[LLVMbugs] [Bug 24141] New: Clang asserts with -menable-unsafe-fp-math

[bugzilla-daemon at llvm.org]

https://llvm.org/bugs/show_bug.cgi?id=24141

            Bug ID: 24141
           Summary: Clang asserts with -menable-unsafe-fp-math
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: rtrieu at google.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Reproduction:
struct pair {
  double first;
  double second;
  pair() : first(0), second(0) {}
};

static pair ReturnPair(double x) {
  double Dnext = 1 + (2) * x;
  return pair();
}

void Run() {
  double x = 0;
  while (true) {
    pair Q = ReturnPair(x);
    double step =  Q.first / Q.second;
    x -= step;
  }
}

Command line:
clang -cc1 -emit-obj -O1 -menable-unsafe-fp-math foo.cpp

Cause:
SelectionDAG::getNode is called with a null pointer for the N1 parameter, which
the function assumes is non-null.  The actual assert is triggered inside
casting code when N1 is the argument to a dyn_cast.

Stack dump:
0.    Program arguments: clang -cc1 -emit-obj -O1 -menable-unsafe-fp-math
foo.cpp 
1.    <eof> parser at end of file
2.    Code generation
3.    Running pass 'Function Pass Manager' on module 'foo.cpp'.
4.    Running pass 'X86 DAG->DAG Instruction Selection' on function '@_Z3Runv'
Aborted (core dumped)

clang: ../include/llvm/Support/Casting.h:81: static bool
llvm::isa_impl_cl<llvm::ConstantSDNode, llvm::SDNode *>::doit(const From *) [To
= llvm::ConstantSDNode, From = llvm::SDNode *]: Assertion `Val && "isa<> used
on a null pointer"' failed.
#0 0x16801ad llvm::sys::PrintStackTrace(llvm::raw_ostream&)
(/usr/local/bin/clang-3.5+0x16801ad)
#1 0x16815bb SignalHandler(int) (/usr/local/bin/clang-3.5+0x16815bb)
#2 0x7f988f1c3340 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10340)
#3 0x7f988e6efcc9 gsignal
/build/buildd/eglibc-2.19/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
#4 0x7f988e6f30d8 abort /build/buildd/eglibc-2.19/stdlib/abort.c:91:0
#5 0x7f988e6e8b86 __assert_fail_base
/build/buildd/eglibc-2.19/assert/assert.c:92:0
#6 0x7f988e6e8c32 (/lib/x86_64-linux-gnu/libc.so.6+0x2fc32)
#7 0x1bc28ff llvm::SelectionDAG::getNode(unsigned int, llvm::SDLoc, llvm::EVT,
llvm::SDValue, llvm::SDValue, llvm::SDNodeFlags const*)
(/usr/local/bin/clang-3.5+0x1bc28ff)
#8 0x1b3a474 (anonymous namespace)::DAGCombiner::visit(llvm::SDNode*)
(/usr/local/bin/clang-3.5+0x1b3a474)
#9 0x1b2186c (anonymous namespace)::DAGCombiner::combine(llvm::SDNode*)
(/usr/local/bin/clang-3.5+0x1b2186c)
#10 0x1b20dcd llvm::SelectionDAG::Combine(llvm::CombineLevel,
llvm::AliasAnalysis&, llvm::CodeGenOpt::Level)
(/usr/local/bin/clang-3.5+0x1b20dcd)
#11 0x1c39a50 llvm::SelectionDAGISel::CodeGenAndEmitDAG()
(/usr/local/bin/clang-3.5+0x1c39a50)
#12 0x1c392c8 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function
const&) (/usr/local/bin/clang-3.5+0x1c392c8)
#13 0x1c35fe4
llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&)
(/usr/local/bin/clang-3.5+0x1c35fe4)
#14 0xdb9b81 (anonymous
namespace)::X86DAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&)
(/usr/local/bin/clang-3.5+0xdb9b81)
#15 0x10b460c llvm::MachineFunctionPass::runOnFunction(llvm::Function&)
(/usr/local/bin/clang-3.5+0x10b460c)
#16 0x1339fd4 llvm::FPPassManager::runOnFunction(llvm::Function&)
(/usr/local/bin/clang-3.5+0x1339fd4)
#17 0x133a20b llvm::FPPassManager::runOnModule(llvm::Module&)
(/usr/local/bin/clang-3.5+0x133a20b)
#18 0x133a6f5 llvm::legacy::PassManagerImpl::run(llvm::Module&)
(/usr/local/bin/clang-3.5+0x133a6f5)
#19 0x177d725 clang::EmitBackendOutput(clang::DiagnosticsEngine&,
clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions
const&, llvm::StringRef, llvm::Module*, clang::BackendAction,
llvm::raw_pwrite_stream*) (/usr/local/bin/clang-3.5+0x177d725)
#20 0x1cf2965 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&)
(/usr/local/bin/clang-3.5+0x1cf2965)
#21 0x201f703 clang::ParseAST(clang::Sema&, bool, bool)
(/usr/local/bin/clang-3.5+0x201f703)
#22 0x1a4cef2 clang::FrontendAction::Execute()
(/usr/local/bin/clang-3.5+0x1a4cef2)
#23 0x1a1d07c clang::CompilerInstance::ExecuteAction(clang::FrontendAction&)
(/usr/local/bin/clang-3.5+0x1a1d07c)
#24 0x1ac5dfc clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
(/usr/local/bin/clang-3.5+0x1ac5dfc)
#25 0x706394 cc1_main(llvm::ArrayRef<char const*>, char const*, void*)
(/usr/local/bin/clang-3.5+0x706394)
#26 0x70512e main (/usr/local/bin/clang-3.5+0x70512e)
#27 0x7f988e6daec5 __libc_start_main
/build/buildd/eglibc-2.19/csu/libc-start.c:321:0
#28 0x702173 _start (/usr/local/bin/clang-3.5+0x702173)

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