Re: [PATCH 1/4] New gdb arch hook: return_with_first_hidden_param_p

Joel Brobecker
2012-05-16T15:31:57Z

> My original words are "My point is if we only examine debug info, we
> don't know whether hidden parameter is passed, because the debug info is
> the same". The "same" means compiler doesn't generate DIE for the
> hidden parameter, so it is the same on the targets having hidden
> parameter passed and the targets not having hidden parameter passed.

I was confusing the nameless, artificial, DIE that's generated as one
of the parameters of the subroutine as the DIE associated to that
hidden parameters. What's that nameless+artificial parameter DIE, then?

Talking to Tom on IRC, he reminded me that this issue is something
ABI-related, and thus wouldn't show up in DWARF debug info. Your
last email seems to indicate that this would be correct.

Now, because I don't know the C++ ABI at all, I don't know whether
it is expected that some architectures would have a hidden parameter
for the return value, while some don't. Is that allowed? Regardless,
it sounds like a gdbarch method would the logical approach... If
that is the case, I'd rather someone with more knowledge with C++
did the actual review, because I wouldn't be able to say whether
the implementation makes sense or not.

--
Joel