[llvm-dev] Memory utilization problems in profile reader

[Xinliang David Li via llvm-dev]

Isn't that ironic as 'Dense' should mean small and compact?  Can that be
fixed?

David

On Fri, Dec 11, 2015 at 7:53 AM, Diego Novillo <dnovillo at google.com> wrote:

>
>
> On Fri, Dec 11, 2015 at 9:58 AM, Diego Novillo <dnovillo at google.com>
> wrote:
>
>> So, I traced it down to the DenseMaps in class FunctionSamples.  I've
>> replaced them with two std::vector, and the read operation causes the
>> compiler to grow from 70Mb to 280Mb.  With the DenseMaps, reading the
>> profile causes the compiler to grow from 70Mb to 3Gb.
>>
>> Somehow the DenseMaps are causing a 10x growth factor.  Those keys are
>> probably an issue.  Or perhaps we just need a different representation for
>> sample records and call sites.
>>
>
> Yes. In going through DenseMap's implementation I see that large values
> for keys will cause a lot of growth.  And the documentation confirms it
> (someday I'll learn to read documentation first).
>
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