[LLVMdev] Module crash when adding CallInst

[David Blaikie]

Have you tried an asserts build of clang/llvm? If you're doing LLVM
development you should probably be using an asserts build.

I would guess you're hitting the issue where, if you have debug info for a
function, any call instructions inside that function must themselves have a
debug location (that !dbg thing). Otherwise bad debug info (and assertions
to ensure that badness doesn't happen) happens.

- David

On Tue, May 19, 2015 at 1:15 AM, Pankaj Kohli <pankaj208 at gmail.com> wrote:

> Hi,
>
> I am learning to write LLVM modules. I am using IRBuilder to insert calls
> to an existing function. The call is to be inserted at a random location in
> every function in the code. The call does get inserted, however, the module
> crashes later (after doFinalization()). The crash happens only sometimes,
> not always.
>
> These are the kind of instructions that I see in the generated code.
>   %callins = call void @myfunc(), !dbg !285
>   %callins = call void @myfunc()
>
> The stack trace shows the crash has something to do with debug
> information. Do I need to add metadata or debug info to the newly added
> call instruction? Any pointers on how I can do that?
>
> Here is the code snippet and the stack trace:
>
> IRBuilder<> Builder(ins); // to be inserted before ins
> CallInst *call = Builder.CreateCall(func, "callins"); // call to func
>
>
> 0  clang           0x0000000001492ec2
> llvm::sys::PrintStackTrace(_IO_FILE*) + 34
> 1  clang           0x0000000001490f61
> 2  libpthread.so.0 0x00002b33bd0ee340
> 3  clang           0x00000000016a43a6
> llvm::DwarfUnit::addString(llvm::DIE&, llvm::dwarf::Attribute,
> llvm::StringRef) + 22
> 4  clang           0x00000000016c2003
> llvm::DwarfCompileUnit::applyVariableAttributes(llvm::DbgVariable const&,
> llvm::DIE&) + 915
> 5  clang           0x000000000168bdfe
> llvm::DwarfDebug::finishVariableDefinitions() + 270
> 6  clang           0x0000000001690424
> llvm::DwarfDebug::finalizeModuleInfo() + 52
> 7  clang           0x000000000169c4a8 llvm::DwarfDebug::endModule() + 40
> 8  clang           0x00000000016850f7
> llvm::AsmPrinter::doFinalization(llvm::Module&) + 551
> 9  clang           0x00000000011befe5
> llvm::FPPassManager::doFinalization(llvm::Module&) + 69
> 10 clang           0x00000000011ca40d
> llvm::legacy::PassManagerImpl::run(llvm::Module&) + 813
> 11 clang           0x0000000001837fad
> clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::CodeGenOptions
> const&, clang::TargetOptions const&, clang::LangOptions const&,
> llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::raw_ostream*) +
> 1629
> 12 clang           0x000000000182a47f
> 13 clang           0x0000000001bdf043 clang::ParseAST(clang::Sema&, bool,
> bool) + 483
> 14 clang           0x0000000001603ba6 clang::FrontendAction::Execute() +
> 118
> 15 clang           0x00000000015e47b8
> clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 280
> 16 clang           0x0000000001673b41
> clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 1921
> 17 clang           0x0000000000820358 cc1_main(llvm::ArrayRef<char
> const*>, char const*, void*) + 1320
> 18 clang           0x00000000007fceaa main + 8298
> 19 libc.so.6       0x00002b33bdd56ec5 __libc_start_main + 245
> 20 clang           0x000000000081e5d9
>
> Any help is appreciated.
>
> Thanks,
> Pankaj
>
>
>
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