Improve DeltaTree update routine

[SchrodingerZhu]

Enhancement

On DeltaTree update routine (afterNodeUpdated), the call to getDelta() can be effectively translated by the compiler to SIMD memory scanning.

Since compiler has already decides that afterNodeUpdated is too large to be inlined, we can actually dispatch this function to multiple targets. Indeed, it enjoys different codegen for avx targets:

Experiments have shown that, it can provide up to 12% speed up at IDC environment:

2022-06-23T08:53:15+08:00
Running dbms/src/Storages/DeltaMerge/Benchmark/bench_deltatree
Run on (40 X 2394.97 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB (x20)
  L1 Instruction 32 KiB (x20)
  L2 Unified 256 KiB (x20)
  L3 Unified 25600 KiB (x2)
Load Average: 8.91, 23.44, 19.41
------------------------------------------------------------------------------------------------
Benchmark                                                      Time             CPU   Iterations
------------------------------------------------------------------------------------------------
BM_deltatree_dispatch<true>/iterations:50/threads:40     1764554 ns     59946595 ns         2000
BM_deltatree_dispatch<false>/iterations:50/threads:40    1553962 ns     55583999 ns         2000

[SchrodingerZhu]

Test cases:

template <bool use_generic>
static void BM_deltatree_dispatch(benchmark::State & state)
{
    if (use_generic)
    {
        DB::DM::Impl::DELTA_TREE_VARIANT = DB::DM::Impl::DeltaTreeVariant::Generic;
    } else {
        DB::DM::Impl::DELTA_TREE_VARIANT = DB::DM::Impl::resolveDeltaTreeVariant();
    }

    SystemTree tree;
    for (auto _ : state)
    {
        for (int i = 0; i < 32768; ++i)
        {
            tree.addInsert(i, i);
        }
        for (int i = 0; i < 32768; ++i)
        {
            tree.addDelete(i);
        }

    }
}

BENCHMARK_TEMPLATE(BM_deltatree_dispatch, true)->Iterations(50);
BENCHMARK_TEMPLATE(BM_deltatree_dispatch, false)->Iterations(50); 

[flowbehappy]

Looks like it only works for x86. Is there anyway to port to arm?