third_party/llvm-7.0/llvm/test/CodeGen/AArch64/ldst-opt-zr-clobber.mir

# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass aarch64-ldst-opt  -verify-machineinstrs  -o - %s | FileCheck %s

--- |
  define i1 @no-clobber-zr(i64* %p, i64 %x) { ret i1 0 }
...
---
# Check that write of xzr doesn't inhibit pairing of xzr stores since
# it isn't actually clobbered.  Written as a MIR test to avoid
# schedulers reordering instructions such that SUBS doesn't appear
# between stores.
# CHECK-LABEL: name: no-clobber-zr
# CHECK: STPXi $xzr, $xzr, $x0, 0
name: no-clobber-zr
body: |
  bb.0:
    liveins: $x0,  $x1
    STRXui $xzr, $x0, 0 :: (store 8 into %ir.p)
    dead $xzr = SUBSXri killed $x1, 0, 0, implicit-def $nzcv
    $w8 = CSINCWr $wzr, $wzr, 1, implicit killed $nzcv
    STRXui $xzr, killed $x0, 1 :: (store 8 into %ir.p)
    $w0 = ORRWrs $wzr, killed $w8, 0
    RET $lr, implicit $w0
...