# RUN: llc -o - -mtriple=x86_64-- -run-pass=regallocfast %s | FileCheck %s
# Fast regalloc used to not collect physical register definitions
# before walking and assigning the virtual definition.
# Therefore it was possible for a virtual definition to end up
# using the same register as a later (in terms of operand list) physical
# register.
# Check this does not happen.
#
# PR41790
---
name: instruction_with_1virtreg_1physreg_defs
tracksRegLiveness: true
body: |
  bb.0:
    ; CHECK-NOT: $rax = KILL implicit-def dead $rax
    %0:gr64 = KILL implicit-def dead $rax
    KILL killed %0
    RET 0
...