[all-commits] [llvm/llvm-project] e7dc08: [ARM] Don't handle low overhead branches in Analyz...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e7dc083a410f187e143138b4956993370626268b
      https://github.com/llvm/llvm-project/commit/e7dc083a410f187e143138b4956993370626268b
  Author: David Green <david.green at arm.com>
  Date:   2021-01-18 (Mon, 18 Jan 2021)

  Changed paths:
    M llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/fast-fp-loops.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/mve-float-loops.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/sibling-loops.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/varying-outer-2d-reduction.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/vcmp-vpst-combination.ll
    M llvm/test/CodeGen/Thumb2/LowOverheadLoops/while-loops.ll
    M llvm/test/CodeGen/Thumb2/aligned-nonfallthrough.ll
    A llvm/test/CodeGen/Thumb2/mve-blockplacement.ll
    M llvm/test/CodeGen/Thumb2/mve-float16regloops.ll
    M llvm/test/CodeGen/Thumb2/mve-float32regloops.ll
    M llvm/test/CodeGen/Thumb2/mve-gather-increment.ll
    M llvm/test/CodeGen/Thumb2/mve-gather-scatter-optimisation.ll
    M llvm/test/CodeGen/Thumb2/mve-gather-tailpred.ll
    M llvm/test/CodeGen/Thumb2/mve-satmul-loops.ll
    M llvm/test/CodeGen/Thumb2/mve-scatter-increment.ll
    M llvm/test/CodeGen/Thumb2/mve-vecreduce-loops.ll
    M llvm/test/CodeGen/Thumb2/mve-vldshuffle.ll

  Log Message:
  -----------
  [ARM] Don't handle low overhead branches in AnalyzeBranch

It turns our that the BranchFolder and IfCvt does not like unanalyzable
branches that fall-through. This means that removing the unconditional
branches from the end of tail predicated instruction can run into
asserts and verifier issues.

This effectively reverts 372eb2bbb6fb903ce76266e659dfefbaee67722b, but
adds handling to t2DoLoopEndDec which are not branches, so can be safely
skipped.