[PATCHs] Using the MC layer to produce dSYM companion binaries

[Pete Cooper via llvm-commits]

Hey Fred

Sorry this took so long, especially for a cleanup.  LGTM.

Cheers,
Pete

On 7 August 2015 at 12:50, Frédéric Riss <friss at apple.com> wrote:

>
> On Aug 7, 2015, at 12:12 PM, Pete Cooper <pete.cooper at gmail.com> wrote:
>
> Hey Fred
>
> The first patch is fine.  I've been investigating whether individual
> emitters for formats can have more control over the layout.  This patch is
> actually similar to what I was doing (for those interested, I was trying to
> see if laying out a function at a time on MachO would be a good idea as
> then the relocations in the function can be resolved immediately without
> creating fixups).
>
> The second patch appears to just be formatting.  I don't see the 'tad more
> generic' you mention.  The patch is itself good cleanup if you are going to
> be making more changes to the code anyway.
>
>
> Doh, looks like I sent out the result of git-format-patch rather than the
> actual patch… Here it is again (I hope)
>
>
>
> Ferd
>
> So LGTM on both counts.  Looking forward to the next patches to follow.
>
>
> Thanks!
>
> Cheers,
> Pete
>
> On 5 August 2015 at 08:24, Frédéric Riss <friss at apple.com> wrote:
>
>> Hi,
>>
>> I’m directly and indirectly using the MC layer to produce the content of
>> the debug sections in llvm-dsymutil. This works great, except that dsymutil
>> is supposed to produce dSYM companion binaries and not the simple object
>> files MC was designed to produce.
>>
>> At some point I contemplated making MC generic enough to emit these kind
>> of binaries, but it just feels like a bad fit. Moreover dSYM companion
>> binaries have a number of unique characteristics that I think would fit
>> pretty badly into any kind of generic framework (eg. fake sections that
>> have a size but no contents or VM layout without any loadable sections).
>>
>> I went the route of writing my own equivalent of the MCObjectWriter in
>> llvm-dsymutil which was easy enough. Today the layout of the sections and
>> the file emission is done inside MCAssembler::Finish(). For my usecase, I
>> want to run only the section layout and do the emission myself. The first
>> attached patch allows that by splitting a layout(MCAsmLayout &) method out
>> of MCAssembler::Finish(). Does this look reasonable?
>>
>> I also tried to reuse some low-level MachObjectWriter primitives. The
>> second patch attached allows me to do just that by making them a tad more
>> generic.
>>
>> Both patches should have NFC.
>>
>>
>>
>>
>>
>>
>>
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>
>
>
>
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