[llvm] [BOLT][AArch64] Relax calls and branches with fragment clusters (PR #215825)

[Alexandros Lamprineas via llvm-commits]

labrinea wrote:

> @labrinea
> 
> I tested this new stack but it broke for me and generated out-of-range calls, I bisected the problem to commit "refactor branch collection and get rid of relax-plt". It dropped the containment guard from the adjacent-cluster long-thunk reuse:
> 
> ```
>          if (ReuseCluster) {
>            auto It = ReuseCluster->CallThunks.find(TargetSymbol);
>   -        if (It != ReuseCluster->CallThunks.end() &&
>   -            llvm::is_contained(*ReuseThunkList, It->second)) {
>   +        if (It != ReuseCluster->CallThunks.end()) {
>              BinaryFunction *Thunk = It->second;
> ```
> 
> That guard was the "only reuse if the neighbor actually hosts this thunk" check. Without it, reuse becomes transitive.

Thanks @rafaelauler, this should be fixed now.

https://github.com/llvm/llvm-project/pull/215825