[PATCH] D40917: Emit .debug$H section in clang

[David Blaikie via llvm-commits]

15% increase in object size is pretty huge (at least in the world I'm
working in, which is admittedly rather different than yours). By untested I
meant end-to-end, sorry, should've been clear. Like "not
demonstrated/used/useful" (for someone who uses the compiler today).

On Mon, Dec 11, 2017 at 10:43 AM Zachary Turner <zturner at google.com> wrote:

> I think there is a decent amount of test coverage provided by this and
> previous patches.  Was there some other kind of test coverage you had in
> mind?  I toyed with the idea of putting it behind an option, but it seemed
> unnecessary since there is no real disadvantage to having the extra data in
> there, aside from a relatively small increase in build size.
>
> On Mon, Dec 11, 2017 at 10:37 AM David Blaikie <dblaikie at gmail.com> wrote:
>
>> Seems a bit surprising to me to implement this as on by default while
>> it's unused and untested - I'd expect an extra flag during such an
>> experimental phase?
>>
>> On Wed, Dec 6, 2017 at 12:59 PM Zachary Turner via Phabricator via
>> llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>
>>> zturner created this revision.
>>> Herald added subscribers: JDevlieghere, hiraditya, mgorny.
>>>
>>> This causes emission of .debug$H section unconditionally when
>>> `-gcodeview` is present.
>>>
>>> I ran some benchmarks on a self-hosted build and found a ~2% increase in
>>> overall build time (within the margin of error, so basically noise), and a
>>> ~15% increase in object file size, on average.
>>>
>>> Currently the linker doesn't use this, that will work will come in a
>>> followup patch.  For now, we're just testing that clang emits it correctly
>>> with some obj2yaml and llc based tests.
>>>
>>>
>>> https://reviews.llvm.org/D40917
>>>
>>> Files:
>>>   llvm/include/llvm/DebugInfo/CodeView/GlobalTypeTableBuilder.h
>>>   llvm/include/llvm/DebugInfo/CodeView/TypeHashing.h
>>>   llvm/include/llvm/MC/MCObjectFileInfo.h
>>>   llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
>>>   llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
>>>   llvm/lib/DebugInfo/CodeView/CMakeLists.txt
>>>   llvm/lib/DebugInfo/CodeView/GlobalTypeTableBuilder.cpp
>>>   llvm/lib/MC/MCObjectFileInfo.cpp
>>>   llvm/lib/ObjectYAML/CodeViewYAMLTypeHashing.cpp
>>>   llvm/test/DebugInfo/COFF/global-type-hashes.ll
>>>   llvm/test/DebugInfo/COFF/globals.ll
>>>
>>> _______________________________________________
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>>> llvm-commits at lists.llvm.org
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>>>
>>
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