- The indexed iFDO profiles contains compressed vtable names for `llvm-profdata show --show-vtables` debugging
usage. An optimized build doesn't need it and doesn't decompress the blob now [1], since optimized binary has the
source code and IR to find vtable symbols.
- The motivation is to avoid increasing profile size when it's not necessary.
- This doesn't change the indexed profile format and thereby doesn't need a version change.
[1] eac925fb81/llvm/include/llvm/ProfileData/InstrProfReader.h (L696-L699)