[lld] r222983 - [Core] Add flag to check if RoundTripPasses need to be run.

[Shankar Easwaran]

On 12/1/2014 4:02 PM, Rui Ueyama wrote:
> On Mon, Dec 1, 2014 at 1:48 PM, Nick Kledzik <kledzik at apple.com> wrote:
>
>> On Dec 1, 2014, at 12:34 PM, Rui Ueyama <ruiu at google.com> wrote:
>>
>> That sounds like we really need a new property of Atom.
>>
>> 1. If we run LLD in Release build, the roundtrip passes don't run, so
>> everything works fine.
>> 2. If we run LLD in Debug build (and from the unit tests), the information
>> is dropped during the round-trip conversion, and it fails.
>> 3. RoundTrip tests should't drop any information.
>>
>> 2 and 3 conflicts.
>>
>>
>> I have a different view.
>>
>> I think of those Passes as a quick way to exercise the YAML and native
>> formats.  The mechanism is as if you went through the test cases and added
>> a line which ran “ld -r” to merge all input files into one file, then ran
>> the rest of the test with that merged input file.  That works everywhere
>> except in tests that care about the name of the input file (which is now
>> changed).  So, for those cases you would not do the merge step.  But since
>> the round trip is implicit, there is no way to turn it off.  Shankar is
>> adding a way to turn it off.
>>
> That doesn't sounds like a different view.
>
> If a test fails because of the difference of an input file name, not
> because the round-trip conversion drops some information, we should disable
> the round-trip test only for that test. Now I feel I understood your
> suggestion in a different thread. Is there any way to override the
> environment variable in the lit test? Does it allow us to write RUN:
> LLD_ROUNDTRIP_TEST=0 lld <args here> ?

The filename information of the Atom is lost in the Native format.

Gnu flavor needs the filename whenever the user uses a linker script (or) the user decides to know the memory map of the image.

So this is needed almost all the time.

Shankar Easwaran

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