[llvm-dev] CodeView layering

[Zachary Turner via llvm-dev]

Note the same is true of DebugInfoMSF, and DebugInfoPDB (all of which are
related).

On Wed, Mar 21, 2018 at 1:34 PM Zachary Turner <zturner at google.com> wrote:

> DebugInfoCodeView is nto strictly a consumer, it is also a producer.
>
> On Wed, Mar 21, 2018 at 1:29 PM <paul.robinson at sony.com> wrote:
>
>> Intuitively I'd think MC and DebugInfo should be independent.  MC is a
>> producer, DebugInfo is a consumer.  What's common is the definition of the
>> structures they operate on, which doesn't properly belong to either one.
>>
>> --paulr
>>
>>
>>
>> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of *David
>> Blaikie via llvm-dev
>> *Sent:* Wednesday, March 21, 2018 11:52 AM
>> *To:* Zachary Turner
>> *Cc:* llvm-dev
>> *Subject:* Re: [llvm-dev] CodeView layering
>>
>>
>>
>> Someone internally's been dabbling with turning on some of Google's build
>> system's stricter header checking modes - and they caught these (you can
>> check the internal code review 184305506 for the original where I'm pulling
>> things out from).
>>
>> & yeah, fair question about the modules builds - I don't fully understand
>> what they catch and don't catch. I suspect it's a matter of whether the
>> headers themselves form a cycle - whereas the Google build system's a bit
>> more structured - knowing about libraries and explicit dependencies between
>> them.
>>
>> & I didn't look closely to see if, as I said, MC could depend on
>> DebugInfoCodeView - probably weird/awkward/not what we want (I'm guessing?)
>> but the modules buildbots don't have explicit dependencies, they just fail
>> when they find a cycle. So they can implicitly support all sorts of weird
>> dependencies we might not've expected/planned, so long as it's not an
>> actual cycle (& only within the headers - so the modules system might be
>> like "oh, sure, MC can depend on DebugInfoCodeView" but the library
>> dependency might be the exact opposite (some MC .cpp file could call into
>> DebugInfoCodeView & the modules build wouldn't fail - it knows nothing
>> about .cpp modularity/grouping, just headers))
>>
>>
>>
>> On Wed, Mar 21, 2018 at 11:42 AM Zachary Turner <zturner at google.com>
>> wrote:
>>
>> Yes, some of the headers and stuff that are just raw structure
>> definitions and enums could probably be sunk into BinaryFormat..
>>
>>
>>
>> How'd you find this?  Curious why it hasn't been breaking in modules
>> builds for a long time.
>>
>>
>>
>> On Wed, Mar 21, 2018 at 11:31 AM David Blaikie <dblaikie at gmail.com>
>> wrote:
>>
>> I'm looking at fixing some layering violations in LLVM & came across a
>> few in the CodeView handling, specifically:
>>
>> lib/MC/MCCodeView includes several llvm/DebugInfo/CodeView headers
>>   I guess MC could be made dependent on DebugInfoCodeView? But probably
>> these things should be sunk into BinaryFormat as is the case for DWARF
>> features used by MC?
>>
>> include/llvm/Object/COFF.h includes
>> include/llvm/DebugInfo/CodeView/CVDebugRecord.h
>>   Also seems like this could/should/needs to be sunk into BinaryFormat?
>>
>> I'm open to ideas & happy to do the work, or help in any way that might
>> be useful.
>>
>> Thanks,
>> - Dave
>>
>>
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