Make ipa-ref somewhat less stupid

[Martin Liška]

On 06/16/2014 10:01 AM, Jan Hubicka wrote:
>> On 06/10/2014 08:34 AM, Jan Hubicka wrote:
>>> Hi,
>>> ipa-reference is somewhat stupid and builds its data sets for all variables including
>>> addressable and public one just to prune them out after all bitmaps are constructed.
>>> This used to make sense when the profile generation happened at compile time, but
>>> since ipa_ref datastructure was intrdocued this is a nonsense.
>>>
>>> Martin: It may be interesting to check if this solves the memory use issues with
>>> chrome.  We also may be able to re-enable ipa-ref with profile-generate as
>>> I think all the datastructures are considered to have address taken.
>> Hi,
>>     there is a link to chromium stats: https://drive.google.com/file/d/0B0pisUJ80pO1VmNHeklCRWVkOUU/edit?usp=sharing
>>
>> Both compilation were run with '-flto=6', where the upper graph adds '-fprofile-generate'. Memory footprint is IMHO acceptable, but compilation process takes twice longer with profile generation. Yeah, chromium contains a really big code base :)
> Yep, I wonder why WPA takes so much longer. Do you think you can build lto1
> with --enable-gather-detailed-mem-stats and relink with -fpre-ipa-mem-report
> -fpost-ipa-mem-report -fmem-report -Q and send me the output?  It would be nice
> to push Chromium under 4GB of WPA :)
There's report you requested: https://drive.google.com/file/d/0B0pisUJ80pO1RlRRTVBxUG5vSlE/edit?usp=sharing , produced by -fno-profile-generate. With enabled -fprofile-generate, WPA stage cannot fit to 24GB memory with enabled memory stats.

Martin

>
> Thanks a lot!
> Honza