[PATCH] Do not use layout-before to layout atoms.

[Rui Ueyama]

Done.


On Thu, Mar 27, 2014 at 3:00 PM, Shankar Easwaran
<shankare at codeaurora.org>wrote:

>  Wow, I was unaware of this change that deadStrip was always enabled for
> PE/COFF with lld.
>
> LGTM then, Can we put a note in the code that kindLayoutBefore will be
> removed and used only by Dead stripping code to prevent atoms from being
> deadstripped.
>
> Thanks
>
> Shankar Easwaran
>
>
> On 3/27/2014 4:40 PM, Rui Ueyama wrote:
>
> Dead-stripping is enabled by default for PE/COFF because MSVC link.exe
> does it by default.
>
> On Thu, Mar 27, 2014 at 2:38 PM, Shankar Easwaran <shankare at codeaurora.org
> > wrote:
>
>>  I understand your usecase, but what I meant is, dead-strip is only a
>> option available in core.
>>
>> Removing kindLayoutBefore completely should not affect anything because
>> we dont dead strip in flavors [link, gnu, ld64]
>>
>> Thanks
>>
>> Shankar Easwaran
>>
>>
>> On 3/27/2014 4:31 PM, Rui Ueyama wrote:
>>
>>  Can you elaborate a bit? I don't understand what you mean.
>>
>>  Removing kindLayoutBefore will affect dead stripping because it would
>> lost back references for kindLayoutAfter, so it would collect live atoms.
>>
>>  I'm not removing kindLayoutBefore in this patch. This patch is just to
>> stop using kindLayoutBefore in the layout pass. The dead stripping pass is
>> still using it. Removing kindLayoutBefore entirety is the last step, after
>> modifying the dead stripping pass so that the pass works without
>> kindLayoutBefore (only with kindLayoutAfter and kindInGroup).
>>
>>
>> On Thu, Mar 27, 2014 at 12:45 PM, Shankar Easwaran <
>> shankare at codeaurora.org> wrote:
>>
>>>  On 3/27/2014 2:33 PM, Rui Ueyama wrote:
>>>
>>>  (I accidentally hit "reply" instead of "reply all", so sending it
>>> again.)
>>>
>>>  I'll add "alias" references if no objections from other reviewers.
>>> I'll probably add ELF symbol aliasing support with it, so hold on.
>>>
>>>  We cannot remove kindLayoutBefore because doing it would break dead
>>> stripping pass. We still need it for GC as GC needs backward references.
>>>
>>>  To remove kindLayoutBefore, we have to modify dead striping pass so
>>> that it creates back references internally from forward references and use
>>> it while collecting dead objects. I think I'm going to make such change,
>>> but it's going a bit large.
>>>
>>>  Submitting this change first and then doing the next step in a
>>> following patch would be better than merging the two together. Incremental
>>> change is easier to bisect in case it would breaks omething, and it's easy
>>> to understand for reviewers, too.
>>>
>>>   Do we have a flag to garbage collect atoms with lld in the current
>>> implementation ? If not removing kindLayoutBefore wouldnot affect anything
>>> right ?
>>>
>>>  Shankar Easwaran
>>>
>>> --
>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
>>>
>>>
>>
>>
>> --
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
>>
>>
>
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140327/23d8aeea/attachment.html>