[clang] [llvm] Add option to generate additional debug info for expression dereferencing pointer to pointers. (PR #81545)

[David Blaikie via cfe-commits]

dwblaikie wrote:

Reading LLVM IR lit CHECK lines from clang codegen is a bit difficult - could you include some simple examples (perhaps from the new clang tests in this patch) showing the DWARF output just as comments in this review for something more easily glanceable?

As for flags - I assume this will be way too expensive (do you have some numbers, eg: for a clang build inside google in a release config, or at least optimizations+debug info) to enable by default where we currently enable debug info and debug-info-for-profiling.

I'd expect this to be a fairly experimental feature - that it might not be feasible to make this compact enough to enable by default/maybe it's just infeasible to make this compact enough at all at which point we'd want to remove all this functionality. So maybe it goes under a -Xclang/cc1 flag only to start with, to allow exploration/experimentation, but with the expectation that folks won't depend on this until/unless it's able to be made compact enough.

https://github.com/llvm/llvm-project/pull/81545