Get filename and location from Function - llvm

Question

I have an LLVM pass that iterates over LLVM IR code and I would like to get a directory and a filename for both the functions and basic blocks for the original code. I know that when I have an Instruction Pointer, I can easily get the information using the code below: Thanks to #hailinzeng
(How to get the filename and directory from a LLVM Instruction?)
const llvm::DebugLoc &location = i_iter->getDebugLoc();
if (location && debugLocationInfoOn) {
std::string dbgInfo;
llvm::raw_string_ostream rso(dbgInfo);
location.print(rso);
std::cout << rso.str();
}
However, since the class Function and BasicBlock do not have a member function getDebugLoc(), this doesn't work. I saw another post here using the metadata but I do not know how to get to the DILocation or DIScope from the metadata. Using
MDNode *n = inst->getMetadata("dbg");
DILocation loc(n); `
Gives the error below
/usr/lib/llvm-3.9/include/llvm/IR/Metadata.def:83:42: note: forward declaration of 'llvm::DILocation'
HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DILocation)
I'm using llvm 3.9.
UPDATE ::
Thanks Stanislav Pankevich. I wasn't including the right headers but now I have a new issue. DILocation requires LLVMContext, StorageType, and unsigned Line. How do I get the line number and and storage type from a function pointer?
DILocation(LLVMContext &C, StorageType Storage, unsigned Line,
For those working with a similar issue, you can get LLVMContext using
llvm::MDNode * testmd = F.getMetadata("dbg");
F.getContext ()

Answer 1

If you look at the .ll file for your code, you would see that every function has DINode associated with it, something like !<some_number>. That's the metadata node number that is has info about that function. The type of that node is DISubprogram You can access it like this:
SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
F.getAllMetadata(MDs);
for (auto &MD : MDs) {
if (MDNode *N = MD.second) {
if (auto *subProgram = dyn_cast<DISubprogram>(N)) {
errs() << subProgram->getLine();
}
}
}
You can use all the information that is there in the debug node.

Answer 2

How about if we want column details, which is not possible with DISubprogram.
I tried this:
DILocation *debugLocation = dyn_cast<DILocation>(N);
debugLocation->getLine();
The sample.ll file does contain these lines:
!10 = !DILocation(line: 1, column: 1, scope: !1)
However, it gives core dumped at run time. Any suggestions please how to get it working.