llvm/test/CodeGen/AMDGPU/spill-empty-live-interval.mir

# RUN: llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -stress-regalloc=1 -start-before=simple-register-coalescing -stop-after=greedy -o - %s | FileCheck %s
# https://bugs.llvm.org/show_bug.cgi?id=33620

---
# This would assert due to the empty live interval created for %9
# on the last S_NOP with an undef subreg use.

# CHECK-LABEL: name: expecting_non_empty_interval

# CHECK: undef %7.sub1:vreg_64 = V_MAC_F32_e32 0, undef %1:vgpr_32, undef %7.sub1, implicit $exec
# CHECK-NEXT: SI_SPILL_V64_SAVE %7, %stack.0, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr5, 0, implicit $exec :: (store 8 into %stack.0, align 4, addrspace 5)
# CHECK-NEXT: undef %5.sub1:vreg_64 = V_MOV_B32_e32 1786773504, implicit $exec
# CHECK-NEXT: dead %3:vgpr_32 = V_MUL_F32_e32 0, %5.sub1, implicit $exec

# CHECK: S_NOP 0, implicit %6.sub1
# CHECK-NEXT: %8:vreg_64 = SI_SPILL_V64_RESTORE %stack.0, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr5, 0, implicit $exec :: (load 8 from %stack.0, align 4, addrspace 5)
# CHECK-NEXT: S_NOP 0, implicit %8.sub1
# CHECK-NEXT: S_NOP 0, implicit undef %9.sub0

name: expecting_non_empty_interval
tracksRegLiveness: true
body:             |
  bb.0:
    successors: %bb.1

    undef %0.sub1:vreg_64 = V_MAC_F32_e32 0, undef %1:vgpr_32, undef %0.sub1, implicit $exec
    undef %2.sub1:vreg_64 = V_MOV_B32_e32 1786773504, implicit $exec
    dead %3:vgpr_32 = V_MUL_F32_e32 0, %2.sub1, implicit $exec

  bb.1:
    S_NOP 0, implicit %2.sub1
    S_NOP 0, implicit %0.sub1
    S_NOP 0, implicit undef %0.sub0

...

# Similar assert which happens when trying to rematerialize.
# https://bugs.llvm.org/show_bug.cgi?id=33884
---
# CHECK-LABEL: name: rematerialize_empty_interval_has_reference

# CHECK-NOT: MOV
# CHECK: undef %1.sub2:vreg_128 = V_MOV_B32_e32 1786773504, implicit $exec

# CHECK: bb.1:
# CHECK-NEXT: S_NOP 0, implicit %1.sub2
# CHECK-NEXT: S_NOP 0, implicit undef %4.sub0
# CHECK-NEXT: undef %2.sub2:vreg_128 = V_MOV_B32_e32 0, implicit $exec
# CHECK-NEXT: S_NOP 0, implicit %2.sub2
name: rematerialize_empty_interval_has_reference
tracksRegLiveness: true
body:             |
  bb.0:
    successors: %bb.1

    undef %0.sub2:vreg_128 = V_MOV_B32_e32 0, implicit $exec
    undef %1.sub2:vreg_128 = V_MOV_B32_e32 1786773504, implicit $exec

  bb.1:
    S_NOP 0, implicit %1.sub2
    S_NOP 0, implicit undef %0.sub0
    S_NOP 0, implicit %0.sub2

...