[llvm-dev] CodeView layering

[David Blaikie via llvm-dev]

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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