By storing possible test vectors instead of combinations of conditions,
the restriction is dramatically relaxed.
This introduces two options to `cc1`:
* `-fmcdc-max-conditions=32767`
* `-fmcdc-max-test-vectors=2147483646`
This change makes coverage mapping, profraw, and profdata incompatible
with Clang-18.
- Bitmap semantics changed. It is incompatible with previous format.
- `BitmapIdx` in `Decision` points to the end of the bitmap.
- Bitmap is packed per function.
- `llvm-cov` can understand `profdata` generated by `llvm-profdata-18`.
RFC:
https://discourse.llvm.org/t/rfc-coverage-new-algorithm-and-file-format-for-mc-dc/76798
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Change(s) since llvmorg-19-init-14288-g7ead2d8c7e91
- Update compiler-rt/test/profile/ContinuousSyncMode/image-with-mcdc.c
71f8b441ed