[llvm] [AArch64] Lower scalable i1 vector add reduction to cntp (PR #99031)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ml-opt-devrel-x86-64` running on `ml-opt-devrel-x86-64-b1` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/175/builds/2095

Here is the relevant piece of the build log for the reference:
```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/AArch64/sve-i1-add-reduce.ll' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 2: /b/ml-opt-devrel-x86-64-b1/build/bin/llc -mtriple=aarch64-linux-gnu -mattr=+sve < /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/sve-i1-add-reduce.ll | /b/ml-opt-devrel-x86-64-b1/build/bin/FileCheck /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/sve-i1-add-reduce.ll
+ /b/ml-opt-devrel-x86-64-b1/build/bin/llc -mtriple=aarch64-linux-gnu -mattr=+sve
+ /b/ml-opt-devrel-x86-64-b1/build/bin/FileCheck /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/sve-i1-add-reduce.ll
LLVM ERROR: Cannot select: t14: nxv2i64 = AArch64ISD::UADDV_PRED t10, t2
  t10: nxv16i1 = AArch64ISD::PTRUE TargetConstant:i32<31>
    t9: i32 = TargetConstant<31>
  t2: nxv16i1,ch = CopyFromReg t0, Register:nxv16i1 %0
    t1: nxv16i1 = Register %0
In function: uaddv_zexti8_nxv16i1
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /b/ml-opt-devrel-x86-64-b1/build/bin/llc -mtriple=aarch64-linux-gnu -mattr=+sve
1.	Running pass 'Function Pass Manager' on module '<stdin>'.
2.	Running pass 'AArch64 Instruction Selection' on function '@uaddv_zexti8_nxv16i1'
 #0 0x000055f544cf2158 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3de7158)
 #1 0x000055f544cef53c SignalHandler(int) Signals.cpp:0:0
 #2 0x00007efe59e33140 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x13140)
 #3 0x00007efe59934ce1 raise (/lib/x86_64-linux-gnu/libc.so.6+0x38ce1)
 #4 0x00007efe5991e537 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22537)
 #5 0x000055f541921703 (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0xa16703)
 #6 0x000055f544a9aa98 llvm::SelectionDAGISel::CannotYetSelect(llvm::SDNode*) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b8fa98)
 #7 0x000055f544aa2319 llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*, unsigned int) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b97319)
 #8 0x000055f544a9736f llvm::SelectionDAGISel::DoInstructionSelection() (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b8c36f)
 #9 0x000055f544aa7a22 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b9ca22)
#10 0x000055f544aaa8d5 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b9f8d5)
#11 0x000055f544aac0f8 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3ba10f8)
#12 0x000055f544a9dbaf llvm::SelectionDAGISelLegacy::runOnMachineFunction(llvm::MachineFunction&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3b92baf)
#13 0x000055f543c69c97 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#14 0x000055f544274391 llvm::FPPassManager::runOnFunction(llvm::Function&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x3369391)
#15 0x000055f5442745c1 llvm::FPPassManager::runOnModule(llvm::Module&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x33695c1)
#16 0x000055f5442751ab llvm::legacy::PassManagerImpl::run(llvm::Module&) (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0x336a1ab)
#17 0x000055f541a42721 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#18 0x000055f54193964e main (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0xa2e64e)
#19 0x00007efe5991fd0a __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x23d0a)
#20 0x000055f541a38d3a _start (/b/ml-opt-devrel-x86-64-b1/build/bin/llc+0xb2dd3a)
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /b/ml-opt-devrel-x86-64-b1/build/bin/FileCheck /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/sve-i1-add-reduce.ll

--

********************


```

https://github.com/llvm/llvm-project/pull/99031