[all-commits] [llvm/llvm-project] e47449: [ARM] Treat memcpy/memset/memmove as call instruct...

[David Green via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: e47449940227a9feab51c997d87df3aa06878c91
      https://github.com/llvm/llvm-project/commit/e47449940227a9feab51c997d87df3aa06878c91
  Author: David Green <david.green at arm.com>
  Date:   2020-11-03 (Tue, 03 Nov 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
    M llvm/lib/Target/ARM/ARMTargetTransformInfo.h
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/memcall.ll

  Log Message:
  -----------
  [ARM] Treat memcpy/memset/memmove as call instructions for low overhead loops

If an instruction will be lowered to a call there is no advantage of
using a low overhead loop as the LR register will need to be spilled and
reloaded around the call, and the low overhead will end up being
reverted. This teaches our hardware loop lowering that these memory
intrinsics will be calls under certain situations.

Differential Revision: https://reviews.llvm.org/D90439