[LLVMdev] PATCH: Use size reduction -- wave2

[Bill Wendling]

On Apr 23, 2008, at 5:07 AM, heisenbug wrote:
> On Apr 17, 4:12 am, Chris Lattner <sa... at nondot.org> wrote:
>> On Apr 16, 2008, at 11:25 AM, Dan Gohman wrote:
>>
>>>> So, my idea is that these changes are performance neutral.
>>
>> I strongly agree with Dan that we need to measure performance to
>> ensure there is no significant performance regression.
>
> Dan, Chris,
>
> finally I am in possession of hard performance data on
> a realistic testcase (kimwitu++).
>
> I have 20 measurements regading trunk LLVM and 5 with my changes
> merged in:
>
<snip>
>
> It looks like we have a degradation of 0.3%.
> The <system> and <real> times show no surprises at all.
>
> There is one important change still missing from the
> use-diet branch, viz. the capacity of the BitcodeReaderValueList
> is computed very naively with the new algorithm at each push_back.
> I left this in to see whether the algorithm scales.
> Kimwitu++ bitcode-reading puts more than 250.000 Use
> objects into a contiguous array. To get its capacity
> my algoritm has to visit more than 18 pointers each time.
>
> Tonight I will store the capacity in a member variable,
> and run comprehensive tests. I expect further speedups,
> possibly even parity.
>
> Barring any surprises I plan to merge the use-diet branch to
> trunk this weekend. Owen promised to help me doing more
> performance evaluations till then, so we get a clearer
> picture.
>
> I have also downloaded CHUD, so maybe even looking at
> (and fixing) of bottlenecks is feasible in the next days.
>
> What do you think?
>
Could you also report on memory usages?

-bw