[C++] BasicDecimal128 is a small object it doesn't always make sense to pass by const ref

[asfimport]

For the builder use case we saw 10% improvement in performance by not using const ref.
Add benchmarks and look at where it makes sense to avoid passing by ref.

Reporter: Micah Kornfield / @emkornfield
Assignee: Micah Kornfield / @emkornfield

Subtasks:

• [C++] Add benchmark for Decimal128 operations

PRs and other links:

• GitHub Pull Request #4739

_{Note: This issue was originally created as ARROW-5777. Please see the migration documentation for further details.}

[asfimport]

Micah Kornfield / @emkornfield:
currently benchmarking shows now appreciable difference to slight performance loss for making this change. According the literature it should improve things but we don't observe it so we will just check in the benchmarks for now and this can be revisited later.

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 4739
#4739