src/llvm-project/llvm/test/CodeGen/ARM/ifcvt_canFallThroughTo.mir

# RUN: llc -mtriple=arm-apple-ios -o - %s -run-pass if-converter | FileCheck %s
---
name:            f1
body:             |
  bb.0:
    successors: %bb.1

    B %bb.1

  bb.1:
    successors: %bb.2, %bb.4

    Bcc %bb.4, 1, $cpsr

  bb.2:
    successors: %bb.3, %bb.5

    Bcc %bb.5, 1, $cpsr

  bb.3:
    successors: %bb.5

    B %bb.5

  bb.4:
    successors:

  bb.5:
    successors: %bb.1, %bb.6

    Bcc %bb.1, 1, $cpsr

  bb.6:
    BX_RET 14, _

...

# IfConversion.cpp/canFallThroughTo thought there was a fallthrough from
# bb.4 to bb5 even if the successor list was empty.
# bb.4 is empty, so it surely looks like it can fallthrough, but this is what
# happens for a bb just containing an "unreachable".

#CHECK: body:             |
#CHECK:   bb.0:
#CHECK:     successors: %bb.1

#CHECK:   bb.1:
#CHECK:     successors: %bb.3({{.*}}), %bb.2

# The original brr_cond from bb.1, jumping to the empty bb
#CHECK:     Bcc %bb.2
#CHECK:     B %bb.3

# Empty bb.2, originally containing "unreachable" and thus has no successors
# and we cannot guess them: we should print an empty list of successors.
#CHECK:   bb.2:
#CHECK: successors:{{ *$}}

#CHECK:   bb.3:
#CHECK:     successors: %bb.1

# Conditional BX_RET and then loop back to bb.1
#CHECK:     BX_RET 0
#CHECK:     B %bb.1