Rollup merge of #125700 - Zalathar:limit-overflow, r=nnethercote
coverage: Avoid overflow when the MC/DC condition limit is exceeded Fix for the test failure seen in https://github.com/rust-lang/rust/pull/124571#issuecomment-2099620869. If we perform this subtraction first, it can sometimes overflow to -1 before the addition can bring its value back to 0. That behaviour seems to be benign, but it nevertheless causes test failures in compiler configurations that check for overflow. ``@rustbot`` label +A-code-coverage
This commit is contained in:
Matthias Krüger
GitHub
commit
9a61146765
@ -217,12 +217,13 @@ pub fn visit_evaluated_condition(
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}
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}
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_ => {
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_ => {
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// Do not generate mcdc mappings and statements for decisions with too many conditions.
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// Do not generate mcdc mappings and statements for decisions with too many conditions.
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let rebase_idx = self.branch_spans.len() - decision.conditions_num + 1;
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// Therefore, first erase the condition info of the (N-1) previous branch spans.
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let rebase_idx = self.branch_spans.len() - (decision.conditions_num - 1);
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for branch in &mut self.branch_spans[rebase_idx..] {
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for branch in &mut self.branch_spans[rebase_idx..] {
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branch.condition_info = None;
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branch.condition_info = None;
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}
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}
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// ConditionInfo of this branch shall also be reset.
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// Then, erase this last branch span's info too, for a total of N.
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condition_info = None;
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condition_info = None;
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tcx.dcx().emit_warn(MCDCExceedsConditionNumLimit {
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tcx.dcx().emit_warn(MCDCExceedsConditionNumLimit {
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162
tests/coverage/mcdc/condition-limit.cov-map
Normal file
162
tests/coverage/mcdc/condition-limit.cov-map
Normal file
@ -0,0 +1,162 @@
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Function name: condition_limit::bad
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Raw bytes (204): 0x[01, 01, 2c, 01, 05, 05, 1d, 05, 1d, 7a, 19, 05, 1d, 7a, 19, 05, 1d, 76, 15, 7a, 19, 05, 1d, 76, 15, 7a, 19, 05, 1d, 72, 11, 76, 15, 7a, 19, 05, 1d, 72, 11, 76, 15, 7a, 19, 05, 1d, 6e, 0d, 72, 11, 76, 15, 7a, 19, 05, 1d, 6e, 0d, 72, 11, 76, 15, 7a, 19, 05, 1d, 9f, 01, 02, a3, 01, 1d, a7, 01, 19, ab, 01, 15, af, 01, 11, 09, 0d, 21, 9b, 01, 9f, 01, 02, a3, 01, 1d, a7, 01, 19, ab, 01, 15, af, 01, 11, 09, 0d, 11, 01, 14, 01, 03, 09, 20, 05, 02, 03, 08, 00, 09, 05, 00, 0d, 00, 0e, 20, 7a, 1d, 00, 0d, 00, 0e, 7a, 00, 12, 00, 13, 20, 76, 19, 00, 12, 00, 13, 76, 00, 17, 00, 18, 20, 72, 15, 00, 17, 00, 18, 72, 00, 1c, 00, 1d, 20, 6e, 11, 00, 1c, 00, 1d, 6e, 00, 21, 00, 22, 20, 6a, 0d, 00, 21, 00, 22, 6a, 00, 26, 00, 27, 20, 21, 09, 00, 26, 00, 27, 21, 00, 28, 02, 06, 9b, 01, 02, 06, 00, 07, 97, 01, 01, 01, 00, 02]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 44
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- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
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- expression 1 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 2 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 3 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 4 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 5 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 6 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 7 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 8 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 9 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 10 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 11 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 12 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 13 operands: lhs = Expression(28, Sub), rhs = Counter(4)
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- expression 14 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 15 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 16 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 17 operands: lhs = Expression(28, Sub), rhs = Counter(4)
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- expression 18 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 19 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 20 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 21 operands: lhs = Expression(27, Sub), rhs = Counter(3)
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- expression 22 operands: lhs = Expression(28, Sub), rhs = Counter(4)
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- expression 23 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 24 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 25 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 26 operands: lhs = Expression(27, Sub), rhs = Counter(3)
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- expression 27 operands: lhs = Expression(28, Sub), rhs = Counter(4)
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- expression 28 operands: lhs = Expression(29, Sub), rhs = Counter(5)
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- expression 29 operands: lhs = Expression(30, Sub), rhs = Counter(6)
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- expression 30 operands: lhs = Counter(1), rhs = Counter(7)
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- expression 31 operands: lhs = Expression(39, Add), rhs = Expression(0, Sub)
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- expression 32 operands: lhs = Expression(40, Add), rhs = Counter(7)
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- expression 33 operands: lhs = Expression(41, Add), rhs = Counter(6)
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- expression 34 operands: lhs = Expression(42, Add), rhs = Counter(5)
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- expression 35 operands: lhs = Expression(43, Add), rhs = Counter(4)
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- expression 36 operands: lhs = Counter(2), rhs = Counter(3)
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- expression 37 operands: lhs = Counter(8), rhs = Expression(38, Add)
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- expression 38 operands: lhs = Expression(39, Add), rhs = Expression(0, Sub)
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- expression 39 operands: lhs = Expression(40, Add), rhs = Counter(7)
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- expression 40 operands: lhs = Expression(41, Add), rhs = Counter(6)
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- expression 41 operands: lhs = Expression(42, Add), rhs = Counter(5)
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- expression 42 operands: lhs = Expression(43, Add), rhs = Counter(4)
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- expression 43 operands: lhs = Counter(2), rhs = Counter(3)
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Number of file 0 mappings: 17
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- Code(Counter(0)) at (prev + 20, 1) to (start + 3, 9)
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- Branch { true: Counter(1), false: Expression(0, Sub) } at (prev + 3, 8) to (start + 0, 9)
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true = c1
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false = (c0 - c1)
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- Code(Counter(1)) at (prev + 0, 13) to (start + 0, 14)
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- Branch { true: Expression(30, Sub), false: Counter(7) } at (prev + 0, 13) to (start + 0, 14)
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true = (c1 - c7)
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false = c7
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- Code(Expression(30, Sub)) at (prev + 0, 18) to (start + 0, 19)
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= (c1 - c7)
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- Branch { true: Expression(29, Sub), false: Counter(6) } at (prev + 0, 18) to (start + 0, 19)
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true = ((c1 - c7) - c6)
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false = c6
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- Code(Expression(29, Sub)) at (prev + 0, 23) to (start + 0, 24)
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= ((c1 - c7) - c6)
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- Branch { true: Expression(28, Sub), false: Counter(5) } at (prev + 0, 23) to (start + 0, 24)
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true = (((c1 - c7) - c6) - c5)
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false = c5
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- Code(Expression(28, Sub)) at (prev + 0, 28) to (start + 0, 29)
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= (((c1 - c7) - c6) - c5)
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- Branch { true: Expression(27, Sub), false: Counter(4) } at (prev + 0, 28) to (start + 0, 29)
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true = ((((c1 - c7) - c6) - c5) - c4)
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false = c4
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- Code(Expression(27, Sub)) at (prev + 0, 33) to (start + 0, 34)
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= ((((c1 - c7) - c6) - c5) - c4)
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- Branch { true: Expression(26, Sub), false: Counter(3) } at (prev + 0, 33) to (start + 0, 34)
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true = (((((c1 - c7) - c6) - c5) - c4) - c3)
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false = c3
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- Code(Expression(26, Sub)) at (prev + 0, 38) to (start + 0, 39)
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= (((((c1 - c7) - c6) - c5) - c4) - c3)
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- Branch { true: Counter(8), false: Counter(2) } at (prev + 0, 38) to (start + 0, 39)
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true = c8
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false = c2
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- Code(Counter(8)) at (prev + 0, 40) to (start + 2, 6)
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- Code(Expression(38, Add)) at (prev + 2, 6) to (start + 0, 7)
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= ((((((c2 + c3) + c4) + c5) + c6) + c7) + (c0 - c1))
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- Code(Expression(37, Add)) at (prev + 1, 1) to (start + 0, 2)
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= (c8 + ((((((c2 + c3) + c4) + c5) + c6) + c7) + (c0 - c1)))
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Function name: condition_limit::good
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Raw bytes (180): 0x[01, 01, 20, 01, 05, 05, 19, 05, 19, 52, 15, 05, 19, 52, 15, 05, 19, 4e, 11, 52, 15, 05, 19, 4e, 11, 52, 15, 05, 19, 4a, 0d, 4e, 11, 52, 15, 05, 19, 4a, 0d, 4e, 11, 52, 15, 05, 19, 73, 02, 77, 19, 7b, 15, 7f, 11, 09, 0d, 1d, 6f, 73, 02, 77, 19, 7b, 15, 7f, 11, 09, 0d, 10, 01, 0c, 01, 03, 09, 28, 00, 06, 03, 08, 00, 22, 30, 05, 02, 01, 06, 00, 00, 08, 00, 09, 05, 00, 0d, 00, 0e, 30, 52, 19, 06, 05, 00, 00, 0d, 00, 0e, 52, 00, 12, 00, 13, 30, 4e, 15, 05, 04, 00, 00, 12, 00, 13, 4e, 00, 17, 00, 18, 30, 4a, 11, 04, 03, 00, 00, 17, 00, 18, 4a, 00, 1c, 00, 1d, 30, 46, 0d, 03, 02, 00, 00, 1c, 00, 1d, 46, 00, 21, 00, 22, 30, 1d, 09, 02, 00, 00, 00, 21, 00, 22, 1d, 00, 23, 02, 06, 6f, 02, 06, 00, 07, 6b, 01, 01, 00, 02]
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Number of files: 1
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- file 0 => global file 1
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Number of expressions: 32
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- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
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- expression 1 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 2 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 3 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 4 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 5 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 6 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 7 operands: lhs = Expression(19, Sub), rhs = Counter(4)
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- expression 8 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 9 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 10 operands: lhs = Expression(19, Sub), rhs = Counter(4)
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- expression 11 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 12 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 13 operands: lhs = Expression(18, Sub), rhs = Counter(3)
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- expression 14 operands: lhs = Expression(19, Sub), rhs = Counter(4)
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- expression 15 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 16 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 17 operands: lhs = Expression(18, Sub), rhs = Counter(3)
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- expression 18 operands: lhs = Expression(19, Sub), rhs = Counter(4)
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- expression 19 operands: lhs = Expression(20, Sub), rhs = Counter(5)
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- expression 20 operands: lhs = Counter(1), rhs = Counter(6)
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- expression 21 operands: lhs = Expression(28, Add), rhs = Expression(0, Sub)
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- expression 22 operands: lhs = Expression(29, Add), rhs = Counter(6)
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- expression 23 operands: lhs = Expression(30, Add), rhs = Counter(5)
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- expression 24 operands: lhs = Expression(31, Add), rhs = Counter(4)
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- expression 25 operands: lhs = Counter(2), rhs = Counter(3)
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- expression 26 operands: lhs = Counter(7), rhs = Expression(27, Add)
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- expression 27 operands: lhs = Expression(28, Add), rhs = Expression(0, Sub)
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- expression 28 operands: lhs = Expression(29, Add), rhs = Counter(6)
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- expression 29 operands: lhs = Expression(30, Add), rhs = Counter(5)
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- expression 30 operands: lhs = Expression(31, Add), rhs = Counter(4)
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- expression 31 operands: lhs = Counter(2), rhs = Counter(3)
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Number of file 0 mappings: 16
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- Code(Counter(0)) at (prev + 12, 1) to (start + 3, 9)
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- MCDCDecision { bitmap_idx: 0, conditions_num: 6 } at (prev + 3, 8) to (start + 0, 34)
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- MCDCBranch { true: Counter(1), false: Expression(0, Sub), condition_id: 1, true_next_id: 6, false_next_id: 0 } at (prev + 0, 8) to (start + 0, 9)
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true = c1
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false = (c0 - c1)
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- Code(Counter(1)) at (prev + 0, 13) to (start + 0, 14)
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- MCDCBranch { true: Expression(20, Sub), false: Counter(6), condition_id: 6, true_next_id: 5, false_next_id: 0 } at (prev + 0, 13) to (start + 0, 14)
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true = (c1 - c6)
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false = c6
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- Code(Expression(20, Sub)) at (prev + 0, 18) to (start + 0, 19)
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= (c1 - c6)
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- MCDCBranch { true: Expression(19, Sub), false: Counter(5), condition_id: 5, true_next_id: 4, false_next_id: 0 } at (prev + 0, 18) to (start + 0, 19)
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true = ((c1 - c6) - c5)
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false = c5
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- Code(Expression(19, Sub)) at (prev + 0, 23) to (start + 0, 24)
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= ((c1 - c6) - c5)
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- MCDCBranch { true: Expression(18, Sub), false: Counter(4), condition_id: 4, true_next_id: 3, false_next_id: 0 } at (prev + 0, 23) to (start + 0, 24)
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true = (((c1 - c6) - c5) - c4)
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false = c4
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- Code(Expression(18, Sub)) at (prev + 0, 28) to (start + 0, 29)
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= (((c1 - c6) - c5) - c4)
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- MCDCBranch { true: Expression(17, Sub), false: Counter(3), condition_id: 3, true_next_id: 2, false_next_id: 0 } at (prev + 0, 28) to (start + 0, 29)
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true = ((((c1 - c6) - c5) - c4) - c3)
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false = c3
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- Code(Expression(17, Sub)) at (prev + 0, 33) to (start + 0, 34)
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|
= ((((c1 - c6) - c5) - c4) - c3)
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- MCDCBranch { true: Counter(7), false: Counter(2), condition_id: 2, true_next_id: 0, false_next_id: 0 } at (prev + 0, 33) to (start + 0, 34)
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true = c7
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false = c2
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- Code(Counter(7)) at (prev + 0, 35) to (start + 2, 6)
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- Code(Expression(27, Add)) at (prev + 2, 6) to (start + 0, 7)
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= (((((c2 + c3) + c4) + c5) + c6) + (c0 - c1))
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- Code(Expression(26, Add)) at (prev + 1, 1) to (start + 0, 2)
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= (c7 + (((((c2 + c3) + c4) + c5) + c6) + (c0 - c1)))
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76
tests/coverage/mcdc/condition-limit.coverage
Normal file
76
tests/coverage/mcdc/condition-limit.coverage
Normal file
@ -0,0 +1,76 @@
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LL| |#![feature(coverage_attribute)]
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LL| |//@ edition: 2021
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LL| |//@ min-llvm-version: 18
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LL| |//@ compile-flags: -Zcoverage-options=mcdc
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LL| |//@ llvm-cov-flags: --show-branches=count --show-mcdc
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LL| |
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LL| |// Check that MC/DC instrumentation can gracefully handle conditions that
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LL| |// exceed LLVM's limit of 6 conditions per decision.
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|
LL| |//
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LL| |// (The limit is enforced in `compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs`.)
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LL| |
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LL| 1|fn good() {
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|
LL| 1| // With only 6 conditions, perform full MC/DC instrumentation.
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LL| 1| let [a, b, c, d, e, f] = <[bool; 6]>::default();
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LL| 1| if a && b && c && d && e && f {
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^0 ^0 ^0 ^0 ^0
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|
------------------
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| Branch (LL:8): [True: 0, False: 1]
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| Branch (LL:13): [True: 0, False: 0]
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| Branch (LL:18): [True: 0, False: 0]
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| Branch (LL:23): [True: 0, False: 0]
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| Branch (LL:28): [True: 0, False: 0]
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| Branch (LL:33): [True: 0, False: 0]
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|
------------------
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|---> MC/DC Decision Region (LL:8) to (LL:34)
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|
|
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| Number of Conditions: 6
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|
| Condition C1 --> (LL:8)
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| Condition C2 --> (LL:13)
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| Condition C3 --> (LL:18)
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| Condition C4 --> (LL:23)
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| Condition C5 --> (LL:28)
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| Condition C6 --> (LL:33)
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|
|
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| Executed MC/DC Test Vectors:
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|
|
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| C1, C2, C3, C4, C5, C6 Result
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|
| 1 { F, -, -, -, -, - = F }
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|
|
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|
| C1-Pair: not covered
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|
| C2-Pair: not covered
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|
| C3-Pair: not covered
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|
| C4-Pair: not covered
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|
| C5-Pair: not covered
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|
| C6-Pair: not covered
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|
| MC/DC Coverage for Decision: 0.00%
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|
|
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|
------------------
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LL| 0| core::hint::black_box("hello");
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|
LL| 1| }
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|
LL| 1|}
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|
LL| |
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|
LL| 1|fn bad() {
|
||||||
|
LL| 1| // With 7 conditions, fall back to branch instrumentation only.
|
||||||
|
LL| 1| let [a, b, c, d, e, f, g] = <[bool; 7]>::default();
|
||||||
|
LL| 1| if a && b && c && d && e && f && g {
|
||||||
|
^0 ^0 ^0 ^0 ^0 ^0
|
||||||
|
------------------
|
||||||
|
| Branch (LL:8): [True: 0, False: 1]
|
||||||
|
| Branch (LL:13): [True: 0, False: 0]
|
||||||
|
| Branch (LL:18): [True: 0, False: 0]
|
||||||
|
| Branch (LL:23): [True: 0, False: 0]
|
||||||
|
| Branch (LL:28): [True: 0, False: 0]
|
||||||
|
| Branch (LL:33): [True: 0, False: 0]
|
||||||
|
| Branch (LL:38): [True: 0, False: 0]
|
||||||
|
------------------
|
||||||
|
LL| 0| core::hint::black_box("hello");
|
||||||
|
LL| 1| }
|
||||||
|
LL| 1|}
|
||||||
|
LL| |
|
||||||
|
LL| |#[coverage(off)]
|
||||||
|
LL| |fn main() {
|
||||||
|
LL| | good();
|
||||||
|
LL| | bad();
|
||||||
|
LL| |}
|
||||||
|
|
||||||
32
tests/coverage/mcdc/condition-limit.rs
Normal file
32
tests/coverage/mcdc/condition-limit.rs
Normal file
@ -0,0 +1,32 @@
|
|||||||
|
#![feature(coverage_attribute)]
|
||||||
|
//@ edition: 2021
|
||||||
|
//@ min-llvm-version: 18
|
||||||
|
//@ compile-flags: -Zcoverage-options=mcdc
|
||||||
|
//@ llvm-cov-flags: --show-branches=count --show-mcdc
|
||||||
|
|
||||||
|
// Check that MC/DC instrumentation can gracefully handle conditions that
|
||||||
|
// exceed LLVM's limit of 6 conditions per decision.
|
||||||
|
//
|
||||||
|
// (The limit is enforced in `compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs`.)
|
||||||
|
|
||||||
|
fn good() {
|
||||||
|
// With only 6 conditions, perform full MC/DC instrumentation.
|
||||||
|
let [a, b, c, d, e, f] = <[bool; 6]>::default();
|
||||||
|
if a && b && c && d && e && f {
|
||||||
|
core::hint::black_box("hello");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
fn bad() {
|
||||||
|
// With 7 conditions, fall back to branch instrumentation only.
|
||||||
|
let [a, b, c, d, e, f, g] = <[bool; 7]>::default();
|
||||||
|
if a && b && c && d && e && f && g {
|
||||||
|
core::hint::black_box("hello");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
#[coverage(off)]
|
||||||
|
fn main() {
|
||||||
|
good();
|
||||||
|
bad();
|
||||||
|
}
|
||||||
@ -0,0 +1,8 @@
|
|||||||
|
warning: Conditions number of the decision (7) exceeds limit (6). MCDC analysis will not count this expression.
|
||||||
|
--> $DIR/mcdc-condition-limit.rs:29:8
|
||||||
|
|
|
||||||
|
LL | if a && b && c && d && e && f && g {
|
||||||
|
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||||
|
|
||||||
|
warning: 1 warning emitted
|
||||||
|
|
||||||
32
tests/ui/instrument-coverage/mcdc-condition-limit.rs
Normal file
32
tests/ui/instrument-coverage/mcdc-condition-limit.rs
Normal file
@ -0,0 +1,32 @@
|
|||||||
|
//@ edition: 2021
|
||||||
|
//@ min-llvm-version: 18
|
||||||
|
//@ revisions: good bad
|
||||||
|
//@ check-pass
|
||||||
|
//@ compile-flags: -Cinstrument-coverage -Zcoverage-options=mcdc -Zno-profiler-runtime
|
||||||
|
|
||||||
|
// Check that we emit some kind of diagnostic when MC/DC instrumentation sees
|
||||||
|
// code that exceeds the limit of 6 conditions per decision, and falls back
|
||||||
|
// to only instrumenting that code for branch coverage.
|
||||||
|
//
|
||||||
|
// See also `tests/coverage/mcdc/condition-limit.rs`, which tests the actual
|
||||||
|
// effect on instrumentation.
|
||||||
|
//
|
||||||
|
// (The limit is enforced in `compiler/rustc_mir_build/src/build/coverageinfo/mcdc.rs`.)
|
||||||
|
|
||||||
|
#[cfg(good)]
|
||||||
|
fn main() {
|
||||||
|
// 6 conditions is OK, so no diagnostic.
|
||||||
|
let [a, b, c, d, e, f] = <[bool; 6]>::default();
|
||||||
|
if a && b && c && d && e && f {
|
||||||
|
core::hint::black_box("hello");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
#[cfg(bad)]
|
||||||
|
fn main() {
|
||||||
|
// 7 conditions is too many, so issue a diagnostic.
|
||||||
|
let [a, b, c, d, e, f, g] = <[bool; 7]>::default();
|
||||||
|
if a && b && c && d && e && f && g { //[bad]~ WARNING Conditions number of the decision
|
||||||
|
core::hint::black_box("hello");
|
||||||
|
}
|
||||||
|
}
|
||||||
Loading…
Reference in New Issue
Block a user