# RUN: llc %s -mtriple=s390x-linux-gnu -mcpu=z13 \
# RUN:   -start-before=register-coalescer -o - 2>&1 > /dev/null

# Test that the SystemZ shouldCoalesce() implementation does not crash in
# case of an undef use in another MBB. This was discovered in testing with
# -systemz-subreg-liveness.

--- |
  @g_74 = external dso_local unnamed_addr global i32, align 4
  @g_193 = external dso_local unnamed_addr global i32, align 4
  
  define dso_local void @main() local_unnamed_addr {
    %1 = load i32, ptr @g_193
    %2 = or i32 %1, -1395153718
    %3 = sdiv i32 -1395153718, %2
    br i1 undef, label %5, label %4
  
  ; <label>:4:                                      ; preds = %0
    store i32 %3, ptr @g_74
    store i32 -9, ptr @g_74
    ret void
  
  ; <label>:5:                                      ; preds = %0
    unreachable
  }

...
---
name:            main
alignment:       16
tracksRegLiveness: true
registers:       
  - { id: 0, class: grx32bit }
  - { id: 1, class: addr64bit }
  - { id: 2, class: gr32bit }
  - { id: 3, class: gr32bit }
  - { id: 4, class: gr64bit }
  - { id: 5, class: gr128bit }
  - { id: 6, class: gr128bit }
  - { id: 7, class: grx32bit }
  - { id: 8, class: gr32bit }
  - { id: 9, class: gr128bit }
body:             |
  bb.0 (%ir-block.0):
    successors: %bb.2(0x00000001), %bb.1(0x7fffffff)
  
    %1:addr64bit = LARL @g_193
    %2:gr32bit = IIFMux 2899813578
    %3:gr32bit = COPY killed %2
    %3:gr32bit = O %3, killed %1, 0, $noreg, implicit-def dead $cc :: (dereferenceable load (s32) from @g_193)
    %4:gr64bit = LGFI -1395153718
    undef %5.subreg_l64:gr128bit = COPY killed %4
    %6:gr128bit = COPY killed %5
    dead %6:gr128bit = DSGFR %6, killed %3
    %7:grx32bit = LHIMux 0
    CHIMux killed %7, 0, implicit-def $cc
    BRC 14, 6, %bb.2, implicit killed $cc
    J %bb.1
  
  bb.1 (%ir-block.4):
    %8:gr32bit = LHIMux -9
    STRL killed %8, @g_74 :: (store (s32) into @g_74)
    Return
  
  bb.2 (%ir-block.5):
    dead %0:grx32bit = COPY undef %6.subreg_l32

...