   LL|       |
+   LL|       |    nested_in_then_block_in_condition(false, false, false, false, false);
+   LL|       |    nested_in_then_block_in_condition(true, false, false, false, false);
+   LL|       |    nested_in_then_block_in_condition(true, true, false, false, false);
+   LL|       |    nested_in_then_block_in_condition(true, false, true, false, false);
+   LL|       |    nested_in_then_block_in_condition(true, false, true, true, false);
+   LL|       |    nested_in_then_block_in_condition(true, false, true, false, true);
+   LL|       |    nested_in_then_block_in_condition(true, false, true, true, true);
+   LL|       |}
+   LL|       |
+   LL|       |#[coverage(off)]
+   LL|       |fn say(message: &str) {
+   LL|       |    core::hint::black_box(message);
+   LL|       |}
+
diff --git a/tests/coverage/mcdc_nested_if.rs b/tests/coverage/mcdc_nested_if.rs
new file mode 100644
index 00000000000..3d869771f75
--- /dev/null
+++ b/tests/coverage/mcdc_nested_if.rs
@@ -0,0 +1,70 @@
+#![feature(coverage_attribute)]
+//@ edition: 2021
+//@ min-llvm-version: 18
+//@ compile-flags: -Zcoverage-options=mcdc
+//@ llvm-cov-flags: --show-mcdc
+
+fn nested_if_in_condition(a: bool, b: bool, c: bool) {
+    if a && if b || c { true } else { false } {
+        say("yes");
+    } else {
+        say("no");
+    }
+}
+
+fn doubly_nested_if_in_condition(a: bool, b: bool, c: bool, d: bool) {
+    if a && if b || if c && d { true } else { false } { false } else { true } {
+        say("yes");
+    } else {
+        say("no");
+    }
+}
+
+fn nested_single_condition_decision(a: bool, b: bool) {
+    // Decision with only 1 decision should not be instrumented by MCDC because
+    // branch-coverage is equivalent to MCDC coverage in this case, and we don't
+    // want to waste bitmap space for this.
+    if a && if b { false } else { true } {
+        say("yes");
+    } else {
+        say("no");
+    }
+}
+
+fn nested_in_then_block_in_condition(a: bool, b: bool, c: bool, d: bool, e: bool) {
+    if a && if b || c { if d && e { true } else { false } } else { false } {
+        say("yes");
+    } else {
+        say("no");
+    }
+}
+
+#[coverage(off)]
+fn main() {
+    nested_if_in_condition(true, false, false);
+    nested_if_in_condition(true, true, true);
+    nested_if_in_condition(true, false, true);
+    nested_if_in_condition(false, true, true);
+
+    doubly_nested_if_in_condition(true, false, false, true);
+    doubly_nested_if_in_condition(true, true, true, true);
+    doubly_nested_if_in_condition(true, false, true, true);
+    doubly_nested_if_in_condition(false, true, true, true);
+
+    nested_single_condition_decision(true, true);
+    nested_single_condition_decision(true, false);
+    nested_single_condition_decision(false, false);
+
+    nested_in_then_block_in_condition(false, false, false, false, false);
+    nested_in_then_block_in_condition(true, false, false, false, false);
+    nested_in_then_block_in_condition(true, true, false, false, false);
+    nested_in_then_block_in_condition(true, false, true, false, false);
+    nested_in_then_block_in_condition(true, false, true, true, false);
+    nested_in_then_block_in_condition(true, false, true, false, true);
+    nested_in_then_block_in_condition(true, false, true, true, true);
+}
+
+#[coverage(off)]
+fn say(message: &str) {
+    core::hint::black_box(message);
+}