[all-commits] [llvm/llvm-project] a7130d: [ADT][NFC] Use empty base optimisation in BumpPtrA...

[Nathan James via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: a7130d85e4b9e47b18a89eac3d47fd8c19d449c1
      https://github.com/llvm/llvm-project/commit/a7130d85e4b9e47b18a89eac3d47fd8c19d449c1
  Author: Nathan James <n.james93 at hotmail.co.uk>
  Date:   2021-01-12 (Tue, 12 Jan 2021)

  Changed paths:
    M llvm/include/llvm/Support/Allocator.h

  Log Message:
  -----------
  [ADT][NFC] Use empty base optimisation in BumpPtrAllocatorImpl

Most uses of this class just use the default MallocAllocator.
As this contains no fields, we can use the empty base optimisation for BumpPtrAllocatorImpl and save 8 bytes of padding for most use cases.

This prevents using a class that is marked as `final` as the `AllocatorT` template argument.
In one must use an allocator that has been marked as `final`, the simplest way around this is a proxy class.
The class should have all the methods that `AllocaterBase` expects and should forward the calls to your own allocator instance.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D94439