[LLVMdev] [RFC] 3-bit Waymarking

[Duncan P. N. Exon Smith]

On 2014 Apr 22, at 19:46, Chris Lattner <clattner at apple.com> wrote:

> On Apr 22, 2014, at 12:26 PM, Gabor Greif <ggreif at gmail.com> wrote:
>>>> 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).
> 
> Ah, ok.  If you're looking for performance benchmarks, you could look at LTO time of something large, in that a majority of the time is spent in the mid-level optimizer.

In case you're looking for examples of "something large", clang
is a good option as long as you have enough RAM not to swap.