A function is already emitted in *GenInstrInfo.inc that takes Opcode
number and a set of supported Features and reports fatal error if some
of the required features are missing.
The information about features required by the particular opcode can be
reused by llvm-exegesis, so move its computation info a separate
computeRequiredFeatures() function. Then verifyInstructionPredicates()
can just compare the sets of available and required features computed by
the other functions.
This commit moves the definition of FeatureBitsets as well as CEFBS_*
enumerator values (that are indices into FeatureBitsets array) inside
the computeRequiredFeatures() function because these are implementation
details of that function. The inclusion of potentially huge
computeRequiredFeatures() function is now controlled by a dedicated
macro that is set for simplicity by TableGen-erated code itself if
defined(ENABLE_INSTR_PREDICATE_VERIFIER) && !defined(NDEBUG).
Huawei RRI, OS Lab