Override new functions in DWOs.

I threaded dwarf_cu down to where it's really used and added the necessary check, so if it is nullptr, the fallback will be skipped.

Stray change.

Address comments.

Yes, you got the context right! Although technically speaking this change isn't limited to wasm, plugins can implement any vendor extension on top of this change.

Add unittest for DW_OP_addrx as well.

Bring back lost changes...

Add comments.

Full context with arcanist

Sorry for the missing context, I forgot that's manual!

Managed to add a unit test for the DW_OP_addr path!

I'm having some trouble coming up with a good test for this in the absence of a real wasm target. any suggestions appreciated!

In D97786#2974879, @dblaikie wrote:

Not fixable? Not sure I follow. In the case of cwd-relative (old behavior) you can fix the behavior by changing where you invoke the debugger from, and in the case of exe-relative you can fix the behavior by moving the executable? (once both source and dwo lookup is implemented consistently, at least)

In D97786#2973868, @dblaikie wrote:

This doesn't solve all use cases/it's not a terribly general purpose situation - using -fdebug-prefix-map/-fdebug-compilation-dir requires knowledge of these limitations/how to use these features together. (though I agree that changes in this area should apply to all relative comp_dir lookups - source and dwo files alike, rather than handling one group differently from the other when they're all defined as comp_dir relative)

This change breaks all existing uses of relative comp_dirs that don't accidentally make all of them relative to the executable's directory already.

Looks good to me as well, but please also get some feedback from Pavel.

Restore changes lost in previous patchset.

Rebase and improve testcase: The file can just be empty.

OP_deref would work if the structs are small enough. Leaving out OP_stack_value should just work. It's a terminator of sorts for values that aren't in memory, like registers on native or locals or globals in wasm land.

DW_OP_deref loads 32bit (64bit if the address size is 8), is that what's intended here? The struct passed by value could be bigger than that, couldn't it?

Replace binary test with an assembly test.

Read triple from first dwo file instead of from command line and add a test.

Thanks! Would you mind landing the change for me? I'm not a github comitter.

Add the new dwo sections to the testcase.