third_party/llvm-7.0/llvm/test/CodeGen/Hexagon/hwloop-redef-imm.mir

# RUN: llc -march=hexagon -run-pass hwloops %s -o - | FileCheck %s

# Normally, if the registers holding the induction variable's bounds
# are redefined inside of the loop's body, the loop cannot be converted
# to a hardware loop. However, if the redefining instruction is actually
# loading an immediate value into the register, this conversion is both
# possible and legal (since the immediate itself will be used in the
# loop setup in the preheader).

# CHECK:  [[R0:%[0-9]+]]:intregs = A2_tfrsi 1920
# CHECK:  J2_loop0r %bb.1, [[R0]]
#
# CHECK: bb.1.b1 (address-taken):
# CHECK:   ENDLOOP0 %bb.1


--- |
  define void @fred() {
  b0:
    br label %b1
  b1:
    br label %b2
  b2:
    ret void
  }
...

---
name: fred
tracksRegLiveness: true
registers:
  - { id: 0, class: intregs }
  - { id: 1, class: intregs }
  - { id: 2, class: intregs }
  - { id: 3, class: intregs }
  - { id: 4, class: intregs }
  - { id: 5, class: intregs }
  - { id: 6, class: intregs }
  - { id: 7, class: intregs }
  - { id: 8, class: predregs }
body: |
  bb.0.b0:
    liveins: $r0
    successors: %bb.1
    %0 = A2_tfrsi 0
    %1 = A2_tfrsi 0
    %2 = COPY $r0

  bb.1.b1:
    successors: %bb.1, %bb.2
    %3 = PHI %0, %bb.0, %6, %bb.1
    %4 = PHI %1, %bb.0, %5, %bb.1
    S4_storerh_rr %2, %4, 0, %3
    %5 = A2_addi %4, 2
    %6 = A2_addi %3, 1
    ; This definition of %7 should not prevent conversion to hardware loop.
    %7 = A2_tfrsi 3840
    %8 = C2_cmpeq %5, %7
    J2_jumpf %8, %bb.1, implicit-def $pc
    J2_jump %bb.2, implicit-def $pc

  bb.2.b2:
...