[LLVMdev] First-class debug info IR: MDLocation (original) (raw)

Duncan P. N. Exon Smith dexonsmith at apple.com
Mon Oct 27 09:22:27 PDT 2014

On 2014-Oct-24, at 16:37, David Blaikie <dblaikie at gmail.com> wrote:

Notice that only the links to parents (i.e., context:) are explicit here -- backlinks are implied. For example, !7 and !8 point to !6, but not the reverse. This may be a problem - the difference between nodes in a structure/classtype's member list, and those that are not in the member list but refer to the class/structure as their parent is meaningful. Type units use this distinction to avoid emitting instantiation-specific data into the canonical type unit (nested classes, implicit special members, member template instantiations, etc). Not sure what the right answer will be there.

Interesting. Could we model that with a Boolean flag on the child?

Also, would there be value in modelling type units more explicitly in the IR?

Presumably when dumping the fields will come in a specific, defined order? (probably not preserving the original source order, etc) Variation there would probably make checking harder than it needs to be.

Right.

Would it be possible to omit the names of unreferenced nested metadata? (if you have a bunch of member functions in a class, but don't need to refer to them elsewhere (eg: those member functions aren't defined in this translation unit)) - that'd help readability/writeability, but probably wouldn't impact FileCheck.

Certainly possible, but is it generally desirable? I guess we'll sort that out when I get there.

Also the whole "metadata " prefix on anything is a bit verbose, if we can omit that in some/many places, that'll help reduce the visual noise/improve readability/writeability. But most/all of that I imagine is fairly easily incremental change/improvement, nothing fundamental that needs to be chosen up-front.

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