Suppose I have the following set up in my IR file:

Some main function that uses some api FUNCTION_CALLER to fork and call some FUNCTION

define dso_local noundef i32 @main() #0 !dbg !265 {
entry:
  (...)
  %a = alloca i32, align 4
  (...)
  call void @llvm.dbg.declare(metadata ptr %a, metadata !267, metadata !DIExpression()), !dbg !268
  (...)
  call void (ptr, i32, ...) @__FUNCTION_CALLER(..., ptr @.FUNCTION., ptr %a, ...), !dbg !275
  (...)

with relevant variable metadata:

!267 = !DILocalVariable(name: "a", scope: !265, file: !2, line: 23, type: !17)
!268 = !DILocation(line: 23, column: 7, scope: !265)

And FUNCTION looks like:

define internal void @.FUNCTION.(..., ptr noundefalign 4 dereferenceable(4) %a, ...) #2 !dbg !302 {
entry:
  (...)
  %a.addr = alloca ptr, align 8
  (...)
  store ptr %a, ptr %a.addr, align 8
  call void @llvm.dbg.declare(metadata ptr %a.addr, metadata !308, metadata !DIExpression()), ...
                                                                                     ... !dbg !306
  (...)

also with relevant variable metadata:

!308 = !DILocalVariable(name: "a", arg: 3, scope: !302, type: !284, flags: DIFlagArtificial)

Now, assume using C++ LLVM API, inside of FUNCTION I am investigating the Instruction* @llvm.dbg.declare. If I want to take a look at the metadata of %a.addr, the second argument, this brings me to !308. However, this doesn’t contain the information I want which is line number and column number in source declaration — this only shows up in the main function @llvm.dbg.declare because it’s not a pointer.

Is there a way, given the argument %a.addr with metadata at !308, I can trace it back to the for %a with metadata at !267/!268 at the original @llvm.dbg.declare?

To reiterate, how can I sort of dereference %a.addr to arrive at metadata for %a in my LLVM Pass, so I can get its line and column information?

I have tried something like going from %a.addr -> store ptr %a, ptr %a.addr, align 8 -> %a and then trace it back through FUNCTION‘s arguments, but this I’m not sure if this even works.