[NFC][CodeGen][AArch64] Add tests for unconditional branch duplication

c9f3288 introduced unconditional branch deduplication for basic block
sections and machine function splitting, but it didn't add tests for
AArch64 since prior behavior crashed the test.

This change adds tests for AArch64 and has no functional change.

Author: dhoekwater

llvm/test/CodeGen/Generic/machine-function-splitter.ll

@@ -12,6 +12,7 @@
 ; RUN: llc < %s -mtriple=aarch64-unknown-linux-gnu -aarch64-min-jump-table-entries=4 -enable-split-machine-functions -mfs-psi-cutoff=0 -mfs-count-threshold=2000 | FileCheck %s --dump-input=always -check-prefixes=MFS-OPTS1,MFS-OPTS1-AARCH64
 ; RUN: llc < %s -mtriple=aarch64-unknown-linux-gnu -aarch64-min-jump-table-entries=4 -enable-split-machine-functions -mfs-psi-cutoff=950000 | FileCheck %s -check-prefixes=MFS-OPTS2,MFS-OPTS2-AARCH64
 ; RUN: llc < %s -mtriple=aarch64-unknown-linux-gnu -aarch64-min-jump-table-entries=4 -enable-split-machine-functions -mfs-split-ehcode | FileCheck %s -check-prefixes=MFS-EH-SPLIT,MFS-EH-SPLIT-AARCH64
+; RUN: llc < %s -mtriple=aarch64 -split-machine-functions -O0 -mfs-psi-cutoff=0 -mfs-count-threshold=10000 | FileCheck %s -check-prefixes=MFS-O0,MFS-O0-AARCH64
 ; RUN: llc < %s -mtriple=aarch64 -enable-split-machine-functions -aarch64-redzone | FileCheck %s -check-prefixes=MFS-REDZONE-AARCH64
 
 ; COM: Machine function splitting with AFDO profiles
@@ -470,9 +471,8 @@ define void @foo16(i1 zeroext %0) nounwind !prof !14 !section_prefix !15 {
 ; MFS-O0-LABEL:               foo16
 ; MFS-O0-X86:                 jmp
 ; MFS-O0-X86-NOT:             jmp
-; MFS-O0-AARCH64:                 br
-; MFS-O0-AARCH64:                 br
-; MFS-O0-AARCH64-NOT:             br
+; MFS-O0-AARCH64:                 b       foo16.cold
+; MFS-O0-AARCH64-NOT:             b       foo16.cold
 ; MFS-O0:                     .section        .text.split.foo16
 ; MFS-O0-NEXT:                foo16.cold
   %2 = call i32 @baz()