[LLVMdev] Bitcode parsing performance

[Kevin Modzelewski]

We might have had some issues over the weekend; could you try again?  Sorry
about that.


On Fri, Jan 10, 2014 at 5:55 PM, Joey Gouly <joel.gouly at gmail.com> wrote:

> Kevin, both those files give me a 500 error, are you sure they're public?
>
>
> On 10 January 2014 22:23, Kevin Modzelewski <kmod at dropbox.com> wrote:
>
>> Ok, I updated to trunk and reran (same results); here are the original
>> and stripped bitcode files:
>> https://www.dropbox.com/s/wydh5nzt10zpcfu/stdlib.bc
>> https://www.dropbox.com/s/1oxqbatspkovmv1/stdlib.stripped.bc
>>
>> Thanks,
>> Kevin
>>
>>
>> On Fri, Jan 10, 2014 at 6:05 AM, Rafael Espíndola <
>> rafael.espindola at gmail.com> wrote:
>>
>>> On 10 January 2014 03:09, Sean Silva <chisophugis at gmail.com> wrote:
>>> > This Summer I was working on LTO and Rafael mentioned to me that debug
>>> info
>>> > is not lazy loaded, which was the cause for the insane resource usage
>>> I was
>>> > seeing when doing LTO with debug info. This is likely the reason that
>>> the
>>> > lazy loading was so ineffective for your debug build.
>>> >
>>> > Rafael, am I remembering this right/can you give more information? I
>>> expect
>>> > that this will have to get fixed before pitching LLD as a turnkey LTO
>>> > solution (not sure where in the priority list it is).
>>>
>>> In the case of LTO, there were two main issues.
>>>
>>> * Duplicate type debug information.
>>> * All metadata (including debug info) is loaded eagerly.
>>>
>>> As Eric mentioned, we can now merge type debug info from multiple
>>> translation units, which results in a smaller total size. Kevin, what
>>> llvm version are you using? Do you get a smaller combined bitcode with
>>> trunk?
>>>
>>> The issue of loading all of the debug info ahead of time is still
>>> there. We will need to fix that at some point or reduce its size
>>> further so that the impact is small enough.
>>>
>>> Cheers,
>>> Rafael
>>>
>>
>>
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>
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