llvm-project/llvm/test/CodeGen/X86/GlobalISel/select-undef.mir

# RUN: llc -mtriple=x86_64-linux-gnu -global-isel -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s --check-prefix=ALL
--- |

  define i8 @test() {
    ret i8 undef
  }

  define i8 @test2(i8 %a) {
    %r = add i8 %a, undef
    ret i8 %r
  }

...
---
name:            test
# ALL-LABEL: name:  test
alignment:       4
legalized:       true
regBankSelected: true
# ALL:      registers:
# ALL-NEXT:   - { id: 0, class: gr8, preferred-register: '' }
registers:
  - { id: 0, class: gpr, preferred-register: '' }
liveins:
fixedStack:
stack:
constants:
# ALL:          %0 = IMPLICIT_DEF
# ALL-NEXT:     %al = COPY %0
# ALL-NEXT:     RET 0, implicit %al
body:             |
  bb.1 (%ir-block.0):
    %0(s8) = G_IMPLICIT_DEF
    %al = COPY %0(s8)
    RET 0, implicit %al

...
---
name:            test2
# ALL-LABEL: name:  test2
alignment:       4
legalized:       true
regBankSelected: true
# ALL:      registers:
# ALL-NEXT:   - { id: 0, class: gr8, preferred-register: '' }
# ALL-NEXT:   - { id: 1, class: gr8, preferred-register: '' }
# ALL-NEXT:   - { id: 2, class: gr8, preferred-register: '' }
registers:
  - { id: 0, class: gpr, preferred-register: '' }
  - { id: 1, class: gpr, preferred-register: '' }
  - { id: 2, class: gpr, preferred-register: '' }
liveins:
fixedStack:
stack:
constants:
# ALL:          %0 = COPY %dil
# ALL-NEXT:     %1 = IMPLICIT_DEF
# ALL-NEXT:     %2 = ADD8rr %0, %1, implicit-def %eflags
# ALL-NEXT:     %al = COPY %2
# ALL-NEXT:     RET 0, implicit %al
body:             |
  bb.1 (%ir-block.0):
    liveins: %edi

    %0(s8) = COPY %dil
    %1(s8) = G_IMPLICIT_DEF
    %2(s8) = G_ADD %0, %1
    %al = COPY %2(s8)
    RET 0, implicit %al

...