llvm/llvm/test/CodeGen/X86/implicit-null-chk-reg-rewrite.mir

# RUN: llc -mtriple=x86_64 -run-pass=implicit-null-checks %s -o - | FileCheck %s
--- |

  define i32 @reg-rewrite(ptr %x) {
  entry:
    br i1 undef, label %is_null, label %not_null, !make.implicit !0

  is_null:
    ret i32 42

  not_null:
    ret i32 100
  }

  !0 = !{}

...
---
# Check that the TEST instruction is replaced with 
# FAULTING_OP only if there are no instructions
# between the TEST and conditional jump
# that clobber the register used in TEST.
name:            reg-rewrite

alignment:       16
tracksRegLiveness: true
liveins:
  - { reg: '$rdi' }

body:             |
  bb.0.entry:
    liveins: $rdi

    TEST64rr $rdi, $rdi, implicit-def $eflags
    ; CHECK-LABEL: bb.0.entry
    ; CHECK-NOT: FAULTING_OP
    renamable $rdi = MOV64ri 5000
    JCC_1 %bb.2, 4, implicit $eflags

  bb.1.not_null:
    liveins: $rdi, $rsi
    
    $rax = MOV64rm renamable $rdi, 1, $noreg, 4, $noreg
    RET64 $eax

  bb.2.is_null:
    $eax = MOV32ri 200
    RET64 $eax
...