[llvm] [SelectionDAG] Expand CTTZ_ELTS[_ZERO_POISON] and handle splitting (PR #185605)

Tue Mar 10 03:17:20 PDT 2026

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 170978 tests passed
* 3024 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM
<details>
<summary>LLVM.CodeGen/X86/intrinsic-cttz-elts.ll</summary>

```
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc -mtriple=x86_64-unknown-unknown < /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/X86/intrinsic-cttz-elts.ll | /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/X86/intrinsic-cttz-elts.ll
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc -mtriple=x86_64-unknown-unknown
# .---command stderr------------
# | PromoteIntegerOperand Op #0: t8: i8 = cttz_elts t7
# | 
# | LLVM ERROR: Do not know how to promote this operator's operand!
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
# | Stack dump:
# | 0.	Program arguments: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc -mtriple=x86_64-unknown-unknown
# | 1.	Running pass 'Function Pass Manager' on module '<stdin>'.
# | 2.	Running pass 'X86 DAG->DAG Instruction Selection' on function '@ctz_v8i16'
# |  #0 0x000000000853a7b8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Unix/Signals.inc:880:13
# |  #1 0x0000000008537765 llvm::sys::RunSignalHandlers() /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Signals.cpp:109:18
# |  #2 0x000000000853b5d1 SignalHandler(int, siginfo_t*, void*) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/Unix/Signals.inc:448:38
# |  #3 0x0000794521c2b330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
# |  #4 0x0000794521c84b2c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9eb2c)
# |  #5 0x0000794521c2b27e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
# |  #6 0x0000794521c0e8ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
# |  #7 0x0000000008498195 llvm::report_fatal_error(llvm::Twine const&, bool) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/Support/ErrorHandling.cpp:137:5
# |  #8 0x0000000008497fd6 (/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc+0x8497fd6)
# |  #9 0x0000000008334382 (/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc+0x8334382)
# | #10 0x0000000008318f59 llvm::DAGTypeLegalizer::run() /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp:0:28
# | #11 0x000000000831e147 llvm::SelectionDAG::LegalizeTypes() /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp:1052:34
# | #12 0x0000000008304ab2 llvm::SelectionDAGISel::CodeGenAndEmitDAG() /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1023:23
# | #13 0x00000000083038b3 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1691:8
# | #14 0x00000000083009a0 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:659:22
# | #15 0x00000000082fe070 llvm::SelectionDAGISelLegacy::runOnMachineFunction(llvm::MachineFunction&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:400:20
# | #16 0x00000000071f79b3 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:0:10
# | #17 0x00000000077664f8 llvm::FPPassManager::runOnFunction(llvm::Function&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:0:27
# | #18 0x000000000776dfa2 llvm::FPPassManager::runOnModule(llvm::Module&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1444:13
# | #19 0x0000000007766f6b runOnModule /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1513:27
# | #20 0x0000000007766f6b llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:531:44
# | #21 0x0000000004f5133c compileModule(char**, llvm::SmallVectorImpl<llvm::PassPlugin>&, llvm::LLVMContext&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>&) /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/tools/llc/llc.cpp:871:17
# | #22 0x0000000004f4e603 main /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/tools/llc/llc.cpp:459:13
# | #23 0x0000794521c101ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
# | #24 0x0000794521c1028b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
# | #25 0x0000000004f4a125 _start (/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc+0x4f4a125)
# `-----------------------------
# error: command failed with exit status: -6
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/X86/intrinsic-cttz-elts.ll
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/X86/intrinsic-cttz-elts.ll
# `-----------------------------
# error: command failed with exit status: 2

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/185605