[llvm-dev] bug in the LiveDebugValues code?

[Andrew Kelley via llvm-dev]

Here is LLVM IR code:
https://gist.github.com/andrewrk/041af662b3ff515cd0be64ab85c112d7

That produces the following valgrind message:
$ valgrind llc -filetype=obj bug.ll

==27195== Conditional jump or move depends on uninitialised value(s)
==27195==    at 0x56A0917: (anonymous
namespace)::LiveDebugValues::transferDebugValue(llvm::MachineInstr const&,
(anonymous namespace)::LiveDebugValues::OpenRangesSet&,
llvm::UniqueVector<(anonymous namespace)::LiveDebugValues::VarLoc>&) [clone
.isra.207] (in
/nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x56A3EE5: (anonymous
namespace)::LiveDebugValues::ExtendRanges(llvm::MachineFunction&) [clone
.constprop.259] (in
/nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x57214A0:
llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (in
/nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x55CDF01:
llvm::FPPassManager::runOnFunction(llvm::Function&) (in
/nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x55CE29A: llvm::FPPassManager::runOnModule(llvm::Module&)
(in /nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x55CDB4E:
llvm::legacy::PassManagerImpl::run(llvm::Module&) (in
/nix/store/06dpmfn74zrmman8nq8p96dg50lwbxhg-llvm-3.9.0-lib/lib/
libLLVM-3.9.so)
==27195==    by 0x41C0B7: compileModule(char**, llvm::LLVMContext&) [clone
.constprop.385] (in
/nix/store/jis8r9v01xz357h3b39sqym8rls3h6nj-llvm-3.9.0/bin/llc)
==27195==    by 0x412D3F: main (in
/nix/store/jis8r9v01xz357h3b39sqym8rls3h6nj-llvm-3.9.0/bin/llc)

This is in llvm 3.9.0.

I found this while troubleshooting what I now to believe to be a separate
issue in my frontend code that caused LLVM to go into an infinite loop
writing into a .o file. When I ran that IR code against llc, I got "error:
initializer with struct type has wrong # elements" which LLVMVerifyModule
did not catch. I can provide this example IR as well if wanted.

Regards,
Andrew
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