third_party/llvm-7.0/llvm/test/CodeGen/AArch64/machine-sink-zr.mir

# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-sink -o - %s | FileCheck %s
--- |
  define void @sinkwzr() { ret void }
...
---
name:            sinkwzr
tracksRegLiveness: true
registers:
  - { id: 0, class: gpr32 }
  - { id: 1, class: gpr32 }
  - { id: 2, class: gpr32sp }
  - { id: 3, class: gpr32 }
  - { id: 4, class: gpr32 }
body:             |
  ; Check that WZR copy is sunk into the loop preheader.
  ; CHECK-LABEL: name: sinkwzr
  ; CHECK-LABEL: bb.0:
  ; CHECK-NOT: COPY $wzr
  bb.0:
    liveins: $w0

    %0 = COPY $w0
    %1 = COPY $wzr
    CBZW %0, %bb.3

  ; CHECK-LABEL: bb.1:
  ; CHECK: COPY $wzr

  bb.1:
    B %bb.2

  bb.2:
    %2 = PHI %0, %bb.1, %4, %bb.2
    $w0 = COPY %1
    %3 = SUBSWri %2, 1, 0, implicit-def dead $nzcv
    %4 = COPY %3
    CBZW %3, %bb.3
    B %bb.2

  bb.3:
    RET_ReallyLR

...