| Issue |
109952
|
| Summary |
[llvm-cov][MC/DC][Qualification] MCDC coverage does not work for negation
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
escherle-validas
|
# MCDC coverage does not work for negation
## Criticality: HIGH
During qualification of MCDC coverage at Validas we found that
In the following example the term “(!v0) && v1” is not analyzed correctly.
the negation operator takes a boolean input and produces a boolean output.
Therefore it has to be instrumented as well such that the impact from v0 to the result can be analyzed.
This results in a wrongly calculated MCDC coverage measured by LLVMCov.
We also observed that the expected results are wrongly computed in the test vector line, for example v0=T, v1=T
the expected result should be F but is compouted to T
Note1: In plain C there is no native boolean type defined, therefore instrumentation is restricted to && and ||,
but for C++ and Rust the boolean type exists and therefore operators on it should be considered for MCDC coverage.
Note2: In some more complex cases e.g. "if (((!((!FALSE)||TRUE))||((!v0)&&v2)))" a warning is displayed
during instrumentation that the boolean _expression_ is not supported. But this warning is printed not for all negated
terms, where no terms seams to work properly.
The problem occurs within Rust and C++.
Rust example:
Source code and generated reports:
[Test_000011.zip](https://github.com/user-attachments/files/17129320/Test_000011.zip)
C++ example:
Source code and generated reports:
[Test_000011.zip](https://github.com/user-attachments/files/17129337/Test_000011.zip)
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