[PATCH] D136014: [AArch64] Improve codegen for shifted mask op

Thu Nov 3 09:21:34 PDT 2022

nathanchance added subscribers: nickdesaulniers, nathanchance.
nathanchance added a comment.

I bisect a crash while compiling the Linux kernel to this change. A simplified C reproducer (sorry, I do not have time at the moment for `llvm-reduce`):

  union drbd_state {
    struct {
      unsigned : 5;
      unsigned : 4;
      unsigned susp_nod : 1;
      unsigned susp_fen : 1;
    };
    int i;
  } drbd_req_state_ns;
  enum chg_state_flags {
    CS_DC_PDSK
  } _drbd_set_state(union drbd_state, enum chg_state_flags, int *);
  struct {
    unsigned susp_nod : 1;
    unsigned susp_fen : 1;
  } resource;
  int apply_mask_val_mask_1, drbd_req_state_done;
  enum chg_state_flags drbd_req_state_f;
  void drbd_req_state() {
    union drbd_state rv;
    rv.susp_nod = resource.susp_nod;
    rv.susp_fen = resource.susp_fen;
    drbd_req_state_ns.i = rv.i & apply_mask_val_mask_1;
    _drbd_set_state(drbd_req_state_ns, drbd_req_state_f, &drbd_req_state_done);
  }

  $ clang --target=aarch64-linux-gnu -O2 -c -o /dev/null drbd_state.i
  clang: /home/nathan/cbl/src/llvm-project/llvm/include/llvm/ADT/APInt.h:1027: bool llvm::APInt::operator==(const llvm::APInt &) const: Assertion `BitWidth == RHS.BitWidth && "Comparison requires equal bit widths"' failed.
  PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
  Stack dump:
  0.      Program arguments: clang --target=aarch64-linux-gnu -O2 -c -o /dev/null drbd_state.i
  1.      <eof> parser at end of file
  2.      Code generation
  3.      Running pass 'Function Pass Manager' on module 'drbd_state.i'.
  4.      Running pass 'AArch64 Instruction Selection' on function '@drbd_req_state'
   #0 0x000056317d224071 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x408b071)
   #1 0x000056317d221f9e llvm::sys::RunSignalHandlers() (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4088f9e)
   #2 0x000056317d22344b llvm::sys::CleanupOnSignal(unsigned long) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x408a44b)
   #3 0x000056317d1a6e7e (anonymous namespace)::CrashRecoveryContextImpl::HandleCrash(int, unsigned long) CrashRecoveryContext.cpp:0:0
   #4 0x000056317d1a70d7 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
   #5 0x00007f04d3bc6a00 (/usr/lib/libc.so.6+0x38a00)
   #6 0x00007f04d3c1664c (/usr/lib/libc.so.6+0x8864c)
   #7 0x00007f04d3bc6958 raise (/usr/lib/libc.so.6+0x38958)
   #8 0x00007f04d3bb053d abort (/usr/lib/libc.so.6+0x2253d)
   #9 0x00007f04d3bb045c (/usr/lib/libc.so.6+0x2245c)
  #10 0x00007f04d3bbf486 (/usr/lib/libc.so.6+0x31486)
  #11 0x000056317ba4ad5e (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x28b1d5e)
  #12 0x000056317e3b3d9a (anonymous namespace)::DAGCombiner::visitShiftByConstant(llvm::SDNode*) DAGCombiner.cpp:0:0
  #13 0x000056317e35f1f0 (anonymous namespace)::DAGCombiner::visitSHL(llvm::SDNode*) DAGCombiner.cpp:0:0
  #14 0x000056317e34b6c8 (anonymous namespace)::DAGCombiner::combine(llvm::SDNode*) DAGCombiner.cpp:0:0
  #15 0x000056317e346ad4 llvm::SelectionDAG::Combine(llvm::CombineLevel, llvm::AAResults*, llvm::CodeGenOpt::Level) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x51adad4)
  #16 0x000056317e4d1452 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x5338452)
  #17 0x000056317e4d0082 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x5337082)
  #18 0x000056317e4cc6b5 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x53336b5)
  #19 0x000056317c60740b llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x346e40b)
  #20 0x000056317caec265 llvm::FPPassManager::runOnFunction(llvm::Function&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x3953265)
  #21 0x000056317caf3e91 llvm::FPPassManager::runOnModule(llvm::Module&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x395ae91)
  #22 0x000056317caecbd8 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x3953bd8)
  #23 0x000056317db0846f clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, std::unique_ptr<llv
  m::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x496f46f)
  #24 0x000056317e02d1ad clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) CodeGenAction.cpp:0:0
  #25 0x000056317e8dd789 clang::ParseAST(clang::Sema&, bool, bool) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x5744789)
  #26 0x000056317e02b1d4 clang::CodeGenAction::ExecuteAction() (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4e921d4)
  #27 0x000056317df56a7e clang::FrontendAction::Execute() (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4dbda7e)
  #28 0x000056317debbbbf clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4d22bbf)
  #29 0x000056317e025d63 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4e8cd63)
  #30 0x000056317b9cad97 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x2831d97)
  #31 0x000056317b9c772b ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
  #32 0x000056317dd20ae2 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::$_1>(long) Job.cpp:0:
  0
  #33 0x000056317d1a6cf9 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x400dcf9)
  #34 0x000056317dd203de clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4b8
  73de)
  #35 0x000056317dce1054 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4b48054)
  #36 0x000056317dce131e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4b4831e)
  #37 0x000056317dcff73f clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x4b6673f)
  #38 0x000056317b9c6c64 clang_main(int, char**) (/home/nathan/tmp/tmp.VdDNi49u8X/install/llvm/bad/bin/clang-16+0x282dc64)
  #39 0x00007f04d3bb1290 (/usr/lib/libc.so.6+0x23290)
  #40 0x00007f04d3bb134a __libc_start_main (/usr/lib/libc.so.6+0x2334a)
  #41 0x000056317b9c40a5 _start /build/glibc/src/glibc/csu/../sysdeps/x86_64/start.S:117:0
  clang-16: error: clang frontend command failed with exit code 134 (use -v to see invocation)
  ClangBuiltLinux clang version 16.0.0 (https://github.com/llvm/llvm-project b4e1466c35d3ca3e04244e8e8b4ffaf0784d6d37)
  Target: aarch64-unknown-linux-gnu
  Thread model: posix
  InstalledDir: /home/nathan/tmp/tmp.VdDNi49u8X/cvise/../install/llvm/bad/bin
  clang-16: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.

Repository:
  rG LLVM Github Monorepo

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