[PATCH] LLD: Remove YAML/Native round-trip passes

Rafael EspĂ­ndola rafael.espindola at gmail.com
Thu Feb 19 17:50:59 PST 2015

On 19 February 2015 at 19:41, Michael Spencer <bigcheesegs at gmail.com> wrote:
> On Wed, Feb 11, 2015 at 4:37 PM, Rui Ueyama <ruiu at google.com> wrote:
>> I found that Writing and reading Native files from YAML reader is actually
>> tricky. Readers generally don't need a linking context, but writers do. So
>> it's not easy to call a writer from a reader. Seems it needs a plumbing
>> work.
>> Then I tried to convert a YAML file to Native using yaml2obj -format=native.
>> yaml2obj didn't actually support Native format because Native format lives
>> only in LLD. Yet it's intended to be an alternative, hopefully better object
>> file format, it's not supported by anyone except the linker. There's no
>> consumer producing a file in that file format.
> We haven't taught clang to produce it yet because the format isn't
> finalized. The performance gain from it is still rather large, and I
> feel it's an important feature.

Please note that we don't have evidence of this yet.

I would be very opposed to adding a new file format to llvm proper until

* lld is production quality
* lld is as fast as gold on ELF
* there is experimental evidence that a new format would make it even
faster without compromising its ability to report errors.


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