Wrong MC/DC code generation with ternary operator

[chapuni]

(https://godbolt.org/z/qYKKnvbva)

bool foo(bool a, bool b, bool c, bool d, bool e) {
    return (a || b ? c && d : e);
}

This is not rejected (as unsupported) but wrong code is generated.
CoverageGen emits a couple of decisions but CodeGen emits weird code.
Finally, llvm-cov crashes with unexpected test vector.

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: NAKAMURA Takumi (chapuni)

(https://godbolt.org/z/qYKKnvbva) ``` bool foo(bool a, bool b, bool c, bool d, bool e) { return (a || b ? c && d : e); } ```

This is not rejected (as unsupported) but wrong code is generated.
CoverageGen emits a couple of decisions but CodeGen emits weird code.
Finally, llvm-cov crashes with unexpected test vector.

[chapuni]

Seems this is generic to split decisions, like func(a && b, c && d).
https://godbolt.org/z/5h1dqc4be

Can I retitle?

[evodius96]

The temporary bitmap value for the ternary operator's condition was being saved after its LHS and RHS was evaluated, which means that if the LHS or RHS has a boolean expression, the bitmap value will become corrupted, and the bitmaps for all of the boolean expressions will be wrong. The fix is to ensure that the temporary bitmap value for the ternary operator's condition is saved prior to visiting the LHS and RHS. It's a straightforward fix, but I'll put up a PR soon.

[chapuni]

Thanks!