[LLVMdev] Bitcode parsing performance

[Joey Gouly]

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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