When using `BranchProbabilityPrinterPass`, if a BB has no name, we get pretty unusable information like `edge -> has probability...` (i.e. we have no idea what the vertices of that edge are).
This patch uses `printAsOperand`, which uses the same naming scheme as `Function::dump`, so for example during debugging sessions, the IR obtained from a function and the names used by `BranchProbabilityPrinterPass` will match.
A shortcoming is that `printAsOperand` will result in the numbering algorithm re-running for every edge and every vertex (when `BranchProbabilityPrinterPass` is run on a function). If, for the given scenario, this is a problem, we can revisit this subsequently.
Another nuance is that the entry basic block will be numbered, which may be slightly confusing when it's anonymous, but it's easily identifiable - the first edge would have it as source (and the number should be easily recognizable)
This patch was split from https://reviews.llvm.org/D102246
[SampleFDO] New hierarchical discriminator for Flow Sensitive SampleFDO
This is mainly for ProfileData part of change. It will load
FS Profile when such profile is detected. For an extbinary format profile,
create_llvm_prof tool will add a flag to profile summary section.
For other format profiles, the users need to use an internal option
(-profile-isfs) to tell the compiler that the profile uses FS discriminators.
This patch also simplified the bit API used by FS discriminators.
Differential Revision: https://reviews.llvm.org/D103041
