[PATCH] D125990: [LSR] Fix bug for optimizing unused IVs to final values

Wed Jul 6 12:42:39 PDT 2022

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

I bisected an assertion failure while building the Linux kernel for PowerPC to this patch:

  # bad: [20962c1240691d25b21ce425313c81eed0b1b358] [SimplifyCFG] Don't split predecessors of callbr terminator
  # good: [dc969061c68e62328607d68215ed8b9ef4a1e4b1] [SimplifyCFG] Thread all predecessors with same value at once
  git bisect start '20962c1240691d25b21ce425313c81eed0b1b358' 'dc969061c68e62328607d68215ed8b9ef4a1e4b1'
  # bad: [a6e63e35ede4b9f23b58437263eaac9a2926c9bf] [NFC][HLSL] Add tests for vector alias. Remove dead code.
  git bisect bad a6e63e35ede4b9f23b58437263eaac9a2926c9bf
  # good: [5493f8fc59ca9cc6fc14da8e6aafe6a52fb9ebc0] [VectorCombine] Improve shuffle select shuffle-of-shuffles
  git bisect good 5493f8fc59ca9cc6fc14da8e6aafe6a52fb9ebc0
  # bad: [b170d856a3a303ab826f6896812bfd0ce05ec706] [SimplifyCFG] Skip hoisting common instructions that return token type
  git bisect bad b170d856a3a303ab826f6896812bfd0ce05ec706
  # bad: [7b1ff859feaaf1316932d0be113d762626009fd6] [gn build] Port b8dbc6ffea93
  git bisect bad 7b1ff859feaaf1316932d0be113d762626009fd6
  # good: [a2158374ba1a6f81f4cce3eb54d0bc44f3ab75e0] [mlir][LLVMIR] Apply CallOp/CallableInterface on suitable operations
  git bisect good a2158374ba1a6f81f4cce3eb54d0bc44f3ab75e0
  # bad: [dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e] [LSR] Fix bug for optimizing unused IVs to final values
  git bisect bad dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e
  # good: [b8dbc6ffea93976dc0d8569c9d23e9c21e33e317] [HLSL] Add ExternalSemaSource & vector alias
  git bisect good b8dbc6ffea93976dc0d8569c9d23e9c21e33e317
  # first bad commit: [dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e] [LSR] Fix bug for optimizing unused IVs to final values

A simplified C reproducer:

  enum { true } typedef size_t;
  struct kernfs_node {
    struct kernfs_node *parent;
  } kernfs_path_from_node_locked_kn_to;
  size_t kernfs_path_from_node_locked___trans_tmp_1;
  void kernfs_path_from_node() {
    asm goto("" : : : : __label_warn_on);
  __label_warn_on:;
    struct kernfs_node *to = &kernfs_path_from_node_locked_kn_to;
    size_t depth;
    while (to) {
      depth++;
      to = to->parent;
    }
    kernfs_path_from_node_locked___trans_tmp_1 = depth;
  }

  $ clang --target=powerpc64-linux-gnu -O2 -c -o /dev/null dir.i
  clang: /home/nathan/cbl/src/llvm-project/llvm/include/llvm/IR/Instructions.h:2838: llvm::Value *llvm::PHINode::getIncomingValueForBlock(const llvm::BasicBlock *) const: Assertion `Idx >= 0 && "Invalid basic block argument!"' 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=powerpc64-linux-gnu -O2 -c -o /dev/null dir.i
  1.      <eof> parser at end of file
  2.      Code generation
  3.      Running pass 'Function Pass Manager' on module 'dir.i'.
  4.      Running pass 'Loop Pass Manager' on function '@kernfs_path_from_node'
  5.      Running pass 'Loop Strength Reduction' on basic block '%while.body'
   #0 0x000055926ab23473 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3445473)
   #1 0x000055926ab2140e llvm::sys::RunSignalHandlers() (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x344340e)
   #2 0x000055926aaa7893 (anonymous namespace)::CrashRecoveryContextImpl::HandleCrash(int, unsigned long) CrashRecoveryContext.cpp:0:0
   #3 0x000055926aaa7a0e CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
   #4 0x00007fbd976d8b90 __restore_rt (/lib64/libc.so.6+0x38b90)
   #5 0x00007fbd97728c4c __pthread_kill_implementation (/lib64/libc.so.6+0x88c4c)
   #6 0x00007fbd976d8ae6 gsignal (/lib64/libc.so.6+0x38ae6)
   #7 0x00007fbd976c27f4 abort (/lib64/libc.so.6+0x227f4)
   #8 0x00007fbd976c271b _nl_load_domain.cold (/lib64/libc.so.6+0x2271b)
   #9 0x00007fbd976d1696 (/lib64/libc.so.6+0x31696)
  #10 0x0000559269ca1c1d llvm::InductionDescriptor::isInductionPHI(llvm::PHINode*, llvm::Loop const*, llvm::ScalarEvolution*, llvm::InductionDescriptor&, llvm::SCEV const*, llvm::SmallVectorImpl<llvm::Instruction*>*) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x25c3c1d)
  #11 0x000055926abe97dc llvm::rewriteLoopExitValues(llvm::Loop*, llvm::LoopInfo*, llvm::TargetLibraryInfo*, llvm::ScalarEvolution*, llvm::TargetTransformInfo const*, llvm::SCEVExpander&, llvm::DominatorTree*, llvm::ReplaceExitVal, llvm::SmallVector<llvm::WeakTrackingVH, 16u>&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x350b7dc)
  #12 0x000055926a96f3d8 ReduceLoopStrength(llvm::Loop*, llvm::IVUsers&, llvm::ScalarEvolution&, llvm::DominatorTree&, llvm::LoopInfo&, llvm::TargetTransformInfo const&, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::MemorySSA*) LoopStrengthReduce.cpp:0:0
  #13 0x000055926a99d154 (anonymous namespace)::LoopStrengthReduce::runOnLoop(llvm::Loop*, llvm::LPPassManager&) LoopStrengthReduce.cpp:0:0
  #14 0x0000559269efcaeb llvm::LPPassManager::runOnFunction(llvm::Function&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x281eaeb)
  #15 0x000055926a3a7197 llvm::FPPassManager::runOnFunction(llvm::Function&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x2cc9197)
  #16 0x000055926a3aec41 llvm::FPPassManager::runOnModule(llvm::Module&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x2cd0c41)
  #17 0x000055926a3a7ba5 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x2cc9ba5)
  #18 0x000055926b332f5d 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<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3c54f5d)
  #19 0x000055926b6eafde clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) CodeGenAction.cpp:0:0
  #20 0x000055926bfbafc4 clang::ParseAST(clang::Sema&, bool, bool) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x48dcfc4)
  #21 0x000055926b62d8f0 clang::FrontendAction::Execute() (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3f4f8f0)
  #22 0x000055926b5a1f5f clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3ec3f5f)
  #23 0x000055926b6e4682 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x4006682)
  #24 0x00005592696f6f4a cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x2018f4a)
  #25 0x00005592696f4cdf ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
  #26 0x000055926b423572 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
  #27 0x000055926aaa77a7 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x33c97a7)
  #28 0x000055926b4230cf 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/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3d450cf)
  #29 0x000055926b3e2dde clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3d04dde)
  #30 0x000055926b3e308e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3d0508e)
  #31 0x000055926b3ff030 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x3d21030)
  #32 0x00005592696f43a1 clang_main(int, char**) (/home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin/clang-15+0x20163a1)
  #33 0x00007fbd976c3550 __libc_start_call_main (/lib64/libc.so.6+0x23550)
  #34 0x00007fbd976c3609 __libc_start_main at GLIBC_2.2.5 (/lib64/libc.so.6+0x23609)
  #35 0x00005592696f1945 _start /build/glibc/src/glibc/csu/../sysdeps/x86_64/start.S:117:0
  clang-15: error: clang frontend command failed with exit code 134 (use -v to see invocation)
  ClangBuiltLinux clang version 15.0.0 (https://github.com/llvm/llvm-project dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e)
  Target: powerpc64-unknown-linux-gnu
  Thread model: posix
  InstalledDir: /home/nathan/tmp/install/llvm/dbf6ab5ef9ae0e1f4706917c2b3f98a67c35826e/bin
  clang-15: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.

At the parent commit, there is no crash.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D125990/new/

https://reviews.llvm.org/D125990