[PATCH] Add a DWOId field to DICompileUnit (so DWARF skeleton CUs can be expression in IR).

[Duncan P. N. Exon Smith]

> On 2015 May 4, at 20:17, Adrian Prantl <aprantl at apple.com> wrote:
> 
> Now with autoupgrade testcase.
> 
> 
> http://reviews.llvm.org/D9488
> 
> Files:
>  include/llvm/IR/DIBuilder.h
>  include/llvm/IR/DebugInfoMetadata.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
>  test/Assembler/mdcompileunit.ll
>  test/Bitcode/DICompileUnit-upgrade.test
>  test/Bitcode/Inputs/DICompileUnit-no-DWOId.bc
>  unittests/IR/MetadataTest.cpp
> 
> EMAIL PREFERENCES
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> <D9488.24927.patch>

LGTM with some changes to the autoupgrade test.

> Index: test/Bitcode/DICompileUnit-upgrade.test
> ===================================================================
> --- /dev/null
> +++ test/Bitcode/DICompileUnit-upgrade.test

Can you be more descriptive?  Perhaps dicompileunit-no-dwoid.ll.
(Feel free to use the camel-case filename; I personally avoid
capitals but clearly there's no harm.)

> @@ -0,0 +1,6 @@
> +RUN: llvm-dis %p/Inputs/DICompileUnit-no-DWOId.bc -o - | FileCheck %s

%p was undocumented last I checked.  I recommend the documented %S
when this sort of functionality is necessary.

But I wouldn't even use the `Inputs` folder here.  The usual bitcode
upgrade tests say:

    ; RUN: llvm-dis < %s.bc | FileCheck %s
    ; RUN: verify-uselistorder < %s.bc

and just drop a .ll.bc file next to a .ll test in `test/Bitcode`.

Moreover, the test file should be the `.ll` file that was used to
generate the bitcode.  Please add a comment that says what revision of
LLVM was used to generate the bitcode, something like:

    ; Bitcode generated from llvm-as @ r123456.

> +The input uses the older form without a dwoId field.
> +This should default to 0,
> +which is not displayed at all in the textual representation.
> +CHECK: !DICompileUnit
> +CHECK-NOT: dwoId: