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

[David Blaikie]

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.

- 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/
>
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