test/CodeGen/Hexagon/branchfolder-insert-impdef.mir

# RUN: llc -march=hexagon -run-pass branch-folder %s -o - -verify-machineinstrs | FileCheck %s

# Branch folding will perform tail merging of bb.1 and bb.2, and bb.2 will
# become the common tail. The use of R0 in bb.2 is <undef> while the
# corresponding use in bb.1 is not. The common tail will have the <undef>
# flag removed, which will cause R0 to become a live-in to bb.2. The problem
# is that R0 is not live-out from all predecessors of bb.2, namely is not
# live-out from bb.0. To remedy that, the branch folder should add an
# IMPLICIT_DEF to that block.

# CHECK-LABEL: name: func0
# CHECK-LABEL: bb.0:
# CHECK: %r0 = IMPLICIT_DEF
# CHECK-LABEL: bb.1:
# CHECK-LABEL: bb.2:
# CHECK: liveins: %r0
# CHECK: PS_storerhabs 0, %r0
# CHECK: PS_jmpret

---
name: func0
tracksRegLiveness: true

body: |
  bb.0:
    liveins: %r31
    successors: %bb.1, %bb.2
      J2_jumpt undef %p0, %bb.2, implicit-def %pc
      J2_jump %bb.1, implicit-def %pc

  bb.1:
    liveins: %r31
    successors: %bb.3
      %r0 = L2_loadruh_io undef %r1, 0
      PS_storerhabs 0, killed %r0
      J2_jump %bb.3, implicit-def %pc

  bb.2:
    liveins: %r31
    successors: %bb.3
      PS_storerhabs 0, undef %r0
      J2_jump %bb.3, implicit-def %pc

  bb.3:
    liveins: %r31
      PS_jmpret killed %r31, implicit-def %pc
...
---
# CHECK-LABEL: name: func1
# CHECK-LABEL: bb.1:
# CHECK: %r0 = IMPLICIT_DEF
# CHECK-LABEL: bb.2:
# CHECK-LABEL: bb.3:
# CHECK: liveins: %r0
# CHECK: PS_storerhabs 0, killed %r0
# CHECK: PS_jmpret

name: func1
tracksRegLiveness: true

body: |
  bb.0:
    liveins: %r31
    successors: %bb.1, %bb.2
      J2_jumpt undef %p0, %bb.2, implicit-def %pc
      J2_jump %bb.1, implicit-def %pc

  bb.1:
    liveins: %r31
    successors: %bb.3
      %r1 = A2_tfrsi 1
      PS_storerhabs 0, undef %r0
      %r0 = A2_tfrsi 1
      J2_jump %bb.3, implicit-def %pc

  bb.2:
    liveins: %r31
    successors: %bb.3
      %r0 = L2_loadruh_io undef %r1, 0
      PS_storerhabs 0, killed %r0
      %r0 = A2_tfrsi 1
      J2_jump %bb.3, implicit-def %pc

  bb.3:
    liveins: %r31
      PS_jmpret killed %r31, implicit undef %r0, implicit-def %pc
...