[compiler-rt] [llvm-cov] Add --debug-info flag to llvm-cov to lookup debug info file. (PR #66798)

[Daniel Thornburgh via llvm-commits]

mysterymath wrote:

> > > Should this be able to work implicitly, same as a debugger? (presumably there's some logic (both as a concept, but concretely as code in lldb or somewhere similar) that knows how to find dsyms when they're in some standard layout (presumably `binary_name` has `binary_name.dsym` next to it, maybe some search path too)) Not sure if the debugger even has a way to explicitly tell it where a dsym is - and if it doesn't, probably not suitable to add such a thing to other debug info-consuming tools?
> > 
> > 
> > Yes, and `llvm-cov` already supports it through the `BuildIDFetcher` interface that @mysterymath created, we just need to wire it up.
> 
> Should we do that ("wire it up") instead of this patch, or is this patch part of that, or is there some motivation to do both?

The whole BuildIDFetcher mechanism depends on the object being available for lookup via its build ID; it's common for linkers to stamp binaries in this way, but usually some specific setup has to be done to actually place the files there. So it seems somewhat orthogonal to a flag that allows directly pointing to a file.

https://github.com/llvm/llvm-project/pull/66798