test/CodeGen/AMDGPU/regalloc-csr-alias.mir

# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -mtriple=amdgpu9.00-amd-amdhsa -passes='greedy<sgpr>,virt-reg-rewriter' %s -o - | FileCheck %s

--- |
  define void @tuple_unused_csr() { ret void }
  define void @tuple_unused_lane() { ret void }
  declare void @callee()
...
---
# SGPR48 is already used, but SGPR49 is not. The tuple must still incur a
# first-use CSR cost, making rematerialization after the call cheaper.
name: tuple_unused_csr
tracksRegLiveness: true
registers:
  - { id: 0, class: sgpr_32, preferred-register: '$sgpr48' }
  - { id: 1, class: sgpr_64, preferred-register: '$sgpr48_sgpr49' }
body: |
  bb.0:
    liveins: $sgpr48
    ; CHECK-LABEL: name: tuple_unused_csr
    ; CHECK: liveins: $sgpr48
    ; CHECK-NEXT: {{  $}}
    ; CHECK-NEXT: S_NOP 0, implicit renamable $sgpr48
    ; CHECK-NEXT: S_NOP 0, implicit renamable $sgpr48
    ; CHECK-NEXT: S_NOP 0, implicit killed renamable $sgpr48
    ; CHECK-NEXT: dead $sgpr30_sgpr31 = SI_CALL undef $sgpr4_sgpr5, @callee, csr_amdgpu
    ; CHECK-NEXT: renamable $sgpr0_sgpr1 = S_MOV_B64 1
    ; CHECK-NEXT: S_NOP 0, implicit killed renamable $sgpr0_sgpr1
    ; CHECK-NEXT: S_ENDPGM 0
    %0:sgpr_32 = COPY $sgpr48
    S_NOP 0, implicit %0
    S_NOP 0, implicit %0
    S_NOP 0, implicit %0
    %1:sgpr_64 = S_MOV_B64 1
    dead $sgpr30_sgpr31 = SI_CALL undef $sgpr4_sgpr5, @callee, csr_amdgpu
    S_NOP 0, implicit %1
    S_ENDPGM 0
...
---
# Only sub0 is live, so assigning the tuple to SGPR48_SGPR49 does not use
# SGPR49. Reusing SGPR48 incurs no first-use cost and needs no rematerialization.
name: tuple_unused_lane
tracksRegLiveness: true
registers:
  - { id: 0, class: sgpr_32, preferred-register: '$sgpr48' }
  - { id: 1, class: sgpr_64, preferred-register: '$sgpr48_sgpr49' }
body: |
  bb.0:
    liveins: $sgpr48
    ; CHECK-LABEL: name: tuple_unused_lane
    ; CHECK: liveins: $sgpr48
    ; CHECK-NEXT: {{  $}}
    ; CHECK-NEXT: S_NOP 0, implicit renamable $sgpr48
    ; CHECK-NEXT: S_NOP 0, implicit renamable $sgpr48
    ; CHECK-NEXT: S_NOP 0, implicit killed renamable $sgpr48
    ; CHECK-NEXT: renamable $sgpr48 = S_MOV_B32 1
    ; CHECK-NEXT: dead $sgpr30_sgpr31 = SI_CALL undef $sgpr4_sgpr5, @callee, csr_amdgpu
    ; CHECK-NEXT: S_NOP 0, implicit killed renamable $sgpr48
    ; CHECK-NEXT: S_ENDPGM 0
    %0:sgpr_32 = COPY $sgpr48
    S_NOP 0, implicit %0
    S_NOP 0, implicit %0
    S_NOP 0, implicit %0
    undef %1.sub0:sgpr_64 = S_MOV_B32 1
    dead $sgpr30_sgpr31 = SI_CALL undef $sgpr4_sgpr5, @callee, csr_amdgpu
    S_NOP 0, implicit %1.sub0
    S_ENDPGM 0
...