Hello,
I am editing the LowerTypeTests pass in LLVM, and part of my additions include the following 3 lines of code:
// newTypeName is a std::string
MDString* newMD = MDString::get(M.getContext(), newTypeName);
ArrayRef<Metadata*> mdArray {ConstantInt::get(Int64Ty, 0), newMD};
auto* node = MDTuple::get(M.getContext(), mdArray);
Thus far, I have been developing on a version of Clang with debugging symbols enabled, and this code has worked. However, on the Release+Asserts version, the third line results in a segmentation fault. The backtrace for the error, up to the method I’m working on, is as follows:
// signal handling…
#4 0x00005556e48d6120 llvm::ReplaceableMetadataImpl::getOrCreate(llvm::Metadata&) (/home/sjessu/build-no-debug/bin/clang-10+0x2787120)
#5 0x00005556e48db8c2 llvm::MetadataTracking::track(void*, llvm::Metadata&, llvm::PointerUnion<llvm::MetadataAsValue*, llvm::Metadata*>) (/home/sjessu/build-no-debug/bin/clang-10+0x278c8c2)
#6 0x00005556e48dbc12 llvm::MDNode::MDNode(llvm::LLVMContext&, unsigned int, llvm::Metadata::StorageType, llvm::ArrayRefllvm::Metadata*, llvm::ArrayRefllvm::Metadata*) (/home/sjessu/build-no-debug/bin/clang-10+0x278cc12)
#7 0x00005556e48dd70d llvm::MDTuple::getImpl(llvm::LLVMContext&, llvm::ArrayRefllvm::Metadata*, llvm::Metadata::StorageType, bool) (/home/sjessu/build-no-debug/bin/clang-10+0x278e70d)
#8 0x00005556e4a4b293 (anonymous namespace)::LowerTypeTestsModule::lower() (.part.1843) (/home/sjessu/build-no-debug/bin/clang-10+0x28fc293)
Crucially, this error does not occur in the Debug version, so I am lost as to how to diagnose it. I have checked that newMD is non-null and contains the value I expect. Are there any discrepancies in the Debug version as compared to the Release + Asserts version that would cause such an error? Thanks for your help!
Best,
Shishir Jessu