[all-commits] [llvm/llvm-project] f39f92: [ARM][MVE] tail-predication: overflow checks for e...

[sjoerdmeijer via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: f39f92c1f610fcdfad74730a3e3df881e32a28c2
      https://github.com/llvm/llvm-project/commit/f39f92c1f610fcdfad74730a3e3df881e32a28c2
  Author: Sjoerd Meijer <sjoerd.meijer at arm.com>
  Date:   2020-09-28 (Mon, 28 Sep 2020)

  Changed paths:
    M llvm/lib/Target/ARM/MVETailPredication.cpp
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/tail-pred-basic.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/tail-pred-const.ll
    R llvm/test/CodeGen/Thumb2/LowOverheadLoops/tail-pred-forced.ll

  Log Message:
  -----------
  [ARM][MVE] tail-predication: overflow checks for elementcount, cont'd

This is a reimplementation of the overflow checks for the elementcount,
i.e. the 2nd argument of intrinsic get.active.lane.mask. The element
count is lowered in each iteration of the tail-predicated loop, and
we must prove that this expression doesn't overflow.

Many thanks to Eli Friedman and Sam Parker for all their help with
this work.

Differential Revision: https://reviews.llvm.org/D88086