[PATCH] Add a DIExternalTypeRef debug metadata node to the IR.

[David Blaikie]

On Fri, May 8, 2015 at 12:58 PM, Adrian Prantl <aprantl at apple.com> wrote:

>
> On May 8, 2015, at 12:32 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Fri, May 8, 2015 at 11:18 AM, Adrian Prantl <aprantl at apple.com> wrote:
>
>> Hi dexonsmith, dblaikie, echristo,
>>
>> This adds a DIExternalTypeRef debug metadata node to the IR that is meant
>> to be emitted by Clang when referring to a type that is defined in a .pcm
>> file. DIExternalTypeRef is a child of DICompositeTypeBase because it shares
>> common traits such as the unique identifier.
>>
>
> Could this be an attribute to the DIClassType/StructureType? (to emit the
> currently needed type unit references, we still should know the correct
> class/structure type tag) LLVM already knows to hash the ref identifier
> (mangled name) for the type unit identifier.
>
>
> That would rule out using it for other kinds of types such as subroutine
> types (probably not so important) and typedef types (maybe as bit more so).
>

Might be worth waiting until we're dealing with Bag O' DWARF before we do
that. At that point we'll want to refer to non-type things (like member
function declarations).


>
> -- adrian
>
>
> - David
>
>
>>
>> The idea how this is going to be used is that the frontend will discover
>> that a type originates from an AST file and instead of and constructing a
>> full DIType (and thus deserializing the type from the AST) it creates a
>> DIExternalTypeRef with the tag type, mangled name and the .pcm file. The
>> backend then can emit this as a split-DWARF-style forward declaration using
>> DW_FORM_ref_sig8 (GDB) or as a string reference (LLDB) + and accelerator
>> table entry.
>>
>> REPOSITORY
>>   rL LLVM
>>
>> http://reviews.llvm.org/D9612
>>
>> Files:
>>   include/llvm/Bitcode/LLVMBitCodes.h
>>   include/llvm/IR/DIBuilder.h
>>   include/llvm/IR/DebugInfoMetadata.h
>>   include/llvm/IR/Metadata.def
>>   include/llvm/IR/Metadata.h
>>   lib/AsmParser/LLParser.cpp
>>   lib/Bitcode/Reader/BitcodeReader.cpp
>>   lib/Bitcode/Writer/BitcodeWriter.cpp
>>   lib/IR/AsmWriter.cpp
>>   lib/IR/DIBuilder.cpp
>>   lib/IR/DebugInfoMetadata.cpp
>>   lib/IR/LLVMContextImpl.h
>>   lib/IR/Verifier.cpp
>>   test/Assembler/DIExternalTypeRef.ll
>>
>> EMAIL PREFERENCES
>>   http://reviews.llvm.org/settings/panel/emailpreferences/
>>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150508/f0dab215/attachment.html>