[LLVMdev] [RFC] 3-bit Waymarking

[Gabor Greif]

On 4/22/14, Chris Lattner <clattner at apple.com> wrote:
>
> On Apr 22, 2014, at 7:28 AM, Gabor Greif <ggreif at gmail.com> wrote:
>
>> Hi devs,
>>
>> after my intentionally "playful" EuroLLVM presentation (*) I think it
>> would be time to get serious about merging to ToT. But we should
>> probably find out whether an optimized algorithm is desired at all.
>>
>> So I'd solicit comments from the code owners (Use.{h,cpp}) and anybody
>> who is interested. For closer scrutiny, the code is here:
>> <http://llvm.org/viewvc/llvm-project/llvm/branches/ggreif/waymark-64-new/>
>>
>> I do not have the equipment to perform a compile-time measurement. How
>> do folks benchmark for this nowadays? Is it a viable alternative to
>> bring the changes to ToT and compare speedups/slowdowns in the nightly
>> builds retrospectively?
>
> I saw the slides, it looks very interesting.  Have you actually measured any
> memory wins from this?

Hi Chris,

there are no memory savings, Use has still 3 pointers (the 4->3
reduction happened back in 2008). What should be faster with the new
algorithm are the "value_use_iterator::operator->" operators (i.e.
finding all Users of a Value).

Cheers,

    Gabor


>
> -Chris
>