[llvm] [BOLT] Adding a unittest that covers Arm SPE PBT aggregation (PR #160095)

[Paschalis Mpeis via llvm-commits]

=?utf-8?b?w4Fkw6Ft?= Kallai <kadam at inf.u-szeged.hu>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/160095 at github.com>


paschalis-mpeis wrote:

Thanks for confirming and the added info, @mate-stodulka.

So we can reword the test and clarify that:
1. The PBT entry is always taken, acting as a branch-stack like structure of depth 1.
2. The current source branch may be either fall-through or taken.
3. The recorded dest branch is always what was architecturally executed.

We have opportunities to infer FTs from (1) up to (2), regardless of what (2) is, but none between (2) and (3).

https://github.com/llvm/llvm-project/pull/160095