[libcxx-commits] [PATCH] D123580: [libc++] Use bit field for checking if string is in long or short mode
Nikolas Klauser via Phabricator via libcxx-commits
libcxx-commits at lists.llvm.org
Tue Apr 19 03:45:46 PDT 2022
philnik added inline comments.
Comment at: libcxx/utils/gdb/libcxx/printers.py:192
"""Print a std::string."""
> philnik wrote:
> > jgorbe wrote:
> > > Mordante wrote:
> > > > philnik wrote:
> > > > > Mordante wrote:
> > > > > > philnik wrote:
> > > > > > > Mordante wrote:
> > > > > > > > Does this also break the LLDB pretty printer?
> > > > > > > Probably. Would be nice to have a test runner for that.
> > > > > > I already planned to look into that, D97044#3440904 ;-)
> > > > > Do you know where I would have to look to know what the LLDB pretty printers do?
> > > > Unfortunately no. @jingham seems to be the Data formatter code owner.
> > > There was a recent lldb change fixing prettyprinters after a similar change to string: https://github.com/llvm/llvm-project/commit/45428412fd7c9900d3d6ac9803aa7dcf6adfa6fe
> > >
> > > If the gdb prettyprinter needed fixing for this change, chances are that lldb will need a similar update too.
> > Could someone from #lldb help me figure out what to change in the pretty printers? I looked at the file, but I don't really understand how it works and TBH I don't really feel like spending a lot of time figuring it out. If nobody says anything I'll land this in a week.
> > As a side note: it would be really nice if there were a few more comments inside `LibCxx.cpp` to explain what happens there. That would make fixing the pretty printer a lot easier. The code is probably not very hard (at least it doesn't look like it), but I am looking for a few things that I can't find and I have no idea what some of the things mean.
> Looks like something around https://github.com/llvm/llvm-project/blob/2e6ac54cf48aa04f7b05c382c33135b16d3f01ea/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp#L597 (& the similar masking in the `else` block a few lines down) - I guess a specific lookup for the new field would be needed, rather than the bitmasking.
Yes, but what do the numbers in `size_mode_locations` mean? Why is there no checking if it's big or little endian? Is it unsupported maybe? Does it work because of something else? Is there a reason that `g_data_name` exists instead of comparing directly? Should I add another layout style or should I just update the code for the new layout?
I don't know anything about the LLDB codebase, so I don't understand the code and I don't know how I should change it.
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