[llvm-dev] GDB pretty printers for LLVM ADTs

[David Blaikie via llvm-dev]

Good point - any ideas on where in the programmer's manual would suit best?
Looking around I sort of feel like it belongs in the "Picking the right
data structure" section - but I fear someone merely examining existing data
structures might not think to look there for help in their task (if they
have no need to 'pick' a data structure for a new use, etc).

On Mon, Dec 19, 2016 at 2:47 AM Piotr Padlewski <piotr.padlewski at gmail.com>
wrote:

> Excellent. I think it would make sense to add small section somewhere in
> documentation (e.g. LLVM Programmer’s Manual
> <http://llvm.org/docs/ProgrammersManual.html>) about it, so it won't be
> lost somewhere in the mailing list.
>
> Piotr
>
> 2016-12-17 1:04 GMT+01:00 David Blaikie via llvm-dev <
> llvm-dev at lists.llvm.org>:
>
> Added some basic DenseMap support in r290011
>
> On Fri, Dec 16, 2016 at 2:05 PM David Blaikie <dblaikie at gmail.com> wrote:
>
> I've added a few LLVM GDB pretty printers a while back (& just added
> llvm::Optional earlier today) & thought people might be interested in how
> to use them, etc.
>
> I use them by adding the following to my .gdbinit:
>
>   source /path/to/llvm/src/utils/gdb-scripts/prettyprinters.py
>
> Also, I can suggest adding:
>
>   set print pretty on
>
> there too, it helps a lot when printing complex nested data structures.
>
> Once you have that, you can get pretty output like this:
>
> (gdb) p Abbrev->AbbrDeclSets
> $1 = std::map with 1 elements = {
>   [0] = {
>     Offset = 0,
>     FirstAbbrCode = 1,
>     Decls = std::vector of length 1, capacity 1 = {{
>         Code = 1,
>         Tag = llvm::dwarf::Tag::DW_TAG_compile_unit,
>         CodeByteSize = 1 '\001',
>         HasChildren = false,
>         AttributeSpecs = llvm::SmallVector of length 8, capacity 8 = {{
>             Attr = llvm::dwarf::Attribute::DW_AT_low_pc,
>             Form = llvm::dwarf::Form::DW_FORM_addr,
>             ByteSize = llvm::Optional is not initialized
>           }, {
>             Attr = llvm::dwarf::Attribute::DW_AT_high_pc,
>             Form = llvm::dwarf::Form::DW_FORM_data8,
>             ByteSize = llvm::Optional is initialized = {
>               value = 8 '\b'
>             }
>
> Here you can see the pretty printers for SmallVector and Optional, but
> there's also support for StringRef, SmallString, and ArrayRef.
>
> I've tried doing a DenseMap pretty printer, but haven't quite figured it
> out yet (having trouble calling member functions to do some of teh more
> complicated parts of DenseMap iteration - may end up printing it with the
> tombstone/empty values present, but not sure how easy that'll be to read,
> etc). Happy to take requests or talk people through adding more pretty
> printers anyone wants to add :)
>
> Enjoy!
> - Dave
>
>
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