[all-commits] [llvm/llvm-project] 01022a: [ARM][MVE] LowOverheadLoops: DCE on the iteration ...

[sjoerdmeijer via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 01022af5d5a109c903e843f0e33378b5bc805ed1
      https://github.com/llvm/llvm-project/commit/01022af5d5a109c903e843f0e33378b5bc805ed1
  Author: Sjoerd Meijer <sjoerd.meijer at arm.com>
  Date:   2020-02-05 (Wed, 05 Feb 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/dont-ignore-vctp.mir
    A llvm/test/CodeGen/Thumb2/LowOverheadLoops/it-block-chain.mir
    A llvm/test/CodeGen/Thumb2/LowOverheadLoops/it-block-itercount.mir
    A llvm/test/CodeGen/Thumb2/LowOverheadLoops/it-block-random.mir

  Log Message:
  -----------
  [ARM][MVE] LowOverheadLoops: DCE on the iteration count setup expression

Once we have created a tail-predicated hardware-loop, and thus know the number
of elements that are processed, we want to clean-up the iteration count
expression of that loop. In D73682, we bailed the analysis on conditionally
executed instructions. This adds support for IT-blocks, so that we can handle
these cases again. The restriction is that we only support IT blocks containing
1 statement, but that seems to cover most cases and forms of the iteration
count expression.

Differential Revision: https://reviews.llvm.org/D73947